The authors have studied the local blood flow regulation of the heart under the influence of the stimulation of the carotid sinus nerve in segmental myocardial ischaemia. The experiments were carried out on 38 dogs. By ligating the mid-portion of the left anterior descending coronary artery, a small artificial infarction has been produced. Circulatory examinations were made after 24 hours following the coronary ligation. In 18 dogs the circulatory investigations were done during the electrical stimulation of the carotid sinus nerve while 20 dogs were used as control. The local nutritive blood flow of the heart was measured by the administration of 86 rubidium in the intact zone, in the ischaemia (necrotic) zone and at the border zone of the heart. According to the experimental data, under the influence of the carotid sinus nerve stimulation the blood flow of the intact zone does not change considerably while the necrotic and border zones increases to a great extent. Reflex redistribution of the myocardial blood flow probably plays a decisive role in the antianginal effect of carotid sinus nerve stimulation.

Animals↗

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Effect of carotid sinus nerve stimulation on coronary blood flow in myocardial ischaemia: role of the collateral vessels.

The carotid sinus nerves of dogs were electrically stimulated to reveal reflex effects exerted on the coronary blood flow both in normal and ischaemic states. Myocardia ischaemia was produced by occlusion of the left anterior descending (LAD) coronary artery. In 10 experiments the coronary sinus outflow was measured as an index of the overall coronary flow; in 30 cases the local myocardial blood flow was registered by means of the heat clearance technique. In the overall coronary flow carotid sinus nerve stimulation (CSNS) elicited coronary dilatation. After acute LAD occlusion this effect was slightly potentiated. A similar but significantly greater potentiation was observed in the local reflex vascular dilatation recorded with the aid of the thermal probes immediately after LAD occlusion when the myocardial area explored was supplied exclusively by collateral channels. 24-48 hours and 5-64 days after the coronary ligation the effect of the CSNS on the local blood flow was tested in the developing and the regenerative phases of the myocardial infarction. In both phases an enhanced reflex dilatation was found in the collateral-dependent ischaemic areas as compared to the myocardial areas supplied by the normal vessels. The results suggest that reflexly induced intrinsic redistribution of the myocardial blood flow is one of the mechanisms responsible for the therapeutical effects of the CSNS.

Animals↗

PubMedDate not supplied

The effects of bisaramil on experimental arrhythmias.

Antiarrhythmic activity of bisaramil (3-methyl,7-ethyl,9 alpha, 4'-(Cl-benzoyloxy)-3,7-diazabicyclo[3.3.1.]nonane monohydrochloride) was investigated in a variety of experimental arrhythmic models. Bisaramil at the dose range of 0.1-2 mg/kg given i.v. was able to protect against either chemically induced (chloroform, aconitine, adrenaline, ouabain) or coronary-ligation-induced arrhythmias. Bisaramil dose dependently increased fibrillation threshold both in the right auricle and in the right ventricle (ED50 approximately 0.2 mg/kg i.v.) and decreased the susceptibility of the heart to arrhythmias induced by programmed electrostimulation alone or together with local cooling of the heart. Bisaramil given orally (5-20 mg/kg) also showed antiarrhythmic activity with a medium (2-4 h) duration of the action. Therapeutic index of bisaramil was found to be 19.6 (rat); 5.0 (dog) by i.v. administration and 46.5 (rat); 15.5 (dog) by p.o. administration. This means that bisaramil may be given rather safely.

Aconitine↗

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The effect of isolated perfusion on limb circulation in peripheral arterial occlusion.

The effects of isolated limb perfusion were studied in 12 patients suffering from peripheral arterial occlusion. The hemodynamic investigations show that the vascular resistance decreases considerably during isolated limb perfusion. After administration of a vasodilator cocktail, added to the perfusion, the vascular resistance continues to decrease. Angiographic records, made before, during and after the perfusion, suggest that the calibre of the collateral vessels increases significantly and besides new collaterals can also be observed. The mechanism of the effects of isolated hyperbaric limb perfusion and its clinical value are discussed.

Adult↗

PubMedDate not supplied

The effect of atrial dilatation on reperfusion arrhythmias: development of supraventricular tachycardias on reperfusion with atrial stretching.

UNLABELLED: The study was aimed at investigating the effect of atrial dilatation on the genesis of supraventricular tachyarrhythmias following myocardial reperfusion. Experiments were carried out in 26 mongrel dogs under pentobarbital narcosis with artificial ventilation. Electrophysiological study was performed for studying the arrhythmic condition of the heart. Investigations were carried out: (i) in normal condition, (ii) during atrial stretching (balloon dilatation of the left atrium), (iii) in reperfusion following myocardial ischemia, (iv) in reperfusion combined with atrial stretching. On reperfusion the irritability of the atrium increased moderately (on atrial extrastimuli in 3 dogs non-sustained atrial tachycardia, in 7 dogs repeated atrial responses could be induced). Reperfusion with atrial stretching, however, very markedly enhanced the atrial vulnerability, and in 19 dogs atrial tachycardia appeared spontaneously. Comparison of the effect of atrial stretching to that of atrial stretching + reperfusion showed that the reperfusion significantly augmented the arrhythmia-inducing effect of atrial stretching. CLINICAL INVESTIGATIONS: Aortocoronary bypass operations were followed by development of supraventricular tachycardia in 41 out of 428 operated cases. Atrial dilatation was detected in 37 cases, mostly before the appearance of atrial tachycardia. The data seem to prove that atrial dilatation has an important part in the pathogenesis of supraventricular tachyarrhythmias following reperfusion of myocardial ischemia.

Animals↗

PubMedDate not supplied

The association of carotid artery stenosis with carotid sinus hypersensitivity. Transitory cerebral ischaemic attack provoked by carotid sinus reflex.

The association of internal carotid stenosis with the carotid sinus syndrome represents a special clinical entity. Transitory cerebral ischaemic attack (TIA) will usually be manifested by activation of carotid sinus reflex. Eighteen patients were observed suffering from both carotid sinus hypersensitivity and TIA. The patients had had TIA's for many years. Unilateral internal carotid stenosis was detected in 15 cases, while 3 patients had bilateral carotid stenosis. On carotid sinus stimulation, syncope appeared and a TIA could be provoked. The mean duration of the syncopic attack was 5500 ms and was based on sinus arrest in 14 cases and on third degree AV block in 4 cases. In all patients carotid artery disobliteration was performed; in 14 patients pacemaker implantation was necessary, while 4 patients could be treated by atropine medication. The development of a TIA could be abolished in every patient and 14 patients remained totally symptom free.

Adult↗

PubMedDate not supplied

Arteriovenous shunts associated with peripheral obliterative arterial disease. Haemodynamic, arteriographic and isotope studies.

From among 210 patients with severe peripheral obliterative arterial disease, the presence of an arteriovenous shunt was demonstrated in 17 cases. Arteriovenous communications were visualized by serial angiographic records and 99mTc macroaggregate isotope testing. The regulation of the limb circulation was investigated using the venous isotope dilution method. Characteristic haemodynamic changes were revealed in arteriovenous shunts associated with peripheral arterial obliterative disease: total limb blood was comparatively high, arteriovenous difference was low and limb O2 consumption was decreased. The clinical significance of the haemodynamic changes in arteriovenous shunting associated with obliterative arterial disease is discussed.

Adult↗