Effect of sternotomy and coronary bypass surgery on postoperative pulmonary mechanics. Comparison of internal mammary and saphenous vein bypass grafts.

Coronary artery bypass grafting (CABG) is commonly performed via a median sternotomy with a reversed saphenous vein (SV) and/or an internal mammary artery (IMA) graft. Sternotomy and IMA harvesting may adversely affect postoperative respiratory function (PFTs) as disruption of the sternun may impair chest wall stability, and the decrease in intercostal muscle blood supply after removal of the IMA may reduce the force of respiration. We compared preoperative and six- to eight-week postoperative PFTs in patients undergoing CABG. The results were independent of age, sex, number of grafts, aortic cross clamp time, duration of bypass run, and postbypass fluid gradient. It was concluded that sternotomy caused a decrease in postoperative PFTs and that IMA harvesting may be accompanied by greater impairment in PFTs than when SV grafts alone were used.

Effects of occlusion of the left anterior descending coronary artery during angioplasty on right-sided cardiac pressures and electrocardiographic changes.

Controversy persists regarding the presence and extent of right ventricular involvement with acute anterior injury. Also unclear are the incidence and significance of ST elevations in the right-sided leads in acute left anterior descending artery occlusion. Baseline and coronary occlusion hemodynamics and 15-lead electrocardiograms (addition of RV3 through RV5) were recorded in 42 patients during 32 left anterior descending and 13 right coronary artery angioplasties. The right coronary and left anterior descending artery angioplasties had similar baseline right and left ventricular hemodynamics, as well as identical right atrial to pulmonary wedge pressure ratios (0.51 right coronary vs 0.51 left anterior descending). Whereas the right coronary and left anterior descending occlusions produced similar elevations in right ventricular filling pressures, the left anterior descending occlusions produced greater elevations in left ventricular filling pressures. The right atrial to pulmonary wedge ratio increased with right coronary occlusions, but was unchanged with left anterior descending occlusions (0.79 right vs 0.46 left, p less than or equal to 0.0001). Presence of right-lead ST elevations in 10 left anterior descending occlusions did not con-note increased right ventricular filling pressures, but did suggest increased left ventricular ischemia and dysfunction. In conclusion, right ventricular dysfunction, as manifested by increased filling pressures, is seen with both right coronary and left anterior descending occlusions. Although it is the predominant abnormality in right coronary occlusions, in left anterior descending occlusions it is proportional to left ventricular dysfunction. ST elevations in a right lead with left anterior descending occlusions do not constitute a marker for increased right ventricular dysfunction.

Pericardial effusion early in acute myocardial infarction.

The incidence and significance of pericardial effusions early in acute myocardial infarction remain unclear. Using two-dimensional echocardiography, 172 patients with an acute myocardial infarction were evaluated within 72 h of presentation. Thirty patients (17%) had a pericardial effusion (29 small, 1 moderate) while 142 (83%) did not. No patient developed cardiac tamponade or required pericardiocentesis. Patients with pericardial effusions had higher peak creatine kinase as compared to patients without effusions (2036 +/- 1466 vs. 1483 +/- 1241, p less than 0.05) and a greater number of aneurysms (20% vs. 6%, p less than 0.05). In-hospital mortality was higher in the patients with pericardial effusions (10% vs. 2%, p less than 0.05). In conclusion, pericardial effusions are common in the early AMI period but are generally small and hemodynamically insignificant. They are associated with larger infarcts and greater mortality.