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Fig. 5.2b. Ventriculotomy closure after aneurysmectomy and coronary bypass using flet strips.

Fig. 5.2c. Organized thrombus extracted from wall of ventricular aneurysm during repair.

supplied only by the p osterior descending artery whereas the anterolateral muscle which is supplied by both the circumflex and LAD. Eighty percent of the time, ischemic mitral regurgitation is from the posterolateral papillary muscles; 20% of the time is from the anterolateral papillary muscle. Only about 20% of patients with acute papillary muscle rupture survive more than 24 hours if treated nonsurgically. Partial rupture has a much better prognosis. It should be noted that even with appropriate surgery, only two-thirds of patients with acute papillary muscle rupture survive.

How does one decide if a mitral valve replacement is needed in ischemic mitral regurgitation? Generally it depends on the severity of the mitral regurgitation and if there is organic disease involved. Obviously if there is organic disease of the valve itself as with rheumatic fever, valve replacement is indicated. If, however, the mitral regurgitation is only moderate based on the cardiac catheterization and echocardiogram, then mitral replacement or repair may not be indicated. Severe mitral regurgitation however, i.e. grade 3 out of 3, warrants inspection of the mitral valve with either repair or replacement. The mitral valve inspection and management is done after the distal anastomoses are performed, and prior to performing the proximal anastamoses although the exact sequence is not critical. At this time, an annuloplasty ring or mitral valve replacement or other form of valve repair is done.

If ruptured chordae to the posterior leaflet are found, a quadrangular excision and annuloplasty may be done. However, because of the high mortality associated with ischemic mitral valve procedures and coronary artery bypass grafting, it is often recommended to simply do a valve replacement and coronary revascu-larization rather than attempt a repair that may not work. Therefore if doubt exists, a valve replacement should be done as a definitive operation rather than a valve repair. If doubt exists as to whether the patient needs any valve procedure done at all, i.e. if there is moderate mitral regurgitation presumably due to ischemia, then one can perform coronary bypass, then come off bypass and evaluate the patient's hemodynamics. Generally, if the cardiac output is adequate, the left atrial pressure parallels the right atrial pressure and there is no huge V-wave, then one can assume that there is not a large amount of mitral regurgitation and the patient does not need mitral valve replacement. One can also evaluate this with an echocardiogram intraoperatively via the transesophageal route. It is important to remember that combined coronary artery bypass graft and mitral valve replacement for ischemia has a higher mortality (15%), compared to combined coronary bypass with mitral valve replacement for other reasons (rheumatic heart disease or mitral prolapse from degeneration) which is in the range of 7%.

All patients with acute papillary rupture after acute myocardial infarction should have prompt Swan-Ganz catheter placement, cardiac catheterization and operation since they may decompensate acutely despite initial success with medical management. The indications for surgery with chronic papillary dysfunction from ischemia are less clear. The incompetence may fluctuate in degree. The decision on CABG alone with or without mitral valve replacement or repair depends on the degree of regurgitation as noted above. Again, in general, mitral valve repair should be avoided in acute severe mitral regurgitation, or if the anterior leaflet of the mitral valve is involved. It is important to remember that mitral regurgitation from ischemia may be due to annular dilation from the left ventricular failure in addition to ischemic papillary muscle dysfunction. A rule of thumb is that in patients with angina with mild to moderate mitral regurgitation and normal left ventricular ejection fraction, CABG alone is adequate. For angina with intermittent mild to moderate mitral regurgitation occurring only with ischemic attacks, coronary artery bypass grafting alone is surely adequate. In patients with severe mitral regurgitation with good left ventricular ejection fraction, a coronary artery bypass graft with mitral valve replacement or repair is indicated. In patients

Fig. 5.3a. Anterior postinfarction VSD repaired by excising in-farcted, aneurysmal tissue, performing a Dacron patch repair of the VSD, and felt strip closure of the ventriculotomy.

Fig. 5.3a. Anterior postinfarction VSD repaired by excising in-farcted, aneurysmal tissue, performing a Dacron patch repair of the VSD, and felt strip closure of the ventriculotomy.

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