Reoperative Coronary Bypass Research Articles

Evaluations of factors affecting the outcome of redo coronary bypass surgery and long term results: A retrospective observational study

Aim: Advanced atherosclerosis of coronary arteries, existence of patent arterial grafts, redo sternotomy, shortage of available vascular conduits, difficulty of exploration of the coronary vessels are the factors that render the coronary reoperations challenging and they may be responsible of higher mortality and morbidity rates of reoperations. The aim of this study is to evaluate the factors that affect the progression of atherosclerotic coronary artery disease in the post-operative period of coronary artery bypass surgery which results in a redo operation. Methods: A number of 115 patients who underwent coronary bypass re-operations between January 1997 and August 2007 were included. Patients were divided into two groups as follows: Group 1 was the risk factor positive group, Group 2 was the risk factor negative group. The time interval between the initial operative procedure and the redo operation was calculated and the effect of risk factors upon this time interval and the mortality rates were evaluated. Results: The time interval between the first operative procedure and the reoperation was 77.31 months in Group 1 and 93.88 months in Group 2. Smoking had a more negative effect on the reoperation rate compared to the other risk factors (p=0.025). Mortality rate was higher in the risk factor positive group (p=0.027). Preoperative EF had a significant effect on the mortality rates (p=0.018). Conclusion: The presence of any risk factor for CAD increases the chance of having a reoperation. Off-pump surgery technique should be chosen in appropriate cases to lower the mortality risk of redo CABG operations and choosing the combined cardioplegia administration in on-pump redo coronary bypass operations would lower the mortality rate as well.

Composite Y-Grafting Using the Left Internal Thoracic Artery: Survival and Angiography in 198 Cases.

Extended left internal thoracic artery (LITA) harvesting allows maximal grafting to the anterior and lateral walls with a single ITA conduit. This study evaluates outcomes following the use of a LITA Y graft as the primary grafting strategy. Patients who underwent LITA composite Y-grafting (n=198) between 1995 and 2009 were identified from a cardiac surgical database. Follow-up (mean 13.1 years) was obtained by cross-reference with the state death registry and local cardiology databases. Operative mortality was zero in the 168 patients who underwent isolated CABG and was 3.5% overall. There were no episodes of perioperative myocardial infarction. Kaplan-Meier 10-year survival was 75.9%. Independent predictors of worse late survival were age, diabetes, chronic obstructive pulmonary disease and pre-existing left ventricular dysfunction. There were 53 episodes of post-discharge angiography at an average of 5.8 years post LITA Y grafting. Twenty cases of LITA Y graft failure were identified, predominantly affecting the free limb (n=15). The ratio of symptom driven angiography to Y graft failure increased over time. Eighteen patients required revascularisation, percutaneous intervention in 15 and reoperative coronary bypass in three. Left Internal Thoracic Artery Y grafting is a feasible revascularisation strategy with satisfactory outcomes. These are comparable to other arterial composite graft configurations. A LITA Y allows efficient conduit use without compromising the in situ LITA graft.

Internal mammary artery conduit re-use in coronary artery bypass grafting: Case series and review

Left internal mammary artery (LIMA) conduit is the gold standard graft for coronary artery bypass. Due to excellent patency rates with this graft it can safely be used in re-operative coronary bypass surgery. The safety of this technique is demonstrated with our report of re-used LIMA conduits in patients with extensive coronary artery disease (CAD). The success of this technique was evaluated by postoperative computerized tomographic angiography which demonstrated patent conduits and flow to the left anterior descending artery (LAD).

Pseudoaneurysms of the Heart

Case 1 : An 85-year-old man with a history of ischemic cardiomyopathy and recent reoperation coronary bypass surgery was noted on a routine follow-up echocardiogram to have a 25×25-mm fluid-filled extracardiac mass adjacent to the basal inferolateral wall of the left ventricle (Figure 1). Cardiac computed tomography (CT) identified the structure to be a pseudoaneurysm of a saphenous vein graft to an obtuse marginal branch of the left circumflex coronary artery. How should this patient be managed? Figure 1. Saphenous vein graft (SVG) pseudoaneurysm in an 85-year-old man after recent reoperation coronary artery bypass surgery. The pseudoaneurysm was visible as a mass (arrow) in the left atrioventricular (AV) groove on the chest x-ray ( A ). Transthoracic echocardiography ( B ) demonstrated a vascular mass (arrow) adjacent to the basal lateral wall. Cardiac computed tomographic angiography ( C ) demonstrated the pseudoaneurysm (arrow) connecting to the SVG by a narrow neck with contrast enhancement (light gray) and some thrombus (dark gray). Four-chamber view ( D ) demonstrating the pseudoaneurysm (arrow) in the left AV groove; a magnified view ( D , inset) demonstrates the pseudoaneurysm connected to the SVG via a narrow neck (arrow) with active contrast extravasation (red outline) contained by thrombus (white outline). Invasive angiography showing contrast extravasation ( E ) into the pseudoaneurysm (arrow) and postintervention angiogram demonstrated successful occlusion of the pseudoaneurysm ( F ). LA indicates left atrium; LV, left ventricle. Case 2 : A 27-year old man with prior homograft aortic valve replacement developed recurrent endocarditis (Figure 2). Echocardiography noted a periaortic valvular fluid collection concerning for abscess or valvular dehiscence. However, Doppler signal to and from the fluid collection connecting to the left ventricular outflow tract also raised concern for pseudoaneurysm. Cardiac CT confirmed the structure to be a 37×32-mm pseudoaneurysm involving the left coronary cusp of a trileaflet homograft prosthetic aortic valve just below the takeoff of …

Seguimento a longo prazo de pacientes submetidos à revascularização do miocárdio com uso exclusivo de enxertos arteriais

To evaluate the long-term results of the coronary artery bypass grafting with exclusive use of arterial grafts for patients with triple vessel disease. We evaluated 136 patients who underwent isolated coronary artery bypass grafting between January 1995 and December 1997. 353 grafts were used for revascularization of 449 arteries (mean: 3.30 per patient). Grafts used were left internal thoracic artery (99.2%), right internal thoracic artery (56.6%), radial artery (87.5%), right gastroepiploic artery (20.5%) and one inferior epigastric artery. 76 (55.8%) patients received composite grafts ('Y' shape) and 66 (48.5%) patients received sequential anastomoses. Hospital mortality was 4.4%. In the long-term follow-up (9.5 to 12.8 years), 82.1% of the patients were free of cardiac events. 20 (17.9%) patients had hospital readmission due to cardiac events: 15 presented angina and five presented acute myocardial infarction, and three of them presented associated heart failure. Eighth (7.1%) patients needed coronary reintervention: one of them underwent coronary bypass reoperation and the others underwent coronary angioplasty with stent. Estimated probability of cardiac event-free was 98.2%, 95.4% e 84.2% at 1, 5 and 10 years follow-up respectively. There were 16 (14.2%) late deaths and four of them (3.6%) were cardiac-related. Actuarial 12.8-year-survival of all deaths was 85% in this group. Coronary artery bypass grafting with exclusive use of arterial grafts is a safe procedure for patients with triple vessel coronary disease with good long-term results.

Surgical Repair of a Left Subclavian Artery Aneurysm Causing Stenosis of a Left Internal Mammary Graft A Case Report

Subclavian artery aneurysms are extremely rare, accounting for approximately 0.1% of peripheral artery aneurysms. We present a case of a proximal left subclavian arterial aneurysm in a patient status post previous coronary artery bypass grafting; the aneurysm was complicated by involvement of the left internal mammary artery that had been previously utilized to revascularize the left anterior descending artery. Ostial stenosis of the internal mammary artery secondary to the aneurysm was present. Simultaneous reoperative coronary bypass surgery and repair of the left subclavian aneurysm was performed, with a good result. This is the second case reported in the literature of concomitant subclavian artery aneurysm repair and coronary revascularization.

The radial artery in reoperative coronary bypass surgery:.

Failure of saphenous vein grafts (SVG) is a significant cause for coronary reoperation (redo CABG). The radial artery (RA) because of its availability, and versatility is well suited to use (together with internal thoracic arteries (ITA) in redo CABG, especially to replace failed SVG. We evaluated our experience where the RA was a major conduit in redo CABG over the past 5 years. From July 1996 to June 2002, 590 consecutive patients underwent redo CABG where one or both RA(s) were used, together with LITA or RITA. The mean age was 67.3 years, 82% were male, and 19% diabetic, 419 (71%) had Class III or IV angina, 135 (23%) had left main stenosis, and 210 (36%) had an LVEF < 0.50. There were a total of 877 RA conduits (303 single, 287 bilateral), 518 new LITA or RITA. A mean of 2.8 new distal anastomoses constructed 92% (2.6 per patient)of the arterial grafts. Follow-up was at 1 month, 3 months, and then yearly. The results were compared with 6466 primary CABG performed in the same time frame, and with a prior cohort of 741 consecutive patients having redo CABG without an RA in which identical operative techniques had otherwise been used. The 30-day mortality was 3.9% (23 patients). Morbidity was low. Perioperative myocardial infarction occurred in 16 (2.7%) patients, stroke in 10 (1.7%), sternal infection in 10 (1.7%), donor site infection in 2 (0.3%), and IABP use in 23 patients (3.9%)-including 10 preoperatively. The results were better when compared to a prior cohort of 741 patients with redo CABG (1991 to 1996) without use of the RA. The results were inferior to that of the contemporary primary CABG. Operative mortality was 3.9% versus 0.9%, p = 0.002, myocardial infarction 2.7% versus 0.8%, p = 0.03. The use of the RA (together with ITA) in redo CABG achieved total arterial revascularization in 92% of cases and is associated with excellent results, at least equal to or superior to those achieved previously.

Left thoracotomy approach in reoperative off-pump coronary revascularization: bypass grafting from the left axillary artery or descending thoracic aorta.

Reoperative coronary bypass grafting is at high risk. Particularly in redo cases where the patent graft is running near the midline of the sternum, the graft may be exposed to injury by a median sternotomy and subsequent dissection. Whereas, off-pump bypass grafting from the left axillary artery or descending thoracic artery by a left thoracotomy approach is safe for preventing graft damage. From March 1998 to February 2002, we performed off-pump coronary artery bypass grafting by a left thoracotomy approach in 9 patients. The left axillary artery was used as the inflow vessel in 4 cases, and the descending thoracic aorta in 5. The radial artery was anastomosed proximally to the axillary artery in 4 cases and the descending thoracic aorta in one case. The saphenous vein graft was anastomosed proximally to the descending thoracic aorta in 4 cases. Transdiaphragmatic minimally invasive bypass grafting for the right coronary artery was simultaneously performed in 3 cases. Postoperative cardiac events were ventricular arrhythmia in 6 cases and supraventricular arrhythmia in 3 cases. There was no damage to the patent grafts. Postoperative coronary angiography performed in 8 cases revealed all the grafts to be patent without stenosis. Cardiac symptoms were not found after the operation in any of the cases. These procedures can prevent the injury to patent grafts caused by a median sternotomy, and will be one of the useful strategies for reoperative off-pump coronary artery bypass grafting.

Reoperative Coronary Bypass Surgery Using Normothermic Cardiopulmonary Bypass: Comparison with First-Time Procedures

Redo coronary artery bypass grafting (CABG) is characterized by increased patient risk compared with first-time CABG. The reason for higher risk is not completely understood but it is logically related to inadequate myocardial preservation evidenced by the higher incidence of postoperative low-output syndrome. We compared normothermic cardiopulmonary bypass with cold blood maintenance cardioplegia in both first-time and redo CABGs to determine whether this single approach is appropriate for both instances. Five hundred seventeen consecutive CABG patients were retrospectively reviewed. Four hundred fifty-four first-time CABG procedures were compared with 44 redo procedures. All aspects of the operation were identical including myocardial preservation. Retrospective univariant analysis of both groups followed. Three clinical features distinguished first-time versus redo CABG. These were previous percutaneous transluminal coronary angioplasty (first-time 19% vs redo 71%; P < 0.001), preoperative intra-aortic balloon pump (first-time 38% vs redo 71%; P < 0.001), and Parsonnet risk score (first-time 11.7+/-8.2 vs redo 19.2+/-8.8; P < 0.001). Operative mortality for redo CABG was higher than in first-time procedures (3.4% vs 6.4%; P = not significant), although small sample size limited statistical significance. The length of stay was statistically longer in redo patients (8.7+/-10.8 vs 6.0+/-5.1 days; P < 0.01) and is related to a higher Parsonnet score, increased postoperative pneumonia, and failed percutaneous transluminal coronary angioplasty before redo CABG. We conclude that redo CABG is a different operation from first-time procedures and requires enhanced myocardial preservation. Normothermic cardiopulmonary bypass with cold blood maintenance cardioplegia does not appear to achieve this goal.

Reoperative coronary bypass surgery: Effect of patent grafts and retrograde cardioplegia

Objective: To determine the effects of patent or diseased aorta-coronary bypass grafts and retrograde cardioplegia on mortality during reoperative coronary bypass surgery. Methods: We conducted a retrospective review of prospectively gathered data, supplemented by systematic chart review, of all patients (n = 744) undergoing reoperative coronary bypass surgery at our institution between 1990 and 1997. Independent predictors of survival were determined by stepwise logistic regression analysis. Results: At least one patent or stenosed graft to the left anterior descending artery was present in 50% of patients, to the circumflex territory in 27% of patients, and to the right coronary artery territory in 33% of patients. The previous left anterior descending graft was a saphenous vein in 82% and a left internal thoracic artery in 18% of patients. In-hospital mortality occurred in 42 (5.6%) patients. Patent or diseased grafts of any coronary artery territory did not significantly increase the risk of mortality. Retrograde cardioplegia use increased in more recent years, was more frequent in patients with stenosed grafts, and was associated with improved survival. Independent predictors of mortality were as follows (with odds ratios and 95% confidence intervals in parentheses): failure to use retrograde cardioplegia (odds ratio 2.81; 1.28-6.20), New York Heart Association class (odds ratio 2.69; 1.25-5.81), peripheral vascular disease (odds ratio 2.60; 1.25-5.41), and left ventricular grade (2.07; 1.31-3.27). Conclusions: In this series, patent or stenosed grafts were not associated with an increased risk of mortality during reoperative coronary bypass surgery, possibly because of increased use of retrograde cardioplegia in this patient group. We strongly recommend the routine use of retrograde cardioplegia during redo coronary bypass surgery. (J Thorac Cardiovasc Surg 2001;121:83-90)

PII: S0003-4975(99)01220-5

PII: S0003-4975(99)01220-5

Elimination of cardiopulmonary bypass: a prime goal in reoperative coronary artery bypass surgery.

The purpose of this study was to evaluate morbidity and mortality in reoperative coronary artery bypass surgery using the New York State database. Patients undergoing reoperative coronary artery bypass between January-1995 and December 1996 were included. Patients were operated using cardiopulmonary bypass (CPB group, n = 184) or without cardiopulmonary bypass (non-CPB group, n = 105) by surgeon preference. Groups were compared for preoperative risk factors, postoperative mortality and major complications. Crude mortality was lower in the non-CPB group, despite a higher expected mortality, resulting in a risk-adjusted mortality of 1.3% versus 2.7% for the CPB group (NS). Of non-CPB patients, 91.4% were without complications, while only 72.1% of CPB patients (P < 0.0001) were complication-free. Major complications were significantly reduced in non-CPB patients compared to CPB patients: stroke 0% versus 3.8% (P < 0.04), cardiovascular complications 4.8% versus 15.8% (P < 0.005), other major complications 1.9% versus 10.4% (P < 0.007). Postoperative IABP support was needed in 1.9% of the non-CPB group patients and in 14.2% of the CPB group (P < 0.0007). The main object of reoperative CABG is to relieve symptoms, since the survival benefit of the procedure has not been demonstrated. Performance of reoperative coronary artery bypass surgery without cardiopulmonary bypass significantly reduces morbidity. We conclude that cardiopulmonary bypass should be avoided whenever possible in reoperative coronary bypass surgery.

Testing the Efficacy of Lipid-Lowering Therapy Versus Revascularization: The Time Has Come, or Is It Past Due?

To the Editor: Small, lipid-rich, vulnerable plaques that are angiographically unimpressive and hemodynamically insignificant are responsible for most cases of fatal and nonfatal myocardial infarctions, whereas large, stable plaques that produce angiographically severe stenoses generally result in stable angina but rarely result in myocardial infarction. Accordingly, lipid-optimizing therapy, which stabilizes the vulnerable plaques, may have a major impact on prevention of myocardial infarction and death, whereas revascularization procedures, which are directed at severely stenotic lesions, may not. Therefore, I was particularly struck by the fascinating conclusion by Forrester and Shah1 in Circulation : “Coronary angiography does not identify, and consequently revascularization therapies do not treat, the lesions that lead to myocardial infarction.” Their conclusions, if proven correct, will have enormous implications for the management of coronary artery disease, since coronary angiography has been the gold standard for its diagnosis and revascularization its mainstay of treatment for decades. The United States is home to only 5% of the world’s population but performs almost 50% of the invasive coronary procedures worldwide. Of a total of 900 000 coronary angioplasties performed worldwide in 1994, 404 000 were done in the United States, at an average cost of $21 700 each.2 Another 501 000 coronary bypass surgeries and 1.1 million coronary angiograms were done on Americans the same year, each at an average cost of $44 200 and $10 880, respectively. Revascularization procedures are done in 58% of all acute myocardial infarctions and account for about half the cost of hospital admission for this condition.3 Ironically, …

Reoperations with the right gastroepiploic artery without cardiopulmonary bypass.

The right gastroepiploic artery (RGEA) has been utilized as the bypass conduit on the inferior surface of the heart with a minimally invasive approach. Fourteen patients had reoperative coronary bypass surgery for severely symptomatic single-vessel disease of the right coronary artery. All surgeries were performed since May 1996. A small mid-line incision including splitting of the lower sternum gave excellent exposure. The inferior surface of the heart was dissected to expose and stabilize the target vessel. The heart rate was controlled with a diltiazem drip. Cardiopulmonary bypass was not necessary in any case. The right coronary artery was bypassed in three patients, the posterior descending artery branch in ten patients, and the terminal circumflex of the left coronary artery in one. After grafting, patency of the anastomosis was demonstrated by Doppler echocardiogram. Two patients had left anterior descending artery (LAD) grafts with LIMA (left mammary artery) and RGEA grafts performed simultaneously with two port access incisions. No patient had perioperative mortality or complications. No patient had recurrent angina. Doppler color echocardiographic imaging studies before discharge confirmed patency of the graft in 13 of 14 cases. In one case, the gastroepiploic artery could not be visualized. Angiographic visualization was positive in seven cases; seven patients were not studied yet. The gastroepiploic artery is an excellent conduit for vascularization of the inferior aspect of the heart. The operation can be done with a minimally invasive technique and without the use of cardiopulmonary bypass. This approach seems especially applicable in selective reoperative cases.

Effect of Aprotinin on Smooth Muscle Cell Proliferation, Migration, and Extracellular Matrix Synthesis

Aprotinin (AP) is a plasmin inhibitor commonly used to limit bleeding during reoperative coronary bypass surgery. The effect on smooth muscle cell (SMC) behavior and the development of intimal hyperplasia has not been evaluated. This study examines the effect of AP on SMC proliferation, migration, and extracellular matrix synthesis. Bovine aortic SMCs (three to five passages) plated at 5 × 104cells/ml were treated with 1.0, 10, 100, and 1000 μg/ml AP. Proliferation was measured as micrograms of DNA per well, after 3 days in culture. SMC migration was measured after treatment with mitomycin C (20 μg/ml, to study migration in the absence of proliferation) by means of a fence assay. Extracellular matrix was quantitated utilizing a tritiated proline assay and corrected for cell density (cpm/μg DNA). Data are presented as means ± SEM; ANOVA and post hoc Tuckey test were used to test for significant differences. AP stimulated SMC proliferation at dosages of 100 μg/ml (353 ± 6 μg DNA, SMC control vs 440 ± 11, 100 μg/ml;P< 0.05) and 1000 μg/ml (353 ± 6, SMC control vs 503 ± 14, 1000 μg/ml;P< 0.01). AP concentrations less than 100 μg/ml had no effect on SMC proliferation. A dose–response relationship existed between AP and SMC migration. AP doses as low as 10 μg/ml increased SMC migration from 66 ± 4 mm2(control SMC) to 90 ± 4 mm2(P< 0.02) while the maximal dose of AP (1000 μg/ml) produced an almost twofold increase in migration (66 ± 4, SMC control vs 113 ± 3, 1000 μg/ml group;P< 0.0001). AP had no effect on extracellular matrix synthesis. AP stimulated vascular SMC migration and proliferation but not matrix synthesisin vitro.These data suggest that AP could augment the development of intimal hyperplasia following bypass surgery.

Coronary-pulmonary steal syndrome

The development of an internal thoracic artery-pulmonary artery fistula after operation is a rare entity of no clear etiology. We report a patient who underwent coronary bypass reoperation, presented 3 years later with angina on exertion, and upon investigation was found to have an internal thoracic artery-pulmonary artery fistula. This patient was managed conservatively.

Durability of emergency coronary artery bypass for complications of failed angioplasty

Although emergency coronary artery bypass for complications of percutaneous transluminal coronary angioplasty (PTCA) has proved to be a relatively successful ‘bail-out’ procedure, little is known about the durability of revascularization under these potentially disastrous circumstances. The authors therefore retrospectively examined their results with this procedure. Emergency coronary artery bypass for complications of PTCA was performed in 112 patients between 1 January 1984 and 19 May 1992. Fifteen patients underwent PTCA for acute myocardial infarction. Eleven patients (9.8%) were stable, and underwent emergency coronary artery bypass after PTCA because of suboptimal angiographic results from percutaneous transluminal coronary angioplasty. None of these stable patients died. The remainder of the patients underwent emergency coronary artery bypass after PTCA because of ongoing documented ischemia, including cardiac arrest requiring cardiopulmonary resuscitation during transit to the operating room in 11 patients (9.8%) and preoperative intra-aortic counterpulsation in 24 (21.4%). The average number of coronary arteries bypassed at emergency coronary artery bypass was 2.2, and 19 patients (17%) received at least one mammary artery conduit. The perioperative incidence of myocardial infarction was 8.9% ( 10 112 ), and the operative mortality rate 8% ( 9 112 ). During follow-up, which averaged 55 months, the survival rate (including operative mortality) was 85% while 98% of patients experienced freedom from reoperative coronary bypass, 89% experienced freedom from myocardial infarction (including postoperative) and 90% experienced freedom from subsequent catheterization or PTCA. In conclusion, emergency coronary artery bypass for PTCA complications successfully avoids subsequent untoward cardiac events. When compared with published results of PTCA without emergency coronary artery bypass, emergency coronary bypass is more reliable for avoiding subsequent cardiac catheterization (with or without PTCA) than PTCA alone.

Durability of Emergency Coronary Artery Bypass for Complications of Failed Angioplasty

Although emergency coronary artery bypass for complications of percutaneous transluminal coronary angioplasty (PTCA) has proved to be a relatively successful ‘bail-out’ procedure, little is known about the durability of revascularization under these potentially disastrous circumstances. The authors therefore retrospectively examined their results with this procedure. Emergency coronary artery bypass for complications of PTCA was performed in 112 patients between 1 January 1984 and 19 May 1992. Fifteen patients underwent PTCA for acute myocardial infarction. Eleven patients (9.8%) were stable, and underwent emergency coronary artery bypass after PTCA because of suboptimal angiographic results from percutaneous transluminal coronary angioplasty. None of these stable patients died. The remainder of the patients underwent emergency coronary artery bypass after PTCA because of ongoing documented ischemia, including cardiac arrest requiring cardiopulmonary resuscitation during transit to the operating room in 11 patients (9.8%) and preoperative intra-aortic counterpulsation in 24 (21.4%). The average number of coronary arteries bypassed at emergency coronary artery bypass was 2.2, and 19 patients (17%) received at least one mammary artery conduit. The perioperative incidence of myocardial infarction was 8.9% (10/112), and the operative mortality rate 8% (9/112). During follow-up, which averaged 55 months, the survival rate (Including operative mortality) was 85% while 98% of patients experienced freedom from reoperative coronary bypass, 89% experienced freedom from myocardial infarction (including postoperative) and 90% experienced freedom from subsequent catheterization or PTCA. In conclusion, emergency coronary artery bypass for PTCA complications successfully avoids subsequent untoward cardiac events. When compared with published results of PTCA without emergency coronary artery bypass, emergency coronary bypass is more reliable for avoiding subsequent cardiac catheterization (with or without PTCA) than PTCA alone.

Evaluation of cyropreserved internal thoracic artery as an alternative coronary graft: evidence for preserved functional, metabolic and structural integrity.

The internal thoracic artery (ITA) is the conduit of choice for coronary artery bypass grafting (CABG). This study, utilizing a canine model, evaluates cryopreserved ITA. Sixteen ITAs were harvested and cryopreserved according to United CryoInstitute protocol. Test conduits, 5 cm long and 4 mm mean diameter, were anastomosed to the ligated carotid artery of an unmatched mongrel recipient, above and below the site of native artery ligation. Graft patency was assessed by angiography at 14 days (early) and 980 days (late) postoperatively. Catheterization of the 16 vessels identified three (18%) early and one (6%) late graft occlusion. Ninety days postoperatively, each dog was killed and the graft harvested for histopathological and functional evaluation. Morphologic evaluation, using conventional staining, showed preserved cellular structure, decrease in smooth muscle cells and distorted endothelial layer. Immunocytochemistry, using an antibody against prostacyclin (PGI2), detected PGI2 immunoactivity in the ITA smooth muscle cells. An in vitro assay performed on the arterial rings confirmed preserved functional integrity of the vascular endothelium and smooth muscle. These findings suggest that cryopreserved ITA may have potential as a substitute graft, in devising conduit strategies for primary or reoperative coronary bypass surgery.

Bilateral internal mammary artery grafts in reoperative and primary coronary bypass surgery

Bilateral internal mammary artery grafting is recognized as a preferred method of myocardial revascularization. However, its efficacy in coronary bypass reoperation has not been clearly established. From January 1982 through June 1989, 88 patients underwent coronary bypass reoperation with bilateral internal mammary artery grafts. Results were compared with those for a subset of 88 patients receiving primary revascularization with bilateral internal mammary artery grafts who were computer matched for sex, age, left ventricular function, anginal classification, and left main coronary artery disease. In each group, 62.5% (55 patients) had unstable angina, 43.2% (38 patients) had reduced ejection fraction, and 21.6% (19 patients) in the reoperation group and 20.5% (18 patients) in the reference group had left main coronary artery disease. Hospital mortality for the reoperation group was 6.8% (6 patients) and for the reference group, 3.4% (3 patients). No significant difference was found in the incidence of reoperation for bleeding, sternal infection, or stroke in the two groups. The incidence of respiratory insufficiency in the reoperation group was 13.6% (12 patients) and in the reference group, 3.4% (3 patients) ( p < 0.015). Recurrent angina occurred in 13.7% (10 patients) of patients in the reoperation group and 13.3% (10 patients) in the reference group. The long-term survival at 5 years for the reoperation group was 85.3% ± 5.6% (±standard error of the mean) and for the reference group, 91.6% ± 3.1%. No significant difference was found in the equality of survival distribution for the two groups. The results of this comparative study demonstrate that bilateral internal mammary artery grafting can be accomplished with an acceptable operative risk in patients undergoing reoperation. Further, survivors of reoperation experience long-term survival benefits and functional improvement similar to those receiving primary coronary bypass surgery.