Efficiency evaluation of autonomic heart control by using the principal component analysis of ECG P-wave.

BACKGROUND: Cardiac output is controlled by the autonomic nervous system by changing the heart rate and/or the contractions of the heart muscle in response to the hemodynamic needs of the whole body. Malfunction of these mechanisms causes the postural orthostatic tachycardia syndrome and/or the chronic fatigue syndrome. Evaluation of functionality and efficiency of the control mechanisms could give valuable diagnostic information in the early stages of dysfunction of the heart control systems and help to monitor the healing process in rehabilitation period after interventions. OBJECTIVES: In this study we demonstrate how P-wave changes evoked by an orthostatic test could be quantitatively evaluated by using the method based on the principal component analysis. METHODS: ECG signals were recorded during an orthostatic test performed according to the typical protocol in three groups of volunteer subjects representing healthy young and older persons, part of which had transient periods of supraventricular arrhythmias. Quantitative evaluation of P-wave morphology changes was performed by means of principal component analysis-based method. RESULTS: Principal component-based estimates showed certain variety of P-wave shape during orthostatic test, what revealed a possibility to evaluate the properties of parasympathetic heart control. CONCLUSIONS: Quantitative evaluation of ECG P-wave changes evoked by an orthostatic test by using a newly developed method provides a quantitative estimate for functionality and efficiency of the heart rate control mechanisms. The method could be used in eHealth systems.

Heart tissue viability monitoring in vivo by using combined fluorescence, thermography and electrical activity measurements.

A prototype system for in vivo monitoring of the heart tissue viability by using combined measurements of fluorescence, thermography and electrical activity has been elaborated for cardiac surgery. The fluorescence imaging of nicotinamide adenine dinucleotide NAD(P)H in the blue light range (lambda=467 nm) by using UV light (lambda=347 nm) excitation was used to detect metabolic disturbances. The method of the principal component analysis was used for the processing of the fluorescence image sequences. Far infrared (lambda=7.5-13 microm) imaging was used to evaluate temperature dynamics of the tissue surface during circulation disturbances. Evaluation of the epicardial electrogram shape by using continuous wavelet transform was used to detect and evaluate ischemia-caused disturbances of the electrical activity of the tissue. The combination of temperature, fluorescence and electrical activity estimates obtained from synchronically registered parameters during the experiments on model systems and experimental animals yielded qualitatively new results for the evaluation of cardiac tissue viability and enabled to achieve a versatile evaluation of the heart tissue viability.

Characterization of the gap junction protein connexin37 in murine endothelium, respiratory epithelium, and after transfection in human HeLa cells.

Affinity-purified antibodies to oligopeptides derived from two different regions of the carboxyterminus and cytoplasmic loop or to the last 103 C-terminal amino acids of mouse connexin37 (Cx37) were used to characterize expression of this gap junctional protein in endothelium of several murine tissues. Cx37 was expressed in endothelium of large blood vessels in brain, liver, kidney, spleen, heart, and lung, but not in capillaries. In addition, weak Cx37 immuno-signals were observed in lung respiratory epithelium of small bronchi and in alveolar epithelial cells of bronchioli. The ratios of Cx37 protein to Cx37 mRNA in adult and embryonic kidney as well as skin were 29-303-fold larger than in lung, suggesting that Cx37 mRNA was translated at different efficiencies in kidney and skin versus lung. Cx37 protein was more abundant in embryonic kidney and lung than in the corresponding adult tissues. After differential centrifugation of plasma membrane fractions in sucrose gradients, we found that Cx37-containing gap junctions in lung were much smaller than Cx32 and Cx26 aggregates from liver. HeLa cells were transfected with mouse Cx37 cDNA. In these cells, mouse Cx37 protein was phosphorylated mainly at serine, less at tyrosine, and very little at threonine residues. Three conductance states were resolved at 110, 240, and 315 pS.

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.