Time-course of medial and intimal thickening in pig venous arterial grafts: relationship to endothelial injury and cholesterol accumulation

With use of an established model of pig saphenous vein grafts in the carotid artery, the time-course of the following changes was related: (1) medial and intimal size by morphometry of transverse sections, (2) cell number by deoxyribonucleic acid concentration, (3) cell density by deoxyribonucleic acid concentration per milligram wet weight and by counting nuclei in transverse sections, (4) endothelial morphology by scanning electron microscopy, and (5) cholesterol concentration. In the first week after grafting, medial and intimal thickening occurred associated with an increase in cell number. Between 1 and 4 weeks after grafting, further rapid medial and intimal thickening occurred with no further increase in cell number but with a reduction in cell density, which suggested that cell migration, hypertrophy, and the laying down of extracellular matrix were responsible. Between 4 and 39 weeks after grafting, a slower increase in medial and intimal size occurred, associated with a parallel increase in cell number and no further change in cell density. The endothelium of grafts showed only localized abnormalities, including loss of cells and leukocyte adhesion, either 1 or 4 weeks after grafting. Cholesterol concentration was slightly elevated 1 week after grafting but returned to values similar to those in vein by 4 weeks after grafting. Distention to 600 mm Hg during surgical preparation of vein for grafting resulted in lower graft patency after either 1 or 4 weeks and caused significant medial and endothelial injury. Distention did not, however, affect changes in medial or intimal size, deoxyribonucleic acid, or cholesterol concentration caused by grafting. We conclude that three processes contribute to medial and intimal thickening, namely: (1) an initial phase of rapid smooth muscle cell proliferation, (2) smooth muscle cell migration, hypertrophy, and synthesis of extracellular matrix, and (3) a late phase of slower smooth muscle cell proliferation. The incomplete late suppression of smooth muscle cell proliferation occurs despite regeneration of a morphologically intact endothelium and in the absence of progressive cholesterol accumulation.

A surgical technique that preserves human saphenous vein functional integrity

We investigated the effect of a novel surgical preparative technique for human saphenous vein by using the concentration of adenosine triphosphate and the adenosine triphosphate/diphosphate ratio to quantify medial integrity and by using stimulated rates of prostacyclin production to quantify endothelial function. Freshly isolated vein had an adenosine triphosphate concentration of 358 +/- 54 nmol.g-1 wet weight and an adenosine triphosphate/diphosphate ratio of 2.89 +/- 0.13 (n = 12); it produced prostacyclin in response to fluid shear at a rate of 14.3 +/- 2.0 pg.min-1.mg-1 wet weight (n = 12). Surgically prepared vein obtained on completion of the last proximal anastomosis had been distended with the patient's own arterial pressure using a side-arm connected to the aortic cannula. This vein had an adenosine triphosphate concentration of 413 +/- 70 nmol.g-1 wet weight and an adenosine triphosphate/diphosphate ratio of 2.74 +/- 0.44 (n = 11), and it produced prostacyclin at a rate of 13.1 +/- 0.2 pg.min-1.mg-1 wet weight (n = 12). All values were indistinguishable from those in freshly isolated vein. The results demonstrate that this simple technique for distention at arterial pressure preserved medial and endothelial function.

A simple method of scapular retraction for posterolateral thoracotomy

A simple method of scapular retraction for posterolateral thoracotomy is presented. This technique allows for retraction and stabilisation of the scapula and prevents it from protruding over the intercostal space chosen for entry into the chest cavity. It also facilitates insertion of the chest retractor and spreading of the intercostal space since reduced tension is now exerted on the rib cage by the retracted scapula and muscle layers.

Intimal proliferation in an organ culture of human saphenous vein

This study investigated whether intimal proliferation, the characteristic feature of the response of human saphenous vein to arterial implantation, also occurs in organ culture. Vein segments were maintained for 14 days in medium supplemented with 30% fetal bovine serum. Tissue viability (measured by adenosine triphosphate [ATP] concentration) decreased only 20% from 280 +/- 20 to 220 +/- 20 nmol/g wet weight. In veins prepared for culturing, endothelial loss (approximately 20%) was confined to near the cut edges. Cultured veins retained an endothelial layer in the initially undamaged areas, while the initially injured areas became covered by a mixture of endothelial and vascular smooth muscle cells. Autoradiography in conjunction with scanning electron microscopy showed the presence of proliferating cells on the intimal surface. Transverse sections of cultured veins showed the development of a new intima containing vascular smooth muscle cells identified by immunocytochemistry with anti-alpha-actin. There were also endothelial cells identified with Ulex europaeus lectin arranged in capillarylike structures. Pulse or continuous labeling of cultures with [3H]thymidine showed that proliferating cells were confined to the new intima and suggested that the smooth muscle cells in this layer arose from both immigration and proliferation. The results demonstrate that intimal proliferation occurs in organ culture of human saphenous veins.

Wound infection following early repeat sternotomy for postoperative bleeding. An experience utilizing intraoperative irrigation with povidone iodine

A prospective observational study of median sternotomy wound infection was carried out in two consecutive groups of unselected patients undergoing early repeat sternotomy for postoperative haemorrhage. In Group A the pericardial cavity and sternotomy wound layers were irrigated with aqueous povidone iodine prior to repeat closure, while Group B did not receive povidone iodine. No median sternotomy infections were recorded in Group A compared to 5 cases in Group B (0 out of 22 vs 5 out of 21 patients, p less than 0.05). Amongst the patients with wound infection, three developed sternal dehiscence and mediastinitis with one death. The data suggests that povidone iodine irrigation may be effective in reducing wound infection in patients undergoing early repeat sternotomy after cardiac surgery.

Distention promotes platelet and leukocyte adhesion and reduces short-term patency in pig arteriovenous bypass grafts

A pig model of autologous saphenous vein to common carotid artery bypass grafting was developed. An end-to-end anastomotic technique led to lower middle graft and distal turbulence. Saphenous veins were surgically prepared with or without distention at 600 mm Hg, implanted into the arterial circulation, and removed 2 hours later. Medial integrity was then assessed by adenosine triphosphate/adenosine diphosphate concentration ratio, and endothelial integrity, leukocyte and platelet adhesion by scanning electron microscopy. In grafts made with undistended vein adenosine triphosphate/adenosine diphosphate concentration ratio was not significantly lower (3.0 +/- 0.1, n = 32) than in freshly isolated vein (3.3 +/- 0.1, n = 26), endothelial cover was 98% +/- 1%, n = 6, and there was little platelet or leukocyte adhesion. In distended grafts adenosine triphosphate/adenosine diphosphate concentration ratio was reduced to 2.2 +/- 0.2 (n = 7, p less than 0.005), endothelial cover was reduced to 38% +/- 14% (n = 6, p less than 0.001), and there was extensive platelet and leukocyte adhesion to exposed subendothelium. In separate experiments graft patency measured at 1 to 5 weeks was significantly greater (96%, n = 25) when undistended vein was used than when distended vein was used (64%, n = 25, p less than 0.005). The data show that distention leads to medial and endothelial damage and that this is associated with increased platelet and leukocyte adhesion and with reduced early patency.

Saccular oesophageal diverticulum at the site of enucleation of a leiomyoma

A case of saccular diverticulum of the oesophagus occurring at the site of enucleation of an oesophageal leiomyoma is presented. Implication for surgical therapy are discussed.

Surgical preparation impairs release of endothelium-derived relaxing factor from human saphenous vein

Release of endothelium-derived relaxing factor was measured from freshly isolated human saphenous vein and from vein subject to routine surgical preparation for coronary artery bypass grafting. Surgical preparation led to a significant decline in endothelium-derived relaxing factor release as compared with freshly isolated vein, and these changes were associated with loss of endothelial coverage. Storage of freshly isolated vein in blood but not in Hartmann's solution also resulted in a decline in maximally stimulated endothelium-derived relaxing factor release that was not associated with loss of endothelium. Reduced production of endothelium-derived relaxing factor, a potent vasodilator and inhibitor of platelet adhesion and aggregation, may be implicated in the etiology of early vein graft thrombosis.

Coronary artery bypass surgery: current practice in the United Kingdom

A survey of current clinical practice was carried out among the 84 consultant cardiac surgeons currently performing coronary artery bypass surgery in the United Kingdom. The 80 surgeons who returned the questionnaire performed an estimated total of 17,100 coronary artery bypass graft operations in 1987, a mean case load of 214 operations each. Sixty two of the 80 surgeons regarded the internal mammary artery as the graft conduit of choice, and seven preferred the saphenous vein. The internal mammary artery was used in 73% of bypass grafts to the left anterior descending coronary artery but in only 4% of grafts to the circumflex and right coronary systems. Contraindications to the use of the internal mammary artery included advanced age of the patient (51 surgeons), insufficient flow through the internal mammary artery (49), and endarterectomy (35). Seventy four of the 80 surgeons considered intraoperative damage to the saphenous vein to be a possible cause of vein graft failure, but there was no agreement about how it should be reduced. All surgeons advocated pharmacological measures to enhance graft patency. Dipyridamole and aspirin constituted the most popular regimen (58 surgeons), though only 28 started dipyridamole preoperatively. Warfarin was prescribed postoperatively on occasion by 22 surgeons, but 14 of these used it only after endarterectomy.

Late postoperative cardiac tamponade presenting as dysphagia

A case of late cardiac tamponade seen with progressive dysphagia 15 days after aortic valve replacement is reported. The diagnosis was confirmed echocardiographically and successful pericardiocentesis was followed by immediate alleviation of the dysphagia.

Traumatic rupture of the thoracic aorta

Traumatic rupture of the thoracic aorta is a lethal injury associated with high speed accidents. In multiply injured patients a high index of suspicion is required to allow prompt diagnosis of this condition. Urgent surgery is life saving in the majority of patients.

Unilateral digital ischaemia secondary to embolisation from subclavian atheroma

Four cases of unilateral digital ischaemia in the upper limb secondary to embolisation from atheromatous plaques in the proximal subclavian artery are presented. Digital subtraction angiography or arch aortography were used to demonstrate the site of atheroma. In one case diagnostic delay resulted from failure to visualise the site of embolisation on the original aortogram and a repeat examination was necessary. Subclavian endarterectomy was undertaken in each case and irreversibly ischaemic digits were managed by local amputation in two cases. Direct surgery to remove the site of embolisation was preferred to bypass or transposition procedures. No further embolic episodes have been recorded with a follow-up of 6 months to 3 years. The important diagnostic features and options in surgical management of this syndrome are discussed.

Refractory supra-ventricular tachyarrhythmias due to early posterior pericardial effusion following open-heart surgery

Three cases are presented of supra-ventricular tachyarrhythmias following open heart surgery refractory to direct current cardioversion and pharmacological treatment. Echocardiography demonstrated a moderate to large posterior pericardial effusion in each case. Surgical evacuation of the effusion was followed by reversion to sinus rhythm.

Spontaneous closure of a traumatic interventricular septal defect following a penetrating chest injury

A case of spontaneous closure of a traumatic ventricular septal defect following a penetrating cardiac injury is presented. The surgical management of these lesions is discussed.

Synthesis of orcinol tridepsides and aphthosin, an orcinol tetradepside

Total syntheses of the lichen depsides, gyrophoric acid, methyl gyrophorate, 4-O-methylgyrophoric acid, tenuiorin, umbilicaric acid, hiascic acid and aphthosin are described.

2-O-Acetyltenuiorin, a new tridepside from the lichen Pseudocyphellaria australiensis

The tridepside 2-O-acetyltenuiorin (4) has been isolated from the lichen Pseudocyphellaria australiensis.� The structure of this compound followed from spectroscopic data and was corroborated by permethylationwith diazomethane to give methyl 2-0-acetyl-2',2"-di-O-methylgyrophorate (5). Total synthesis of 2-O-acetyltenuiorin confirmed the assigned structure. This new tridepside was also shown to occur in several other Pseudocyphellaria species as well as two Peltigera species.