Postoperative stroke in cardiac surgery is related to the location and extent of atherosclerotic disease in the ascending aorta

Aortic atheroma and adverse cerebral outcome: risk, diagnosis, and management options

Aortic atheromatous disease is a common finding in the patient presenting for cardiac surgery. Adverse neurologic outcome has been closely linked to the extent of aortic atherosclerosis. In order to optimize perioperative outcomes, the location and severity of disease needs accurate characterization using multimodal techniques. Although various preoperative radiographic techniques have variably identified patients with significant atheroma, intraoperative echocardiographic imaging has proven most useful in localizing and characterizing the degree of aortic atheroma. Epiaortic assessment of the ascending aorta has been utilized in guiding surgical modifications and interventions aimed at reducing the risk of neurologic injury. Although no particular technique has been definitely studied, avoidance of the identifiable atheromatous aortic region has been a main feature of the various modifications employed to optimize neurologic outcome after cardiac surgery.

Association between carotid intima-media thickness and aortic arch plaques

BACKGROUND

Large aortic arch plaques are associated with ischemic stroke. Carotid intima-media thickness (CIMT) is a marker of subclinical atherosclerosis and a strong predictor of cardiovascular disease and stroke. The association between CIMT and aortic arch plaques has been studied in patients with strokes, but not in the general population. The aim of this study was to investigate this association in an elderly asymptomatic cohort and to assess the possibility of using CIMT to predict the presence or absence of large aortic arch plaques.

METHODS

Stroke-free control subjects from the Aortic Plaque and Risk of Ischemic Stroke (APRIS) study underwent transesophageal echocardiography and high-resolution B-mode ultrasound of the carotid arteries. CIMT was measured at the common carotid artery, bifurcation, and internal carotid artery. The association between CIMT and aortic arch plaques was analyzed using multivariate regression models. The positive and negative predictive values of CIMT for large (>or=4 mm) aortic arch plaques were calculated.

RESULTS

Among 138 subjects, large aortic arch plaques were present in 35 (25.4%). Only CIMT at the bifurcation was associated with large aortic arch plaques after adjustment for atherosclerotic risk factors (P=.007). The positive and negative predictive values of CIMT for aortic arch plaque>or=4 mm at the bifurcation above the 75th percentile (>or=0.95 mm) were 42% and 80%, respectively. The negative predictive value increased to 87% when the median CIMT value (0.82 mm) was used.

CONCLUSIONS

CIMT at the bifurcation is independently associated with aortic arch plaque>or=4 mm. Its strong negative predictive value for large plaques indicates that CIMT may be used as an initial screening test to exclude severe arch atherosclerosis in the general population.

Postoperative cognitive dysfunction and aortic atheroma

BACKGROUND

The relationship of aortic atheroma to postoperative cognitive dysfunction (POCD), a common complication of coronary artery bypass graft surgery, has not been resolved. We undertook assessment of aortic atheroma using intraoperative ultrasonography and related the degree of aortic atheroma to POCD.

METHODS

Aortic atheroma was assessed using intraoperative transesophageal and epiaortic echocardiography in 311 patients who underwent coronary artery bypass graft surgery. Atheroma was graded from 0 (normal or minimal) to 3 (mobile or rough) in each of four quadrants of the proximal ascending to proximal descending thoracic aorta. Atheroma burden was defined as the atheroma score divided by the total possible score for that patient. Patients also completed a neuropsychological battery consisting of eight tests taken the week before surgery and at 1 week and 3 and 12 months afterward. Decreased cognitive function for each test was defined as an individual decrease of at least 1 standard deviation of the group baseline mean for that test, and POCD was defined as a decrease in two or more tests.

RESULTS

The atheroma burden (%) was greater in the patients with POCD. The difference was greatest at 1 week (10.4+/-14.7 versus 4.4+/-9.0, p=0.0002) and diminished progressively at 3 months (8.9+/-14.1 versus 5.4+/-10.1, p=0.06) and 12 months (6.6+/-12.0 versus 5.6+/-10.2, p=0.56). Multivariable analysis showed that atheroma burden strongly predicted POCD at 1 week.

CONCLUSIONS

Aortic atheroma burden predicts POCD at 1 week but has less impact on POCD as time progresses. Atheroma burden is highly correlated with age and may be a good predictor of early POCD.

“Beyond Beating Heart Surgery” Heartstring Device Protects against Perioperative Neurological Events

Objective

There is a growing body of evidence favoring off-pump coronary artery bypass surgery (OPCAB) over traditional coronary artery bypass surgery (CABG) with cardiopulmonary bypass as a method for reducing perioperative neurologic events. Aortic manipulation, whether with OPCAB or coronary artery bypass surgery with cardiopulmonary bypass, is strongly linked with adverse neurologic outcomes. Although the aortic “no-touch” technique has merit, most cardiac surgeons are reluctant to base entire myocardial revascularization exclusively on mammary pedicles. The purpose of this study was to analyze our experience with OPCAB combined with the use of a Heartstring proximal anastomotic device, as a strategy for reducing clinically evident cerebrovascular accidents.

Methods

Two hundred twenty-seven consecutive isolated OPCAB were performed without the use of a side-biting aortic clamp. In all these operations, a Heartstring device was used, permitting clampless hand-sutured proximal anastomoses. All patients were managed in this fashion regardless of the status of their ascending aorta. A mean of 3.4 bypasses were performed during each operation, with one or two mammary arteries harvested routinely. In 98% of patients, a single proximal anastomosis was performed; there was liberal use of sequential bypass grafts.

Results

Mean age was 69.3 years, with 17% octogenarians. Preexisting cerebrovascular disease was present in 22.4% of patients. There were no clinically evident perioperative neurologic events in any patients. There were no operative deaths.

Conclusions

This series suggests that OPCAB performed with a single, clampless, proximal aortic anastomosis, and with a Heartstring device may protect against perioperative strokes.

Comprehensive approach for clamping severely calcified ascending aorta using computed tomography

A severely calcified ascending aorta is generally considered unclampable. Many surgeons have developed procedures to avoid manipulation such as cross-clamping on such calcified aorta. However, these alternatives are sometimes complicated and require a more invasive procedure than the conventional method. We assessed our comprehensive strategy for clamping of a severely calcified aorta using preoperative computed tomography (CT). We found that the extent of calcification just below the innominate artery was significantly less than that at the usual ascending aorta clamp site. After confirming that the extent of calcification just below the innominate artery was <75% of the entire circumference by preoperative CT, ascending aorta was clamped with a soft cross-clamp placed on the ascending aorta with particular care to orientate the clamp parallel to the calcification. All operations were completed under usual cardiopulmonary bypass with mild hypothermia. All patients survived surgery and no patients had a postoperative neurological complication. Our results provide important information for the management of these high-risk patients, with a comprehensive approach used to choose the appropriate option for an optimal outcome.

Effects of poly-2-methoxyethylacrylate (PMEA)-coating on CPB circuits

OBJECTIVES

In this study, the immuno- and neuroprotective effect of a novel cardiopulmonary bypass coating was investigated.

DESIGN

Thirty nine patients scheduled for elective coronary artery bypass grafting were randomly assigned to either PMEA-coated (n = 19) or non-coated CPB circuits (n = 20). Pericardial suction blood was separated and retransfused only if needed at the end of operation. Neurocognitive functions were examined preoperatively and 7-10 days postoperatively using a standard neuropsychological test battery. Assuming an inflammatory etiology, the most cogent inflammatory markers were perioperatively analyzed.

RESULTS

Postoperatively, patients of the PMEA-coated group performed better in Go/NoGo and Mini-Mental-test than patients of the non-coated group (p < 0.04). Other neurocognitive testing did not reveal significant differences between the groups. Although most inflammatory parameters showed a significant intraindividual increase during or shortly after CPB, there was no difference in inflammatory alteration between the groups.

CONCLUSIONS

PMEA-coating of cardiopulmonary bypass surfaces revealed some minor benefits in preservation of neurocognitive functions after surgery. The immediate inflammatory response remained mostly unaffected. Suction blood separation may additionally contribute to proper postoperative outcome.

Safer aortic crossclamping during short-term moderate hypothermic circulatory arrest for cardiac surgery in patients with a bad ascending aorta

OBJECTIVE

Cardiac surgery in patients with severely atherosclerotic or porcelain ascending aorta is technically challenging, with markedly increased risk of atheroembolism. We describe a technique of meticulous crossclamping of a difficult aorta during short-term moderate hypothermic circulatory arrest.

METHODS

From 1997 to 2007, we found 40 patients (mean age, 70 +/- 8 years), including 14 patients undergoing hemodialysis, whose preoperative computed tomographic and intraoperative epiaortic ultrasonographic scans revealed eggshell calcification (n = 15) or protruding atheromas (n = 25) of the ascending aorta. They underwent cardiac surgery (aortic, 31 patients; mitral, 3 patients; both, 5 patients; and coronary alone, 1 patient) by means of meticulous crossclamping during hypothermic circulatory arrest for 3.4 +/- 1.5 minutes at a rectal temperature of 29.0 degrees C +/- 2.3 degrees C. During hypothermic circulatory arrest, we performed only internal inspection to identify the safe location of crossclamping in 21 patients, whereas we required debridement of calcification or atheroma by using the Cavitron Ultrasonic Surgical Aspirator (Tyco Healthcare, Mansfield, Mass) for safe crossclamping in 19 patients.

RESULTS

By using this technique, no patients died during the hospital stay. Stroke occurred in 1 (2.5%) patient, and transient agitation occurred in 1 patient. Re-exploration for bleeding was required in 1 patient, and wound infection occurred in 2 patients. During follow-up, with a median time of 5.2 years, the overall survival rates were 100%, 90%, and 76% at 1, 3, and 5 years, respectively. Three patients required reoperations during the follow-up period because of pseudoaneurysm in 2 patients and prosthetic valve infection in 1 patient.

CONCLUSION

Short-term moderate hypothermic circulatory arrest is quite useful for safe aortic crossclamping after internal inspection or debridement in high-risk patients with a severely atherosclerotic aorta.

An Argument for Routine Ultrasound Screening of the Thoracic Aorta in the Cardiac Surgery Population

Stroke and neurological injury are among the most devastating and disabling complications associated with cardiac surgery. Transesophageal echocardiography and epiaortic ultrasound allow for sensitive, point-of-care diagnosis of thoracic aortic disease, which is especially common in patients with heart disease. Unlike other operative procedures, the manipulation of the ascending aorta is routine in cardiac surgery and often unavoidable. Dislodgement and embolization from the ascending and aortic arch atheromas have been clearly associated with manipulation during cardiac surgery. Epiaortic ultrasound and transesophageal echocardiography screening are more accurate and more accessible to the operative team than any other available modality to diagnose atherosclerosis of the aorta. The goal of this review is to review the rationale and scientific evidence that suggests that the routine use of ultrasound guidance in cardiac surgery may improve postoperative outcomes in this patient population.

Meta-analysis of the diagnostic accuracy of transesophageal echocardiography for assessment of atherosclerosis in the ascending aorta in patients undergoing cardiac surgery

BACKGROUND

Stroke after cardiac surgery may be caused by emboli emerging from an atherosclerotic ascending aorta (AA). Epiaortic ultrasound scanning (EUS), the current 'gold' standard for detecting AA atherosclerosis, has not gained widespread use because there is a lack of optimized ultrasound devices, it lengthens the procedure, it endangers sterility, and there is a false belief by many surgeons that palpation is as sensitive as EUS. Furthermore there is no clear evidence proving that the use of epiaortic scanning changes outcome in cardiac surgery. Various researchers investigated the ability of transesophageal echocardiography (TEE) to discriminate between the presence and absence of AA atherosclerosis. It is acknowledged that TEE has limited value in this, but it has never been supported by a meta-analysis estimating the true diagnostic accuracy of TEE based on all quantitative evidence. We aimed to do this using state-of-the-art methodology of diagnostic meta-analyses.

METHODS

We searched multiple databases for studies comparing TEE vs. EUS for detection of atherosclerosis. A random-effects bivariate meta-regression model was used to obtain summary estimates of sensitivity and specificity, incorporating the correlation between sensitivity and specificity as well as covariates to explore heterogeneity across studies.

RESULTS

We extracted six studies with a total of 346 patients, of whom 419 aortic segments were analyzed, including 100 segments with atherosclerosis [median prevalence 25% (range 17-62%)]. Summary estimates of sensitivity and specificity were 21% (95% CI 13-32%) and 99% (96-99%), respectively.

CONCLUSIONS

Because of the low sensitivity of TEE for the detection of AA atherosclerosis, a negative test result requires verification by additional testing using epiaortic scanning. In case of a positive test result, AA atherosclerosis can be considered as present, and less manipulative strategies might be indicated.

Enhanced intra-operative grading of ascending aorta atheroma by epiaortic ultrasound vs echocardiography

AIMS

Intra-operative grading of atheromatous plaques in the ascending aorta by epiaortic ultrasound (EAU) and transesophageal echocardiography (TEE) in patients who have undergone CABG.

METHODS AND RESULTS

Sixty patients scheduled for elective CABG were prospectively enrolled to undergo intra-operative TEE and EAU ultrasound scanning of the ascending aorta. The ascending aorta was divided into three sections; proximal, middle and distal, and four segments; anterior, posterior, medial and lateral. Degree of atherosclerosis was graded according to a modified Montgomery scale. Epiaortic ultrasound was unable to provide images for a reliable assessment in 56 areas (7.7%; 56/720) vs 322 non-visualized areas by TEE (44.7%; 298/720) (p<0.01). Out of 563 areas that scored >or=2, EAU visualized 379/720 areas (52.6%), whereas TEE visualized 184/720 areas (25.5%) (p<0.01). EAU mean scores were significantly higher for the mid (p=0.0001) and distal (p=0.05) sections and for the posterior segment (p<0.01) vs TEE. TEE had a higher mean score than EAU in the anterior segment. When all EAU areas were grouped the posterior segment reached a significantly higher mean score (p<0.01), and the anterior segment was the second mostly diseased.

CONCLUSIONS

EAU is the intra-operative investigation of choice because it allowed a detailed grading of atheromatous lesions over the entire length of the ascending aorta. Accurate grading by TEE was restricted only to those areas that could be sufficiently visualized. TEE has a reduced power of investigation that limits its use, especially in the distal ascending aorta, a site of great surgical manipulation.

Epiaortic scanning modifies planned intraoperative surgical management but not cerebral embolic load during coronary artery bypass surgery

BACKGROUND

Patients with aortic atheroma are at increased risk for neurological injury after coronary artery bypass graft (CABG) surgery. We sought to determine the role of epiaortic ultrasound scanning for reducing cerebral embolic load, and whether its use leads to changes of planned intraoperative surgical management in patients undergoing CABG surgery.

METHODS

Patients >70-yr-of-age scheduled for CABG surgery were prospectively randomized to either an epiaortic scanning (EAS) group (aortic manipulation guided by epiaortic ultrasound) or a control group (manual aortic palpation without EAS). All patients received a comprehensive transesophageal echocardiographic examination. Transcranial Doppler (TCD) was used to monitor the middle cerebral arteries for emboli continuously from 2 min before aortic cannulation to 2 min after aortic decannulation. Neurological assessment was performed with the National Institute of Health stroke scale before surgery and at hospital discharge. The NEECHAM confusion scale was used for assessment and monitoring of patient global cognitive function on each day after surgery until hospital discharge.

RESULTS

Intraoperative surgical management was changed in 16 of 55 (29%) patients in the EAS group and in 7 of 58 (12%) patients in the control group (P = 0.025). These changes included adjustments of the ascending aorta cannulation site for cardiopulmonary bypass (CPB), the avoidance of aortic cross-clamping by using ventricular fibrillatory arrest during surgery, or by conversion to off-pump surgery. During surgery, 7 of 58 (12%) patients in the control group crossed over to the EAS group based on the results of manual aortic palpation. The median [range] TCD detected cerebral embolic count did not differ between the EAS and control groups during aortic manipulations (EAS, 11.5 [1-516] vs control, 22.0 [1-160], P = 0.91) or during CPB (EAS, 42.0 [4-516] vs control, 63.0 [5-758], P = 0.46). The NEECHAM confusion scores and National Institute of Health stroke scale scores were similar between the two groups.

CONCLUSIONS

These results show that the use of EAS led to modifications in intraoperative surgical management in almost one-third of patients undergoing CABG surgery. The use of EAS did not lead to a reduced number of TCD-detected cerebral emboli before or during CPB.

The influence of epiaortic ultrasonography on intraoperative surgical management in 6051 cardiac surgical patients

BACKGROUND

Intraoperative echocardiography has become a mainstay monitor of cardiac function and a popular diagnostic tool in patients undergoing cardiac procedures. Previous reports suggest that epiaortic ultrasonography (EU) is superior to transesophageal echocardiography and manual palpation in identifying ascending aortic atheroma. Its impact on surgical decision making has not been thoroughly investigated, however.

METHODS

We retrospectively analyzed the medical records of 6051 consecutive patients who underwent EU of their ascending aorta during cardiac operations between 1996 and 2006 to determine a potential impact on intraoperative surgical decision making. Aortic atheroma was graded according to standard classification. Neurologic complications were evaluated according to the Society of Thoracic Surgeon definition for stroke and transient ischemic attack (TIA).

RESULTS

The overall impact of EU on surgical decision making was 4.1% and included a change in the technique for inducing cardiac arrest in 1.8%, aortic atherectomy or replacement surgery in 0.8%, requirement for off-pump coronary artery bypass grafting (CABG) in 0.6%, avoidance of aortic cross-clamping and use of ventricular fibrillatory arrest in 0.5%, change in arterial cannulation site in 0.2%, or avoidance of aortic cannulation in 0.2%. The greatest affect of EU was observed in patients undergoing combined CABG with aortic/mitral valve procedures (6.7%). The smallest impact was seen in patients undergoing mitral valve operations (1.4%). Aortic atheroma was more frequent on the anterior aspect of the aorta (n = 171) in patients with a change in surgical plan than on the posterior aspect (n = 78). The overall stroke rate was lower in patients with intraoperative EU compared with all patients undergoing surgical procedures.

CONCLUSIONS

Epiaortic ultrasonography is a useful technique to detect ascending aortic atheroma, has a significant impact on surgical decision making in more than 4% of cardiac surgical patients, and might result in improved perioperative neurologic outcome.

Anaortic techniques reduce neurological morbidity after off-pump coronary artery bypass surgery

BACKGROUND

Stroke remains one of the most devastating complications of cardiac surgery. Advocates of off-pump coronary revascularisation (OPCAB) maintain that post-operative neurologic morbidity is reduced by avoiding aortic cannulation and cross-clamping, and by eliminating the systemic effects of cardiopulmonary bypass. We sought to determine whether completing off-pump coronary surgery without any aortic manipulation ("anaortic" technique) afforded any additional neurological protection, as compared to off-pump grafting in which the aorta was utilised for graft inflow.

METHODS

A comprehensive review of prospectively collected data was undertaken of all patients undergoing OPCAB in our institution between January 2002 and December 2006. Cases requiring intra-operative conversion to cardiopulmonary bypass were excluded from further analysis. Patients having OPCAB surgery with aortic manipulation were compared to those having OPCAB surgery without aortic manipulation. Multiple logistic regression was used to identify possible predictors of post-operative neurologic morbidity, with particular focus on the role of aortic manipulation.

RESULTS

During the period of review, 1758 patients underwent OPCAB, of which 1201 (68.3%) were completed without aortic manipulation, constituting the "anaortic" cohort. This group was compared with the remaining 557 patients, which included fashioning at least one aorto-conduit anastomosis, utilising either a side-biting aortic clamp or a no-clamp proximal anastomotic device. The two groups of patients were well-matched with respect to risk factors for adverse neurologic outcomes. Nine patients sustained focal neurological deficits (transient or permanent) in the peri-operative period, constituting a stroke rate of 0.51% for the entire series. The incidence of peri-operative neurological deficit in the anaortic group was 0.25% compared with 1.1% in the aortic manipulation group (odds ratio (OR) 0.23, 95% confidence interval (CI) 0.06-0.92, p=0.037). Advanced age was also associated with peri-operative neurological injury (OR 1.1, 95% CI 1.01-1.20, p=0.017).

CONCLUSIONS

Off-pump coronary artery surgery is associated with a low incidence of peri-operative stroke. Completing the surgical procedure without manipulating the ascending aorta in any way ("anaortic" technique) offers additional neurological protection and should be the goal in all suitable off-pump coronary cases.

Surgical treatment of heart failure in the elderly

Heart failure (HF) in elderly patients who may benefit from surgical therapy is usually secondary to ischemic or valvular heart disease. When referring such patients for surgery, life expectancy, along with the expectations of the patient and family with regard to the surgical treatment, must be considered. The goals of cardiac surgery in this patient population are to maintain or improve cardiac function, decrease HF episodes, reduce hospital admissions, and improve functional class. Safer surgical techniques developed during the last two decades have allowed high-risk patients well into their 80s to undergo complex cardiac operations with decreasing morbidity and mortality. Successful surgical intervention often leads to a more productive and independent life for elderly patients who have HF.

Risk factors for perioperative stroke after thoracic endovascular aortic repair

BACKGROUND

Stroke has emerged as an important complication of thoracic endovascular aortic repair (TEVAR). Identifying risk factors for stroke is important to define the risks of this procedure.

METHODS

All neurologic complications were analyzed in a prospective database of patients in thoracic aortic stent graft trials from 1999 to 2006. Serial neurological examination was performed. Stroke was defined as any new onset focal neurologic deficit.

RESULTS

The TEVAR was performed on 171 patients; 52 had lesions requiring coverage of the proximal descending thoracic aorta (extent A), 50 requiring coverage of the distal descending aorta (extent B), and 69 requiring coverage of the entire descending thoracic aorta (extent C). The incidence of stroke was 5.8%. Eighty-nine percent (8 of 9) of strokes occurred within 24 hours of operation. Stroke was associated with a 33% in-hospital mortality rate. Risk factors identified for stroke included prior stroke (odds ratio [OR] 9.4, confidence interval [CI] 2.3 to 38.1, p = 0.002) and extent A or C coverage (OR 5.5, CI 1.7-12.5, p = 0.001). The stroke rate in patients with both prior stroke and extent A or C coverage was 27.7%. Severe atheromatous disease involving the aortic arch by computed tomographic scan was strongly associated with perioperative stroke (OR = 14.8, CI 1.7 to 675.6, p = 0.0016). Transesophageal echocardiography demonstrated mobile atheroma in two patients with stroke.

CONCLUSIONS

Stroke after TEVAR was associated with a high mortality. The TEVAR of the proximal descending aorta (extent A or C) in patients with a history of stroke had the highest perioperative stroke rate. These risk factors, together with high grade aortic atheroma of the aortic arch, predicted a high probability for cerebral embolization and can be used to identify patients at high risk for stroke as a consequence of TEVAR.

Excellent Results of Contemporary Coronary Artery Bypass Grafting with Systematic Application of Modern Perioperative Strategies

BACKGROUND

The patient population referred for coronary artery bypass grafting (CABG) has become more challenging. The surgical population is aging and patients present with significant preoperative comorbidities. This worsening risk profile has led to the development of operative techniques (off-pump CABG) and perioperative measures (epi-aortic scanning, intensive insulin therapy) to preserve the quality of care following CABG. The aim of this study was to determine the outcome of contemporary CABG following the implementation of the above measures in our practice.

METHODS

We retrospectively analyzed prospectively collected data of 2725 patients undergoing CABG between 01/1998 and 12/2005 (mean age, 65 +/- 11 years; 843 [31%] female; mean ejection fraction, 45% +/- 14%). Outcome measures included hospital mortality, postoperative complications, and long-term survival and independent predictors of outcome. Subgroup analyses were performed for 2 study periods (1998-2002 versus 2003-2005) where the above measures were implemented and for patients undergoing conventional versus off-pump CABG.

RESULTS

When comparing the 2 study periods, we observed a substantial worsening of the risk profile with an increased EuroSCORE predicted mortality from 6.4% +/- 6.8% to 7.0% +/- 7.8% (P = .028). During the same period, operative mortality decreased from 2.4% to 0.7% (P < .001). This reduction in mortality was also observed in diabetic patients (3.1% versus 1.0%, P = .021) and those with low ejection fraction (4% versus 2.6%, P = not significant). Off-pump procedures were performed with an increasing frequency in high-risk patients in whom we obtained excellent results. Finally, we observed a reduction of postoperative complications including respiratory failure (P = .013), gastrointestinal complications (P = .017), and stroke (P = .094). Independent predictors of mortality included renal failure (OR = 5.7), peripheral vascular disease (OR = 2.9), intra-aortic balloon pump (OR = 4.8), reoperation (OR = 3.3), and hypertension (OR = 2.3).

CONCLUSION

Despite a worsening case mix, contemporary CABG can be performed with excellent results (operative mortality < 1%). Off-pump CABG performed in very high-risk patients obtains results similar to those of the general CABG population. Diabetes and ejection fraction were not independent predictors of early outcome. In our experience, these excellent outcomes were achieved by adopting an operative approach using modern perioperative management (epi-aortic scanning, intensive insulin therapy) and surgical techniques (off-pump CABG) based on individual patients.

Preoperative noncontrast chest computed tomography identifies potential aortic emboli

BACKGROUND

Intraoperative epiaortic scanning identifies aortic atheroma. Avoiding atheroma manipulation reduces cerebral vascular accidents (CVA). Unfortunately, epiaortic scanning can only be performed after the time of sternotomy. We sought to determine whether (1) preoperative noncontrast chest computed tomography (CT) identifies areas of aorta at risk for embolization in high-risk patients, and (2) operative strategies designed at the reduction of aortic manipulation of these areas can reduce permanent strokes.

METHODS

The rate of permanent strokes was examined at a single institution between two time periods using the chi2 method. From January 2002 through June 2003 (pre-CT) 230 patients underwent elective cardiac procedures. All patients received routine intraoperative transesophageal echocardiography but only selective epiaortic scanning. From July 2003 through December 2005 (post-CT), 273 patients underwent cardiac operations and 114 patients at high risk for a stroke (history of CVA or transient ischemic attack, peripheral vascular disease, end-stage renal disease, age >70 years old or calcifications on cardiac catheterization) also received a preoperative noncontrast chest CT.

RESULTS

In the pre-CT period, 7 patients received epiaortic scans that resulted in a change in operative strategy in only 1 patient. In the post-CT period, the 114 CT scans identified 20 patients with significant calcifications in the ascending aorta. Operative strategy was altered in 19 patients, including 12 axillary artery cannulations, four off-pump, no-touch aorta coronary bypasses, and three ascending aortic replacements. The CVA rate was 3.04% in the pre-CT period and 0.73% in the post-CT period (p = 0.05).

CONCLUSIONS

Aggressive screening and avoidance of ascending aortic atheroma reduces stroke. Preoperative CT scans in patients at high risk may help identify aortic areas at risk before entering the operating room, lead to more thorough screening in the operating room, and result in a more aggressive strategy to avoid calcified areas.

The topography of aortic atherosclerosis enhances its precision as a predictor of stroke

BACKGROUND

Atherosclerosis of the thoracic aorta is an independent risk factor for stroke after cardiac surgery. No attention had so far been paid to its topography. The relationship between the topography of aortic atherosclerosis and stroke was studied in patients admitted for coronary surgery.

METHODS

The extent and location of atherosclerosis in the ascending aorta and arch was assessed intraoperatively with epiaortic ultrasound and transesophageal echocardiography in 611 consecutive patients. They were followed for 5.5 +/- 1.7 years (mean +/- SE), amounting to 3,358 patient-years.

RESULTS

The incidence of early postoperative (<30-day) stroke was 6.4% in patients with atherosclerosis of the ascending aorta and 1.5% in those without (p = 0.004). The five-year stroke-free survival rates (>30 days after the operation) for patients without aortic disease, with less than 50%, and with greater than 50% of the ascending aorta affected, were 95.3 +/- 0.9%, 91.8 +/- 2.1%, and 65.0 +/- 14.6%, respectively (p < 0.0001).

CONCLUSIONS

Atherosclerosis of the ascending aorta stands out as a predictor of late stroke. High risk is predominantly linked to atheromas in its distal part and lesser curvature.

The impact of increasing age on anatomic factors affecting carotid angioplasty and stenting

PURPOSE

Current evaluations of carotid artery angioplasty and stenting (CAS) have suggested equivalency compared with carotid endarterectomy (CEA). However, the incidence of stroke and death with CAS may be higher in elderly patients. We assessed the anatomic characteristics of patients undergoing CAS and compared them based on age older or younger than 80 years. The impact of age on the incidence of postoperative complications was also determined.

METHODS

From February 2003 to August 2005, 135 CAS procedures were performed in 133 patients. Digital subtraction angiograms for each patient were evaluated by two independent observers blinded to patient identifiers. Anatomic characteristics that impact the performance of CAS were assessed as either favorable or unfavorable. These included aortic arch elongation, arch calcification, arch vessel origin stenosis, common and internal carotid artery tortuosity, and treated lesion stenosis, calcification, and length. Postoperative events were defined as myocardial infarction, stroke, and death. Fisher's exact test and chi(2) tests were used to determine statistical significance (P < .05).

RESULTS

Of the 133 patients treated, 87 (65%) were men and 46 (35%) were women; and 37 (28%) were >or=80 years of age. The cohort >or=80 years old had an increased incidence of unfavorable arch elongation (P = .008), arch calcification (P = .003), common carotid or innominate artery origin stenosis (P = .006), common carotid artery tortuosity (P = .0009), internal carotid artery tortuosity (P = .019), and treated lesion stenosis (P = .007). No significant difference was found for treated lesion calcification or length. Perioperative cerebral vascular accidents occurred in four patients (3.0%, 3 with no residual deficit, 1 with residual deficit), myocardial infarction in three (2.2%), and one patient (0.8%) died secondary to a hemorrhagic stroke. The combined stroke, myocardial infarction, and death rate for the entire population was 3.7%. The rate was significantly increased in patients aged >or=80 years old (10.8%) compared with those aged <80 years old (1%, P = .012).

CONCLUSIONS

Elderly patients, defined as those aged >80 years, have a higher incidence of anatomy that increases the technical difficulty of performing CAS. This increase in unfavorable anatomy may be associated with complications during CAS. Although the small number of perioperative events does not allow for determination of a direct relationship with specific anatomic characteristics, the presence of unfavorable anatomy does warrant serious consideration during evaluation for CAS in elderly patients.

Aortic plaque distribution in relation to cross clamp and cannulation procedures during cardiac surgery

OBJECTIVE

Aortic atherosclerosis may cause cerebrovascular accidents in cardiac surgery. Aortic plaque distribution was analyzed in relation to surgical manipulation.

DESIGN

In 24 autopsy subjects the thoracic aorta was digitally analyzed by macro-anatomic mapping of plaques. Plaque density was compared in different anatomical segments. Hazards associated with surgical manipulation were blindly studied by superimposing cannulation and cross-clamp locations onto the maps.

RESULTS

Plaques were frequent. The anterior wall of the ascending/arch aorta had higher plaque density than its posterior side (p=0.039). However, an anterior plaque predicted to 83% a concomitant plaque in the posterior wall. Plaque formation correlated with age (p=0.004). The theoretical risk of interfering with a plaque during cannulation and/or clamp positioning was 46%.

CONCLUSIONS

Plaque formation is a frequent and age-dependent problem. In the surgery-exposed aorta, the anterior wall had higher plaque density than the posterior side, although the two sides showed strong plaque coexistence. Furthermore, there was an unexpectedly high risk of plaque interference during cannulation and/or clamp maneuvers if blindly performed. The present results emphasize the importance of epiaortic scanning.

Surgical treatment of heart failure in the elderly

Heart failure (HF) in elderly patients who may benefit from surgical therapy is usually secondary to ischemic or valvular heart disease. When referring such patients for surgery, life expectancy, along with the expectations of the patient and family with regard to the surgical treatment, must be considered. The goals of cardiac surgery in this patient population are to maintain or improve cardiac function, decrease HF episodes, reduce hospital admissions,and improve functional class. Safer surgical techniques developed during the last two decades have allowed high-risk patients well into their 80s to undergo complex cardiac operations with decreasing morbidity and mortality. Successful surgical intervention often leads to a more productive and independent life for elderly patients who have HF.

Cerebral physiology of cardiac surgical patients treated with the perfluorocarbon emulsion, AF0144

BACKGROUND

Perfluorooctyl bromide is a biologically inert compound with short biologic retention and high oxygen solubility. The purpose of this study was to assess the effect of the perfluorocarbon emulsion, AF0144 (Perflubron, Alliance Pharmaceutical Corp, San Diego, CA), used in conjunction with acute normovolemic hemodilution on cerebral blood flow and cerebral emboli measurements during coronary artery bypass grafting with cardiopulmonary bypass.

METHODS

Thirty-six adult cardiac surgical patients were enrolled in a single-institution, randomized, controlled, single-blind dose escalation trial. Autologous whole blood was harvested from each patient to target an on-bypass hematocrit of 20% to 22%. Placebo, low dose (1.8 g/kg) or high dose (2.7 g/kg) AF0144 was administered. Transcranial Doppler ultrasonography was used to quantitate cerebral emboli and xenon-133 clearance was used to measure cerebral blood flow.

RESULTS

Cerebral blood flow was increased in both AF0144-treated groups compared with placebo (p = 0.006, low dose vs control; p = 0.036, high dose vs control). Numbers of cerebral emboli were greater in the high-dose AF0144-treated group versus control during the time periods from aortic cannulation through aortic cross-clamp placement (p = 0.026) and from aortic cross-clamp placement through cross-clamp removal (p = 0.008).

CONCLUSIONS

The perfluorocarbon emulsion, AF0144, increased cerebral blood flow during cardiopulmonary bypass. In addition, total cerebral emboli load during bypass was greater in patients receiving high-dose AF0144.

Central nervous system injury associated with cardiac surgery

Millions of individuals with coronary artery or valvular heart disease have been given a new chance at life by heart surgery, but the potential for neurological injury is an Achilles heel. Technological advancements and innovations in surgical and anaesthetic technique have allowed us to offer surgical treatment to patients at the extremes of age and infirmity-the group at greatest risk for neurological injury. Neurocognitive dysfunction is a complication of cardiac surgery that can restrict the improved quality of life that patients usually experience after heart surgery. With a broader understanding of the frequency and effects of neurological injury from cardiac surgery and its implications for patients in both the short term and the long term, we should be able to give personalised treatments and thus preserve both their quantity and quality of life. We describe these issues and the controversies that merit continued investigation.

Off-pump coronary bypass surgery: risk of ischemic brain lesions in patients with atheromatous thoracic aorta

PURPOSE

The purpose of this study was to determine if there is an association between the proximal thoracic aortic (ascending aorta and aortic arch) atheroma and ischemic brain lesions on diffusion-weighted magnetic resonance imaging (DW-MRI) after on-pump (ONCAB) and off-pump (OPCAB) coronary artery bypass surgery.

METHODS

Patients who underwent ONCAB surgery (n = 13) and who had aortic atheroma > 2 mm were compared to a risk-adjusted prospective cohort of patients (n = 13) undergoing OPCAB surgery. Transesophageal echocardiography and epiaortic scanning were performed to assess the proximal thoracic aorta. Patients were evaluated for new ischemic brain lesions utilizing DW-MRI three to seven days after surgery. The NEECHAM confusion scale was used to evaluate patient consciousness.

RESULTS

The groups were comparable with respect to demographic data, and prevalence of preoperative risk factors. The extent and severity of aortic atheroma was similar in the two groups. The average maximum height of atheroma was 5.0 +/- 2.0 mm in the OPCAB and 4.8 +/- 1.9 in the ONCAB groups, respectively. The prevalence of new ischemic brain lesions on DW-MRI was 0% in the OPCAB group and 61% in the ONCAB group (P = 0.001). Patients in the OPCAB group were less confused during the first two postoperative days.

CONCLUSION

Patients with aortic atheroma > 2 mm may have a lower risk of new ischemic brain lesions as identified by DWMRI after OPCAB surgery. Patient stratification based upon aortic atheroma burden should be addressed in future trials designed to tailor treatment strategies to improve short- and long-term neurological outcomes in patients undergoing cardiac surgery.

Intraluminal aortic manipulation by means of intra-aortic filter, cannulation, and external clamp maneuvers evaluated versus dislodged embolic material

OBJECTIVES

Aortic atherosclerosis is an important risk factor for cerebrovascular accidents in cardiac surgery. An intra-aortic filter might reduce this risk. We aimed to analyze the risks for emboli associated with intraluminal aortic manipulation and intra-aortic filter handling in relation to cannulation and external clamp maneuvers.

METHODS

A model was designed with a cadaver aorta and retrograde perfusion (n = 16). A crossclamp was positioned on the ascending aorta and repeatedly opened under pressure to collect aliquots with dislodged particles. Cannulation was performed after 10 clamp maneuvers, followed by positioning and removing the intra-aortic filter, with each step followed by a washout sequence to collect perfusate. The removed filter was also analyzed. Evaluation was by means of digital image analysis, with differentiation of particles into different spectra.

RESULTS

Intra-aortic filter manipulation produced a significant washout of embolic particles; in particular, this was seen for the macroscopic cellular spectrum (P = .006 and P = .002 for filter insertion and removal, respectively). Particles were also found to be collected by the filter (P = .004). In addition, cannulation and aortic crossclamp manipulation generated a notable number of particles (P = .001 and P = .013, respectively).

CONCLUSIONS

The intra-aortic filter collects material during aortic manipulation. However, intraluminal aortic manipulation from filter handling can also dislodge particles, possibly related to shedding of intimal debris. This is in addition to substantial amounts of particles that are generated by aortic cannulation and aortic crossclamping.

Analysis of anatomic factors and age in patients undergoing carotid angioplasty and stenting

Recent data suggest that patient age >80 years may be associated with increased risk of periprocedural complications from carotid angioplasty and stenting (CAS). In this study, we analyzed anatomic risk factors in patients undergoing CAS based on age >80 or <80 years. Our hypothesis was that patients >80 would have more challenging anatomy. Between February 2003 and August 2004, 82 patients underwent CAS. Images for 57 lesions were available for review. Eighteen patients were > or =80 years old and 39 were <80. Cerebral protection devices, including EPI Filterwire, Percusurge, Accunet, and Angioguard, were used in all but two cases; and self-expanding stents (Wallstent, NexStent, Acculink, Precise) were placed in all. Arterial anatomic characteristics were assigned a score based on complexity and associated procedural risk. Characteristics evaluated using angiographic images were aortic arch elongation classification, arch calcification, common carotid/innominate stenosis, common carotid tortuosity, internal carotid tortuosity, index lesion length, index lesion calcification, and index lesion stenosis. Statistical analysis was performed using Fisher's exact test. CAS was successfully completed in 98% of cases. The two patients in whom we could not perform CAS were 79 and 83 years old. The anatomic characteristics that were statistically significantly more complex/severe in patients > or =80 were arch calcification (p = 0.045), common carotid/innominate stenosis (p = 0.023), common carotid tortuosity (p = 0.049), and internal carotid tortuosity (p = 0.032). There was no statistically significant difference in arch elongation classification, lesion length, lesion calcification, or stenosis severity (p = nonsignificant). Overall, patients > or =80 years had an increased incidence of complex anatomic risk factors compared to younger patients (p < 0.001). Cerebrovascular accident without residual deficits occurred in two patients; both were >80 years old. Complex arterial anatomy is more often present in patients >80 years and may explain the increased complication rates associated with CAS. Pre- or intraoperative consideration of these characteristics may help provide better risk assessment in candidates for CAS.

Cerebral microembolization during off-pump coronary artery bypass surgery with the Symmetry aortic connector device

OBJECTIVE

The use of aortic connector systems for proximal vein grafts in off-pump coronary artery bypass grafting might minimize aortic manipulation by eliminating the need for partial aortic clamping. The objective of this study was to asses whether use of a Symmetry connector (St Jude Medical, Inc, St Paul, Minn) reduced intraoperative cerebral embolization.

METHODS

Thirty-two consecutive patients underwent off-pump coronary artery bypass grafting. Sixteen patients received at least one mechanical proximal vein graft anastomosis with a Symmetry aortic connector system. Sixteen patients representing the control group underwent operations with standard suturing techniques using partial aortic clamping. During surgical intervention, all patients were monitored continuously with multifrequency transcranial Doppler scanning, which detected and differentiated cerebral emboli.

RESULTS

There were significantly more cerebral emboli in the Symmetry group (median, 36) compared with the control group (median, 11; P = .027). This was due to a higher number of gaseous emboli in the Symmetry group than in the control group (median, 27 vs 8; P = .014), whereas there was no significant difference regarding the number of solid emboli (median, 7 vs 3; P = .139).

CONCLUSION

Use of a Symmetry connector system during proximal vein graft anastomosis increased the number of emboli to the brain compared with a standard technique in coronary bypass surgery without cardiopulmonary bypass.

Evaluation of the cardiac surgery patient with MSCT

Advances in MSCT have enabled assessment of cardiac function and anatomy, and ECG gating has allowed increasingly accurate depiction of coronary artery grafts and native coronary arteries. These capabilities now offer a comprehensive evaluation of the preoperative surgical patient. This essay outlines the important imaging issues and opportunities in the evaluation of the cardiac surgery patient.

Hypothermic Circulatory Arrest Enables Aortic Valve Replacement in Patients With Unclampable Aorta

BACKGROUND

Atheroembolic complications associated with clamping a severely diseased ascending aorta during aortic valve replacement may result in unacceptable mortality and morbidity. Different management options include hypothermic circulatory arrest to replace the aortic valve, an aortic endarterectomy, or tube graft replacement of the aorta to allow safe application of cross-clamp before aortic valve replacement.

METHODS

From 1998 to 2004, 70 patients who underwent aortic valve replacement had an aorta that was unclampable. Median age was 76 years; 33 (47%) were women; 46 (66%) had concomitant coronary artery bypass grafting; 9 (13%) had concomitant mitral valve surgery; and 4 (6%) were reoperations. Hypothermic circulatory arrest was used to replace the aortic valve alone, to do an aortic endarterectomy, or replace the ascending aorta with a tube graft.

RESULTS

Operative mortality was 4%. There were 8 (11%) strokes and 1 (1.4%) transient ischemic attack. Statistical analysis showed no association between circulatory arrest period and occurrence of adverse cerebral events. There was no significant difference among the three groups when operative mortality and cerebral events were compared.

CONCLUSIONS

Hypothermic circulatory arrest is an important adjunct that allows aortic valve replacement to be performed with an acceptable mortality but with an increased risk of cerebral event in this high-risk and elderly group of patients.

Low Hematocrit During Cardiopulmonary Bypass is Associated With Increased Risk of Perioperative Stroke in Cardiac Surgery

BACKGROUND

The relationship between degree of hemodilution during cardiopulmonary bypass (CPB) and perioperative stroke has not been fully elucidated. The objective of this observational study was to evaluate the relationship between nadir hematocrit during CPB and perioperative stroke while adjusting for variables known to have an association with stroke and anemia.

METHODS

Perioperative data were prospectively collected on 10,949 consecutive patients who underwent cardiac surgery with CPB from 1999 to 2004 at a quaternary care hospital. Stroke was defined as a persistent neurologic deficit, consistent with a central nervous system lesion, occurring within 30 days of operation. Stroke was classified as perioperative if patients awoke from anesthesia with neurologic symptoms and postoperative if patients awoke without symptoms. Multivariable logistic regression analysis was used to control for confounding variables to obtain the independent relationship between nadir hematocrit during CPB and perioperative stroke.

RESULTS

The prevalence of perioperative stroke was 1.0% (n = 110). An additional 50 patients had postoperative stroke. Nadir hematocrit during CPB was an independent predictor of perioperative stroke. After controlling for confounding variables, each percent decrease in hematocrit was associated with a 10% increase in the odds of suffering perioperative stroke (95% confidence interval, 4% to 18%; p = 0.002). The model was accurate (c-index = 0.85) and reliable (Hosmer-Lemeshow test p = 0.4).

CONCLUSIONS

There is an independent, direct association between degree of hemodilution during CPB and risk of perioperative stroke. Prospective randomized clinical trials comparing different degrees of hemodilution during CPB are required to determine whether this is a cause-effect relationship or a simple association.