[Left bundle of his brunch block as a manifestation of the syndrome of dromotropic insufficiency in patients with chronic heart failure].

Left bundle brunch block (LBBB) is met in approximately 20% of hospitalized patients and in 1/3 of outpatients with chronic heart failure (CHF). Abnormalites of impulse conduction in LBBB promote dyssynchronization, which represent a pathophysiological process which not only worsens ventricular function but also facilitates remodeling of the myocardium and development of CHF. As a result of dyssynchrony systolic and diastolic functions of the heart are impaired. This manifests as shortening of diastole of the left ventricle and dyssynchronous movement of interventricular septum (IVS) with a tendency to lowering of local and global ejection fraction (EF), and leads to significant metabolic and energetic consequences. Abnormal geometry and dilation of the heart in CHF promotes chaotic separation of early and late activated myocardial zones. This aggravates disturbances of conduction existing as a result of fibrosis and causes weakening of contractility and slowing of impulse conduction velocity. These morphological changes facilitate electrophysiological deviations and formation of abnormal conduction. LBBB is undoubtedly involved in development of sudden death of patients with CHF, but its effect on long term prognosis remains ambiguous and possibly the role of no small importance in this belongs to severe concomitant pathology and dysfunction of left ventricular myocardium.