[Clinical aspects of acute circulatory disorders in open-heart operations]

An analysis of 705 open-heart operations under extracorporeal circulation for acquired and congenital valvular defects is presented. Acute circulatory disorders (ACD) were diagnosed on the basis of combined hemodynamic, metabolic and clinical findings. The mechanisms of ACD developing at open-heart operations are always multifarious. The hemodynamic pattern is conditioned by narcosis, extracorporeal circulation, cardiac manipulations and myocardial injury, blood loss, the interference with the patient's internal environment, etc. Reduced myocardial contractility and the cardiac index diminished below 2.2 l/m2/minute are stable features associated with ACD. Characteristically, systemic peripheral resistance shows no compensatory increase in some ACD cases or is reduced significantly due to narcotic vasoplegia or allergic vascular response. Reduced venous return to the heart due to reduced vascular volume and increased vascular bed capacity is sometimes masked by reduced myocardial contractility, as manifested in an increase of diastolic heart-filling parameters (right atrial pressure, occlusion pressure), which is, however, unevenly distributed between the right and left departments of the heart, a fact not to be ignored in the diagnosis. In 70% of the cases, ACD correspond to various rhythm disorders which can be of primary importance. Dynamic patterns of various parameters (atrial blood pressure, right atrial pressure, occlusion pressure, heart rate, ECG, venous HbO2, etc.) are more important in the assessment of circulation compared to absolute values. The treatment of ACD should be combined to include the best anesthetic method, the control of myocardial contractility and volume, heart rate, vascular tone and various internal environmental parameters (pulmonary gaseous exchange, acid-base balance, electrolytic balance etc.), and also antiallergic therapy. Catecholamines are effective in particularly severe cases.