Arlene B. Levine

EFFECTS OF CARDIAC SYMPATHETIC INNERVATION ON CORONARY BLOOD FLOW

BACKGROUND The role of cardiac sympathetic nerves in regulating coronary blood flow is controversial. We sought to determine the degree to which cardiac efferent sympathetic signals modulate coronary blood flow. The heterogeneous sympathetic reinnervation in transplanted hearts provides a model for studying the vasomotor responses to adrenergic stimulation in reinnervated and denervated coronary territories of the same heart. METHODS We studied 14 cardiac-transplant recipients who had normal coronary arteries and no evidence of rejection and 8 normal subjects. We used positron-emission tomography with [(11)C]hydroxyephedrine, an analogue of norepinephrine, to delineate sympathetic innervation. Using [(13)N]ammonia, we measured myocardial blood flow at rest, during adenosine-induced hyperemia, and in response to sympathetic stimulation induced by cold pressor testing. RESULTS In the transplant recipients, the uptake of [(11)C]hydroxyephedrine was greater in the territory served by the left anterior descending artery (0.15+/-0.01) than in those served by the right coronary artery (0.07+/-0.01, P<0.001) or the circumflex artery (0.09+/-0.01, P<0.001). The basal flow was similar in all three regions, as was the percent increase in flow during hyperemia. However, the increase in flow in response to cold pressor testing was higher in the territory of the left anterior descending artery (46+/-10 percent) than in those of the right coronary artery (16+/-5 percent, P=0.01) or the circumflex artery (23+/-6 percent, P=0.06), although the changes in hemodynamics and levels of circulating catecholamines were similar. No such regional differences were observed in the normal subjects. CONCLUSIONS Increases in coronary blood flow in response to sympathetic stimulation correlated with the regional norepinephrine content in the cardiac sympathetic-nerve terminals. These findings suggest that cardiac adrenergic signals play an important part in regulating myocardial blood flow.

Effects of exercise training on chronotropic incompetence in patients with heart failure.

OBJECTIVE To describe the effects of exercise training on chronotropic incompetence in patients with stable heart failure, as measured by their inability to achieve a peak exercise heart rate greater than 85% of maximum. BACKGROUND Exercise intolerance and chronotropic incompetence are characteristic of patients with heart failure. Exercise training improves exercise capacity in these patients; however, to what extent reversal of chronotropic incompetence contributes to such a response remains uncertain. METHODS Fifty-one patients undergoing standard medical therapy were randomly assigned to a 24-week exercise training program or a no exercise control group. Twenty-one of 26 patients assigned to the exercise group and 22 of 25 control patients completed the study. Peak oxygen consumption, resting and exercise plasma norepinephrine level, and quality of life (Living With Heart Failure Questionnaire) were assessed. RESULTS A significant (P <.05) increase in peak heart rate was observed in the exercise group (9 +/- 3 beats/min) when compared with the control group (1 +/- 3 beats/min). Among exercise-trained patients with chronotropic incompetence at baseline (n = 14), the increase in peak heart rate at week 24 was 12 +/- 3 beats/min. Peak oxygen consumption was significantly (P <.05) increased in the exercise group (204 +/- 57 mL/min) versus the control group (72 +/- 33 mL/min). Health-related quality of life was not significantly changed with exercise training. Twenty-four weeks of exercise training induced a greater (P <.05) reduction in plasma norepinephrine at rest and during exercise in patients with a nonischemic cardiomyopathy versus those with ischemic cardiomyopathy. CONCLUSIONS Exercise training results in an increase in peak heart rate and partial reversal of chronotropic incompetence among patients with stable heart failure. These responses contribute, in part, to the exercise training-induced increase in exercise capacity that occurs in these patients.

Posttraumatic Stress Disorder and Cardiometabolic Disease

The need for addressing posttraumatic stress disorder (PTSD) among combat veterans returning from Afghanistan and Iraq is a growing public health concern. Current PTSD management addresses psychiatric parameters of this condition. However, PTSD is not simply a psychiatric disorder. Traumatic stress increases the risk for inflammation-related somatic diseases and early mortality. The metabolic syndrome reflects the increased health risk associated with combat stress and PTSD. Obesity, dyslipidemia, hypertension, diabetes mellitus, and cardiovascular disease are prevalent among PTSD patients. However, there has been little appreciation for the need to address these somatic PTSD comorbidities. Medical professionals treating this vulnerable population should screen patients for cardiometabolic risk factors and avail themselves of existing preventive diet, exercise, and pharmacologic modalities that will reduce such risk factors and improve overall long-term health outcomes and quality of life. There is the promise that cardiometabolic preventive therapy complementing psychiatric intervention may, in turn, help improve the posttraumatic stress system dysregulation and favorably impact psychiatric and neurologic function.

Characterization of the Role of Nitric Oxide and Its Clinical Applications

Nitric oxide (NO) has long been known as endothelium-derived relaxing factor. It is a vasodilator, modulating vascular tone, blood pressure and hemodynamics, a role exploited by nitrate donor therapy for angina, heart failure, pulmonary hypertension and erectile dysfunction. In addition, its powerful antioxidant, anti-inflammatory and antithrombotic actions are antiatherogenic with antiatherothrombotic impact. NO signaling modulates skeletal muscle and myocardial contractility and metabolism and is intimately linked with insulin signaling. Vascular and muscle NO signaling coordinate skeletal muscle and myocardial energy demand with supply and are critical for both carbohydrate and fatty acid total-body homeostasis. NO signaling in mitochondria underlies much of NO’s metabolic effect, which, at low physiologic levels, links cellular energy demand with mitochondrial energy supply, while beneficially affecting mitochondrial oxidative stress and calcium handling. Mitochondria are also the site for the life-threatening deleterious effects arising from inflammation-related excessive NO levels. NO-deficient states are characterized by cell senescence, oxidative stress, inflammation, endothelial dysfunction, vascular disease, insulin resistance and type 2 diabetes mellitus. NO-enriching therapy would be expected to be of benefit not only for its hemodynamic but also for its metabolic impact. In contrast, strategies are needed to curtail excessive NO in states such as septic shock.

Paradoxical hypertension after reversal of heart failure in patients treated with intensive vasodilator therapy.

Hypertension is a major cause of heart failure, evolving from left ventricular hypertrophy to systolic and diastolic dysfunction. Although effective heart failure therapy has been associated with a lowering or no change in systemic arterial blood pressure in long-term follow-up, this study describes the symptomatic, clinical, and left ventricular functional response of a subgroup of heart failure patients with a prior history of hypertension who demonstrated a paradoxical hypertensive response despite high-dose vasodilator therapy. We prospectively identified 45 patients with a past history of hypertension who had become normotensive with symptomatic heart failure. Of these 45 heart failure patients, 12 became hypertensive while receiving therapy in follow-up, with systolic blood pressure > or = 140 mm Hg (Group A). The remaining 33 patients did not have a hypertensive response to therapy (Group B). In the 12 Group A patients, 60+/-10 years old, with symptomatic heart failure for 6.3+/-4.3 years, vasodilator therapy was intensified in the 2.0+/-0.5 years of follow-up, achieving final doses of enalapril 78+/-19 mg and isosorbide dinitrate 293 +/-106 mg per day. New York Heart Association classification improved from 2.9+/-0.8 to 1.3+/-0.5 (P < or = .0001), with a reduction in heart-failure-related hospitalizations. Left ventricular ejection fraction increased from 17+/-6% to 40+/-10% (P < .0001). Follow-up blood pressure at 1 to 3 months was unchanged. However, both systolic and diastolic blood pressure increased at final follow-up, rising from 116+/-14 to 154+/-13 mm Hg (P = .0001) and from 71+/-9 to 85+/-14 mm Hg (P = .004), respectively. Renal function remained unchanged. Although both groups had similar clinical responses, there were more blacks and women in the hypertensive Group A. Effectively, 12 of 45 (27%) heart failure patients with an antecedent history of hypertension demonstrated a paradoxical hypertensive response to vasodilator therapy. The recurrence of hypertension in a significant portion of patients successfully treated for heart failure has important clinical implications.

Reversal of heart failure remodeling in women.

Epidemiological studies suggest that women with heart failure differ from men with heart failure in that their survival is better. Therapeutic trials have not clearly demonstrated a survival benefit for women. This study was to determine the tolerance for high doses of angiotensin-converting enzyme (ACE) inhibitor-nitrates in women versus men and to compare their symptomatic response, exercise tolerance, and ventricular functional improvement over 1 year. Eighty-eight sequential patients with heart failure, 54 men and 34 women with left ventricular ejection fraction < or = 35%, were prospectively followed for 1 year. For all patients, ACE inhibitor-nitrate therapy was intensified. Each patient had three 6-monthly echocardiograms at baseline, at 6 months, and at 1 year, and metabolic stress testing. Patients were 57.3 +/- 12.3 years old, with New York Heart Association (NYHA) class severity 2.6 +/- 1.0. Lisinopril dosages were raised from 14 +/- 14 mg/day to 57 +/- 26 mg/day, isosorbide mononitrate from 15 +/- 27 mg/day to 126 +/- 72 mg/day, and carvedilol (n = 34) to 17 +/- 16 mg/day. Women and men were epidemiologically comparable, with similar baseline echocardiographic parameters (left ventricular ejection fraction 19% +/- 7% versus 17% +/- 6%, respectively). Both tolerated up-titration in medical therapy. Final 12-month ejection fractions were equivalent for women and men at 34% +/- 17% and 34% +/- 13%, respectively, with similar improvements in left ventricular diameters. At 1 year, women had higher resting heart rates and remained more symptomatic with lower exercise capacity. However, the relative changes in NYHA status and aerobic capacity were similar for women and men. Thus, both women and men tolerated uptitrated ACE inhibitor-nitrate medical therapy, with comparable reversal of heart failure remodeling. Although women continued to be more symptomatic than men, relative improvements in symptomatic status, in exercise capacity, and in hospitalization rate were equivalent.