Abstract
This study was undertaken to compare early postoperative results, programmed multi-detector row computed tomography coronary angiographic patency and midterm results of revascularization by sequential radial artery grafting with those of single radial artery grafting during a five-year period. Patients were grouped as those with sequential radial artery grafts (Group A, n = 27) and single radial artery grafts (Group B, n = 26). Multi-detector row computed tomography coronary angiography was scheduled at 1 and 5 years postoperatively. Each distal anastomosis was accepted as nonfunctional if a radial artery graft was occluded proximally or there was a critical stenosis. One sequential radial artery graft and two single radial artery grafts failed in the 1-year period ( p > 0.05). In the 5-year period, three radial artery grafts failed in each group ( p > 0.05). In Group A, there was no mortality in the five-year period, but in Group B, one patient died four years after the operation due to cardiac problems ( p > 0.05). In addition to one death in Group B, there were three percutaneous interventions and two myocardial infarctions among the 26 patients during the five-year follow-up. In group A, among 27 patients, there were 4 percutaneous interventions and one myocardial infarction ( p > 0.05). Although the sample size is relatively small to be conclusive, these data suggest that sequential radial artery grafting may be considered as a method of choice for maximizing arterial graft survival and patency. Noninvasive control of sequential and single radial artery grafts with multi-detector row computed tomography is feasible with no discomfort for the patient and excellent visualization of grafts.
1
Introduction
Techniques of bypass surgery have changed through the years, with strong evidence to support the use of one or both in situ internal thoracic arteries (ITAs). Left ITA is regarded as the gold standard in coronary bypass surgery . To overcome the claimed higher failure rates of saphenous vein grafts (SVGs), surgery with all arterial grafts has been advocated whenever possible .
The radial artery (RA), which was first used by Carpentier and colleagues in 1971, was initially met with disappointing results. The use of the RA was revisited by Acar and colleagues and others who discovered the excellent late patency in a number of Carpentier and colleagues’ early series. These patients had been receiving calcium channel blockers. The RA has many desirable characteristics. It is readily available in a length suitable for bypassing most coronary lesions. It is similar in diameter to the proximal coronary arteries, marginally larger than the ITA and smaller than most SVGs. Given its ease of harvest, no additional risk of sternal wound problems and superiority to vein long-term patency, the RA has become a routinely used second arterial graft of choice in practice . The RA is ideally suited for use in sequential configuration and, consequently, it facilitates maximizing the number of constructed arterial grafts . Sequential grafting techniques have gained limited acceptance owing to technical issues, the dependence of multiple coronary beds on a single graft, and more challenging percutaneous approaches than single grafts in case of impending graft failure. Alternatively, there are intriguing data supporting improved graft patency with sequential configurations in case of saphenous vein, especially in poor run-off coronary targets .
Selective coronary angiography is an invasive procedure, with a risk of complications. Recently, with the appearance of multi-detector row computed tomography (MDCT), a noninvasive, cheaper diagnostic tool seems to be available for assessing the patency and quality of bypass grafts . In this study, our aim was to evaluate early and midterm patency rates of sequential RA grafts with the use of MDCT and compare sequential and single RA grafting techniques with respect to early and midterm survival and cardiac event free survival rates.
2
Materials and methods
2.1
Study design
This is a prospective, randomized, single-center trial, in which the patency of sequential RA grafting was compared with that of single RA grafting. Programmed coronary MDCT angiographies were performed at 1 and 5 years in all patients. This study was undertaken to compare patency of the sequential RA grafts with that of single RA grafts during first five years after surgery and to assess the survival, myocardial infarction, and reintervention rates in these two groups. The study was approved by the hospital’s ethics committee and all of the patients were informed.
Male or female patients younger than 70 years undergoing elective primary isolated coronary artery bypass surgery and requiring more than two bypass conduits were eligible for the study. All RA grafts were anastomosed to the left coronary system (diagonal artery, intermediate artery, circumflex system). An ejection fraction greater than 35% and at least two non-LAD vessels in the left coronary artery distribution with a proximal stenosis of at least 80% and a diameter of at least 1.5 mm were required. Patients with renal impairment with serum creatinine level greater than 1.5 mg/dL, lung disease with a forced expiratory volume in 1 s less than 1 L, associated major illnesses (eg, malignancy) with the survival expected to be less than 10 years, concomitant cardiac disease (such as valve disease or a left ventricular aneurysm), ascending aortic disease, chronic heart failure, emergency presentation, or myocardial infarction less than 1 week before surgery were excluded. Also redo operations, off-pump coronary artery bypass grafting surgery and minimally invasive direct coronary artery bypass procedures were exclusion criteria for this study. The RA was not harvested if the recovery time on the modified Allen test was longer than 10 s in the nondominant hand. Our plan was to evaluate these patients with MDCT instead of conventional coronary angiography. Therefore, patients with allergies to iodine contrast media, cardiac arrhythmias, tachycardia, cardiac or pulmonary failure and obesity (body mass index greater than 30 kg/m 2 ) were also excluded since these might cause poor CT image quality or CT imaging is contraindicated in these patients.
Fifty-three patients were enrolled in this study as meeting the inclusion criteria. These patients underwent CABG at our hospital between June 2004 and December 2005. All patients received an in situ left ITA graft to the LAD. The choice of the RA grafting technique was determined by computerized randomization schedule. If additional grafts were required, the SV was used. There were two groups according to the RA grafting technique. Group A (n = 27) consisted of patients receiving sequential RA grafts and group B (n = 26) patients receiving single RA grafts for the left coronary artery system. The two groups were compared with respect to preoperative demographic characteristics and risk profiles ( Table 1 ). The average age of patients was 60.5 ± 9.2 years in Group A and 58.5 ± 8.4 years in Group B. Seven patients had a previous percutaneous transluminal coronary angioplasty/stenting procedure: three patients in Group A and four patients in Group B. All of the patients were operated on electively. The two groups were comparable with respect to average age, sex, the intensity of angina pectoris, the presence of diabetes mellitus, hypertension, hypercholesterolemia, smoking history, left main coronary arterial disease, left ventricular function and previous myocardial infarction. No statistically significant difference was noted between the two groups ( Table 1 ).
| Characteristic | Group A (n = 27) | Group B (n = 26) | p Value |
|---|---|---|---|
| Age (years) | 60.5 ± 9.2 | 58.5 ± 8.4 | 0.740 |
| Male sex | 20/27 (74.1%) | 18/26 (69.2%) | 0.311 |
| Body Mass Index | 26 ± 3.7 | 27 ± 2.8 | 0.856 |
| Mean EF | 46.6 ± 8.9 | 48.3 ± 7.4 | 0.654 |
| Previous MI | 15/27 (55.6%) | 14/26 (53.8%) | 0.698 |
| USAP | 10/27 (37.0%) | 9/26 (34.6%) | 0.488 |
| Diabetes Mellitus | 8/27 (29.6%) | 10/26 (38.5%) | 0.129 |
| Hypertension | 18/27 (66.7%) | 18/26 (69.2%) | 0.537 |
| Hyperlipidemia | 11/27 (40.7%) | 12/26 (46.2%) | 0.232 |
| Smoker | 21/27 (77.8%) | 19/26 (73.1%) | 0.376 |
| LMCA disease | 4/27 (14.8%) | 5/26 (19.2%) | 0.275 |
Preoperative exclusion criteria for RA harvesting were positive Allen’s test, serum creatinine greater than 1.5 mg/dL, and significant RA stenosis as revealed by Doppler ultrasound. Prophylaxis of vasospasm was achieved by intravenous administration of calcium channel blocker (diltiazem) and nitroglycerine during the operation, as well as local spraying with diluted papaverine. The RA was preserved by covering with gauze soaked with warm papaverine solution. We preferred to use the proximal end of RA for proximal anastomosis to aorta and the distal end for distal anastomosis because of their calibers.
The suitability of a coronary artery for receiving the RA graft required fulfillment of the following criteria: Either clinical proximal stenosis (≥ 80%) or occlusion and adequate size target vessel. RA grafts were placed exclusively in the left coronary artery distribution. The inflow into the sequential RA was from the aorta. The RA grafts coursed over the surface of the heart in gentle curves without acute angulation or kinking. The side-to-side anastomoses were constructed in two ways: I. diamond configuration where the graft axis lies perpendicular to the axis of the target vessel, or II. parallel configuration where the graft and target axis are aligned. The target vessel arteriotomy length in the diamond configuration was a function of the size of the RA and was tailored to prevent a seagull deformity. All distal anastomoses were performed using either 7/0 or 8/0 polypropylene sutures and proximal anastomoses on the ascending aorta were performed using 6/0 sutures. All proximal anastomoses were performed with the aorta side clamped.
All patients were operated on pump under moderate hypothermia (32 °C) using intermittent cold blood cardioplegia followed with hotshot before aortic declamping. For a vasodilatory effect, diltiazem infusion at a dose of 1 μg/min/kg was started after the induction of anesthesia. This infusion was maintained at the same dosage for 24 h. Post-operative dilatation of RA conduit was accomplished by oral administration of 180 mg of diltiazem in 3 divided doses and they were continued for 6 months minimum with strict monitoring of blood pressure. Anticoagulation was started on postoperative day 1 with aspirin or clopidogrel in selected patients.
2.2
MDCT scanning protocol
Programmed coronary MDCT angiographies were performed at 1 and 5 years in all of the patients. Contrast-enhanced MDCT was performed by administering low osmolar nonionic high concentration contrast medium through a power injector through an 18- to 20-gauge needle inserted into an antecubital vein at a rate of 4 mL/s, followed immediately by saline flush at a rate of 4 mL/s. For optimal contrast enhancement, the scan delay was determined by the bolus-tracking technique, which positioned the region of interest in the ascending aorta. The cardiac phase with the least motion was chosen for further evaluation. Computed tomographic scans were obtained by using a 16-MDCT scanner before 2007 and a 64-MDCT scanner (Toshiba Aquilion, Toshiba Medical Systems) after 2007. After a scout image, the scan coverage was selected from the carina to the apex of the heart in the cephalic to caudal direction to include the maximum extent of the grafts. To maintain heart rate less than 60 beats/min, all patients received oral β-blockers (metoprolol succinate 50 to 100 mg/day according to body weight and basal heart rate) at least 2 to 3 days before examination and iv β-blockers (esmolol or metoprolol succinate) if oral medication was not sufficient at the examination. Images were evaluated independently by two radiologists who were aware of the previous CABG surgery type. A consensus opinion was reached among two in discordant cases. Each graft was screened separately.
2.3
Statistical analysis
Statistical analysis was performed with SPSS 15.0 (SPSS Inc., Chicago, IL, USA). Continuous variables were expressed as mean and standard deviation. Categorical variables were expressed as percentages. Dichotomous variables were analyzed using the chi-square test and Fisher’s exact test, and continuous variables were analyzed using the t test where applicable. p Values < 0.05 were considered significant.
2
Materials and methods
2.1
Study design
This is a prospective, randomized, single-center trial, in which the patency of sequential RA grafting was compared with that of single RA grafting. Programmed coronary MDCT angiographies were performed at 1 and 5 years in all patients. This study was undertaken to compare patency of the sequential RA grafts with that of single RA grafts during first five years after surgery and to assess the survival, myocardial infarction, and reintervention rates in these two groups. The study was approved by the hospital’s ethics committee and all of the patients were informed.
Male or female patients younger than 70 years undergoing elective primary isolated coronary artery bypass surgery and requiring more than two bypass conduits were eligible for the study. All RA grafts were anastomosed to the left coronary system (diagonal artery, intermediate artery, circumflex system). An ejection fraction greater than 35% and at least two non-LAD vessels in the left coronary artery distribution with a proximal stenosis of at least 80% and a diameter of at least 1.5 mm were required. Patients with renal impairment with serum creatinine level greater than 1.5 mg/dL, lung disease with a forced expiratory volume in 1 s less than 1 L, associated major illnesses (eg, malignancy) with the survival expected to be less than 10 years, concomitant cardiac disease (such as valve disease or a left ventricular aneurysm), ascending aortic disease, chronic heart failure, emergency presentation, or myocardial infarction less than 1 week before surgery were excluded. Also redo operations, off-pump coronary artery bypass grafting surgery and minimally invasive direct coronary artery bypass procedures were exclusion criteria for this study. The RA was not harvested if the recovery time on the modified Allen test was longer than 10 s in the nondominant hand. Our plan was to evaluate these patients with MDCT instead of conventional coronary angiography. Therefore, patients with allergies to iodine contrast media, cardiac arrhythmias, tachycardia, cardiac or pulmonary failure and obesity (body mass index greater than 30 kg/m 2 ) were also excluded since these might cause poor CT image quality or CT imaging is contraindicated in these patients.
Fifty-three patients were enrolled in this study as meeting the inclusion criteria. These patients underwent CABG at our hospital between June 2004 and December 2005. All patients received an in situ left ITA graft to the LAD. The choice of the RA grafting technique was determined by computerized randomization schedule. If additional grafts were required, the SV was used. There were two groups according to the RA grafting technique. Group A (n = 27) consisted of patients receiving sequential RA grafts and group B (n = 26) patients receiving single RA grafts for the left coronary artery system. The two groups were compared with respect to preoperative demographic characteristics and risk profiles ( Table 1 ). The average age of patients was 60.5 ± 9.2 years in Group A and 58.5 ± 8.4 years in Group B. Seven patients had a previous percutaneous transluminal coronary angioplasty/stenting procedure: three patients in Group A and four patients in Group B. All of the patients were operated on electively. The two groups were comparable with respect to average age, sex, the intensity of angina pectoris, the presence of diabetes mellitus, hypertension, hypercholesterolemia, smoking history, left main coronary arterial disease, left ventricular function and previous myocardial infarction. No statistically significant difference was noted between the two groups ( Table 1 ).
| Characteristic | Group A (n = 27) | Group B (n = 26) | p Value |
|---|---|---|---|
| Age (years) | 60.5 ± 9.2 | 58.5 ± 8.4 | 0.740 |
| Male sex | 20/27 (74.1%) | 18/26 (69.2%) | 0.311 |
| Body Mass Index | 26 ± 3.7 | 27 ± 2.8 | 0.856 |
| Mean EF | 46.6 ± 8.9 | 48.3 ± 7.4 | 0.654 |
| Previous MI | 15/27 (55.6%) | 14/26 (53.8%) | 0.698 |
| USAP | 10/27 (37.0%) | 9/26 (34.6%) | 0.488 |
| Diabetes Mellitus | 8/27 (29.6%) | 10/26 (38.5%) | 0.129 |
| Hypertension | 18/27 (66.7%) | 18/26 (69.2%) | 0.537 |
| Hyperlipidemia | 11/27 (40.7%) | 12/26 (46.2%) | 0.232 |
| Smoker | 21/27 (77.8%) | 19/26 (73.1%) | 0.376 |
| LMCA disease | 4/27 (14.8%) | 5/26 (19.2%) | 0.275 |
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