The effects of excision of left ventricular scars on the electrocardiogram

Left ventricular aneurysm: a review

The vast majority of left ventricular aneurysms (LVA) are secondary to coronary artery disease. The natural history of LVA is now better understood. The increasing use of noninvasive techniques has allowed earlier recognition and better appreciation of LVA genesis and pathophysiology. Improvements in surgical anesthesia and techniques have resulted in more successful LVA surgery. This article reviews the pathogenesis, natural history, and complications of LVA. Surgical indications and available treatment options in the management of patients with LVA and severe symptoms are presented. Left ventricular pseudoaneurysm (false aneurysm) will also be discussed.

ST segment elevation with ventricular aneurysm: results of encircling endocardial ventriculotomy

The ST segment elevation characteristic of ventricular aneurysm is thought to represent unmodified repolarization of the opposing wall or to arise from viable tissue at the border of the scar because of ischemia, traction or the non-uniform injury that is the architecture for ventricular tachycardia. Encircling endocardial ventriculotomy to prevent tachycardia interrupts coronary perfusion to the viable tissue bordering the scar, with noticeable loss of electrical and mechanical function. Five patients had anterior or apical aneurysms resected and encircled to treat recurrent ventricular tachycardia. ECGs were examined 49 days +/- 12 SEM post-operatively. Encircling did not eliminate their ST segment elevation. Only one patient had less ST elevation post-operatively. Thus ST elevation associated with aneurysms does not arise from viable tissue at the edge of the scar because it persists after this tissue is damaged by encircling endocardial ventriculotomy.

Electrocardiographic changes following endocardial resection for ventricular tachycardia

The ECG changes resulting from endocardial resection, with or without aneurysmectomy and coronary artery bypass grafting (CABG), are reported in 82 patients. Angiographic and surgical features and peak creatine kinase (CK) levels are correlated with ECG findings. Twenty-three of 82 patients (28%) had the following ECG changes postoperatively: decreased ST segment elevation = 3 (4%), loss of R wave amplitude = 4 (5%), increased R wave amplitude = 5 (6%), new Q wave = 4 (4%), axis shift greater than or equal to 45 degrees = 6 (7%), and new bundle branch block = 6 (7%). Five of six new cases of bundle branch block were left bundle type and resulted from resection of the inferoposterobasal and contiguous septal endocardium. ECG anterior infarction, anterior aneurysm, and anteroseptal endocardial resection were associated with a significantly lower incidence of postoperative ECG changes. Aneurysmectomy and the performance of CABG were not significantly associated with postoperative ECG changes, but more bypass grafts per patient grafted appeared in the group with postoperative ECG changes, suggesting that coronary artery disease may be more severe in that group. Peak CK did not correlate with postoperative ECG findings. We conclude that ECG changes occur infrequently after endocardial resection and that the factors responsible are not clear, although severity of coronary artery disease may be contributory. Left bundle branch block is a significant complication of inferoposterobasal resection, but complete heart block appears not to be. The diagnosis of myocardial necrosis is difficult in these patients.

The effect of left ventricular aneurysmectomy on the electrocardiogram: a study of 77 patients and review of the literature

Electrocardiograms (ECGs) were reviewed in patients undergoing left ventricular aneurysmectomy. Post-operatively, significant decreases were noted in ST segment elevation (p less than 0.001) and anterior (p less than 0.03) and inferior R wave heights (p less than 0.002). In addition, abnormal Q waves disappeared in 50% of patients. Comparison of ECG changes between survivors and patients dying of cardiac related events revealed that patients with a preoperative axis of greater than or equal to 60 degrees, postoperative leftward axis shifts and a marked decrease in ST segment elevation and/or R wave height had significantly higher mortality.

CONCLUSION

1) Left ventricular aneurysmectomy affects ventricular depolarization as evidenced by a significant loss of R wave height and changes in infarct pattern; 2) LVA affects ventricular repolarization as evidenced by a significant decrease in ST elevation; 3) the ventricular aneurysm appears to contain "viable muscle" that contributes to ventricular depolarization and remains partially depolarized during diastole; and 4) there are prognostic electrocardiographic parameters, which correlate with mortality during postoperative follow-up.

Persistent ST segment elevation in left ventricular aneurysm before and after surgery

Post-myocardial infarction aneurysms are often accompanied by persistent ST segment elevations. To determine whether or not these ST segments regress following successful surgery for left ventricular aneurysms, serial electrocardiograms were studied in 74 patients and compared to changes of heart size and NYHA Functional Class. The mean postoperative follow-up period was 18.2 months (range 3 to 52 months). The mean precordial sigma ST elevation preoperatively was 5.27 mm. and 4.71 mm. after surgery (P less than 0.025). For the highest ST segment of an individual lead, the mean values were 1.9 mm. before surgery and 1.88 mm. postoperatively (P less than 0.1). Although clinical improvement occurred in 66 (89.2 per cent) by NYHA class and x-ray evidence of improvement was seen in 46 (62.2 per cent), a degree of ST elevation remained in all cases and was less elevated in only 19 (25.7 per cent). After surgery for left ventricular aneurysm, ST segments tend to remain elevated with little apparent relation to reduction of heart size or clinical improvement.