Category Archives: Abstracts

The clinical value of cardiopulmonary exercise testing in the modern era.

Laveneziana P; Di Paolo M; Palange P;

European respiratory review : an official journal of the European Respiratory Society [Eur Respir Rev] 2021 Jan 06; Vol. 30 (159). Date of Electronic Publication: 2021 Jan 06 (Print Publication: 2021).

Cardiopulmonary exercise testing (CPET) has long been used as diagnostic tool for cardiac diseases. During recent years CPET has been proven to be additionally useful for 1) distinguishing between normal and abnormal responses to exercise; 2) determining peak oxygen uptake and level of disability; 3) identifying factors contributing to dyspnoea and exercise limitation; 4) differentiating between ventilatory (respiratory mechanics and pulmonary gas exchange), cardiovascular, metabolic and peripheral muscle causes of exercise intolerance; 5) identifying anomalies of ventilatory (respiratory mechanics and pulmonary gas exchange), cardiovascular and metabolic systems, as well as peripheral muscle and psychological disorders; 6) screening for coexistent ischaemic heart disease, peripheral vascular disease and arterial hypoxaemia; 7) assisting in planning individualised exercise training; 8) generating prognostic information; and 9) objectively evaluating the impact of therapeutic interventions. As such, CPET is an essential part of patients’ clinical assessment. This article belongs to the special series on the “Ventilatory efficiency and its clinical prognostic value in cardiorespiratory disorders”, addressed to clinicians, physiologists and researchers, and aims at encouraging them to get acquainted with CPET in order to help and orient the clinical decision concerning individual patients.

Prognostic value of aerobic capacity and exercise oxygen pulse in postaortic dissection patients.

Delsart P, Delahaye C, Devos P, Domanski O, Azzaoui R, Sobocinski J, Juthier F(, Vincentelli A, Rousse N, Mugnier A, Soquet J, Loobuyck V, Koussa M, Modine T, Jegou B, Bical A, Hysi I, Fabre O, Pontana F, Matran R, Mounier-Vehier C, Montaigne D.

Clin Cardiol. 2020 Dec 31. doi: 10.1002/clc.23537. Online ahead of print.

BACKGROUND: Although recommendations encourage daily moderate activities in post aortic dissection, very little data exists regarding cardiopulmonary exercise testing (CPET) to personalize those patient’s physical rehabilitation and assess their cardiovascular prognosis. DESIGN: We aimed at testing the prognostic insight of CPET regarding aortic and cardiovascular events by exploring a prospective cohort of patients followed-up after acute aortic dissection. METHODS: Patients referred to our department after an acute (type A or B) aortic dissection were prospectively included in a cohort between September 2012 and October 2017. CPET was performed once optimal blood pressure control was obtained. Clinical follow-up was done after CPET for new aortic event and major cardio-vascular events (MCE) not directly related to the aorta.
RESULTS: Among the 165 patients who underwent CPET, no adverse event was observed during exercise testing. Peak oxygen pulse was 1.46(1.22-1.84) mlO2/beat, that is, 97 (83-113) % of its predicted value, suggesting cardiac exercise limitation in a population under beta blockers (92% of the population). During a follow-up of 39(20-51) months from CPET, 42 aortic event recurrences and 22 MCE not related to aorta occurred. Low peak oxygen pulse (<85% of predicted value) was independently predictive of aortic event recurrence, while low peak oxygen uptake (<70% of predicted value) was an independent predictor of MCE occurrence.
CONCLUSION: CPET is safe in postaortic dissection patients should be used to not only to personalize exercise rehabilitation, but also to identify those patients with the highest risk for new aortic events and MCE not directly related to aorta.

Priming the cardiodynamic phase of pulmonary oxygen uptake through voluntary modulations of the respiratory pump at the onset of exercise

Experimental Physiology 28 December 2020

Abstract

We examined how different breathing patterns can modulate venous return and alveolar gas transfer during exercise transients in humans. Ten healthy men transitioned from rest to moderate cycling while breathing spontaneously (SP) or with voluntary increases in abdominal (AB) or intrathoracic (RC) pressure swings. We used double body plethysmography to determine blood displacements between the trunk and the extremities (Vbs). From continuous signals of airflow and O2 fraction, we calculated breath‐by‐breath oxygen uptake at the mouth and used optoelectronic plethysmography to correct for lung O2 stores changes and calculate alveolar O2 transfer. Oesophageal (Poes) and gastric (Pga) pressures were monitored using balloon‐tipped catheters. Cardiac stroke volume was measured using impedance cardiography. During the cardiodynamic phase (Φ1) of ‐on kinetics (20 s following exercise onset), AB and RC increased total alveolar oxygen transfer compared to SP (227±32, p = 0.019 vs 235±27, p = 0.001 vs 206±20 ml, mean±SD). Pga and Poes swings increased with AB (by 24.4±9.6 cm H2O, p<0.001) and RC (by 14.5±5.7 cm H2O, p<0.001), respectively. AB yielded a greater increase in intra‐breath Vbs swings compared with RC and SP (+0.30±0.14 vs +0.16±0.11, p<0.001 vs +0.10±0.05 ml, p = 0.006) and increased the sum of stroke volumes compared to SP (4.47±1.28 vs 3.89±0.96 L, p = 0.053), while RC produced significant central blood translocation from the extremities compared with SP (by 493±311 ml, p<0.001). Our findings indicate that combining exercise onset with AB or RC increases venous return, thus increasing mass oxygen transport above metabolic consumption during Φ1 and limiting the oxygen deficit incurred.

Reference Values for Chronotropic Index from 1280 Incremental Cycle Ergometry Tests

SIRICHANA, W; NEUFELD,  V.; WANG, XI; HU,  B.; DOLEZAL, A.; COOPER,  B;

Medicine & Science in Sports & Exercise: December 2020 – Volume 52 – Issue 12 – p 2515-2521

Purpose 
Clinical cardiopulmonary exercise testing can determine causes of exercise limitation. The slope of heart rate (fC) versus oxygen uptake (V˙O2), which we call the chronotropic index (CI), can help identify cardiovascular impairment. We aimed to develop a reference equation for CI based on a large number of subjects considered to have normal exercise responses.

Methods
From a database of 13,728 incremental cycle ergometry exercise tests, we identified 1280 normal tests based on the absence of a clinical diagnosis, normal body mass index, and normal aerobic performance plus absence of cardiovascular disease, medications, or ventilatory limitation. A linear mixed-model approach was used to analyze the relationship between CI and other variables.

Results 

Subjects were age 18–84 yr, and 693 (54.1%) were men. Mean ± SD CI in men was lower than in women, 41.2 ± 9.3 beats per liter versus 63.4 ± 15.7 L−1. Age (in years), sex (0, male; 1, female), height (in centimeters), and weight (in kilograms) were significant predictors for CI:CIi = 106.9 + 0.16 × agei + 14.3 × sexi − 0.31 × heighti − 0.24 × weighti. The SE of estimates ranged from 10.6 to 11.2 L−1 (median of 10.7 L−1).
Conclusions
We report a reference equation for CI derived from normal subjects. The CI can be used in conjunction with V˙O2max to interpret maximal cardiopulmonary exercise tests. We consider a high CI to be cardiovascular impairment and a low CI plus low V˙O2max to be chronotropic insufficiency.

Factors Contributing to Exercise Intolerance in Patients With Atrial Fibrillation.

Elliott AD; Verdicchio CV; Gallagher C; Linz D; Mahajan R; Mishima R; Kadhim K; Emami M; Middeldorp ME; Hendriks JM; Lau DH; Sanders P;

Heart, lung & circulation [Heart Lung Circ] 2020 Dec 16. Date of Electronic Publication: 2020 Dec 16.

Background: Reduced exercise capacity and exercise intolerance are commonly reported by individuals with atrial fibrillation (AF). Our objectives were to evaluate the contributing factors to reduced exercise capacity and describe the association between subjective measures of exercise intolerance versus objective measures of exercise capacity.
Methods: Two hundred and three (203) patients with non-permanent AF and preserved ejection fraction undergoing cardiopulmonary exercise testing (CPET) were recruited. Clinical characteristics, AF-symptom evaluation, and transthoracic echocardiography measures were collected. Peak oxygen consumption (VO2peak ) was calculated during CPET as an objective measure of exercise capacity. We assessed the impact of 16 pre-defined clinical features, comorbidities and cardiac functional parameters on VO2peak .
Results: Across this cohort (Age 66±11 years, 40.4% female and 32% in AF), the mean VO2peak was 20.3±6.3 ml/kg/min. 24.9% of patients had a VO2peak considered low (<16 ml/kg/min). In multivariable analysis, echocardiography-derived estimates of elevated left ventricular (LV) filling pressure (E/E’) and reduced chronotropic index were significantly associated with lower VO2peak . The presence of AF at the time of testing was not significantly associated with VO2peak but was associated with elevated minute ventilation to carbon dioxide production indicating impaired ventilatory efficiency. There was a poor association between VO2peak and subjectively reported exercise intolerance and exertional dyspnoea.
Conclusion: Reduced exercise capacity in AF patients is associated with elevated LV filling pressure and reduced chronotropic response rather than rhythm status. Subjectively reported exercise intolerance is not a sensitive assessment of reduced exercise capacity. These findings have important implications for understanding reduced exercise capacity amongst AF patients and the approach to management in this cohort.

Heart rate recovery in patients with hypertrophic cardiomyopathy.

Patel V; Critoph CH; Finlay MC; Mist B; Lambiase PD; Elliott PM.

American Journal of Cardiology. 113(6):1011-7, 2014 Mar 15.

Abstract
Recovery in heart rate (HR) after exercise is a measure of autonomic
function and a prognostic indicator in cardiovascular disease. The aim of
this study was to characterize heart rate recovery (HRR) and to determine
its relation to cardiac function and morphology in patients with
hypertrophic cardiomyopathy (HC).
We studied 18 healthy volunteers and 41
individuals with HC. All patients underwent clinical assessment and
transthoracic echocardiography. Continuous beat-by-beat assessment of HR
was obtained during and after cardiopulmonary exercise testing using
finger plethysmography. HRR and power spectral densities were calculated
on 3 minutes of continuous RR recordings.
Absolute HRR was lower in
patients than that in controls at 1, 2, and 3 minutes (25.7 +/- 8.4 vs
35.3 +/- 11.0 beats/min, p <0.001; 36.8 +/- 9.4 vs 53.6 +/- 13.2
beats/min, p <0.001; 41.2 +/- 12.2 vs 62.1 +/- 14.5 beats/min, p <0.001,
respectively). HRR remained lower in patients at 2 and 3 minutes after
normalization to peak HR. After normalization to the difference in HR
between peak exercise and rest, HRR was significantly impaired in
individuals with obstructive HC at 3 minutes compared with controls. HR at
3 minutes correlated with peak left ventricular outflow tract gradient (B
0.154 beats/min/mm Hg, confidence interval 0.010 to 0.299, p = 0.037) and
remained a significant predictor of HRR after multivariable analysis.
Spectral analysis showed a trend toward an increased low-frequency to
high-frequency ratio in patients (p = 0.08) suggesting sympathetic
predominance.
In conclusion, HRR is impaired in HC and correlates with the
severity of left ventricular outflow tract gradient. Prospective studies
of the prognostic implications of impaired HRR in HC are warranted.

High-intensity interval training in cardiac resynchronization therapy: a randomized control trial.

Santa-Clara H; Abreu A; Melo X; Santos V; Cunha P; Oliveira M; Pinto R;
Carmo MM; Fernhall B.

European Journal of Applied Physiology. 119(8):1757-1767, 2019 Aug.
VI 1

AIMS: To determine the effects of high-intensity interval training (HIIT)
following cardiac resynchronization therapy (CRT) implantation in patients
with chronic heart failure (CHF), on noninvasive estimates of systolic
ventricular function, exercise performance, severity of symptoms and
quality of life.

METHODS: Cardiopulmonary exercise testing, resting transthoracic
echocardiogram and health-related quality of life assessment were obtained
before and at 6 months after CRT implantation in 37 patients with
moderate-to-severe CHF. Patients were randomized after CRT to either a
24-week HIIT group (90-95% peak heart rate, 2 days per week) or to a usual
care group (CON). Mixed design 2 x 2 repeated measures ANOVA were used to
test for differences within and in-between groups.

RESULTS: Improvements in health-related quality of life (HIIT = 98.54%,
CON = 123.47%), NYHA class (HIIT = 43.44%, CON = 38.30%) HR recovery at
minute 1 (HIIT = 32.32%, CON = 42.94%), pulse pressure at peak effort
(HIIT = 14.06%, CON = 9.52%, LVEF (HIIT = 42.17%, CON = 51.10%) and LV
Mass (HIIT = 13.26%, CON = 11.88%) were similar in both groups (p > 0.05).
Significant increases in CPET duration in the HIIT group (25.94%), and
increases in peak VO2 (HIIT = 8.64%, CON = 4.85%) and percent-predicted
VO2 (HIIT = 10.57%, CON = 4.26%) in both groups, were observed in the
intention-to-treat analysis.

CONCLUSION: Six months of HIIT in patients in CRT did not further
improved indices of functional capacity and health-related quality of
life, and LV structure and function, compared to CRT alone. However, HIIT
led to further improvements in exercise performance. It remains unclear
whether HIIT benefits patients in CRT to a similar degree as more
conventional forms of exercise training previously shown to maximize
benefits in CRT.

L-Arginine Improves Endurance to High-Intensity Interval Exercises in Overweight Men.

Daraei A; Ahmadizad S; Rahmani H; Hackney AC; Johnson KE; Laher I; Saeidi A; Zouhal H;

International journal of sport nutrition and exercise metabolism [Int J Sport Nutr Exerc Metab] 2020 Dec 01, pp. 1-9. Date of Electronic Publication: 2020 Dec 01.

The effects of acute consumption of L-Arginine (L-Arg) in healthy young individuals are not clearly defined, and no studies on the effects of L-Arg in individuals with abnormal body mass index undertaking strenuous exercise exist. Thus, we examined whether supplementation with L-Arg diminishes cardiopulmonary exercise testing responses, such as ventilation (VE), VE/VCO2, oxygen uptake (VO2), and heart rate, in response to an acute session of high-intensity interval exercise (HIIE) in overweight men. A double-blind, randomized crossover design was used to study 30 overweight men (age, 26.5 ± 2.2 years; body weight, 88.2 ± 5.3 kilogram; body mass index, 28.0 ± 1.4 kg/m2). Participants first completed a ramped-treadmill exercise protocol to determine VO2max velocity (vVO2max), after which they participated in two sessions of HIIE. Participants were randomly assigned to receive either 6 g of L-Arg or placebo supplements. The HIIE treadmill running protocol consisted of 12 trials, including exercise at 100% of vVO2max for 1 min interspersed with recovery intervals of 40% of vVO2max for 2 min. Measurements of VO2 (ml·kg-1·min-1), VE (L/min), heart rate (beat per min), and VE/VCO2 were obtained. Supplementation with L-Arg significantly decreased all cardiorespiratory responses during HIIE (placebo+HIIE vs. L-Arg+HIIE for each measurement: VE [80.9 ± 4.3 L/min vs. 74.6 ± 3.5 L/min, p < .05, ES = 1.61], VE/VCO2 [26.4 ± 1.3 vs. 24.4 ± 1.0, p < .05, ES = 1.8], VO2 [26.4 ± 0.8 ml·kg-1·min-1 vs. 24.4 ± 0.9 ml·kg-1·min-1, p < .05, ES = 2.2], and heart rate [159.7 ± 6.3 beats/min vs. 155.0 ± 3.7 beats/min, p < .05, d = 0.89]).
The authors conclude consuming L-Arg before HIIE can alleviate the excessive physiological strain resulting from HIIE and help to increase exercise tolerance in participants with a higher body mass index who may need to exercise on a regular basis for extended periods to improve their health.

Hemodynamic and Clinical Implications of Impaired Pulmonary Vascular Reserve in the Fontan Circulation.

Egbe AC; Miranda WR; Anderson JH; Borlaug BA;

Journal of the American College of Cardiology [J Am Coll Cardiol] 2020 Dec 08; Vol. 76 (23), pp. 2755-2763.

Background: Pulmonary vascular disease, pulmonary endothelial dysfunction, liver fibrosis, renal disease, and exercise intolerance are common in adults with Fontan physiology. Although the pathophysiologic mechanisms linking these phenomena have been studied, certain aspects are not well understood.
Objectives: This study hypothesized that impaired pulmonary vascular reserve (VR) plays a central role linking these abnormalities, and that patients with abnormal pulmonary VR with exercise, compared with patients with normal VR, would display poorer pulmonary endothelial function, greater liver stiffness, more renal dysfunction, and poorer exercise capacity.
Methods: Symptomatic adults with the Fontan palliation (n = 29) underwent invasive cardiopulmonary exercise testing, echocardiography, and assessment of microvascular function. Abnormal pulmonary VR was defined by the slope of increase in pulmonary pressure relative to cardiac output with exercise >3 mm Hg/l/min. Pulmonary endothelial function was assessed using reactive hyperemia index. End-organ function was assessed using magnetic resonance elastography-derived liver stiffness, glomerular filtration rate, N-terminal pro-B-type natriuretic peptide, and peak oxygen consumption (Vo 2 ).
Results: Compared with individuals with normal VR (n = 8), those with abnormal VR (n = 21) displayed higher central and pulmonary venous pressures, and more severely impaired cardiac output and stroke volume responses to exertion, but similar pulmonary vascular resistance at rest. Patients with abnormal VR displayed more severely impaired reactive hyperemia index, increased liver stiffness, lower glomerular filtration rate, higher N-terminal pro-B-type natriuretic peptide, and lower peak Vo 2 . As compared to pulmonary vascular resistance at rest, slope of increase in pulmonary pressure relative to cardiac output displayed stronger correlations with reactive hyperemia index (r = -0.63 vs. r = -0.31; Meng test p = 0.009), magnetic resonance elastography-derived liver stiffness (r = 0.47 vs. r = 0.29; Meng test p = 0.07), glomerular filtration rate (r = -0.52 vs. r = -0.24; Meng test p = 0.03), N-terminal pro-B-type natriuretic peptide (r = 0.56 vs. r = 0.17; Meng test p = 0.02), and peak Vo 2 (r = -0.63 vs. r = -0.26; Meng test p = 0.02).
Conclusions: Pulmonary vascular limitations in Fontan physiology are related to pulmonary endothelial and end-organ dysfunction, suggesting a mechanistic link between these commonly observed findings, and these abnormalities are more apparent during exercise testing, with little relationship at rest.