Reference Values for Peak Exercise Cardiac Output in Healthy Individuals

BACKGROUND: Cardiac output (Q\u2d9) is a key parameter in the assessment of cardiac function, its measurement being crucial for the diagnosis, treatment, and prognostic evaluation of all heart diseases. Until recently, Q\u2d9 determination at peak exercise has been possible through invasive methods, so that normal values were obtained in studies based on small populations. METHODS: Nowadays, peak Q\u2d9 can be measured noninvasively by means of the inert gas rebreathing (IGR) technique. The present study was undertaken to provide reference values for peak Q\u2d9 in the normal general population and to obtain a formula able to estimate peak exercise Q\u2d9 from measured peak oxygen uptake (V\u2d9o2). RESULTS: We studied 500 normal subjects (age, 44.9 \ub1 1.5 years; range, 18-77 years; 260 men, 240 women) who underwent a maximal cardiopulmonary exercise test with peak Q\u2d9 measurement by IGR. In the overall study sample, peak Q\u2d9 was 13.2 \ub1 3.5 L/min (men, 15.3 \ub1 3.3 L/min; women, 11.0 \ub1 2.0 L/min; P < .001) and peak V\u2d9o2 was 95% \ub1 18% of the maximum predicted value (men, 95% \ub1 19%; women, 95% \ub1 18%). Peak V\u2d9o2 and peak Q\u2d9 progressively decreased with age (R2, 0.082; P < .001; and R2, 0.144; P < .001, respectively). The V\u2d9o2-derived formula to measure Q\u2d9 at peak exercise was (4.4 7 peak V\u2d9o2) + 4.3 in the overall study cohort, (4.3 7 peak V\u2d9o2) + 4.5 in men, and (4.9 7 peak V\u2d9o2) + 3.6 in women. CONCLUSIONS: The simultaneous measurement of Q\u2d9 and V\u2d9o2 at peak exercise in a large sample of healthy subjects provided an equation to predict peak Q\u2d9 from peak V\u2d9o2 values

Chronotropic Incompentence and Functional Capacity in CHF

SUMMARY Aim: To assess the effect of chronotropic incompetence on functional capacity in chronic heart failure (CHF) patients, as evaluated as NYHA and peak oxygen consumption (pVO2), focusing on the presence and dose of β-blocker treatment. Methods: Nine hundred and sixty-seven consecutive CHF patients were evaluated, 328 of whom were discarded because they failed to meet the study criteria. Of the 639 analyzed, 90 were not treated with β-blockers whereas the other 549 were. The latter were further subdivided in high (n = 184) and low (n = 365) β-blockers daily dose group in accordance with an arbitrary cut-off of 25 mg for carvedilol and of 5 mg for bisoprolol. Failure to achieve 80% of the percentage of maximum age predicted peak heart rate (%Max PHR) or of HR reserve (%HRR) constituted chronotropic incompetence. Results: No differences were found in NYHA or pVO2 between patients with and without β-blockers and, similarly, between high and low β-blocker dose groups. Twenty and sixty-nine percent of not β-blocked patients showed chronotropic incompetence according to %Max PHR and %HRR, respectively, whereas this prevalence rose to 61% and 84% in those on β-blocker therapy. Patients taking β-blockers without chronotropic incompetence, as inferable from both %Max PHR and %HRR, showed higher NYHA and pVO2 regardless of drug dose, whereas, in not β-blocked patients, only %HRR revealed a difference in functional capacity. At multivariable analysis, HR increase during exercise (ΔHR) was the variable most strongly associated to pVO2 (β: 0.572; SE: 0.008; P < 0.0001) and NYHA class (β: −0.499; SE: 0.001; P < 0.0001). Conclusions: ΔHR is a powerful predictor of CHF severity regardless of the presence of β-blocker therapy and of β-blocker daily dose

Noninvasive measurement of cardiac output during exercise by inert gas rebreathing technique

Reduced exercise tolerance and dyspnea during exercise are hallmarks of heart failure syndrome. Exercise capacity and various parameters of cardiopulmonary response to exercise are of important prognostic value. All the available parameters only indirectly reflect left ventricular dysfunction and hemodynamic adaptation to an increased demand. Noninvasive assessment of cardiac output, especially during an incremental exercise stress test, would allow the direct measure of cardiac reserve and may become the gold standard for prognostic evaluation in the future

Exercise Training in Post-COVID-19 Patients: The Need for a Multifactorial Protocol for a Multifactorial Pathophysiology

The battle against COVID-19 has entered a new phase with Rehabilitation Centres being among the major players, because the medical outcome of COVID-19 patients does not end with the control of pulmonary inflammation marked by a negative virology test, as many patients continue to suffer from long-COVID-19 syndrome. Exercise training is known to be highly valuable in patients with cardiac or lung disease, and it exerts beneficial effects on the immune system and inflammation. We therefore reviewed past and recent papers about exercise training, considering the multifactorial features characterizing post-COVID-19 patients&rsquo; clinical conditions. Consequently, we conceived a proposal for a post-COVID-19 patient exercise protocol as a combination of multiple recommended exercise training regimens. Specifically, we built pre-evaluation and exercise training for post-COVID-19 patients taking advantage of the various programs of exercise already validated for diseases that may share pathophysiological and clinical characteristics with long-COVID-19

Hemodynamic effects of exercise training in heart failure

Exercise performance improvement after training in heart failure (HF) can be due to central or peripheral changes

Influence of exertional oscillatory ventilation on exercise performance in heart failure

BACKGROUND: Exertional oscillatory ventilation (EOV) in heart failure may potentiate the negative effects of low cardiac output and high ventilation on exercise performance. We hypothesized that the presence of EOV might, per se, influence exercise capacity as evaluated by maximal cardiopulmonary exercise test. METHODS AND RESULTS: We identified 78 severe chronic heart failure patient pairs with and without EOV. Patients were matched for sex, age and peak oxygen consumption (VO2). Patients with EOV showed, for the same peak VO2, a lower workload (WL) at peak (DeltaWatts=5.8+/-23.0, P=0.027), a less efficient ventilation (higher VE/VCO2 slope: 38.0+/-8.3 vs. 32.8+/-6.3, P<0.001), lower peak exercise tidal volume (1.49+/-0.36 L vs. 1.61+/-0.46 L, P=0.015) and higher peak respiratory rate (34+/-7/min vs. 31+/-6/min, P=0.002). In 33 patients, EOV disappeared during exercise, whereas in 45 patients EOV persisted. Fifty percent of EOV disappearing patients had an increase in the VO2/WL relationship after EOV regression, consistent with a more efficient oxygen delivery to muscles. No cardiopulmonary exercise test parameter was associated with the different behaviour of VO2/WL. CONCLUSION: The presence of EOV negatively influences exercise performance of chronic heart failure patients likely because of an increased cost of breathing. EOV disappearance during exercise is associated with a more efficient oxygen delivery in several cases

Prognostic Value of Dynamic Changes in Pulmonary Congestion During Exercise Stress Echocardiography in Heart Failure With Preserved Ejection Fraction

International audienceBackground: Patients with heart failure (HF) with preserved ejection fraction (HFpEF) typically develop dyspnoea and pulmonary congestion upon exercise. Lung ultrasound (LUS) is a simple diagnostic tool, providing semi-quantitative assessment of extravascular lung water through B-lines. It has been shown that HFpEF patients develop B-lines upon submaximal exercise stress echocardiography; however, whether exercise-induced pulmonary congestion carries prognostic implications is unknown. This study aimed at evaluating the prognostic value of B-line assessment during exercise in HFpEF patients.Methods: Sixty-one I–II NYHA class HFpEF patients underwent standard echocardiography, LUS (28-scanning point method), and B-type natriuretic peptide (BNP) assessment during supine exercise echocardiography (baseline and peak exercise). The primary endpoint was a composite of cardiovascular death or HF hospitalization at one-year. Results: B-lines, E/e’, and BNP significantly increased during exercise (P <0.001 for all). By multivariable analysis, both peak (HR 1.50, 95% CI 1.21–1.85, P <0.001), and change (HR 1.34, 95% CI 1.12–1.62, P =0.002) B-lines were retained as independent predictors of outcome (HRs per 1 B-line increment), along with BNP and E/e’ ratio. Importantly, adding peak B-line on top of a clinical model significantly improved prognostic accuracy (C-index increase=0.157, 0.056 to 0.258, P =0.002), and net reclassification (continuous NRI =0.51, 0.09 to 0.74, P =0.016), with similar results for B-line change.Conclusions: Detection of exercise-induced pulmonary congestion by LUS is an independent predictor of outcome in HFpEF patients; its use may help refining the routine risk-stratification of these patients on top of well-established clinical variables