[The function of the heart changes in implementation of the diving reactions in humans].
1
Citation
0
Reference
10
Related Paper
Citation Trend
Abstract:
The changes of chronotropic function of the heart and of the myocardium in the implementation of the diving response in humans were studied by the electrocardiographic method. The study involved 80 students aged 18-20 years. Diving simulation was performed by immersing the face in cold water during breath-hold exhale. When the water temperature was 12.3 +/- 2.3 degrees C, average duration of apnea was 31 +/- 11 s. The oxygen content in the exhaled air after apnea was 98.8 +/- 8.7 mm Hg, carbon dioxide--49.1 +/- 3.5 mm Hg. It was observed slowing of the heart rate, mainly due to the increasing of diastole in 41 of the 80 surveyed during simulating diving. But it also can be observed symptoms of conduction deterioration: atrioventricular block type I (22% of reactive type and 29% of the highly reactive type subjects), and exceeds standards QTc-interval prolongation (at 7.5% of the subjects). These responses are adaptive in nature and disappear in the recovery process. But the fact abnormalities of conduction in the myocardium must be considered when using the diving reflex in medical practice, as may be due to a predisposition to a certain pathology of the cardiovascular system.Cite
Respiratory Rate
Cite
Citations (44)
Cite
Citations (33)
Breathing was associated with an elevated heart rate and apnea with lower rates, the pattern and level of change varying with activity and breathing frequency. Inactive snakes breathing infrequently achieved a low, stable heart called the apneic heart rate, which is distinct from diving bradycardia. Breathing tachycardia occurred in anticipation of the actual initiation of ventilation. Activity caused an elevation in heart rate during apnea. Resting heart rates were similar to those of other diving reptiles but somewhat lower than those of non-diving species, although comparisons were tentative because of the different methodologies used by different investigators. In the evening, breathing tachycardia was reduced; consequently heart rate differences between breathing and apnea were smaller than during the day. The physiological adaptations of marine snakes to their environment seem to consist of quantitative rather than qualitative departures from the basic reptilian mode. * * *
Ophidia
Cite
Citations (14)
Thirty-two former preterm infants (less than or equal to 44 weeks postconceptual age) undergoing inguinal hernia repair were prospectively studied. General inhalational anesthesia with neuromuscular blockade was used. No barbiturates or opioids were given. Infants were randomly divided into two groups. Group 1 received iv caffeine 10 mg/kg immediately after induction of anesthesia. Group 2 received iv saline. Respiratory pattern, heart rate, and SpO2 were monitored using an impedance pneumograph and a pulse oximeter, respectively, for at least 12 h postoperatively. Tracings were analyzed for evidence of apnea, periodic breathing, and/or bradycardia by a pulmonologist unaware of the drug given. None of the patients who received caffeine developed postoperative bradycardia, prolonged apnea, or periodic breathing, and none had postoperative SpO2 less than 90%. In the control group 13 (81%) developed prolonged apnea 4-6 h postoperatively. Fifty percent of the patients had SpO2 less than 90% at the time. This study shows that iv caffeine 10 mg/kg is effective in the control of apnea in otherwise healthy expremature infants between 37 and 44 weeks of postconceptual age. It is still recommended, however, that all infants at risk be monitored for at least 12 h for apnea and bradycardia following general anesthesia.
Periodic breathing
Pulse Oximetry
Cite
Citations (91)
Aims This study aimed to investigate the correlation of heart rate profile during exercise with exercise capacity and heart failure occurrence in patients with atrial fibrillation compared with patients with sinus rhythm. Methods We analyzed 2231 patients (atrial fibrillation: n = 321, sinus rhythm: n = 1910) who underwent a symptom-limited maximal cardiopulmonary exercise test at our institute. Their heart rate profile during exercise was assessed using peak heart rate and chronotropic response; (peak heart rate-resting heart rate)/(220-age-resting heart rate). The endpoint was the occurrence of heart failure events, defined as hospitalization for heart failure or heart failure-related death. Results There were significant positive correlations of peak heart rate and chronotropic response to peak oxygen consumption, both in atrial fibrillation and sinus rhythm. During a median follow-up period of 1262 (interquartile range 974-2921) days, 117 (5.2%) heart failure events were observed. Multivariate analyses showed that peak heart rate and chronotropic response were statistically significant predictors of heart failure events both in atrial fibrillation (peak heart rate: heart rate 0.975, p = 0.002, chronotropic response: heart rate 0.196, p = 0.003) and in sinus rhythm (peak heart rate: heart rate 0.988, p = 0.036, chronotropic response: heart rate 0.347, p = 0.020). Bivariate models showed that compared with chronotropic response, peak heart rate was a stronger predictor of heart failure in atrial fibrillation, whereas the finding was reversed in sinus rhythm. Conclusion The exercise- heart rate profile was significantly related to exercise capacity and future heart failure events, regardless of rhythm. However, the impacts of peak heart rate and chronotropic response on the endpoint varied according to the cardiac rhythm.
Cite
Citations (10)
Cite
Citations (16)
Reflex bradycardia
Embryonic heart
Cite
Citations (0)
Heart rate variability was studied in 41 patients (aged 48 ± 12 years) with congestive heart failure secondary to idiopathic dilated cardiomyopathy. All patients underwent a treadmill exercise test and 24‐hour Holter ECC monitoring. Chronotropic incompetence was defined as the failure to achieve > 80% of the predicted maximal heart rate response given by 220 – age (years) at peak exercise. Spectral heart rate variability was analyzed from 24‐hour Holter ECCs and was expressed as total (0.01–1.00 Hz), low (0.04–0.15 Hz), and high (0.15–0.40 Hz) frequency components. The standard deviation of all normal RR intervals (SDNN) was also computed. Chronotropic incompetence was observed in ten patients. Peak oxygen consumption was significantly lower in patients witb chronotropic incompetence compared with those without chronotropic incompetence. The total (5.11 ± 1.26 In [ms 2 ] vs 6.41 ± 0.92 In [ms 2 ]; P = 0.009) and low (3.38 ± 1.65 In [ms 2 ] vs 5.45 ± 1.34 In [ms 2 ];P = 0.003), but not the high (3.42 ± 1.04 In [ms 2 ] vs 4.00 ± 1.12 in [ms 2 ]; P = 0.249) frequency components of heart rate variability were significantly lower in patients with chronotropic incompetence, although there was no significant difference in mean heart rate (88 ± 20 beats/min vs 86 ± 15 beats/min; P = 0.831) or left ventricular ejection fraction (22%± 10% vs 24%± 10%; P = 0.619). SDNN was also significantly lower in patients with chronotropic incompetence compared witb those without chronotropic incompetence (64 ± 34 ms vs 102 ± 37 ms; P = 0.030). Conclusions: The observation that heart rate variability is significantly decreased in patients with congestive heart failure who have chronotropic incompetence suggests that chronotropic incompetence may relate to an abnormal autonomic influence on the heart in these patients.
Cite
Citations (55)
Our aim was to evaluate electrocardiographic and echocardiographic properties and exercise response of patients with fibromyalgia (FM).The study included 60 women with primary FM and 30 healthy individuals. Resting electrocardiography, echocardiography and exercise treadmill test were used to compare these two groups. At apical four-chamber window, samples of transmitral diastolic inflow and tissue Doppler imaging of left ventricle lateral wall were obtained. Left ventricle ejection fraction was measured via modified Simpson's method. Exercise duration, maximal exercise capacity, maximal heart rate (HR) (bpm), maximal HR (%), rate-pressure product at maximal HR (bpm × mmHg), heart rate recovery 1 (bpm), heart rate recovery 2 (bpm) and chronotropic reserve (%) values were calculated.Resting HR and QTc values were similar in both groups. Echocardiographic measurements in both groups did not reveal statistically significant difference except left ventricle end-diastolic diameter and left atrial diameter. Parameters related to diastolic function of the left ventricle did not differ significantly in both groups. Also, there was not any significant difference between the groups for E/E' ratio and chronotropic reserve. Exercise treadmill test results were statistically similar for both groups.Patients with FM presented a normal HR response to exercise and those patients had normal diastolic function similar to their healthy controls.
Treadmill
Cite
Citations (2)