The effect of Egyptian cobra (Naja haje) on BP and chronotropic response
of the heart might be dose dependent as reported in a study based on an experiment conducted on rats (10).
The principal findings of this study were the following: (1) HRR1 was significantly lower in IPAH than that in normal subjects; (2) CRI was detected in 89.7% IPAH patients (n = 52), 53% with HRR < 16 beats; (3) a decrease in the heart rate recovery after exercise was associated with worse NYHA functional class, impaired chronotropic response
, increased NT-proBNP, and decreased exercise capacity.
Cross-striations, ultrastructure, and chronotropic response
Autoregulation of chronotropic response
of the heart through pacemaker stretch.
(2009) showed that cycling continuously modulates the cardiac chronotropic response
to exercise and that a workload increase during intense exercise further accentuates synchronization between the cardiac and locomotor rhythms.
Results in the form of total exercise time, maximum heart rate, percentage of maximum heart rate achieved, work done in METS, reasons for the termination of the test, exercise tolerance, arrhythmias, hemodynamic response and chronotropic response
Body weight and body mass index of these patients were significantly higher than in those with normal chronotropic response
The study did not include any men who, during testing, had a positive stress test, unstable symptoms, or a left bundle branch block; it also excluded anyone with an implanted pacemaker or impaired chronotropic response
Integrity of the vagus nerve fibers in rats with acute chagasic myocarditis has also been examined by direct stimulation; it was demonstrated that, at low frequency stimulation, chagasic animals had a lower negative chronotropic response
as compared with control animals, while at high frequency stimulation, the negative chronotropic response
In addition to the fluctuations in heart rate that occur with labour pain, pregnancy attenuates the chronotropic response
The similarity of hawthorn's effect to that of the [beta]-adrenergic antagonist propranolol was further investigated by determining the effect of both substances on the chronotropic response
of cardiomyocytes to epinephrine, a [beta]-adrenergic agonist.
In one study of nearly 10,000 patients, those with normal heart rate recovery; chronotropic response
, and a low-risk Duke Treadmill Score had a 0.2% annual mortality risk.