Hemodynamic-kinetic controlled extracorporeal circulation in heart surgery]

Mimicking the physiological characteristics of the circulatory system, pulsatile bloodflow has also been introduced into extracorporeal perfusion to avoid known postoperative complications. In a mathematical consideration of the situation bloodflow is seen as a function of time F(t) for approximately constant vessel diameter over a given time. The kinetic energy of a column of blood produced by the heart-lung machine is transmitted directly to the arterial circulation via the aorta. The nature of the energy release can give rise to both positive (organ perfusion) and negative (damage to endothelium) effects. This study investigates how this energy release can be optimised, using the following experimental approach. A Doppler flow-measuring probe is placed on the ascending aorta to monitor the extracorporeal circulation. At the same time, the blood pressure is measured and converted to a pressure-flow curve via an A/D converter. On the basis of the parameters thus obtained, the energy released by the heart-lung machine is calculated. By regulating the functional parameters of a new generation of heart-lung machines, the bloodflow can then be adapted to the physiological requirements. Within the pulse period (cycle) a 20% rise phase ending in a slightly increasing plateau is established. The energy increase within a cycle should not exceed 150 joules. To optimize the mode of functioning of the heart-lung machine, we introduced the "energy-equivalent pressure" (EEP). Adaptation of the EEP to the physiological conditions required a basic flow of 60% at a pulse rate of 60/min and a pulse duration of 35% within the pulsatile flow interval.     

Bloodless open heart surgery with atraumatic extracorporeal circulation.

With careful refinements in the pump oxygenator and a nonblood prime, bloodless open heart surgery may be performed almost routinely. In our series these measures reduced blood trauma, with a remarkable preservation of blood elements, especially platelets, and a corresponding elimination of postoperative bleeding. The mean hematocrit value decreased from 38 to 27% and recovered to 33% in the first 3 hours of postoperative diuresis. Mannitol and furosemide were rarely needed. Of 61 adult patients whp underwent open heart surgery for aortocoronary bypass or valve replacement, the last 43 had a bloodless procedure. Of the 43, 26 (60%) required no bank blood postoperatively (in the operating room or the intensive care unit). In these 26 the operative mortality was 4% (1 patient). Bloodless techniques are invaluable during periods of bank blood shortage. They avoid the dangers of hepatitis and transfusion reaction, and they may minimize the incidence of postperfusion lung syndrome as well as renal complications.     

Study of trans-placental transport of methylamphotericin B in albino rats after intravenous administration]

Transplacental penetration of amphotericin B, an methyl derivative, was studied on rats after its intravenous administration. Microbiological and radioisotopic methods were used. When the microbiological method was applied the drug was administered on days 16 to 20 or on day 20 of pregnancy in a dose of 4 mg/kg. For extraction of the antibiotic dimethylformamide was added to the substrates. The labeled antibiotic was administered in a dose of 3.3 mg/kg on days 6 to 16 and on day 20 of pregnancy. It was noted that the antibiotic accumulated in the placenta. The accumulation was more pronounced after antibiotic use in the course doses. A significant part of the antibiotic was in the placenta in the bound state. The methyl derivative amphotericin B was not detected microbiologically in the umbilical cord serum, fetal organs and amniotic fluid. Neither was it detected by extraction with ++dimethylformamide. The labeled antibiotic was neither detected in the amniotic fluid and fetal organs during the whole observation period. Therefore, the methyl derivative amphotericin B did not penetrate through the placental barrier either in the free or bound state. The direct teratogenic action of amphotericin B, a methyl derivative, after its intravenous administration to female rats is likely possible.     

Combined usage of inhaled and intravenous milrinone in pulmonary hypertension after heart valve surgery

Secondary pulmonary hypertension is a frequent condition after heart valve surgery. It may significantly complicate the perioperative management and increase patients' morbidity and mortality. The treatment has not been yet completely defined principally because of lack of the selectivity of drugs for the pulmonary vasculature. The usage of inhaled milrinone could be the possible therapeutic option. Inodilator milrinone is commonly used intravenously for patients with pulmonary hypertension and ventricular dysfunction in cardiac surgery. The decrease in systemic vascular resistance frequently necessitates concomitant use of norepinephrine. Pulmonary vasodilators might be more effective and also devoid of potentially dangerous systemic side effects if applied by inhalation, thus acting predominantly on pulmonary circulation. There are only few reports of inhaled milrinone usage in adult post cardiac surgical patients. We reported 2 patients with severe pulmonary hypertension after valve surgery. Because of desperate clinical situation, we decided to use the combination of inhaled and intravenous milrinone. Inhaled milrinone was delivered by means of pneumatic medication nebulizer dissolved with saline in final concentration of 0.5 mg/ml. The nebulizer was attached to the inspiratory limb of the ventilator circuit, just before the Y-piece. We obtained satisfactory reduction in mean pulmonary artery pressure in both patients, and they were successfully extubated and discharged. Although it is a very small sample of patients, we conclude that the combination of inhaled and intravenous milrinone could be an effective treatment of secondary pulmonary hypertension in high-risk cardiac valve surgery patient. The exact indications for inhaled milrinone usage, optimal concentrations for this route, and the beginning and duration of treatment are yet to be determined.     

Personal observations of dobutamine effectiveness after surgery with extracorporeal circulation

This report describes the use of dobutamine in patients presenting a low output syndrome after cardiosurgical operations i EEC. Of 565 patients operated on valvular heart defects and coronary artery disease in 89 patients (15.7%) a low output syndrome was diagnosed and treated. Dobutamine proved to be effective in patients with moderate impairment of the left ventricular contractility. In those with severe left ventricular dysfunction, dobutamine was ineffective and other catecholamines ought to be used. The authors support the view that combined administration of dobutamine (or other catecholamines) and nitroglycerin in patients with low output syndrome proves to be superior to the effect of each single drug.     

A patient with four artificial heart valves after ergotamine therapy

A 67-year-old female was evaluated in the out-patient clinic because of shortness of breath on exertion and regular spells of fever. She had been taking ergotamine tartrate to treat migraine for more than 30 years. The patient had undergone aortic-valve replacement for aortic insufficiency three years before. On echocardiographic evaluation, severe retraction and insufficiency of the remaining native heart valves was demonstrated. Endocarditis and carcinoid syndrome were excluded. The mitral, tricuspid and pulmonary valves were all replaced by a mechanical valvular prosthesis. Pathological-anatomical evaluation of the three replaced valves and the aortic valve replaced three years earlier disclosed identical findings, compatible with long-term ergotamine use. Nine months after surgery, a sick sinus syndrome developed necessitating implantation of a DDDR pacemaker with a right atrial and a coronary sinus lead. Functional class according to the New York Heart Association improved from class III to I. After stopping the ergotamine, the fever disappeared. However, the migraine spells reoccurred which are now being treated with paracetamol.     

An apparatus for artificial circulation in laboratory animals

An artificial circulation apparatus consisting of two membrane pneumatic adaptive diaphragmatic-type pumps and artificial film-type lungs and principle of its operation are described. The apparatus permits maintaining volume blood flow to 800 ml/min during organism resuscitation after endured clinical death including prolonged one as well.