There has been controversy over whether forward blood flow during closed-chest cardiopulmonary resuscitation (CPR) is generated by a general increase in intrathoracic pressure (chest-pump theory) or by creating atrioventricular gradients that close the mitral valve and open the aortic valve during thoracic compression (cardiac pump theory). The crucial issue is the position of the mitral valve during the downstroke of chest movement. Questions remain over the actual mechanics of mitral and aortic valve function. This report describes an intraoperative cardiac arrest followed by CPR during which routinely instituted two-dimensional transoesophageal Doppler echocardiography enabled study of the motion of the valves of the left heart and the transmitral blood flow.
