Coronary artery bypass surgery: current practice in the United Kingdom

OBJECTIVE

To assess current clinical practice in coronary artery bypass surgery and compare it with a previous survey conducted five years ago.

SETTING

United Kingdom.

DESIGN

Postal questionnaires were sent in March 1993 to 120 consultant cardiac surgeons currently performing coronary artery bypass surgery. 104 (87%) were returned by May 1993.

RESULTS

The 104 surgeons who returned the questionnaire performed an estimated total of 25,234 coronary artery bypass operations in 1992 with an average case load per surgeon similar to that in 1987 (243 v 214, NS). The internal mammary artery was regarded as the conduit of choice by 101 surgeons (97%) and was used in 93% of bypass grafts to the left anterior descending coronary artery compared with 73% in 1987 (p < 0.001) but only in 7% of grafts to the circumflex and right coronary systems. There was also a significant increase in the number of surgeons using both internal mammary arteries (88% v 59%, p < 0.01) but only a small increase in those using the internal mammary artery as a sequential graft (55% v 44%, NS). The age of the patient remains one of the main contraindications to the use of the internal mammary artery (40%), together with insufficient mammary flow (42%), endarterectomy (22%), and unstable angina (17%). The right gastroepiploic and inferior epigastric arteries were used only occasionally (3%) when the internal mammary artery or the saphenous vein were not available. Most surgeons (96%) still advocate the use of aspirin to enhance graft patency, with 87% of surgeons continuing treatment indefinitely, compared with 50% in the previous survey (p < 0.001). As for methods of myocardial protection, 72% of surgeons used cardioplegic arrest whereas 28% preferred intermittent aortic cross clamping and fibrillation.

CONCLUSIONS

It is the consensus among British cardiac surgeons that the internal mammary artery is the graft conduit of choice. Its use has been significantly extended over the past five years (1987 to 1992) suggesting a quick response to advancing scientific knowledge. The use of alternative arterial conduits is still limited, perhaps as a reflection of the relative lack of information on their long-term performance. The recently advocated technique of retrograde cardioplegia and continuous warm cardioplegia is not yet popular.

Myocardial revascularisation in the elderly: complementary roles for coronary angioplasty and bypass grafting

Coronary artery disease is a common finding, responsible for substantial morbidity and mortality in the elderly. Despite this, there is a general reluctance to refer elderly patients for further investigation as the perceived risks are thought to outweight any potential benefit. This is not however borne out by the available evidence, which suggests that revascularisation procedures carry little additional risk in appropriately selected elderly patients. Chronological age per se should, therefore, no longer be a bar to myocardial revascularisation.

How to do it. A modified battery-powered toothbrush for coronary artery endarterectomy

A modified battery-powered toothbrush for performing coronary artery endarterectomy is described. The device facilitates the dissection of the atheromatous core, is safe and inexpensive.

Phosphatidylcholine-coated chest tubes improve drainage after open heart operation

Occlusion of chest drainage tubes by thrombus is not uncommon after open heart operations. It has been suggested that by coating the tube with phosphatidylcholine (PC), the most prominent phospholipid in the erythrocytes outer membrane, it may be possible to overcome the blood-material interaction responsible for thrombus formation. To test this hypothesis 102 patients (75 males; mean age, 57 +/- 10 years) were randomly allocated to receive either PC-coated or noncoated 32F chest drainage tubes. Preoperative status, type and length of operation, and duration of drainage were similar in the two groups as was postoperative blood loss. Patients receiving PC-coated tubes, however, had less residual blood clot in the tube after removal (0.7 +/- 0.1 versus 3.1 +/- 0.3 g; p < 0.001), a reduced incidence of pericardial effusions (17.6% versus 41.2%; p < 0.01), fewer postoperative supraventricular arrhythmias (2 of 51 versus 10 of 51; p < 0.002), and a shorter hospital stay (8.4 +/- 0.3 versus 9.7 +/- 0.5 days; p < 0.05). Late cardiac tamponade developed in 2 patients in the noncoated group 6 and 10 days postoperatively, which required reexploration. The data show that PC-coated chest drainage tubes are less susceptible to occlusion by thrombus and their use is associated with a significant reduction in postoperative morbidity.

Surgical preparation induces injury and promotes smooth muscle cell proliferation in a culture of human saphenous vein

OBJECTIVE

The aim was to investigate the influence of vessel wall injury, incurred during routine vein preparation, on smooth muscle cell proliferation.

METHODS

A newly developed quantitative organ culture was used, in which segments of human saphenous vein were cultured in medium containing 30% fetal bovine serum and 1 microCi.ml-1 of [3H]thymidine for up to 14 d. Endothelial integrity was measured by scanning electron microscopy and medial cell viability by adenine nucleotide concentrations. Cell proliferation was measured by DNA concentration, global incorporation of [3H]thymidine, and by counting labelled cells in autoradiographs of transverse sections.

RESULTS

Surgical preparation led to endothelial injury and reduced adenine triphosphate concentration by 60%. Surgically prepared veins also suffered a significant decline in DNA concentration during culture, which implied that injury led to cell necrosis. Surgically prepared veins showed 2.1- and 2.7-fold greater global incorporation of [3H]thymidine than freshly isolated veins after 7 and 14 d in culture, respectively, which corresponded with a 23-fold and 11-fold greater abundance of thymidine labelled cells in the medial layer. Intimal thickening and the numbers of total and thymidine labelled cells in the intimal layer were similar.

CONCLUSIONS

The data show that injury incurred during routine surgical preparation is associated with enhanced medial smooth muscle cell proliferation. The effect of injury was most probably to permit an increased response of medial smooth muscle cells to serum derived mitogens.

Comparison of response to injury in organ culture of human saphenous vein and internal mammary artery

Autologous saphenous vein grafts, unlike internal mammary artery grafts, suffer many late occlusions as a result of excessive proliferation of vascular smooth muscle cells and the superimposition of atheroma on the resulting thickened intima. We investigated the possible basis of this difference using organ cultures. Internal mammary artery segments and freshly isolated and surgically prepared saphenous vein segments were obtained from patients undergoing coronary artery bypass grafting. Internal mammary artery and freshly isolated vein segments showed a high degree of endothelial coverage and medial cell viability that were maintained during culture. Surgically prepared veins showed partial endothelial denudation and medial cell injury, both of which tended to be reversed during culture. Neointimal thickening was greater in surgically prepared vein (72 +/- 13 microns; n = 11) than in freshly isolated vein (44 +/- 8 microns; n = 10) or internal mammary artery (34 +/- 4 microns; n = 13) segments. The occurrence of proliferating cells in the medial layer was also significantly greater in surgically prepared vein (2.8 +/- 1.0/mm; n = 11) than in freshly isolated vein (0.8 +/- 0.3/mm; n = 9) or internal mammary artery (0.6 +/- 0.3/mm; n = 10) segments. The data show that although the smooth muscle proliferation was similar in undamaged saphenous vein and internal mammary artery, it was significantly greater in damaged vein. This implies that the greater intimal proliferation seen in saphenous vein grafts may arise not from intrinsic differences in arterial and venous smooth muscle cells but from a greater susceptibility to injury.

Effects of external stenting on wall thickening in arteriovenous bypass grafts

Late occlusion of the saphenous vein graft appears to result in part from wall thickening as an adaptation to increased mean wall stress. Using an established pig model of arteriovenous bypass grafting, the effect of reducing wall stress with an external porous polytetrafluoroethylene stent was investigated. Segments of autologous saphenous vein were implanted by end-to-end anastomoses into both carotid arteries, with one graft supported by a stent 4 mm in diameter. Increases in graft wall dimensions were quantified 4 weeks later by computer-aided planimetry of transverse histological sections. The contribution of hyperplasia (i.e., cell proliferation) to the changes observed was further clarified by measurements of DNA concentration. All grafts showed an increase in external size, but this was restricted by stenting. All grafts also showed an increase in cross-sectional area of the tunica media and tunica intima that was only partly accounted for by an increase in DNA concentration, which indicated that both hyperplasia and hypertrophy had occurred. Stented grafts showed less enlargement of the media but greater enlargement of the intima. Overall wall size was therefore similar in stented and unstented grafts. Stented grafts showed less increase in DNA concentration than unstented grafts. In stented grafts, the residual luminal cross-sectional area was significantly less than in unstented grafts. The data show that external stenting reduces medial enlargement and hyperplasia but increases encroachment of the intima into the lumen. Because final luminal size is thought to be of paramount importance in maintaining long-term patency, external stenting is unlikely to be of benefit.

Heparin in coronary artery disease: new uses for an old drug

The role of heparin in the treatment of coronary artery disease remains unclear. Although of benefit in unstable angina and the prevention of acute occlusion following angioplasty, its value as adjunctive therapy in myocardial infarction is limited. Further studies are needed to assess the effect of heparin on angioplasty restenosis and late venous graft occlusion.

Saphenous vein graft failure: etiologic considerations and strategies for prevention

Occlusion of saphenous vein coronary artery bypass grafts remains a significant clinical problem. Early occlusion can be minimized by optimizing surgical techniques and by antithrombotic treatments. Unfortunately, no modification of surgical technique or drug therapy has been shown to reduce late vein graft occlusion. This results from excessive proliferation of vascular smooth muscle cells and the superimposition of atheroma on the resulting thickened intima. Understanding the basic mechanisms underlying this response may be helpful in developing strategies to reduce vein graft occlusion.

Intimal proliferation in an organ culture of human internal mammary artery

OBJECTIVE

Intimal smooth muscle cell proliferation is an early feature of atherosclerosis. Its progression is difficult to monitor in humans and previous studies have mostly relied on necropsy material. The aim of this study was therefore to establish whether intimal proliferation occurred in an organ culture of human internal mammary artery.

METHODS

Segments of freshly isolated internal mammary artery were maintained din standard tissue culture medium containing 30% calf serum for 14 d. Tissue viability (measured by ATP concentration) was maintained during processing and throughout the culture period [211(SEM 28) nmol ATP.g-1 wet weight on d 1 v 208(27) on d 14].

RESULTS

Histological transverse sections of cultured internal mammary artery showed the development of a neointima containing smooth muscle cells identified by immunocytochemistry for alpha actin. Pulse labelling of cultures with [3H]-thymidine showed proliferating cells predominantly in a neointimal layer with few dividing cells in the media. Cultured de-endothelialized vessels showed less neointimal thickening than cultured freshly isolated vessels [16(3) v 36(5) microns, p < 0.0025] as well as a reduced number of dividing cells per mm of neointimal length [3.1(0.6) v 5.5(1.1), p < 0.05].

CONCLUSIONS

Intimal proliferation occurred in organ culture of internal mammary artery. There is evidence for a factor derived from the endothelium, which may be important in the development of intimal proliferation.

Overcoming perioperative spasm of the internal mammary artery: which is the best vasodilator?

After mobilization, vasospasm often reduces flow through the internal mammary artery. An established method of relaxing the artery and increasing flow is to wrap it in a papaverine-soaked swab. To our knowledge the ability of other topical vasodilators to overcome spasm of the internal mammary artery has not been studied clinically. In 50 patients in whom the left mammary artery was used for myocardial revascularization, we have investigated the effect of five agents on internal mammary artery free flow. The agents investigated were normal saline, papaverine, nifedipine, glyceryl trinitrate, and sodium nitroprusside. Under controlled hemodynamic conditions, free flow was measured before any pharmacologic intervention and a median of 18.5 minutes after the pedicle had been sprayed with one of the five agents. Normal saline produced a small increase in flow from a median of 23 ml/min (range 17 to 88) to 38 ml/min (20 to 84) (not significant), whereas a significant increase occurred with papaverine, from 25 (16 to 78) to 43 ml/min (34 to 112) (p less than 0.01). Nifedipine and glyceryl trinitrate raised free flow by almost threefold, from 23 (14 to 66) to 71 ml/min (45 to 118) and from 23 (14 to 58) to 62 ml/min (46 to 126), respectively (both p less than 0.001). Sodium nitroprusside, however, with an increase in flow from 26 (10 to 58) to 108 ml/min (46 to 196), 250% over control, proved to be more effective than nifedipine and glyceryl trinitrate (p less than 0.05). We therefore recommend the topical use of sodium nitroprusside to relieve perioperative spasm of the internal mammary artery.

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.

Adverse hemodynamic effects of pericardial closure soon after open heart operation

The short-term hemodynamic effects of pericardial closure on cardiac function were studied during steady-state anesthesia and ventilation in 10 patients (6 men) (mean age, 59 +/- 9 years) who underwent an open-heart valve operation. Observations were made after the heart was decannulated, both while the pericardium was open and after it had been closed, and then after closure of the chest after the pericardium had been reopened by removing the pericardial suture through the chest wall. The effect of closing the pericardium before closing the chest was an immediate reduction in cardiac output (thermodilution) of 1.39 +/- 0.24 L/min from 5.09 +/- 0.40 L/min (p less than 0.001). The heart rate remained stable, but there was a decrease in stroke volume of 29% and an increase in systemic vascular resistance of 34% (both, p less than 0.01). The mean arterial pressure increased slightly by 2% (not significant). Opening the pericardium (1.5 to 2 hours after the end of the operation) while the chest remained closed was followed by an increase in cardiac output of 1.33 +/- 0.15 L/min from 4.12 +/- 0.62 L/min (p less than 0.001). As the heart rate and the mean blood pressure changed insignificantly, there was an increase in stroke volume of 15 +/- 3 mL from 53 +/- 5 mL and a reduction in systemic vascular resistance of 473 +/- 83 dyne . s . cm-5 from 1,721 +/- 181 dyne.s.cm-5 (both, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Congenital ventricular septal defect presenting as rupture of the ventricular septum subsequent to myocardial infarction

A 74-year-old female presented in cardiogenic shock four weeks following a severe episode of ischaemic chest pain. Physical examination was suggestive of a ventricular septal defect, and this was confirmed by cross-sectional echocardiography and right heart catheterisation. As the resting electrocardiogram was consistent with an extensive anterior myocardial infarct of indeterminate age, a diagnosis of ventricular septal defect subsequent to infarction was made and the patient taken to the operating theatre for urgent repair. At operation, however, the defect was found to be congenital in origin.

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.

Winner of the ESVS prize 1990. Smooth muscle cell proliferation in response to injury in an organ culture of human saphenous vein

The principal cause of late vein graft occlusion is intimal smooth muscle cell proliferation, the underlying basis of which remains an enigma. Early theories implicating platelet activation now appear untenable since intimal proliferation progresses after endothelial repair, and is little influenced by antithrombotic treatments. We developed an organ culture of human saphenous vein to investigate the basis of intimal proliferation in a preparation which preserved the anatomical relationships of endothelium, smooth muscle and extracellular matrix. Tissue viability remained high during culture for up to 14 days and intimal smooth muscle proliferation occurred. The removal of endothelium reduced intimal thickening in cultured veins from 26 +/- 5 to 6 +/- 3 microns and also reduced the number of intimal cells/mm labelled with [3H]-thymidine from 12 +/- 4 to 3 +/- 1 (both p less than 0.01, n = 10). Surgical preparation of vein resulted in significant injury to medial smooth muscle cells, which was only partially reversed during culturing. Surgical preparation did not affect intimal proliferation, but stimulated medial proliferation from 3 +/- 1 to 32 +/- 9 [3H]-thymidine-labelled cells/mm (p less than 0.01, n = 11). These experiments reveal evidence for proliferation enhancing factors derived from endothelium and injured smooth muscle cells, which probably participate in intimal proliferation in vein grafts. Inhibiting their action may therefore present new possibilities for therapy.

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.

Adverse hemodynamic effects and echocardiographic consequences of pericardial closure soon after sternotomy and pericardiotomy

The acute hemodynamic and echocardiographic effects of pericardial closure on cardiac function were studied in 11 pigs during steady-state anesthesia and ventilation. Observations were made after sternotomy, both while the pericardium was open and after it had been closed, and then after closure of the chest, after the pericardium had been reopened by removing the pericardial suture through the chest wall. In five pigs, further observations were made when a suture was tightened to close the pericardium while the chest remained closed. Closure of the pericardium when the chest was open reduced cardiac output by 14% and mean stroke volume by 19% (both p less than 0.05). Systemic vascular resistance increased by 15% when the pericardium was closed while the chest was open (NS), and increased by 19% when it was closed while the chest was closed (p less than 0.05). Heart rate did not change significantly, and the systemic blood pressure was maintained (-8%, NS). All these effects were reversed by opening the pericardium. Intrathoracic epicardial echocardiographic monitoring of the left ventricle showed that its end-diastolic dimension increased (by 11%, p less than 0.05) when the pericardium was opened. After chest closure, paradoxical motion of the interventricular septum was consistently demonstrated only during ventilation, and it was not related to whether or not the pericardium was open. This study suggests that cardiac function may be impaired by pericardial closure after cardiac surgery because of some degree of constriction of the heart chambers, although acute circulatory responses compensate for the mild decrease in stroke volume. Monitoring of blood pressure alone cannot document the subtle circulatory changes induced by pericardial closure, and therefore it is not a reliable guide to decisions of whether to close the pericardium or leave it open in individual patients.

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.

Preparation of the internal mammary artery

The internal mammary artery is the best currently available conduit in coronary artery bypass surgery. It is a living arterial graft with intact smooth muscle and its efficiency as a conduit therefore depends to a large extent on the way it is mobilized and prepared for grafting. This article discusses the anatomical, technical and pharmacological aspects of the surgical preparation of the internal mammary artery for coronary grafting.

A fiber-optic retractor for harvesting the internal mammary artery

A retractor for exposure and dissection of the internal mammary artery incorporating a fiber-optic transillumination system is presented. The device, which can be converted to a standard sternal retractor, has also proved valuable in improving illumination during procedures on the mitral valve and in facilitating dissection of fibrous adhesions from the anterior surface of the heart at reoperation.

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.

Severe stenotic scar contracture of the Microvel Hemashield right-sided extracardiac conduit

We report 2 patients who developed severe scar contracture of a Microvel Hemashield valveless right-sided extracardiac conduit implanted 14 months earlier. In both cases, the diameter of the conduit was reduced along its entire length, with the prosthetic material plicated inward by retraction and organization of connective fibrous tissue on either side of the conduit.

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.

Extended use of a pulmonary homograft for right ventricular outflow tract reconstruction

When a pulmonary homograft is used for reconstruction of the right ventricular outflow tract a patch or tube extension is usually required to close the gap in the right ventriculotomy. We describe here a simple method by which a large patch can be tailored from the homograft using the distal main pulmonary artery and its branches.

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.

The future of saphenous vein as a coronary artery bypass conduit

Continuing widespread use of autologous saphenous vein for coronary artery bypass grafting seems unavoidable despite its poor-term patency. We review here the evidence that platelet activation is responsible for early and late vein graft occlusion and conclude that other mechanisms probably contribute to late occlusions. We suggest that a rational strategy to improve vein graft patency should include: improved endothelial preservation during surgical implantation; use of better antiplatelet agents, in particular those which prevent platelet adhesion as well as aggregation; reduction of risk factors including serum cholesterol; and application of agents (e.g. heparin) which inhibit smooth muscle cell proliferation directly. We draw parallels between the pathogenesis of vein graft occlusion and coronary atherosclerosis and suggest that testing strategies for improving vein graft patency may also shed light on atherogenesis.

Post-infarction ventricular septal defect: the importance of right ventricular coronary perfusion in determining surgical outcome

Mortality from a post-infarction ventricular septal defect (VSD) can be reduced by surgery, selection for which would be helped by knowledge of factors affecting the postoperative prognosis. We reviewed our 9-year experience (1978-1987) of 40 surgically treated patients, comparing preoperative characteristics in those who died postoperatively (n = 15, 37%) and those who survived (n = 25, 63%), all still alive. Sex, age, infarct size as assessed by peak serum creatine kinase values, left ventricular end-diastolic pressure and pulmonary/systemic flow ratio (2.9 +/- 0.2 vs 3.1 +/- 0.3) were similar. Survivors had a lower incidence of inferior infarct than those who died (6, 24% vs 9, 60%, P less than 0.05), a lower incidence of cardiogenic shock (7, 28% vs 10, 67%, P less than 0.05), less elevation of right ventricular end-diastolic pressure (10.1 +/- 0.9 vs 14.7 +/- 1.0 mm Hg, P less than 0.01) and less impairment of right ventricular coronary supply as determined by a coronary angiography-derived myocardial score (0.9 +/- 0.3 vs 4.7 +/- 0.7, P less than 0.001). The data suggest that right ventricular coronary perfusion influences prognosis. The proposed angiographic score may help to identify preoperatively those patients most likely to benefit from surgery.

A simple, inexpensive method of heart retraction during coronary artery bypass surgery

A method of heart retraction for coronary artery bypass surgery is described. The technique improves coronary artery exposure during grafting and in addition is simple, safe, and inexpensive.

Left atrial ball thrombus: echocardiographic features and clinical implications

The echocardiographic features of left atrial ball thrombus associated with mitral stenosis are reviewed, and some previously unpublished cross-sectional echocardiographic findings presented. In one patient who had a large free-floating ball thrombus there was variation in its echocardiographic appearance; the thrombus was removed uneventfully at surgery. In another patient who had a pedunculated but immobile ball thrombus, a stalk was identified which attached it to the inter-atrial septum; this patient died suddenly before surgery could be performed, due to detachment of the thrombus and obstruction of the mitral valve orifice. Cross-sectional echocardiography is clearly superior to M-mode imaging in the detection of atrial thrombi, and variable appearances may help differentiation of thrombus from myxoma. Whether or not a ball thrombus appears mobile, emergency thrombectomy and mitral valve replacement is indicated, because of the risk of obstruction of the mitral valve.

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.

A report and review of recurrent left atrial myxoma: not always such 'a benign tumor'

We report a patient whose left atrial myxoma recurred three times and review 28 other reports of recurrent myxoma. Inadequate resection and multifocal growth appear to be two separate causes for recurrence.

Endothelial function can be preserved during cryo-storage of human saphenous vein

Endothelial functional integrity was quantified in human saphenous vein by measurement of stimulated (vortex-mixing) rates of prostacyclin production. Prostacyclin production was not inhibited by dimethylsulphoxide (DMSO), glycerol or sucrose at concentrations normally used for cryopreservation. Rapid freezing followed by storage for 3-4 weeks and thawing of veins pretreated with 15% (v/v) dimethylsulphoxide significantly impaired prostacyclin production. In contrast, slow freezing and thawing in the presence, but not the absence, of DMSO led to complete retention of prostacyclin production. We conclude that endothelial function can be preserved during cryostorage.

Nature and pressure dependence of damage induced by distension of human saphenous vein coronary artery bypass grafts

Surgical preparation of human saphenous vein for coronary artery bypass grafting involving distension and storage in iso-osmotic sodium chloride solution reduced tissue adenosine triphosphate (ATP) (mean(SEM] concentration from 280(20) nmol.g-1 wet wt (n = 25) to 140(30) nmol.g-1 wet wt (n = 12) and the adenosine triphosphate to adenosine diphosphate (ATP:ADP) concentration ratio from 2.4(0.1) to 1.2(0.2). Since removal of endothelium from freshly isolated vein did not affect ATP concentration or ATP:ADP ratio, these changes quantified medial damage. Distension of the vein at a pressure of 150 mmHg caused no change in ATP concentration or ATP:ADP ratio, but these values were reduced progressively by distension at 300 mmHg and 600 mmHg. Damage was not reversed but was exacerbated by subsequent incubation of the distended vein in blood. Distension of the vein at 600 mmHg caused release of tissue lactate dehydrogenase. The data show that acute medial damage can result from distension of the vein but that this does not occur at pressure equivalent to normal arterial pressure. Distension induced medial damage is unlikely to be rapidly reversible.