A total of 106 patients participated in a clinical investigation to determine the incidence and etiology of pulmonary complications following myocardial revascularization with the internal mammary artery graft; 39 patients (group I), undergoing valve replacement or myocardial revascularization with vein grafts, served as control. The mammary artery was used for revascularization in the remaining patients. The pleura was opened during the dissection of the mammary graft in 34 patients (group II), but was left intact during harvesting of the internal mammary artery in 33 patients (group III). Inspiration and expiration chest X-rays were obtained during the first 3 months of convalescence to determine the presence of pleural fluid, the position of the left hemidiaphragm, and to asses diaphragmatic movement. Pleural effusions, left lower-lobe atelectasis, and elevation of the left hemidiaphragm were observed in all groups after operation, but were more commonly observed in those patients undergoing revascularization with the mammary artery graft. Postoperative chest X-rays just prior to discharge from hospital were normal in 69% of the control group, only 9% of patients in group II who had pleurotomy during mammary artery dissection, and 42% of group III. By 3 months, however, 95% of patients in groups I and II had normal chest X-rays, whereas 53% of patients in group II had persistent loss of left-lung volume related to the presence of left-lower-lobe atelectasis, left pleural effusions and organization of the postoperative hemothorax.(ABSTRACT TRUNCATED AT 250 WORDS)

Late vein graft occlusion following myocardial revascularisation is usually the result of progressive intimal hyperplasia which ultimately leads to vein graft thrombosis. Considerable attention has recently been directed towards the development of optimal platelet-inhibiting drug regimens designed to prevent intimal hyperplasia in autogenous vein grafts. This report describes an animal model that reliably reproduces short-term intimal hyperplasia in autogenous vein grafts, thus facilitating the study of platelet-inhibiting drug regimens for the prevention of intimal hyperplasia. 28 segments of undistended jugular vein were implanted end-to-end between bilaterally divided femoral arteries in 14 mongrel dogs. Seven control animals (CON) received a non-lipid diet one week before and for 6 weeks following vein implantation. A further seven animals received a 2% cholesterol diet throughout the study. Serum cholesterol was measured at 4.06 +/- 0.6 mmol X litre-1 in the CON and did not change significantly throughout the study. Serum cholesterol rose from 3.9 +/- 0.4 to 8.5 +/- 0.8 mmol X litre-1 in the lipid-supplemented animals (p less than 0.001). Vein grafts were harvested at 6 weeks and fixed in formaldehyde. Precise measurements of intimal thickness in microns were measured from multiple vein graft cross-sections with a Zeiss computerised interactive image analysing system. A mean of 102 +/- 15 measurements were made from each vein graft cross-section. Intimal thickness of autogenous vein grafts prior to implantation were similar in both groups and measured 4.15 +/- 0.4 micron. Intimal thickness increased in CON animals to 23.3 +/- 3 microns.(ABSTRACT TRUNCATED AT 250 WORDS)

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