BACKGROUND The heart rate (HR) achieved at the end of an exercise test (ET) is called maximal HR and is known to have clinical and epidemiological relevance. For its correct measurement, it is necessary that the ET be truly maximal. OBJECTIVE To evaluate the influence of a history of intense physical activity and/or participation in sports competitions during youth on the maximal HR (% of age...

OBJECTIVE To evaluate the chronotropic response to exercise during immediate and late postoperative period after atrial fibrillation and mitral valve surgical treatment by different techniques. METHODS Prospective controlled clinical study of 42 patients presenting chronic AF associated mitral valve disease, who underwent surgery by the techniques of pulmonary veins isolation (n=16), Modified...

Inositol 1,4,5-trisphosphate (IP3) is one of the second messengers capable of releasing Ca2+ from sarcoplasmic reticulum/ER subcompartments. The mRNA encoding the intracellular IP3 receptor (Ca2+ channel) has been detected in low amounts in the heart of various species by Northern blot analysis. The myocardium, however, is a heterogeneous tissue composed of working myocytes and conduction syste...

Much of the information available in the literature on physiological responses during Enduro motorcycling is related to heart rate (HR) and blood lactate (BLa). The aim of this work was to investigate the hemodynamic changes that occur during a 10-min session of Enduro motorcycling. Fifteen skilled riders were enrolled on the study and all participants underwent an Enduro-motorcycling session o...

The right atrium isolated from the dog heart was perfused through the cannulated sinus node artery with heparinized arterial blood led from a support dog anesthesized with 30 mg/Kg of sodium pentobarbital. When adenosine was administered into the sinus node artery, negative chronotropic and inotropic effects were dose-relatedly induced. The threshold dose for inducing the negative ones was 0.3 ...

Using an isolated working heart preparation we show that angiotensin II (ANG II), at concentrations of 10(-10)-10(-7) mol l(-1), elicits negative chronotropism and inotropism in the freshwater eel Anguilla anguilla. The negative inotropism was insensitive to losartan and CGP42112 (AT(1) and AT(2) ANG II receptor antagonists, respectively), and was abrogated by the AT(1) receptor antagonist CV11...

I have read the article entitled “Is cardiac resynchronisation therapy feasible, safe and beneficial in the very elderly?” by Olechowski, et al. with great interest, recently published in Journal of Geriatric Cardiology. The investigators reported that implantation of cardiac resynchronisation therapy (CRT) is feasible and safe in very elderly despite extensive co-morbidity. I would like to emp...

OBJECTIVES The purpose of this study was to assess the value of preoperative cardiac testing in intermediate-risk patients receiving beta-blocker therapy with tight heart rate (HR) control scheduled for major vascular surgery. BACKGROUND Treatment guidelines of the American College of Cardiology/American Heart Association recommend cardiac testing in these patients to identify subjects at inc...

Presynaptic alpha2-adrenergic receptors are known to exert feedback inhibition on norepinephrine release from the sympathetic nerve terminals. To elucidate the dynamic characteristics of the inhibition, we stimulated the right cardiac sympathetic nerve according to a binary white noise signal while measuring heart rate (HR) in anesthetized rabbits (n = 6). We estimated the transfer function fro...

We have previously demonstrated that the beneficial effect of cardioselective beta-blockade on exercise-induced ischemia is due entirely to negative chronotropism. Therefore we studied the effect of a new bradycardiac agent (UL-FS 49) in 10 dogs with chronic coronary artery stenosis produced by an ameroid constrictor. Regional myocardial function (sonomicrometers, wall thickness) and blood flow...