[Possibility of the thermographic method for detection of ischemic myocardium].

Thermography (TG) is used as a contact free method for investigation of the myocardium ischemic injury. In coronary bypass surgery without artificial blood circulation it is important to know how cessation of blood supply affects the myocardium. In experiments on working heart, TG allows monitoring temperature at the desired point of the epicardium. The aim was to investigate relations between myocardial ischemia and temperature and to prove that the ischemic tissue and border zones can be determined by TG. Experiments were performed on mongrel dogs. In the areas of induced ischemia, ventricular surface thermograms (T) and electrograms (EG) were recorded. The obtained data showed that temperatures in ischemic area and border zone of myocardium were different from those in healthy myocardium. A detailed analysis of T of ischemic area showed that between ischemic and healthy myocardium a border zone is formed which is very important for arrhythmia genesis. The border zone is several millimeters wide, and its temperature is 1C higher than in healthy myocardium. The curve of the dynamics of temperature measured at all points of the ischemic zone has been created. Correlation between myocardium temperatures and characteristics of EG of ischemic zones is shown. Conclusion. The data show that TG is an appropriate method for determination of ischemic area and border zone in ventricular myocardium. TG gives a possibility to evaluate functional status of myocardium in a contact free way and may be applied for determination of ischemic damage of myocardium during cardiosurgery.

[Changes of cardiac electrophysiological parameters after destruction of epicardial nervous plexi innervating sinoatrial node].

Electrophysiological methods were used in experiments on 15 dogs for the study of topography of right atrial epicardial nerves, their connections with sinoatrial node, and possibilities of selective surgical denervation of sinoatrial node. Epicardial nerves were electro-coagulated or cryo-destructed in ventral, lateral and dorsal atrial zones near base of vena cava inferior. The following parameters were registered: heart rate, time of restoration of sinus node function, conduction through atrioventricular node, refractoriness of atria and atrioventricular node. Comparison of cardiac parameters before and after destruction of epicardial nerves showed that in lateral and ventral zones sympathetic nerves reach sinus node through lateral and ventral zones while parasympathetic -- along dorsal zone. Selective surgical destruction allows to modify sinus node function in a desired way.

Diagnosis and surgical treatment of ectopic atrial tachycardia.

Eighty-two patients with ectopic atrial tachycardia (EAT) were subjected to radical closed heart surgery (without cardiopulmonary bypass). The age of the patients ranged from 1 to 51 years. Permanent EAT was present in 19 patients, incessant EAT in 14, and paroxysmal EAT in 49 patients. Preoperative electrophysiological study included computed analysis of the P wave vector. Ectopic foci were established in the right atrium in 34 patients, in the left atrium in 11, in the interatrial septum in 32, and extracardially in 5 patients. For ablation or isolation of the foci, the cryogenic technique was used in 74 patients, cryo- and laser techniques in 4, and the laser technique alone in 1 patient. In 3 patients resection of the atrial auricles including the ectopic focus was undertaken. In 4 patients complete AV block was induced and a cardiac pacemaker implanted. After primary surgery, favourable results were obtained in 71 patients. In 11 patients recurrences were observed; 8 of these patients underwent successful repeat surgery. In 3 patients medical treatment was effective. Finally, the follow-up results have been promising-79 patients (96.4%) (including 4 patients in whom a complete AV block was created) have become arrhythmia-free. When EAT is resistant to medical treatment, closed heart ablation of the ectopic focus has proved to be safe (no mortality or morbidity) and effective. It can therefore be recommended not only for the termination of EAT but also for the prevention of dilated cardiomyopathy.