The Harmful Effects and Treatment of Coronary Air Embolism During Open-Heart Surgery

Abstract

Residual coronary air embolism after heart-lung bypass is an occasional cause of poor myocardial contractility and low cardiac output. To quantitate the amount of myocardial depression from given amounts of air and to explore the most efficient way to remove coronary air, 19 dog experiments were carried out. During extracorporeal circulation, balloons were inserted into the right and left ventricular cavities to measure isovolumetric myocardial contractility. Small amounts of air injected into the aortic root caused transient myocardial depression with rapid recovery. Repeated injections of small amounts of air produced an additive effect—more depression and slower recovery with each injection. A pure peripheral vasoconstrictor was not as effective as an inotropic drug such as ephedrine or isoproterenol in improving contractility. By far the most effective method of removing air from the coronary arteries and improving contractility and color of the myocardium was to increase the perfusion flow rate for one minute to one and one-half to two times normal. Large amounts of foam appeared from the coronary sinus when flow rates were increased, and hearts intractable to electrical defibrillation became pink and responded to a single shock.