Ease of Noninvasive Measurement of Cardiac Output Coupled With Peak VO2 Determination at Rest and During Exercise in Patients With Heart Failure

doi:10.1016/j.amjcard.2006.08.047

The American Journal of Cardiology

Volume 99, Issue 3, 1 February 2007, Pages 404-405

https://doi.org/10.1016/j.amjcard.2006.08.047 Get rights and content

Peak oxygen consumption (VO₂) is a powerful prognostic predictor of survival in patients with heart failure (HF) because it provides an indirect assessment of a patient’s ability to increase cardiac output (CO). However, many peripheral factors affect VO₂. Inert gas rebreathing using low-concentration soluble and insoluble inert gases can derive CO by the Fick principle. The Innocor rebreathing system uses an oxygen-enriched mixture of an inert soluble gas (0.5% nitrous oxide) and an inert insoluble gas (0.1% sulfur hexafluoride) measured by photoacoustic analyzers over a 5-breath interval. The practicality of this device in measuring CO and VO₂ during exercise was assessed in patients with HF. Ninety-two consecutive exercise tests were prospectively performed in 88 patients with HF using the Innocor system. Incremental bicycle exercise was performed with CO measurements at rest, at 50 W, and at peak exercise. The mean age of the 68 men and 20 women was 54 ± 13 years; 33% had coronary artery disease, and 67% had dilated cardiomyopathy. The mean left ventricular ejection fraction was 24 ± 9%. Patients were able to rapidly learn the rebreathing technique and easily integrate it into the exercise protocol. Eighty-six percent of the tests had successful measurement of metabolic and cardiac output data. Mean CO at rest was 3.5 ± 1.1 L/min and increased to 7.2 ± 2.7 L/min. Mean peak VO₂ was 12.6 ± 4.7 ml/kg/min. A significant linear correlation was observed between peak VO₂ and peak CO (r = 0.64, p <0.0001). In conclusion, combined metabolic stress testing with inert gas rebreathing can be easily performed in patients with HF.

Section snippets

Methods and Results

To assess the practicality and feasibility of the device in measuring CO coupled with VO₂ at rest and during exercise, we prospectively performed 92 consecutive exercise tests in 88 patients with HF. All patients provided written informed consent to the study, which was approved by the local ethics committee. The mean ± SD age of the 68 men and 20 women was 54 ± 13 years; 33% had coronary artery disease, and 67% had dilated cardiomyopathy. The left ventricular ejection fraction averaged 24 ±

Discussion

Our study demonstrated that combined metabolic stress testing with inert gas rebreathing can be easily performed in patients with HF. As would be expected, a moderately good linear correlation was observed between peak VO₂ and peak CO. The widespread clinical application of this technique in the evaluation of patients with HF remains to be determined by a large study with longer follow-up of clinical events to fully determine its prognostic value. However, the ease with which it could be

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2023, Heart and Lung
Citation Excerpt :
One Dyspnea Challenge included measurements of pulmonary gas exchange, which required participants to wear a Hans Rudolph (7450 Series) face mask that covered the nose and mouth and recorded inspired and expired gas concentrations and ventilatory flow (Metamax, Cortex BXB, Leipzig, GER). Central hemodynamics: cardiac output (Q̇), stroke volume (SV) and arteriovenous oxygen difference (C(a-v̅)O2), were measured using non-invasive, signal-morphology impedance cardiography (Physioflow Enduro, Manatec Biomedical, Paris, FR), which has been shown to be reliable in HF and COPD.19,20 All exercise tests included continuous monitoring of electrocardiography (Physioflow Enduro, Manatec Biomedical, Paris, FR), heart rate (HR), and arterial oxygen saturation (SpO2) (RAD-5v Masimo Corp, Irvine, CA, USA).
In heart failure (HF), exertional dyspnea is a common symptom, but validated field-based tests for its measurement are limited. The Dyspnea Challenge is a two-minute uphill treadmill walk designed to measure exertional dyspnea in cardiopulmonary disease.
The purpose of this study was to establish the test-retest reliability of the Dyspnea Challenge in HF and to compare the exercise responses to a group with chronic obstructive pulmonary disease (COPD).
The study was an experimental, single-blind, randomized, multi-site project that recruited individuals with HF (New York Heart Association I-III) and COPD (Global Initiative for Chronic Obstructive Lung Disease II-IV). Participants completed two visits. On the first visit, participants performed two six-minute walk tests (6MWT), followed by two to three Dyspnea Challenges to calculate treadmill speed and gradient. At Visit Two, participants performed two separate Dyspnea Challenges, with one including measures of pulmonary gas exchange and central hemodynamics.
Twenty-one individuals with HF (10 female; 66±11years; ejection fraction:45.3 ± 6.1%; six-minute distance(6MWD) 520 ± 97 m), and 25 COPD (11 female; 68 ± 10 yr; forced expiratory volume in 1 s:47.6 ± 11.5%; 6MWD: 430 ± 101 m). Intraclass correlation coefficients demonstrated excellent test-retest reliability for HF (0.94, P<.01) and COPD (0.95, P<.01). While achieving similar end-exercise exertional dyspnea intensities (P=.60), the HF group walked at a higher average speed (4.2 ± 0.8 vs. 3.5 ± 0.8km·h⁻¹) and gradient (10.3 ± 2.8 vs. 9.6 ± 2.8%) and a greater oxygen uptake (P<.01) and ventilation (P<.01) than those with COPD. While achieving similar cardiac outputs (P=.98), stroke volumes (P=.97), and heart rates (P=.83), those with HF displayed a larger arteriovenous oxygen difference (P<.01), while those with COPD exhibited greater decreases in inspiratory capacity (P=.03), arterial oxygen saturation (P=.02), and breathing reserve (P<.01).
The Dyspnea Challenge is a reliable test-retest measure of exertional dyspnea in HF. Typical to their pathologies, HF seemed limited by an inadequate modulation of cardiac output, while ventilatory constraints hampered those with COPD.
Cardiopulmonary Exercise Testing, Impedance Cardiography, and Reclassification of Risk in Patients Referred for Heart Failure Evaluation: CPX, ICG, and Reclassification of Risk in Heart Failure
2019, Journal of Cardiac Failure
An impaired cardiac output response to exercise is a hallmark of chronic heart failure (HF). We determined the extent to which impedance cardiography (ICG) during exercise in combination with cardiopulmonary exercise test (CPX) responses reclassified risk for adverse events in patients with HF.
CPX and ICG were performed in 1236 consecutive patients (48±15 years) evaluated for HF. Clinical, ICG and CPX variables were acquired at baseline and subjects were followed for the composite outcome of cardiac-related death, hospitalization for worsening HF, cardiac transplantation, and left ventricular assist device implantation. Cox proportional hazards analyses including clinical, noninvasive hemodynamic, and CPX variables were performed to determine their association with the composite endpoint. Net reclassification improvement (NRI) was calculated to quantify the impact of adding hemodynamic responses to a model including established CPX risk markers on reclassifying risk. There were 422 events. Among CPX variables, peak VO₂ and indices of ventilatory inefficiency (VE/VCO₂ slope, oxygen uptake efficiency slope) were significant predictors of risk for adverse events. Among hemodynamic variables, change in cardiac index, peak cardiac time interval, and peak left cardiac work index were the strongest predictors of risk. Having 5 impaired CPX and ICG responses to exercise yielded a sevenfold higher risk for adverse events compared with having no abnormal responses. Combining ICG responses to CPX resulted in NRIs ranging between 0.34 and 0.89, attributable to better reclassification of events.
Cardiac hemodynamics determined by ICG complement established CPX measures in reclassifying risk among patients with HF.
Expanding the clinical classification of heart failure: Inclusion of cardiac function during exercise
2018, Lifestyle in Heart Health and Disease
Despite recent advances in the pathophysiological understanding of heart failure with reduced (HFrEF) or preserved (HFpEF) ejection fraction, there remains an appreciable level of patients whose clinical severity is not optimally classified using traditional paradigms. Although exercise intolerance is a hallmark feature across HF, while also a key marker of patient prognosis that is not related to resting left ventricular ejection fraction, it is not currently routine to objectively assess the functional response of the cardiac system to exercise in the clinical setting. By contrast, accumulating patient-based evidence supports links between impaired exercise cardiac pumping capability and prognosis related to exercise intolerance in HF. Therefore, as a high-priority clinical need, this chapter focuses on discussing the science and real-world clinical value of routinely assessing exercise cardiac pumping capability in HF, which will advance the pathophysiological understanding of exercise intolerance in HF while also strengthening the traditional model used for the clinical classification of HF patients.
Hemodynamics should be the primary approach to diagnosing, following, and managing pulmonary arterial hypertension
2015, Canadian Journal of Cardiology
Pulmonary arterial hypertension (PAH) is a highly morbid cardiopulmonary disease characterized by plexogenic pulmonary arteriole remodelling. Importantly, PAH severity correlates inversely with cardiac output and directly with pulmonary vascular resistance and right atrial pressure, illustrating the importance of accurately measured hemodynamics to define the clinical profile of patients. Currently available noninvasive technology offers only hemodynamic estimates. In contrast, right heart catheterization is the principle diagnostic procedure in PAH and is required to: (1) definitively exclude alternative pulmonary vascular diseases; and (2) quantify hemodynamics at baseline, after vasoreactivity testing, or in response to therapy to prognosticate outcome and guide therapeutic escalation.
L’hypertension artérielle pulmonaire (HTAP), une maladie cardiopulmonaire, est un état très morbide qui est caractérisé par le remodelage plexogène des artérioles pulmonaires. Notamment, la gravité de la HTAP corrèle inversement avec le débit cardiaque et directement avec la résistance vasculaire pulmonaire et la pression auriculaire droite, ce qui illustre l’importance de mesurer avec précision l’hémodynamique pour définir le profil clinique des patients. La technologie non effractive actuellement disponible offre seulement des estimations hémodynamiques. En revanche, le cathétérisme cardiaque droit est la procédure diagnostique de principe de la HTAP qui est requise pour : 1) exclure définitivement les autres maladies vasculaires pulmonaires; 2) quantifier l’hémodynamique au début, après le test de vasoréactivité ou en réponse au traitement pour pronostiquer l’évolution et guider l’escalade thérapeutique.
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2014, Journal of Cardiac Failure
Mixed venous saturation (MVS) obtained from the distal pulmonary artery (PA) during Swan-Ganz catheterization is the criterion standard for calculating cardiac output (CO) and cardiac index (CI) with the use of the Fick method. We think that calculating CI with the use of central venous saturation (CVS) instead of PA-MVS is both feasible and accurate. Earlier studies were small, enrolled heterogeneous patient populations, and resulted in inconsistent findings.
All patients undergoing right heart catheterization from January 2011 to January 2012 in our catheterization lab with simultaneous measurements of MVS obtained from the distal PA and CVS obtained from the superior vena cava (SVC) or right atrium (RA) were included. Out of the 902 patients enrolled, we excluded patients (n = 50) who had known cardiac shunt or dialysis fistula, had duplicate medical records, or were septic. We calculated the CI with the use of the assumed Fick method using both MVS (criterion standard) and CVS (SVC or RA saturations) in the remaining 852 patients. We measured the correlation and the agreement between the 2 methods with the use of the Pearson correlation coefficient and Bland-Altman analysis.
Totals of 112 patients with simultaneous PA and RA saturation measurements (group I) and 740 patients with simultaneous PA and SVC saturation measurements (group II) were included. We found an excellent linear correlation between SVC and PA saturation (r = 0.928) and between RA and PA saturation (r = 0.95). There was also an excellent correlation between CI calculated with the use of PA saturation and CI calculated with the use of SVC (r = 0.87) or RA (r = 0.93) saturation. The mean bias of CVS-derived CI compared with MVS-derived CI (criterion standard) was −0.1 (95% limits of agreement [LOA] −1 to +0.77) in the SVC group and −0.006 (LOA −0.68 to +0.69) in the RA group. Patients with low CI had stronger correlation and smaller bias between the 2 methods compared with those with normal or high CI. The presence of baseline hypoxemia, valvular heart disease, or acute coronary syndrome had no significant effect on the correlation or the bias between the 2 methods.
In cardiac patients, CVS can be used as a surrogate to true MVS in the calculation of CI. This method is readily available in patients who have central venous access, and may aid in early goal-directed treatment when cardiogenic shock is suspected.
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After the Fontan procedure patients are at risk for reduced quality of life (QoL) and cognitive function. We aimed to assess these important factors in Danish Fontan patients and to compare the results with a group of healthy controls.
All Fontan patients living in Denmark were identified and invited to participate. QoL was evaluated using the Pediatric Quality of Life Inventory (PedsQL) version 4.0 generic core module in patients < 16 years and the Short Form 36 questionnaire (SF-36) in patients ≥ 16 years. Cognitive function was evaluated in all patients ≥ 6 years using the Quick Test of Cognitive Speed. To evaluate if QoL correlated with exercise capacity, patients performed a symptom-limited bicycle test.
158 of 179 eligible patients (88%) consented to participate. Median age was 13.9 years (IQR: 10.2–19.3). PedsQL scores increased with age but were significantly lower among patients than among controls. SF-36 physical scores were significantly lower in patients compared to controls while psychosocial scores were similar. Cognitive speed was significantly reduced in patients at all ages compared to controls. No significant difference in PedsQL-/SF-36 scores or cognitive speed was found between hypoplastic left heart syndrome (HLHS) and non-HLHS Fontan patient. PedsQL-/SF-36 scores in patients ≥ 10 years correlated significantly to cognitive speed but not to peak exercise capacity.
QoL is reduced in Fontan children compared to their healthy counterparts whereas in patients ≥ 16 years only physical, but not psychosocial QoL is reduced. Cognitive speed was significantly lower in patients at all ages compared to controls.

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Heart failureEase of Noninvasive Measurement of Cardiac Output Coupled With Peak VO2 Determination at Rest and During Exercise in Patients With Heart Failure

Section snippets

Methods and Results

Discussion

Am Heart J

J Am Coll Cardiol

J Am Coll Cardiol

J Am Coll Cardiol

J Am Coll Cardiol

Correlates and prognostic implication of exercise capacity in chronic congestive heart failure

Am J Cardiol

Value of peak exercise oxygen consumption for optimal timing of cardiac transplantation in ambulatory patients with heart failure

Circulation

Heart failure
Ease of Noninvasive Measurement of Cardiac Output Coupled With Peak VO₂ Determination at Rest and During Exercise in Patients With Heart Failure