No abstract

The measurement of ventricular volume enhances the ability to appraise ventricular performance. The development of the thermodilutdon method for estimating stroke volume (SV), end systolic volume (ESV), and end diastolic volume (EDV) allowed us to reexamine myocardial function at progressive degrees of ischemic injury produced by repeated embolizations of the coronary artery. We determined left ventricular SV, ESV, and EDV together with intraventricular pressures after embolizations by lycopodium spores injected into a branch of the left coronary artery. MethodsFifteen mongrel dogs (16 to 58 kg) were anesthetized with a mixture of 70 mgAg of chloralose and 350 mg/kg of urethane and were ventilated with a pump respirator. A 7F Sones catheter, introduced from the left common carotid artery, was placed under fluoroscopic control in the origin of the circumflex branch of the left coronary artery. The tip of the catheter lay 3 to 5 cm from the coronary ostium. Identical intracoronary and central aortic pressures provided assurance that the catheter did not occlude the vessel.tion of transient, marked T wave changes in the ECG by an injection of several milliliters of cool saline, and after the experiment by autopsy. A 4F catheter, with a rapidly responding bead thermistor embedded in its tip, was introduced through a femoral artery and positioned just above the aortic valve to obtain aortic thermodilution curves. An 8F catheter, with multiple side holes and a closed end passed from the other femoral artery into the left ventricle, was used to inject thermal indicator and to measure left ventricular (LV) pressure. Another thermistor bead secured within the lumen at the tip of this catheter recorded the temperature of the injectate as it left the catheter to enter the ventricle. Injections of a measured volume (usually about 3 ml) of cooled autologous blood were made with a compressed-air device triggered by the ECG through a time-delay circuit to permit injection generally within one diastole.The end systolic volume to end diastolic volume ratio (ESV/EDV), i.e., the fraction of the maximum ventricular volume remaining after systole, was calculated from the equation:where AT tt+1 and AT, are the differences between initial aortic temperature and that of beats T n+1 and T n recorded at end diastole on the stepfunction aortic thermodilution curve.Left ventricular stroke volume (SV) and end diastolic volume (EDV) were also calculated from the aortic thermodilution curve in the manner previously described. 1 In four experiments, SV was determined by the indicator dilution method using indocyanine green injected into the left ventricle and arterial dilution curves recorded from the brachial artery through a Gilford densitometer. End systolic volume (ESV) was calculated as the difference between EDV and SV.Thermodilution curves and intraventricular pressure were recorded during a control period and again after each embolization with lycopodium spores (30 to 40 /i diameter). Embolization was accomplished with a constant dose o...

We measured the end-diastolic volume (EDV) and stroke volume (SV) in the right ventricle of anesthetized dogs during continuous pressure breathing and compared them to measurements taken during breathing at atmospheric pressure. During intratracheal positive-pressure breathing, EDV, and SV decreased and end-diastolic pressure became more positive relative to atmospheric pressure. During intratracheal negative-pressure breathing, EDV enlarged and SV tended to increase; end-diastolic pressure became more negative. During extrathoracic negative-pressure breathing SV decreased, EDV fell, though not significantly, and end-diastolic pressure rose, but insignificantly. Changes in EDV observed during intratracheal positive-pressure breathing and intratracheal negative-pressure breathing were associated with minor shifts in transmural pressure (end-diastolic pressure minus intrapleural pressure) in the expected directions, but during extrathoracic negative-pressure breathing a large increase in transmural pressure took place with the nonsignificant reduction in EDV. We believe that intrathoracic pressure influences right ventricular filling by changing the peripheral-to-central venous pressure gradient. The cause of the alteration in diastolic ventricular distensibility demonstrated during extra-thoracic negative-pressure breathing remains unexplained. positive-pressure breathing; negative-pressure breathing; extrathoracic negative-pressure breathing Submitted on August 16, 1966