Ventricular apical vents and postoperative focal contraction abnormalities in patients undergoing coronary artery bypass surgery

Effects of revascularization after first acute myocardial infarction on the evolution of QRS complex changes (the DANAMI trial). DANish Trial in Acute Myocardial Infarction

The changes in QRS complex morphology associated with acute myocardial infarction (AMI) can resolve spontaneously over time. Whether complete revascularization of the infarct-related myocardial territory after AMI affects this QRS resolution has not been studied adequately. The present study compares the evolution of the changes in the QRS complex associated with AMI during 1-year follow-up in patients treated with or without revascularization after their first thrombolyzed AMI. The study is a substudy of the DANish Trial in Acute Myocardial Infarction (DANAMI) (n = 1,008) that randomized patients with inducible ischemia after their first AMI, treated with intravenous thrombolytic therapy, to conservative treatment or coronary angiography followed by the appropriate revascularization strategy. A total of 817 patients had complete sets of evaluable electrocardiograms. Electrocardiograms were obtained at randomization, and at 3, 6, and 12 months of follow-up and subjected to blinded core-laboratory evaluation according to the Selvester QRS scoring method. This score considers Q-, R-, and S-wave duration and ratios to provide a semiquantitative estimate of AMI size. The median electrocardiographic estimated infarct size in the entire population was 15% of the left ventricle at randomization. At the end of the follow-up period this estimate had decreased to 12% (p < 0.00001). There was no difference in the rate of QRS resolution whether the patients were subgrouped according to randomization or subgrouped according to actual treatment with or without revascularization. The present study confirms the findings from previous studies conducted in the prethrombolytic era, that considerable normalization of the QRS complex also occurs after AMI treated with thrombolytic therapy. This QRS normalization seems unaffected by an aggressive treatment strategy with revascularization via balloon angioplasty or bypass surgery.

Pulmonary artery versus left ventricular venting: a radioisotope study of left ventricular function

Radionuclide measurements of ejection fraction were used to assess immediate and late postoperative ventricular function after the use of either a pulmonary artery vent (group A) or a left ventricular vent (group B) in 20 patients undergoing aortic valve replacement for pure aortic stenosis. Ten patients were included in each group and anesthetic techniques, patient management, and septal temperatures were similar in all cases. No significant difference was found between the preoperative and immediate or 6-week postoperative ejection fractions, either taken overall or between the two groups (p greater than 0.05; Student's t test). No correlation was found between cross-clamp time, bypass time, or the occurrence of ventricular fibrillation and the immediate postoperative ejection fraction (p greater than 0.05; Student's t test). There was no significant difference in the incidence of ventricular fibrillation after each type of vent had been used (chi 1(0) = 3.32; p greater than 0.05). We did not demonstrate any abnormalities in regional wall motion associated with apical insertion of a left ventricular vent, and conclude that pulmonary artery and left ventricular vents are equally satisfactory in terms of postoperative ventricular performance.

Enhancement of an old diagnostic tool, the standard 12-lead ECG

The standard 12-lead electrocardiogram (ECG) has long been a reliable clinical tool for diagnosis of myocardial infarction (MI). Minutes may be crucial in the decision regarding urgent interventions for the salvage of severely ischemic myocardium during an acute MI. Besides history and physical findings the ECG may be the only clinical tool immediately available in deciding to initiate acute coronary thrombolysis or balloon angioplasty. Most of the newer techniques are difficult to perform and time consuming, and thus are not immediately available. Recent studies have indicated that there may be important information revealed by the amplitude and direction of the ST-T vectors on the admission ECG that will correlate with the final infarct size which evolves during the next few hours. The Selvester QRS scoring system, based on computer simulations of the human heart activation sequence, uses quantitative information in the 12-lead ECG to estimate the size of an MI. This system, which can be automated, has been examined for specificity in a large database of normals, and validated in a series of comprehensive post-mortem studies, and in other clinical estimates of prognosis and MI size. The QRS scoring system is limited by its inability to differentiate between small MIs and normal myocardium and by the confounding effects on the ECG of ventricular hypertrophy, conduction defects, and multiple MIs. Current studies are expected to overcome most of these limitations. Computer technology further augments the clinical utility of the ECG by providing unique assessment of a patient from individualized demographic and historical characteristics.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative rates of resolution of QRS changes after operative and nonoperative acute myocardial infarcts

An independently developed and previously validated QRS scoring system for estimating myocardial infarct size has been used to compare the development and regression of changes associated with myocardial infarcts occurring in 2 different clinical settings. It is known that QRS changes suggesting myocardial infarction occur after coronary artery bypass grafting. This study compares the magnitudes and time courses of these QRS changes in 40 patients with the QRS changes observed in a control group of 46 patients with nonoperative acute myocardial infarcts. Only patients in both groups who had a baseline electrocardiogram (ECG) with no evidence of previous myocardial infarcts, ventricular hypertrophy, or bundle branch block were included. Both groups attained similar peak QRS scores during the acute phase but different rates of resolution of scores were observed. During the subsequent 2 months, regression of QRS changes occurred more rapidly in the perioperative group than in the control group (43 versus 19%). Rates of regression were similar in both groups during the remainder of the follow-up period, attaining total decreases of 62% in the operative group and 37% in the nonoperative group by 18 months. These results could mean either that factors other than acute infarction are responsible for the perioperative QRS changes or that the infarct healing process in the 2 clinical settings are quite different.

Unusual complications of coronary bypass surgery

Five patients after coronary bypass surgery developed unusual complications. Three developed new apical thrombi which are thought to be due to the trauma of the left ventricular vent or deterioration of the left ventricular contraction. Significant new mitral regurgitation in one patient probably is secondary to papillary muscle dysfunction as the result of stenosis distal to anastomoses. The leakage of angoigraphic material around distal anastomatic site is due to technical error. Although these unusual complications are very rare, however, they should be considered as potential source of morbidity in asymptomatic patients who leave the hospital after bypass surgery.