[Cardioresynchronizing therapy in treatment of cardiac insufficiency].

The authors analyze the effectiveness of cardioresynchronizing therapy (CRT) in patients with cardiac insufficiency (CI) and intraventricular conductivity disorder. The results of completed randomized studies (CONTAK-CD, MIRACLE-ICD, MUSTIC-AF, RD-CHF, COMPANION, PATH-CHF, PATH-CHF II, MUSTIC-SR, MIRACLE, MUSTIC-AF, CARE-HF) and their metanalysis are evaluated; drawbacks of these studies are demonstrated. CRT has been demonstrated to increase survival rate due to slowing down CI progress; total mortality falls thanks to CRT even without defibrillation function. High efficacy and safety of CRT in patients with CI and profound systolic dysfunction have been demonstrated; quality of life increases by 7.6 points and by 8 points in patients with III to IV functional class CI. At the same time, there is a need for additional investigations of CRT for adequate selection of patients and optimization of stimulation modes. It is not quite clear yet for what functional class CI CRT will be most effective, which criterion is most important for patient selection, whether biventricular stimulation has advantages over left-ventricular one, and whether it is necessary to stimulate the atriums or their detection is enough. Few studies on chronic atrial arrhythmias have been conducted, thus it is not known to which extent CRT is effective in this category of patients.

[Inotropic reactions of myocardium of patients with ischemic heart disease and rats during use of amiodarone].

AIM: To study effect of amiodarone on inotropic reactions of myocardium of patients with ischemic heart disease and rats. METHODS AND RESULTS: Excitability of rat myocardium has been found to be higher than that of myocardium of patients. Sarcoplasmic reticulum of myocardium of rats has greater functional reserve, therefore rat muscle preparations respond to extrasystolic stimuli with postextrasystolic potentiation. Perfusion with a solution containing amiodarone caused diminution of amplitude of extrasystolic response of muscular strips both from rats and patients. Amiodarone augmented ability of sarcoplasmic reticulum to accumulate Ca ions as it prevented decrease of postextrasystolic contraction of human myocardium and brought about postextrasystolic potentiation of muscular strips of rat myocardium. CONCLUSION: Amiodarone affected intracellular homeostasis of calcium ions in cardiomyocytes of both rats and patients. Amiodarone lowered myocardial excitability and facilitated ability of cardiomyocyte sarcoplasmic reticulum to accumulate calcium ions.

Metabolic alterations in rat myocardium in experimental acute atrial fibrillation.

Experimental atrial fibrillation in intact rats significantly decreased the content of catecholamines in atrial adrenergic fibers and phosphorylase activity, which attests to enhanced glycogen consumption in the heart. These changes were specific of the fibrillating myocardium and atria, but were absent in the ventricles. Induced atrial fibrillation did not modify activities of SDH and monoamine oxidase in cardiac subdivisions. It was hypothesized that increased energy requirements in the atria during myocardial fibrillation led to activation of anaerobic metabolism.

[Effect of calcium antagonists verapamil and amlodipine on the risk of development of atrial fibrillation after coronary artery bypass grafting]. / Vliianie antagonistov kal'tsiia verapamila i amlodipina na risk razvitiia fibrilliatsii predserdii u bol'nykh posle aortokoronarnogo shuntirovaniia.

AIM: To assess effect of calcium antagonists amlodipine and verapamil on the risk of development of atrial fibrillation after coronary artery bypass surgery. MATERIAL: Of 74 patients subjected to mammary artery and venous coronary bypass grafting with the use of cardiopulmonary bypass 19 received amlodipine and 21 - verapamil. RESULTS AND CONCLUSION: Attacks of atrial fibrillation during 24 hour ECG monitoring were registered in 22.9% of patients mostly on days 2 and 3 after surgery. In verapamil treated patients atrial fibrillation occurred 1.5-2 times more often than in amlodipine treated patients or in patients receiving no calcium antagonists. This could possibly be explained by pronounced slowing of atrio-ventricular conduction by verapamil at the background of postoperative general "irritation" of the atrial myocardium.

[Effect of amiodarone on the extrasystolic and post-extrasystolic contractions of the isolated myocardium of rats and of patients with chronic ischemic heart disease]. / Vliianie amiodarona na ékstrasistolicheskoe i postékstrasistolicheskoe sokrashchenie izolirovannogo miokarda krys i bol'nykh s khronicheskoi ishemicheskoi bolezn'iu serdtsa.

Peculiarities in the extrasystolic and post-extrasystolic contractility of the isolated myocardium of patients suffering from chronic ischemic heart disease (IHD), in comparison to that of intact rats, were studied in the presence of the antiarrhythmic drug amiodarone. The contractility was measured in an isometric mode at an electric stimulation frequency of 0.5 Hz, a temperature of 37 degrees C, and a perfusion rate of 10 ml/min. The extrasystolic action was produced by additional electric pulses generated 25 sec after the base stimulation signal. Amiodarone (1 microgram/ml) reduced the inotropic response of intact rat myocardium to the extrasystolic action, but increased the post-extrasystolic contractility. In the myocardium of IHD patients, the drug also suppressed manifestations of the spontaneous abnormal contractility, while not decreasing the inotropic response to the extrasystolic action. An increase in the post-extrasystolic contractility reached on the average 24% (against 6% in the control). The effect of amiodarone on the post-extrasystolic contractility can be related to a change in the functional state of sarcoplasmic reticulum (SR) and in the content of deposited Ca2+ ions. SR is an important factor of intracellular homeostasis of cardiomyocytes during IHD and can probably influence the antiarrhythmic efficacy of amidarone in IHD patients.

Effect of class III antiarrhythmic preparation nibentan on extrasystolic and post-extrasystolic contraction of rat papillary muscle.

The effect of nibentan (2.5 and 25 muM) on extrasystolic and post-extrasystolic contraction of isolated and perfused papillary muscle was studied. The muscle contracted in an isometric regimen at a rate of external electrical stimulation of 0.5 Hz in a temperature-stabilized chamber (36.0+0.5 degrees C). The extrasystolic contraction was induced with an extra electrical pulse applied 0.25 sec after the regular stimulus. Nibentan decreased the amplitude of extrasystolic contraction in a dose-dependent manner. At the same time, the effect of nibentan on extrasystolic contraction practically did not depend on its concentration. It is concluded that nibentan produces a dose-dependent effect on excitability of rat ventricular myocardium, and in parallel improves calcium-accumulating capacity of the sarcoplasmic reticulum in cardiomyocytes.

[An external cardiac pacemaker for prevention of atrial fibrillation]. / Naruzhnyi élektrokardiostimuliator dlia profilaktiki fibrilliatsii predserdii.

The paper presents an account of and the technical data of a new external pacemaker to be used to prevent atrial fibrillations. It shows it expedient to design such devices and presents their characteristics.

[Evaluation of the possibility of selection of individual anti-arrhythmia therapy]. / Otsenka vozmozhnosti individual'nogo podbora antiaritmicheskoi terapii.

Antiarrhythmic therapy was chosen for 3-7 days by modified chronic electrophysiological study at three stages: (1) the efficacy of a drug, its action onset and termination were defined; (2) a dosage was chosen on an individual basis and the duration of drug potency was specified; (3) the dosage regimen of a drug given as a course therapy was confirmed by the results of trials. Its choice was made on the basis of the oral administration of a tested drug and multiple programmed electric cardiostimulation. In late periods (3-37 months), the therapy was effective and safe in 51 (86%) of 59 patients. The drug regimens and doses were in poor agreement with conventional ones in 49% of the patients. The method proposed makes it possible to choose antiarrhythmic therapy on an individual basis and reduce the number of complications.

[Reproducibility of reciprocal atrioventricular tachycardia during intracardiac and transesophageal electric stimulation]. / Vosproizvodimost' retsiproknykh atrioventrikuliarynkh takhikardii pri vnutriserdechnoi i chrespishchevodnoi elektro-kardiostimuliatsii.

A feasibility to provoke reciprocal atrioventricular tachycardias was examined in 23 patients with atrioventricular nodal tachycardia and 17 with orthodromal tachycardia in the presence of the Wolff-Parkinson-White syndrome with endocardiac and transesophageal diagnostic pacing. Atrioventricular nodal tachycardia could be induced in all 23 (100%) patients both by endocardiac and transesophageal pacing. Orthodromal tachycardia was provoked only in 9 (53%) of 17 patients by transesophageal pacing. It was generally noted that tachycardia induction required more "aggressive" regimens of transesophageal pacing than endocardiac one. Endocardiac diagnostic pacing is now a more informative technique, but transesophageal pacing requires further development.