Cor Vasa 2002, 43(4):182-186

Hemodynamics of the beating heart in myocardial revascularization from midline sternotomy without mechanical support

Michal Semrád^*, Martin Stříteský, Jaroslav Lindner, Vladimír Vondráček, Jan Krištof, Jan Roháč, Petr Bodlák, Ivan Vaněk

II. chirurgická klinika kardiovaskulární chirurgie, Všeobecná fakultní nemocnice a 1. lékařská fakulta UK, Praha, Česká republika

Aim of study:
(1) To evaluate the hemodynamic changes that occur on altering the position of the heart and on exposure of various segments of the myocardial wall to surgical intervention. (2) To assess the changes in hemodynamic parameters depending on the technique of target artery stabilization.

Methods:
We evaluated a selected group of 20 patients in 1998 (group A, pressure stabilizer), and 20 patients in 2000 (group B, negative pressure stabilizer) with three-vessel disease documented by coronary angiography. These patients were expected to be scheduled for multiple aorto-coronary bypass to all exposed areas (anterolateral wall, lateral and posterior walls, diaphragmatic wall of the left myocardial wall). We evaluated changes in hemodynamic parameters-cardiac output (CO), cardiac index, systemic vascular resistance by means of continuous cardiac output invasive measurement using a CCOmbo™ CCO/S_vO₂ thermodilution catheter. In addition, we evaluated the parameters of conventional invasive hemodynamic monitoring-mean arterial pressure (MAP) and central venous pressure (CVP).

Results:
Group A: Compared with the preoperative value, the decrease in CI on exposure of the left anterior descending artery (LAD) and the ramus marginalis sinister (RMS) is marked (p < 0.001) and much bigger than when bypassing the right coronary artery. Group B: A significant temporary decrease in CI was seen only when bypassing RMS (p < 0.001). The decrease in CI on exposure of the LAD and the right coronary artery was non-significant. The difference between the groups, i.e., between the stabilizers used, became manifest only on exposure of left ventricular anterolateral wall segments in the target area of the LAD and RD (p < 0.001).

Conclusion:
During surgery, the patient develops a temporary decrease in CO which, if treated in the operating room, does not result in low cardiac output (LCO). If using conventional invasive monitoring such as that used during surgery with the use of extracorporeal circulation (BP, HR, and CVP), every efforts is made to maintain perfusion pressure. Pharmacologically induced normotension is maintained by increasing systemic vascular resistance and will not prevent the temporary decrease in CO. MAP is not a good marker of the current hemodynamic status. (1) When using a pressure stabilizer, temporary LCO is present on exposure of two of the three main target areas. When using negative-pressure stabilization, temporary LCO occurs on exposure of one of the three main target areas. (2) Neither of the assessed stabilization techniques improves hemodynamic parameters on exposure of the left ventricular lateral and posterior walls with the target area of the ramus posterolateralis and branch of the ramus circumflexus, which is the only technical limitation to "off-pump" revascularization.

Keywords: Off-pump revascularization; Hemodynamics; Continuous cardiac output measurement

Published: April 1, 2002  Show citation