Abstracts of Posters Presented at the International Anesthesia Research Society; 72nd Clinical and Scientific Congress; Orlando, FL; March 7-11, 1998: Cardiovascular Anesthesia
Introduction: Left ventricular (LV) rate of pressure rise (LV DP/Dt) derived from the continuous Doppler profile of mitral regurgitant jet has been proven to be a reliable  and reproducible  index of peroperative LV performance in the presence of mild to moderate mitral regurgitation (MR). This study was designed to precise the accuracy of the method in presence of severe acute MR.
Methods: The study conformed to the guiding principles of the AHA guidelines for animal research. Ten pigs (25-30 kg) were anesthetized, intubated and ventilated. Monitoring included left atrial pressure (LAP) line, LV micromanometer-tipped catheter and epicardial echocardiography. MR was gradually created by successive echo-guided sections of mitral chordae tendinae by use of endoscopic scissors inserted through LV apex. At each grade of MR, preload was manipulated by successive crystalloid transfusion and blood removal maneuvers in the aim to modify LV end-diastolic area value in a range of +/- 20%. At each step of the procedure, LAP was recorded, MR was quantificated by the mitral to aortic velocity-time integral ratio (VTImit/VTIao) , Doppler derived LV DP/Dt (Dop LV DP/Dt) was calculated according to Bargiggia et al. , and peak LV DP/Dt was derived from LV catheterism data. All measurements were made blindly off-line and averaged from three successive cardiac cycles. Values are expressed as mean +/- SD.
Results: For each subject, 2 to 3 different grades of MR were created which were each analyzed at 3 different levels of preload (78 sets of measures). At the first grade of MR and minimal level of preload, LAP was 15.0 +/- 1.3 mmHg, VTImit/VTIao was 1.04 +/- 0.09, peak LV DP/Dt was 1632 +/- 403 mmHg.sec-1 and Dop LV DP/Dt was 1760 +/- 500 mmHg.sec-1. At the last grade of MR and maximal level of preload, LAP was 32.3 +/- 5.5 mmHg, VTImit/VTIao was 1.79 +/- 0.52, peak LV DP/Dt was 1367 +/- 417 mmHg.sec-1 and Dop LV DP/Dt was 861 +/- 194 mmHg.sec (-1). The gradual drift observed between peak and Dop LV DP/Dt was correlated to LAP (p<10-4) and became clinically significant when LAP was superior to 21 mmHg (Figure 1). Dop LV DP/Dt was correctable for LAP (corr LV DP/Dt) by the following equation: corr LV DP/Dt = 0.8 Dop LV DP/Dt + 22 LAP.
Discussion: Dop LV DP/Dt underestimates peak LV DP/Dt in the presence of MR-related elevated LAP. This drift is explained by the MR-related increase of instantaneous LAP concomitantly to Dop LV DP/Dt measurement which conceptually makes the assumption that LAP is constant during early systole. In the presence of MR-related elevated LAP, Dop LV DP/Dt should then be corrected for LAP.
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