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Enhanced regional left ventricular function after distant coronary bypass by means of improved collateral blood flow
V Dilsizian1, R O Cannon, C M Tracy
1Cardiology Branch, National Heart, Lung, and Blood Institute, Bethesda, Maryland 20892.
Insights
Coronary artery bypass surgery significantly improves left ventricular function, even in areas not directly revascularized. This enhancement in cardiac performance benefits patients with multivessel coronary artery disease.
Area of Science:
- Cardiology
- Cardiac Surgery
- Medical Imaging
Background:
- Multivessel coronary artery disease (CAD) affects left ventricular function.
- Assessing the impact of coronary artery bypass surgery (CABS) on non-directly revascularized regions is crucial.
Purpose of the Study:
- To evaluate if CABS improves left ventricular (LV) function in regions not amenable to direct revascularization.
- To assess the functional changes in posterolateral LV regions supplied by the left circumflex artery after CABS.
Main Methods:
- Studied 24 patients with multivessel CAD using radionuclide angiography and coronary arteriography pre- and post-CABS.
- Assessed LV regional function by dividing the LV into 20 sectors, focusing on 8 posterolateral sectors for left circumflex artery distribution.
- Analyzed global and regional ejection fraction changes from rest to exercise.
Main Results:
- CABS significantly increased global LV ejection fraction during exercise (43% to 50%, p<0.001).
- Improvement in LV function was observed in posterolateral segments during exercise (patent or non-patent left circumflex graft).
- Functional improvements were consistent regardless of bypass graft patency to the left circumflex artery.
Conclusions:
- Coronary artery bypass surgery enhances global and regional left ventricular function.
- The benefits extend to regions not directly revascularized, suggesting improved collateral circulation or stunning recovery.
- CABS is effective in improving cardiac function in patients with complex coronary artery disease.
Abstract:
To determine whether coronary artery bypass surgery can improve function in left ventricular regions not amenable to direct revascularization, 24 patients with multivessel coronary artery disease were studied by radionuclide angiography and coronary arteriography before and 6 months after coronary artery bypass surgery. All had proximal stenosis of the left circumflex artery or a major obtuse marginal branch. Left ventricular regional function was assessed by dividing the left ventricular region of interest into 20 sectors; the 8 sectors corresponding to the posterolateral free wall were used to assess function in the left circumflex artery distribution. Change in function in the left anterior descending territory was not analyzed because of the non-specific septal hypokinesia that develops postoperatively. For the total group, coronary artery bypass surgery significantly increased both global left ventricular ejection fraction during exercise (43 +/- 13% to 50 +/- 14%, p less than 0.001) and the change in ejection fraction from rest to exercise (-7 +/- 10% to 0 +/- 6%, p less than 0.001). Such improvement was observed in 9 of 10 patients with all stenoses bypassed, and to an equivalent degree in 9 of 10 patients in whom the left circumflex artery either could not be bypassed or the bypass graft was occluded (but bypass grafts to other coronary arteries were patent). Similarly, regional ejection fraction in posterolateral segments during exercise also increased comparably after operation in patients with a patent (from 57 +/- 18% to 70 +/- 19%, p less than 0.001) or nonpatent (from 51 +/- 14% to 68 +/- 14%, p less than 0.001) left circumflex graft.(ABSTRACT TRUNCATED AT 250 WORDS)