Early changes in left ventricular anterior wall dynamics and coordination after coronary artery surgery.

T. W. Koh, J. R. Pepper, D. G. Gibson

Cardiac Department, Royal Brompton Hospital, London SW3, United Kingdom.

OBJECTIVE: To study how asynchronous left ventricular wall motion changes early after uncomplicated coronary artery surgery. DESIGN: A prospective study done before, and at 0.5, 1, and 3 hours after coronary artery grafting, with intraoperative transoesophageal cross sectional guided M mode echocardiograms, high fidelity left ventricular pressure, and thermodilution cardiac output measurements. The extent and velocity of left ventricular anterior wall thickening were measured, along with regional work and power production. Abnormal thickness changes during the isovolumic periods were detected, and their effect on energy transfer quantified as cycle efficiency. SETTING: Tertiary referral cardiac centre. PATIENTS: 25 patients with a history of chronic stable angina, mean (SD) age 60 (9) years with three vessel coronary artery disease, undergoing uncomplicated coronary artery bypass grafting. RESULTS: 4 patients had primary incoordination, as shown by wall thinning during isovolumic contraction and delayed onset of thickening (group A), and nine had premature thickening due to incoordination elsewhere (group B). The extent (thickening fraction 43 (12)% v 73 (19)%) and velocity (1.7 (0.4) v 2.5 (0.6) cm/s) of thickening were reduced in group A v group B (P < 0.001), as were regional stroke work (2.2 (0.8) v 3.3 (0.4) mJ/cm2) and peak power production (19 (5) v 32 (7) mW/cm2), P < 0.05. In group A, these values all increased significantly within 30 minutes of operation. In group B, the extent of wall thickening and peak power production were unaffected by surgery, though cycle efficiency and regional stroke work both improved by 30 minutes v before operation (73 (9)% v 61 (8)%, 4.5 (0.9) v 3.3 (0.4) mJ/cm2, P < 0.01). Surgery had no consistent effect on left ventricular cavity size, shortening fraction, or cardiac output in either group. CONCLUSIONS: Even in the absence of evidence of overt ischaemia, major disturbances of ventricular synchrony--both regional and generalised--are present in patients with a history of chronic stable angina requiring coronary artery bypass grafting. They regress within 30 minutes of revascularisation, suggesting that they are the direct result of coronary stenosis.

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