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Abnormal baroreflex control of heart rate in decompensated congestive heart failure and reversal after compensation
J A Marin-Neto1, A O Pintya, L Gallo Júnior
1Cardiac Catherization Laboratory, Hospital das Clinicas of the Medical School of Ribeirão Preto, University of São Paulo, Brazil.
Insights
Impaired heart rate control in congestive heart failure (CHF) can improve with treatment. Compensating for severe CHF reversed abnormalities in baroreflex control of heart rate, suggesting a reversible component.
Area of Science:
- Cardiology
- Autonomic Nervous System Research
Background:
- Congestive heart failure (CHF) is associated with impaired baroreflex control of heart rate (HR).
- The reversibility of this autonomic dysfunction in severe CHF is not well understood.
Purpose of the Study:
- To investigate whether the derangement in baroreflex control of HR in patients with severe congestive heart failure is reversible.
- To assess cardiac chronotropic control before and after therapeutic compensation.
Main Methods:
- Evaluated 10 patients with class IV chronic CHF before and after compensation.
- Compensation was achieved through bed rest, salt restriction, diuretics, and vasodilators.
- Assessed heart rate responses to pharmacological (atropine) and physiological (handgrip, head-up tilt) autonomic stimuli, and baroreflex sensitivity using phenylephrine and amyl nitrate.
Main Results:
- Compensation significantly reduced CHF symptoms, body weight, and congestion.
- Heart rate responses to atropine, handgrip, and head-up tilt significantly improved post-compensation (p < 0.01).
- Baroreflex sensitivity to phenylephrine and amyl nitrate also showed significant improvement (p < 0.05).
Conclusions:
- Impaired baroreflex control of heart rate in severe congestive heart failure has a reversible component.
- Reversibility may be linked to the reduction of congestive effects.
- Therapeutic compensation can restore autonomic cardiovascular regulation in severe CHF.
Abstract:
Congestive heart failure (CHF) causes impairment of baroreflex control of heart rate (HR). To determine if this derangement is reversible, the cardiac chronotropic control was assessed in 10 patients with class IV chronic CHF of various etiologies before and after compensation achieved by bed rest, salt restriction, diuretics and vasodilators. Mean time between the 2 studies was 15 +/- 3 days. The management was modified 3 days before the second autonomic evaluation, so as to reestablish the same diet and pharmacologic conditions of the previous study. Compensation led to significant reduction in symptom-based class, body weight, and pulmonary and systemic congestion. Mean +/- standard error of the mean HR responses (beats/min) before and after compensation were, respectively: (1) to atropine (0.04 mg/kg): 10 +/- 2 and 27 +/- 2 (p less than 0.01); (2) to handgrip (30% maximum capacity, 1 minute): 9 +/- 2 and 19 +/- 3 (p less than 0.005); (3) to headup tilt (5 minutes): 4 +/- 3 and 20 +/- 4 (p less than 0.005). Mean +/- standard error of the mean baroreflex sensitivity (ms/mm Hg) of RR responses to phenylephrine and amyl nitrate-induced changes in systolic pressure was, respectively, in each condition: phenylephrine, 0.9 +/- 0.2 and 8 +/- 2.3 (p less than 0.05); amyl nitrate, 0.3 +/- 0.2 and 4.1 +/- 1.1 (p less than 0.05). A significant correlation between improvement in HR responses to atropine and tilt and changes in body weight was obtained. These findings show a reversible component of impaired baroreflex control of HR in severe CHF, possibly due to its congestive effects.