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The Trigeminocardiac Reflex: A Comparison with the Diving Reflex in Humans

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The trigeminocardiac reflex (TCR) has previously been described in the literature as a reflexive response of bradycardia, hypotension, and gastric hypermotility seen upon mechanical stimulation in the distribution of the trigeminal nerve. The diving reflex (DR) in humans is characterized by breath-holding, slowing of the heart rate, reduction of limb blood flow and a gradual rise in the mean arterial blood pressure. Although the two reflexes share many similarities, their relationship and especially their functional purpose in humans have yet to be fully elucidated. In the present review, we have tried to integrate and elaborate these two phenomena into a unified physiological concept. Assuming that the TCR and the DR are closely linked functionally and phylogenetically, we have also highlighted the significance of these reflexes in humans.
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Corresponding author:
Dr Tumul Chowdhury MD, DM
Department of Anesthesia
and Perioperative Medicine
2
nd
Floor, Herry Medovy House
671-William’s Ave
Health Sciences Center
University of Manitoba
Winnipeg, Canada R3E 0Z2
Phone: (204) 298 5912
Fax: (204) 787 4291
E-mail:
tumulthunder@gmail.com
1
Faculty of Sports Sciences, University of Rouen, Mont-Saint-Aignan, France
2
Department of Anesthesia and Perioperative Medicine, University of Manitoba,
Winnipeg, Canada
3
Department of Neurosurgery, University Hospital Paris, Paris, France
Submitted: 19 March 2013
Accepted: 30 June 2013
Arch Med Sci 2015; 11, 2: 419–426
DOI: 10.5114/aoms.2015.50974
Copyright © 2015 Termedia & Banach
The trigeminocardiac reflex – acomparison with
the diving reflex in humans
Frederic Lemaitre
1
, Tumul Chowdhury
2
, Bernhard Schaller
3
Abstract
The trigeminocardiac reflex (TCR) has previously been described in the
literature as a reflexive response of bradycardia, hypotension, and gas-
tric hypermotility seen upon mechanical stimulation in the distribution of
the trigeminal nerve. The diving reflex (DR) in humans is characterized by
breath-holding, slowing of the heart rate, reduction of limb blood flow and
agradual rise in the mean arterial blood pressure. Although the two reflexes
share many similarities, their relationship and especially their functional
purpose in humans have yet to be fully elucidated. In the present review, we
have tried to integrate and elaborate these two phenomena into aunified
physiological concept. Assuming that the TCR and the DR are closely linked
functionally and phylogenetically, we have also highlighted the significance
of these reflexes in humans.
Key words: reflexes, oxygen-conserving effects, breath-hold, brain,
trigeminocardiac reflex, diving reflex.
Introduction
The trigeminal cardiac reflex (TCR) and diving reflex (DR) are neuro-
genic reflexes that share many similarities in their clinical presentations
and mechanisms of action; however, their relationship and especial-
ly their functional purpose in humans have yet to be fully elucidated
[1–10]. In the present review, we have tried to integrate and elaborate
these two phenomena into aunified physiological concept. We have also
highlighted the significance and current role of these reflexes in humans.
Definitions
The trigeminocardiac reflex
The TCR is awell-established neurogenic reflex which manifests as
bradycardia, hypotension, and gastric hypermotility seen upon mechan-
ical stimulation in the distribution of the trigeminal nerve [1–3]. Initial
reports were based on animal experiments; however, TCR in neurosurgi-
cal patients was first elaborated by Schaller et al. in 1999 [3–6]. In their
key work, Schaller et al. meticulously defined TCR, and their observa-
tions are still used and commonly appreciated by researchers worldwide
Frederic Lemaitre, Tumul Chowdhury, Bernhard Schaller
420 Arch Med Sci 2, April / 2015
[1–3, 5–7]. The incidence of the TCR in neurosur-
gical procedures involving or near the trigeminal
nerve vicinity was reported to be about 10–18%
[7, 8]. These studies have usually taken a 20%
decrease in hemodynamic changes as the cut-off
limit to define TCR; therefore the true incidence
may be even higher. Moreover, the intensity of TCR
is also afactor of the intensity of stimuli like the
DR, which increases proportionally to decreasing
water temperature [1–8]. At the molecular level,
TCR is believed to be aphysiological oxygen con-
serving reflex which when incited initiates apow-
erful sympathetic system response (within afew
seconds) and thus increases the cerebral blood
flow (CBF). This regional elevation of CBF without
accompanying changes in the cerebral metabolic
rate of oxygen or glucose rapidly provides oxygen
to the brain in amore efficient manner. External
stimuli and individual factors have avariable influ-
ence on inciting the TCR in humans [8].
The diving reflex
The diving reflex in humans is characterized
by breath-holding, slowing of the heart rate, ade-
crease in cardiac output with sympathetic mediat-
ed peripheral vasoconstriction, an increase in mean
arterial blood pressure (MABP) and splenic contrac-
tion [9–16]. Blood is re-directed to more vital or-
gans (heart, brain and lung) while at the peripheral
level poor irrigation of tissues manifests as lactate
accumulation. A simultaneous splenic contraction
is also observed which indeed increases the stat-
ic apnea duration and helps in further resurgence
of red blood cells in the blood circulation [17, 18].
These phenomena also exist during repeated epi-
sodes of dynamic apnea [13]. Diving reflex is firstly
triggered by breath-holding and is augmented fur-
ther by immersion of the face into cold water [19,
20]. This response is also very prompt; therefore,
it can be considered as areflex. The inhibition of
the respiratory centers and the absence of afferent
input from pulmonary stretch receptors increase
vasomotor and cardio-inhibitory activity [21–23].
All these modifications allow economizing of the
oxygen stores for the breath-hold diver (BHD) [18,
21, 24–27]. Similar to the TCR, the DR also acts as
a protective oxygen-conserving reflex (OCR) and
aims to keep the body alive during cold water im-
mersion. Thus it protects the vital organs (the heart
and the brain) from extreme hypoxia. The DR in hu-
mans is modifiable by various factors including wa-
ter temperature, exercise, partial pressure of arte-
rial oxygen (PaO
2
), carbon dioxide tension (PaCO
2
)
and psychological factors [22].
Though the two reflexes share alot of similar-
ities, their relationship and especially their func-
tional purpose in humans have not yet been fully
elucidated. In the present article, we have tried to
elaborate the similarities as well as dissimilarities
between these two unique reflexes and therefore
possibly integrate these into one common mecha-
nism. We assume that partially, if not substantial-
ly, the TCR and the DR are closely linked function-
ally as well as phylogenetically and represent old
reflexes that are physiological in humans in the
first few months of life.
General similarities
There are obvious strong links between the
TCR and the DR that are generally accepted. Both
reflexes are based on the integrity of the trigem-
inal-brain stem reflex arc [2, 3]. In both, brady-
cardia is acommon manifestation and is induced
via reflex centers located in the medulla oblon-
gata [1, 28]. Efferent parasympathetic pathways
mediate bradycardia and similarly efferent sym-
pathetic pathways mediate peripheral vasocon-
striction.
General differences
The TCR occurs due to either peripheral or cen-
tral stimulation [3]. Stimulation of the trigeminal
nerve anywhere along the face including the nose,
orbit, eyeball and scalp (the area supplied by the
trigeminal nerve) up to the gasserian ganglion
(entry into the intracranial compartment) is con-
sidered as aperipheral TCR. The DR can be consid-
ered as aperipheral TCR. The gasserian ganglion
to the brainstem constitutes the rest of the tri-
geminal nerve course, and stimulation along this
part is considered as the central TCR. Peripheral
TCR stimulation may present with bradycardia
with or without hypotension, whereas central TCR
stimulation is usually followed by severe bradycar-
dia/asystole and hypotension [3, 8]. What differs
is that in the TCR there is asecondary decrease
in MABP, whereas in the DR the MABP gradually
increases. The difference might simply reflect the
fact that the stimulus in the DR is not ceased as
immediately as in the TCR. At present it is still not
clear whether this increase in MABP is specific for
all peripheral TCRs or only for asubgroup.
Bradycardia
It is awell-established fact that during breath-
hold diving, the heart rate (HR) becomes slower.
The reduction in HR is brought about by the in-
volvement of both central inspiratory and phasic
pulmonary afferent mechanisms [29]. Similarly,
it has been reported that tracheal intubation im-
posed during surgical procedures may give some
protection against activation of the TCR [30]. Ba-
bies under 6 months of age are excellent swim-
mers due to their DR: ababy’s air passage blocks
in contact with water, which explains the common
The trigeminocardiac reflex – acomparison with the diving reflex in humans
Arch Med Sci 2, April / 2015 421
observation of babies “swimming” under water
with open mouths.
Both reflexes, the TCR and the DR, have awell-
known reciprocal influence on cardiac vagal and
sympathetic activity in adults resulting in bra-
dycardia [31, 32]. Despite the above-mentioned
brainstem changes, the striking age-related de-
cline in occurrence of the TCR/DR in adults could
be the result of increased arterial stiffness [32].
In fact, in some instances the HR may rebound
to produce adelayed tachycardia being indicative of
atemporal difference in the activation of the auto-
nomic outflows with the increase in cardiac sympa-
thetic activity outlasting the vagal effect. Indeed, for
the DR, administration of methyl scopolamine may
unmask tachycardia that may then be abolished
by subsequent b-adrenoceptor blockade with pro-
pranolol. In addition, vagally mediated bradycardia
evoked by stimulation of nasopharyngeal receptors
was associated with simultaneous shortening of the
electrocardiogram QT interval, ameasure of ventric-
ular repolarization. Paton et al. suggested that simul-
taneous co-activation may lead to amore efficient
cardiac function, giving greater cardiac output than
activation of the sympathetic limb alone, which is
important when pumping blood into aconstricted
vascular tree as in the case of the DR and TCR [33].
Arterial blood pressure
Despite the increasing clinical reports about the
TCR, the physiological function of this brainstem
reflex is not yet fully explored [3, 33]. The one im-
portant difference is that the typical response of
the DR – or peripheral TCR – is characterized by
arterial hypertension, whereas the “classical” and
central TCR leads to arterial hypotension. Howev-
er, most of the measurements during breath-hold-
ing of blood pressure have shown no or amodest
increase in blood pressure, indicating that the DR
is less effective in humans during breath-hold div-
ing than in mammals.
Cerebral blood flow
Another physiological similarity of both reflex-
es underlines the strong link between both: The
DR results in an increase in cerebral blood flow,
although there is some constriction of the cere-
bral resistance vessels [34]. Astudy revealed that
in untrained BHDs and for apnea of 30s, the CBF
was increased by 60%; in elite BHDs and for the
same apnea time, the CBF could be increased by
200%. The increase in CBF is thus trainable [35].
Trigeminocardiac reflex, diving reflex
and the autonomous nervous system
From aphylogenetic standpoint, the autonomic
nervous system may be considered as astructure
that progressively formed in the course of evolu-
tion in order to increase cardiorespiratory survival.
This hypothesis is further underlined by the fact
that the two main divisions of the autonomic
nervous system – the sympathetic and parasym-
pathetic system – support different types of ex-
change with the external environment. The main
function of the sympathetico-adrenal system is
to organize the function of the visceral organs
for an action to be performed by the organism
in response to the (unexpected) requirements of
the environment (“fight or flight”). On the other
hand, the role of the parasympathetic system is
to prepare the visceral organs for an action to be
performed by the organism on itself: self-protec-
tion (homeostasis), regeneration and recovery and
reproduction. This system strongly underlies phy-
lo- and ontogenetically determined patterns.
The fact that cardiac vagal activity is similar
after stimulation of the TCR and DR supports the
hypothesis that the DR and TCR are closely linked.
Whereas the goal of the DR may be clear (saving
the organism from drowning with an oxygen-con-
serving effect), the purpose of the TCR remains
less obvious.
Trigeminocardiac reflex and diving reflex as
the basis of other pathologies?
The DR is the reflex mechanism most frequent-
ly considered in the etiopathogenesis of sudden
infant death syndrome (SIDS) or crib death [14,
36–38]. This is defined as the sudden, unexpect-
ed death of an infant younger than 1 year of age
which remains unexplained after a thorough in-
vestigation, including acomplete autopsy, exam-
ination of the death scene, and a review of the
clinical history [39].
Recent studies on the pathophysiology of SIDS
have focused on the autonomic nervous system
and have disclosed anomalies – mostly congenital
– located in the brainstem [40–46]. In over 50% of
SIDS cases, histological examination of the brain-
stem on serial sections showed underdevelopment
of the brainstem, e.g. mono-, bilateral or partial hy-
poplasia, delayed neuronal maturation or decreased
neuronal density of the arcuate nucleus, which is an
important center controlling breathing activity. Un-
derdevelopment of the pre-Bötzinger, of the parab-
rachial Kölliker-Fuse complex and of the hypoglossal
nucleus was also detected [38, 41, 42, 44, 46]. Over-
all, the abnormalities of the autonomic nervous sys-
tem described in SIDS may explain the occurrence
of SIDS by vagal inhibition elicited by the DR [40,
43]. In the case of SIDS, apossible role of parenteral
cigarette smoking in the pathogenesis of arcuate
nucleus hypoplasia is discussed, suggesting asimi-
lar defect in patients who are susceptible to the TCR
during neurosurgical operations [43].
Frederic Lemaitre, Tumul Chowdhury, Bernhard Schaller
422 Arch Med Sci 2, April / 2015
Trigeminocardiac reflex, diving reflex
and phylogenesis
As amatter of fact, the oxygen-conserving DR
and its subsets seem to persist in humans [7, 8,
31]. In man, DR may be considered as an archaic
relict which has functional importance in phylo-
genetically lower-ranked animals such as diver
birds or amphibians. The DR is indeed particularly
developed in birds to provide inhibition of cardiac
and breathing activity during underwater feeding,
necessary for individual and species survival [38].
In mammals, the DR is elicited by contact of the
face with cold water and involves breath-holding,
decreased ventilation, bradycardia, intense pe-
ripheral vasoconstriction, and increased MABP,
with the purpose of preventing drowning and
providing an oxygen reservoir in the lungs, main-
taining the heart and the brain adequately oxy-
genated at the expense of less hypoxia-sensitive
organs [47].
In humans, washing the face or plunging into
cold water results in profound bradycardia and re-
distribution of the blood flow to the lungs, brain
and heart [36]. Though considered to be the most
powerful autonomic reflex, the purpose of this re-
flex, especially the breath-hold (BH) response in
humans, is equivocal [47]. In newborns and infants
with adevelopmental defect of the brainstem and
its reflexogenic centers, there were found more
deaths due to apnea or cessation of breathing [14,
36, 38]. Thus the role of the brainstem as part of
the reflex cannot be ignored.
There is fine tuning between the reflex and the
bodily response; however, exaggeration of this
protective response could be detrimental and has
been implicated in causing SIDS. This reflex can
also become manifest in adult with acquired bul-
bospinal disease [38]. In elite BHDs, such problems
after along period of BH training are unknown.
In humans, the DR may be psychologically me-
diated and paradoxically may be lethal. Wolf in
1978 described sudden cardiac death from the
DR in subjects who developed sinus arrest while
thinking of and/or preparing to dive [38, 48].
Thereafter, no similar case has been reported, so
this is arare occurrence. But the DR may be train-
able. It was found that BHDs presented biphasic
HR kinetics and two heart rate decreases [49]. The
second HR decrease, which was concomitant to
the pronounced arterial oxygen saturation (SaO
2
)
decrease, was also simultaneous with amarked
increase in the root mean square successive dif-
ference of the R-R intervals (RMSSD), avagal in-
dex. On the other hand, untrained BHDs showed
only one HR decrease, which appeared before
the concomitant SaO
2
and RMSSD changes. This
study indicates that baroreceptor reflex stimula-
tion and hypoxia may be the key mechanisms in-
volved in producing such abiphasic HR response
of BHDs and thus help in prolongation of BH du-
ration [49].
In fact, the DR had been shown to be effective
in conserving oxygen in humans during BH at
rest [21, 50]. Trained BHDs with severe bradycar-
dia were able to slow the arterial desaturation by
afactor of two or three [50]. This bradycardia is
also accentuated with larger BHD pulmonary vol-
umes before apnea, stimulating the activity in the
slowly adapting pulmonary stretch receptors more
powerfully and resulting in alower HR decrease in
the first phase. The decreasing HR in phase one
also probably accounted for the slight diminution
in cardiac output and, consequently, a slight in-
crease in total peripheral resistance at the end of
this first phase [51]. It would also account for an
increase in stroke volume, which in turn would be
astimulus for the high-pressure aortic and carot-
id baroreceptor [52]. During the second phase, as
BH duration increased and the alveolar volume
decreased, the likely pulmonary volume decreas-
es may have further reduced the activity in the
pulmonary stretch receptors and, consequently,
further reduced the HR [53]. It can be speculated
that hypoxia would result in greater arterial che-
moreceptor stimulation and thus would further
accentuate bradycardia (Figure 1) [15].
Rossi described acase of lethal cardiac arrest
in a young army recruit who succumbed to the
common barracks prank of pouring amesstin of
cold water on the face of asleeping comrade [38].
Abrupt vagal hyperexcitation from an aberrant DR
due to trigeminal-ophthalmic triggering was the
most plausible explanation, but no aimed control
Figure 1. Static apnea of an elite breath-hold diver.
The position is not conventional because usually
they are lying at the surface
The trigeminocardiac reflex – acomparison with the diving reflex in humans
Arch Med Sci 2, April / 2015 423
of the central nervous system was carried out,
suggesting that there may be another reflexogen-
ic arc than in the TCR.
The higher purpose of the TCR in mammals –
especially humans – is at present not fully under-
stood. We think that avery plausible explanation
may be the following: The TCR may be important
for breast-feeding during the first months of life.
At that time the newborn drinks for a relatively
long period of time with its face literally against
the mother. Consequently, the upper airways are
partially obstructed by the mother’s body, result-
ing in hypoventilation. The TCR which is elicited by
mechanical stimulation results in bradycardia, hy-
potension and increase in the cerebral blood flow
in order to avoid damage to the developing brain.
The role of the gastric hypermobility, another typi-
cal reaction elicited by stimulation of the TCR, also
becomes evident from this view. This also may ex-
plain the psychological or emotional dimension of
these reflexes.
Schaller et al. in their studies have also hypoth-
esized on grounds of precise clinical and physio-
logical observations that the term TCR subsumes
the “classical” central TCR and the peripheral DR
or oculocardiac reflex [54]. Grogaard and Sundell
studied the “trigeminal diving reflex” in newborn
lambs, reporting that this reflex is significantly
reduced after treatment with b-adrenergic ago-
nists [55]. As discussed above, we think that even
from aphylogenetic standpoint there is a lot of
evidence that both reflexes are closely linked and
may interact with each other. They are phyloge-
netically old reflexes especially useful for the un-
derwater feeding of diver-birds and amphibians. In
humans they may be important during the breast
feeding period where the babies’ upper airways
are partially obstructed by the close body contact
with the mother. Their role in the pathogenesis of
SIDS and for potential complications during neu-
rosurgical procedures is also highly important. In
fact, abetter understanding of these reflexes will
result in better patient care.
Trigeminocardiac reflex and diving reflex
clinical cases
Trigeminocardiac reflex case
A60-year-old male patient with adiagnosis of
right-sided vestibular schwannoma underwent
tumor resection via a retrosigmoid (suboccipi-
tal approach) approach. His medical history was
significant for long standing hypertension (on
irbesartan – an angiotensin receptor blocker) and
ahistory of smoking (14 PPD). His baseline MABP
was 73 mm Hg and heart rate was 65 beats per
minute. Two hours after skin incision, his MABP
dropped to 43 mm Hg (40.8% drop from base-
line) and concomitantly, his heart rate dropped to
40 beats per minute (38% drop from baseline).
Then, the surgical procedure was discontinued;
he was given atropine 0.6 mg intravenously. Af-
ter 5 min, his MABP and heart rate stabilized to
physiological values and the surgical procedure
was carried out successfully to the end without
any further episodes of TCR. His oxygen saturation
was 100% and no hypercarbia occurred. The post-
operative course was uneventful.
Diving reflex case
An expert BHD (man), 33 years old, with 11
years of BH practice and a forced vital capacity
(FVC) of 6.7 l (124% of predicted values), per-
formed a static BH of 7 min 12 s lying on the
surface in aswimming pool. Heart rate behavior
and SaO
2
were continuously recorded during one
maximal BH. Short-term changes in SaO
2
, HR, the
root mean square successive difference of the R-R
intervals (RMSSD), and the time-domain heart
rate variability (HRV) index were calculated over
the complete BH duration. This BHD presented
biphasic HR kinetics (Figure 2), with two HR de-
creases (32% and 64% of initial HR). The second
HR decrease, which was concomitant to the pro-
nounced SaO
2
decrease, was also simultaneous
with amarked increase in RMSSD. Aclassically un-
trained BHD showed only one HR decrease (about
20–30% of initial HR), which appeared before the
concomitant SaO
2
and RMSSD changes [49].
In fact, for this BHD the cardiovascular diving re-
sponse was effective in conserving oxygen during
BH at rest. This elite BHD with astrong bradycardia
was able to slow the arterial desaturation accord-
ing to previous studies [50]. The BHD also had high-
er FVC than predicted values, which can at the be-
ginning of the BH powerfully stimulate the activity
in the slowly adapting pulmonary stretch receptors
110
100
90
80
70
60
50
40
30
Figure 2. Static BH of 7min and 12s in one expert
BHD. Heart rate [2] and SaO
2
were recorded con-
tinuously before, during and after the BH duration
(presented between the two vertical lines)
0 20 40 60 80 100 120
Time (%)
SaO
2
(%) HR [bpm]
Static BH (7 min 12 s)
Frederic Lemaitre, Tumul Chowdhury, Bernhard Schaller
424 Arch Med Sci 2, April / 2015
and result in astrong HR decrease in the first phase.
The decreasing HR in phase one also probably ac-
counted for the slight diminution in cardiac output
with an increase in stroke volume, which in turn
would be a stimulus for the high-pressure aortic
and carotid baroreceptors [52]. During the second
phase, as BH duration increased, the activity in the
pulmonary stretch receptors would decrease and,
consequently, reduce HR even more [53]. Hypoxia
would also result in greater arterial chemoreceptor
stimulation and would accentuate bradycardia [15].
Thus hypoxia could enhance vasoconstriction and
thus the venous return, stimulating baroreceptors
and again reducing HR [15]. This case indicates that
baroreflex stimulation and hypoxia may be involved
in the biphasic HR response and thus in the long
BH duration and that the DR may be trained.
Current role of trigeminocardiac reflex
vs. diving reflex
Arecent review highlighted the clinical implica-
tions of these reflexes. The DR has been used to
treat supraventricular tachycardia (SVT) [56]. This
reflex is incited by various maneuvers including im-
mersion of the face in preset cold water and breath
holding exercises. Even nasopharyngeal suction
aborted the episodes of SVT in pediatric patients
too [57]. However, arecent animal (pontomedullary
transaction) experiment suggested that the medul-
la and spinal cord may be the primary target site
to complete the reflex arc [58]. On the other hand,
the TCR has been investigated as a protective re-
flex during sleep bruxism [59]. Due to periods of
micro-arousals, tachycardia starts; however, masti-
catory movements rapidly incite the TCR and slow
down the heart rate. Although it was previously
thought that local anesthetic could block incitation
of the TCR, many studies have shown that local an-
esthetic is not effective to blunt the TCR [60, 61].
Similarly, local anesthetic could not blunt the DR ei-
ther. These features indeed highlight the possibility
of differential sensitivity of nerve fibers for inciting
these reflexes, and the stretch could still be reflex-
ogenic even with the blocked nerve. The reflexog-
enic mechanisms of both the reflexes, if not sub-
stantially, may partially share the pathways. The
different receptors and related stimuli may possibly
play acomplex role to elucidate the two different
mechanisms; however, these are still not fully eluci-
dated and warrant further research [62].
Conclusions
There exists aclose association between these
two unique neurogenic reflexes. Both are physio-
logical, protective reflexes and pose some clinical
significance; however, both can be detrimental if
not properly regulated either due to absence of
physiological control or anatomical defect. The DR
can be considered as peripheral asub-form of the
TCR. However, so far, there are no convincing ex-
perimental or histopathological data to prove these
connections, and thus further studies are warrant-
ed. In cases of sudden death attributed to diving or
trigeminal stimulation, meticulous examination of
the brainstem on serial sections may have a cru-
cial role in indentifying morphological substrates
responsible for these reflexes [38, 43, 44, 63–68].
In the future, it will be very interesting to exam-
ine the TCR in elite breath-hold divers who develop
astrong DR.
Conflict of interest
Dr Bernhard Schaller, one of the co-authors of
this review, is the co-editor of the journal (“Ar-
chives of Medical Science”).
The authors declare no conflict of interest.
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... This can be explained by the fact that using the handheld fan on the face reduces heart rate and causes changes in dyspnea perception through the stimulation of the trigeminal nerve, as well as through the diving reflex. The diving reflex is an adaptation that involves reducing heart rate to reduce the body's need for oxygen when the face comes into contact with cold (Lemaitre et al., 2015). ...
Article
Background: The application of a handheld fan may reduce patients' shortness of breath and increase their activity tolerance by enabling cooling and air flow into the second and third branches of the trigeminal nerve. Objectives: The aim of the study was to assess the effects of directing a handheld fan toward the face in the management of lung cancer-related dyspnea. Methods: Using a randomized controlled experimental design, 96 inpatients with lung cancer were evaluated, with the experimental group (n = 49) using a handheld fan to manage dyspnea for 14 days. Dyspnea, respiration rate, oxygen saturation, heart rate, and quality of life were assessed for both groups. Findings: A statistically significant difference was found in dyspnea scores between groups on the first, seventh, and fourteenth days of fan application, and statistically significant differences were found between groups in dyspnea scores, respiration rates, oxygen saturation, heart rate, and quality of life on the fourteenth day of application.
... 1 To date, a breadth of research exists that has delineated the physiological characteristics of breath-hold divers, as well as the responses that occur during and/or following prolonged apnoeic bouts (e.g, the diving response, trigeminocardiac reflex, splenic contractions, erythropoietic responses, etc.). [1][2][3][4][5][6][7][8] In contrast, there is a paucity of literature concerning the possible health implications associated with exposure to such activities. [9][10][11][12][13][14] Emerging evidence indicates that a single, maximal static apnoeic attempt is capable of transiently disrupting the blood-brain barrier 9,13 and instigates neuronal-parenchymal damage 11 but is not associated with cardiac injury. ...
Article
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Purpose-This study sought to explore, for the first time, the effects of repeated maximal static and dynamic apnoeic attempts on the physiological milieu by assessing cerebral, cardiac and striatal muscle stress-related biomarkers in a group of elite breath-hold divers (EBHD). Methods-Sixteen healthy males were recruited (EBHD=8; controls=8). On two separate occasions EBHD performed two sets of five repeated maximal static apnoeas (STA) or five repeated maximal dynamic apnoeas (DYN). Controls performed a static eupnoeic protocol to negate any effects of water immersion and diurnal variation on haematology (CTL). Venous blood samples were drawn at 30, 90, and 180-mins after each protocol to determine S100β, neuron-specific enolase (NSE), myoglobin and high sensitivity cardiac troponin T (hscTNT) concentrations. Results-S100β and myoglobin concentrations were elevated following both apnoeic interventions (p<0.001; p≤0.028, respectively) but not after CTL (p≥0.348). S100β increased from baseline (0.024±0.005µg/L) at 30 (STA, +149%, p<0.001; DYN, +166%, p<0.001) and 90 mins (STA, +129%, p<0.001; DYN, +132%, p=0.008) following the last apnoeic repetition. Myoglobin was higher than baseline (22.3±2.7ng/mL) at 30 (+42%, p=0.04), 90 (+64%, p<0.001) and 180 mins (+49%, p=0.013) post-STA and at 90 mins (+63%, p=0.016) post-DYN. Post-apnoeic S100β and myoglobin concentrations were higher than CTL (STA, p<0.001; DYN, p≤0.004). NSE and hscTNT did not change from basal concentrations after the apnoeic (p≥0.146) nor following the eupnoeic (p≥0.553) intervention. Conclusions-This study suggests that a series of repeated maximal static and dynamic apnoeas transiently disrupt the blood-brain barrier and instigate muscle injury but do not induce neuronal-parenchymal damage or myocardial damage.
... From the literature data, it may be suggested that the slowing of the HR was the result of the activation of cardiac vagal fibers following the stimulation of peripheral chemoreceptors by hypoxemia (Lemaitre et al., 2005(Lemaitre et al., , 2008Wierzba and Ropiak, 2011;Willie et al., 2015). Moreover, stimulation of parasympathetic fibers leads to increased bradycardia resulting from immersing the face in the water (Lemaitre et al., 2015). The phasic HR responses throughout a dry, static breath-holding in elite divers (Perini et al., 2008) and three distinct phases (i.e., an initial reduction-phase I, plateau-phase II, and further reductionphase III) have been observed. ...
Article
Full-text available
Given the previous evidence that breath-hold diving is a cause of physiological stress, this study aimed to determine whether a combination static and dynamic apnea would affect total oxidant status, nitric oxide, heat shock proteins and cardiovascular parameters in elite freedivers. Thirteen finalists of the World and European championships in swimming pool breath-hold diving participated in the study. Whole-body plethysmography and electrocardiography was performed to determine the cardiorespiratory variables at baseline and during the simulation static apnea. An assessment of the heart rate, blood oxygen saturation and biochemical variables was performed before and in response to a combination of a static followed by a dynamic apnea. Static and dynamic breath-holding had a significant effect on oxidative stress, as evidenced by an increase in the total oxidant status/capacity ( p < 0.001). The post apnea concentrations of heat shock proteins 27 (HSP27) were significantly elevated ( p < 0.03, but total antioxidant status (TAS), HSP90, HSP70, and nitric oxide (NO) changes were not significant. levels under the influence of the static and dynamic breath-hold protocol. A significant positive correlation between HSPs and TAS ( r = 0.63; p < 0.05) as well as NO levels was associated with beneficial cardiovascular adaptation. An increase in serum HSP27 levels mediated in nitric oxide levels could explain its important role in improving cardiovascular functions in elite freedivers. Further studies are necessary to explain the exact mechanisms of breath holds training of cardiovascular adaptation responsible for maintaining adequate oxygen supply in elite divers.
... This suggests that face immersion did not impact peripheral vasoconstriction in our study. A likely explanation would be that, while face immersion triggers the trigeminal nerve which regulates vagal activity and thus improves bradycardia (Lemaitre and Schaller, 2015), peripheral vasoconstriction results from sympathetic activation (Leuenberger et al., 2001) and would therefore be independent from face immersion. This is however in contrast with the observations of stronger increases in MSNA in short FIA compared to DRA (Fagius and Sundlöf, 1986) and greater increases in MAP during short dynamic FIA compared to DRA (Andersson et al., 2002), both supporting an enhanced sympathetic activation in response to face immersion (Heindl et al., 2004). ...
Article
Full-text available
Introduction: Acute apnea evokes bradycardia and peripheral vasoconstriction in order to conserve oxygen, which is more pronounced with face immersion. This response is contrary to the tachycardia and increased blood flow to muscle tissue related to the higher oxygen consumption during exercise. The aim of this study was to investigate cardiovascular and metabolic responses of dynamic dry apnea (DRA) and face immersed apnea (FIA). Methods: Ten female volunteers (17.1 ± 0.6 years old) naive to breath-hold-related sports, performed a series of seven dynamic 30 s breath-holds while cycling at 25% of their peak power output. This was performed in two separate conditions in a randomized order: FIA (15°C) and DRA. Heart rate and muscle tissue oxygenation through near-infrared spectroscopy were continuously measured to determine oxygenated (m[O 2 Hb]) and deoxygenated hemoglobin concentration (m[HHb]) and tissue oxygenation index (mTOI). Capillary blood lactate was measured 1 min after the first, third, fifth, and seventh breath-hold. Results: Average duration of the seven breath-holds did not differ between conditions (25.3 s ± 1.4 s, p = 0.231). The apnea-induced bradycardia was stronger with FIA (from 134 ± 4 to 85 ± 3 bpm) than DRA (from 134 ± 4 to 100 ± 5 bpm, p < 0.001). mTOI decreased significantly from 69.9 ± 0.9% to 63.0 ± 1.3% (p < 0.001) which is reflected in a steady decrease in m[O 2 Hb] (p < 0.001) and concomitant increase in m[HHb] (p = 0.001). However, this was similar in both conditions (0.121 < p < 0.542). Lactate was lower after the first apnea with FIA compared to DRA (p = 0.038), while no differences were observed in the other breath-holds. Conclusion: Our data show strong decreases in heart rate and muscle tissue oxygenation during dynamic apneas. A stronger bradycardia was observed in FIA, while muscle oxygenation was not different, suggesting that FIA did not influence muscle oxygenation. An order of mechanisms was observed in which, after an initial tachycardia, heart rate starts to decrease after muscle tissue deoxygenation occurs, suggesting a role of peripheral vasoconstriction in the apnea-induced bradycardia. The apnea-induced increase in lactate was lower in FIA during the first apnea, probably caused by the stronger bradycardia.
... Firstly, pressure induces centralization of peripheral blood volume due to hydrostatic pressure, causing activation of cardiac stretch receptors and baroreceptors (Chouchou et al., 2020). Secondly, the role of the trigeminocardiac reflex (Lemaitre et al., 2015) and thirdly, the role of cold induces PNS activation [mainly the same mechanism as in pressure (Ihsan et al., 2016)]. Due to the study setting in this research, we could view the aforementioned parameters separately. ...
Article
Full-text available
Introduction Technical diving is very popular in Finland throughout the year despite diving conditions being challenging, especially due to arctic water and poor visibility. Cold water, immersion, submersion, hyperoxia, as well as psychological and physiological stress, all have an effect on the autonomic nervous system (ANS). Materials and methods To evaluate divers’ ANS responses, short-term (5 min) heart rate variability (HRV) during dives in 2–4°C water was measured. HRV resting values were evaluated from separate measurements before and after the dives. Twenty-six experienced closed circuit rebreather (CCR) divers performed an identical 45-meter decompression dive with a non-physical task requiring concentration at the bottom depth. Results Activity of the ANS branches was evaluated with the parasympathetic (PNS) and sympathetic (SNS) indexes of the Kubios HRV Standard program. Compared to resting values, PNS activity decreased significantly on immersion with face out of water. From immersion, it increased significantly with facial immersion, just before decompression and just before surfacing. Compared to resting values, SNS activity increased significantly on immersion with face out of water. Face in water and submersion measures did not differ from the immersion measure. After these measurements, SNS activity decreased significantly over time. Conclusion Our study indicates that the trigeminocardiac part of the diving reflex causes the strong initial PNS activation at the beginning of the dive but the reaction seems to decrease quickly. After this initial activation, cold seemed to be the most prominent promoter of PNS activity – not pressure. Also, our study showed a concurrent increase in both SNS and PNS branches, which has been associated with an elevated risk for arrhythmia. Therefore, we recommend a short adaptation phase at the beginning of cold-water diving before physical activity.
... Apnoea, as the lone stimuli, is sufficient to elicit bradycardia, however, when apnoea is coupled with face immersion, a stronger bradycardial response is noticeable (Andersson et al. 2000;Ferrigno et al. 1997;Hayashi et al. 1997;Shamsuzzaman et al. 2014). The profound influences of facial cooling largely stem from stimulation of the trigeminal nerve activity (i.e., facial cold receptors innervated by the ophthalmic nerve), which evidently evoke a 'trigeminocardiac reflex', also referred to as the diving-reflex (Lemaitre et al. 2015). The magnitude of this reflex is highly variable and primarily depends on the water temperature the facial cold receptors are exposed to (Ferrigno et al. 1997;Schagatay and Holm 1996). ...
Article
Full-text available
Breath-hold diving is an activity that humans have engaged in since antiquity to forage for resources, provide sustenance and to support military campaigns. In modern times, breath-hold diving continues to gain popularity and recognition as both a competitive and recreational sport. The continued progression of world records is somewhat remarkable, particularly given the extreme hypoxaemic and hypercapnic conditions, and hydrostatic pressures these athletes endure. However, there is abundant literature to suggest a large inter-individual variation in the apnoeic capabilities that is thus far not fully understood. In this review, we explore developments in apnoea physiology and delineate the traits and mechanisms that potentially underpin this variation. In addition, we sought to highlight the physiological (mal)adaptations associated with consistent breath-hold training. Breath-hold divers (BHDs) are evidenced to exhibit a more pronounced diving-response than non-divers, while elite BHDs (EBHDs) also display beneficial adaptations in both blood and skeletal muscle. Importantly, these physiological characteristics are documented to be primarily influenced by training-induced stimuli. BHDs are exposed to unique physiological and environmental stressors, and as such possess an ability to withstand acute cerebrovascular and neuronal strains. Whether these characteristics are also a result of training-induced adaptations or genetic predisposition is less certain. Although the long-term effects of regular breath-hold diving activity are yet to be holistically established, preliminary evidence has posed considerations for cognitive, neurological, renal and bone health in BHDs. These areas should be explored further in longitudinal studies to more confidently ascertain the long-term health implications of extreme breath-holding activity.
... Nasal reflexes can emerge Fig. 2 The mean systolic and diastolic blood pressure changes of the outfracture and bipolar cauterization mechanically (e.g., with a probe) through various stimuli, such as hypertonic saline, cold and hot air, histamine, allergens, nicotine, bradykinin and capsaicin [8], as well as by the trigeminocardiac reflex (TCR) during maxillofacial surgery. Various subtypes of TCR have been reported, some of which include peripheric (oculocardiac reflex, nasocardiac reflex, maxillomandibular reflex), gasserian ganglion-type and central TCR [23]. To date, the TCR subtypes have been reported in studies on maxillofacial operations [24][25][26]. ...
Article
Full-text available
Purpose To compare the autonomic reflexes caused by inferior turbinate outfracture or bipolar cauterization for inferior turbinate reduction surgery. Methods The investigators designed and implemented a prospective study composed of 80 patients who underwent a septoplasty with inferior turbinate reduction. The predictor variable was the type of bilateral reduction operation and included inferior turbinate outfracture with a freer elevator and 20 watts bipolar cauterization for 15 s per side after septoplasty. The primary outcome variable was the intraoperative changes of the heart rate monitored preoperatively and 20 s, 1 min, and 4 min after the turbinate reduction procedure. Other variables were systolic and diastolic blood pressure alterations after the inferior turbinate outfracture or bipolar cauterization procedure. Descriptive and bivariate statistics were computed and the P-value was set at .05. Results The sample was composed of 160 procedures in 80 patients grouped as follows: Outfracture (n = 100) and Cauterization (n = 60). There were no significant differences between the ages; grades of the turbinate hypertrophy; preoperative heart rates; and intraoperative 4th-minute heart rates, systolic and diastolic blood pressures. However, baseline systolic (p < 0.001) and diastolic (p < 0.001) blood pressures of the bipolar cauterization group were higher than outfracture group. Bipolar cauterization did not cause any significant changes in the heart rate, systolic and diastolic blood pressures. Inferior turbinate outfracture procedure caused a significant increase in heart rate (65.4 ± 9.82, p < 0.001), systolic (103 ± 8.62, p < 0.001) and diastolic (63.5 ± 7.37, p < 0.001) blood pressures. Conclusion The results of this study suggest that during the inferior turbinate outfracture procedure, it is important to closely monitor sympathetic and parasympathetic reflexes. The surgeon, and anesthesiologist, must be aware of the early stages of the autonomic reflexes during turbinate reduction.
... This diving reflex involves vagally mediated bradycardia, sympathetically mediated peripheral vasoconstriction with an increase in blood pressure, changes in cardiac output and spleen contraction (Dujic & Breskovic, 2012;Ferretti, 2001). The integration of both sympathetic and parasympathetic pathways underlies the ontogenetic origin of the dive responses (Lemaitre et al., 2015). In trained BHDs, dynamic cerebral autoregulation is acutely impaired during maximal BH (Cross et al., 2014), cerebral oxidative metabolism is decreased and a disruption of the blood-brain barrier has also been suggested (Bain et al., 2016(Bain et al., , 2018. ...
Article
The aim of this study was to investigate the impact of breath-hold diving strategies regarding loss of consciousness (LOC). Three international competitions were examined through video in constant weight diving with (CWT) or without (CNF) fins. We analysed three breath-hold parameters (time, speed, and movements count) for the following phases: active descent, passive descent, turning, and ascent. Divers who had LOC during CNF were slower in the active descent phase, faster in the passive descent phase with a longer turn, and slower in the ascent phase than divers who did not have LOC. They also had lower amplitude and higher frequency. Men were deeper (72.9 m vs. 56.3 m) for a longer dive time (181.1 s vs. 154.6 s), faster, with a greater amplitude than women. In CWT, divers with an LOC had longer dive times (197 s vs. 167 s) with a faster active descent phase. Men had lower amplitude and greater frequency than women. This is the first study showing that breath-hold divers undergoing an LOC event shown differences in efficiency during CWT and CNF regarding velocities, amplitudes, and frequencies. In conclusion, our results suggest that the speed parameter during active descent phase influence the LOC.
... The early onset of bradycardia, part of the diving response, is thought to result from the removal of pulmonary stretch afferents, being strengthened by the cold pressor response (i.e. cold face immersion) through the trigeminus pathway (Lemaitre, Chowdhury, & Schaller, 2015). In the present study, we have shown that the NX phase of BH, whether experienced by BHDs or NDs, did not parallel with any changes in fractal-like behaviour of cardiac cycles, nor in the occurrence of cardiac arrhythmias. ...
Article
Breath-hold divers are known to develop cardiac autonomic changes and brady-arrthymias during prolonged breath-holding (BH). The effects of BH-induced hypoxemia were investigated upon both cardiac autonomic status and arrhythmogenesis by comparing breath-hold divers (BHDs) to non-divers (NDs). Eighteen participants (9 BHDs, 9 NDs) performed a maximal voluntary BH with face immersion. BHDs were asked to perform an additional BH at water surface to increase the degree of hypoxemia. Beat-to-beat changes in heart rate (HR), short-term fractal scaling exponent (DFAα1), the number of arrhythmic events [premature ventricular contractions (PVCs), premature atrial contractions (PACs)] and peripheral oxygen saturation (SpO2) were recorded during and immediately following BH. The corrected QT-intervals (QTc) were analyzed pre- and post-acute BH. A regression-based model was used to split BH into a normoxic (NX) and a hypoxemic phase (HX). During the HX phase of BH, BHDs showed a progressive decrease in DFAα1 during BH with face immersion (p<0.01) and BH with whole-body immersion (p<0.01) whereas NDs did not (p>0.05). In addition, BHDs had more arrhythmic events during the HX of BH with whole-body immersion when compared to the corresponding NX phase (5.9 ± 6.7 vs 0.4 ± 1.3; p<0.05; respectively). The number of PVCs was negatively correlated with SpO2 during BH with whole-body immersion (r=-0.72; p<0.05). The hypoxemic stage of voluntary BH is concomitant with significant cardiac autonomic changes toward a synergistic sympathetic and parasympathetic stimulation. Co-activation led ultimately to increased bradycardic response and cardiac electrophysiological disturbances.
Article
The study aimed to correlate between the stimulated nerve, intensity of trigeminovagal reflex (TVR), and neuropathophysiological pathway by which the efferent arc is activated. Material and methods: A retrospective study included patients who developed TVR during the surgical management of mandibular, midface, and orbital fractures. The reflex was divided into type I, II, III, and IV-TVR according to the following nerves: ophthalmic, maxillary, mandibular, and non-trigeminal nerves, respectively. The magnitude of hemodynamic drops was identified at the intraoperative baseline, during reflex, and postoperatively. The needed time to elicit the reflex, frequency and duration, need for medical intervention, and sequence of the drop were also recorded. P - values < 0.05 was considered significant. Out of 260 patients’ files were reviewed, the TVR was observed in only 30 (11.55 %) patients. The ophthalmic nerve activation significantly caused the greatest intensity and magnitude of hemodynamic drop, followed by maxillary nerve, then mandibular division, and the lowest one was non-trigeminal nerves. The highest mean of drops in the mean arterial blood pressure (MABP) was 62.92 ± 2.39 with the type ITVR, whereas those of the type II, III, and IV were 75.5 ±3.98, 81.02±1.31, and 82.22±1.85, respectively. Also, the type I-TVR led to the greatest decrease in the heart rate (HR) with the mean equaled to 52.31± 3.91. The drop percentage in the MABP was -30.5, -17.5, -12, -10.08 for type I, II, III, and IV, whereas those of the HR were - 33.9, -27.13, -26.6, and -25 with type I, II, III, and IV, respectively. All results showed highly significant differences with p-values less than 0.001 when comparing between the baseline and intraoperative values of each TVR type. There is a positive correlation between the activated pathway of the TVR and the intensity of its efferent arc response due to the neural pathway of each division in the brainstem circuitry. Understanding of the pathophysiology and mechanism of the TVR, together with the rapid recognition and treatment could prevent serious negative outcomes, especially when the ophthalmic nerve is stimulated. 1Introduction
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Trigeminocardiac reflex (TCR) is a brainstem reflex that manifests as sudden onset of hemodynamic perturbation in blood pressure (MABP) and heart rate (HR), as apnea and as gastric hypermotility during stimulation of any branches of the trigeminal nerve. The molecular and clinical knowledge about theTCRis in a constant growth since 1999,what implies a current need of a review about its definition in this changing context. Relevant literature was identified through searching in PubMed (MEDLINE) and Google scholar database for the terms TCR, oculocardiac reflex, diving reflex, vasovagale response. The definition of the TCR varies in clinical as well as in research studies. The main difference applies the required change of MABP and sometimes also HR, which most varies between 10% and 20%. Due to this definition problem, we defined, related to actual literature, 2 major (plausibility, reversibility) and 2 minor criteria (repetition, prevention) for a more proper identification of the TCR in a clinical or research setting. Latest research implies that there is a need for a more extended classification with 2 additional subgroups, considering also the diving reflex and the brainstem reflex. In this review, we highlighted criteria for proper definition and classification of the TCR in the light of increased knowledge and present a thinking model to overcome this complexity. Further we separately discussed the role of HR andMABP and their variation in this context.As another subtopic we gave attention to is the chronic TCR; a variant that is rarely seen in clinical medicine.
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The trigeminocardiac reflex (TCR) is defined as the sudden onset of parasympathetic dysrhythmia, sympathetic hypotension, apnea, or gastric hypermotility during stimulation of any of the sensory branches of the trigeminal nerve. Clinically, the TCR has been reported in all the surgical procedures in which a structure innervated by the trigeminal nerve is involved. Although, there is an abundant literature with reports of incidences and risk factors of the TCR; the physiological significance and function of this brainstem reflex has not yet been fully elucidated. In addition, there are complexities within the TCR that requires examination and clarification. There is also a growing need to discuss its cellular mechanism and functional consequences. Therefore, the current review provides an updated examination of the TCR with a particular focus on the mechanisms and diverse nature of the TCR.
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Introduction: Our aim was to evaluate the differences in the early hemodynamic response to the tilt test (HUTT) in patients with and without syncope using impedance cardiography (ICG). Material and methods: One hundred twenty-six patients (72 female/48 male; 37 ±17 years) were divided into a group with syncope (HUTT(+), n = 45 patients) and a group without syncope (HUTT(–), n = 81 patients). ECG and ICG signals were continuously recorded during the whole examination, allowing the calculation of heart rate (HR), stroke volume (SV), and cardiac output (CO) for every beat. The hemodynamic parameters (averaged over 1 min) were analyzed at the following points of the HUTT: the last minute of resting, the period immediately after the tilt (0 min), 1 min and 5 min after the maneuver. The absolute changes of HR, SV and CO were calculated for 0, 1, and 5 min after the maneuver in relation to the values at rest (ΔHR, ΔSV, ΔCO). Also, the percentage changes were calculated (HRi, SVi, COi). Results: There were no differences between the groups in absolute and percentage changes of hemodynamic parameters immediately after and 1 min after tilting. Significant differences between the HUTT(+) and HUTT(–) groups were observed in the 5th min of tilting: for ΔSV (–27.2 21.2 ml vs. –9.7 ±27.2 ml; p = 0.03), ΔCO (–1.78 ±1.62 l/min vs. –0.34 ±2.48 l/min; p = 0.032), COi (–30 ±28% vs. –0.2 ±58%; p = 0.034). Conclusions: In the 5th min the decrease of hemodynamic parameters (ΔSV, ΔCO, COi) was significantly more pronounced in HUTT(+) patients in comparison to the HUTT(–) group.
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Introduction There is no consensus on the length of ECG tracing that should be recorded to represent adequate rate control in patients with atrial fibrillation (AFib). The purpose of the study was to examine whether heart rate measurements based on short-term ECGs recorded at different periods of the day may correspond to the mean heart rate and rate irregularity analyzed from standard 24-hour Holter monitoring. Material and methods The study enrolled 50 consecutive patients with chronic AFib who underwent 24-hour Holter monitoring. Mean heart rate (mHR) and the coefficient of irregularity (CI) were assessed from 5- and 60-minute intervals of Holter recordings in different periods of the day. Results The highest correlation in mean heart rate interval within 24 h was found during a 6-hour sample and in the periods 11.00 AM–12.00 PM, 12 PM–1.00 PM, and 1.00 PM–2.00 PM. With respect to irregularity, only the CI measurements based on a 6-hour interval (7.00 AM–1.00 AM) show a correlation > 0.08 compared to data from the 24-hour recording. Conclusions Only long-term (6-hour) recordings provide a high correlation within 24 h in mean heart rate interval and coefficient of irregularity. It seems that the mean heart rate interval in 1-hour periods between 11 AM and 2 PM might be predictive for 24-hour data. Short time recordings of the coefficient of irregularity of heart rate in AFib patients at this moment are not useful in clinical practice for long-term prognosis of ventricular irregularity.
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For each case of sudden infant and perinatal death, a full review of clinical and epidemiologic data and a complete necropsy study were performed according to the necropsy protocol devised by the Institute of Pathology, University of Milan, Milan, Italy (available at: http://users.unimi.it/~pathol/sids_e.html). Histopathologic examination of unexpected late fetal and neonatal death and SIDS cases allowed us to identify frequent alterations, mainly congenital, of the autonomic nervous system, modulating respiratory, cardiovascular, arousal, and upper digestive activities. The data and arguments presented herein provide a brief survey tending to open, rather than conclude, a far-reaching subject and to motivate medicolegal specialists and pathologists to perform more in-depth study. • Anatomic-pathologic examination • Forensic pathology • Brainstem • Arcuate nucleus hypoplasia • Cardiac conduction system • SIDS • Sudden unexplained perinatal death
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The trigemino-cardiac reflex (TCR) is defined as a sudden onset of parasympathetic dysrhythmia, sympathetic hypotension, apnea or gastric hypermotility during the stimulation of any of the sensory branches of the trigeminal nerve. The sensory nerve endings of the trigeminal nerve send neuronal signals via the Gasserian ganglion to the sensory nucleus of the trigeminal nerve, forming the afferent pathway of the reflex arc. By this physiological response, adjustments of the systemic and cerebral circulations are initiated to change the cerebral blood flow in a manner that is not yet understood. It appears that the cerebrovascular response to hypoxemia is, to a large extent, due to this reflex and is generated by the activation of neurons of the rostral ventrolateral reticular nucleus; the existence of such endogenous neuroprotective strategies may extend beyond the actually known clinical appearance of the TCR and include the prevention of other potential brain injury states as well.
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The trigemino-cardiac reflex (TCR) is defined as the sudden onset of parasympathetic dysrhythmia, sympathetic hypotension, apnoea or gastric hypermotility during stimulation of any of the sensory branches of the trigeminal nerve. In the present review, we summarize the knowledge about the TCR in relation to its two different ways of stimulation: (i) peripheral and (ii) central stimulation. We are the first to differentiate these two ways of occurrence of the TCR in our previous clinical work. From our studies, it seems that these differences are based on the varying autonomic control of the heart initiated either by peripheral or central stimulation. As despite the increasing clinical reports the physiological function of this brainstem reflex has not yet been fully explored, we give here new and important insights into this autonomic brainstem reflex. In addition, we try to give answers to the functional consequence of the different cardiac autonomic control of the TCR. By this physiological response, the adjustments of the systemic and cerebral circulations are initiated to divert blood to the brain or to increase blood flow within it. As a consequence, the striking age-related decline in the occurrence of the TCR seems to be the result of increased arterial stiffness. Our review gives therefore further insight into the potential brainstem circuit of the TCR, the most powerful autonomic reflex known in skull base surgery.
Article
Aim: Trigeminocardicac reflex (TCR), a brainstem reflex, can be manifested in almost all types of surgery in the head and neck region. Patients & methods: Retrospective review of 125 patients operated on cerebellopontine angle (CPA) tumors according to strict inclusion/exclusion criteria. Results: A total of 14 out of 125 patients showed TCR during CPA tumor operation. In total, 29% of those patients presented with a meningioma located exclusively premeatal, but not retromeatal in the CPA. There was significant relationship between meningiomas subgroups and TCR (Barnard test; p < 0.05). Conclusion: Anatomical location may represent an important, but not yet described risk factor for the TCR having therefore an important role in the understanding of the TCR.
Article
The trigeminocardiac reflex (TCR) is a brainstem reflex describing the acute hemodynamic perturbations in neurosurgical patients. The roles of different anatomic locations of this reflex arc on end responses have been found to be variable. In this article, we have highlighted the role and importance of different TCR pathway (peripheral vs central) mechanisms, their manifestations and the various risk factors associated with these. In addition, new insights into various other non-neurosurgical conditions, in special relation to neurointerventional procedures, are also presented in this article. This study is a narrative review based on a PubMed/Google search (from 1 January 1970 to 31 March 2013) on this topic. The common manifestations, such as hypotension and bradycardia, are vagal-dominated responses; however, unusual manifestations, such as hypertension and tachycardia, signify the involvement of the sympathetic nervous system. In addition, there is a complex interaction of the various sensory receptors at the Gasserian ganglion, and this is responsible for the different presentations. There are many surgical as well as nonsurgical risk factors associated with TCR. Interestingly, TCR may affect functional outcome and has been found to be involved in some normal physiological mechanisms, including bruxism. TCR is a complex neurophysiological reflex and there are variable presentations depending upon the peripheral or central stimulation surrounding the Gasserian ganglion. We suggest, for the first time, that if the TCR is initiated at the Gasserian ganglion, it reacts in a different manner from the better-known central or peripheral TCR.