Hemodynamic assessment during exercise after left ventricular aneurysmectomy

Left-ventricular aneurysms: from disease to repair

Myocardial infarction may be complicated by the formation of a left-ventricular aneurysm that distorts the normal elliptical geometry of the ventricle to produce a dilated spherical ventricle with limited contractile and filling capacities. One of the consequences is congestive heart failure, which may be refractory to medical therapy and require surgical treatment. Surgical methods to restore the volume and shape of the left ventricle have evolved over the years. Nevertheless, although surgery for left-ventricular aneurysms has been performed for almost 50 years, the most appropriate approach is still controversial. This review gives an overview of the postinfarction left-ventricular aneurysm, tackling issues from the disease itself to surgical and other techniques of ventricular remodeling.

Efficacy of endoventricular circular patch plasty

OBJECTIVES

We report hemodynamic and clinical results of our series of endoventricular circular patch plasty (Dor operation) and consider some advantages of this procedure for patients with ischemic cardiomyopathy.

METHODS

Between 1996 and 2001, 23 consecutive patients with left ventricular aneurysm and/ or ischemic cardiomyopathy after myocardial infarction who underwent Dor operation were included in this study. Hemodynamic and clinical results of Dor operation were analyzed periodically. Patients were divided into two groups according to the extent of asynergy, more than 60% or not, i.e., an ischemic cardiomyopathy group (ICM group) or a simple left ventricular aneurysm group (sLVA group).

RESULTS

Hospital mortality was 4.4%. Postoperative New York Heart Association functional class was improved in all survivors to class I or II. Postoperative ejection fraction (EF) increased and postoperative left ventricular (LV) volume decreased in all survivors. In both groups, early and 1 year postoperative EF increased significantly. Additionally, end-diastolic and end-systolic volumes decreased significantly in the early postoperative period. Postoperative LV volume had re-enlarged in the cases in which preoperative left ventricular end-systolic volume index was more than 90 mL/m2, though left ventricular ejection fraction was maintained or rather improved at 1 year postoperatively. The survival rates after 3 years of the operation in the sLVA and ICM groups were 85.7% and 81.3%.

CONCLUSION

Though patients with ischemic cardiomyopathy with severe LV dysfunction may benefit the most from Dor operation, postoperative LV re-dilatation may deteriorate late mortality. At operation, whether optimal LV size and shape can be reconstructed and the timing of operation are the important issues because they affect prognoses.

Left ventricular volume reduction surgery for heart failure: a physiologic perspective

BACKGROUND

Ventricular volume reduction surgery for idiopathic cardiomyopathy fails to improve cardiac output and is associated with a high incidence of recurrent heart failure. Volume reduction surgery achieved by removing akinetic or dyskinetic myocardium after myocardial infarction appears to be associated with better outcomes. The reasons for the differences in outcomes are not clear.

METHODS AND RESULTS

The hemodynamic effect of the major forms of volume reduction surgery were predicted by using a composite model of the left ventricle in which 20% of the myocardium was given properties of either weak but contracting muscle, an akinetic scar, or a dyskinetic scar (aneurysm). The end-systolic and end-diastolic pressure-volume relationships were determined numerically for each simulated operation. Any volume reduction procedure reduced chamber size, shifting end-systolic and end-diastolic pressure-volume relationships leftward. With resection of weak but contracting muscle, the leftward shift was greater for the end-diastolic than for the end-systolic pressure-volume relationship. Conversely, with resection of dyskinetic scar, the leftward shift was greater for end-systolic than for end-diastolic pressure-volume relationships. In contrast, resection of stiff scar shifted the 2 relationships equally. The effect on overall pump function was indexed by the relationship between total ventricular mechanical work and end-diastolic pressure. There was a beneficial effect on this relationship of resecting dyskinetic tissue, an equivocal effect of akinetic scar resection, and a negative effect of removing contracting myocardium.

CONCLUSIONS

The effect of volume reduction surgery on overall ventricular pumping characteristics is determined by the differential effects on end-systolic and end-diastolic properties, which in turn are determined by the material properties of the region being removed.

Systolic and diastolic function after patch reconstruction of left ventricular aneurysms

Left ventricular function after patch reconstruction for postinfarction left ventricular aneurysms is largely unknown. In this study, 16 patients with an anteroseptal-lateral left ventricular aneurysm were treated by reconstruction of the left ventricle using a Dacron patch. Coronary artery bypass grafting was performed concomitantly in 9 patients. The size of the patch used was 57% +/- 19% of the resected myocardial scar area, including the sewing cuff area to be sutured. In these patients, the ejection fraction increased significantly from 0.28 +/- 0.12 to 0.39 +/- 0.12 (p = 0.007) at rest and from 0.32 +/- 0.14 to 0.41 +/- 0.10 (p = 0.008) during exercise. The left ventricular end-diastolic pressure and left ventricular end-diastolic volume index were reduced significantly from 14 +/- 7.0 to 8 +/- 3.2 mm Hg (p = 0.032), and from 178 +/- 116 to 92 +/- 21 mL/m2 (p = 0.016). The peak filling rate was improved significantly from 1.2 +/- 0.47 to 1.8 +/- 0.6/s (p = 0.048) postoperatively. The ratio of the peak flow velocity during the atrial kick phase to the peak flow velocity in the rapid filling phase, at the level of the mitral valve, improved (p = 0.016) after operation and remained improved up to 16 to 24 months after operation. Patch reconstruction of the left ventricle resulted in the recovery of systolic and diastolic function soon after operation, which has persisted into the late postoperative period.