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PubMed2004

Effect of hormonal replacement therapy on autonomic regulation of the heart.

BACKGROUND: Increased incidence of cardiovascular diseases frequently reported in postmenopausal women may follow disturbed activity of cardiac autonomic nervous system (cANS). Our purpose was to evaluate the influence of continuous combined hormonal replacement therapy (ccHRT) on cANS reflected by parameters of heart rate variability (HRV). METHOD: Thirty four healthy postmenopausal women aged 56+/-6 years (7+/-4 years after last menorrhoea) were divided into 2 equal groups--women receiving ccHRT (serum estradiol--81+/-75 ng/l, FSH--45+/-27 IU/l) and control group (serum estradiol--31+/-45 ng/l, FSH--74+/-32 IU/l). The ccHRT women have been receiving daily 50 mg of 17beta-estradiol (Oesclim 50, Fournier) in transcutaneous depot and 5 mg of oral progesterone (Duphaston, Solway Pharma) for recent 1.4+/-0.6 years. All recordings began at 8.00 a.m. and were carried out in supine position and resting conditions (room temperature 24 degrees C). The protocol applied consisted of 5 min. of resting ECG recording, 5 min. of deep breathing (DB) test, 6 min of sham feeding (SF) and 5 min. of ECG recording after SF. RESULTS: Analysis of the resting HRV didn't reveal any significant differences between the compared groups. In the control group during DB increases of mean LF (455+/-500 vs. 1381+/-1540; p<0.001) and LF/HF (1.5+/-1.1 vs. 5.4+/-4.3; p=0.002) ratio were observed. No influence of SF on HRV was noticed in this group. In the ccHRT women significant increases of mean LF (189+/-125 vs. 728+/-929; p=0.02) and LF/HF ratio (3.1+/-4.8 vs. 9+/-7.3; p=0.002) were observed during DB. SF revealed significant increases of mean RR (841+/-92 vs. 918+/-82; p<0.001), SDNN (35+/-14 vs. 43+/-20; p=0.02), LF (189+/-125 vs. 372+/-434; p=0.03) and HF (150+/-133 vs. 300+/-332; p=0.01). CONCLUSIONS: Our results revealed increased reactivity of the HRV parameters to vagal stimulation by DB and SF in the postmenopausal women receiving ccHRT that suggests increased activity of cANS in the analysed group. Application of ccHRT restores the premenopausal reactivity of cANS.

Aged↗
PubMed1984

Effects of atropine on atrial refractoriness and its dispersion in humans.

To evaluate the influence of atropine on atrial refractoriness and its dispersion, we studied ten subjects with sinus bradycardia who were otherwise healthy. Effective and functional refractory periods were measured at three sites of the right atrium (high, middle, and low in the lateral wall), in sinus rhythm and during atrial pacing (120/min), before and after i.v. administration of 0.04 mg/kg of atropine. Both before and after administration, dispersion of atrial refractoriness was determined from the range of refractory periods measured at the three atrial sites as the longest minus the shortest refractory period. Our data indicate that atropine was able to significantly reduce refractoriness and its dispersion. The study protocol allowed us to exclude the possibility that cycle length played a role. The antivagal effect of atropine seemed to explain our findings, even if the possibility that the drug had a direct effect could not be excluded.

Aged↗
PubMedDate not supplied

[The influence of frequency and blockade of the autonomic nervous system on the functional behaviour of the human conduction system. Part A: Conduction velocity (author's transl)].

32 patients were studied by His-bundle recordings to examine the extent to which frequency and autonomic nervous system influence the conduction velocity in the subdivisions (atrium, AV-node, His-Purkinje system) of the normal PR-interval. The measurements were performed during sinus rhythm and three electrically induced atrial frequencies before and after intravenous administration of 1 mg Atropine (15 patients) and 0.4 mg Visken (17 patients). In influencing the atrial conduction velocity frequency dominates the blockade of both components of the autonomic nervous system. Increase in frequency lengthens the intraatrial conduction time. Blockade of parasympathicus and sympathicus does not significantly influence the changes in intraatrial conduction velocity induced by increase of frequency. Patients with prolonged intraatrial conduction respond in the same way to cycle length shortening and blockade of the autonomic tone as patients with normal conduction. The results are discussed with respect to acetylcholine and catecholamine influence on the electrophysiological properties of the atrial myocardium. The AV-node is the part of the conduction system most sensitive to the influence of both cycle length shortening and blockade of the autonomic nervous system. Artificially induced cycle length shortening prolongs the intranodal conduction time to a different individual level for each patient. Blockade of the parasympathicus not only shortens this interval but also reduces the steepness of the AH-time induced by atrial pacing. Blockade of the sympathicus has the opposite effect. The most likely explanation for these results is the abolishing of the functional dissociation within the AV-node by blocking the autonomic influence on this structure. The conduction velocity in the His-Purkinje system is influenced neither by atrial pacing nor by blockade of both components of the autonomic nervous system.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Relationship between cardiac autonomic neuropathy and diabetic microangiopathies and macroangiopathy in patients with non-insulin-dependent diabetes mellitus.

The relationship between cardiac autonomic neuropathy and diabetic microangiopathies and macroangiopathy was investigated in 103 patients with non-insulin-dependent diabetes mellitus. Cardiac autonomic nerve function was assessed by determining the uptake of [123I]metaiodobenzyl-guanidine into the myocardium. Cardioparasympathetic nerve function was assessed by comparing electrocardiographically the expiratory and inspiratory respiratory rate (RR) interval ratios, during a period of deep breathing, and the coefficients of variation of the RR intervals. Nerve conduction velocity measurements were used to assess diabetic somatic neuropathy, and measurement of pulse-wave velocity provided an indication of the extent of aortic sclerosis. The only correlations between the parameters of cardiac autonomic neuropathy and parameters of diabetic microangiopathies and macroangiopathy were between the expiratory to inspiratory RR interval ratio and both the conduction velocity of the tibial nerve and pulse-wave velocity, and between the heart to lung ratio (cardiac autonomic nerve function) and nephropathy. These correlations may have occurred by chance; alternatively they may indicate a difference in the onset mechanisms of cardiac parasympathetic and sympathetic neuropathies in diabetics.

Aged↗
PubMed2005

Electroanatomical mapping and radiofrequency catheter ablation of atrial tachycardia originating from the recipient heart with recipient-to-donor atrio-atrial conduction after orthotopic heart transplantation.

Atrial tachycardias resulting from recipient-to-donor atrio-atrial conduction after orthotopic heart transplantation are difficult to treat. We present two patients in whom atrial tachycardia originating in the recipient heart were successfully treated by radiofrequency ablation guided by electroanatomical CARTO mapping system. These cases illustrate that such atrial tachycardia are curable by radiofrequency ablation. Electroanatomical CARTO mapping is useful in identifying the site of origin of the tachycardia and the atrio-atrial conduction sites.

Aged↗
PubMed1975

Electrophysiology of atropine.

The effect of atropine on the refractory periods of the human atrium, A-V node, and His-Purkinje system was studied. The A-V node in man appears more sensitive to atropine than the atria as evidenced by a reduction in the effective and functional refractory periods of the A-V node without alteration of atrial conduction. Although atropine does not directly alter the refractory periods of the His-Purkinje system, atropine-induced facilitation of A-V nodal conduction results in block of premature atrial impulses in the His-Purkinje system, demonstrating an indirect effect of atropine on His-Purkinje conduction. Rarely, atropine may precipitate re-entrant atrial tachycardia (one patient) through facilitation of A-V nodal conduction.

Adult↗
PubMed2004

Cardiovascular status in long-term survivors of Hodgkin's disease treated with chest radiotherapy.

PURPOSE: Cardiovascular status was assessed in 48 Hodgkin's disease (HD) survivors at a median of 14.3 years (range, 5.9 to 27.5 years) after diagnosis because they may be at increased risk for cardiovascular abnormalities. PATIENTS AND METHODS: Patients completed the Short-Form 36 quality-of-life instrument and were screened by echocardiography, exercise stress testing, and resting and 24-hour ECG. RESULTS: All patients received mediastinal irradiation (median, 40.0 Gy; range, 27.0 to 51.7 Gy) at a median age of 16.5 years (range, 6.4 to 25.0 years). Four patients received an anthracycline. Although every patient described their health as good or better, and none had symptomatic heart disease at screening, all but one had cardiac abnormalities on screening. Restrictive cardiomyopathy was suggested by reduced average left ventricular (LV) dimension (P < .001) and mass (P < .001), without increased LV wall thickness. Significant valvular defects were present in 42%; 75% had conduction defects. One survivor developed complete heart block shortly after the study visit. Autonomic dysfunction was suggested by a monotonous heart rate in 57%, persistent tachycardia in 31%, and blunted hemodynamic responses to exercise in 27%. Peak oxygen uptake (VO2max) during exercise, a predictor of mortality in heart failure, was significantly reduced (< 20 mL/kg/m2) in 30% of survivors. VO2max was correlated with increasing fatigue, increasing shortness of breath (both, r = -0.35; P =. 02), and decreasing physical component score on the SF-36 (r = 0.554; P = .00017). CONCLUSION: A variety of unsuspected, clinically significant cardiovascular abnormalities are common in long-term survivors of HD who are treated at a young age with mediastinal irradiation. We recommend serial, comprehensive cardiac screening of HD survivors who fit this profile.

Adolescent↗
PubMed1988

Cocaine-induced supersensitivity and arrhythmogenesis.

The mechanism of cocaine-related sudden death is unknown. To test whether cocaine potentiated changes in sinus cycle length, conduction in the atrioventricular node (AH interval) and ventricular effective refractory period induced by infused norepinephrine and ansae subclaviae stimulation, the dose-response curves of sinus cycle length, AH interval and ventricular effective refractory period to infused norepinephrine (0.01 to 0.20 micrograms/kg body weight per min) and the frequency-response curves to ansae subclaviae stimulation (1 to 4 Hz, 2 to 3 mA, 4 ms pulses) were determined before and after intravenous injection of cocaine (5 mg/kg) in 15 anesthetized open chest dogs. Cocaine potentiated shortening of sinus cycle length, AH interval and ventricular effective refractory period induced by norepinephrine infusion and shifted dose-response curves of these variables to the left in eight dogs (supersensitivity). Cocaine did not affect frequency-response curves of sinus cycle length and AH interval to ansae subclaviae stimulation. Ansae subclaviae stimulation shortened the ventricular effective refractory period more after cocaine injection, but frequency-response curves were not shifted to the left in seven dogs (no supersensitivity). Cocaine did not enhance electrical induction of ventricular tachyarrhythmias in 15 dogs without acute myocardial infarction. Acute myocardial infarction was produced by coronary artery ligation in another group of 21 dogs. Of 10 dogs with acute myocardial infarction, spontaneous or electrically induced ventricular tachycardia developed in 1 dog without drugs, in 3 dogs given norepinephrine and in 7 dogs given norepinephrine and cocaine (p less than 0.03 versus without drugs).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Experience with the organization of a pathological anatomy laboratory in a heart surgery center].

Some specific features should be taken into consideration when organizing the laboratory of pathology in the cardiosurgical centre: 1) the heart should be opened according to the modified van Pragh method; 2) heart fixation in the Brodie's liquid allowing to retain its almost natural colour, consistency, volume and shape; 3) coronary arteries filling with lead carbonate and gelatin; 4) combination of methods of both pathology and surgical anatomy; 5) investigation of the brain in the vacuum in all clinical cases of the brain coma for the diagnosis of brain artery air embolism; 6) anatomical examination of the heart conductive system; 7) formation of the automatized pathology archives; 8) transmission electron microscopy of the intraoperative heart biopsies; 9) a new method of a quantitative assessment of the lung hypertension by the investigation of lung biopsies in patients with congenital heart malformation to make a conclusion on the feasibility of operation; 10) macroscopical heart analysis at the first stage of morphological investigation.

Biopsy↗