Management of the severely atherosclerotic aorta during cardiac operations

Is cardioplegia system pressure the optimal measure of coronary perfusion during antegrade cardioplegia delivery? A critical review of pressure measurements for optimal antegrade delivery

Antegrade cardioplegia is routinely given during cardiac surgery. The delivery of antegrade cardioplegia from the cardiopulmonary bypass machine has many variables. Many perfusionists rely exclusively on cardioplegia system pressure to ensure safe antegrade delivery. Our group reviewed antegrade cardioplegia delivery in 50 patients undergoing coronary artery bypass graft. The data collected included the cardioplegia system pressure and the patient's direct aortic root pressure. The analysis of the data found weak correlation between the two pressures with a large mean difference and a wide standard deviation. The results suggest the direct measurement of aortic root pressure as guidance to antegrade cardioplegia instead of relying solely on cardioplegia system pressure.

The Rationalisation of Intra-Operative Imaging During Cardiac Surgery: A Systematic Review

INTRODUCTION

One critical complication of cardiac surgery is cerebrovascular accidents (CVAs). Ascending aorta atherosclerosis poses a significant risk of embolisation to distal vessels and to cerebral arteries. Epi-aortic ultrasonography (EUS) is thought to offer a safe, high-quality accurate visualisation of the diseased aorta to guide the surgeon on the best surgical approach to the planned procedure and potentially improve neurological outcomes post-cardiac surgery.

METHOD

The authors conducted a comprehensive search of PubMed, Scopus and Embase. Studies that reported on epi-aortic ultrasound use in cardiac surgery were included. Major exclusion criteria were: (1) abstracts, conference presentations, editorials, literature reviews; (2) case series with <5 participants; (3) epi-aortic ultrasound in trauma or other surgeries.

RESULTS

A total of 59 studies and 48,255 patients were included in this review. Out of the studies that reported patient co-morbidities prior to cardiac surgery, 31.6% had diabetes, 59.5% had hyperlipidaemia and 66.1% had a diagnosis of hypertension. Of those that reported significant ascending aorta atherosclerosis found on EUS, this ranged from 8.3% of patients to 95.2% with a mean percentage of 37.8%. Hospital mortality ranged from 7% to 13%; four studies reported zero deaths. Long-term mortality and stroke rate varied significantly with hospital duration.

CONCLUSION

Current data have shown EUS to have superiority over manual palpation and transoesophageal echocardiography in the prevention of CVAs following cardiac surgery. Yet, EUS has not been implemented as a routine standard of care. Extensive adoption of EUS in clinical practice is warranted to aid large, randomised trials before making prospective conclusions on the efficacy of this screening method.

Perioperative Care of the Patient with Eye Pathologies Undergoing Nonocular Surgery

The authors reviewed perioperative ocular complications and implications of ocular diseases during nonocular surgeries. Exposure keratopathy, the most common perioperative eye injury, is preventable. Ischemic optic neuropathy, the leading cause of perioperative blindness, has well-defined risk factors. The incidence of ischemic optic neuropathy after spine fusion, but not cardiac surgery, has been decreasing. Central retinal artery occlusion during spine fusion surgery can be prevented by protecting eyes from compression. Perioperative acute angle closure glaucoma is a vision-threatening emergency that can be successfully treated by rapid reduction of elevated intraocular pressure. Differential diagnoses of visual dysfunction in the perioperative period and treatments are detailed. Although glaucoma is increasingly prevalent and often questions arise concerning perioperative anesthetic management, evidence-based recommendations to guide safe anesthesia care in patients with glaucoma are currently lacking. Patients with low vision present challenges to the anesthesia provider that are becoming more common as the population ages.

Toward stroke-free coronary surgery: The role of the anaortic off-pump bypass technique

Surgical coronary revascularization remains the preferred strategy in a significant portion of patients with coronary artery disease due to superior long-term outcomes. However, there is a significant risk of perioperative neurologic injury that has influenced guideline recommendations. These complications occur in 1%-5% of patients, ranging from overt neurologic deficits with permanent disability, to subtle cerebral defects noted on neuroimaging that may result in slow cognitive and functional decline. The primary mechanism by which these events occur is thromboembolism from manipulation of the ascending aorta. This occurs during cardiopulmonary bypass, aortic cross-clamping, and partial occlusion clamping (side clamp). Elderly patients and patients with aortic atheroma are, therefore, at significantly increased risk. Initial surgical techniques addressed this by aggressively debriding or replacing the ascending aorta during coronary artery bypass grafting (CABG). Strategies then moved toward minimizing aortic manipulation through pump-assisted beating heart surgery and off-pump surgery with partial occlusion clamping or proximal anastomosis devices. Finally, anaortic off-pump CABG aims to avoid all manipulation of the ascending aorta through advanced off-pump grafting techniques combined with in situ and composite grafts. This has been demonstrated to result in the greatest reduction in risk. Establishing successful anaortic off-pump CABG programs requires subspecialization and focused interest groups dedicated to advancing CABG outcomes.

Strategies to Protect the Brain During Cardiac Surgery

Despite significant advances in cardiopulmonary by pass (CPB) technology, surgical techniques, and anes thetic management, central nervous system (CNS) com plications remain a common and costly problem after CPB. Stroke is often considered a rare and unprevent able complication of cardiac surgery. Recent studies have shown that through the use of echocardiography and historical risk stratification strategies, we can de fine which patients are at substantially greater risk for CNS injury. Through enhanced understanding of the etiology of stroke and perioperative factors, which are associated with potential for neuroprotection or injury extension, there now exists a greater potential than ever to substantially reduce neurological injury associ ated with cardiac surgery. Strategies and theories of stratifying patients at risk and secondarily reducing that risk are described, as well as consideration for early postoperative assessment to allow treatment when events occur.

Strategies and Techniques for Neuroprotection in Coronary Artery Surgery

Patients undergoing coronary artery bypass grafting are at higher risk of neurologic events than demographi cally similar patients undergoing noncardiac surgery. Postoperative stroke has been shown to occur two to three times more frequently than in age-, gender-, and education-matched patients undergoing noncardiac vas cular or thoracic surgery. The incidence of more subtle brain syndromes, giving rise to symptoms of memory loss and cognitive deterioration as documented in up to 79% of coronary bypass patients, varies depending on whether prospective or retrospective data are analyzed, and whether or not serial cognitive testing is used, and is also significantly higher in coronary bypass patients. Various factors have been identified as causative in the genesis of perioperative neurologic injury in these pa tients. Although there is evidence that microgaseous and microparticulate emboli are instrumental in the production of postoperative cognitive impairment, the role of ascending aortic atherosclerosis is increasingly recognized as being the greatest single risk factor for postoperative stroke.

Percutaneous implantation of the CoreValve® self-expanding valve prosthesis in patients with severe aortic stenosis and porcelain aorta: medium-term follow-up

INTRODUCTION AND OBJECTIVES

There is little information on the use of transcatheter aortic valve implantation in patients with severe aortic stenosis and porcelain aorta. The primary aim of this study was to analyze death from any cause after CoreValve(®) implantation in patients with severe aortic stenosis, with and without porcelain aorta.

METHODS

In this multicenter, observational prospective study, carried out in 3 hospitals, percutaneous aortic valves were implanted in 449 patients with severely calcified aortic stenosis. Of these, 36 (8%) met the criteria for porcelain aorta. The primary end-point was death from any cause at 2 years.

RESULTS

Patients with porcelain aorta more frequently had extracardiac vascular disease (11 [30.6%] vs 49 [11.9%]; P=.002), prior coronary revascularization (15 [41.7%] vs 98 [23.7%]; P=.017), and dyslipidemia (26 [72.2%] vs 186 [45%]; P=.02). In these patients, there was greater use of general anesthesia (15 [41.7%] vs 111 [16.9%]; P=.058) and axillary access (9 [25%] vs 34 [8.2%]; P=.004). The success rate of the procedure (94.4 vs 97.3%; P=.28) and the incidence of complications (7 [19.4%] vs 48 [11.6%]; P=.20) were similar in both groups. There were no statistically significant differences in the primary end point at 24 months of follow-up (8 [22.2%] vs 66 [16%]; P=.33). The only predictive variable for the primary end point was the presence of complications during implantation (hazard ratio=2.6; 95% confidence interval, 1.5-4.5; P=.001).

CONCLUSIONS

In patients with aortic stenosis and porcelain aorta unsuitable for surgery, percutaneous implantation of the CoreValve(®) self-expanding valve prosthesis is safe and feasible.

Pre- and perioperative risk factors predicting neurologic outcomes after coronary artery bypass surgery in patients with pre-existing neurologic events

BACKGROUND

A neurologic event (NE) after coronary artery bypass graft (CABG) surgery is a principal complication affecting morbidity and mortality. We investigated the risk factors predicting postoperative NEs and survival in patients with pre-existing NE undergoing CABG.

METHODS

Between 2001 and 2012, 3137 patients underwent isolated primary CABG. The data were stored in a computerized database and retrospectively evaluated. Patients were divided into 2 groups based on the existence of preoperative NE (study group; n=126) and without NE (n=3011). Uni- and multivariate logistic regression analyses were performed to evaluate the possible predictors of postoperative NEs. Survival was determined using Kaplan-Meier survival analyses of the study group and propensity score-matched control group.

RESULTS

The mean age of the 3137 patients was 60±9 years, and 28% (n=885) were female. Postoperative NE was seen in 4 (3.2%) patients with pre-existing NE and in 16 (0.5%) without pre-existing NE. Preoperative NE (odds ratio 4.47; 95% confidence interval 1.32-15.18; P=.01) and age (≥70 years; odds ratio 2.98; 95% confidence interval 1.21-7.33; P=.01) showed strong multivariate associations with postoperative NE. Median CHA2DS2-VASc scores were 4.5 (interquartile range 3-5) and 3 (range 0-4) in patients in the pre-existing and without NE groups, respectively (P=.01). The overall mean follow-up was 4.6±3 years. Overall survival rates (88.1% and 94%, respectively) were different between the 2 groups (P=.02).

CONCLUSIONS

Preoperative neurologic events and advanced age are significant risk factors predicting postoperative neurologic events. Meticulous management of the ascending aorta and carotid artery are important in diminishing postoperative neurologic events. A pre-existing neurologic event is also predictive for decreased overall survival.

Clampless technique during coronary artery bypass grafting for proximal anastomoses in the hostile aorta

OBJECTIVE

The incidence of stroke in patients undergoing coronary artery bypass grafting increases sharply in the face of significant atherosclerotic disease of the ascending aorta. We use a technique that allows full revascularization for this cohort of patients, while minimizing cerebral embolic risk.

METHODS

Intraoperative epiaortic ultrasound was used to screen for moderate or severe atherosclerotic disease of the ascending aorta and to precisely identify safe areas for cannulation and proximal anastomoses. By using a mildly hypothermic fibrillating technique, distal revascularization was then performed without clamping the aorta. Proximal anastomoses were accomplished under brief periods of circulatory arrest.

RESULTS

We routinely use this technique and examined our results in 71 consecutive patients found to have grade 3 or greater atherosclerotic plaque of the ascending aorta. This represented approximately 10.0% of our total population who underwent coronary artery bypass grafting over a 32-month period from January 2007 to September 2009. One patient (1.4%) had a mild stroke that resolved, and there were no other neurologic complications.

CONCLUSIONS

We have found that clampless fibrillating heart surgery with circulatory arrest for proximal anastomoses is a safe and effective technique for revascularizing patients with significant ascending aortic disease who are at high risk for cerebral embolic complications.

An unusual origin of proximal coronary bypass anastomosis in a patient with porcelain aorta: how we solved the problem

Severe calcification of the ascending aorta (porcelain aorta) is a very difficult condition in cardiac surgery because of a high embolization potential during the process of cannulation, aortic cross-clamping and a particular difficulty to suture the proximal anastomosis. We described a case of a 68-year-old female referred to our Institute due to unstable angina. Further diagnostics revealed a severe high grade, multilevel fibrolipid symptomatic carotid stenosis and ostial left main coronary artery stenosis and a highly calcified ascending aorta and aortic arch. We performed simultaneous carotid segment replacement with the Dacron prosthesis and revascularisation of the left anterior descending coronary artery. Proximal venous anastomosis was created in the Dacron prosthesis of the right carotid artery. Perfusion of the patient was achieved via the graft sutured at the right subclavian artery due to impossibility of direct aortic cannulation.

Balloon occlusion of the ascending aorta without hypothermic circulatory arrest in valve surgery for patients with a porcelain aorta

Severe calcification of the ascending aorta and the aortic arch complicates cardiac surgery. The optimal approach in such patients is unknown. Four valve surgeries were performed with balloon occlusion without hypothermic circulatory arrest. All patients had femoral arterial cannulation, and all 3 patients who required an aortotomy had right axillary artery cannulation as well. A balloon catheter was inserted just proximal to the brachiocephalic artery via a purse-string stitch. Good cardiac arrest was obtained in all cases, and a good bloodless field was obtained in all 3 aortic valve cases. There were no balloon-related complications. The patients all showed good postoperative courses. Balloon occlusion of the ascending aorta without circulatory arrest is effective for performing a rapid and less invasive surgery that is not significantly different from the usual valve surgery.

Epiaortic ultrasound assessment of the aorta in cardiac surgery

The dislodgement of atheroma from the ascending aorta and proximal arch is a major cause of stroke and neurological injury following cardiac surgery. The accurate detection of atheroma prior to aortic manipulation is necessary to facilitate surgical strategies to reduce the risk of embolisation. The traditional method for atheroma detection is manual palpation by the surgeon. This technique misses about half the number of the atheroma lesions, as the soft (non-calcified) lesions offer little resistance to the surgeon's fingers. Trans-oesophageal echocardiography (TOE) is commonly used in cardiac surgery, but the interposition of the bronchus between the aorta and the oesophagus causes an ultrasound 'blind spot' in the ascending aorta and proximal arch, such that it does not offer improved detection compared to manual palpation. Accurate detection of atheroma requires direct ultrasound assessment using epiaortic scanning, with a high-frequency, linear-array probe. This allows the surgeon to correctly assess and localise any atheroma. In this article, a suggested epiaortic examination sequence is described and strategies for surgeons to avoid atheroma are discussed.

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.

Early results of a comprehensive operative and perfusion strategy to attenuate the incidence of adverse neurological outcomes in on-pump coronary artery bypass grafting (CABG) patients

Adverse neurological events, both focal (Type I) and non-focal (Type II), have been appreciated in postoperative on-pump coronary artery bypass grafting (CABG) patients for many years. Advanced age is a significant risk factor for adverse neurological events following CABG surgery. With full knowledge that our elderly population of patients was at high risk for these untoward neurological events, we adopted a comprehensive operative and perfusion strategy in an attempt to attenuate the incidence of these complications. Our strategy included efforts to minimise the number of emboli generated during the operation, avoid cerebral hypoperfusion, and attenuate the systemic inflammatory response. From 15 August 2002 to 31 December 2005, we performed 355 on-pump CABG operations. The incidence of Type I focal injury was 0/355 (0%), the incidence of Type II non-focal injury was 9/355 (2.5%), and postoperative mortality was 2/355 (0.6%). These results compared favorably to the results predicted by the Society of Thoracic Surgeons' (STS) model, and may suggest efficacy.

Apicoaortic valved conduit: Potential for progress?

OBJECTIVE

The number of elderly patients who require aortic valve replacement is growing, as is the increase of complicating factors, such as previous coronary bypass grafting and atherosclerotic disease of the ascending aorta. An uncommon surgical option to aortic valve replacement is the apicoaortic valved conduit. In this article the techniques and outcomes of 13 cases of apicoaortic valved conduit insertions in high-risk patients are described.

METHODS

From 2002 through 2005, 13 patients (mean age, 75 +/- 8.7 years; 8 men) with severe calcific aortic stenosis had insertions of an apicoaortic valved conduit because of a porcelain aorta (n = 4), previous coronary bypass grafting (n = 6), or both (n = 3). The off-pump technique was used in 9 patients, and a heparinized miniextracorporeal circulation system was used in 4 patients. Follow-up time was 6 to 33 months.

RESULTS

Mean intensive care stay was 2 +/- 2.7 days, and mean hospital stay was 12 +/- 8 days. The 30-day mortality was 15% (2 patients; postoperative days 3 and 28, both caused by myocardial infarction). Mortality later than 30 days postoperatively was 23% (3 patients; postoperative day 45 caused by bilateral pulmonary bleeding because of pneumonia, postoperative day 56 caused by myocardial infarction, and postoperative day 81 caused by pneumonia). The remaining 8 patients were doing well, all in New York Heart Association class I or II at follow-up, with echocardiography showing a low gradient over the valved conduit.

CONCLUSIONS

The apicoaortic valved conduit in high-risk patients undergoing aortic valve replacement remains a feasible option, with a substantial potential for technical development and progress.

Clampless Anastomosis: Novel Device for Clampless Proximal Vein Anastomosis in OPCAB Surgery--The Initial Spyder Experience

The Spyder is a novel device that enables the attachment of a vein to the aorta by compliant, interrupted anastomosis; this minimizes aortic manipulation during off pump-coronary artery bypass (OPCAB) surgery. Its use may reduce transcranial Doppler signals recorded during CABG. We performed 250 anastomoses in 160 OPCAB cases in many centers and recorded efficiency and efficacy data. There were no adverse events noted during the operative period. In a subset of patients in one center, flow (n = 48) and transcranial Doppler signals (n = 22) were measured. We found the device to be a useful adjunct for minimally invasive CABG surgery.

No-Clamp Technique for Valve Repair or Replacement in Patients With a Porcelain Aorta

BACKGROUND

Patients requiring valvular heart surgery may have circumferential calcification of the ascending aorta. A variety of creative procedures have been described for managing this "porcelain aorta." We describe a technique based on replacement of the ascending aorta and proximal arch under profound hypothermic circulatory arrest, followed by the valve procedure.

METHODS

Twenty-five consecutive patients with a porcelain aorta were referred for heart valve surgery. In every case the aorta was replaced under circulatory arrest before the valve procedure. Postoperative morbidity, mortality, and univariate risk factors for death were calculated. Fisher's exact test defined significant perioperative variables with a p value less than 0.05.

RESULTS

Of 25 patients, 23 (92%) survived the surgery to hospital discharge. One patient had a stroke (4%) and 2 patients (8%) required reexploration for bleeding. Risk factors for perioperative death by univariate analysis included age more than 78 years (p < 0.009), cardiopulmonary bypass time longer than 200 minutes (p < 0.0001), reexploration for bleeding (p < 0.02), need for intra-aortic balloon pump support (p < 0.001), and postoperative gastrointestinal complications (p < 0.001).

CONCLUSIONS

Valve replacement or repair in the patient with a porcelain aorta can be safely accomplished with a technique based on aortic replacement under circulatory arrest. Elderly patients requiring extensive procedures and prolonged periods on bypass have a substantially increased risk for postoperative complications and death.

Does the arterial cannulation site for circulatory arrest influence stroke risk?

BACKGROUND

We investigated whether axillary/subclavian artery inflow with a side graft decreases the risk of stroke versus cannulation at other sites during hypothermic circulatory arrest.

METHODS

Between January 1993 and May 2003, 1,352 operations with circulatory arrest were performed for complex adult cardiac problems. A single arterial inflow cannulation site was used in 1,336 operations, and these formed the basis for comparative analyses. Cannulation sites were axillary plus graft in 299 operations, direct cannulation of the aorta in 471, femoral in 375, innominate in 24, and axillary or subclavian without a side graft in 167. Retrograde brain perfusion was used in 933 (69%). A total of 272 (20%) were for emergencies, 432 (32%) were reoperations, and 439 (32%) were for dissections. A total of 617 (46%) had aortic valve replacement and 1,160 (87%) ascending, 415 arch (31%), and 248 descending (18%) aortic replacements. Indications also included arteriosclerosis (n = 301) and calcified aorta (n = 278). Primary comparisons were made by using propensity matching, and, secondarily, risk factors for stroke or hospital mortality were identified by multivariable logistic regression.

RESULTS

Stroke occurred in 6.1% of patients (81/1,336): 4.0% (12/299) of those had axillary plus graft and 6.7% who had direct cannulation (69/1,037; p = 0.09; p = 0.05 among propensity-matched pairs). Operative variables associated with stroke included direct aortic cannulation, aortic arteriosclerosis, descending aorta repair, and mitral valve replacement. The risk of hospital mortality was higher (11%; 42/375) for patients who had femoral cannulation than axillary plus graft (7.0%; 21/299; p = 0.06; p = 0.02 among propensity-matched pairs).

CONCLUSIONS

Axillary inflow plus graft reduces stroke and is our method of choice for complex cardiac and cardioaortic operations that necessitate circulatory arrest. Retrograde or antegrade perfusion is used selectively.

Atherosclerosis of the ascending aorta as a major determinant of the outcome of cardiac surgery

Epiaortic ultrasonography has high sensitivity for the detection of atherosclerosis. In several studies, the technique has identified atherosclerosis of the ascending aorta as the major risk factor for stroke after cardiac surgery. The level of risk depends on the presence, location and extent of disease when the ascending aorta is surgically manipulated. This knowledge enables clinicians to focus on the diagnostic and surgical technique and to consider the various options. Routine use of intraoperative epiaortic ultrasonography should be applied so that surgical manipulation of the ascending aorta can be reduced or, if possible, avoided in patients with atherosclerosis of the ascending aorta. Alternatively, if major manipulation such as clamping must be performed in the presence of severe atherosclerosis, the use of intra-aortic filters could be considered.

The use of the SonoSite ultrasound device for intraoperative evaluation of the aorta

OBJECTIVE

Neurologic complications remain a significant cause of morbidity and mortality in cardiac surgery. Risk factors for neurologic injuries include the presence of atheromatous disease in the aorta. Epiaortic ultrasound has been shown to be superior in detecting the extent and location of atheromatous disease. The SonoSite Corporation (Bothell, WA) has recently introduced an affordable, portable, high-resolution ultrasound device. This new device was compared with the Hewlett-Packard Sonos 5550 ultrasound device (currently manufactured by Philips, Andover, MA) to determine suitability for this purpose.

DESIGN

Prospective, serial comparison of 2 devices.

SETTING

University hospital.

PARTICIPANTS

Fifty consecutive cardiac surgery patients.

INTERVENTIONS

Intraoperative epiaortic ultrasound images were obtained using a SonoSite 180 Plus ultrasound device and a Hewlett-Packard Sonos 5500 ultrasound device. Three observers graded recorded images based on extent of atheromatous disease.

MEASUREMENTS AND MAIN RESULTS

Two patients were excluded because of errors in recording images. For the 48 remaining patients, consensus (median) grades had an observed agreement of 93.6% compared with a chance agreement of 67.7%. This correlates to a kappa value of 0.80 or near-excellent agreement.

CONCLUSIONS

The near-excellent agreement of the 2 devices is acceptable, thus providing a unique opportunity to expand the use of epiaortic ultrasound imaging.

Risk Factors for Stroke Following Coronary Artery Bypass Operations

BACKGROUND

Although the overall complication rates have been decreased significantly in recent years, stroke rates still remain high in patients undergoing coronary bypass operations. This study is designed to evaluate the risk factors for stroke in patients who had undergone coronary artery bypass surgery in an 8-year period in our clinic.

METHODS

Between 1995 and 2003, 8547 coronary artery operations under cardiopulmonary bypass were performed. Retrospective analysis of the patient files revealed that 75 (0.9%) patients had stroke in the early postoperative period.

RESULTS

Mean age of these patients was 62.3 +/- 9.5 years, and 54 (72%) were males. Stroke rate was 1.2% between 1995 and 1998 and this was significantly higher from the stroke rate (0.7%) of the period 1998 to 2003 (p = 0.03). Major technical differences between these two periods were the routine application of preoperative carotid arteries Doppler evaluation and intraoperative epiaortic echocardiography after 1998. Higher age (p = 0.000), female sex (p = 0.005), smoking (p = 0.03), presence of diabetes mellitus (p = 0.01), hypertension (p = 0.008), and left main coronary artery disease (p = 0.001), carotid surgery (p = 0.000), and peripheral vascular disease (p = 0.049) were identified as important risk factors in univariate analysis for stroke development. Higher age (p = 0.000; OR = 21.38), left main coronary artery disease (p = 0.007; OR = 7.26), peripheral vascular disease (p = 0.050; OR = 3.08), and operation date before 1998 (p = 0.012; OR = 6.33) were identified as important risk factors in logistic regression analysis. According to intraoperative epiaortic ultrasonography, operative strategy was changed in 9% of patients. Thirty-seven (49.3%) of the stroke patients died. Female sex (p = 0.023; OR = 5.18) and preoperative hypertension (p = 0.045; OR = 4.03) were observed as significant risk factors for mortality after stroke.

CONCLUSION

Development of stroke is one of the major reasons of mortality after coronary artery bypass operations. It is essential to take all the measures to prevent this complication, especially in patients with known risk factors. Evaluation of carotid arteries prior to operation and application of routine intraoperative epiaortic echocardiography may in part eliminate stroke.

Neuroprotection During CPB: From Mechanisms to Interventions

The incidence and etiology of brain dysfunction after conventional coronary artery bypass surgery using cardiopulmonary bypass are reviewed. Stroke rates and incidences of cognitive dysfunction from various studies are considered. Mechanisms of injury including cerebral embolization as detected by transcranial Doppler and evidence for postoperative cerebral edema are discussed. Evidence for lower overall postoperative morbidity, and for a lower incidence of cognitive dysfunction specifically, after nonpump coronary revascularization is presented.

Operative and 5-year outcomes of combined carotid and coronary revascularization: review of a large contemporary experience

BACKGROUND

Surgical treatment of concomitant coronary and carotid disease is controversial. Studies comparing staged versus combined coronary artery bypass grafting and carotid endarterectomy (CABG/CEA) report varying and often conflicting operative results. Also, few studies have investigated the long-term outcomes of combined surgery.

METHODS

We reviewed the operative outcome and 5-year survival results of 189 consecutive patients (69+/-9 years old, 66 [35%] female patients) who underwent combined CABG/CEA between 1994 and 1999. Survival follow-up was conducted in February 2001 and the incidence of late stroke, carotid surgery, and myocardial infarction was investigated in all surviving patients by mail survey. A phone interview was done by a surgeon of patients with late strokes or repeated CEA.

RESULTS

Operative death occurred in 5 of 189 patients (2.65%) 4 of which were in-hospital deaths. A total of 5 (2 permanent, 3 transient [2.65%]) perioperative strokes were documented in these patients, and 1 of the perioperative strokes patients died in the hospital. In all, 156 of 189 patients (82.5%) were alive at the time of the study and completed surveys were collected from 153 of 156 patients (98%). Of these 153 patients, 4 reported a late stroke (2.6%), 5 suffered a myocardial infarction (3.3%), and 16 (10.5%) underwent subsequent CEA (7 ipsilateral to original CEA). Angioplasty (3 of 153, 2.0%) and redo surgery (1 of 153, 0.66%) occurred infrequently. Median survival follow-up was 51 months (range 12 to 84), and the corresponding 5-year Kaplan-Meier survival was 79.4%. This survival was similar to that of age-matched isolated CABG patients (n = 532) with documented history of cerebrovascular disease but no surgical carotid lesions.

CONCLUSIONS

Our results suggest that combined CABG/ CEA is safe and may in fact reduce the risk of adverse outcomes in the intermediate term compared with age and risk-matched patients. We speculate the latter may be attributable to a cerebrovascular protective effect of CABG/CEA pending verification by randomized trials. An economic benefit of CABG/CEA may also be inferred from avoiding separate coronary and carotid operations and reduction in the high costs of perioperative stroke.

Neurological and cognitive disorders after coronary artery bypass grafting

Cerebral injury is a major cause of mortality and morbidity of coronary artery bypass grafting. Stroke occurs in 3% of patients and is largely caused by embolization of atheromatous debris during manipulation of the diseased aorta. Cognitive impairment, which is predominantly caused by microembolization of gaseous and particulate matter, mainly generated by cardiotomy suction, is more common. Demonstration of similar cognitive impairment in patients operated on without cardiopulmonary bypass indicates that other pathophysiological mechanisms, such as anaesthesia and hypoperfusion, are also involved. Advances in medical, anesthetic, and surgical management have resulted in a reduction in the incidence of neurological injury in CABG patients over the past decade. On the other hand, an increasingly elderly population with more severe comorbidity, who are more prone to cerebral injury, are increasingly being referred for CABG. Possible mechanisms to reduce overt and subtle cerebral injury are discussed. The use of composite arterial grafts performed on the beating heart may be the most effective way of minimizing the risk of cerebral injury associated with CABG.

Beating heart surgery or conventional CABG: are neurologic outcomes different?

Although there has been much debate about the causes of neurologic complications associated with coronary artery bypass grafting (CABG), there is good evidence linking such complications with some of the pathophysiologic changes associated with use of conventional cardiopulmonary bypass (CPB). Several studies indicate that it is possible to significantly lower risk of stroke and other central nervous system (CNS) morbidity in patients undergoing CPB for CABG by application of selected techniques and equipment modifications. The resurgence of interest in coronary revascularization by using beating heart surgery (BHS) offers a unique opportunity to evaluate neurologic outcome independent of CPB. Currently, BHS would appear to significantly reduce morbidity in the elderly and to decrease the costs and resource use in coronary revascularization patients. It is hoped that by understanding the mechanisms of CNS injury associated with CABG, techniques can be developed to decrease the risk of neurologic injury associated with coronary revascularization, whether or not CPB is used. Definitive conclusions regarding outcomes after best practice CPB or BHS await large-scale, risk-stratisfied multicenter trials.

Neurologic injury in cardiac surgery: aortic atherosclerosis emerges as the single most important risk factor

With older and sicker patients undergoing cardiac surgery, neurologic injury has emerged as an increasingly important cause of rising costs, morbidity and mortality. Several studies investigating the relationship between atherosclerotic aortic disease and subsequent adverse clinical outcomes have demonstrated that the single most important risk factor for neurologic injury following cardiac surgery is the presence of aortic atheromatous disease. The results of these studies suggest that atheroemboli are correlated with neurologic injury following cardiac surgery. Surgical techniques to avoid and prevent particulate debris during cardiac surgery may be a major step in preventing severe neurologic injury.

The atherosclerotic aorta at aortic valve replacement: surgical strategies and results

BACKGROUND

Aortic valve replacement in patients with severe atherosclerosis of the ascending aorta poses technical challenges. The purpose of this study was to examine operative strategies and results of aortic valve replacement in patients with a severely atherosclerotic ascending aorta that could not be safely crossclamped.

PATIENTS AND METHODS

From January 1990 to December 1998, 4983 patients had aortic valve surgery; of these, 62 (1.2%) patients had a severely atherosclerotic ascending aorta and required hypothermic circulatory arrest to facilitate aortic valve replacement. They form the study group.

RESULTS

All patients had hypothermic circulatory arrest, but several different strategies were used to manage the ascending aorta. These techniques included aortic valve replacement with the use of hypothermic circulatory arrest (39%), ascending aortic endarterectomy (26%), ascending aortic replacement (19%), aortic inspection and crossclamping during hypothermic circulatory arrest (10%), and balloon occlusion of the ascending aorta (6%). Duration of hypothermic circulatory arrest was substantially longer for patients having aortic valve replacement with hypothermic circulatory arrest than for all other strategies. Hospital mortality was 14%, and 10% of patients had strokes. Increasing New York Heart Association functional class and impaired left ventricular function were risk factors for hospital mortality. Choice of operative technique did not influence patient outcome; however, no patient who underwent replacement of the ascending aorta had a stroke.

CONCLUSIONS

Aortic valve replacement in patients with severe atherosclerosis of the ascending aorta is associated with increased operative morbidity and mortality. Complete aortic valve replacement during hypothermic circulatory arrest, the "no-touch" technique, requires a prolonged period of circulatory arrest. Ascending aortic replacement is a preferred technique, as it requires a short period of hypothermic circulatory arrest and results in comparable mortality with a low risk of stroke.

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.

Delayed chronic type A dissection following CABG: implications for evolving techniques of revascularization

BACKGROUND

Postoperative dissection in some patients is related to manipulation of the aorta and accounts for 3% to 5% of deaths after cardiac surgery.

METHODS

Between 1987 and 1999, 109 patients with previous cardiac operations were treated for chronic type A dissection. In 31 of the patients, the etiology was related to aortic manipulation. Twenty-one patients (17 men, 4 women; 67+/-13 years of age) had isolated coronary artery bypass grafting (CABG) as their first operation and were reviewed. The interval between operations was 52.9+/-47.3 months.

RESULTS

Reoperation was elective in 11 patients, urgent in 10 patients. Median maximal aortic diameter was 6.8+/-2.1 cm; 9 patients had major aortic insufficiency. The intimal tear was at the partial occlusion clamp site in 12 patients (57.1%), at the cross-clamping site in 4 patients (19.1%), and at the proximal anastomosis in 1 patient (4.8%); 4 patients (19.1%) had multiple tears at several sites. Cystic media necrosis was present in 9.5% of the patients, severe atherosclerosis in 47.6% of the patients, and 42.9% of the patients had both. Nine patients (42.9%) underwent a modified Bentall procedure, 12 patients (57.1%) underwent a supracoronary anastomosis, and all had open distal anastomosis. There were two (9.5%) hospital deaths and three (14.3%) postoperative strokes. Freedom from cardiac or aorta-related mortality was 85.7% at a mean follow-up of 49.3 months.

CONCLUSIONS

In patients who develop type A dissection of the aorta after previous CABG, the intimal tear most often is at partial occlusion clamp site. This complication is associated with morbidity and mortality. It remains to be seen whether the use of partial occlusion clamps on the pulsating and often diseased aorta during off-pump coronary artery bypass (OPCAB) will increase the risk of delayed iatrogenic dissections.

Neurologic complications of cardiac surgery

The average age of patients undergoing cardiac surgery and the number of comorbidities they possess will continue to increase as surgical technology advances. Toxic/metabolic encephalopathy, hemispheric strokes, hypoxic injury, and peripheral nerve lesions all can occur as a result of cardiac surgery. Therefore, an understanding of the neurologic risk, recognizable syndromes, and preventative measures will continue to be important. Careful preoperative assessment, operative risk factor reduction, and careful postoperative assessments and management may reduce the neurologic risk for cardiac surgery.

Reduced neuropsychological dysfunction using epiaortic echocardiography and the exclusive Y graft

BACKGROUND

To examine the effect of screening the aorta for atheroma before aortic manipulation and use of exclusive Y graft revascularization on the incidence of neuropsychological dysfunction after coronary artery bypass.

METHODS

Aortic atheroma was detected using epiaortic and transesophageal echocardiography. Atheroma avoidance was facilitated by use of the exclusive Y graft technique, which has no aortic coronary anastomoses. In the control group aortic atheroma was assessed by manual palpation, and we attempted to avoid any atheroma detected. In this group we also used aorta-coronary grafts. Transcranial Doppler imaging of the right middle cerebral artery was used to detect cerebral microemboli. Neuropsychological dysfunction was defined as a 20% or more decline in score for at least 20% of a neuropsychometric battery of ten tests for each patient.

RESULTS

Late dysfunction at 57 +/- 2 days postoperatively in the control group was 38.1% and in the echo/Y group was 3.8% (p' = 0.012). Microemboli detected by transcranial Doppler imaging during periods of aortic manipulation was greater for those with late dysfunction (5.2 +/- 3.0 compared with 0.5 +/- 0.2) (p' = 0.018). No clinical strokes occurred in either group.

CONCLUSIONS

The combined techniques of epiaortic screening and exclusive Y graft for coronary artery bypass operations resulted in a low incidence of late neuropsychological dysfunction.

Risk factors for early or delayed stroke after cardiac surgery

BACKGROUND

Stroke after cardiac surgery is a devastating complication that leads to excess mortality and health resource utilization. The purpose of this study was to identify risk factors for perioperative stroke, including strokes detected early after cardiac surgery or postoperatively.

METHODS AND RESULTS

Data were obtained from 2972 patients undergoing coronary artery bypass graft and/or valve surgery. Patients >/=65 years old and those with a history of symptomatic neurological disease underwent preoperative carotid artery ultrasound scanning. Intraoperative epiaortic ultrasound to assess for ascending aorta atherosclerosis was performed in all patients. New strokes were considered as a single end point and were categorized with respect to whether they were detected immediately after surgery (early stroke) or after an initial, uneventful neurological recovery from surgery (delayed stroke). Strokes occurred in 48 patients (1.6%); 31 (65%) were delayed strokes. By multivariate analysis, prior neurological event, aortic atherosclerosis, and duration of cardiopulmonary bypass were independently associated with early stroke, whereas predictors of delayed stroke were prior neurological event, diabetes, aortic atherosclerosis, and the combined end points of low cardiac output and atrial fibrillation. Female sex was associated with a 6.9-fold increased risk of early stroke and a 1.7-fold increased risk of delayed stroke. In-hospital mortality of patients with early (41%) and delayed (13%) strokes was higher than that of other patients (3%, P=0.0001).

CONCLUSIONS

Most strokes after cardiac surgery occurred after initial uneventful recovery from surgery. Women were at higher risk to suffer early and delayed perioperative strokes. Atrial fibrillation had no impact on postoperative stroke rate unless it was accompanied by low cardiac output syndrome.

Surgical treatment of the dilated ascending aorta: when and how?

BACKGROUND

The aorta is considered pathologically dilated if the diameters of the ascending aorta and the aortic root exceed the norms for a given age and body size. A 50% increase over the normal diameter is considered aneurysmal dilatation. Such dilatation of the ascending aorta frequently leads to significant aortic valvular insufficiency, even in the presence of an otherwise normal valve. The dilated or aneurysmal ascending aorta is at risk for spontaneous rupture or dissection. The magnitude of this risk is closely related to the size of the aorta and the underlying pathology of the aortic wall. The occurrence of rupture or dissection adversely alters natural history and survival even after successful emergency surgical treatment.

METHODS

In recommending elective surgery for the dilated ascending aorta, the patient's age, the relative size of the aorta, the structure and function of the aortic valve, and the pathology of the aortic wall have to be considered. The indications for replacement of the ascending aorta in patients with Marfan's syndrome, acute dissection, intramural hematoma, and endocarditis with annular destruction are supported by solid clinical information. Surgical guidelines for intervening in degenerative dilatation of the ascending aorta, however, especially when its discovery is incidental to other cardiac operations, remain mostly empiric because of lack of natural history studies. The association of a bicuspid aortic valve with ascending aortic dilatation requires special attention.

RESULTS

There are a number of current techniques for surgical restoration of the functional and anatomical integrity of the aortic root. The choice of procedure is influenced by careful consideration of multiple factors, such as the patient's age and anticipated survival time; underlying aortic pathology; anatomical considerations related to the aortic valve leaflets, annulus, sinuses, and the sino-tubular ridge; the condition of the distal aorta; the likelihood of future distal operation; the risk of anticoagulation; and, of course, the surgeon's experience with the technique. Currently, elective root replacement with an appropriately chosen technique should not carry an operative risk much higher than that of routine aortic valve replacement. Composite replacement of the aortic valve and the ascending aorta, as originally described by Bentall, DeBono and Edwards (classic Bentall), or modified by Kouchoukos (button Bentall), remains the most versatile and widely applied method. Since 1989, the button modification of the Bentall procedure has been used in 250 patients at Mount Sinai Medical Center, with a hospital mortality of 4% and excellent long-term survival. In this group, age was the only predictor of operative risk (age > 60 years, mortality 7.3% [9/124] compared with age < 60, mortality 0.8% [1/126], p = 0.02).

CONCLUSIONS

This modification of the Bentall procedure has set a standard for evaluating the more recently introduced methods of aortic root repair.

Neurological complications of cardiac surgery: the need for new paradigms in prevention and treatment

Neurological injury is a devastating complication of cardiac surgery that results in a longer duration of hospitalization, increased costs, and increased likelihood of death. Such injury can affect any level of the central nervous system, and its manifestations are broad, ranging from neurocognitive dysfunction to frank stroke. Many variables have been found to be indicative or risk for perioperative neurological injury, but the predictive models are more useful for stroke risk than for neurocognitive dysfunction. Strategies aimed at reducing neurological injury during cardiac surgery have focused, for the most part, on the technical aspects of cardiopulmonary bypass. The concomitant performance of carotid endarterectomy and cardiac surgery continues to be controversial, although the management of patients with symptomatic carotid stenosis is better defined. Cerebral embolism, including atheroembolism from the ascending aorta, has an important role in the pathogenesis of neurological injury of all types. Epiaortic ultrasound imaging of the aorta is a sensitive technique for the identification of atherosclerosis of the ascending aorta at the time of surgery, which can allow it to be avoided and therefore reduce the risk for atheroembolism. Results of laboratory investigations have provided insight into the mechanisms of ischemic neuronal injury and a basis for the development of neuroprotective drugs. Neuroprotection may best be accomplished during cardiac surgery because, in contrast to nonsurgical situations, potential agents can be administered before the neurological insult occurs. Reducing the incidence of perioperative stroke will require a multidisciplinary approach that includes novel diagnostic and therapeutic strategies.