Connective tissue changes in a mouse model of vein graft disease

AIM

The extracellular matrix plays an important physiological role in the architecture of the vascular wall. In arterialized vein grafts severe early changes, such as thrombosis and neointimal hyperplasia occur. Paclitaxel is in clinical use as antiproliferative coating of coronary stents. We aimed to investigate the early connective tissue changes in arterialized vein grafts and the influence of perivascular paclitaxel treatment in an in vivo model.

METHODS

C57 black mice underwent interposition of the vena cava into the carotid artery. Neointimal hyperplasia, thrombosis, acid mucopolysaccharides (Alcian), collagen fibers (trichrome Masson), elastic fibers, and apoptosis rate (TUNEL) were quantified in paclitaxel treated veins and controls.

RESULTS

In both, controls and paclitaxel treated vein grafts acid mucopolysaccharides and elastic fibers were found predominantly in the neointima, whereas collagen fibers were found mainly in the media and adventitia. At 4 weeks postoperatively the neointimal thickness in controls was 52 (13-130) microm, whereas in 0.6 mg/mL l paclitaxel treated veins it was 103 (43-318) microm (P=0.094). At 8 weeks postoperatively paclitaxel treated veins showed a significantly increased neointimal thickness of 136 (87-199) microm compared with 79 (62-146) microm in controls (P=0.032). There was no difference in apoptosis rate between the two groups (P=NS). Even with the lowest concentration of 0.008 mg/mL paclitaxel veins showed a neointimal thickness of 67 (46-205) microm at 4 weeks postoperatively (P=NS vs controls).

CONCLUSION

Early vein graft disease is characterised by an accumulation of acid mucopolysaccharides and elastic fibers in the thickened neointima. Paclitaxel treatment increases the neointimal hyperplasia in mouse vein grafts in vivo.

Primary ovarian carcinoid heart disease curatively treated with a two-stage procedure

Primary ovarian carcinoid disease with cardiac involvement is a very rare syndrome, which requires interdisciplinary management. We report on a patient with primary ovarian carcinoid tumor with severe tricuspid valve insufficiency who was curatively treated after successful tumor resection and tricuspid valve replacement.

Treatment of double vessel coronary artery disease by totally endoscopic bypass surgery and drug-eluting stent placement in one simultaneous hybrid session

Hybrid coronary artery revascularization is a combination of minimally invasive coronary artery surgery and catheter-based coronary intervention. Hybrid procedures enable adequate revascularization of patients with multivessel coronary artery disease without complete opening of the chest and with the advantage of the most durable option, a left internal mammary artery (LIMA) graft is placed to the left anterior descending (LAD) artery. The hybrid concept is gaining renewed interest because totally endoscopic LIMA to LAD placement has become feasible and because drug-eluting stents in non-LAD targets may be competitive even for arterial bypass grafts. Simultaneous hybrid procedures would be desirable. We report on a case in which robotic totally endoscopic LIMA to LAD grafting using the da Vinci telemanipulation system was combined with placement of a rapamycin coated stent to the right coronary artery in one single procedure.

Do manual assisting maneuvers increase speed and technical performance in robotically sutured coronary bypass graft anastomoses?

BACKGROUND

Robotic endoscopic coronary artery bypass grafting procedures usually are performed as solo surgery operations. This study aimed to investigate whether manual assistance can reduce suturing times and anastomotic suturing problems in robotic coronary artery surgery.

METHODS

In isolated pig hearts, the right coronary artery was excised from the epicardium as a pedicle. This pedicled vessel, which resembles the internal mammary artery, was sutured to the left anterior descending artery using the daVinci telemanipulation system. The anastomosis was performed in a running fashion using 7/0 Pronova. In group 1 (n = 20), the suture was performed by the console surgeon as a solo operation. In group 2 (n = 20), the anastomosis was assisted by a team member using an endo forceps. The operations were performed by five surgeons of different training levels.

RESULTS

The overall anastomotic time was 24 +/- 15 min in group 1 and 22 +/- 12 min in group 2. The difference was not significant. The rate for anastomotic suturing problems (thread rupture, knot formation, sling formation, needle bending) was 8 in 20 (40%) in group 1 and 8 in 20 (40%) in group 2 (no difference). Anastomotic times and anastomotic suturing errors were dependent on surgeon experience. All anastomoses in both groups showed correct suture alignment and were probe patent.

CONCLUSION

In a wet lab model of robotic coronary anastomoses, assisting maneuvers do not decrease suturing speed. Similar suturing quality can be achieved whether the suture is performed in a solo fashion or in an assisted manner.

Placement of endovascular stent-grafts for emergency repair of acute traumatic aortic rupture: a single-centre experience

The aim of this retrospective study was to evaluate mid- and long-term results of endovascular stent-graft placement for emergency repair of acute traumatic thoracic aortic rupture. From 1996 through 2005, 22 consecutive patients (mean age: 38.7 years) underwent endovascular repair of acute traumatic thoracic aortic rupture located at the aortic isthmus in most cases. All patients were at high surgical risk due to severe associated injuries. The endografts were inserted via femoral or iliac artery access under fluoroscopic guidance. Follow-up was performed postinterventionally, at 6 and 12 months and yearly thereafter, and included clinical examination and computed tomography (CT) scans. Technical and clinical success rates were 86.3%. Mean follow-up was 31.7 months. Three patients developed early type I endoleak due to the inability of the rigid graft to adapt to the curved aortic contour. In two of them conversion to open surgery was necessary. One patient had late type I endoleak and died. No other complications were observed. The outcome was successful in most patients. The mid- and long-term results of our current study are promising. However, early type I endoleak represents a problem, especially in adolescent patients with a marked curvature of the aortic arch.

Technical challenges in totally endoscopic robotic coronary artery bypass grafting

OBJECTIVE

Robotic technology is a prerequisite for performance of totally endoscopic coronary artery bypass grafting. During the implementation phase of totally endoscopic coronary artery bypass, surgeon-related technical difficulties might be encountered. It was the aim of this study to assess the incidence of these challenges, to find risk factors, and to describe clinical results associated with technical errors.

METHODS

From October 2001 through October 2004, 40 patients received robotically assisted totally endoscopic left internal thoracic artery grafts to the left anterior descending coronary artery system with the da Vinci telemanipulation device. All patients underwent remote access cardiopulmonary bypass perfusion through groin access, and all anastomoses were performed on the arrested heart.

RESULTS

Undesirable technical events of various grades occurred in 20 (50%) of 40 patients: bleeding from a port hole in 3 (8%), left internal thoracic artery damage in 3 (8%), epicardial lesion in 3 (8%), remote access perfusion problems in 9 (23%), bleeding from the anastomosis in 4 (10%), and anastomotic stenosis in 2 (5%). There was no hospital mortality. The following differences were noted between patients without technical difficulties (group 1) and those in whom problems occurred (group 2): total operative time of 314 minutes (260-540 minutes) versus 418 minutes (270-690 minutes; P = .007), ventilation time of 6 hours (0-26 hours) versus 14 hours (0-278 hours; P = .004), intensive care unit stay of 20 hours (11-70 hours) versus 44 hours (16-336 hours; P=.183), hospital stay of 7 days (4-13 days) versus 8 days (5-21 days; P = .038), and cumulative freedom from angina at 36 months of 93% versus 100% (P = .317).

CONCLUSION

We conclude that technical difficulties during totally endoscopic coronary artery bypass grafting translate into markedly increased operative time, moderately prolonged postoperative ventilation time, and slightly increased hospital stay. Short-term survival and freedom from angina, however, do not seem to be compromised.

Factors associated with mortality and long time survival in patients undergoing modified Bentall operations

AIM

We report our results on mortality, morbidity and long time events after composite graft replacement of the aortic root and ascending aorta/aortic arch and factors associated with them.

METHODS

Seventy-four patients, aged 52 years (15-73) underwent modified ''button'' Bentall operation. The indication for operation was acute dissection in 29 (39%) patients, chronic dissection in 3 (4%), aortic regurgitation after previous replacement of the ascending aorta because of aortic dissection in 2 (3%) and non dissecting aneurysm in 40 (54%). Concommitant procedures were (partial) replacement of the aortic arch in 11 (15%) and coronary artery bypass grafting in 5 (7%). Six patients (8%) had undergone previous cardiac surgery. Mean follow up was for 49 +/- 46 months (maximum 198).

RESULTS

Length of intensive care unit (ICU) stay was 3 days (1-72). Hospital mortality was 12%. Factors significantly associated with hospital mortality were: aortic dissection, cardiopulmonary bypass time, aortic cross clamp time, deep hypothermic circulatory arrest, low cardiac output syndrome, revision due to bleeding, renal failure requiring hemofiltration, multisystemic organ failure and sepsis. None of these factors was significantly associated with long term survival. Survival rates including hospital deaths were 86%, 84%, 75% and 75% after 1, 3, 5 and 7 years respectively. Pseudoaneurysm at the composite graft occurred in 3%, infection of the prosthesis in 1%. Neither valve thrombosis nor thromboembolic events occurred postoperatively.

CONCLUSIONS

Modified Bentall operation is a demanding operation with acceptable hospital mortality. The long time survival rates are good and the big majority of patients is eventfree after operation.

Ongoing Procedure Development in Robotically Assisted Totally Endoscopic Coronary Artery Bypass Grafting (TECAB)

BACKGROUND

Totally endoscopic coronary artery bypass grafting (TECAB) using robotics requires stepwise introduction into a heart surgery program. It is the aim of this study to evaluate the state of procedure development after continued application of telemanipulation techniques in the clinical setting. We also sought to assess perioperative and intermediate term clinical results after robotically assisted CABG.

PATIENTS AND METHODS

From June 2001 to March 2005, robotically assisted CABG using the daVinci system was carried out in 107 patients with single and multi-vessel coronary artery disease. The following procedures were performed: robotically assisted endoscopic left internal mammary artery (LIMA) harvesting and completion of the procedure as conventional CABG, MIDCAB, or OPCAB (n = 22), robotically assisted suturing of LIMA-to-LAD anastomoses during conventional CABG (n = 28), TECAB on the arrested heart using remote access perfusion (n = 48), TECAB on the beating heart using an endostabilizer (n = 8), takedown of adhesions (TECAB intended) (n = 1).

RESULTS

Hospital mortality was 0% and cumulative risk adjusted mortality reached 1.6 lives saved versus EuroSCORE predictions. Undesirable surgical events (USE) such as conversion, on table revision, or postoperative revision procedures occurred in 34 out of 107 (32%) patients. Median ventilation time and ICU stay, however, were 11(0-278) hours and 21(11-389) hours, respectively. Cumulative 3 years survival was 100% and freedom from angina at 3 years was 97%.

CONCLUSIONS

We conclude that despite being surgically challenging robotically assisted coronary artery surgery can be implemented with acceptable safety. TECAB procedures have reached a reproducible state. Perioperative mortality after robotically assisted CABG may be lower than predicted. Intermediate term clinical results are very satisfactory.

Robotic totally endoscopic coronary artery bypass: program development and learning curve issues

BACKGROUND

The introduction of new procedures in heart surgery is a critical phase that includes learning curves and the risk of increased mortality or morbidity. Totally endoscopic coronary artery bypass grafting using robotic techniques represents such an innovative procedure. The aim of this report is to demonstrate the safe introduction of totally endoscopic coronary artery bypass grafting using a stepwise and modular approach.

METHODS

From June 2001 until December 2002, 50 procedures were performed using the da Vinci telemanipulator system. After baseline training the following procedure modules were carried out in a stepwise manner: robotically assisted endoscopic left internal thoracic artery harvesting and completion of the procedure as conventional coronary artery bypass grafting, minimally invasive direct coronary artery bypass, or off-pump coronary artery bypass (n = 19), robotically assisted suturing of left internal thoracic artery to left anterior descending anastomoses during conventional coronary artery bypass grafting (n = 15), totally endoscopic coronary artery bypass grafting on the arrested heart using remote access perfusion and aortic endocclusion coronary bypass grafting (n = 15). One patient was excluded intraoperatively from a robotic procedure due to pleural adhesions.

RESULTS

A significant learning curve was observed for left internal thoracic artery takedown time, y(min) = 181 - 39 x ln(x) (x = procedure number) (P <.001), and total operative time in totally endoscopic coronary artery bypass grafting, y(min) = 595 - 87 x ln(x) x = (procedure number) (P =.028). The conversion rate in totally endoscopic coronary artery bypass grafting was 2/15. Intensive care unit stay correlated significantly with total operative time (r =.427, P =.002). There was no hospital mortality.

CONCLUSION

Totally endoscopic coronary artery bypass grafting can be safely implemented into a heart surgery program. Learning curves are steep for robotic left internal thoracic artery takedown and for performance of totally endoscopic coronary artery bypass grafting. Long operative times translate into prolonged intensive care unit stay in specific cases but not into increased mortality.

A variation of the radial artery and its clinical implications for coronary artery bypass grafting

Since the radial artery is increasingly harvested as a bypass graft, surgeons are confronted with its anatomical variations. We report on a radial artery running laterally around the distal part of the radius, while a superficial palmar branch is running straight down. The radial artery can be dissected distally to get enough length for the bypass graft, but attention has to be paid to the superficial branch of the radial nerve running nearby to prevent postoperative paresthesias and numbness. The superficial palmar branch of the radial artery can be ligated. Allen's test in such a case is not valid because it is always negative.

Is the axillary artery a suitable cannulation site in aortic surgery?

AIM

The axillary artery is currently gaining interest as an alternative to femoral artery cannulation in aortic surgery. It was the aim of our study to evaluate the feasibility, safety, and efficacy of axillary artery cannulation in a series of patients undergoing surgery of the ascending aorta and/or the aortic arch.

METHODS

From 1998 to 2002 cardiopulmonary bypass (CPB) perfusion via the axillary artery was intended in 35 patients (28 male), median age 61 (22-77) years. The underlying disease was acute aortic dissection type A in 22/35 (63%), chronic aortic dissection type A in 2/35 (6%), ascending aortic aneurysm in 8/35 (22%), aortic regurgitation after previous ascending aortic replacement in 1/35 (3%), pseudoaneurysm after Bentall operation in 1/35 (3%) and coronary artery disease with severe arteriosclerosis of the aorta in 1/35 (3%).

RESULTS

Conversion to femoral artery or ascending aortic cannulation was necessary in 3 patients. In the other cases, adequate CPB flows of 2.4 l/m2/min were achieved. In 1 case local dissection of the axillary artery occurred after emergency cannulation. No postoperative complications related to axillary artery cannulation, such as upper extremity ischemia, brachial plexus injury, or local wound infection occurred. No new postoperative stroke was noted, hospital mortality was 4/35 (11%) patients.

CONCLUSION

Axillary artery cannulation is feasible in the majority of cases and seems to be a safe and effective method in surgery of the ascending aorta and aortic arch. Several disadvantages of femoral artery cannulation and perfusion can be avoided.

Extraanatomical coronary artery bypass grafts on the beating heart for management of the severely atherosclerotic ascending aorta

BACKGROUND

Crossclamping a severely atherosclerotic ascending aorta carries a significant risk of stroke in coronary artery bypass grafting. Besides other techniques aortic no touch concepts are increasingly applied for management of this problem.

METHODS

Out of 407 patients undergoing epiaortic scanning during coronary artery bypass grafting 38 (9.3%) exhibited severe ascending aortic atherosclerosis. 22 of these patients (18 male, 4 female, age 72 (57-79) years, Parsonnet Score 11 (0-18), Euro Score 8 (2-13), McSPI Stroke Risk Index 6 (1-30) %) were operated on using a beating heart and aortic no touch technique. All patients received at least one internal mammary artery (IMA) in situ graft and additional extraanatomical bypass conduits: venous Y-graft from the IMA (n=14), arterial Y-graft from the IMA (n=3), vein graft from the axillary artery (n=3), vein graft from the IMA stump (n=2), vein graft from the innominate artery (n=2).

RESULTS

No stroke occurred. The rate of perioperative myocardial infarction (CKMB rt; 50 U/l) was 5/22. Median ICU length of stay was 54 (15-1245) h. Hospital mortality was 2/22. Pre- and postoperative angina class (CCSC) were 3.3 +/- 0.9 and 1.4 +/- 0.9 respectively (p<0.001). After a median follow up period of 8 months 3 deaths, one stroke, and one myocardial infarction occurred. On 3D multislice CT scan reconstructions which were performed in 13 patients during the first postoperative year all IMA grafts to the LAD and 11 out of 13 extraanatomical vein grafts were shown to be patent.

CONCLUSION

Performance of beating heart extraanatomical coronary artery bypass grafts for management of a heavily diseased ascending aorta can result in a very low stroke rate despite a considerable stroke risk. The complexity of the procedures may be reflected by a relatively high rate of perioperative myocardial infarctions. Perioperative mortality as well as short term patency of extraanatomical bypass grafts seem to be acceptable.

Epiaortic ultrasound and intraoperative transesophageal ecocardiography for the thoracic aorta atherosclerosis assessment in patient undergoing CABG. Surgical technique modification to avoid cerebral stroke

BACKGROUND

Cerebral complication during coronary artery bypass surgery (CABG), still occurs in spite of cardiopulmonary bypass (CPB) technology advances. Our study sought to assess the role of epiaortic ultrasound (EAS) and intraoperative transesophagial ecocardiography (TEE) in detection of patients with atherosclerosis of the thoracic aorta and high risk for cerebral embolisation. Consequently our surgical strategies modification for a better cerebral protection.

METHODS

Our lot study comprise 352 patients undergoing EAS and TEE, during CABG. EAS was performed before opening of the pericardium using a 7.5 MHz ultrasonic probe packed in a sterile bag. In the presence of moderate aortic atherosclerosis (maximum aortic wall thickness of 3 mm) primarily single aortic cross-clamping and choose of aortic cannulation place was carried out. In cases of severe aortic atheroma (maximum aortic wall thickness > 5 mm or mobile plaque), aortic no touch technique, off-pump were used. From 34 patients with severe ascending aortic atherosclerosis 22 of these patients (18 male, 4 female, age 72(57-79), Parsonet Score 11(0-8), Euroscore 8(2-13), McSPI Stroke Risk Index 6 (1-30%) were managed on "no touch technique", Off-pump. All patients received at least one left internal mammary artery (LIMA) in situ graft and additional extraanatomical bypass conduits: venous Y-graft from IMA (n = 14), arterial Y-graft from LIMA (n = 3), vein graft from axillary artery (n = 3), vein graft from the RIMA stump (n = 3). Median operative time was 240 (115-435) min.

RESULTS

We found a mild aortic atherosclerosis in 151 patients (43%), moderate in 167 (47%) and severe in 34 patients (8.8%).. Operative mortality was 2/22 in a group with high risk index, from another cause than cerebral stroke. No cerebral stroke occurred. The rate of perioperative myocardial infarction (CKMB > 50U/l) was 5/22. Median stay in ICU, 54 hours (15-1245 hours). After a median follow up period of 8 months one death occurred from cerebral stroke and no myocardial infarction.

CONCLUSION

Accurate detection of atheroma on ascending aorta and aortic arch by a combination between EAS and TEE and in special surgical technique modification using off-pump revascularization and extraanatomical bypass for the management of a heavily calcified aorta can result in a very low stroke rate despite a considerable stroke risk. The hospital mortality and morbidity can be lower than predicted by Euroscore and Parsonet Score.

The axillocoronary bypass. Blood flow and short-term graft histology in a porcine model

BACKGROUND

Bypass grafts arising from the axillary artery may be indicated for complications during minimally invasive direct coronary artery bypass grafting, for redo operations and for management of a severely atherosclerotic ascending aorta. As basic data research on this technique is scanty, we investigated intraoperative function and postoperative morphology of axillocoronary bypass grafts in a porcine model.

METHODS

Thirteen German domestic pigs received an axillocoronary vein graft (Group I, n=7) or an aortocoronary vein graft (Group II, n=6) to the left anterior descending artery. In Group I the proximal anastomosis was performed to the left axillary artery, and after partial rib resection the graft was brought transpleurally to the target vessel. In both groups the coronary anastomosis was carried out on the beating heart without cardiopulmonary bypass. Graft flow was measured using transit time ultrasonic flow probes.

RESULTS

Intraoperatively all grafts showed a typical diastolic flow profile. Stable graft flow was lower in axillocoronary bypass grafts: 47 (30-60 mL/min) in Group I and 65 (35-126 mL/min) in Group II (p=0.005). Flow given as percentage of cardiac output, however, did not differ between the two grafts: 0.9 (0.6-1.2%) in Group I and 1.2 (0.8-2.4%) in Group II (p=NS). At day 4 after surgery there was no clear histologic predilection site for microtrauma and early degenerative changes in the axillocoronary graft.

CONCLUSIONS

Axillocoronary bypass flow compares well with flow in the aortocoronary graft. Microtrauma after implantation and early degenerative changes in the axillocoronary vein bypass are not particularly impacted by the thoracic entry site.

Off pump coronary artery bypass grafting in EuroSCORE high and low risk patients

OBJECTIVE

Off pump coronary artery bypass grafting (OPCAB) is claimed to reduce the operative morbidity and mortality in high risk patients. It was the aim of the study to compare the outcome of OPCAB patients classified as high- and low risk according to the EuroSCORE.

METHODS

Medical records of patients undergoing off pump coronary artery bypass grafting (n=126) at our institution between 1998 and 2001 were retrospectively reviewed. We classified them into two subgroups: low risk (EuroSCORE < or = 5, n=72, male 58 (81%), female 14 (19%), age 61 (37-78) years) and high risk (EuroSCORE >5, n=54, male 32 (59%), female 22 (41%), age 73 (42-83) years).

RESULTS

EuroSCORE high risk patients showed significantly higher rates of blood transfusion (70 vs 31%; P<0.0001), intraaortic balloon pump insertion (16 vs 3%; P=0.013), atrial fibrillation (43 vs 22%; P=0.014), and renal failure (13 vs 3%; P=0.028). ICU length of stay was significantly longer in the high risk group (25 vs 22 h; P=0.002). There was also a higher perioperative mortality in the high risk group (9 vs 0%; P=0.008).

CONCLUSION

From these data we conclude that using off pump coronary artery bypass grafting results as predicted by the EuroSCORE can be achieved. OPCAB is safe for low risk patients. Major complications seem to occur preferentially in the high risk group.

[Variability of coping strategies in coronary artery bypass surgery patients]

The state-versus-trait discussion in coping research would become more meaningful if attention is paid to the variability both of coping patterns in individual patients as well as stability of single coping strategies over time. 35 patients undergoing coronary artery bypass surgery were interviewed three times about their coping and stress experience: after cardiac catheterization, on the day before surgery, and six days after surgery. Anxiety and depression were measured. A coping attitude of "positive passivity" was present at all three points of time. While the group means were stable, vast interindividual differences occurred. Also, there was a high degree of scatter in the stability of single coping items; emotion related coping modes were more stable than cognition and action related ones. The variability of the patients' coping patterns correlated positively with the amount of stress experienced and with preoperative depression. Different coping strategies are linked to a different degree with personality traits, emotional coping modes revealing the closest connection. The variability of individual coping efforts might be linked to a personality disposition characterized by a vulnerability for stress and depressive reactions.

Minimally invasive subclavian/axillary artery to coronary artery bypass (SAXCAB): review and classification

BACKGROUND AND PURPOSE

Subclavian/axillary artery to coronary artery bypass (SAXCAB) surgery is defined as a minimally (or less) invasive coronary revascularization procedure where one or more grafts are anastomosed to the second or third parts of the subclavian artery or any of the three parts of the axillary artery (inflow source) and attached to one or more coronary arteries, and where there are two separate minimally invasive incisions to expose the target coronary artery and the inflow sources, respectively. The indications and contraindications for SAXCAB surgery are discussed, and the relevant chest wall anatomy and that of the subclavian and axillary arteries are reviewed. The effect of respiration and anatomic variability as they impact the SAXCAB graft are discussed. Three components of the anatomy that are important in SAXCAB surgery are discussed: The relation of the first rib to the clavicle insofar as it affects access to the third part of the subclavian artery, the anatomy of the subclavian and axillary arteries and their branches, and the anatomy of the chest wall and its movement. In addition, the different SAXCAB variations that have been applied clinically are reviewed and classified, and future aspects of SAXCAB research are discussed. SAXCAB surgery is unique among the different types of minimally invasive direct coronary artery bypass (MIDCAB) surgery because of the enormous diversity of the techniques that have been described. Based on these descriptions, a new classification of SAXCAB grafting is proposed depending on whether the graft is inside or outside the rib cage and whether or not the coronary artery is exposed by rib resection or through an intercostal space. The third part of the classification takes into consideration the mode of entry into the chest, whether it is by rib resection or through an intercostal space.

METHODS

Inquiries were made by telephone and by mail in the year 2000 to a number of surgeons who had published details of their SAXCAB techniques, and informal information was obtained by a series of personal communications as to the estimated number of operations they had performed and the outcomes. Published data was also used to formulate a rough guide as to the international status of the procedure at this time.

RESULTS

The total estimated international experience is about 100 cases and the patency is between 70 and 100 percent in the time frame of about one to two years.

CONCLUSIONS

The MIDCAB technique in general has been successful in providing an alternative way to revascularize the coronary arteries, and the SAXCAB has proved to be one of the most interesting classes of MIDCAB surgery. SAXCAB grafts seem to be unique among coronary revascularization procedures and, indeed, probably almost all vascular procedures, in that there is enormous diversity in the route for the graft from the inflow source to the target coronary artery. Being knowledgeable about the different varieties of SAXCAB surgeries will help the surgeon during a rescue operation as the surgery can be tailored to suit a particular patient. The SAXCAB seems to be a very safe operation, and it is striking that so far no one has reported any major complications.

Ascending aortic atherosclerosis--a complex and challenging problem for the cardiac surgeon

Ascending aortic atherosclerosis is an increasingly recognized problem in cardiac surgery. It is the most important risk factor for perioperative stroke and seems to be in part responsible for postoperative neurobehavioral changes. Patients exhibiting ascending aortic atherosclerosis have a significantly reduced survival rate and are at considerable risk for spontaneous embolic stroke during the long-term postoperative course. Preoperative noninvasive diagnosis and intraoperative assessment by inspection or palpation of the aorta are insensitive. Intraoperative epiaortic ultrasound scanning has emerged as a most helpful tool for the diagnosis of ascending aortic atherosclerosis and has revealed major insights into the nature and distribution of this disease. Management strategies range from minimally invasive aortic "no touch" techniques to maximally invasive procedures, including application of deep hypothermic circulatory arrest. Operative modifications in coronary artery bypass grafting include avoidance of aortic crossclamping, alternative methods of aortic crossclamping and placement of all arterial in situ bypass conduits, Y-grafts or extra-anatomical bypass grafts. Other operative strategies include modifications of the arterial cannulation site, replacement of the ascending aorta or ascending aortic endarterectomy. One of the most recently developed methods is embolic capture by intraaortic filters. Increased awareness of ascending aortic atherosclerosis is critical in order to prevent the devastating complications it can cause during cardiac surgery.

The subclavian and axillary arteries as inflow vessels for coronary artery bypass grafts--combined experience from three cardiac surgery centers

BACKGROUND

The subclavian and axillary arteries represent reliable inflow vessels in peripheral vascular surgery. During recent years they have also been used for special situations in coronary artery bypass grafting. We report on a preliminary, triple center experience with subclavian/axillary artery to coronary artery bypass grafting.

METHODS

Twenty-one patients (11 male, 10 female, median age 70 years) received subclavian artery/axillary artery to coronary artery bypass grafts. Indications for application of this bypass variation were internal mammary artery problems during minimally invasive coronary artery bypass grafting (n = 10), untouchable ascending aorta (n = 6), high risk reoperations (n = 3), severe chronic obstructive pulmonary disease (COPD) (n = 1) and right ventricular ischemia after ascending aortic replacement for acute aortic dissection type A (n = 1). Fourteen procedures were carried out via minithoracotomy, and seven via sternotomy. Inflow vessels were the left subclavian/axillary artery in 12 cases, the right subclavian/axillary artery in eight cases and bilateral subclavian/axillary artery in one case. Bypass conduits were the saphenous vein (n = 20 for revascularization of the left anterior descending artery, the right coronary artery and obtuse marginal branches) and the radial artery (n = 2 for revascularization of diagonal branches).

RESULTS

The procedure was without major technical problems in all patients. Hospital mortality was 1/21. Neither brachial plexus injury nor arm ischemia occurred. Mean pre- and postoperative angina classification was 3.0 +/- 0.8 and 1.2 +/- 0.4 respectively (p < 0.001). After a mean follow-up period of seven months, one out of 14 axillocoronary vein grafts studied by ultrasonic duplex scan or angiography was found occluded. Graft patency could be demonstrated for an observation period of up to two years.

CONCLUSION

Subclavian/axillary artery to coronary artery bypass is feasible and can be applied for complications in minimally invasive coronary artery bypass grafting, for redo operations and for management of the severely atherosclerotic ascending aorta. To reach the left anterior descending artery-system, the saphenous vein as well as the radial artery can be used. Complications concerning the infraclavicular incision seem to be no problem. Short-term patency rates are acceptable.

Hypoxia induces heat shock protein expression in human coronary artery bypass grafts

OBJECTIVE

Heat shock proteins (HSPs) are molecular chaperones which are essential for cell survival. Heat shock and hypoxia markedly increase the expression of several HSPs in various tissues, i.e. heart. In our in vitro study, we investigated whether HSPs are inducible in human vessels which are used as coronary artery bypass grafts.

METHODS

We used remnants of the saphenous vein and the internal mammary artery from 34 patients undergoing coronary artery bypass surgery. Each vessel was divided into segments, one for control conditions at 37 degrees C (5% CO(2)-95% air), the remaining ones for thermal (30 min at 42 degrees C) or hypoxic treatment (6 h oxygen deprivation with nitrogen). The expression of Hsp60, Hsp72 and Hsp73 was investigated by immunohistochemistry and Western-blot analysis.

RESULTS

Compared to controls, segments of the saphenous vein undergoing heat treatment showed significantly increased expression of Hsp72 in the intima (P=0.035) and Hsp73 in the media (P=0.003). In the internal mammary artery, Hsp72 and Hsp73 were expressed in the intima at significantly higher levels (P=0.042 each). A 6 h oxygen deprivation with nitrogen resulted in elevated levels of Hsp60 (media: P=0.048), of Hsp72 (intima: P<0.001 and media: P=0.004) and of Hsp73 (intima: P=0.029) in the saphenous vein. In the internal mammary artery, Hsp73 expression was significantly enhanced (intima: P=0.048 and media: P=0.017). The results were confirmed by Western-blot analysis in representative veins.

CONCLUSIONS

These findings demonstrate the common cellular defense mechanism of HSP expression in response to stress in coronary artery bypass grafts. Hypoxia and heat treatment strongly induce Hsp72 and Hsp73 expression in human coronary artery bypass grafts.

Effects of vasopressin and epinephrine on splanchnic blood flow and renal function during and after cardiopulmonary resuscitation in pigs

OBJECTIVE

To compare the effects of vasopressin versus epinephrine on splanchnic blood flow during and after cardiopulmonary resuscitation (CPR), and to evaluate the effects of these vasopressors on renal function in the postresuscitation phase.

DESIGN

Prospective, randomized laboratory investigation using an established porcine CPR model with instrumentation for continuous measurement of splanchnic and renal blood flow.

SETTING

University hospital experimental laboratory.

SUBJECTS

A total of 12 anesthetized, 12- to 16-wk-old domestic pigs weighing 30-35 kg.

INTERVENTIONS

After 4 mins of cardiac arrest, and 3 mins of CPR, 12 pigs were randomly assigned to receive either 0.4 units/kg vasopressin (n = 6) or 45 microg/kg epinephrine (n = 6). Defibrillation was performed 5 mins after drug administration; all animals were observed for 6 hrs after return of spontaneous circulation (ROSC).

MEASUREMENTS AND MAIN RESULTS

Mean +/- SEM superior mesenteric artery blood flow was significantly (p < .05) lower after vasopressin compared with epinephrine at 90 secs after drug administration (13+/-3 vs. 129+/-33 mL/min); at 5 mins after drug administration (31+/-18 vs. 155+/-39 mL/min); at 5 mins after ROSC (332+/-47 vs. 1087+/-166 mL/min); and at 15 mins after ROSC (450+/-106 vs. 1130+/-222 mL/min); respectively. Mean +/- SEM left renal and hepatic artery blood flow after ROSC was comparable in both groups ranging between 120-290 mL/min (renal blood flow), and 150-360 mL/min (hepatic blood flow), respectively. Median urine output after ROSC showed no difference between groups, and highest values (180-220 mL/hr) were observed in the first 60 mins after ROSC. Median calculated glomerular filtration rate showed no difference between groups with values ranging between 30 and 80 mL/min in the postresuscitation phase. Calculated fractional sodium excretion and osmolar relationship between urea and plasma indicated no evidence for renal tubular dysfunction.

CONCLUSIONS

In the early postresuscitation phase, superior mesenteric blood flow was temporarily impaired by vasopressin in comparison with epinephrine. With respect to renal blood flow and renal function after ROSC, there was no difference between either vasopressor given during CPR. Vasopressin given during CPR did not result in an antidiuretic state in the postresuscitation phase.

Reactive hyperemia in skin after cardiopulmonary bypass

OBJECTIVE

To study reactive hyperemia (RH) using a transcutaneous PO2/PCO2 combination electrode heated to 37 degrees C and tissue reflectance spectrophotometry in patients before and after cardiopulmonary bypass (CPB) to determine whether microcirculatory function of skin is altered.

DESIGN

Prospective study.

SETTING

Anesthesiology and critical care unit of a university hospital.

PARTICIPANTS

Eight patients undergoing elective CPB under mild hypothermia.

INTERVENTIONS

To produce RH, blood flow to the forearm was prevented by inflation of a cuff to 300 mmHg for an interval of 5 minutes.

MEASUREMENTS AND MAIN RESULTS

Measurements were obtained on the day prior to surgery (DPS), on the day of surgery (DOS) rewarmed to 37 degrees C in the intensive care unit (ICU), and on the first (POD 1) and the third postoperative days (POD 3). The following parameters were recorded: preocclusive baseline cutaneous PO2, and PCO2 (B-PtcO2, B-PtcCO2), and microvascular hemoglobin saturation (B-HbO2); postischemic peak of PtcO2, PtcCO2, and HbO2; and 10 minutes after release of the cuff occlusion posthyperemic PtcO2, PtcCO2, and HbO2. B-PtcO2 was 3.5 +/- 1.2 mmHg on DPS, 2.6 +/- 0.7 mmHg on DOS, 1.5 +/- 0.3 mmHg on POD 1, and 3.5 +/- 3.5 mmHg on POD 3. B-PtcCO2 increased significantly from 40.1 +/- 2.5 mmHg to 52.2 +/- 2.0 mmHg on DOS (p = 0.01) and to 48.9 +/- 3.6 mmHg on POD 1 (p = 0.02). On POD 3, B-PtcCO2 was 40.6 +/- 2.6 mmHg. B-HbO2 declined from a preoperative value of 42.4% +/- 8.6% to 37.1% +/- 14.7% on DOS and further to 21.7% +/- 4.8% on POD 1, which was significantly different (p = 0.03). On POD 3, B-HbO2 still remained lower (30.7% +/- 6.2%) compared with the preoperative value. RH (deltaPtcO2, deltaHBO2) was quantified as the differences between peak PtcO2, HBO2 and B-PtcO2, B-HBO2. DeltaPtcO2 was 13.0 +/- 2.3 on DPS, 11.3 +/- 2.9 on DOS, 12.6 +/- 2.6 on POD 1, and 11.5 +/- 3.5 on POD 3. DeltaHBO2 was 42.0 +/- 5.6 on DPS, 40.0 +/- 7.1 on DOS, 49.9 +/- 2.5 on POD 1, and 52.9 +/- 6.4 on POD 3. The elimination rate of carbon dioxide from skin (ECO2) was calculated as difference between peak PtcCO2 and PtcCO2 after 3 minutes of reperfusion divided by the difference between peak PtcCO2 and B-PtcCO2. ECO2 was 1.0 +/- 0.2 kPa/min on DPS, 0.7 +/- 0.1 kPa/min on DOS, and 0.8 +/- 0.1 kPa/min on POD 1 and POD 3.

CONCLUSION

Cutaneous microcirculation assessed by RH is well preserved during the immediate postoperative period in patients undergoing uncomplicated coronary artery surgery with CPB.

Natriuretic peptides stimulate cyclic guanosine monophosphate production in human saphenous vein and internal mammary artery

OBJECTIVE

It has been shown previously that the internal mammary artery releases more cyclic guanosine monophosphate after stimulation with atrial natriuretic peptide than the saphenous vein, and that C-type natriuretic peptide possesses a cyclic guanosine monophosphate stimulating potential on saphenous vein bypass grafts. The present study was undertaken to investigate intracellular content and extracellular release of cyclic guanosine monophosphate, by the internal mammary artery and saphenous vein, after challenge with further members of the natriuretic peptide family.

METHODS

Specimens of human internal mammary artery and saphenous vein from 29 patients were cut into segments and stimulated with 10(-6) M concentrations of atrial natriuretic peptide (internal mammary artery n=8, saphenous vein n=10), brain natriuretic peptide (internal mammary artery n=9, saphenous vein n=13), C-type natriuretic peptide (internal mammary artery n=12, saphenous vein n=15), and urodilatin (internal mammary artery n=8, saphenous vein n=12). Intracellular content and extracellular release of cyclic guanosine monophosphate were determined using an (125)I radioimmunoassay.

RESULTS

The following median stimulated intracellular cyclic guanosine monophosphate concentrations were measured in the internal mammary artery and saphenous vein: 35358 and 8672 fmol/cm(2) (P<0.001) after atrial natriuretic peptide, 45632 and 7830 fmol/cm(2) (P=0.003) after brain natriuretic peptide, 10144 and 13216 fmol/cm(2) (P=NS for intergraft comparison) after C-type natriuretic peptide, and 20949 and 6690 fmol/cm(2) (P=0.001) after urodilatin. Stimulation with atrial natriuretic peptide, brain natriuretic peptide and urodilation also led to a significant increase of extracellular cyclic guanosine monophosphate release by the internal mammary artery. CONCLUSIONS We conclude that brain natriuretic peptide and urodilatin exhibit a similarly effective cyclic guanosine monophosphate-stimulating potential on the internal mammary artery as atrial natriuretic peptide. In contrast, C-type natriuretic peptide shows comparable effects on the internal mammary artery and saphenous vein.

Beating heart axillocoronary bypass for management of the untouchable ascending aorta in coronary artery bypass grafting

OBJECTIVES

Cannulation and clamping of a severely atherosclerotic ascending aorta during coronary artery bypass grafting (CABG) can lead to cerebral embolization of atheromatous debris and should therefore be avoided whenever possible. A variety of surgical techniques including performance of extraanatomical coronary bypass conduits has been described to solve this problem. We report on a preliminary series of four patients in whom the axillary artery was used as an inflow vessel for venous coronary artery bypass grafts which were performed on the beating heart in order to achieve an aortic no touch concept.

METHODS

The axillary artery was exposed between the pectoralis major muscle and the deltoid muscle via an infraclavicular incision. A saphenous vein graft of at least 40 cm in length was sutured to the axillary artery and then brought into the pericardial cavity following an intercostal and transpleural route. The graft was anastomosed to the target vessel using local coronary occlusion. The procedure was carried out via sternotomy in three patients who also received additional internal mammary artery in situ grafts for adequate coronary revascularization. In one high risk patient an isolated axillocoronary bypass was performed in a minimally invasive fashion via anterolateral minithoracotomy.

RESULTS

The procedure was completed without major technical difficulties in all four patients. The mean graft length required was 33.2 +/- 1.6 cm, postoperative ultrasonic duplex scans of the axillocoronary grafts revealed a mean flow of 62.5 +/- 23.6 ml/min. No stroke or brachial plexus injury occurred. Three patients are in angina class I (Canadian Cardiovascular Society Classification), one patient is in class II postoperatively. After a mean follow-up of 11.5 +/- 6.6 months postoperatively all grafts remain patent.

CONCLUSION

Axillocoronary bypass grafting can be easily performed for management of the untouchable ascending aorta. Straightforward surgical technique and the accessibility to noninvasive diagnostics seem to offer advantages over other extraanatomical bypass grafts.