Limitations to high intensity exercise prescription in chronic heart failure patients

BACKGROUND

Interval training is recommended for chronic heart failure patients (CHF), but specific guidelines on setting appropriate workloads have not been fully established. The aim of this study was to compare a traditional method of interval training prescription with a protocol specifically designed for CHF.

METHODS

Ten CHF and 7 healthy controls performed 2 maximal incremental cycle tests to determine interval training workload; a standard test (10Wmin(-)(1)) and a steep test (25W.10(-)(s)). Peak work rate and oxygen uptake (VO(2 peak)) were determined. Training workloads were defined as 100% standard test and 50% steep test peak work rate.

RESULTS

Training workload determined from the standard test was higher than from the steep test in healthy controls (151 ± 17W vs 118 ± 13W; P<0.01), whereas in CHF there was no significant difference between methods (88 ± 10W vs 96 ± 9W; P>0.05). Steep test VO(2peak) reached 91 ± 5% of standard test VO(2 peak) in controls, and 99 ± 4% in CHF, with no significant differences between tests in either group.

CONCLUSION

Prescribing interval training from a standard test results in higher workloads than from a steep test in healthy individuals, but in CHF both methods prescribe similar workloads. However it should not be assumed that the two tests can be used interchangeably for CHF. This small-sized study raises issues about interval training prescription that may be hypothesis-generating for future larger-scale studies.

Age-related prolongation of phase I of VO2 on-kinetics in healthy humans

Data are lacking regarding age-related modifications of phase I (PhI) of pulmonary Vo(2) on-kinetics during moderate-intensity exercise. We studied three groups (aged 20-30, 40-50, and 60-70 years) of 10 normal subjects, who underwent one incremental and four below-gas exchange threshold constant-power cardiopulmonary exercise tests. Data from constant-power tests were time-aligned and averaged, and the PhI-phase II transition (PhI-IItr) determined when a sharp decrease from baseline of respiratory exchange ratio occurred. The Vo(2) phase II time constant (tau) was obtained by an exponential fitting starting 1) from PhI-IItr ("experimental" fitting strategy) and 2) after 20 s from exercise onset ("fixed-duration" fitting strategy). Assuming estimated arterial-venous O(2) concentration difference not to change with respect to resting value, cardiac output (CO) values at rest and PhI-IItr were obtained according to Fick's principle. Average pulmonary flow acceleration (AFA) during PhI was calculated as the ratio between CO increase during PhI and PhI duration. PhI duration was related to age (r = 0.74, P < 0.0001), increasing from 21 +/- 3 s to 27 +/- 3 s to 32 +/- 4 s in the 20-30, 40-50, and 60-70 age groups, respectively, and to AFA (r = -0.60, P < 0.001), but not to CO increase during PhI. With respect to the experimental fitting strategy, the fixed-duration strategy overestimated Vo(2) phase II tau the more the higher the subject's age, with a lower goodness of fit in the 60-70 group (SE 0.035 vs. 0.056, P < 0.01). In conclusion, PhI duration is related to age in healthy male humans and is linked to CO acceleration-rather than to increase-during PhI. A significant overestimation of phase II tau thus may occur in healthy elderly subjects and patients with a pathologically induced longer PhI duration when fitting data where the PhI-PhIItr was not experimentally determined but assumed to be a set value (i.e., 20 s).

Impaired heart rate recovery index in patients with sarcoidosis

BACKGROUND

Sarcoidosis, an inflammatory granulomatous disease, is associated with various cardiac disorders, including threatening ventricular arrhythmias and sudden cardiac death. Heart rate recovery (HRR) after exercise is a function of vagal reactivation, and its impairment is an independent prognostic indicator for cardiovascular and all-cause mortality. The aim of our study was to evaluate HRR in patients with sarcoidosis.

METHODS

The study population included 56 patients with sarcoidosis (23 men, mean age = 47.3 ± 13.0 years, and mean disease duration = 38.4 ± 9.7 months) and 54 healthy control subjects (20 men, mean age = 46.5 ± 12.9 years). Basal ECG, echocardiography, and treadmill exercise testing were performed on all patients and control participants. The HRR index was defined as the reduction in the heart rate at peak exercise to the first-minute rate (HRR(1)), second-minute (HRR(2)), third-minute (HRR(3)), and fifth-minute (HRR(5)) after the cessation of exercise stress testing.

RESULTS

There are significant differences in HRR(1) and HRR(2) indices between patients with sarcoidosis and the control group (25 ± 6 vs 34 ± 11; P < .001 and 45 ± 10 vs 53 ± 12; P < .001, respectively). Similarly, HRR(3) and HRR(5) indices of the recovery period were lower in patients with sarcoidosis when compared with indices in the control group (53 ± 12 vs 61 ± 13; P < .001 and 60 ± 13 vs 68 ± 13; P < .001, respectively). Exercise capacity was notably lower (9.2 ± 2.1 vs 11.6 ± 2.8 METs; P = .001, respectively) and systolic pulmonary arterial pressure at rest was significantly higher in patients with sarcoidosis compared with the control group (29.7 ± 5.5 mm Hg vs 25.6 ± 5.7 mm Hg, P = .001, respectively). Furthermore, HRR indices were found to be different among radiographic stage groups.

CONCLUSIONS

The HRR index was impaired in patients with sarcoidosis as compared with control subjects. When the prognostic significance of the HRR index is considered, these results may partially explain the increased occurrence of arrhythmias and sudden cardiac death in patients with sarcoidosis. Our findings suggest that the HRR index may be clinically helpful in identifying high-risk patients with sarcoidosis.

Cardiopulmonary Exercise Testing in Patients with Chronic Heart Failure: Prognostic Comparison from Peak VO2 and VE/VCO2 Slope

BACKGROUND

Cardiopulmonary exercise testing with ventilatory expired gas analysis (CPET) has proven to be a valuable tool for assessing patients with chronic heart failure (CHF). The maximal oxygen uptake (peak V02) is used in risk stratification of patients with CHF. The minute ventilation-carbon dioxide production relationship (VE/VCO2 slope) has recently demonstrated prognostic significance in patients with CHF.

METHODS

Between January 2006 and December 2007 we performed CPET in 184 pts (146 M, 38 F, mean age 59.8 +/- 12.9 years), with stable CHF (96 coronary artery disease, 88 dilated cardiomyopathy), in NYHA functional class II (n.107) - III (n.77), with left ventricular ejection fraction (LVEF)

RESULTS

Peak VO2 and VE/VCO2 slope were demonstrated with univariate Cox regression analysis both to be significant predictor of cardiac-related mortality and hospitalization (p < 0.0001, respectively). Non survivors had a lower peak VO2 (10.49 +/- 1.70 ml/kg/min vs. 14.41 +/- 3.02 ml/kg/min, p < 0.0001), and steeper Ve/VCO2 slope (41.80 +/- 8.07 vs. 29.84 +/- 6.47, p < 0.0001) than survivors. Multivariate survival analysis revealed that VE/VCO2 slope added additional value to VO2 peak as an independent prognostic factor (chi2: 56.48, relative risk: 1.08, 95% CI: 1.03 - 1.13, p = 0.001). The results from Kaplan-Meier analysis revealed a 1-year cardiac-related mortality of 75% in patients with VE/VCO2 slope >/= 35.6 and 25% in those with VE/VCO2 slope < 35.6 (log rank chi2: 67.03, p < 0.0001) and 66% in patients with peak VO2 12.2 ml/kg/min (log rank chi2: 50.98, p < 0.0001). One-year cardiac-related hospitalization was 77% in patients with VE/VCO2 slope >/= 32.5 and 23% in those with VE/VCO2 slope < 32.5 (log rank chi2: 133.80, p < 0.0001) and 63% in patients with peak VO2 12.3 ml/kg/min (log rank chi2: 72.86, p < 0.0001). The VE/VCO2 slope was demonstrated with receiver operating characteristic curve analysis to be equivalent to peak VO2 in predicting cardiac-related mortality (0.89 vs. 0.89). Although area under the receiver operating characteristic curve for the VE/VCO2 slope was greater than peak VO2 in predicting cardiac-related hospitalization (0.88 vs 0.82), the difference was no statistically significant (p = 0.13).

CONCLUSION

These results add to the present body of knowledge supporting the use of CPET in CHF patients. The VE/VCO2 slope, as an index of ventilatory response to exercise, is an excellent prognostic parameter and improves the risk stratification of CHF patients. It is easier to obtain than parameters of maximal exercise capacity and is of equivalent prognostic importance than peak VO2.

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Key Words

• Congestive heart failure
• exercise capacity
• gas exchange
• prognosis.
• ventilation

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MESH Headings Collapse

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Affiliation(s)

Filippo Maria Sarullo Division of Cardiology, Buccheri La Ferla Fatebenefratelli Hospital Palermo, Italy
Giovanni Fazio Department of Cardiology, University of Palermo, Italy
Ignazio Brusca Clinical Phatology Service, Buccheri La Ferla Fatebenefratelli Hospital Palermo, Italy
Sergio Fasullo Division of Cardiology “P. Borsellino”, G.F. Ingrassia Hospital - Palermo – Italy
Salvatore Paterna Department of Internal Medicine, University of Palermo - Italy
Pamela Licata Department of Cardiology, University of Palermo, Italy
Giuseppina Novo Department of Cardiology, University of Palermo, Italy
Salvatore Novo Department of Cardiology, University of Palermo, Italy
Pietro Di Pasquale Division of Cardiology “P. Borsellino”, G.F. Ingrassia Hospital - Palermo – Italy

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Systolic blood pressure response to exercise as a predictor of mortality in patients with chronic heart failure

It is well known that peak oxygen consumption and heart rate (HR) recovery after exercise obtained from the cardiopulmonary exercise test are prognostic parameters in patients with chronic heart failure (CHF). However, it is unclear whether exercise-induced parameters obtained from the routine exercise stress test predict mortality in patients with CHF. We studied 136 patients (93 males/43 females) with CHF. All patients underwent symptom-limited exercise stress testing. Exercise parameters included exercise duration, exercise-induced HR and systolic blood pressure (SBP), and metabolic equivalents (METs). During the follow-up period (mean 6.2 years), 34 patients died. Survival rates at the 3rd and 5th years were 90% and 83%, respectively. Body mass index was significantly smaller in the nonsurvival group than in the survival group (P < 0.01). The incidence of patients with New York Heart Association III class was higher in the nonsurvival group than in the survival group (P < 0.05). In univariate analysis, predictors of mortality included peak HR and SBP, increases in HR and SBP during exercise, HR and SBP at the 1st minute after exercise, HR at the 3rd minute after exercise, and METs. The use of beta-adrenergic blocking agents was not associated with prognosis. In Cox hazard model analysis, the increase in SBP (P < 0.002), HR at the 3rd minute after exercise (P < 0.05), and METs (P < 0.05) were independent predictors of mortality. SBP response to exercise, HR recovery after exercise, and METs obtained from the routine exercise test predicted mortality in patients with CHF irrespective of the use of beta-adrenergic blocking agents.

Near-infrared spectroscopy during stagnant ischemia estimates central venous oxygen saturation and mixed venous oxygen saturation discrepancy in patients with severe left heart failure and additional sepsis/septic shock

Introduction

Discrepancies of 5-24% between superior vena cava oxygen saturation (ScvO₂) and mixed venous oxygen saturation (SvO₂) have been reported in patients with severe heart failure. Thenar muscle tissue oxygenation (StO₂) measured with near-infrared spectroscopy (NIRS) during arterial occlusion testing decreases slower in sepsis/septic shock patients (lower StO₂ deoxygenation rate). The StO₂ deoxygenation rate is influenced by dobutamine. The aim of this study was to determine the relationship between the StO₂ deoxygenation rate and the ScvO₂-SvO₂ discrepancy in patients with severe left heart failure and additional sepsis/septic shock treated with or without dobutamine.

Methods

Fifty-two patients with severe left heart failure due to primary heart disease with additional severe sepsis/septic shock were included. SvO₂ and ScvO₂ were compared to the thenar muscle StO₂ before and during arterial occlusion.

Results

SvO₂ correlated significantly with ScvO₂ (Pearson correlation 0.659, P = 0.001), however, Bland Altman analysis showed a clinically important difference between both variables (ScvO₂-SvO₂ mean 72 ± 8%, ScvO₂-SvO₂ difference 9.4 ± 7.5%). The ScvO₂-SvO₂ difference correlated with plasma lactate (Pearson correlation 0.400, P = 0.003) and the StO₂ deoxygenation rate (Pearson correlation 0.651, P = 0.001). In the group of patients treated with dobutamine, the ScvO₂-SvO₂ difference correlated with plasma lactate (Pearson correlation 0.389, P = 0.011) and the StO₂ deoxygenation rate (Pearson correlation 0.777, P = 0.0001).

Conclusions

In patients with severe heart failure with additional severe sepsis/septic shock the ScvO₂-SvO₂ discrepancy presents a clinical problem. In these patients the skeletal muscle StO₂ deoxygenation rate is inversely proportional to the difference between ScvO₂ and SvO₂; dobutamine does not influence this relationship. When using ScvO₂ as a treatment goal, the NIRS measurement may prove to be a useful non-invasive diagnostic test to uncover patients with a normal ScvO₂ but potentially an abnormally low SvO₂.

Trial Registration

NCT00384644 ClinicalTrials.Gov.

The hypertensive heart. An integrated understanding informed by imaging

Clinical sequelae of hypertension include heart failure, arrhythmias, and ischemic events, especially myocardial infarction and stroke. Recognizing the hypertensive heart has diagnostic as well as prognostic implications. Current imaging techniques offer noninvasive approaches to detecting myocardial fibrosis, ischemia, hypertrophy, and disordered metabolism that form the substrate for hypertensive heart disease. In addition, recognition of aortopathy and atrial myopathy as contributors to myocardial disease warrant incorporation of aortic and atrial functional measurements into a comprehensive understanding of the hypertensive heart.

Relation of heart rate recovery to psychological distress and quality of life in patients with chronic heart failure

BACKGROUND

Psychological distress, poor disease-specific quality of life (QoL), and reduction in vagally mediated early heart rate recovery (HRR) after exercise, all previously predicted morbidity and mortality in patients with chronic heart failure (CHF). We hypothesized lower HRR with greater psychological distress and poorer QoL in CHF.

DESIGN

All assessments were made at the beginning of a comprehensive cardiac outpatient rehabilitation intervention program.

METHODS

Fifty-six CHF patients (mean 58+/-12 years, 84% men) completed the Hospital Anxiety and Depression Scale and the Minnesota Living With Heart Failure Questionnaire. HRR was determined as the difference between HR at the end of exercise and 1 min after exercise termination (HRR-1).

RESULTS

Elevated levels of anxiety symptoms (P=0.005) as well as decreased levels of the Minnesota Living With Heart Failure Questionnaire total (P = 0.025), physical (P=0.026), and emotional (P=0.017) QoL were independently associated with blunted HRR-1. Anxiety, total, physical, and emotional QoL explained 11.4, 8, 7.8, and 9.0%, respectively, of the variance after controlling for covariates. Depressed mood was not associated with HRR-1 (P=0.20).

CONCLUSION

Increased psychological distress with regard to elevated anxiety symptoms and impaired QoL were independent correlates of reduced HRR-1 in patients with CHF. Reduced vagal tone might explain part of the adverse clinical outcome previously observed in CHF patients in relation to psychological distress and poor disease-specific QoL.

Heart rate recovery and oxygen kinetics after exercise in obstructive sleep apnea syndrome

BACKGROUND

Patients who suffer from obstructive sleep apnea (OSA) have a decreased exercise capacity and abnormal autonomic nervous function. However, the kinetics of early oxygen (O2) and heart rate recovery (HRR) have not been described.

MATERIALS AND METHODS

We evaluated 21 men with moderate to severe OSA (mean age: 48 +/- 11 yrs, mean apnea-hypopnea index [AHI]: 55 +/- 13) and without known heart disease and 10 healthy men matched for age and body mass index (BMI; controls). Men with OSA underwent overnight polysomnography, and both groups underwent symptom-limited incremental cardiopulmonary exercise testing (CPET). We recorded the CPET parameters including peak O2 uptake (VO2p), kinetics of early O2 recovery by the first degree slope of VO2 during the first minute (VO2/t slope), the time required for a 50% decline of VO2p during recovery (T(1/2)), and early heart rate recovery (HRR = HR at maximal exercise - HR at 1 min of recovery), as well as the chronotropic reserve to exercise ([CR] = [peak HR - resting HR/220 - age - resting HR] x 100). Patients with OSA had a lower VO2p (28.7 +/- 4.0 vs 34.7 +/- 6.2 mL/kg/min), VO2/t slope (1.04 +/- 0.3 vs 1.4 +/- 0.17 mL/kg/min2), and T(1/2) (74 +/- 10 vs 56 +/- 6 sec) compared to controls (all P < 0.001). In addition, both HRR and CR were lower in the OSA group (22.0 +/- 7.0 vs 31.0 +/- 6.0 bpm, P:0.003, and 79.0% +/- 15% vs 99.0% +/- 13.0%, P:0.01, respectively).

CONCLUSIONS

Patients with OSA demonstrate reduced exercise capacity, delayed oxygen kinetics, and reduced HRR. These data point to abnormal oxygen delivery and/or oxidative function of the peripheral muscles and impaired autonomic nervous activity in OSA patients.

Impairment of autonomic nervous system activity in patients with pulmonary arterial hypertension: a case control study

BACKGROUND

Chronotropic response to exercise (CR) and heart rate recovery (HRR) immediately after exercise are indirect indices of sympathetic and parasympathetic activity, respectively. The aim of this study was to evaluate CR and HRR in patients with pulmonary arterial hypertension (PAH) in relation to disease severity.

METHODS AND RESULTS

Ten PAH patients (6 females/4 males, mean age: 48+/-12 years) and 10 control subjects matched for age, gender, and body mass index (6 females/4 males, mean age: 46+/-6 years) performed a ramp incremental symptom-limited cardiopulmonary exercise test on a cycle ergometer. Main measurements included heart rate at rest (HR), CR=[(peak HR-resting HR/220-age-resting HR)x100, %], HRR(1)=HR difference from peak exercise to 1minute after, ventilatory efficiency during exercise (VE/VCO(2) slope), peak oxygen uptake (VO(2)p), and the first-degree slope of VO(2) for the first minute of the recovery period (VO(2)/t-slope). PAH patients had a significantly decreased CR (58+/-31 vs 92+/-13, %, P < .001) and HRR(1) (10+/-5 vs 29+/-6, beats/min, P < .001) as well as VO(2)p (11.9+/-3.5 vs 26.9+/-6.6, mL.kg.min) and VO(2)/t-slope (0.2+/-0.1 vs. 0.9+/-0.2, mL.kg.min(2)) compared with controls. CR and HRR(1) correlated well with VO(2)p (r=0.7; P < .001 and r=0.85; P < .001, respectively) and VO(2)/t-slope (r=0.66; P < .001 and r=0.85; P < .001, respectively) and had a significant inverse correlation with VE/VCO(2) slope (r=-0.47; P < .01 and r=-0.77; P < .001, respectively).

CONCLUSIONS

PAH patients present a significant impairment of CR and HRR(1) in relation to disease severity, indicating profound autonomic nervous system abnormalities.

Assessment of tissue oxygen saturation during a vascular occlusion test using near-infrared spectroscopy: the role of probe spacing and measurement site studied in healthy volunteers

Introduction

To assess potential metabolic and microcirculatory alterations in critically ill patients, near-infrared spectroscopy (NIRS) has been used, in combination with a vascular occlusion test (VOT), for the non-invasive measurement of tissue oxygen saturation (StO₂), oxygen consumption, and microvascular reperfusion and reactivity. The methodologies for assessing StO₂ during a VOT, however, are very inconsistent in the literature and, consequently, results vary from study to study, making data comparison difficult and potentially inadequate. Two major aspects concerning the inconsistent methodology are measurement site and probe spacing. To address these issues, we investigated the effects of probe spacing and measurement site using 15 mm and 25 mm probe spacings on the thenar and the forearm in healthy volunteers and quantified baseline, ischemic, reperfusion, and hyperemic VOT-derived StO₂ variables.

Methods

StO₂ was non-invasively measured in the forearm and thenar in eight healthy volunteers during 3-minute VOTs using two InSpectra tissue spectrometers equipped with a 15 mm probe or a 25 mm probe. VOT-derived StO₂ traces were analyzed for base-line, ischemic, reperfusion, and hyperemic parameters. Data were categorized into four groups: 15 mm probe on the forearm (F_{15 mm}), 25 mm probe on the forearm (F_{25 mm}), 15 mm probe on the thenar (T_{15 mm}), and 25 mm probe on the thenar (T_{25 mm}).

Results

Although not apparent at baseline, probe spacing and measurement site significantly influenced VOT-derived StO₂ variables. For F_{15 mm}, F_{25 mm}, T_{15 mm}, and T_{25 mm}, StO₂ ownslope was -6.4 ± 1.7%/minute, -10.0 ± 3.2%/minute, -12.5 ± 3.0%/minute, and -36.7 ± 4.6%/minute, respectively. StO₂ upslope was 105 ± 34%/minute, 158 ± 55%/minute, 226 ± 41%/minute, and 713 ± 101%/minute, and the area under the hyperemic curve was 7.4 ± 3.8%·minute, 10.1 ± 4.9%·minute, 12.6 ± 4.4%·minute, and 21.2 ± 2.7%·minute in these groups, respectively. Furthermore, the StO₂ parameters of the hyperemic phase of the VOT, such as the area under the curve, significantly correlated to the minimum StO₂ during ischemia.

Conclusions

NIRS measurements in combination with a VOT are measurement site-dependent and probe-dependent. Whether this dependence is anatomy-, physiology-, or perhaps technology-related remains to be elucidated. Our study also indicated that reactive hyperemia depends on the extent of ischemic insult.

Physical exercise improves the peripheral microcirculation of patients with chronic heart failure

PURPOSE

Patients with chronic heart failure (CHF) present with microcirculation alterations, partially attributed to endothelial dysfunction. Exercise training has been shown to induce beneficial effects in CHF patients. The aim of our study was to assess the effect of physical exercise on the microcirculation of CHF patients by near-infrared spectroscopy (NIRS).

METHODS

Sixteen consecutive stable CHF patients (men, n = 10; mean age = 50 +/- 12 years) participated in a 3-month rehabilitation program (3 sessions per week). All patients performed symptom-limited, ramp-incremental cardiopulmonary exercise testing on a cycle ergometer before and after the completion of the program. Measurements included peak oxygen uptake (VO2peak), VO2 at anaerobic threshold (AT), and first-degree slope of VO2 during the first minute of recovery (VO2/t slope). Tissue oxygen saturation was continuously measured by NIRS at the thenar muscle during a 3-minute vascular occlusion with a pneumatic cuff (occlusion technique) before and after the rehabilitation program.

RESULTS

The oxygen reperfusion rate (%/min) following the release of vascular occlusion increased significantly after the rehabilitation program (450 +/- 105 to 532 +/- 151, P = .004) as did vascular reactivity (from 27 +/- 13%/min to 39 +/- 21%/min, P = .006). In addition, there was a significant increase in VO2peak and AT (from 14.3 +/- 4.7 mL . kg . min to 16.7 +/- 6.3 mL . kg . min and from 9.5 +/- 3.6 mL . kg . min to 11.3 +/- 4 mL . kg . min, P = .007 and P = .012, respectively) as well as in VO2/t slope (from 0.35 +/- 0.17 to 0.51 +/- 0.07 mL . kg . min, P = .005).

CONCLUSIONS

Peripheral microcirculation of CHF patients measured by NIRS improved after the rehabilitation program. NIRS is a noninvasive technique that could be used to evaluate the effect of rehabilitation on the peripheral microcirculation of CHF patients.

Prognostic evaluation of QT-dispersion in elderly hypertensive and normotensive patients

BACKGROUND

QT-corrected interval dispersion (QTcD) is an indirect index of increased heterogeneity of ventricular repolarization. However, the prognostic value of (QTcD) in elderly hypertensive and normotensive patients has not been thoroughly investigated yet.

METHODS

The study population consisted of 60 consecutive patients (34 males/26 females; mean age: 63+/-11 years) with mild to moderate essential arterial hypertension and 48 consecutive age-matched healthy subjects (24 males/24 females; 65+/-16 years). QTcD was measured by a 12-lead electrocardiogram (ECG) as the difference between maximum and minimum QT-interval, corrected for heart rate. Ventricular arrhythmias were recorded by a 24-hour Holter ECG and classified by a modified Lown's score (range: 0-6). Left ventricular mass was measured echocardiographically and indexed by body surface area [left ventricular mass index (LVMI)]. Nine patients were lost during the follow-up period. Patients were followed up for 54+/-9 months, and the primary end-point was the major cardiovascular events (including cardiac mortality).

RESULTS

Major cardiovascular events occurred in 22 patients (22%). Patients with QTcD>or=45 ms (n=35) had a higher rate of major cardiovascular events (43% vs 11%; log rank: 14.8; P<0.001), a higher LVMI (146+/-29 vs 104+/-21 g/m2; P<0.001), greater values of systolic and diastolic blood pressure (154+/-16 vs 144+/-18 mmHg; P<0.01 and 92+/-10 vs 88+/-8 mmHg; P<0.05, respectively), a higher number of premature ventricular beats (354+/-870 vs 113+/-301; P<0.05), and a greater Lown's score (3.7+/-1.9 vs 1.4+/-1.8; P<0.05) than patients with QTcD<45 ms. QTcD (>or=or<45 ms) was an independent predictor of major cardiovascular events (odds ratio: 4.9; 95% confidence interval: 2.0-12.1; P=0.001) after adjustment for LVMI, Lown's score (>or=or<3), age (>or=or<65 years), and QTc max (>or=or<437 ms).

CONCLUSIONS

QTcD is an independent predictor of major cardiovascular events in elderly hypertensive and normotensive patients and might be used in their risk stratification.

Abnormal blood pressure response to exercise occurs more frequently in hypertrophic cardiomyopathy patients with the R92W troponin T mutation than in those with myosin mutations

Abnormal blood pressure response to exercise is reported to occur in up to a third of hypertrophic cardiomyopathy (HCM) cases and is associated with an increased risk of death, particularly in the young, but it is not known whether the HCM-causing mutation influences blood pressure response to exercise. The purpose of this article is to ascertain whether the blood pressure response to exercise differs among carriers of the R92W mutation in the cardiac troponin T gene (TNNT2), which has been associated with an increased risk of sudden cardiac death in young males; carriers of mutations in the cardiac β-myosin heavy chain gene (MYH7); and their noncarrier relatives. Thirty R92W_TNNT2 carriers, 51 MYH7 mutation carriers, and 68 of their noncarrier relatives were subjected to bicycle ergonometric exercise testing to assess blood pressure response to, as well as heart rate recovery after, exercise. Additional echocardiographic and demographic details were documented for all participants. R92W_TNNT2 carriers demonstrated significantly more abnormal blood pressure responses to exercise (P = .021; odds ratio 3.03; confidence interval 1.13–8.12) and smaller increases in systolic blood pressure than MYH7 mutation carriers or related noncarrier control individuals. Although abnormal blood pressure response occurred at similar frequencies in males in all groups (23%–26%), the percentage of R92W_TNNT2 females with abnormal blood pressure response was 64%, compared with 25% for MYH7 and 22% for noncarriers. Therefore, these results show that blood pressure response to exercise is influenced by genotype and gender in patients with HCM.

Short-term systemic effect of electrical muscle stimulation in critically ill patients

BACKGROUND

Our study assessed the short-term effect of electrical muscle stimulation (EMS) of the lower extremities on the thenar muscle microcirculation of patients who are critically ill.

METHODS

Twenty-nine hospital ICU patients (19 men; mean [+/- SD] age, 58 +/- 19 years; mean acute physiology and chronic health evaluation score, 17 +/- 5; mean sequential organ failure assessment score, 9 +/- 3) underwent a 45-min session of EMS of the lower extremities. BP and heart rate were measured, and blood samples were retrieved. Tissue oxygen saturation (Sto(2)) was assessed with near infrared spectroscopy at the thenar muscle with a vascular occlusion before and after EMS. A control group of six patients who were critically ill (4 men; mean age, 50 +/- 19 years) also were included in the study.

RESULTS

The mean Sto(2) did not differ significantly before and after the EMS session (81 +/- 16% vs 83 +/- 16%, respectively). The oxygen consumption rate during vascular occlusion differed significantly before the beginning and at the end of the session (20 +/- 9%/min vs 22 +/- 9%/min, respectively; p < 0.05). The reperfusion rate differed significantly before the beginning and at the end of the session (299 +/- 177%/min vs 375 +/- 182%/min, respectively; p < 0.05). Heart rate increased significantly at the end of the session (94 +/- 16 beats/min vs 99 +/- 16 beats/min, respectively; p < 0.05) as did systolic BP (127 +/- 21 mm Hg vs 133 +/- 23 mm Hg; p < 0.05, respectively). The Sto(2) value did not differ between the two measurements in control patients.

CONCLUSION

The data suggest that EMS has a systemic effect on microcirculation. These results suggest that further studies are needed to explore the potential use of EMS as a preventive and rehabilitation tool in critically ill patients.

Nonneoplastic kidney diseases in adult tumor nephrectomy and nephroureterectomy specimens: common, harmful, yet underappreciated

CONTEXT

Nonneoplastic kidney diseases, such as arterionephrosclerosis and/or diabetic nephropathy, are commonly encountered in tumor nephrectomy and nephroureterectomy specimens. Although any nonneoplastic kidney disease may be encountered in these resection specimens by chance, additional diseases that may be related to the underlying neoplasm or its treatment regimen include thrombotic microangiopathy, Amyloid A amyloidosis, membranous nephropathy, immunoglobulin A nephropathy, membranoproliferative glomerulonephritis, pauci-immune crescentic glomerulonephritis, focal segmental glomerulosclerosis, minimal-change disease, acute interstitial nephritis, and xanthogranulomatous pyelonephritis. Given the morbidity of chronic kidney disease and the relatively favorable 5-year survival rates for urothelial and renal cell carcinomas, accurate evaluation of the nonneoplastic kidney parenchyma is important.

OBJECTIVES

We will discuss our approach for evaluating the nonneoplastic kidney parenchyma in tumor nephrectomy and nephroureterectomy specimens. The pathologic features of the aforementioned kidney diseases as well as pertinent references will be reviewed. The identification of glomerular abnormalities, including mesangial sclerosis or hypercellularity, segmental sclerosis, crescent formation, glomerulitis, or glomerular basement membrane alterations, should lead to additional immunofluorescence and electron microscopic studies. Safeguards to ensure that the nonneoplastic parenchyma is not overlooked include adding this important parameter to synoptic reports and obtaining periodic acid-Schiff and/or Jones methenamine silver stains prior to microscopic evaluation of the neoplasm.

DATA SOURCES

Relevant literature and University of Chicago Medical Center pathology archives.

CONCLUSIONS

The practicing surgical pathologist should be aware of the importance of both correctly classifying the resected renal or urothelial neoplasm and the concomitant nonneoplastic kidney disease that may be present in these specimens.

Post-exercise heart rate recovery independently predicts mortality risk in patients with chronic heart failure

BACKGROUND

Post-exercise heart rate recovery (HRR) is an index of parasympathetic function associated with clinical outcomes in populations with and without documented coronary heart disease. Decreased parasympathetic activity is thought to be associated with disease progression in chronic heart failure (HF), but an independent association between post-exercise HRR and clinical outcomes among such patients has not been established.

METHODS AND RESULTS

We measured HRR (calculated as the difference between heart rate at peak exercise and after 1 minute of recovery) in 202 HF subjects and recorded 17 mortality and 15 urgent transplantation outcome events over 624 days of follow-up. Reduced post-exercise HRR was independently associated with increased event risk after adjusting for other exercise-derived variables (peak oxygen uptake and change in minute ventilation per change in carbon dioxide production slope), for the Heart Failure Survival Score (adjusted HR 1.09 for 1 beat/min reduction, 95% CI 1.05-1.13, P < .0001), and the Seattle Heart Failure Model score (adjusted HR 1.08 for one beat/min reduction, 95% CI 1.05-1.12, P < .0001). Subjects in the lowest risk tertile based on post-exercise HRR (>or=30 beats/min) had low risk of events irrespective of the risk predicted by the survival scores. In a subgroup of 15 subjects, reduced post-exercise HRR was associated with increased serum markers of inflammation (interleukin-6, r = 0.58, P = .024; high-sensitivity C-reactive protein, r = 0.66, P = .007).

CONCLUSIONS

Post-exercise HRR predicts mortality risk in patients with HF and provides prognostic information independent of previously described survival models. Pathophysiologic links between autonomic function and inflammation may be mediators of this association.

Impaired oxygen kinetics in beta-thalassaemia major patients

AIM

Beta-thalassaemia major (TM) affects oxygen flow and utilization and reduces patients' exercise capacity. The aim of this study was to assess phase I and phase II oxygen kinetics during submaximal exercise test in thalassaemics and make possible considerations about the pathophysiology of the energy-producing mechanisms and their expected exercise limitation.

METHODS

Twelve TM patients with no clinical evidence of cardiac or respiratory disease and 10 healthy subjects performed incremental, symptom-limited cardiopulmonary exercise testing (CPET) and submaximal, constant workload CPET. Oxygen uptake (VO2), carbon dioxide output and ventilation were measured breath-by-breath.

RESULTS

Peak VO2 was reduced in TM patients (22.3 +/- 7.4 vs. 28.8 +/- 4.8 mL kg(-1) min(-1), P < 0.05) as was anaerobic threshold (13.1 +/- 2.7 vs. 17.4 +/- 2.6 mL kg(-1) min(-1), P = 0.002). There was no difference in oxygen cost of work at peak exercise (11.7 +/- 1.9 vs. 12.6 +/- 1.9 mL min(-1) W(-1) for patients and controls respectively, P = ns). Phase I duration was similar in TM patients and controls (24.6 +/- 7.3 vs. 23.3 +/- 6.6 s respectively, P = ns) whereas phase II time constant in patients was significantly prolonged (42.8 +/- 12.0 vs. 32.0 +/- 9.8 s, P < 0.05).

CONCLUSION

TM patients present prolonged phase II on-transient oxygen kinetics during submaximal, constant workload exercise, compared with healthy controls, possibly suggesting a slower rate of high energy phosphate production and utilization and reduced oxidative capacity of myocytes; the latter could also account for their significantly limited exercise tolerance.

Effect of biventricular pacing on ventilatory and perceptual responses to exercise in patients with stable chronic heart failure

Despite the growing evidence supporting the use of biventricular cardiac resynchronization therapy (CRT) in patients with chronic heart failure (CHF), the mechanisms whereby acute hemodynamic improvements lead to improved exertional dyspnea are not precisely known. We hypothesized that improved cardiac function and ventilation-perfusion relations following CRT would reduce ventilatory demand, thereby improving dynamic operating lung volumes and enhancing tidal volume expansion during exercise. This, in turn, would be expected to reduce perceived exertional dyspnea and contribute to improved exercise performance. In a randomized, double-blind, crossover study, we compared cardiovascular, metabolic, ventilatory responses (breathing pattern, operating lung volumes, pulmonary gas exchange) and exertional symptoms in seven stable CHF patients who undertook incremental cardiopulmonary cycle exercise test with CRT switched to the “on” (CRTon) or “off” (CRToff) modality. Following CRTon, peak oxygen uptake was significantly increased by 15%, and dyspnea ratings were lower for a given work rate (at work rate of 40 W, dyspnea = 1 ± 0.4 vs. 2.5 ± 0.9 Borg units, P < 0.05) and ventilation (at ventilation of 31 l/min, dyspnea = 2 ± 0.7 vs. 3.3 ± 1.1 Borg units, P < 0.05). CRTon was associated with improvements in ventilatory threshold, oxygen pulse, and oxygen uptake/work rate relationships (10.2 ± 1 vs. 7.9 ± 1.3 ml·min−1·W−1, P < 0.05). CRTon reduced the ventilatory requirement during exercise as well as the steepness of ventilation-CO2 production slope (35 ± 4 vs. 45 ± 7, P < 0.05). Changes in end-expiratory lung volume during exercise were less with CRTon than with CRToff (0.12 vs. 0.37 liter, P < 0.05), and breathing pattern was correspondingly slower and deeper. Biventricular pacing improved all noninvasive indexes of cardiac function and oxygen delivery during exercise. The decreased ventilatory demand, improved dynamic operating lung volumes, and the increased ability to expand tidal volume during exercise are potential factors in the reduction of exertional dyspnea.

Longitudinal cognitive performance in older adults with cardiovascular disease: evidence for improvement in heart failure

BACKGROUND

Cardiovascular disease (CVD) and particularly heart failure (HF) have been associated with cognitive impairment in cross-sectional studies, but it is unclear how cognitive impairment progresses over time in older adults with these conditions.

OBJECTIVE

The aim of this study was to prospectively examine cognitive function in patients with HF versus other forms of CVD.

METHOD

Seventy-five older adults (aged 53-84 years) with CVD underwent Doppler echocardiogram to evaluate cardiac status and 2 administrations of the Dementia Rating Scale (DRS), a test of global cognitive functioning, 12 months apart.

RESULTS

Although DRS performance did not statistically differ between groups at either administration, a significant between-group difference in the rate of cognitive change emerged (lambda = 0.87; F = 10.50; P = .002; omega 2 = 0.11). Follow-up analyses revealed that patients with HF improved significantly on global DRS performance, whereas patients with other forms of CVD remained stable. More specifically, patients with HF showed improvement on subscales of attention, initiation/perseveration, and conceptualization. Exploratory analyses indicated that higher diastolic blood pressure at baseline was associated with improved DRS performance in patients with HF (r = 0.38; P = .02).

CONCLUSIONS

Patients with HF exhibited modest cognitive improvements during 12 months, particularly in attention and executive functioning. Higher diastolic blood pressure at baseline was associated with improvement. These results suggest that cognitive impairment in patients with HF may be modifiable and that improved blood pressure control may be an important contributor to improved function. Further prospective studies are needed to replicate results and determine underlying mechanisms.

New insights into the exercise intolerance of beta-thalassemia major patients

The purpose of our study was assessment of the relative contribution of the systems involved in blood gas exchange to the limited exercise capacity in patients with beta-thalassemia major (TM) using integrative cardiopulmonary exercise testing (CPET) with estimation of oxygen kinetics. The study consisted of 15 consecutive TM patients and 15 matched controls who performed spirometric evaluation, measurement of maximum inspiratory pressure (Pimax) and an incremental symptom-limited CPET on a cycle ergometer. Exercise capacity was markedly reduced in TM patients as assessed by peak oxygen uptake (pVO(2), mL/kg/min: 22.1+/-6.6 vs 33.8+/-8.3; P<0.001) and anaerobic threshold (mL/kg/min: 13.0+/-3.0 vs 18.7+/-4.6; P<0.001) compared with controls. No ventilatory limitation to exercise was noted in TM patients (VE/VCO(2) slope: 23.4+/-3.2 vs 27.8+/-2.6; P<0.001 and breathing reserve, %: 42.9+/-17.0 vs 29.5+/-12.0; P<0.005) and no difference in oxygen cost of work (peak VO(2)/WR, mL/min W: 12.2+/-1.7 vs 12.2+/-1.5; P=NS). Delayed recovery oxygen kinetics after exercise was observed in TM patients (VO(2)/t slope, mL/kg/min(2): 0.67+/-0.27 vs 0.93+/-0.23; P<0.05) that was significantly correlated with Pimax at rest (r: 0.81; P<0.001). The latter was also significantly correlated to pVO(2) (r: 0.84; P<0.001) and inversely correlated to ferritin levels (r: -0.6; P<0.02). Exercise capacity is markedly reduced in TM patients and this reduction is highly associated with the limited functional status of peripheral muscles.

Heart rate recovery after exercise in chronic heart failure: role of vital exhaustion and type D personality

OBJECTIVE

Vital exhaustion and type D personality previously predicted mortality and cardiac events in patients with chronic heart failure (CHF). Reduced heart rate recovery (HRR) also predicts morbidity and mortality in CHF. We hypothesized that elevated levels of vital exhaustion and type D personality are both associated with decreased HRR.

METHODS

Fifty-one patients with CHF (mean age 58+/-12 years, 82% men) and left ventricular ejection fraction (LVEF) < or = 40% underwent standard exercise testing before receiving outpatient cardiac rehabilitation. They completed the 9-item short form of the Maastricht Vital Exhaustion Questionnaire and the 14-item type D questionnaire asking about negative affectivity and social inhibition. HRR was calculated as the difference between heart rate at the end of exercise and 1 min after abrupt cessation of exercise (HRR-1). Regression analyses were adjusted for gender, age, LVEF, and maximum exercise capacity.

RESULTS

Vital exhaustion explained 8.4% of the variance in continuous HRR-1 (p=0.045). For each point increase on the vital exhaustion score (range 0-18) there was a mean+/-SEM decrease of 0.54+/-0.26 bpm in HRR-1. Type D personality showed a trend toward statistical significance for being associated with lower levels of HRR-1 explaining 6.5% of the variance (p<0.08). The likelihood of having HRR-1 < or = 18 bpm was significantly higher in patients with type D personality than in those without (odds ratio=7.62, 95% CI 1.50-38.80).

CONCLUSIONS

Elevated levels of vital exhaustion and type D personality were both independently associated with reduced HRR-1. The findings provide a hitherto not explored psychobiological explanation for poor cardiac outcome in patients with CHF.

Heart rate recovery and prognosis in heart failure patients

The aim of this study is to evaluate the usefulness of heart rate recovery (HRRec) for assessing risk of death in heart failure (HF) patients. Echocardiographic and clinical exercise data were analyzed retrospectively on 712 HF patients (EF < or = 45%). HRRec was calculated as peak exercise heart rate - heart rate at 1 min of active recovery. Patients were followed for all-cause mortality (5.9 +/- 3.3 years follow-up). Groups were identified according to HRRec: group-1 (HRR < or = 4 bpm), group-2 (5 < or = HRR < or = 9 bpm), and group-3 (HRR > or = 10). Kaplan-Meier analysis estimated survival of 91, 64, and 43% (group-1); 94, 76, and 63% (group-2); and 92, 82, and 70% (group-3) at 1, 5, and 10 years, respectively. Ranked HRRec independently predicted mortality after adjusting for age, gender, NYHA class, LVEF and BMI, but was not independent of exercise time, peak V(O)(2) and V(E)/V(CO)(2) at nadir. HRRec is a useful prognostic marker in patients with HF, particularly when gas exchange measures are not available.

A Systematic Review of Exercise Interventions in Patients With Heart Failure

The incidence of heart failure (HF) is increasing as the population ages. Pharmacotherapy is an important component of treatment and yields significant improvements in survival and quality of life. In recent decades, exercise has gradually become accepted as an intervention beneficial to patients with HF, but more information is needed to clarify the effects of exercise and optimize interventions. Therefore, a systematic review of randomized controlled trials published from 1966 to October 2006 was carried out via PubMed. About 69 trials were reviewed, which used as main outcome measures: (a) central hemodynamic parameters, (b) peripheral blood flow, (c) endothelial function, (d) activation of neurohormones and cytokine systems, (e) structure of and metabolism in skeletal muscles, and/or (f) quality of life. Study findings suggest that the favorable physiological responses to exercise might slow some of the pathophysiological progression of HF. However, most of the trials reviewed here were based on relatively small samples and selected participant groups, and the exercise programs varied widely. These limitations and inconsistencies need to be addressed through further studies. Furthermore, reliable strategies for maintaining the positive effects of exercise and extending them to patients' daily life and quality of life are scarce in these trials. These domains need further exploration through rationally designed, large-scale randomized controlled trials.

Exercise Rehabilitation in Pediatric Cardiomyopathy

Children with cardiomyopathy carry significant risk of morbidity and mortality. New research and technology have brought about significant advancements to the diagnosis and clinical management of children with cardiomyopathy. However, currently heart transplantation remains the standard of care for children with symptomatic and progressive cardiomyopathy. Cardiovascular rehabilitation programs have yielded success in improving cardiac function, overall physical activity, and quality of life in adults with congestive heart failure from a variety of conditions. There is encouraging and emerging data on its effects in children with chronic illness and with its proven benefits in other pediatric disorders, the implementation of a program for with cardiomyopathy should be considered. Exercise rehabilitation programs may improve specific endpoints such quality of life, cardiovascular function and fitness, strength, flexibility, and metabolic risk. With the rapid rise in pediatric obesity, children with cardiomyopathy may be at similar risk for developing these modifiable risk factors. However, there are potentially more detrimental effects of inactivity in this population of children. Future research should focus on the physical and social effects of a medically supervised cardiac rehabilitation program with correct determination of the dosage and intensity of exercise for optimal benefits in this special population of children. It is imperative that more detailed recommendations for children with cardiomyopathy be made available with evidence-based research.

Potential autonomic nervous system effects of statins in heart failure

Sympathetic nervous system activation in heart failure, as indexed by elevated norepinephrine levels, higher muscle sympathetic nerve activity and reduced heart rate variability, is associated with pathologic ventricular remodeling, increased arrhythmias, sudden death, and increased mortality. Recent evidence suggests that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor (statin) therapy may provide survival benefit in heart failure of both ischemic and nonischemic etiology, and one potential mechanism of benefit of statins in heart failure is modulation of the autonomic nervous system. Animal models of heart failure demonstrate reduced sympathetic activation and improved sympathovagal balance with statin therapy. Initial human studies have reported mixed results. Ongoing translational studies and outcomes trials will help delineate the potentially beneficial effects of statins on the autonomic nervous system in heart failure.

Effects of cardiac rehabilitation program on exercise capacity and chronotropic variables in patients with orthotopic heart transplant

AIM

To evaluate the effects of home- and hospital-exercise programs on exercise capacity and chronotropic variables in patients with heart transplantation.

METHODS

Forty patients were randomized into two groups either hospital- or home-based exercise program. The patients were compared, before and after the rehabilitation program, with respect to maximal oxygen uptake (pVO(2)), chronotropic variables [heart rate reserve (HRR(e)), heart rate recovery (HRR(1)), and chronotropic response index (CRI)] and Duke Treadmill Score (DTS).

RESULTS

Hospital-based exercise group has shown a significant recovery in post-exercise pVO(2) (pre-exercise 16.73 +/- 3.9 ml/kg/min, post-exercise 19.53 +/- 3.89 ml/kg/min, P = 0.002) and DTS (pre-exercise 4.74 +/- 1.17, post-exercise 5.61 +/- 1.11, P = 0.002). A significant recovery in favor of the hospital-based exercise group was found in HRR(e) (pre-exercise 26.9 +/- 14.6, post-exercise 34.6 +/- 14.6, P = 0.01). No significant change was observed in HRR(1) (pre-exercise -1.38 +/- 1.04, post-exercise -1.21 +/- 1.89, P = 0.49) and CRI (pre-exercise 0.44 +/- 0.23, post-exercise 0.48 +/- 0.20, P = 0.15) in hospital-based exercise group. No significant change was observed in any parameters of home-based group (P > 0.05).

CONCLUSION

A significant recovery was observed both in the functional capacity and the chronotropic response in hospital-based exercise program. Exercise programs that are planned to be performed under supervision in rehabilitation units are useful for the patients with heart transplant in terms of the exercise capacity and chronotropic variables.

Heart rate recovery--a potential marker of clinical outcomes in heart failure patients receiving beta-blocker therapy

BACKGROUND

Heart rate recovery (HRR) within the first few minutes of graded exercise has been associated with impaired clinical outcomes in patients being evaluated for coronary artery disease. HRR is abnormal in patients with heart failure (HF), but has not been associated with clinical outcomes in these patients. The objective of the present study was to determine whether HRR following cardiopulmonary exercise testing (CPET) correlates with peak oxygen consumption (VO(2)), and whether it impacts clinical outcomes, including HF hospitalizations and total mortality, or the need for cardiac transplantation.

METHODS

CPET was performed in 78 patients referred to the Montreal Heart Institute (Montreal, Quebec) with congestive HF between January 2000 and December 2002. All patients had New York Heart Association class II or III HF with a left ventricular ejection fraction of 45% or lower. Mean (+/- SD) age was 53+/-11 years and left ventricular ejection fraction was 27+/-9%. Forty-four per cent had ischemic cardiomyopathy, 88% received beta-blockers and 79% received angiotensin-converting enzyme inhibitors. HRR was defined as the difference from peak exercise HR to HR measured at specific time intervals. HRR was calculated 30 s, 60 s, 90 s and 120 s after exercise.

RESULTS

Mean peak VO(2) was 18.0+/-5.3 mL/kg/min, resting HR was 74+/-13 beats/min and peak HR was 119+/-22 beats/min. HRR measured was 10+/-9 beats/min after 30 s, 20+/-12 beats/min after 60 s, 25+/-15 beats/min after 90 s and 30+/-13 beats/min after 120 s. At 90 s, patients with an HRR below 24 beats/min were more likely to have an HF hospitalization at five-year follow-up (eight hospitalizations [22.2%] versus two hospitalizations [2.7%]; P=0.0134). There was a correlation between peak VO(2) and HRR 90 s and 120 s after completion of the exercise test (r=0.40 after 90 s, P=0.001, and r=0.41 after 120 s, P=0.008).

CONCLUSIONS

In patients with HF, blunted HRR 90 s and 120 s after CPET correlate with peak VO(2) and are associated with increased risk of worsening HF. HRR is easily measured and a useful marker for morbidity in patients with HF.

Effects of exercise training on heart rate recovery in patients with chronic heart failure

BACKGROUND

Heart rate recovery (HRR) is a marker of vagal tone that is associated with survival, but little is known about the effects of exercise training on HRR in patients with heart failure (HF).

METHODS

Twenty-four patients with HF were randomized to a 2-month residential rehabilitation program or to usual care. Symptom-limited exercise testing was performed at baseline and at discharge from the program. Heart rate recovery was expressed as the decline in heart rate from peak exercise through 6 minutes into recovery. In addition, HRR recovery curves were normalized to a range of 1 at peak heart rate and 0 at 6 minutes and adjusted for differences in heart rate reserve, facilitating the comparison of recovery curve shapes between groups.

RESULTS

Mean peak oxygen uptake and oxygen uptake at the lactate threshold increased 26% (P < .05) and 39% (P < .001), respectively, in the exercise group, whereas neither of these responses changed significantly among controls. Heart rate recovery was significantly more rapid in the exercise group after training (main effect 12.6 vs 2.6 beat/min in the trained and control groups, respectively, P = .005). The normalized curves showed that the largest improvement in recovery curve shape occurred in the exercise group, but most of the HRR improvement was accounted for by a widening of the difference between peak and resting heart rate.

CONCLUSION

Exercise training results in a faster HRR in patients with HF. Heart rate recovery, as a simple marker of autonomic function, is an easily acquired response that may be useful for evaluating patient outcomes in cardiac rehabilitation.

Development of a Ventilatory Classification System in Patients With Heart Failure

BACKGROUND

Ventilatory efficiency, commonly assessed by the minute ventilation (VE)-carbon dioxide production (VCO2) slope, is a powerful prognostic marker in the heart failure population. The purpose of the present study is to refine the prognostic power of the VE/VCO2 slope by developing a ventilatory class system that correlates VE/VCO2 cut points to cardiac-related events.

METHODS AND RESULTS

Four hundred forty-eight subjects diagnosed with heart failure were included in this analysis. The VE/VCO2 slope was determined via cardiopulmonary exercise testing. Subjects were tracked for major cardiac events (mortality, transplantation, or left ventricular assist device implantation) for 2 years after cardiopulmonary exercise testing. There were 81 cardiac-related events (64 deaths, 10 heart transplants, and 7 left ventricular assist device implantations) during the 2-year tracking period. Receiver operating characteristic curve analysis revealed the overall VE/VCO2 slope classification scheme was significant (area under the curve: 0.78 [95% CI, 0.73 to 0.83], P<0.001). On the basis of test sensitivity and specificity, the following ventilatory class system was developed: (1) ventilatory class (VC) I: < or = 29; (2) VC II: 30.0 to 35.9; (3) VC III: 36.0 to 44.9; and (4) VC IV: > or = 45.0. The numbers of subjects in VCs I through IV were 144, 149, 112, and 43, respectively. Kaplan-Meier analysis revealed event-free survival for subjects in VC I, II, III, and IV was 97.2%, 85.2%, 72.3%, and 44.2%, respectively (log-rank 86.8; P<0.001).

CONCLUSIONS

A multiple-level classificatory system based on exercise VE/VCO2 slope stratifies the burden of risk for the entire spectrum of heart failure severity. Application of this classification is therefore proposed to improve clinical decision making in heart failure.

The effects of exercise training on the kinetics of oxygen uptake in patients with chronic heart failure

BACKGROUND

Prolonged oxygen uptake kinetics (O2 kinetics), following the onset of a constant workload of exercise has been associated with a poor prognosis in patients with chronic heart failure. This study aimed to determine both continuous and interval training effects on the different O2-kinetics phases in these patients.

DESIGN

Twenty-one patients (60+/-8 years) with stable chronic heart failure participated in a 36-session exercise rehabilitation program (three times weekly). Patients were randomly assigned to interval training (n=11; 100% of peak work rate for 30 s, alternating with 30 s-rest) and to continuous training (n=10; 50% of peak work rate).

METHODS

Before and after the completion of the program, all patients performed both incremental symptom-limited and constant workload submaximal cardiopulmonary exercise tests. Phase I O2-kinetics was evaluated by time (t), from the start of exercise until the onset of decreased respiratory exchange ratio and phase II by the time constant (tau) of the response from the end of phase I until steady state.

RESULTS

After training, there was a significant increase in peak oxygen uptake and peak work rate in both continuous (15.3+/-4.4 vs. 16.6+/-4.5 ml/kg per min; P=0.03 and 81.8+/-40.1 vs. 94.7+/-46.1 W; P=0.03) and interval training groups (14.2+/-3.1 vs. 15.4+/-4.2 ml/kg per min; P=0.03 and 82.5+/-24.1 vs. 93.7+/-30.1 W; P=0.04). Patients who underwent interval training had a significant decrease in t (39.7+/-3.7 to 36.1+/-6.9 s; P=0.05), but not tau (59.6+/-9.4 to 58.9+/-8.5 s; P=ns), whereas those assigned to continuous training had a significant decrease in both t (40.6+/-6.1 to 36.4+/-5.4 s; P=0.01) and tau (63.3+/-23.6 to 42.5+/-16.7 s; P=0.03).

CONCLUSIONS

Exercise training improves O2 kinetics in chronic heart failure patients. Both continuous and interval training improve phase I O2-kinetics, but continuous training results in superior improvement of the phase II O2-kinetics, an indirect index of muscle oxidative capacity.

Effect of acetylcholinesterase inhibition with pyridostigmine on cardiac parasympathetic function in sedentary adults and trained athletes

Heart rate variability and postexercise heart rate recovery are used to assess cardiac parasympathetic tone in human studies, but in some cases these indexes appear to yield discordant information. We utilized pyridostigmine, an acetylcholinesterase inhibitor that selectively augments the parasympathetic efferent signal, to further characterize parasympathetic regulation of rest and postexercise heart rate. We measured time- and frequency-domain indexes of resting heart rate variability and postexercise heart rate recovery in 10 sedentary adults and 10 aerobically trained athletes after a single oral dose of pyridostigmine (30 mg) and matching placebo in randomized, double-blind, crossover trial. In sedentary adults, pyridostigmine decreased resting heart rate [from 66.7 (SD 12.6) to 58.1 beats/min (SD 7.6), P = 0.005 vs. placebo] and increased postexercise heart rate recovery at 1 min [from 40.7 (SD 10.9) to 45.1 beats/min (SD 8.8), P = 0.02 vs. placebo]. In trained athletes, pyridostigmine did not change resting heart rate or postexercise heart rate recovery when compared with placebo. Time- and frequency-domain indexes of resting heart rate variability did not differ after pyridostigmine versus placebo in either cohort and were not significantly associated with postexercise heart rate recovery in either cohort. The divergent effects of pyridostigmine on resting and postexercise measures of cardiac parasympathetic function in sedentary subjects confirm that these measures characterize distinct aspects of cardiac parasympathetic regulation. The lesser effect of pyridostigmine on either measure of cardiac parasympathetic tone in the trained athletes indicates that the enhanced parasympathetic tone associated with exercise training is at least partially attributable to adaptations in the efferent parasympathetic pathway.