Article

The effects of inflammation on heart rate and rhythm in a canine model of cardiac surgery.

Division of Cardiothoracic Surgery, Washington University School of Medicine, Barnes Jewish Hospital, St Louis, Missouri 63110, USA.
Heart rhythm: the official journal of the Heart Rhythm Society (impact factor: 4.56). 03/2012; 9(3):432-9. DOI:10.1016/j.hrthm.2011.09.074 pp.432-9
Source: PubMed

ABSTRACT Heart rate (HR) and rhythm disturbances are common after cardiac surgery. This study tests the hypothesis that the inflammation caused by cardiac surgery is an underlying mechanism for postoperative changes in HR, rhythm, and HR variability (HRV).
Normal canines (n = 6 per group) were divided into 4 groups: (1) anesthesia, (2) sternotomy and pericardiotomy, (3) atriotomy, and (4) corticosteroids combined with an atriotomy. Continuous electrocardiographic recordings were done preoperatively and for 3 postoperative days. Electrophysiologic testing was done at the initial and terminal surgeries. C-reactive protein level was assessed at each study day, and tissue myeloperoxidase activity was assessed at the terminal study. Measurements of HRV were determined daily to detect changes in autonomic tone. Postoperatively, the HR increased in the pericardiotomy (P = .0005) and atriotomy (P = .001) groups and HRV decreased in both the groups. No significant change occurred in either the HR or HRV in the anesthesia (P = .52) and steroid (P = .16) groups. HRV (triangular index) on postoperative day 3 was correlated with the tissue myeloperoxidase levels (r = -.83; P = .0004). Autonomic blockade with atropine and esmolol resulted in an HR and HRV that were not significantly different between groups. Atrial premature beats occurred postoperatively in the all the groups except the anesthesia group and were independent of the degree of inflammation.
Cardiac surgery increases the postoperative HR by reducing HRV, mostly because of a reduction in vagal tone. Furthermore, the magnitude of these changes is dependent on the degree of inflammation and is normalized by corticosteroids.

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  • Article: Impairment of cardiovascular autonomic control in patients early after cardiac surgery.
    R Bauernschmitt, H Malberg, N Wessel, B Kopp, E U Schirmbeck, R Lange
    [show abstract] [hide abstract]
    ABSTRACT: Impairment of the baroreceptor reflex activity reflects an alteration of the autonomous regulation of the cardiovascular system and has proven to predict fatal outcome in patients after acute myocardial infarction. The following study was performed to analyse the baroreceptor sensitivity, heart rate variability and blood pressure variability in patients early after coronary surgery. Twenty-five male patients undergoing coronary artery bypass were examined in a prospective study; normal values were obtained from healthy volunteers. Arterial pressure signals were recorded from a radial artery catheter for 30 min preoperatively and in short intervals after surgery. Mechanical manipulations and pharmacological interventions were avoided during the sampling periods. Baroreflex function was calculated according to the dual sequence method, heart rate variability and blood pressure variability were calculated including nonlinear methods. Initial values of the patients did not differ from healthy volunteers. The strength of baroreflex sensitivity (increase in blood pressure causing a synchronous decrease of heart rate) is low 2 h postoperatively. The number of delayed tachycardic changes of heart rate, which are caused by sympathetic activation, is only moderately reduced as compared to values obtained from healthy volunteers. Heart rate variability is widely unchanged as compared to preoperative values; blood pressure variability showed an increase of low-frequency components, again indicating sympathetic predominance. Nonlinear analyses revealed reduced system complexity at the beginning of the postoperative course. Obviously, there is a vagal suppression 20 h after surgery, while the sympathetic tonus works in a normal range. This unbalanced interaction of the autonomous systems is similar to findings in patients after myocardial infarction. The predictive value of these markers has to be elucidated in further clinical studies.
    European Journal of Cardio-Thoracic Surgery 04/2004; 25(3):320-6. · 2.55 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

3 postoperative days
 
anesthesia group
 
Atrial premature beats
 
C-reactive protein level
 
Continuous electrocardiographic recordings
 
Electrophysiologic testing
 
Heart rate
 
HR variability
 
HRV
 
postoperative changes
 
postoperative day 3
 
postoperative HR
 
Postoperatively
 
rhythm disturbances
 
study day
 
terminal surgeries
 
tissue myeloperoxidase activity
 
tissue myeloperoxidase levels
 
triangular index
 
vagal tone