Mechanisms of hemodynamic changes during off-pump coronary artery bypass surgery

Abstract

P Pu ur rp po os se e: : To describe the mechanisms of hemodynamic changes during off-pump coronary artery bypass graft surgery (OP-CABG).S So ou ur rc ce e: : Pertinent medical literature in the English and French languages was identified through a Medline computerized literature search and a manual search of selected articles, using off-pump coronary artery surgery, beating heart surgery, hemodynamic, and transesophageal echocardiography as key words. Human and animal studies were included. P Pr ri in nc ci ip pa al l f fi in nd di in ng g: : Hemodynamic variations in OP-CABG may be due to mobilization and stabilization of the heart, or myocardial ischemia occurring during coronary occlusion. Suction type and compression type stabilizers produce hemodynamic effects through different mechanisms. Heart dislocation (90° anterior displacement) and compression of the right ventricle to a greater extent than the left ventricle are responsible for hemodynamic alterations when using suction type stabilizers. Compression of the left ventricular outflow tract and abnormal diastolic expansion secondary to direct deformation of the left ventricular geometry are proposed mechanisms for hemodynamic derangements with compression type stabilizer. Coronary occlusion during the anastomosis can have additional effects on left ventricular function, depending on the status of collateral flow. The value and limitations of electrocardiographic (ECG), hemodynamic and echocardiographic monitoring modalities during OP-CABG are reviewed.C Co on nc cl lu us si io on ns s: : In summary, hemodynamic changes which can either be secondary to the stabilization technique or to transient ischemia represent an important diagnostic challenge during offbypass procedures. The mechanism can vary according to the stabilization system. Current monitoring such as ECG and hemodynamic monitoring are used but remain limited in establishing the cause of hemodynamic instability. Transesophageal echocardiography is used in selected patients to diagnose the etiology of hemodynamic instability and can direct therapy, particularly in those with severe myocardial systolic and diastolic dysfunction, mild to moderate mitral regurgitation, or for patients who are unstable during the procedure. Objectif : Décrire les mécanismes de changements hémodynamiques pendant le pontage aortocoronarien (PAC-CB). Source : La documentation pertinente en anglais et en français a été

Abdominal Compartment Syndrome during Off-pump Coronary Artery Bypass: a Case Report

“…Hemodynamic deterioration during OP-CABG can be secondary to myocardial ischemia, reduced preload, myocardial dysfunction, compression of cardiac chambers, mitral regurgitation, or a combination of these [7]. Because our patient showed an abrupt increase in pulmonary arterial pressure and CVP and there was no ischemic ST-T change on the electrocardiogram or mitral regurgitation during the perioperative period, the possible cause was myocardial dysfunction or compression of the cardiac chambers.…”

The degree of newly emerging mitral regurgitation during off-pump coronary artery bypass is predicted by preoperative left ventricular function

“…Factors causing deterioration in hemodynamics during OPCAB include myocardial ischemia, cardiac chamber compression, reduced ventricular fi lling, and reduced diastolic function [2,13]. In patients with impaired LV function, it is diffi cult to optimize the hemodynamic status because multiple factors tend to be involved in the deterioration of hemodynamics.…”

Esophageal Doppler and thermodilution are not interchangeable for determination of cardiac output

“…However, this is based upon physiological distribution of total CO, which is presumably disturbed under hemodynamic stress such as heart manipulation, myocardial ischemia, low CO and systemic hypotension. These conditions being fairly common during OPCAB surgery, 16 we hypothesized that upper body blood flow is probably higher than 30% of total CO during a significant part of the surgical intervention. This would be due to compensatory redistribution of CO towards the brain and the heart.…”