Clamping of the atherosclerotic ascending aorta during coronary artery bypass operations

Off-pump coronary artery bypass grafting with clampless aortic anastomosis devices: Aortic sealing devices versus automated anastomosis punching

Objectives

Clampless aortic anastomosis devices aim to lower stroke risk in off-pump coronary artery bypass grafting. Two main strategies for clampless anastomosis devices emerged with automated anastomosis punching and aortic sealing devices, prompting the question of perioperative outcome differences.

Methods

All consecutive patients undergoing elective off-pump coronary artery bypass grafting with a clampless aortic anastomosis device between September 2014 and December 2021 in 2 centers were retrospectively included. Cohorts were divided by the use of an automated anastomosis punching device or an aortic sealing device to achieve proximal anastomosis on the ascending aorta. To reach group comparability propensity score matching was performed. The primary end point was defined as a composite of all-cause mortality, stroke and rethoracotomy. Secondary end points were perioperative outcome parameters.

Results

A total of 3703 patients were enrolled of whom 575 and 3128 were included in the automated anastomosis punching and the aortic sealing device group, respectively. By propensity score matching a total of 1150 patients were included with 575 in each group. The primary composite endpoint showed no significant difference with 6.3% versus 5.9% events (odds ratio, 0.9; 95% confidence interval, 0.58-1.53, P = .81). All-cause mortality (P = .36), stroke (P = .81), and rethoracotomy (P = .89) also exhibit no disparity. Operation time was significantly longer in the aortic sealing device cohort with 220.0 ± 50.8 minutes and 204.6 ± 53.8 minutes (P < .01).

Conclusions

Clampless aortic anastomosis strategies aortic sealing device and automated anastomosis punching did not differ in perioperative outcome parameters, whereas the implementation of aortic sealing devices were associated with a prolonged operation time without inducing any inferior clinical outcome.

Synchronous versus Staged Carotid Endarterectomy and Coronary Artery Bypass Graft for Patients with Concomitant Severe Coronary and Carotid Artery Stenosis: A Systematic Review and Meta-analysis

BACKGROUND

Due to the systemic nature of atherosclerosis, arteries at different sites are commonly simultaneously affected. As a result, severe coronary artery disease (CAD) requiring coronary artery bypass grafting (CABG) frequently coexists with significant carotid stenosis that warrants revascularization. To compare simultaneous carotid endarterectomy (CEA) and CABG versus staged CEA and CABG for patients with concomitant CAD and carotid artery stenosis in terms of perioperative outcomes.

METHODS

This study was performed according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. A meta-analysis was conducted with the use of a random effects model. The I² statistic was used to assess for heterogeneity.

RESULTS

Eleven studies comprising 44,895 patients were included in this meta-analysis (21,710 in the synchronous group and 23,185 patients in the staged group). The synchronous CEA and CABG group had a statistically significant lower risk for myocardial infarction (MI) (odds ratio [OR] 0.15, 95% CI 0.04-0.61, I² = 0%) and higher risk for stroke (OR 1.51, 95% CI 1.34-1.71, I² = 0%) and death (OR 1.33, 95% CI 1.01-1.75, I² = 47.8%). Transient ischemic attacks (TIAs) (OR 1.27, 95% CI 1.00-1.61, I² = 0.0%), postoperative bleeding (OR 0.82, 95% CI 0.22-3.05, I² = 0.0%), and pulmonary complications (OR 1.52, 95% CI 0.24-9.60, I² = 67.5%) were similar between the 2 groups.

CONCLUSIONS

Patients in the simultaneous CEA and CABG group had a significantly higher risk of 30-day mortality and stroke and lower risk for MI as compared to staged CEA and CABG group. The rates of TIA, postoperative bleeding, and pulmonary complications were similar between the 2 groups. Future randomized trials or prospective cohorts are needed to validate our results.

Hand-Sewn Proximal Anastomoses in Off-Pump Coronary Artery Bypass without the Need for Partial Occlusion Clamping: Experience with the Heartstring II Proximal Seal System

Objective

To evaluate the use of the Heartstring II Proximal Seal System (HPSS) in saphenous vein to aorta anastomoses in off-pump coronary artery bypass (OPCAB).

Methods

The HPSS consists of an aortic cutter and a proximal seal system. A prospective study was done using the HPSS to facilitate proximal hand-sewn anastomoses in OPCAB without partial occlusion clamping. Intraoperative observations, including technical success and post operative clinical data, were recorded.

Results

Using the HPSS, 84 hand-sewn proximal saphenous vein–to–aorta anastomoses were done in 50 patients. In no case was conversion to partial occlusion clamping required. After deployment of the HPSS, operator evaluation showed acceptable hemostasis in 83 of the grafts. One graft required redeployment of a second HPSS. Each bypass graft was evaluated using the Medtronic Medistem Flow Probe. Acceptable flow probe values were present in all grafts, and no revisions were required. The mean length of time for completion of the proximal anastomosis was 5 minutes (range, 4 to 14 minutes). Postoperative clinical evaluation showed no adverse events attributed to the use of the HPSS.

Conclusions

The use of HPSS is a safe and effective method to avoid partial occlusion clamping in hand-sewn proximal anastomoses with OPCAB.

Hemodynamically Significant Carotid Disease and Prophylactic Carotid Endarterectomy in CABG Patients—Impact on Perioperative Neurologic Events

Perioperative neurologic deficits occur in 2-5% of patients undergoing isolated coronary artery bypass grafting (CABG). The effect of preexisting high-grade carotid artery stenosis, as determined by (1) the presence of a cervical bruit, (2) ocular plethysmog raphy (OPG), and (3) duplex scan, and the value of prophylactic carotid endarterectomy in preventing stroke, are uncertain. The hospital courses of 427 patients who underwent pre-CABG carotid duplex scan and coronary artery bypass (CAB) as the only cardiac procedure between April 1992 and June 1994 were reviewed (1) to evaluate the rela tionship between carotid stenosis and perioperative neurologic events and (2) to determine whether endarterectomy for high-grade lesions (80-99%) decreases the risk of perioperative cerebrovascular accident (CVA). There were 11 strokes (2.58%) in 427 patients, 4 CVAs occurred in 389 patients without significant carotid disease; 12 patients had total occlusion of one carotid artery and 4 of them developed a CVA (33.3%); 26 patients had a high-grade stenosis (80-99%) of one carotid artery. Twelve of these patients underwent either a pre-CABG carotid endarterectomy (CE) (5 patients) or simul taneous CE + CABG (7 patients). There were no neurologic events in this group. The 14 other patients with 80-99% stenosis did not undergo a CE. There were 3 CVAs and 1 transient ischemic attack (TIA) in this group. Seven of 11 CVAs (64%) occurred in 34 patients with either total or high-grade carotid disease (P < .0001 by Fisher Exact Test and Wilcoxin Rank Sum).

Conclusions: (1) high-grade or total occlusion of a carotid artery is associated with significantly increased risk or perioperative neurologic events. (2) Carotid endarterec tomy appears to be protective. (3) A significant number (4 of 11) of neurologic events are due to causes other than carotid stenosis.

Significance of Right Internal Thoracic Artery as Proximal Anastomotic Site

The efficacy of the right internal thoracic artery as the proximal anastomosis site in patients with a severely atherosclerotic ascending aorta was evaluated. Coronary artery bypass grafting was performed in 5 patients in whom the right internal thoracic artery was selected as the proximal anastomotic site. The graft flow in the right internal thoracic artery plus saphenous vein or radial artery graft was 52 ± 34 mL·min−1 (range, 30 to 111 mL·min−1). The right internal thoracic artery was found to supply adequate graft flow even to the sequential graft, in each patient. The right internal thoracic artery should be kept in mind when it is difficult to determine the best site for a proximal anastomosis in patients with severe atherosclerosis of the ascending aorta.

Extraanatomical coronary artery bypass grafting in patients with severely atherosclerotic (Porcelain) aorta

Background

Cannulation, cross clamping, or partial clamping of the aorta during a proximal anastomosis may cause embolic complications in patients with severely atherosclerotic (porcelain) aortas. These patients carry high morbidity and mortality risks due to intraoperative atheroembolism.

Methods

Between June 2008 and May 2010, 972 open heart surgery operations were performed in our department. In this group there were 41 patients who had severe atherosclerotic plaques in the aorta (porcelain aorta), and 9 of these underwent an extraanatomical coronary artery bypass grafting (CABG). These 9 patients were retrospectively analyzed and their demographic data, patient risk factors, and preferred surgical methods were reviewed.

Results

Seven patients underwent two-vessel CABG, while 2 underwent three-vessel CABG. Off-pump surgery was performed for 7 patients. CABG was performed with beating heart technique under cardiopulmonary bypass via femoral artery and right atrial cannulation without cross clamping in 2 of the patients. Postoperative course was uneventful in all patients. Mean length of stay in the intensive care unit was 2.11 ± 0.78 days. Mean hospitalization was 7.22 ± 0.97 days. Mean follow-up was 11.33 ± 3.67 months, and no cerebrovascular events were observed during this period. Postoperative evaluation of the grafts by multislice computed tomography revealed sufficient patency in all patients.

Conclusions

Innominate artery is an alternative inflow source for the untouchable ascending aorta caused by severe atherosclerotic disease (porcelain aorta). In this group of patients, the risk of systemic embolisation and perioperative neurologic complications can be minimized by avoiding manipulation of the ascending aorta and using the innominate artery.

Reduction of microembolic signals with a single-clamp strategy in coronary artery bypass surgery: a pilot study

BACKGROUND

Neurologic deficits are perhaps the most feared form of adverse outcome following cardiac surgery. Aortic trauma generates emboli and hence harbors the potential for neurocognitive injury. The single aortic clamp strategy of coronary artery bypass grafting (CABG) aims at reducing aortic manipulation. We hypothesized that this strategy will lead to a reduction in the number microembolic signals (MES) evaluated by transcranial Doppler (TCD), a surrogate measure of cerebral embolism.

METHODS

This pilot study was based on a prospective analysis of 22 patients in whom CABG was performed either with a single aortic clamp (SC group) or with a conventional multiple aortic side-clamp technique (MC group). The 2 groups did not differ with respect to mean age (60 + or - 6 years versus 65 + or - 8 years, not statistically significant [NS]) or EuroSCORE (2.1 + or - 1.5 versus 2.9 + or - 2, P = NS). The neurocognitive evaluation was based on the mini-mental state examination (MMSE). The preoperative MMSE values for the SC and MC groups were similar (29.5 + or - 0.5 and 29.2 + or - 1, respectively; P = NS).

RESULTS

The total number of solid-particle embolization signals secondary to aortic manipulation was lower in the SC group than in the MC group (72 + or - 28 versus 127 + or - 69, P = .02). Neurocognitive performance was moderately reduced in both groups compared with preoperative values. This reduction was more pronounced in the MC group than in the SC group (22.2 + or - 4.1 versus 25.3 + or - 1.6, P = .02). One patient in the MC group had a reversible ischemic neurologic deficit (P = NS). There were no deaths or perioperative myocardial infarctions in either group.

CONCLUSIONS

The single-clamp CABG strategy led to a reduction in MES, indicating a less pronounced embolic burden than with the conventional side-clamp CABG strategy. This strategy translated into a better performance in postoperative neurocognitive testing in the SC group of patients.

Development of a Special Balloon Occlusion Device to Prevent Adverse Events in High-Risk Patients during Open Aortic Surgery

OBJECTIVE

To prevent clamp injury that may occur during aortic surgery, we aimed to develop a special balloon occlusion (BO) device to lower the thromboembolic risk in patients with severe atherosclerosis during aortic aneurysm repair.

METHODS

The study comprised two test phases: a laboratory-testing series focussing on flexible artificial aortas, and an experimental series conducted on 10 pigs.

RESULTS

The device proved to be effective during the laboratory tests and the experiments on pigs. No complications such as intraoperative balloon rupture, dislocation, or occlusion leaks occurred. No damage to the aortic vessels was observed in further histological examinations.

CONCLUSIONS

This BO device has the potential to become an alternative to cross-clamping for vascular surgeons in patients with severely atherosclerotic vessels.

New device for saphenous vein-to-aorta proximal anastomosis without side-clamping

Background

Side clamping to perform saphenous vein-to-aorta proximal anastomosis is a well known cause of cerebral embolization during coronary bypass surgery. Automatic and manual devices have been introduced to avoid aortic clamping and facilitate proximal anastomosis but the manual ones only allow the traditional hand-sewing running suture. Nevertheless, they are not easy to use and very expensive to buy.

Methods

We developed a simple object that helps to perform a manual proximal anastomosis without the need to clamp the side of the aorta. This device is a steel bar which blocks the aortic hole and simultaneously it provides a slit to receive the needle. Through the slit comes out a thin, sharp, straight, but also well directed and predictable jet of blood which could be easily controlled during the suture.

Results

The function of the object is quite different from other devices. Nothing is deployed in the aorta. The object is only placed on the aorta with the small appendage slipped into the hole. The main advantage of the device is that while manipulation of the aorta is avoided no foreign bodies are incorporated in the suture and – most importantly – the aortic intima is not touched at all. The main drawback of the device is the blood jet coming from the slit so that the blood pressure has to be lowered by vasodilators during the anastomosis. Moreover, the suture has to change direction and the needle has to enter the aortic wall first to slip out through the slit.

Conclusion

The object was named "Slit Device" and is not a routine instrument. It would be only an alternative to other anastomotic devices with the same surgical indications. In the case of ascending aortic disease and saphenous vein grafting, the Slit Device avoids aortic clamping thereby preventing atheroembolism and also avoiding the need for hypothermic circulatory arrest in patients with unclampable aorta.

Gaseous and solid cerebral microembolization during proximal aortic anastomoses in off-pump coronary surgery: the effect of an aortic side-biting clamp and two clampless devices

OBJECTIVES

Intraoperative cerebral microembolism is a cause of cerebral dysfunction after cardiac surgery, and particulate microemboli are the most damaging. Using a new-generation transcranial Doppler ultrasound, we compared the number and nature of microemboli in patients undergoing off-pump coronary artery bypass grafting during performance of proximal anastomoses with three techniques: an aortic side-biting clamp and two clampless devices (the Enclose II device [Novare Surgical Systems, Inc, Cupertino, Calif] and the Heartstring II device [Guidant Corporation, Santa Clara, Calif]) developed to obviate the need for an aortic side-biting clamp, thereby reducing the number of cerebral microemboli.

METHODS

Bilateral continuous monitoring of the middle cerebral arteries was performed with a multirange, multifrequency transcranial Doppler device that both automatically rejects artifacts online and discriminates between solid and gaseous microemboli. Recordings were continuously undertaken during performance of 66 proximal aortic anastomoses in 42 patients. Thirty-five anastomoses were performed with an aortic side-biting clamp, 20 with the Enclose device, and 11 the Hearstring device.

RESULTS

Most microemboli occurred during application/insertion and removal of each device from the ascending aorta. The median number (interquartile range) of total microemboli was 11 (6-32) during side clamping, 11 (6-15) with the Enclose device, 40 (31-48) with the Heartstring device (P < .01). The proportion of solid microemboli was significantly higher in the side-clamp group (23%) compared with 6% and 1% in the Enclose and Heartstring groups, respectively (P < .01).

CONCLUSIONS

Avoidance of aortic side clamping results in a significant reduction in the proportion of solid microemboli detected with transcranial Doppler. As solid microemboli are probably the most damaging, use of the Enclose and Heartstring devices may represent an important strategy for minimizing cerebral injury during proximal aortic anastomoses.

First Clinical Experience With the HEARTSTRING, a Device for Proximal Anastomoses in Coronary Surgery

PURPOSE

The HEARTSTRING is a device designed to enable the creation of a clampless hand-sewn proximal anastomosis.

DESCRIPTION

Seventy-six patients who underwent myocardial revascularization had 113 proximal anastomoses created by the HEARTSTRING. Fifty-five procedures were performed on cardiopulmonary bypass and 21, off pump.

EVALUATION

Of 114 intended proximal anastomoses, 113 (99.1%) were successfully performed using the HEARTSTRING. The conduits anastomosed proximal with support of the HEARTSTRING were in 92 cases saphenous veins and in 21 cases radial arteries. Mean time to perform a HEARTSTRING-supported anastomosis was 6.6 +/- 1.2 minutes. One patient (1.3%) died postoperatively; the death was not device related. In 1 additional patient (1.3%), a stroke most likely due to air embolism occurred. Forty-nine patients (64.5%) underwent a predischarge coronary angiography (n = 20) or a contrast multislice computed tomography (n = 29). Of 76 grafts with a HEARTSTRING-supported proximal anastomosis, 74 (97.4%) were patent in these 49 patients.

CONCLUSIONS

Our initial clinical experience with the HEARTSTRING demonstrates safety, reliability, and ease of use. Side clamping of the ascending aorta can be avoided, potentially decreasing the incidence of neurologic complications.

The Impact of Aortic Manipulation on Neurologic Outcomes After Coronary Artery Bypass Surgery: A Risk-Adjusted Study

BACKGROUND

Cerebral embolization of atherosclerotic plaque debris caused by aortic manipulation during conventional coronary artery bypass grafting (CABG) is a major mechanism of postoperative cerebrovascular accidents (CVA). Off-pump CABG (OPCABG) reduces stroke rates by minimizing aortic manipulation. Consequently, the effect of different levels of aortic manipulation on neurologic outcomes after CABG surgery was examined.

METHODS

From January 1998 to June 2002, 7,272 patients underwent isolated CABG surgery through three levels of aortic manipulation: full plus tangential (side-biting) aortic clamp application (on-pump surgery; n = 4,269), only tangential aortic clamp application (OPCABG surgery; n = 2,527) or an "aortic no-touch" technique (OPCABG surgery; n = 476). A risk-adjusted logistic regression analysis was performed to establish the likelihood of postoperative stroke with each technique. Preoperative risk factors for stroke from the literature, and those found significant in a univariable model were used.

RESULTS

A significant association for postoperative stroke correspondingly increasing with the extent of aortic manipulation was demonstrated by the univariable analysis (CVA incidence respectively increasing from 0.8% to 1.6% to a maximum of 2.2%, p < 0.01). In the logistic regression model, patients who had a full and a tangential aortic clamp applied were 1.8 times more likely to have a stroke versus those without any aortic manipulation (95% confidence interval: 1.15 to 2.74, p < 0.01) and 1.7 times more likely to develop a postoperative stroke than those with only a tangential aortic clamp applied (95% confidence interval: 1.11 to 2.48, p < 0.01).

CONCLUSIONS

Aortic manipulation during CABG is a contributing mechanism for postoperative stroke. The incidence of postoperative stroke increases with increased levels of aortic manipulation.

Propensity case-matched analysis of off-pump coronary artery bypass grafting in patients with atheromatous aortic disease

OBJECTIVE

Atheromatous aortic disease is a risk factor for excessive mortality and stroke in patients undergoing coronary artery bypass grafting. Outcomes of off-pump coronary artery bypass grafting and coronary artery bypass grafting with cardiopulmonary bypass in patients with severe atheromatous aortic disease were compared by propensity case-match methods.

METHODS

Routine intraoperative transesophageal echocardiography identified 985 patients undergoing isolated coronary artery bypass grafting with severe atheromatous disease in the aortic arch or ascending aorta. Off-pump coronary artery bypass grafting was performed in 281 patients (28.5%). Propensity matched-pairs analysis was used to match patients undergoing off-pump coronary artery bypass grafting (n = 245) with patients undergoing coronary artery bypass grafting with cardiopulmonary bypass.

RESULTS

Univariate analysis revealed decreased hospital mortality (16/245, 6.5% vs 28/245, 11.4%; P =.058) and stroke prevalence (4/245, 1.6% vs 14/245, 5.7%; P =.03) in off-pump coronary artery bypass grafting compared with coronary artery bypass grafting with cardiopulmonary bypass. Freedom from any postoperative complication was higher in off-pump coronary artery bypass grafting compared with coronary artery bypass grafting with cardiopulmonary bypass (226/245, 92.2% vs 196/245, 80.0%; P <.001). Multivariable analysis of preoperative risk factors showed that increased hospital mortality was associated with coronary artery bypass grafting with cardiopulmonary bypass (odds ratio = 2.7; P =.01), fewer grafts (P =.05), acute myocardial infarction (odds ratio = 11.5; P <.001), chronic obstructive pulmonary disease (odds ratio = 2.4; P =.03), previous cardiac surgery (odds ratio = 10.2, P =.05), and peripheral vascular disease (odds ratio = 2.1; P =.05). Cardiopulmonary bypass was the only independent risk factor for stroke (odds ratio = 3.6, P =.03). At 36 months' follow-up, comparable survival was observed in the off-pump coronary artery bypass grafting and coronary artery bypass grafting with cardiopulmonary bypass groups (74% vs 72%). Multivariable analysis revealed that renal disease (P <.001), advanced age (P <.001), previous myocardial infarction (P =.03), and lower number of grafts (P =.02) were independent risks for late mortality.

CONCLUSIONS

Patients with severe atherosclerotic aortic disease who undergo off-pump coronary artery bypass grafting have a significantly lower prevalence of hospital mortality, perioperative stroke, and overall complications than matched patients who underwent coronary artery bypass grafting with cardiopulmonary bypass. Routine intraoperative transesophageal echocardiography identifies severe atheromatous aortic disease and directs the choice of surgical technique.

Strategies for the reduction of cerebral microembolism during transmyocardial laser revascularization

BACKGROUND AND OBJECTIVES

During transmyocardial laser revascularization (TMLR), multiple microembolic signals (MES) can be detected in cerebral arteries. We sought to characterize composition and clinical relevance of these MES and to evaluate strategies to reduce cerebral microembolization during TMLR.

STUDY DESIGN/MATERIALS AND METHODS

TMLR was performed in pigs. Laser energy was set to 4-10 J (group A) or 80 J (group B). Oxygen concentration was varied between 21 and 100%. MES were recorded in the ophthalmic artery. Brain and spinal cord were investigated histologically after 10 days.

RESULTS

More MES could be detected during high- compared to low-energy laser procedures. Ventilation with 100% oxygen reduced the number of MES. No lesions were found on histology.

CONCLUSIONS

The number of MES depends on the laser energy. Laser-induces cavitation-effects lead to an additional release of nitrogen bubbles. Thus, the microembolic load can be reduced by ventilation with 100% oxygen and by decreasing the laser energy.

Determination of etiologic mechanisms of strokes secondary to coronary artery bypass graft surgery

BACKGROUND AND PURPOSE

Current research focused on stroke in the setting of coronary artery bypass graft (CABG) surgery has missed important opportunities for additional understanding by failing to consider the range of different stroke mechanisms. We developed and implemented a classification system to identify the distribution and timing of stroke subtypes.

METHODS

We conducted a regional study of 388 patients with the diagnosis of stroke after isolated CABG surgery in northern New England from 1992 to 2000. Data were collected on patient and disease characteristics, intraoperative and postoperative care, and outcomes. Stroke etiology was classified into 1 of the following: hemorrhage, thromboembolic (embolic, thrombotic, lacunar), hypoperfusion, other (subtype not listed above), multiple (>or=2 competing mechanisms), or unclassified (unknown mechanism). The reliability of the classification system was determined by percent agreement and kappa statistics.

RESULTS

Embolic strokes accounted for 62.1% of strokes, followed by multiple etiologies (10.1%), hypoperfusion (8.8%), lacunar (3.1%), thrombotic (1.0%), and hemorrhage (1.0%). There were 54 strokes with unknown etiology (13.9%). There were no strokes classified as "other." Nearly 45% (105/235) of the embolic and 56% (18/32) of hypoperfusion strokes occurred within the first postoperative day.

CONCLUSIONS

We used a locally developed classification system to determine the etiologic mechanism of 388 strokes secondary to CABG surgery. The principal etiologic mechanism was embolic, followed by stroke having multiple mechanisms and hypoperfusion. Regardless of mechanism, strokes predominantly occurred within the first postoperative day.

CorLink™ sutureless aortic anastomotic device: results of an animal study

BACKGROUND

The CorLink Automated Anastomotic Device (AD) was developed to create a sutureless vein-to-aorta anastomosis without the need to clamp the aorta. This study examined the effectiveness and safety of this device in an animal model.

MATERIALS AND METHODS

Forty-seven vein-to-aorta anastomoses using the AD and 27 control hand-sutured anastomoses were constructed in 28 sheep. The distal part of these grafts were connected either to the main pulmonary artery (40 AD, 20 control), or to the sheep's brachiocephalic trunk (7 AD, 7 control). Procedural details focusing on deployment, leakage, and early patency rates were examined. Sheep were sacrificed after periods ranging from 1 to 180 days. Specimens were examined grossly and histologically.

RESULTS

All but three attempts to construct an anastomosis were successful (2 AD, 1 control). All anastomoses were patent immediately after their construction. There was no difference between control and AD anastomoses in respect to flow rates at the end of operation and before sacrifice. No metal breaks were detected. Fourteen of the 47 AD anastomoses and 6 of the control anastomoses (29.8% versus 22.2% P = ns) were occluded at autopsy. Histological findings characteristic of the healing process, were evenly distributed between AD and control anastomoses in both models. Intimal thickening was found in a notable number of anastomoses, but without any significant difference between the AD and control sutured (44.7% versus 40.7% P = ns).

CONCLUSIONS

The AD proved safe and effective for the construction of proximal vein-to-aorta anastomoses as compared to control hand-sutured anastomoses.

Single aortic clamp versus partial occluding clamp technique for cerebral protection during coronary artery bypass: a randomized prospective trial

Single aortic clamp (SAC) versus partial occluding clamp (POC) technique for the construction of proximal anastomosis has been suggested to provide better cerebral protection during coronary artery bypass grafting (CABG). The aim of this study was to assess this hypothesis in a prospective randomized trial.

METHODS

Two hundred sixty-eight consecutive patients underwent CABG at a single institution. All patients were randomized to either SAC (Group S) or POC (Group P) for the construction of the proximal anastomosis. Myocardial protection consisted of multidose antegrade cold blood cardioplegia with topical cooling. The operations were performed using standard cardiopulmonary bypass support and moderate systemic hypothermia (29 to 32 degrees C). The incidences of neurological events, perioperative myocardial infarction (MI), and mortality were prospectively evaluated.

RESULTS

The two groups were similar in mean age, gender, urgency of operation, and number of bypasses. Group S patients had a significantly longer cross-clamp (61 +/- 21 minutes [S] vs 44 +/- 13.8 minutes [P], p < 0.05) and bypass times (85 +/- 25 minutes [S] vs 74 +/- 19.7 minutes [P], p < 0.05). There were no differences in the number of perioperative MIs (Group S = 3 [2.3%]; Group P = 2 [1.5%], p = 0.50) or mortality (Group S = 2 [1.5%]; Group P = 3 [2.2%], p = 0.50). Two patients randomized to POC were switched to SAC intraoperatively because of severe calcification of the ascending aorta. In Group P, there were two strokes (1.5%) and two (1.5%) postoperative confusions versus none in Group S (relative risk = 2.0, p < 0.05, respectively).

CONCLUSION

The SAC technique improved cerebral protection without any adverse effect on myocardial protection and postoperative outcome in patients undergoing CABG.

Surgical treatment of acute arch dissection

OBJECTIVES

Acute type A arch dissections are rare and no consensus has been reached on their surgical treatment. We studied perioperative risk factors for mortality in arch dissection patients.

METHODS

Between October 1995 and October 2001, 108 patients with acute type A dissection were operated on, of whom 16 had acute arch dissections. Their mean age was 58 +/- 9 (44-77). Surgery involved total arch replacement in 4, hemiarch replacement in 10, and intimal tear repair with pledgeted sutures and ascending aortic replacement in 2.

RESULTS

One patient who underwent total arch replacement died intraoperatively due to bleeding. Both patients who underwent ascending aortic replacement and primary repair of arch tears died 2 days postoperatively, 1 due to bleeding, and the other due to multiorgan failure. In-hospital mortality was thus 18.75%, or 3 of 16. All 3 had cardiac tamponade preoperatively. The 13 survivors were discharged after a mean hospital stay of 11 +/- 6 days. Mean follow-up was 38 +/- 25 months, from 3 months to 6 years. One patient died due to graft infection 3 months postoperatively, but the remaining 12 remain in good condition. Univariate predictors of in-hospital mortality were the type of surgery (primary intimal tear repair) (p = 0.027) and preoperative cardiac tamponade (p = 0.007).

CONCLUSION

Surgical treatment of acute type A-arch dissections can be done with reasonable mortality and mid-term survival comparable with those of other subgroups with acute type A dissection. As with series of arch dissections, our patient population is too small to draw specific conclusions, but our experience leads us to conclude that the sites of intimal tears should be resected in acute type A arch dissection.

Left hemispheric strokes in coronary surgery: implications for end-hole aortic cannulas

BACKGROUND

Perioperative stroke (POS) is a devastating complication of coronary artery bypass grafting (CABG). Many studies have been published concerning risk factors and possible causes of POS but none have studied which side of the brain is more frequently involved. The finding of a strong preponderance of left-sided strokes calls into question some widely held theories as to the cause of POS and implicates end-hole aortic perfusion catheters as a major factor.

METHODS

During a 3-year period (1996 to 1998), prospective data were collected on all 2,217 consecutive CABG patients at one hospital (with surgery by different surgeons in different groups). Strokes were classified as perioperative (within 3 days of surgery) or late (beyond 3 days but during hospitalization).

RESULTS

There were a total of 51 strokes (2.3%): 21 left, 10 right, 7 bilateral, 7 lacunar, 1 brainstem, and 5 indeterminate. There were 18 major territorial perioperative strokes on the left side and 6 on the right side. Thus, 75% (18 of 24) of POS were left-sided. Stroke patients were significantly younger than nonstroke patients (66.3 +/- 10.52 versus 71.4 +/- 8.47 years, p = 0.009). Other demographic data did not differ significantly.

CONCLUSIONS

If aortic clamping, cannulation, or manipulation were responsible for most strokes, then right-sided strokes should predominate, as the innominate artery is closest to the source of such emboli. In contrast, end-hole aortic cannulas direct a high-velocity jet at the left carotid orifice and may be responsible for a large proportion of POS. Side-hole aortic cannulas may reduce the incidence of this complication.

Carotid and aortic screening for coronary artery bypass grafting

BACKGROUND

To identify risk factors for preexisting carotid and aortic disease in coronary artery bypass grafting (CABG), preoperative parameters were analyzed.

METHODS

Three-hundred eight consecutive patients undergoing elective isolated CABG were investigated through preoperative duplex scanning of the carotid artery, computed tomography of the chest, and intraoperative ultrasonography of the ascending aorta.

RESULTS

Prevalence of carotid stenosis and ascending aortic atherosclerosis was 14.3% (44 of 308) and 30.2% (93 of 308), respectively. Multivariate analysis indicated that significant independent risk factors for carotid stenosis were atherosclerosis of the ascending aorta (p = 0.028, odds ratio [OR] = 2.16), peripheral vascular disease (p = 0.008, OR = 4.08), and history of stroke (p = 0.0004, OR = 3.73). Significant independent risk factors for ascending aortic atherosclerosis were peripheral vascular disease (p = 0.029, OR = 3.05), age older than 60 years (p = 0.009, OR = 2.94), and carotid stenosis (p = 0.018, OR = 2.27). Modifications on the operative procedure for aortic atherosclerosis were carried out in 49 patients. Overall hospital mortality and morbidity for stroke were 0.97% and 0.65%, respectively.

CONCLUSIONS

Prevalence of carotid and aortic disease was not low among candidates for CABG. Carotid and aortic screening may help to modify the operative strategy to reduce morbidity of stroke.

Stroke after coronary artery bypass grafting in patients with cerebrovascular disease

BACKGROUND

Stroke has been associated with a significantly increased mortality from coronary artery bypass grafting (CABG). To determine the predictors of stroke in patients undergoing CABG, we collected data on 472 consecutive patients.

METHODS

From March 1991 to March 1999, all patients undergoing CABG at our institution underwent routine duplex scanning of the extracranial carotid and vertebral arteries. Seven patients with symptomatic carotid stenosis were treated by carotid endarterectomy (CEA) before CABG.

RESULTS

There was a 10-fold increase in mortality (12.5%) associated with postoperative stroke. Many variables were analyzed by a multivariate technique and the severity of extracranial carotid artery stenosis was determined to be the only independent predictor of postoperative stroke (p < 0.01). None of the patients with carotid artery occlusion and none of the patients who underwent CEA before CABG experienced a stroke.

CONCLUSIONS

To reduce the stroke rate, the indications for prophylactic CEA may be extended for asymptomatic patients with carotid artery stenosis greater than 75%.

The unclampable ascending aorta in coronary artery bypass patients: A surgical challenge of increasing frequency

BACKGROUND

The unclampable ascending aorta (UAA) is a condition increasingly encountered during CABG procedures. We report our experience with CABG patients with UAA and place particular emphasis on the preoperative diagnosis and surgical management.

METHODS AND RESULTS

UAA was diagnosed in 211 of 4812 consecutive CABG patients (4.3%). On the basis of the chest radiograph, echocardiogram, and coronary angiograph, a preoperative diagnosis was achieved in only 58 patients (27.4%). An age of >70 years, diabetes, smoking, unstable angina, diffuse coronaropathy, and peripheral vasculopathy were all predictors of UAA. Patients were treated with hypothermic ventricular fibrillation (no-touch technique n=129) or beating heart revascularization (no-pump technique n=82) depending on the possibility of founding an arterial cannulation site. The overall in-hospital mortality rate was 2.8% (6 of 211) with no differences between the 2 surgical strategies. The no-touch technique was associated with a greater incidence of neurological complications (stroke and transient ischemic attack), renal insufficiency, and stay in the intensive care unit and hospital. However, at midterm follow-up, more patients of the no-pump group had ischemia recurrence.

CONCLUSIONS

A preoperative diagnosis of UAA is achievable only in a minority of patients, which highlights the necessity revising the current diagnostic protocols. The use of the no-touch technique is associated with an high perioperative risk but a superior possibility of complete revascularization, whereas adoption of the no-pump strategy ensures a smoother postoperative course at the expense of an higher incidence of ischemia recurrence.

Strategy for reduction of stroke incidence in coronary bypass patients with cerebral lesions. Early results and mid-term morbidity using pulsatile perfusion

OBJECTIVES

Cerebral complication is an important factor affecting the outcome after coronary artery bypass surgery under cardiopulmonary bypass. One of the causes for cerebral complication is preoperative cerebrovascular stenotic lesion. Here, we have studied the effect of pulsatile perfusion on the rate of cerebral complication due to a cerebrovascular lesion in patients undergoing coronary arterial bypass graft under cardiopulmonary bypass.

METHODS

261 consecutive elective patients underwent operation using cardiopulmonary bypass for management of the atherosclerotic ascending aorta. Group 1 consisted of 62 patients with a cerebrovascular stenotic lesion (> or = 75%) identified on a magnetic resonance angiogram or multiple cerebral infarction diagnosed using a computer tomogram. Group 2 consisted of 199 patients diagnosed with no significant cerebral lesion. In Group 1, the systolic blood pressure during cardiopulmonary bypass was maintained at a level of 80 mmHg by means of pulsatile flow. In Group 2, non-pulsatile perfusion was used as usual.

RESULTS

The overall hospital mortality was 1.5%, and no mortality was caused by a cerebral event. Only one patient in Group 1 suffered from temporary hemiparalysis. A cerebral complication occurred in only 1.6% in Group 1, and 0.4% overall. The actuarial freedom from cerebrovascular accident after 54 months was 84.4% in Group 1, and 96.2% in Group 2 (p = 0.0011).

CONCLUSIONS

Management of the atherosclerotic ascending aorta and the use of pulsatile perfusion were helpful in preventing cerebral injury during CABG.

Retrospective analysis of cerebral complications after coronary artery bypass grafting in elderly patients

The present study retrospectively investigated cerebral complications of coronary artery bypass grafting in 205 consecutive patients aged 70 years or older, who underwent elective cardiopulmonary bypass from 1990 to 1997. Computed tomography of the brain and chest was done before surgery. Ten patients had so-called 'aortic no-touch surgery' and suffered no cerebral complications; the other 195 patients had conventional surgery. Adverse cerebral events occurred in 8.7%, including cerebral infarction (4.1%), diffuse encephalopathy (1.0%), convulsions (1.0%), transient disturbance of consciousness (1.0%), and severe loss of volition (1.5%). Multivariate analysis showed that only the detection of calcification of the ascending aorta was significantly associated with cerebral complications (p = 0.029). Total clamping tended to be superior to partial clamping for prevention of cerebrovascular accidents. The mortality rate was 7.3%. In-hospital death was related to age (p = 0.0062), cerebral complications (p = 0.0032), and a low left-ventricular function (p = 0.018). Therefore, chest computed tomography to assess the ascending aorta should be performed preoperatively. Modified techniques like aortic no-touch surgery or other therapies combined with coronary intervention may be needed in elderly patients with severe calcification of the ascending aorta.

Outcome analysis of coronary artery bypass grafting: minimally invasive versus standard techniques

Minimally invasive coronary artery bypass grafting (MIDCAB) procedures are purported to result in improvements in patient management over standard techniques. A comparative study was performed on risk-stratified patients treated with either technique. Following institutional review board approval, a retrospective random chart review was conducted on 27 MIDCAB and 37 standard coronary artery bypass grafting (CABG) patients who were operated on over a 12-month period at the University of Nebraska Medical Center. Risk stratification was accomplished by dividing the two patient populations, MIDCAB and 'standard', into one of four subgroups based on a preoperative risk score. Risk stratification was achieved by dividing the patient populations into one of four subgroups: good, fair, poor and high risk. Both groups received similar operations and surgical interventions, except for the inclusion of cardiopulmonary bypass (CPB). Approximately 200 parameters were collected and analyzed in the following categories: anthropometric, operative and postoperative outcomes. The MIDCAB group had a significantly lower number of vessels bypassed (2.0+/-0.7 vs 3.4+/-0.9, p < 0.0001). Total postoperative blood product transfusions trended higher in the standard group (6.1+/-12.6 U) when compared to the MIDCAB patients (2.3+/-5.5 U, p < 0.15), although not statistically significant. Postoperative inotrope use was significantly less in the MIDCAB group (19% vs 59%, p < 0.002). Ventilator time in the MIDCAB group was 10.5+/-5.4 h vs 15.0+/-12.3 h in the standard group (p < 0.07). The MIDCAB group had an overall greater length of stay, but was only statistically different within the poor-risk subgroup (12.2+/-10.7 vs 7.5+/-3.9, p < 0.04). The results of this study show that when CPB is not utilized in treating patients undergoing CABG procedures, the benefits in regards to patient outcomes are unclear. This necessitates the need for further work when comparing outcomes for risk-stratified patients.

Management of porcelain aorta during coronary artery bypass grafting

BACKGROUND

Patients with porcelain aorta carry a high risk of systemic embolism during coronary artery bypass grafting. No currently proposed surgical approach avoids manipulation of the heavily calcified ascending aorta. A novel surgical approach avoiding manipulation of the porcelain aorta was evaluated with regard to its efficacy in prevention of atheroemboli.

METHODS

The following surgical protocol was performed in 23 patients with porcelain aorta: (1) arterial cannulation of the axillary artery, (2) hypothermic fibrillatory arrest for performance of the distal anastomosis, and (3) construction of the proximal anastomosis to the inominate artery or to a disease-free area of the ascending aorta during hypothermic circulatory arrest.

RESULTS

The postoperative course was uneventful in all patients. No patient experienced a cerebrovascular accident or visceral organ injury as a result of atheroemboli.

CONCLUSIONS

The proposed surgical approach is safe and reliable in patients with porcelain aorta and has the potential to reduce the prevalence of stroke and systemic embolization associated with coronary artery bypass grafting in patients with porcelain aorta.

Management of coexisting coronary artery and asymptomatic carotid artery disease: report of a series of patients treated with coronary bypass alone

BACKGROUND

A retrospective chart review of 94 patients with asymptomatic high-grade carotid stenosis undergoing coronary bypass (and valve replacement in some cases) was performed to determine whether significant carotid lesions can be safely ignored in patients undergoing cardiac surgical procedures. These operations were performed during a 2-year period.

PATIENTS AND METHODS

There were 55 men and 39 women, with an age range of 37-89 years. Seventy-one patients had unilateral high-grade carotid stenosis, 17 patients had bilateral high-grade lesions, and six patients had unilateral high-grade stenosis and contralateral occlusion. Associated medical problems were recorded and short-term follow-up was obtained.

RESULTS

There was one perioperative stroke and no deaths in this group of patients.

CONCLUSIONS

Although these data indicate that high-grade carotid stenoses may be safely ignored during cardiac surgical procedures, a multicentre prospective randomized trial is needed to determine the appropriate treatment of the patient with coexisting carotid and coronary artery disease.

Cerebral injury after cardiac surgery: identification of a group at extraordinary risk. Multicenter Study of Perioperative Ischemia Research Group (McSPI) and the Ischemia Research Education Foundation (IREF) Investigators

BACKGROUND AND PURPOSE

Cerebral injury after cardiac surgery is now recognized as a serious and costly healthcare problem mandating immediate attention. To effect solution, those subgroups of patients at greatest risk must be identified, thereby allowing efficient implementation of new clinical strategies. No such subgroup has been identified; however, patients undergoing intracardiac surgery are thought to be at high risk, but comprehensive data regarding specific risk, impact on cost, and discharge disposition are not available.

METHODS

We prospectively studied 273 patients enrolled from 24 diverse US medical centers, who were undergoing intracardiac and coronary artery surgery. Patient data were collected using standardized methods and included clinical, historical, specialized testing, neurological outcome and autopsy data, and measures of resource utilization. Adverse outcomes were defined a priori and determined after database closure by a blinded independent panel. Stepwise logistic regression models were developed to estimate the relative risks associated with clinical history and intraoperative and postoperative events.

RESULTS

Adverse cerebral outcomes occurred in 16% of patients (43/273), being nearly equally divided between type I outcomes (8.4%; 5 cerebral deaths, 16 nonfatal strokes, and 2 new TIAs) and type II outcomes (7.3%; 17 new intellectual deterioration persisting at hospital discharge and 3 newly diagnosed seizures). Associated resource utilization was significantly increased--prolonging median intensive care unit stay from 3 days (no adverse cerebral outcome) to 8 days (type I; P<0.001) and from 3 to 6 days (type II; P<0.001), and increasing hospitalization by 50% (type II, P=0.04) to 100% (type I, P<0.001). Furthermore, specialized care after hospital discharge was frequently necessary in those with type I outcomes, in that only 31% returned home compared with 85% of patients without cerebral complications (P<0.001). Significant risk factors for type I outcomes related primarily to embolic phenomena, including proximal aortic atherosclerosis, intracardiac thrombus, and intermittent clamping of the aorta during surgery. For type II outcomes, risk factors again included proximal aortic atherosclerosis, as well as a preoperative history of endocarditis, alcohol abuse, perioperative dysrhythmia or poorly controlled hypertension, and the development of a low-output state after cardiopulmonary bypass.

CONCLUSIONS

These prospective multicenter findings demonstrate that patients undergoing intracardiac surgery combined with coronary revascularization are at formidable risk, in that 1 in 6 will develop cerebral complications that are frequently costly and devastating. Thus, new strategies for perioperative management--including technical and pharmacological interventions--are now mandated for this subgroup of cardiac surgery patients.

Combined carotid endarterectomy and coronary artery bypass: immediate and long-term results

Data from 213 cases of simultaneous carotid endarterectomy and coronary artery bypass grafting (CEN/CABG) were analyzed (1980-1996). There were 154 males (72.3%), and 59 females (27.7%), (mean age: 65. 6 years, range: 42-83). One hundred and thirty-two patients (62.0%) had angina, 58 (37.2%) had myocardial infarction, and 23 (10.8%) had congestive heart failure. Symptomatic cerebrovascular disease was present in 89 patients (41.7%). One hundred and twenty-two patients (57.2%) had three-vessel coronary artery disease, 41 (19.2%) had left main disease, and 27 (12.6%) had a low ejection fraction (ejection fraction </=30%). Significant (>/=75% diameter reduction) stenosis was present in 168 (78.8%) of the operated carotid arteries. The contralateral internal carotid artery was severely stenosed or occluded in 35 patients (16.4%). The hospital mortality rate was 5. 6% (12 patients). The cause of death was cardiac in ten patients (4. 6%), and neurologic in two (1%). Eleven patients (5.1%) developed a stroke postoperatively; eight strokes were ipsilateral to the operated artery, and six were permanent. Myocardial infarction occurred in five patients (2.3%). Independent predictors of early mortality were age >62 years, hypertension, and postoperative stroke (p < 0.05). Male sex was the only independent predictor of neurologic morbidity (p < 0.05). Late follow-up data were obtained for 163 (81.0%) patients (mean: 54.8 months, range: 1-168). Four (9. 3%) out of the 43 late deaths were attributed to strokes. There were three (1.8%) late ipsilateral strokes, and five (3.1%) contralateral strokes. The 5- and 10-year survival probabilities were 75 +/- 4%, and 52 +/- 6.9%. The freedom from late ipsilateral neurologic morbidity at 5 and 10 years were 97 +/- 1.7% and 90 +/- 4.0%, respectively. Taken together, the results indicate that combined carotid endarterectomy and coronary artery bypass grafting can be performed safely in this high-risk group of patients. Excellent long-term freedom from stroke can be expected.

Transmyocardial laser as an adjunct to minimally invasive CABG for complete myocardial revascularization

BACKGROUND

To achieve complete myocardial revascularization in patients with diffuse coronary artery disease and patients at high risk if they undergo cardiopulmonary bypass such as severe systemic disease or diffuse arteriosclerosis of the aorta, we have adopted the technique of combining direct coronary artery bypass grafting without cardiopulmonary bypass with transmyocardial laser revascularization.

METHODS

From April 1995 to September 1997 this technique was used in 77 patients. Ages ranged from 37 to 85 years with a mean of 56 +/- 17 years. Diffuse coronary artery lesions were present in 46 patients, 10 had severely deranged renal function, 7 had diffuse carotid artery lesions, and 7 had aortic arch atheromas. Liver dysfunction was present in 4 patients and severe obstructive airway disease in 3. The mean left ventricular ejection fraction was 0.45 +/- 0.05. Midsternotomy approach was used in 65 patients and anterior minithoracotomy in 12. Direct coronary artery bypass grafting without cardiopulmonary bypass was done to the left anterior descending coronary artery or right coronary artery or both. Transmyocardial laser revascularization using a 1,000-W CO2 laser machine was performed on the areas supplied by ungraftable coronary arteries or even in graftable distal targets in the posterolateral or inferior wall in patients who were at high risk if they underwent cardiopulmonary bypass.

RESULTS

The mean number of vessels bypassed was 1.12. One patient died of intractable ventricular arrhythmia in the early postoperative phase. Mean follow-up was 16.6 months. At 12 months 89% of the patients were angina free. Metabolic stress test demonstrated an average increase in exercise tolerance from 5.2 at baseline to 9.7 minutes at 12 months. Myocardial thallium scanning done at 3-, 6-, and 12-month intervals postoperatively revealed that myocardial perfusion in grafted segments had an exponential trend of improvement, and perfusion in transmyocardial laser revascularization segments showed a linear trend in the same period with a total gain of 28.4%.

CONCLUSIONS

Transmyocardial laser revascularization is an excellent adjunct to minimally invasive coronary artery bypass grafting to achieve complete myocardial revascularization in patients with graftable vessels in the anterior wall and ungraftable vessels in the posterior and inferior wall. This achieves complete myocardial revascularization without compromising safety in patients who are at high risk if they undergo cardiopulmonary bypass. Minimal morbidity and mortality in the present series revealed that this procedure is safe, and postoperative follow-up of these patients showed significant functional improvement as well as an improvement in myocardial perfusion scan.

Replacing the atherosclerotic ascending aorta is a high-risk procedure

BACKGROUND

Improved techniques in cerebral and myocardial protection have made replacement of the chronically aneurysmal ascending thoracic aorta a safe and effective procedure. We hypothesized that patients with severe ascending or aortic arch atherosclerosis were at greater risk for operative complications during ascending aortic replacement because of the diffuse nature of their atherosclerotic process.

METHODS

We retrospectively analyzed the records of 17 patients who received ascending aortic replacement during elective coronary artery bypass grafting (CABG) because of the intraoperative finding of severe atherosclerosis. All 17 patients underwent tube graft replacement of the ascending aorta under hypothermic circulatory arrest and retrograde cerebral perfusion before coronary artery bypass grafting. The outcomes for these patients were compared with those of a control group of 89 consecutive patients who underwent replacement for ascending thoracic aortic aneurysm.

RESULTS

The hospital mortality rate for replacement of the ascending thoracic aorta for severe atherosclerosis was 23.5% (4/17) versus 2.25% (2 of 89) for the control group (p=0.006). The incidence of cerebrovascular accident in the atherosclerotic group was 17.6% (3/17) and 3.37% (3/89) for the control group (p=0.051). Nine of 17 atherosclerotic patients (52.9%) had operative morbidity. Only 20.2% (18 of 89) of the control patients had nonfatal postoperative complications.

CONCLUSIONS

The severely atherosclerotic ascending aorta is a marker of diffuse atherosclerosis. Despite improved techniques of myocardial and cerebral protection, we have been unable to duplicate our success with ascending thoracic aneurysm repair. Preoperative screening of the ascending aorta by chest computed tomography may be appropriate in select high-risk patients to determine operability.

Prophylactic carotid endarterectomy in patients with high-grade carotid stenosis undergoing coronary bypass: does it decrease the incidence of perioperative stroke?

The etiology of perioperative stroke in patients undergoing isolated coronary artery bypass grafting (CABG) is multifactorial. One significant cause is thought to be high-grade internal carotid artery stenosis. Between April 1992 and June 1995, 1686 patients undergoing isolated CABG underwent preoperative carotid duplex scanning. This represented 77% of patients who underwent CABG during that time period (2188 patients). Sixty-eight patients (4.0%) had 80%-99% stenosis of at least one carotid artery. Fifteen patients underwent CABG without carotid intervention (Group I) and 53 patients underwent either carotid endarterectomy prior to CABG or simultaneous with CABG (Group II). Age, sex, history of prior neurologic events, ejection fraction, number of distal bypasses performed, total pump time, and aortic cross clamp times were similar between the two groups. Three patients in Group I developed a permanent postoperative neurologic deficit (20%) and one patient developed a transient deficit. The defect was focal and ipsilateral to high-grade stenosis in three patients and global in one. No patient in Group II developed either a transient or permanent neurologic deficit. There was one death in Group I in the patient who developed a global neurologic deficit and one death in Group II 2 weeks after CABG in a patient who had undergone prophylactic preCABG-carotid endarterectomy. Statistical analysis (Fisher's exact test, 2-tail) demonstrated a significant decrease both in total neurologic events (p = 0.001) and permanent neurologic defects (p = 0.005) in those patient undergoing prophylactic CE (Group II). Patients with 80%-99% carotid stenosis undergoing CEA prior to or in conjunction with isolated CABG have a decreased incidence of neurologic events postoperatively.

[Strategies for preventing stroke after coronary artery bypass grafting]

To evaluate the usefulness of our strategy for preventing stroke after CABG, 343 consecutive patients were investigated retrospectively. Patient ages ranged from 32 to 31 years (mean; 63 +/- 9 years). There were 254 males and 59 females. Number of grafts per patient was 1 to 5 (mean 2.4 +/- 0.9 grafts). In 193 patients, internal carotid arteries (ICAs) were preoperatively evaluated by duplex scanning or cerebral angiogram. The degree of atherosclerosis in the ascending aorta was preoperatively examined by plain computed tomography in 181 patients, during surgery by ultrasonography in 75 patients and palpation in all patients.

RESULTS

1. On preoperative examination, there were 26 patients (15.1%) with ICA stenosis greater than 50% and 15 patients (7.8%) with stenosis greater than 75%. Six patients had bilateral ICA stenosis or occlusion greater than 75%. In 26 patients with ICA stenosis greater than 50%, history of stroke was significantly more prevalent than that in 167 patients without ICA stenosis (12 patients: 46.2% vs 22 patients: 13.1%, p < 0.001). In patients with ICA stenosis greater than 75%, 6 patients were symptomatic and 8 were asymptomatic. For these patients, concomitant carotid endarterectomy and CABG were performed in 5, two stage procedures in 7 reconstruction of cerebral perfusion followed by CABG;4, followed by CEA: 3), and CABG alone in 3. There was no stroke in any of these patients. 2. Atherosclerosis of the ascending aorta was found in 69 of 343 patients (20.1%). In these patients, single clamp technique was applied in 50 patients, aortic no touch technique in 12 and CABG without cardiopulmonary bypass in one. The arterial cannulation site was changed to femoral artery in 15 and to axillary artery in 6 patients. Statistical analysis indicated that age (older than 60 years) and history of stroke were significant risk factors for atherosclerotic ascending aorta. 3. There were 3 patients (0.9%) with perioperative stroke caused by embolism from the ascending aorta in one and hypoperfusion of the brain during cardiopulmonary bypass in two.

CONCLUSION

Proper treatment of atherosclerotic ascending aorta and carotid occlusion may reduce the incidence of stroke in CABG patients.

Aortic atheroma is related to outcome but not numbers of emboli during coronary bypass

BACKGROUND

The relation between aortic atheroma severity and stroke after coronary artery bypass grafting is established. The relation between atheroma severity and other outcome measures or numbers of emboli has not been determined.

METHODS

Using transesophageal echocardiography, we determined the severity of atheroma in the ascending, arch, and descending aortic segments in 84 patients undergoing operations. Seventy patients were monitored using transcranial Doppler ultrasonography.

RESULTS

The incidence of stroke was 33.3% among 9 patients with mobile plaque of the arch and 2.7% among 74 patients with nonmobile plaque (p = 0.011). Cardiac complications were not significantly related to atheroma severity in any aortic segment. Length of stay was significantly related to atheroma severity in the aortic arch (p = 0.025) and descending segment (p = 0.024). The presence of severe atheroma in both the arch and descending segments was associated with significantly longer hospital stays as compared with patients with severe atheroma in neither segment (p = 0.05). Numbers of emboli were greater in patients with severe atheroma at clamp placement, although the differences did not achieve statistical significance.

CONCLUSIONS

Aortic atheroma severity is related to stroke and to the duration of hospitalization after coronary artery bypass grafting. The lack of correlation between numbers of emboli and atheroma severity suggests that m any emboli may be nonatheromatous in nature.

Adverse cerebral outcomes after coronary bypass surgery. Multicenter Study of Perioperative Ischemia Research Group and the Ischemia Research and Education Foundation Investigators

BACKGROUND

Acute changes in cerebral function after elective coronary bypass surgery is a difficult clinical problem. We carried out a multicenter study to determine the incidence and predictors of -- and the use of resources associated with -- perioperative adverse neurologic events, including cerebral injury.

METHODS

In a prospective study, we evaluated 2108 patients from 24 U.S. institutions for two general categories of neurologic outcome: type I (focal injury, or stupor or coma at discharge) and type II (deterioration in intellectual function, memory deficit, or seizures).

RESULTS

Adverse cerebral outcomes occurred in 129 patients (6.1 percent). A total of 3.1 percent had type I neurologic outcomes (8 died of cerebral injury, 55 had nonfatal strokes, 2 had transient ischemic attacks, and 1 had stupor), and 3.0 percent had type II outcomes (55 had deterioration of intellectual function and 8 had seizures). Patients with adverse cerebral outcomes had higher in-hospital mortality (21 percent of patients with type I outcomes died, vs. 10 percent of those with type II and 2 percent of those with no adverse cerebral outcome; P<0.001 for all comparisons), longer hospitalization (25 days with type I outcomes, 21 days with type II, and 10 days with no adverse outcome; P<0.001), and a higher rate of discharge to facilities for intermediate- or long-term care (69 percent, 39 percent, and 10 percent ; P<0.001). Predictors of type I outcomes were proximal aortic atherosclerosis, a history of neurologic disease, and older age; predictors of type II outcomes were older age, systolic hypertension on admission, pulmonary disease, and excessive consumption of alcohol.

CONCLUSIONS

Adverse cerebral outcomes after coronary bypass surgery are relatively common and serious; they are associated with substantial increases in mortality, length of hospitalization, and use of intermediate- or long-term care facilities. New diagnostic and therapeutic strategies must be developed to lessen such injury.

Risk factors for stroke in patients undergoing coronary artery bypass grafting

OBJECTIVE

To determine predictors of stroke in patients undergoing first-time coronary bypass grafting, we prospectively collected data on 1631 consecutive patients.

METHODS

Patients with a history of stroke and/or central nervous system symptoms (n = 134) and/or carotid bruits (n = 95) underwent carotid Doppler evaluation. Stenosis greater than 70% was considered significant. Patients with symptomatic disease or asymptomatic bilateral disease were referred for combined coronary bypass and carotid endarterectomy (n = 21). Patients with neurologic symptoms after the operation were assessed by a neurologist and underwent a computed tomographic scan. Events were classified as reversible transient ischemic attack, reversible ischemic neurologic deficit, or irreversible stroke.

RESULTS

There were 19 strokes (1.2%) and 20 deaths (1.2%) in this series. In patients with carotid screening, risk of stroke increased with severity of carotid disease and ranged from 0% in patients without stenosis, to 3.2% (1/31) in those with greater than 70% stenosis, and to 27.3% (6/22) in those with carotid occlusion. By stepwise logistic regression analysis six variables were identified as risk factors for stroke. The most important predictor was carotid occlusion with or without contralateral stenosis (odds ratio = 28, 95% confidence interval (8,105). In this group, four of five strokes occurred on the occluded side. Other risk factors were presence of ascending aortic disease at the time of surgery (odds ratio = 12.8, confidence interval 3,48), perioperative myocardial infarction (odds ratio = 8.2, confidence interval 2,33), poor left ventricular function (odds ratio = 4.6, confidence interval 1,19), peripheral vascular disease (odds ratio = 3.2, confidence interval 1,9), and age > 60 years (odds ratio = 2.9, confidence interval 0.8,11).

CONCLUSION

We conclude that risk factors for perioperative stroke in patients undergoing coronary artery bypass grafting are multiple. Carotid scanning in patients with neurologic symptoms or carotid bruits can identify patients at increased risk. Patients with carotid occlusion are at high risk for stroke on the occluded side.

High reproducibility in the interpretation of intraoperative transesophageal echocardiographic evaluation of aortic atheromatous disease

Intraoperative decisions are often based on interpretation of results from transesophageal echocardiography (TEE). One such area is the intraoperative evaluation of atheromatous disease of the thoracic aorta and subsequent classification or grading. These grading schemes are predictive of stroke after cardiac surgery. Since intraoperative strategies may be modified based on this TEE aortic atheroma grading, assessment of the interobserver variability of TEE findings between observers is essential. Forty TEE videotape segments imaging three portions of the thoracic aorta (ascending, arch, descending) were selected from 189 reports of a larger cohort. Three independent, blinded observers, experienced in TEE, evaluated these examinations for atheroma severity. If a TEE segment had insufficient data, "uninterpretable" was recorded. Weighted kappa coefficients of agreement were calculated on the three data sets. Mean weighted kappa coefficients for the three observers A, B, and C were 0.69, 0.74, and 0.72, for the ascending, arch, and descending aorta segments, respectively, representing excellent agreement. We have demonstrated uniformly high agreement for interpretation of TEE, which indicates the excellent reproducibility of TEE grading and stratification of aortic atheroma. Reproducibility within and across specialties and institutions is essential for widespread application of TEE for evaluation of the thoracic aorta.

Aortic atheromatosis and risks of cerebral embolization

With the advent of transesophageal echocardiography, aortic atheromatosis has emerged as an important source of cerebral embolization. Mobile atheromatous plaque in the ascending aorta and aortic arch has been shown to constitute a strong and independent risk factor in patients with stroke. In patients undergoing coronary bypass surgery, it is the single most important contributing factor to perioperative neurologic morbidity. Emboli originating in the heart, aorta, and proximal cerebral vasculature have been observed intraoperatively in patients undergoing coronary bypass surgery, especially when aortic clamps are released. The constitution of these emboli is unclear, although an indeterminate fraction undoubtedly represents dislodged atheromatous material. The impact of such embolization in terms of neurologic outcome is currently under investigation. Prevention of embolization from mobile aortic atheroma in patients undergoing cardiac surgery may require modification of surgical technique. Secondary prevention in patients with a history of embolization can only be determined once the natural history of such lesions is established.

Adverse neurologic events: risks of intracardiac versus extracardiac surgery

Intracardiac operations such as valve replacements have typically carried a higher risk (4.2% to 13%) of overt central nervous system outcome, compared with coronary artery bypass grafting (CABG) procedures (0.6% to 5.2%). This is likely owing to the increased risk of macroembolization of air or particulate matter from the surgical field during intracardiac surgery. The periods of highest risk for emboli are during aortic cannulation and especially during release of aortic clamps and weaning from bypass. The number of embolic events measured with transcranial Doppler is significantly higher in patients undergoing valve surgery compared with coronary surgery, particularly during cardiac ejection and immediately after bypass. However, there is current evidence that neurologic risk is increasing in patients undergoing CABG owing to the tendency to operate on older patients with more severe aortic atherosclerosis and cerebrovascular disease. Patients having an intracardiac procedure combined with a CABG procedure may be at particularly high risk for adverse neurologic outcome. For all cardiac surgical patients, there is some cause for optimism in that risk may be minimized by improved assessment (e.g., intraoperative transesophageal or epiaortic echocardiographic scanning of the ascending aorta to identify patients at risk) and monitoring (e.g., detection of embolic phenomena, using transesophageal echocardiography or transcranial Doppler technology). Furthermore, in the future, development and testing of more ideal cerebroprotective drugs may allow amelioration of neurologic injury, either by pretreating all patients at risk, or possibly even by delaying treatment until after the suspected occurrence of an insult.

Coronary artery bypass without cardiopulmonary bypass: analysis of short-term and mid-term outcome in 220 patients

Two hundred twenty patients, preferentially those with high-risk conditions, underwent coronary artery bypass grafting without cardiopulmonary bypass. Early unfavorable outcome events included operative mortality (7 patients, 3.2%), nonfatal perioperative myocardial infarction (6 patients, 2.7%), cerebrovascular accident (1 patient, 0.4%), and sternal infection (3 patients, 1.4%). There were two deaths (13%) among 15 patients with calcified aorta and four (12%) in 33 patients who underwent emergency operation. Multivariate analysis revealed these two risk factors to be the only predictors of early mortality (odds ratios, 8.0 and 9.8, respectively). Preoperative risk factors such as left ventricular dysfunction (ejection fraction < or = 35%) (40 patients, 18%), congestive heart failure (46 patients, 21%), acute myocardial infarction (59 patients, 27%), cardiogenic shock (7 patients, 3%), age 70 years or older (59 patients, 27%), renal failure (19 patients, 9%), and cerebrovascular accident and carotid disease (11 patients, 5%) were not found to be major predictors of early mortality or unfavorable outcome. During 12 months of follow-up (range 1 to 21 months), there were four cardiac and three noncardiac deaths (1-year actuarial survival 93%) and 17 cases (7.7%) of early return of angina. Calcified aorta, nonuse of the internal mammary artery, reoperation, and diabetes mellitus were independent predictors of unfavorable events. We conclude that coronary artery bypass grafting without cardiopulmonary bypass can be done with relatively low operative mortality, although there seems to be an increased risk for early return of angina. This procedure should therefore be considered for patients with appropriate coronary anatomy, in whom cardiopulmonary bypass poses a high risk. This procedure is still hazardous with calcified aorta or emergency operation.