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Correction of left ventricular asynchrony by coronary artery surgery
D G Gibson1, R A Greenbaum, R B Pridie
1Harefield Hospital, Middlesex.
Insights
Coronary artery bypass grafting significantly reduces asynchronous left ventricular wall motion during ejection. This suggests preoperative wall motion asynchrony may indicate impaired coronary blood flow, highlighting the value of regional analysis in coronary artery disease.
Area of Science:
- Cardiology
- Cardiovascular Surgery
- Diagnostic Imaging
Background:
- Coronary artery disease (CAD) often leads to impaired left ventricular (LV) function.
- Regional wall motion abnormalities (RWMA) are common in CAD, but their dynamic changes after surgical revascularization require further elucidation.
- Understanding the impact of coronary artery bypass grafting (CABG) on LV wall motion timing is crucial for assessing surgical outcomes.
Purpose of the Study:
- To investigate the effect of CABG on the timing of regional LV wall motion.
- To determine if CABG alters global LV function parameters.
- To assess the relationship between preoperative wall motion asynchrony and coronary blood flow.
Main Methods:
- Contrast left ventriculograms were obtained from 27 patients before and after CABG.
- Digitized ventriculograms were analyzed frame-by-frame to assess regional wall motion timing.
- Global LV function parameters (volumes, ejection fraction, filling rates) and RWMA were quantified.
Main Results:
- Global LV function parameters showed no significant changes post-CABG.
- Preoperative delayed onset of inward wall motion during ejection (diagonal contours) resolved significantly after surgery.
- The time span of inward motion onset between different LV regions decreased significantly post-CABG (190 ms to 130 ms).
- Regional hypokinesis and abnormal motion during isovolumic periods were not consistently affected.
Conclusions:
- Successful CABG significantly reduces LV wall motion asynchrony during ejection.
- Preoperative wall motion asynchrony may directly reflect impaired coronary blood flow.
- Analysis of regional wall motion is valuable for understanding functional abnormalities in CAD.
Abstract:
To investigate the effect of coronary artery bypass grafting on the timing of regional left ventricular wall motion, contrast left ventriculograms from 27 patients were digitised frame by frame before and after operation. End diastolic and end systolic volumes, ejection fraction, and peak ejection and filling rates showed no significant change. The commonest preoperative abnormality was delayed onset of inward wall motion during ejection, which was present in 14 patients over 10% (range 5-40%) of the cavity outline, leading to a pattern of "diagonal contours". After operation this pattern had resolved completely in 12 patients and partially in two. Minor abnormalities appeared postoperatively in five but overall the mean (1SD) area affected was reduced by 5 (8)%. The time span between the onset of inward motion in different regions of the cavity also fell significantly after surgery from 190 (50) to 130 (50) ms. Regional hypokinesis (6 cases) and abnormal wall motion during isovolumic contraction (4 cases) or isovolumic relaxation (5 cases) were not consistently affected. Thus successful coronary artery surgery is without consistent effect on overall left ventricular function, overall hypokinesis, or abnormal wall motion during the isovolumic periods. It does, however, strikingly reduce the asynchrony of wall motion during ejection, suggesting that before operation this abnormality may directly reflect impaired coronary blood flow. The results emphasise the potential value of analysing regional wall motion to elucidate functional abnormalities associated with coronary artery disease.