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Mid-ventricular short axis slices in end-diastole (ED) and end-systole (ES) during rest and exercise with the corresponding 4-chamber (4 ch) view to illustrate the location of the slice. The solid line indicates delineations for total heart volume. In the exercise images, the dashed line shows the total heart volume delineation copied from the corresponding resting image. The right ventricular volume is decreased whereas the left ventricle remains unchanged.
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The effects on left and right ventricular (LV, RV) volumes during physical exercise remains controversial. Furthermore, no previous study has investigated the effects of exercise on longitudinal contribution to stroke volume (SV) and the outer volume variation of the heart. The aim of this study was to determine if LV, RV and total heart volumes (T...
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Background: Although compressed sensing (CS) accelerated cine holds immense potential to replace conventional cardiovascular magnetic resonance (CMR) cine, how to use CS-based cine appropriately during clinical CMR examinations still needs exploring. Methods: A total of 104 patients (46.5 ± 17.1 years) participated in this prospective study. For ea...
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Background:
Breath-hold (BH) requirement remains the limiting factor on the spatio-temporal resolution and coverage of the cine balanced steady-state free precession (bSSFP) cardiovascular magnetic resonance (CMR) imaging. In this prospective two-center clinical trial, we validated the performance of a respiratory triggered (RT) bSSFP cine sequenc...
Background:
Conventional 2D inversion recovery (IR) and phase sensitive inversion recovery (PSIR) late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) have been widely incorporated into routine CMR for the assessment of myocardial viability. However, reliable suppression of fat signal, and increased isotropic spatial resolutio...
Citations
... The predominant posteriorly accumulated LWD, but higher anterior ΔLWD increase, further reflects a global increase in pulmonary perfusion during exercise. The decrease in left ventricular end systolic volume during supine exercise are in line with previous findings by Steding-Ehrenborg et al. 34 Steding-Ehrenborg et al did however, in contrast to this study, not observe differences in end diastolic volume. Their MRI exercise protocol was performed with one-legged knee extensions with images acquired at breath-hold, which may explain this difference. ...
Purpose
Exercise‐induced dyspnea caused by lung water is an early heart failure symptom. Dynamic lung water quantification during exercise is therefore of interest to detect early stage disease. This study developed a time‐resolved 3D MRI method to quantify transient lung water dynamics during rest and exercise stress.
Methods
The method was evaluated in 15 healthy subjects and 2 patients with heart failure imaged in transitions between rest and exercise, and in a porcine model of dynamic extravascular lung water accumulation through mitral regurgitation (n = 5). Time‐resolved images were acquired at 0.55T using a continuous 3D stack‐of‐spirals proton density weighted sequence with 3.5 mm isotropic resolution, and derived using a motion corrected sliding‐window reconstruction with 90‐s temporal resolution in 20‐s increments. A supine MRI‐compatible pedal ergometer was used for exercise. Global and regional lung water density (LWD) and percent change in LWD (ΔLWD) were automatically quantified.
Results
A ΔLWD increase of 3.3 ± 1.5% was achieved in the animals. Healthy subjects developed a ΔLWD of 7.8 ± 5.0% during moderate exercise, peaked at 16 ± 6.8% during vigorous exercise, and remained unchanged over 10 min at rest (−1.4 ± 3.5%, p = 0.18). Regional LWD were higher posteriorly compared the anterior lungs (rest: 33 ± 3.7% vs 20 ± 3.1%, p < 0.0001; peak exercise: 36 ± 5.5% vs 25 ± 4.6%, p < 0.0001). Accumulation rates were slower in patients than healthy subjects (2.0 ± 0.1%/min vs 2.6 ± 0.9%/min, respectively), whereas LWD were similar at rest (28 ± 10% and 28 ± 2.9%) and peak exercise (ΔLWD 17 ± 10% vs 16 ± 6.8%).
Conclusion
Lung water dynamics can be quantified during exercise using continuous 3D MRI and a sliding‐window image reconstruction.
... Invasive pressure-volume (PV) loops are gold standard to assess hemodynamic function and cardiac performance [1] and can provide information on both load-dependent and load-independent parameters such as myocardial contractility, ventricular efficiency, and arterial elastance [2]. Thus, PV loops may provide additional information in patients with decreased cardiac function and potentially explain the enhanced cardiac function seen in endurancetrained (ET) athletes during exercise [3][4][5][6][7][8]. However, measuring PV loops during exercise has been challenging, likely due to the invasive nature previously needed to acquire the measurements. ...
... This is the first study to show feasibility of non-invasive PV loops using CMR during exercise for hemodynamic assessment, adding to prior work by Seemann et al. [9] and Sjöberg et al. [10]. The physiological exercise response of LV volumes are in line with previous studies, demonstrating increased LVSV through increased LVEDV and decreased LVESV in ET, and increased LVSV through maintained or decreased LVEDV and decreased LVESV in healthy volunteers [3,5,6]. Furthermore, the physiological exercise response of hemodynamics is also in line with previous studies, demonstrating decreased SVR and increased contractility [30,31], indicating that non-invasively obtained PV loops during exercise can be used to assess hemodynamic changes. ...
Introduction
Pressure-volume (PV) loops can be used to assess both load-dependent and load-independent measures of cardiac hemodynamics. However, analysis of PV loops during exercise is challenging as it requires invasive measures. Using a novel method, it has been shown that left ventricular (LV) PV loops at rest can be obtained non-invasively from cardiac magnetic resonance imaging (CMR) and brachial pressures. Therefore, the aim of this study was to assess if LV PV loops can be obtained non-invasively from CMR during exercise to assess cardiac hemodynamics.
Methods
Thirteen endurance trained (ET; median 48 years [IQR 34–60]) and ten age and sex matched sedentary controls (SC; 43 years [27–57]) were included. CMR images were acquired at rest and during moderate intensity supine exercise defined as 60% of expected maximal heart rate. Brachial pressures were obtained in conjunction with image acquisition.
Results
Contractility measured as maximal ventricular elastance (Emax) increased in both groups during exercise (ET: 1.0 mmHg/ml [0.9–1.1] to 1.1 mmHg/ml [0.9–1.2], p<0.01; SC: 1.1 mmHg/ml [0.9–1.2] to 1.2 mmHg/ml [1.0–1.3], p<0.01). Ventricular efficiency (VE) increased in ET from 70% [66–73] at rest to 78% [75–80] (p<0.01) during exercise and in SC from 68% [63–72] to 75% [73–78] (p<0.01). Arterial elastance (EA) decreased in both groups (ET: 0.8 mmHg/ml [0.7–0.9] to 0.7 mmHg/ml [0.7–0.9], p<0.05; SC: 1.0 mmHg/ml [0.9–1.2] to 0.9 mmHg/ml [0.8–1.0], p<0.05). Ventricular-arterial coupling (EA/Emax) also decreased in both groups (ET: 0.9 [0.8–1.0] to 0.7 [0.6–0.8], p<0.01; SC: 1.0 [0.9–1.1] to 0.7 [0.7–0.8], p<0.01).
Conclusions
This study demonstrates for the first time that LV PV loops can be generated non-invasively during exercise using CMR. ET and SC increase ventricular efficiency and contractility and decrease afterload and ventricular-arterial coupling during moderate supine exercise. These results confirm known physiology. Therefore, this novel method is applicable to be used during exercise in different cardiac disease states, which has not been possible non-invasively before.
... Dobutamine dose was set as 5-10 µg/kg/min and adjusted every 2 min, until reaching a HR ∼60% higher than the one at rest. This target HR was chosen in order to achieve HR in the range of those from previous studies on stress testing with MRI (31)(32)(33)(34). HR was monitored continuously throughout the study and blood pressures were measured at rest and after dobutamine. ...
The total kinetic energy (KE) of blood can be decomposed into mean KE (MKE) and turbulent KE (TKE), which are associated with the phase-averaged fluid velocity field and the instantaneous velocity fluctuations, respectively. The aim of this study was to explore the effects of pharmacologically induced stress on MKE and TKE in the left ventricle (LV) in a cohort of healthy volunteers. 4D Flow MRI data were acquired in eleven subjects at rest and after dobutamine infusion, at a heart rate that was ∼60% higher than the one in rest conditions. MKE and TKE were computed as volume integrals over the whole LV and as data mapped to functional LV flow components, i.e., direct flow, retained inflow, delayed ejection flow and residual volume. Diastolic MKE and TKE increased under stress, in particular at peak early filling and peak atrial contraction. Augmented LV inotropy and cardiac frequency also caused an increase in direct flow and retained inflow MKE and TKE. However, the TKE/KE ratio remained comparable between rest and stress conditions, suggesting that LV intracavitary fluid dynamics can adapt to stress conditions without altering the TKE to KE balance of the normal left ventricle at rest.
... Reliability of LV volumetric and mass measurements between all completed RT short-axis stack constructions was tested using ICC to further evaluate necessary image acquisition time. For reliability during exercise, only LVM was compared to ECG-gated images as volumes, but not mass, were expected to differ between these two physiological conditions 17,33,34 . Similarly, RT CMR images analyzed at end inspiration were not used for volumes as ventricular volumes may differ depending on the respiratory state [17][18][19] . ...
Exercise cardiovascular magnetic resonance (CMR) can unmask cardiac pathology not evident at rest. Real-time CMR in free breathing can be used, but respiratory motion may compromise quantification of left ventricular (LV) function. We aimed to develop and validate a post-processing algorithm that semi-automatically sorts real-time CMR images according to breathing to facilitate quantification of LV function in free breathing exercise. A semi-automatic algorithm utilizing manifold learning (Laplacian Eigenmaps) was developed for respiratory sorting. Feasibility was tested in eight healthy volunteers and eight patients who underwent ECG-gated and real-time CMR at rest. Additionally, volunteers performed exercise CMR at 60% of maximum heart rate. The algorithm was validated for exercise by comparing LV mass during exercise to rest. Respiratory sorting to end expiration and end inspiration (processing time 20 to 40 min) succeeded in all research participants. Bias ± SD for LV mass was 0 ± 5 g when comparing real-time CMR at rest, and 0 ± 7 g when comparing real-time CMR during exercise to ECG-gated at rest. This study presents a semi-automatic algorithm to retrospectively perform respiratory sorting in free breathing real-time CMR. This can facilitate implementation of exercise CMR with non-ECG-gated free breathing real-time imaging, without any additional physiological input.
... Several investigators demonstrated exercise stress CMR using an in-room treadmill system followed by a rapid transfer of the subject into the scanner with subsequent imaging [7][8][9][10][11][12]. On the other hand, MR-compatible equipment enabling imaging at 1.5 tesla (T) while the patient is at peak exercise stress was shown to be feasible for the evaluation of blood flow dynamics and ventricular function in healthy volunteers [13][14][15][16][17][18][19][20]. Another proof-of-concept study reported on a 3T compatible ergometer, which allowed the assessment of cardiac morphology and function in healthy subjects [6]. ...
Background:
Cardiac magnetic resonance imaging (CMR) remains underutilized as an exercise imaging modality, mostly because of the limited availability of MR-compatible exercise equipment. This study prospectively evaluates the clinical feasibility of a newly developed MR-conditional pedal ergometer for exercise CMR METHODS: Ten healthy volunteers (mean age 44 ± 16 years) and 11 patients (mean age 60 ± 9 years) with known or suspected coronary artery disease (CAD) underwent rest and post-exercise cinematic 3T CMR. Visual analysis of wall motion abnormalities (WMA) was rated by 2 experienced radiologists, and volumes and ejection fractions (EF) were determined. Image quality was assessed by a 4-point Likert scale for visibility of endocardial borders.
Results:
Median subjective image quality of real-time Cine at rest was 1 (IQR 1-2) and 2 (IQR 2-2.5) for post-exercise real-time Cine (p = 0.001). Exercise induced a significant increase in heart rate (62 [62-73] to 111 [104-143] bpm, p < 0.0001). Stroke volume and cardiac index increased from resting to post-exercise conditions (85 ± 21 to 101 ± 19 mL and 2.9 ± 0.7 to 6.6 ± 1.9 L/min/m², respectively; both p < 0.0001), driven by a reduction in end-systolic volume (55 ± 20 to 42 ± 21 mL, p < 0.0001). Patients (2/11) with inducible regional WMA at high-resolution post-exercise cine imaging revealed significant coronary artery stenosis in subsequently performed invasive coronary angiography.
Conclusion:
Exercise-CMR using our newly developed 3T MR-conditional pedal ergometer is clinically feasible. Imaging of both cardiac response and myocardial ischemia, triggered by dynamic stress, is rapidly conducted while the patient is near their peak heart rate.
... Inter-scan reproducibility was not assessed with this study, but has been demonstrated in our institution previously in an Ex-CMR study assessing biventricular volumes using a similar retrospectively gated, respiratory navigated short axis cine sequence [42]. As expected, and demonstrated in prior Ex-CMR studies [16,31,46,47], image quality decreases with increasing exercise intensity, however our study still demonstrated good intra-and inter-observer reproducibility during moderate intensity exercise. ECG interference was encountered in one patient, early in the study, such that miss-triggering occurred at moderate exercise intensity. ...
Purpose:
Exercise cardiovascular magnetic resonance (Ex-CMR) typically requires complex post-processing or transient exercise cessation, decreasing clinical utility. We aimed to demonstrate the feasibility of assessing biventricular volumes and great vessel flow during continuous in-scanner Ex-CMR, using vendor provided Compressed SENSE (C-SENSE) sequences and commercial analysis software (Cvi42).
Methods:
12 healthy volunteers (8-male, age: 35 ± 9 years) underwent continuous supine cycle ergometer (Lode-BV) Ex-CMR (1.5T Philips, Ingenia). Free-breathing, respiratory navigated C-SENSE short-axis cines and aortic/pulmonary phase contrast magnetic resonance (PCMR) sequences were validated against clinical sequences at rest and used during low and moderate intensity Ex-CMR. Optimal PCMR C-SENSE acceleration, C-SENSE-3 (CS3) vs C-SENSE-6 (CS6), was further investigated by image quality scoring. Intra-and inter-operator reproducibility of biventricular and flow indices was performed.
Results:
All CS3 PCMR image quality scores were superior (p < 0.05) to CS6 sequences, except pulmonary PCMR at moderate exercise. Resting stroke volumes from clinical PCMR sequences correlated stronger with CS3 than CS6 sequences. Resting biventricular volumes from CS3 and clinical sequences correlated very strongly (r > 0.93). During Ex-CMR, biventricular end-diastolic volumes (EDV) remained unchanged, except right-ventricular EDV decreasing at moderate exercise. Biventricular ejection-fractions increased at each stage. Exercise biventricular cine and PCMR stroke volumes correlated very strongly (r ≥ 0.9), demonstrating internal validity. Intra-observer reproducibility was excellent, co-efficient of variance (COV) < 10%. Inter-observer reproducibility was excellent, except for resting right-ventricular, and exercise bi-ventricular end-systolic volumes which were good (COV 10-20%).
Conclusion:
Biventricular function, aortic and pulmonary flow assessment during continuous Ex-CMR using CS3 sequences is feasible, reproducible and analysable using commercially available software.
... Animal studies initially showed that LA relaxation rate, reservoir volume, and mean and V-wave pressures increase during exercise (198). In humans, the LA volume response to exercise remains unclear; several studies using two-dimensional (2D) volumes or diameters have shown increased maximal and stable minimal LA size (199)(200)(201), whereas others demonstrate the opposite (166,202,203), which may reflect differences in study design. However, both perspectives support an expanded reservoir volume proportionate to increases in SV (59) during exercise along with reservoir phase LA strain (172,195). ...
With each heartbeat, the right ventricle (RV) inputs blood into the pulmonary vascular (PV) compartment which conducts blood through the lungs at low pressure and concurrently fills the left atrium (LA) for output to the systemic circulation. This overall hemodynamic function of the integrated RV-PV-LA unit is determined by complex interactions between the components that vary over the cardiac cycle but are often assessed in terms of mean pressure and flow. Exercise challenges these hemodynamic interactions as cardiac filling increases, stroke volume augments, and cycle length decreases, with PV pressures ultimately increasing in association with cardiac output. Recent cardio-pulmonary exercise hemodynamic studies have enriched the available data from healthy adults, yielded insight into the underlying mechanisms which modify the PV pressure-flow relationship, and better delineated the normal limits of healthy responses to exercise. This review will examine hemodynamic function of the RV-PV-LA unit using the 2-element Windkessel model for the pulmonary circulation. It will focus on acute PV and LA responses that accommodate increased RV output during exercise, including PV recruitment and distension and LA reservoir expansion, and the integrated mean pressure-flow response to exercise in healthy adults. Finally, it will consider how these responses may be impacted by age-related remodeling and modified by sex-related cardio-pulmonary differences. Studying the determinants and recognizing the normal limits of PV pressure-flow relations during exercise will improve our understanding of cardio-pulmonary mechanisms that facilitate or limit exercise.
... In addition, despite the presence of observations regarding the effect of alterations in heart rate on LV volumes, these studies were done mainly among men and did not provide viable information on the effect of heart rate increase on heart chamber volumes among women. [2][3][4][11][12][13][14][15][16][17][18] CCTA is nowadays widely used for the assessment of CAD. 19 The same imaging study may provide in addition data on the volumes of each of the cardiac chambers, including the LA, RV, and RA, which can be valuable. ...
... Investigations of the effect of increased heart rate on LV volume during physical exercise as opposed to resting are numerous but are mostly performed on men only. [12][13][14][15][16][17][18][21][22][23] This study, which contains a relatively Adjusted to age and variables, which had p < 0.2 in univariate analysis. Hypertension, diabetes mellitus, hyperlipidemia, overweight, chronic obstructive pulmonary disease, anemia, smoking, and b-blocker were considered as potential confounders for inclusion in multivariate analysis. ...
Background: Currently, normal values of the cardiac chambers' volumes are adjusted only for gender and body surface area (BSA). We aim to investigate the association between the heart rate and the volume of each of the four cardiac chambers using cardiac-gated computed tomography angiography (CCTA).
Methods: A total of 350 consecutive patients without known cardiac diseases or significant (>50%) stenosis undergoing CCTA between January 2009 and June 2014 for suspected coronary artery disease were included. Cardiac chamber volumes adjusted to BSA were calculated using automated model-based segmentation analysis software of the CCTA data and correlated with patients' mean heart rate during the scan.
Results: There were 240 men and 110 women, median interquartile range age was 55 years (47–61). Women were older 59.0 years (53.7–64) versus 52.0 years (45.0–59.0), had higher prevalence of hyperlipidemia, diabetes mellitus, anemia, and hypothyroidism, and higher median heart rates 64.0 (59.7–66.0) versus 60.0 (55.0–65.0) (p < 0.001). Men had a negative correlation between the volume of each cardiac chamber and the heart rate [rage_adj = (−0.4)–(−0.27), p < 0.001 for all], whereas such a correlation was not found in women. The multivariate analysis showed that a decrease of five beats per minute was associated with an increase of 4%–5% in volume of each chamber in men. There was no such association among females.
Conclusions: Lower heart rate is associated with an increase of each cardiac chamber volume by CCTA in men. This association is not found in women. More extensive studies are required to further elaborate on these gender differences.
... Studies utilising commercially produced cycle ergometers followed in 1998 with the use of the Lode BV MR compatible ergometer (Fig. 3) on a 1.5 T CMR scanner [60]. Whilst the majority of Ex-CMR cycle ergometer studies use this system [29,54,55,, some institutions have created custom made CMR compatible cycle ergometers [25,81,82]. Other approaches include the supine CMR compatible 'stepper' ergometer, that utilises an up/down motion, such as the Lode BV up/down ergometer [83][84][85], Ergospect cardio-stepper [86] and custom built supine steppers as demonstrated in Fig. 4 [87]. ...
... Cycle ergometer Ex-CMR ventricular volume assessment has progressed from imaging during exercise cessation with breath holding [25,67,[70][71][72]81], breath holding during exercise [82,86], free breathing with exercise cessation [54,64,66], to free breathing during continuous exercise [29,83]. Initial studies utilised turbo field echo planar imaging (EPI) with retrospective gating to acquire short axis cine imaging for biventricular volumes during exercise [67,70,71]. ...
... Initial studies utilised turbo field echo planar imaging (EPI) with retrospective gating to acquire short axis cine imaging for biventricular volumes during exercise [67,70,71]. Subsequent studies using retrospective ECG gating have used balanced steady state free precision (bSSFP) sequences [25,81,82,88,89]. Recently, an Ex-CMR study used a 3 T scanner to assess LV volumes similarly used bSSFP sequences to acquire 4 chamber and 2-chamber cines to calculate LV function via Simpson's bi-plane method [86]. ...
Stress cardiac imaging is the current first line investigation for coronary artery disease diagnosis and decision making and an adjunctive tool in a range of non-ischaemic cardiovascular diseases. Exercise cardiovascular magnetic resonance (Ex-CMR) has developed over the past 25 years to combine the superior image qualities of CMR with the preferred method of exercise stress. Presently, numerous exercise methods exist, from performing stress on an adjacent CMR compatible treadmill to in-scanner exercise, most commonly on a supine cycle ergometer. Cardiac conditions studied by Ex-CMR are broad, commonly investigating ischaemic heart disease and congenital heart disease but extending to pulmonary hypertension and diabetic heart disease. This review presents an in-depth assessment of the various Ex-CMR stress methods and the varied pulse sequence approaches, including those specially designed for Ex-CMR. Current and future developments in image acquisition are highlighted, and will likely lead to a much greater clinical use of Ex-CMR across a range of cardiovascular conditions.
... Excessive motion during exercise however poses a challenge in image acquisition. As a result, investigators have resorted to acquire images following transient cessation of exercise (17), during breath-holds (6,17,18) or using ungated real-time cine imaging (19). Reconstruction of a short axis stack for volumetric analysis from ungated realtime imaging, however, involves complex post-processing analysis in addition to a requirement for bespoke in-house software (19). ...
... Previously, image acquisition techniques using the MRI cycle ergometer have either involved a brief period of exercise cessation (17) or required a breath-hold protocol (6,18) in order to reduce excessive motion artefacts and avoid poor ECG signal. Ungated real-time CMR imaging (19,23,24) has been a method that enabled cine images to be acquired during continuous exercise. ...
... The results of this present study are in line with previous studies of supine exercise, showing a decrease in LV (24,36) and RV (18,23,37) EDVs, particularly during later stages of exercise. Similar to previous exCMR studies, we demonstrated no significant rise in stroke volume with exercise (38). ...
Background:
Cardiovascular magnetic resonance (CMR) image acquisition techniques during exercise typically requires either transient cessation of exercise or complex post-processing, potentially compromising clinical utility. We evaluated the feasibility and reproducibility of a navigated image acquisition method for ventricular volumes assessment during continuous physical exercise.
Methods:
Ten healthy volunteers underwent supine cycle ergometer (Lode) exercise CMR on two separate occasions using a free-breathing, multi-shot, navigated, balanced steady-state free precession cine pulse sequence. Images were acquired at 3-stages, baseline and during steady-state exercise at 55% and 75% maximal heart rate (HRmax), based on a prior supine cardiopulmonary exercise test. Intra-and inter-observer variability and inter-scan reproducibility were derived. Clinical feasibility was tested in a separate cohort of patients with severe mitral regurgitation (n=6).
Results:
End-diastolic volume (EDV) of both LV and RV decreased during exercise at 55% and 75% HRmax, although a reduction in RVEDV index was only observed at 75% HRmax. Ejection fractions (EF) for both ventricles were significantly higher at 75% HRmax compared to their respective baselines (LVEF 68%±3% vs. 58%±5%, P=0.001; RVEF 66%±4% vs. 58%±7%, P=0.02). Intra-observer and inter-observer reproducibility of LV parameters was excellent at all 3-stages. Although measurements of RVESV were more variable during exercise, the reproducibility of both RVEF and RV cardiac index was excellent (CV <10%). Inter-scan LV and RV ejection fraction were highly reproducible at all 3 stages, although inter-scan reproducibility of indexed RVESV was only moderate. The protocol was well tolerated by all patients.
Conclusions:
Exercise CMR using a free-breathing, multi-shot, navigated cine imaging method allows simultaneous assessment of left and right ventricular volumes during continuous exercise. Intra- and inter-observer reproducibility were excellent. Inter-scan LV and RV ejection fraction were also highly reproducible.
