Diastolic heart failure accounts for up to 40% of patients with congestive heart failure (CHF), and is associated with a better prognosis as compared to patients with systolic dysfunction. Nevertheless, patients with diastolic dysfunction have a significantly higher mortality as compared to the normal population. Reduced heart rate variability (HRV), a marker of autonomic dysfunction, is associated with increased mortality in patients with systolic heart failure. We therefore sought to determine to what extent HRV is altered in a population of patients with diastolic heart failure. Twenty-four hour ambulatory (Holter) recordings were performed in 19 consecutive patients with diastolic heart failure, in 9 patients with systolic heart failure, as well as in 9 healthy volunteers (normal controls). Time and frequency domain HRV variables were obtained for all three groups of patients. Both Time and Frequency domain variables were found to be reduced in both heart failure groups compared to normal controls. When compared with each other, patients with diastolic function had relatively higher values of HRV variables, compared to those with systolic dysfunction (SDNN, Total power, ULF power, all P <or= 0.05). Patients with diastolic dysfunction have reduced HRV, suggesting a disturbed sympathetic-parasympathetic balance. Nevertheless, values for HRV are not as profoundly reduced as in patients with systolic dysfunction. The relative preservation of sympathetic-parasympathetic balance may explain the better prognosis in this patient population.
[Show abstract][Hide abstract] ABSTRACT: Both left ventricular (LV) hypertrophy and decreased autonomic function are predictors of adverse cardiac events. Patients with diabetic nephropathy have an excess cardiovascular risk. The authors determined heart rate variability from 24-hour ambulatory electrocardiographic recordings and measures of LV mass with systolic and diastolic function from echocardiograms. Patients with diabetic nephropathy (n=16) were seen weekly for insulin and hypertension management. Glycohemoglobin decreased from 9.5+/-0.4% to 8.3+/-0.4% (p=0.01), and advanced glycated end products decreased from 12.1+/-2.2 to 7.4+/-1.2 units (p=0.03). Mean arterial pressure and body weight did not change. Serum creatinine increased (1.8+/-0.1 mg/dL to 2.0+/-0.2 mg/dL; p=0.03). The authors used a panel of markers of baseline heart rate variation to assess autonomic function. When covariance of the heart rate interval results were evaluated, the group below the median was found to have a significant decrease in LV mass, from 230 g to 184 g (p=0.013); the group above the median had an increase (182 g to 193 g; p=0.5329). Baseline covariance of the heart rate interval predicted 12-month changes in LV mass in 13 of 16 patients (predictive accuracy, 81%). Improvement in measures of heart rate variation correlated with a decrease in LV mass. Parallel improvement of LV mass and autonomic function suggests a common mechanism, allowing for prediction of LV mass improvement through analysis of baseline heart rate variation.
[Show abstract][Hide abstract] ABSTRACT: Disturbances in cardiovascular neural regulation, influencing both disease course and survival, progress as heart failure worsens. Heart failure due to left ventricular systolic dysfunction has long been considered a state of generalized sympathetic activation, itself a reflex response to alterations in cardiac and peripheral hemodynamics that is initially appropriate, but ultimately pathological. Because arterial baroreceptor reflex vagal control of heart rate is impaired early in heart failure, a parallel reduction in its reflex buffering of sympathetic outflow has been assumed. However, it is now recognized that: 1) the time course and magnitude of sympathetic activation are target organ-specific, not generalized, and independent of ventricular systolic function; and 2) human heart failure is characterized by rapidly responsive arterial baroreflex regulation of muscle sympathetic nerve activity (MSNA), attenuated cardiopulmonary reflex modulation of MSNA, a cardiac sympathoexcitatory reflex related to increased cardiopulmonary filling pressure, and by individual variation in nonbaroreflex-mediated sympathoexcitatory mechanisms, including coexisting sleep apnea, myocardial ischemia, obesity, and reflexes from exercising muscle. Thus, sympathetic activation in the setting of impaired systolic function reflects the net balance and interaction between appropriate reflex compensatory responses to impaired systolic function and excitatory stimuli that elicit adrenergic responses in excess of homeostatic requirements. Recent observations have been incorporated into an updated model of cardiovascular neural regulation in chronic heart failure due to ventricular systolic dysfunction, with implications for the clinical evaluation of patients, application of current treatment, and development of new therapies.
Journal of the American College of Cardiology 08/2009; 54(5):375-85. DOI:10.1016/j.jacc.2009.03.061 · 16.50 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Cardiovascular autonomic neuropathy is a common form of autonomic dysfunction in diabetes mellitus (DM) and associates abnormalities in heart rate control and in vascular dynamics. This study evaluates the impact of diabetes mellitus on left ventricular diastolic dysfunction (LVDD) and heart rate variability in a group of type 2 diabetes mellitus without signs of cardiovascular disease. The study group consisted of 58 patients, aged 61 ± 8 years, diagnosed with type 2 DM. The subjects were selected from a series of 104 consecutive diabetic patients. All the subjects were on oral therapy or on diet for DM, and ECG was normal for all the subjects. The control group consisted of 45 healthy subjects, matched for age and sex. Heart rate variability was measured using a 24-h ECG monitoring system, and standard 2D and Doppler echocardiography was performed in all the subjects. There are significant differences between groups regarding disease duration, longer in patients with impaired relaxation (11.22 ± 9.17 vs. 8.31 ± 8.95 years), and disease control, worse in impaired relaxation group. Heart rate in impaired relaxation group is significantly higher than in controls, and higher, but not significantly, when compared with normal group (91 ± 10, vs. 88 ± 11 and 71 ± 11, respectively). Cardiac autonomic neuropathy was associated with LVDD in patients with type 2 DM, but without clinically manifest heart disease. Twenty-four-hour ECG monitoring and echocardiography can detect diabetic cardiomyopathy in early stages and should be performed in all subjects.
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