[Effect of thoracotomy on the contractility parameters of the left heart ventrilce in dogs].

The influence of thoracotomy on blood pressure, heart rate as well as maximal rate of pressure rise in the left ventricle (dp/dtmax), left ventricular pressure, left ventricular end-diastolic pressure, and the parameters (see article) and (see article) was studied in anaesthetized and relaxed dogs, which were artifically respired using a Bird-Mark-8-respirator. The opening of the thorax leads to the following changes in+ the cardiovascular parameters: The mean arterial blood pressure was initially raised 9%. The heart rate increased by a few beats after the thoractomy, followed by a slow continuous drop so that a slight bradycardia was registered in the late phases of thoracotomy. The left ventricular pressure rose 8% after thoracic opening. The dp/dt values exhibited a similar rise initially (increase 17%), however fell to below the control values at a later stage so that a drop of 15% was registered by the end of the experimental period. The quotients (see article) and (see article) were slightly raised immediately following the opening of the thorax. During the remainder of the experiment the parameter (see article) underwent no appreciable changes, however, the quotient (see article) decreased up until the end of experiment. The left end-diastolic ventricular pressure dropped continually after thoracotomy.