Changes in electrocardiographic morphology reflect instantaneous changes in left ventricular volume and output in cardiac surgery patients.
We examined the relation between changes in R-to-T wave amplitude ratios (R:T) and left ventricular (LV) performance as cardiac output was rapidly varied by inferior vena caval occlusion in 6 subjects prior to cardiopulmonary bypass. To assess the influence of contractility, paired studies before and after bypass were performed in 4 subjects. Stroke volume and cardiac output were assessed by aortic flow probe, and transesophageal echocardiographic LV area measures using the automated border-detection method were used to give LV stroke area, stroke force, maximal LV area, fractional area change, end-systolic elastance, and preload recruitable stroke force. Data were collected on computer and analyzed by linear regression. Significant changes in R:T and measured LV variables during the inferior vena caval occlusion were stroke volume (r = 0.81), LV stroke area (r = 0.77), LV stroke force (r = 0.81), maximal LV area (r = 0.78), and cardiac output (r = 0.80). However, R:T varied inconsistently in relation to fractional area change. After cardiopulmonary bypass, the linear relation between R:T with LV stroke force, LV stroke volume, and maximal LV area persisted, but at a lesser slope. Although absolute pre-inferior vena caval occlusion R:T did not correlate with end-systolic elastance or preload recruitable stroke force, the change in the slope of these linear relations correlated well with the change in end-systolic elastance after surgery (r = 0.92). Instantaneous changes in electrocardiographic morphology reflect changes in LV preload-dependent variables, whereas long-term changes in electrocardiographic morphology may also reflect changes in contractile state.
Pinsky
M R
MR
Division of Critical Care Medicine, University of Pittsburgh School of Medicine, Pennsylvania, USA.
Gorcsan
J
J
Gasior
T A
TA
Mandarino
W A
WA
Deneault
L G
LG
Hattler
B G
BG
Kunig
H
H
D000368:Aged; D002302:Cardiac Output; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D003327:Coronary Disease / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D017548:Echocardiography, Transesophageal; D004562:Electrocardiography; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D013318:Stroke Volume; D016277:Ventricular Function, Left