Heart rate variability and diastolic heart failure.
ABSTRACT 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.
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ABSTRACT: There is sound experimental evidence that cardiovascular sympathetic afferent fibers mediate cardiovascular reflexes largely excitatory in nature with positive-feedback characteristics. This afferent neural channel is likely to normally participate in the neural regulation of cardiovascular function. The hypothesis, which is the core of this article, is that in some pathophysiological conditions, sympathetic overactivity may be partly due to an emerging excitatory reflex action of cardiovascular sympathetic afferents. In fact, the early phase of congestive heart failure can be characterized by an increase in arterial pressure and heart rate and/or by a diastolic dysfunction, leaving unchanged the cardiac output; in these conditions, in which no baroreceptor deactivation should occur, it is possible that cardiovascular sympathetic afferents with sensory endings in the thoracic low-pressure areas, highly responsive to volume loading, are responsible for mediating the reflex sympathetic excitation. Similarly, during acute myocardial infarction, ventricular sympathetic afferents are likely to mediate a reflex sympathetic overactivity, which is known to facilitate sudden death. Finally, numerous reports have described in essential arterial hypertension an increased sympathetic activity that may be due, at least in part, to the reinforcing action of sympathosympathetic reflexes. Thus, in pathophysiological conditions, cardiovascular sympathetic afferents would mediate a reflex sympathetic overactivity independently of baroreceptive mechanisms, and such an absence of a homeostatic purpose would provide a better rationale for some beneficial effects of therapeutic correction.Hypertension 02/2002; 39(1):63-8. · 6.87 Impact Factor
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ABSTRACT: A high degree of heart rate (HR) variability is found in compensated hearts with good function, whereas HR variability can be decreased with severe coronary artery disease, congestive heart failure, aging and diabetic neuropathy. To test the hypothesis that HR variability is a predictor of long-term survival after acute myocardial infarction (AMI), the Holter tapes of 808 patients who survived AMI were analyzed. Heart rate variability was defined as the standard deviation of all normal RR intervals in a 24-hour continuous electrocardiogram recording made 11 +/- 3 days after AMI. In all patients demographic, clinical and laboratory variables were measured at baseline. Mean follow-up time was 31 months. Of all Holter variables measured, HR variability had the strongest univariate correlation with mortality. The relative risk of mortality was 5.3 times higher in the group with HR variability of less than 50 ms than the group with HR variability of more than 100 ms. HR variability remained a significant predictor of mortality after adjusting for clinical, demographic, other Holter features and ejection fraction. A hypothesis to explain this finding is that decreased HR variability correlates with increased sympathetic or decreased vagal tone, which may predispose to ventricular fibrillation.The American Journal of Cardiology 03/1987; 59(4):256-62. · 3.21 Impact Factor
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ABSTRACT: To describe the prognosis of individuals with idiopathic dilated cardiomyopathy in a population-based sample and to compare this with the prognosis of patients in a previous referral center case series of idiopathic dilated cardiomyopathy. Cohort study. Population-based in Olmsted County, Minnesota. Forty residents of Olmsted County, Minnesota with idiopathic dilated cardiomyopathy initially diagnosed between 1975 and 1984 who were followed through 1 July 1989 and 104 patients from a Mayo Clinic referral case series from 1960 to 1973. Survival for the population-based cohort at 1 year and 5 years. Survival at 1 year differed dramatically between the population-based cohort and the referral case series at 1 year (95% compared with 69%, respectively) and at 5 years (80% compared with 36%, respectively) (P less than 0.001). Long-term survival for the population-based cohort was nonetheless impaired when compared with an age- and sex-matched cohort, that is, the 1980 Minnesota white population (8-year survival: observed, 58% compared with expected, 83%; P less than 0.001). Among community patients, older age (adjusted Cox model hazard ratio for 10-year increase in age, 1.59; 95% CI, 1.08 to 2.35) and lower left ventricular ejection fraction (adjusted hazard ratio for 10% decrease, 1.90; CI, 1.04 to 3.50) were independently associated with impaired survival. These population-based data challenge the clinical perception of the clinical course of idiopathic dilated cardiomyopathy based on referral practice prognostic studies and suggest that the clinical course of this condition may be more favorable than previously recognized.Annals of internal medicine 08/1992; 117(2):117-23. · 13.98 Impact Factor