OBJECTIVE To establish the prevalence of chronotropic incompetence in a cohort of patients with chronic heart failure (CHF) taking modern medications for heart failure, and whether this affected exercise capacity and predicted prognosis. METHODS Heart rate response to exercise was examined in 237 patients with CHF in sinus rhythm, who were compared with 118 control volunteers. The percentage ...

A clear association between chronotropic incompetence and increased mortality has been established by a variety of studies in patients with coronary artery disease as well as in healthy individuals. These results gave rise to speculation that rate responsive stimulation might improve prognosis in pacemaker (PM) patients with concomitant chronotropic incompetence. To date, however, no study was ...

In blood-perfused isolated canine atrium preparations, single injections of dibutyryl cyclic AMP at a dose range of 1 to 30 mg were made into the cannulated sinus node artery. At doses above 3 mg, dibutyryl cyclic AMP induced a biphasic chronotropic and inotropic response; there was a slight and rapid negative chronotropic and inotropic response, followed by a long-lasting positive chronotropic...

BACKGROUND Both an impaired capacity to increase heart rate during exercise testing (chronotropic incompetence), and a slowed rate of recovery following exercise (heart rate recovery) have been shown to be associated with all-cause mortality. It is, however, unknown which of these responses more powerfully predicts risk, and few data are available on their association with cardiovascular mortal...

This study evaluated the chronotropic and inotropic responses to glucagon in spontaneously beating isolated right atria of rat heart. For comparison, we also investigated the effects resulting from stimulating β-adrenoceptors with isoproterenol in this tissue. Isoproterenol increased both atrial frequency and contractility but glucagon only enhanced atrial rate. The transcript levels of glucago...

OBJECTIVE To investigate the functional significance of chronotropic incompetence during dobutamine stress echocardiography. PATIENTS AND METHODS The functional significance of chronotropic incompetence was evaluated during dobutamine stress echocardiography in 512 patients without beta blocker treatment who underwent dobutamine stress echocardiography (up to 40 microg/kg/min) and completed t...

CONTEXT Chronotropic incompetence, an attenuated heart rate response to exercise, is a predictor of all-cause mortality in healthy populations. This association may be independent of exercise-induced myocardial perfusion defects. OBJECTIVE To examine the prognostic significance of chronotropic incompetence in a low-risk cohort of patients referred for treadmill stress testing with thallium im...

OBJECTIVES This study sought to examine the prognostic importance of chronotropic incompetence among patients referred for stress echocardiography. BACKGROUND Although chronotropic incompetence has been shown to be predictive of an adverse prognosis, it is not clear if this association is independent of exercise-induced myocardial ischemia. METHODS Consecutive patients (146 men and 85 women...

Christou DD, Seals DR. Decreased maximal heart rate with aging is related to reduced -adrenergic responsiveness but is largely explained by a reduction in intrinsic heart rate. J Appl Physiol 105: 24–29, 2008. First published May 15, 2008; doi:10.1152/japplphysiol.90401.2008.—A decrease in maximal exercise heart rate (HRmax) is a key contributor to reductions in aerobic exercise capacity with a...

We investigated the effects of a neuropeptide, pituitary adenylate cyclase-activating polypeptide- (PACAP) 27, on the sinoatrial nodal pacemaker activity and the mechanisms for the cardiac effects of PACAP-27 in the autonomically decentralized heart of the anesthetized dog. PACAP-27 (0.01-0.3 nmol) injected into the sinus node artery increased followed by decreased sinus rate. PACAP-27 (0.1 and...