Cardiovascular morbidity and CABG surgery--a perspective: epidemiology, costs, and potential therapeutic solutions

The hydromechanics in arteriogenesis

Coronary heart diseases are tightly associated with aging. Although current revascularization therapies, such as percutaneous coronary interventions (PCI) and coronary artery bypass graft (CABG), improve the clinical outcomes of patients with coronary diseases, their application and therapeutic effects are limited in elderly patients. Thus, developing novel therapeutic strategies, like prompting collateral development or the process of arteriogenesis, is necessary for the treatment of the elderly with coronary diseases. Arteriogenesis (ie, the vascular remodeling from pre‐existent arterioles to collateral conductance networks) functions as an essential compensation for tissue hypoperfusion caused by artery occlusion or stenosis, and its mechanisms remain to be elucidated. In this review, we will summarize the roles of the major hydromechanical components in laminar conditions in arteriogenesis, and discuss the potential effects of disturbed flow components in non‐laminar conditions.

Impact of Discontinuation of Antiplatelet Therapy Prior to Isolated Valve and Combined Coronary Artery Bypass Graft and Valve Procedures on Short and Intermediate Term Outcomes

BACKGROUND

A change in cardiac surgery practice over the past decade has seen an increase in urgent or inpatient referrals for surgery, with antiplatelet therapy often continued up until surgery. This study aims to identify the optimal timing for administration of aspirin to minimise risk of perioperative morbidity and mortality.

METHODS

From a prospectively compiled database collected by the Australian and New Zealand Society of Cardiac and Thoracic Surgeons, we identified 8294 patients undertaking combined CABG and valve or isolated valve procedures while discontinuing aspirin. Time points for cessation of antiplatelet therapy were categorised as follows: <2 days, 3-7 days or >7 days preoperatively. We evaluated the association of adverse in-hospital events and intermediate term survival in each time category.

RESULTS

Discontinuing aspirin 3 to 7 days from surgery decreased rates of perioperative MI (HR=0.300, p=0.027), return to theatre (HR=0.560, p=0.002) reduced drain output (HR=0.757, p=0.000) and red blood cell and platelet transfusions (HR=0.719, p=0.000 and HR=0.604, p=0.000 respectively) compared to patients continuing aspirin until <2 days from the procedure. Stopping aspirin <2 days from the date of surgery increased risk of perioperative MI (HR=5.919, p=0.000), reoperation for bleeding (HR=2.076, p=0.001), returning to theatre (HR=1.781, p=0.000), ICC drain losses (HR=1.337, p=0.000) and transfusion demands for red blood cells (HR=1.381, p=0.000) and platelets (HR=1.450, p=0.000) when compared to those discontinuing aspirin >7 days from surgery.

CONCLUSION

Late discontinuation of aspirin before combined coronary artery bypass graft and valve procedures results in greater rates of bleeding and transfusion requirements. Earlier discontinuation of aspirin results in no benefit in intermediate term survival.

Variable Definitions: Implications for the Prediction of Pulmonary Complications after Adult Cardiac Surgery

AIM

The aim of this paper was to review the implications that variable definitions have for the prediction of post-operative pulmonary complications after cardiac surgery.

METHOD

A review of the literature from 1980 to 2002. Selected studies demonstrated an original attempt to examine multivariate associations between pre, intra or post-operative antecedents and pulmonary outcomes in patients undergoing coronary artery bypass grafting (CABG). Reports that described the validation of established clinical prediction rules, testing interventions or research conducted in non-human cohorts were excluded from this review.

RESULTS

Consistently, variable factor and outcome definitions are combined for the development of multivariate prediction models that subsequently have limited clinical value. Despite being prevalent there are very few attempts to examine post-operative pulmonary complications (PPC) as endpoints in isolation. The trajectory of pulmonary dysfunction that precedes complications in the post-operative context is not clear. As such there is little knowledge of post-operative antecedents to PPC that are invariably excluded from model development.

CONCLUSION

Multivariate clinical prediction rules that incorporate antecedent patient and process factors from the continuum of cardiovascular care for specific pulmonary outcomes are recommended. Models such as these would be useful for practice, policy and quality improvement.

Cognitive processing speed mediates the effects of cardiovascular disease on executive functioning

OBJECTIVE

The goal of this study was to examine the hypothesized mediating role of cognitive processing speed (CPS) in the relationship between cardiovascular disease (CVD) and executive functioning (EF). We investigated whether the processing-speed hypothesis in aging also explains the unique contribution that CPS may have to EF deficits in CVD patients.

METHOD

A neuropsychological assessment, including multiple measures of CPS and EF, was administered to 21 older adults with a history of CVD and 73 older adults with no history of CVD. Structural equation models were used to measure the indirect associations between CVD and 6 EF task outcomes through a CPS factor. Competing indirect links were assessed using the product-of-coefficients (α*β) approach with bias-corrected bootstrap confidence intervals.

RESULTS

CVD was significantly, negatively related to CPS (β = -.239, 95% CI [-.457, -.021]). CPS was significantly, positively related to an EF composite score (β = .566, 95% CI [.368, .688]). CVD was significantly, negatively related to the EF composite score (β = -.137, 95% CI [-.084, -.211]). The indirect links from CVD to the individual measures of the EF composite score via CPS were all significant. CVD most adversely affected tasks of cognitive flexibility and inhibition indirectly through CPS.

CONCLUSION

With the present study, we have demonstrated that the processing-speed hypothesis in aging extends to older adult patients with CVD. Reduced CPS significantly underlies the link between CVD status and poorer EF. Individuals with CVD demonstrated poorer CPS and EF than those without CVD, and CPS was specifically implicated as a CVD-related mechanism leading to worse EF. (PsycINFO Database Record

Diagnosing Perioperative Myocardial Infarction in Cardioth oracic and Vascular Surgery

Patients undergoing cardiac and high-risk noncardiac surgery have a high incidence of perioperative myocardial infarction. The early diagnosis of perioperative myocardial injury in these patients is complicated. In the perioperative period, there is a high incidence of nonspecific electrocardiographic changes and cardiac biomarker release. It is becoming increasingly imortant to differentiate myocardial necrosis from nonspecific changes because of the need for early intervention and the poential long term implications of a perioperative myocardial event. Although sensitive and specific assays to assess myoardial damage have been developed, specific thresholds to establish the occurrence a significant perioperative event have not been firmly defined. This review will attempt to outline the current evidence supporting the use of clinical symptoms, electrocardiographic changes, and cardiac biomarkers in the diagnosis of perioperative myocardial infarction and the longerm implication of these findings.

Genetic Predictors of Perioperative Neurologic and Neuropsychological Injury and Recovery

Central nervous system (CNS) dysfunction after cardio pulmonary bypass represents a continuum from coma and focal stroke to cognitive deficits after surgery. Despite the marked increase in investigation of neuro logic and neurocognitive deficits after cardiac surgery, causative factors fail to predict the majority of the variance in the observed incidence of both early and late neurocognitive decline pointing to some inherent indi vidual susceptibility to injury. The authors' investigative team recently discovered a genetic association be tween late-onset Alzheimer's disease and the apolipo protein E (APOE, gene; apoE, protein) ∈-4 gene. This finding triggered many recent studies that have shown an important role of apoE in the determination of neurologic injury and recovery following a variety of acute ischemic insults including intracerebral hemor rhage, closed-head injury, as well as acute stroke and dementia pugilistica. Most important to the current discussion is the authors' recent report documenting preliminary evidence of an association of APOE4 with neurocognitive decline after cardiac surgery. This re view discusses the authors' hypothesis that the bio chemical products coded by this gene are not available to protect and repair the neurons of the CNS during cardiac surgery resulting in deficits of memory, atten tion, and concentration. Potential mechanisms of apoE's association with acute neurologic injury are discussed including regulation of the inflammatory response. The authors have recently determined that apoE, in vivo, modulates the release of nitric oxide and tumor necro sis factor a. This may compound the autonomic dysreg ulation recently reported in the aging population. The authors' preliminary data associating APOE4 with cogni tive impairment after cardiac surgery support this hy pothesis. The different potential mechanisms of apoE function in neuronal injury and recovery are not mutu ally exclusive, and it is likely that apoE modulates the CNS injury response at several functional levels.

Cardiac Troponin I Concentrations during On-Pump Coronary Artery Surgery

Perioperative myocardial infarction remains a frequent complication after coronary artery bypass grafting, and is associated with a poor prognosis. This retrospective study compared cardiac troponin I concentrations after on-pump bypass grafting in 2 groups of patients: 100 operated on using a single-clamp technique to perform anastomoses, and 80 operated on using a double-clamp technique. Postoperative cardiac troponin I levels were not significantly different between groups. It was concluded that the double-clamp technique did not reduce the incidence of myocardial infarction after elective on-pump coronary artery bypass grafting, and use of a single clamp is safe with no adverse effect on postoperative outcome.

Hyperbaric Oxygen Preconditioning Attenuates Myocardium Ischemia-Reperfusion Injury Through Upregulation of Heme Oxygenase 1 Expression: PI3K/Akt/Nrf2 Pathway Involved

BACKGROUND

With the rise of the burden of ischemic heart disease, both clinical and economic evidence show a desperate need to protect the heart against myocardium ischemia-reperfusion injury-related complications following cardiac surgery or percutaneous coronary intervention. However, there is no effective intervention for myocardium ischemia-reperfusion injury as yet.

METHODS

We pretreated mice with 4 daily 2.0 absolute atmosphere (ATA) hyperbaric oxygen, then observed its effects on heart function parameters and infarct size following in situ ischemia-reperfusion. Multiple oxidative and inflammation products were measured in the myocardium. Next, we investigated the expression of heme oxygenase 1 (HO-1), phosphatidylinositol 3-kinase (PI3K)/serine/threonine protein kinase (Akt) pathway, and NF-E2-related factor 2 (Nrf2) in the presence of myocardium ischemia-reperfusion injury, hyperbaric oxygen preconditioning, and their inhibitors and their effects on heart function parameters.

RESULTS

Hyperbaric oxygen preconditioning ameliorated the cardiac function and histological alterations induced by myocardium ischemia-reperfusion injury, decreased oxidative products and proinflammatory cytokine. Hyperbaric oxygen preconditioning increased expression of HO-1, which was suppressed by PI3K inhibitor LY294002, Nrf2 knockout, and Akt inhibitor triciribine. The expression of Nrf2 was enhanced by hyperbaric oxygen preconditioning, but decreased by LY294002 and triciribine. The Akt was also activated by hyperbaric oxygen preconditioning but suppressed by LY294002. The hemodynamic assays showed that cardiac function was suppressed by LY294002, Nrf2 knockout, and triciribine.

CONCLUSION

These data present a novel signaling mechanism by which hyperbaric oxygen preconditioning protects myocardium ischemia-reperfusion injury via PI3K/Akt/Nrf2-dependent antioxidant defensive system.

Hyperkalemic cardioplegia for adult and pediatric surgery: end of an era?

Despite surgical proficiency and innovation driving low mortality rates in cardiac surgery, the disease severity, comorbidity rate, and operative procedural difficulty have increased. Today's cardiac surgery patient is older, has a "sicker" heart and often presents with multiple comorbidities; a scenario that was relatively rare 20 years ago. The global challenge has been to find new ways to make surgery safer for the patient and more predictable for the surgeon. A confounding factor that may influence clinical outcome is high K(+) cardioplegia. For over 40 years, potassium depolarization has been linked to transmembrane ionic imbalances, arrhythmias and conduction disturbances, vasoconstriction, coronary spasm, contractile stunning, and low output syndrome. Other than inducing rapid electrochemical arrest, high K(+) cardioplegia offers little or no inherent protection to adult or pediatric patients. This review provides a brief history of high K(+) cardioplegia, five areas of increasing concern with prolonged membrane K(+) depolarization, and the basic science and clinical data underpinning a new normokalemic, "polarizing" cardioplegia comprising adenosine and lidocaine (AL) with magnesium (Mg(2+)) (ALM™). We argue that improved cardioprotection, better outcomes, faster recoveries and lower healthcare costs are achievable and, despite the early predictions from the stent industry and cardiology, the "cath lab" may not be the place where the new wave of high-risk morbid patients are best served.

Multimodal brain monitoring reduces major neurologic complications in cardiac surgery

OBJECTIVE

Although adverse neurologic outcomes are common complications of cardiac surgery, intraoperative brain monitoring has not received adequate attention. The aim of the present study was to evaluate the effectiveness of multimodal brain monitoring in the prevention of major brain injury and reducing the duration of mechanical ventilation, intensive care unit, and postoperative hospital stays after cardiac surgery.

DESIGN

A retrospective, observational, controlled study.

SETTING

A single-center regional hospital.

PARTICIPANTS

One thousand seven hundred twenty-one patients who had undergone cardiac surgery with cardiopulmonary bypass from July 2007 to July 2010. One hundred sixty-six patients with multimodal brain monitoring and a control group without brain monitoring (N = 1,555) were compared retrospectively.

INTERVENTIONS

Multimodal brain monitoring was performed for 166 patients, consisting of intraoperative recordings of somatosensory-evoked potentials, electroencephalography, and transcranial Doppler.

MEASUREMENTS AND MAIN RESULTS

The incidence of major neurologic complications and the duration of mechanical ventilation, intensive care unit, and postoperative hospital stays were considered. Patients with brain monitoring had a significantly lower incidence of perioperative major neurologic complications (0%) than those without monitoring (4.06%, p = 0.01) and required significantly shorter periods of mechanical ventilation (p = 0.001) and intensive care unit stays (p = 0.01) than controls. The length of postoperative hospital stays did not differ significantly between the 2 groups (p = 0.57).

CONCLUSIONS

This preliminary study suggests that multimodal brain monitoring can reduce the incidence of neurologic complications as well as hospital costs associated with post-cardiac surgery patient care. Furthermore, intraoperative brain monitoring provides useful information about brain functioning, blood flow velocity, and metabolism, which may guide the anesthesiologist during surgery.

The Impact of Adenosine Fast Induction of Myocardial Arrest during CABG on Myocardial Expression of Apoptosis-Regulating Genes Bax and Bcl-2

Background. We studied the effect of fast induction of cardiac arrest with denosine on myocardial bax and bcl-2 expression. Methods and Results. 40 elective CABG patients were allocated into two groups. The adenosine group (n = 20) received 250 μg/kg adenosine into the aortic root followed by blood potassium cardioplegia. The control group received potassium cardioplegia in blood. Bcl-2 and bax were measured. Bax was reduced in the postoperative biopsies (1.38 versus 0.47, P = .002) in the control group. Bcl-2 showed a reducing tendency (0.14 versus 0.085, P = .07). After the adenosine treatment, the expression of both bax (0.52 versus 0.59, P = .4) and bcl-2 (0.104 versus 0.107, P = .4) remained unaltered after the operation. Conclusion. Open heart surgery is associated with rapid reduction in the expression of apoptosis regulating genes bax and bcl-2. Fast Adenosine induction abolished changes in their expression.

Clevidipine: an ultra short-acting calcium channel antagonist for acute hypertension

OBJECTIVE

To review the safety, efficacy, and pharmacologic characteristics of clevidipine, a new ultra short-acting intravenous antihypertensive agent for the treatment of moderate-to-severe hypertension.

DATA SOURCES

A literature search was conducted through MEDLINE (1966-March 2009), International Pharmaceutical Abstracts (1970-March 2009), and EMBASE (1988-March 2009) using the search terms clevidipine, H324/38, hypertension, and hypertensive crisis.

STUDY SELECTION AND DATA EXTRACTION

Available studies, abstracts, and review articles published in English that evaluated the pharmacology, pharmacokinetics, safety, and clinical efficacy of clevidipine were reviewed and critically evaluated.

DATA SYNTHESIS

Clevidipine is a new third-generation dihydropyridine calcium-channel blocker available for intravenous management of moderate-to-severe hypertension. Clevidipine is an ultra short-acting, selective arteriolar vasodilator that acts similar to other L-type dihydropyridine calcium-channel blockers by inhibiting influx of extracellular calcium into the vascular smooth muscle. Its safety and efficacy have been primarily evaluated in the perioperative setting in patients undergoing cardiac surgery requiring management of elevated blood pressure. In comparison to most other intravenous antihypertensives, clevidipine has a rapid onset of action, is ultra short-acting, easily titratable with a predictable dose response, and is void of drug-drug interactions and need for dose adjustment in patients with hepatic or renal insufficiency, thus making it a valuable antihypertensive in both the intraoperative and critical care settings. In clinical trials, clevidipine was well tolerated at infusion rates from 2-32 mg per hour, for up to 72 hours.

CONCLUSIONS

Clevidipine is the first intravenous antihypertensive approved by the Food and Drug Administration in nearly a decade. Based on available published clinical trials, clevidipine appears to be safe and effective in the acute management of moderate-to-severe elevations in blood pressure and a viable alternative to other agents such as nitroglycerin, sodium nitroprusside, and nicardipine.

Pulse pressure and risk of adverse outcome in coronary bypass surgery

BACKGROUND

Among ambulatory patients, an increase in pulse pressure (PP) is a well-established determinant of vascular risk. The relationship of PP and acute perioperative vascular outcome among patients having coronary artery bypass graft (CABG) surgery is less well known.

METHODS

We conducted a prospective observational study involving 5436 patients having elective CABG surgery requiring cardiopulmonary bypass. Of these, 4801 met final inclusion criteria. Comprehensive data were captured for medical history, intraoperative and postoperative physiologic and laboratory measures, diagnostic testing, and clinical events. The relationship between preoperative hypertension (systolic, diastolic, PP) and ischemic cardiac and cerebral outcomes and death was assessed using multivariable logistic regression; P<0.05 was considered significant.

RESULTS

Nine hundred and seventeen patients (19.1%) had fatal and nonfatal vascular complications, including 146 patients (3.0%) with cerebral and 715 patients (14.9%) with cardiac events. In-hospital mortality occurred in 147 patients (3.1%). Among all blood pressure variables measured preoperatively, PP was most strongly associated with an increased risk of postoperative complications. PP increments of 10 mm Hg (above a threshold of 40 mm Hg) were associated with an increased risk of cerebral events (adjusted odds ratio: 1.12; 95% CI [1.002-1.28]; P=0.026). The incidence of a cerebral event and/or death from neurologic complications nearly doubled for patients with PP>80 mm Hg versus<or=80 mm Hg (5.5% vs 2.8%; P=0.004). PP more than 80 mm Hg was also found to be associated with cardiac complications, increasing the incidence of congestive heart failure by 52%, and death from cardiac cause by nearly 100% (P=0.003 and 0.006, respectively).

CONCLUSION

An increase in PP was independently and significantly associated with greater fatal and nonfatal adverse cerebral and cardiac outcomes in patients having CABG surgery. These findings highlight the associated risks of preoperative PP on acute postoperative vascular outcomes.

Aprotinin in Cardiac Surgery: A Review of Conventional and Novel Mechanisms of Action

Induction of the coagulation and inflammatory cascades can cause multiorgan dysfunction after cardiopulmonary bypass (CPB). In light of these observations, strategies that can stabilize the coagulation process as well as attenuate the inflammatory response during and after cardiac surgery are important. Aprotinin has effects on hemostasis. In addition, aprotinin may exert multiple biologically relevant effects in the context of cardiac surgery and CPB. For example, it decreases neutrophil and macrophage activation and chemotaxis, attenuates release and activation of proinflammatory cytokines, and reduces oxidative stress. Despite these perceived benefits, the routine use of aprotinin in cardiac surgery with CPB has been called into question. In this review, we examined this controversial drug by discussing the classical and novel pathways in which aprotinin may be operative in the context of cardiac surgery.

Effects of pyridoxal-5′-phosphate (MC-1) in patients undergoing high-risk coronary artery bypass surgery: Results of the MEND-CABG randomized study

OBJECTIVE

Coronary artery bypass graft surgery remains associated with significant postoperative cardiovascular morbidity and mortality in high-risk patients. MC-1 (pyridoxal-5'-phosphate monohydrate) inhibits purinergic receptors and intracellular influx of Ca2+, thereby reducing cellular injury during experimental ischemia and reperfusion. The MEND-CABG trial tested the hypothesis that MC-1 reduces cardiovascular morbidity and mortality after coronary artery bypass graft.

METHODS

In a phase 2, double-blinded, placebo-controlled study, 901 patients scheduled for coronary artery bypass graft surgery with cardiopulmonary bypass and at high risk for subsequent cardiac or neurologic complications were randomly assigned to receive oral MC-1 (250 mg or 750 mg/d once daily) or placebo beginning 3 to 10 hours prior to surgery and continued to postoperative day 30.

RESULTS

At 30 days, MC-1 250 mg (compared with placebo) reduced the composite of death, nonfatal cerebral infarction, and nonfatal myocardial infarction by 14.0% (P = .3124) with peak creatinine kinase-myocardial band > or =50 ng/mL (prespecified primary end point); 32.3% (P = .0349) with peak creatinine kinase-myocardial band > or =70 ng/mL; and 37.2% (P = .0283) with peak creatinine kinase-myocardial band > or =100 ng/mL. Myocardial infarctions with peak creatinine kinase-myocardial band> or =100 ng/mL were reduced by 47.2% in the MC-1 250-mg group versus placebo (P = .0083). Greater efficacy was demonstrated with 250 mg than with the 750-mg dose of MC-1.

CONCLUSIONS

In high-risk patients undergoing coronary artery bypass graft, treatment with MC-1 did not significantly affect the prespecified primary end point but was associated with a significant reduction in perioperative myocardial infarction with creatinine kinase-myocardial band > or =100 ng/mL. A larger, well-powered trial is needed to evaluate the cardioprotective effects of MC-1.

Coronary artery bypass graft surgery—care globalization: The impact of national care on fatal and nonfatal outcome

OBJECTIVE

In an international, prospective, observational study, we contrasted adverse vascular outcomes among four countries and then assessed practice pattern differences that may have contributed to these outcomes.

METHODS

A total of 5065 patients undergoing coronary artery bypass graft surgery were analyzed at 70 international medical centers, and from this pool, 3180 patients from the 4 highest enrolling countries were selected. Fatal and nonfatal postoperative ischemic complications related to the heart, brain, kidney, and gastrointestinal tract were assessed by blinded investigators.

RESULTS

In-hospital mortality was 1.5% (9/619) in the United Kingdom, 2.0% (9/444) in Canada, 2.7% (34/1283) in the United States, and 3.8% (32/834) in Germany (P = .03). The rates of the composite outcome (morbidity and mortality) were 12% in the United Kingdom, 16% in Canada, 18% in the United States, and 24% in Germany (P < .001). After adjustment for difference in case-mix (using the European System for Cardiac Operative Risk Evaluation) and practice, country was not an independent predictor for mortality. However, there was an independent effect of country on composite outcome. The practices that were associated with adverse outcomes were the intraoperative use of aprotinin, intraoperative transfusion of fresh-frozen plasma or platelets, lack of use of early postoperative aspirin, and use of postoperative heparin.

CONCLUSIONS

Significant between-country differences in perioperative outcome exist and appear to be related to hematologic practices, including administration of antifibrinolytics, fresh-frozen plasma, platelets, heparin, and aspirin. Understanding the mechanisms for these observations and selection of practices associated with improved outcomes may result in significant patient benefit.

Strength of evidence for perioperative use of statins to reduce cardiovascular risk: systematic review of controlled studies

OBJECTIVE

To determine the strength of evidence underlying recommendations for use of statins during the perioperative period to reduce the risk of cardiovascular events.

DESIGN

Systematic review of studies with concurrent control groups.

DATA SOURCES

Four electronic databases, the references of identified studies, international experts on perioperative medicine, and the authors of the primary studies. Review methods Two reviewers independently extracted data from studies that reported acute coronary syndromes or mortality in patients receiving or not receiving statins during the perioperative period.

MAIN OUTCOME MEASURE

Random effects summary odds ratios for death or acute coronary syndrome during the perioperative period.

RESULTS

18 studies--two randomised trials (n=177), 15 cohort studies (n=799,632), and one case-control study (n=480)--assessed whether statins provide perioperative cardiovascular protection; 12 studies enrolled patients undergoing non-cardiac vascular surgery, four enrolled patients undergoing coronary bypass surgery, and two enrolled patients undergoing various surgical procedures. In the randomised trials the summary odds ratio for death or acute coronary syndrome during the perioperative period with statin use was 0.26 (95% confidence interval 0.07 to 0.99) and the summary odds ratio in the cohort studies was 0.70 (0.57 to 0.87). Although the pooled cohort data provided a statistically significant result, statins were not randomly allocated, results in retrospective studies were larger (odds ratio 0.65, 0.50 to 0.84) than those in the prospective cohorts (0.91, 0.65 to 1.27), and dose, duration, and safety of statin use was not reported.

CONCLUSION

The evidence base for routine administration of statins to reduce perioperative cardiovascular risk is inadequate.

Balancing the benefit and risk of oral antiplatelet agents in coronary artery bypass surgery

Concern about possible hemorrhagic complications arising from use of oral antiplatelet agents in immediate proximity to coronary artery bypass graft (CABG) surgery leads many clinicians to avoid or discontinue these agents preoperatively. Recent evidence suggests that aspirin and clopidogrel can be used with relative safety in the preoperative period; dual antiplatelet therapy in the 5 days immediately preceding CABG surgery results in a moderate and variable increase in the risk of procedural bleeding. This modest hemorrhagic risk may be acceptable, given the clinical benefits of sustained antiplatelet therapy in preventing graft occlusion and ischemic complications pre- and post-CABG. Because the bleeding risk with aspirin is dose dependent, use of a low dose is preferred post-CABG.

Hypertension: a new look at an old problem

PURPOSE OF REVIEW

This review reports the specific impact that hypertension, identified by its component subtype classification, has on perioperative outcomes. Most importantly, we review the risk of systolic hypertension and pulse pressure hypertension independent of elevated diastolic blood pressure on patients undergoing cardiac surgery.

RECENT FINDINGS

Systemic hypertension is identified as a major risk factor for cardiovascular morbidity in most larger population-based studies. Nearly a third of the population in the United States has or will have some form of hypertension disease, with many under-diagnosed or under-treated. Classification of hypertensive subtypes has been well recognized as an important component for risk stratification in the ambulatory population in recent years, but remains poorly recognized in the surgical setting. We present recent data unveiling the importance of pulse pressure above that of systolic and diastolic pressures.

SUMMARY

The evidence is compelling that wide pulse pressure hypertension is a strong and an independent predictor of adverse perioperative renal, cerebral and mortality outcomes. We discuss the physiology for this important novel observation in an acute surgical patient population and provide an explanation.

Preoperative statin treatment is associated with reduced postoperative mortality and morbidity in patients undergoing cardiac surgery: An 8-year retrospective cohort study

BACKGROUND

Cardiac surgical procedures can be associated with significant morbidity and mortality. Recently, it has been recognized that statins might induce multiple biologic effects independent of lipid lowering that could potentially ameliorate adverse surgical outcomes. Accordingly, this study tested the central hypothesis that pretreatment with statins before cardiac surgery would reduce adverse postoperative surgical outcomes.

METHODS

Demographic and outcomes data were collected retrospectively for 3829 patients admitted for planned cardiac surgery between February 1994 and December 2002. Statin pretreatment occurred in 1044 patients who were comparable with non-statin-pretreated (n = 2785) patients with regard to sex, race, and age. Primary outcomes examined included postoperative mortality (30-day) and a composite morbidity variable.

RESULTS

The odds of experiencing 30-day mortality and morbidity were significantly less in the statin-pretreated group, with unadjusted odds ratios of 0.43 (95% confidence interval [CI], 0.28-0.66) and 0.72 (95% CI, 0.61-0.86), respectively. Risk-adjusted odds ratios for mortality and morbidity were 0.55 (95% CI, 0.32-0.93) and 0.76 (95% CI, 0.62-0.94), respectively, by using a logistic regression model and 0.51 (95% CI, 0.27-0.94) and 0.71 (95% CI, 0.55-0.92), respectively, in the propensity-matched model, demonstrating significant reductions in 30-day morbidity and mortality. In a subsample of patients undergoing valve-only surgery (n = 716), fewer valve-only patients treated with statins experienced mortality, although these results were not statistically significant (1.96% vs 7.5%).

CONCLUSIONS

These findings indicate that statin pretreatment before cardiac surgery confers a protective effect with respect to postoperative outcomes.

Attenuation of ischemia-reperfusion injury in a canine model of autologous renal transplantation

BACKGROUND

This study examined the potential therapeutic effects of a combination therapy consisting of 5-aminoimidazole-4-carboxamide-1-beta-D-ribonucleoside (AICAR) and N-acetyl cysteine (NAC) to attenuate ischemia-reperfusion (I/R) injury in a canine model of autologous renal transplantation.

METHODS

Male mongrel dogs (15-20 kg) underwent left nephrectomy followed by flushing and static preservation of the kidney in University of Wisconsin (UW) solution for 48 hr. The treatment group received AICAR (50 mg/kg) plus NAC (100 mg/kg) intravenously before the left nephrectomy. The compounds were added to the UW solution as well. All dogs underwent right nephrectomy 48 hr later followed by autotransplantation of the preserved left kidney. Treated dogs received a second dose of AICAR and NAC before implantation of the renal autograft.

RESULTS

The treated dogs had excellent urine output posttransplant, with peak serum creatinine of 7.26 mg/dL on postoperative day (POD) 3 that normalized after 14 days. The control group were anuric and developed clinical symptoms of uremia on POD 1. Morphologic evaluation supported the protective effects of combination therapy. Immunohistochemical analysis revealed decrease of tumor necrosis factor-alpha, interferon-gamma, and inducible nitric oxide synthase; and TUNEL assay showed decreased apoptosis in the treated group.

CONCLUSIONS

Combination therapy with AICAR and NAC attenuates renal I/R injury and improves the outcome of the transplanted kidney after prolonged cold preservation.

Effects of the angiotensin II subtype 1 receptor antagonist losartan on functional recovery of isolated rat hearts undergoing global myocardial ischemia-reperfusion

STUDY OBJECTIVE

To investigate the effects of the angiotensin II subtype 1 receptor (AT1R) antagonist losartan on functional recovery of isolated rat hearts undergoing global myocardial ischemia-reperfusion compared with myocardial protective effects of ischemic preconditioning.

DESIGN

Ex vivo experiment using isolated perfused rat heart.

SETTING

Academic laboratory.

INTERVENTION

Hearts from Sprague-Dawley rats were perfused with oxygenated Krebs-Henseleit buffer and randomized to one of four groups: time control, vehicle, ischemic preconditioning, or losartan.

MEASUREMENTS AND MAIN RESULTS

After randomization, hearts underwent 30 minutes of global ischemia followed by 30 minutes of reperfusion. Changes in end-diastolic pressure (EDP), left ventricular developed pressure (LVDP), and infarct size were examined between treatment groups by two-way analysis of variance with repeated measures. Cardiac angiotensin II receptor (ATR) density and infarct size were measured in control hearts and in a subgroup of hearts exposed to ischemia-reperfusion injury. Total ATR density and percentage of myocardial AT1R were increased in hearts exposed to ischemia-reperfusion. Myocardial ischemia-reperfusion injury resulted in a 56% reduction in LVDP from baseline in hearts randomized to vehicle. However, it declined by only 22% and 28% in hearts randomized to ischemic preconditioning and losartan, respectively. Compared with vehicle, both ischemic preconditioning and losartan decreased EDP (ischemic preconditioning 39 +/- 3 mm Hg, losartan 54 +/- 5 mm Hg, vs vehicle 78 +/- 8 mm Hg), and reduced infarct size (ischemic preconditioning 9%, losartan 12%, vs vehicle 36%).

CONCLUSION

Treatment of isolated rat hearts with losartan before ischemia-reperfusion injury resulted in significant cardioprotection similar to that observed with ischemic preconditioning.

Perioperative myocardial ischemia reperfusion injury

Myocardial I-R injury contributes to adverse cardiovascular outcomes after cardiac surgery. The pathogenesis of I-R injury is complex and involves the activation, coordination, and amplification of several systemic and local proinflammatory pathways (Fig. 4). Treatment and prevention of perioperative morbidity associated with myocardial I-R will ultimately require a multifocal approach. Combining preoperative risk stratification (co-morbidity and surgical complexity), minimizing initiating factors predisposing to SIRS, limiting ischemia duration, and administering appropriate immunotherapy directed toward systemic and local proinflammatory mediators of I-R injury, should all be considered. In addition, the role of the genetic-environmental interactions in the pathogenesis of cardiovascular disease is also being examined. Thus, in the near future, preoperative screening for polymorphisms of certain inflammatory and coagulation genes should inevitably help reduce morbidity by permitting the identification of high-risk cardiac surgical patients and introducing the opportunity for gene therapy or pharmacogenetic intervention [42,64].

Rehabilitation of postcardiac surgery stroke patients. Progress, outcomes, and comparisons with other stroke patients

OBJECTIVE

To examine the demographics, progress, and functional outcomes of all postcardiac surgery stroke patients admitted to the rehabilitation unit of an acute, tertiary general hospital over a 5-yr period and to compare this cohort with an age-matched control group of other stroke patients admitted during the same period.

DESIGN

A retrospective chart review of 47 postcardiac surgery stroke and a matched control group of other stroke patients admitted to the rehabilitation unit.

RESULTS

The mean age of the postcardiac surgery stroke patients was 70.80 +/- 8.37 yr, with 60% of patients being male. Their average length of stay on the rehabilitation unit was 15.64 +/- 11.96 days. Mean admit FIM total score was 65.64 +/- 16.33, with a discharge FIM total score of 86.77 +/- 18.93. Mean admit FIM motor score was 41.47 +/- 9.45, with a discharge FIM motor of 60.74 +/- 13.20. The other stroke group had significantly greater admit FIM total (P = 0.03), admit motor (P = 0.001), and discharge motor (P = 0.025) scores. FIM efficiency and motor and cognitive gains were comparable between the two groups. Length of stay on the rehabilitation unit was approximately 2 days less (P = 0.224) for the other stroke cohort. Ultimately, 39 (83%) of the postcardiac surgery stroke patients were discharged to the community compared with 45 (96%) of the other stroke patients (P = 0.19).

CONCLUSIONS

The majority of postcardiac surgery stroke patients successfully completed a comprehensive inpatient rehabilitation program. They had lower admit FIM total scores and admit and discharge FIM motor scores than the other stroke group and were almost as likely to ultimately return to the community.

Intracellular sodium hydrogen exchange inhibition and clinical myocardial protection

Although the mechanisms underlying ischemia/reperfusion injury remain elusive, evidence supports the etiologic role of intracellular calcium overload and oxidative stress induced by reactive oxygen species. Activation of the sodium hydrogen exchanger (NHE) is associated with intracellular calcium accumulation. Inhibition of the NHE-1 isoform may attenuate the consequences of this injury. Although there is strong preclinical and early clinical evidence that NHE inhibitors may be cardioprotective, definitive proof of this concept in humans awaits the results of ongoing clinical trials.

The role of sodium-hydrogen ion exchange in patients undergoing coronary artery bypass grafting

Sodium-hydrogen ion exchange (NHE) is one of the principal mechanisms of restoring intracellular pH following ischemia and reperfusion. However, up-regulation of the NHE process results in a compensatory increase in the activity of the sodium-calcium exchanger. Intracellular hypercalcemia, resulting from the exchange of sodium for calcium, precipitates myocardial stunning and cell death. It has been postulated that NHE inhibition can protect the ischemic/reperfused myocardium, and preclinical studies have uniformly supported this concept. The Guard During Ischemia Against Necrosis (GUARDIAN) trial suggested benefits of NHE inhibition in subjects undergoing coronary artery bypass grafting (CABG). The sodium-hydrogen eXchange inhibition to Prevent coronary Events in acute cardiac conDITIONs (EXPEDITION) trial will further explore the use of cariporide in a randomized, controlled trial of CABG subjects at risk of myocardial necrosis.

Therapeutic potential of targeting the complement cascade in critical care medicine

Caring for the critical care patient involves many different areas of clinical expertise and serves a diverse patient population. Novel therapeutics for the critically ill must be approached with caution, because the underlying molecular mechanisms of the disease process for several commonly seen types of patients (i.e., sepsis, shock, ischemia/reperfusion) are not fully understood. A potentially new and advancing area of therapeutics that may hold promise for the critically ill is inhibition of the complement system. Various novel complement inhibitors are being developed and several are in clinical trials. The advancement of this novel area of therapeutics may one day aid the clinician by providing several different complement inhibitors/antagonists for controlling complement activation or its biologically active mediators.

Aspirin and mortality from coronary bypass surgery

BACKGROUND

There is no therapy known to reduce the risk of complications or death after coronary bypass surgery. Because platelet activation constitutes a pivotal mechanism for injury in patients with atherosclerosis, we assessed whether early treatment with aspirin could improve survival after coronary bypass surgery.

METHODS

At 70 centers in 17 countries, we prospectively studied 5065 patients undergoing coronary bypass surgery, of whom 5022 survived the first 48 hours after surgery. We gathered data on 7500 variables per patient and adjudicated outcomes centrally. The primary focus was to discern the relation between early aspirin use and fatal and nonfatal outcomes.

RESULTS

During hospitalization, 164 patients died (3.2 percent), and 812 others (16.0 percent) had nonfatal cardiac, cerebral, renal, or gastrointestinal ischemic complications. Among patients who received aspirin (up to 650 mg) within 48 hours after revascularization, subsequent mortality was 1.3 percent (40 of 2999 patients), as compared with 4.0 percent among those who did not receive aspirin during this period (81 of 2023, P<0.001). Aspirin therapy was associated with a 48 percent reduction in the incidence of myocardial infarction (2.8 percent vs. 5.4 percent, P<0.001), a 50 percent reduction in the incidence of stroke (1.3 percent vs. 2.6 percent, P=0.01), a 74 percent reduction in the incidence of renal failure (0.9 percent vs. 3.4 percent, P<0.001), and a 62 percent reduction in the incidence of bowel infarction (0.3 percent vs. 0.8 percent, P=0.01). Multivariate analysis showed that no other factor or medication was independently associated with reduced rates of these outcomes and that the risk of hemorrhage, gastritis, infection, or impaired wound healing was not increased with aspirin use (odds ratio for these adverse events, 0.63; 95 percent confidence interval, 0.54 to 0.74).

CONCLUSIONS

Early use of aspirin after coronary bypass surgery is safe and is associated with a reduced risk of death and ischemic complications involving the heart, brain, kidneys, and gastrointestinal tract.

Cardiac troponin I: its contribution to the diagnosis of perioperative myocardial infarction and various complications of cardiac surgery

OBJECTIVE

To study the value of assaying cardiac troponin I (cTnI) for the early diagnosis of perioperative myocardial infarction (PMI) and various complications of cardiac surgery.

DESIGN

A prospective observational clinical study.

SETTING

Biochemical laboratory, anesthesia, and cardiac surgery department of Hôpital Broussais.

PATIENTS

Two hundred and sixty consecutive patients undergoing cardiac surgery.

INTERVENTIONS

All patients underwent coronary artery bypass grafting and/or valvular surgery under extracorporeal circulation. Per-operative and postoperative follow-up consisted of electrocardiogram, echocardiography (mainly by the transesophageal approach), and serial determinations of biochemical markers such as creatinine kinase-MB isoenzyme (CK-MB) and cTnI. PMI, new ST segment changes, and ventricular arrhythmias were considered postoperative adverse cardiac outcome.

MEASUREMENTS AND MAIN RESULTS

CTnI was measured before cardiopulmonary bypass (T0) and 12 and 24 hrs after (T12, T24). CK-MB was measured on arrival in the intensive care unit and on the first postoperative day (D1). Patients were divided into three groups according to the type of surgery: coronary artery bypass graft (CABG), valvular surgery (VS), or both procedures. The plasma CK-MB and cTnI concentrations were high in all patients after extracorporeal circulation because of aortic clamping or cardioplegia. The CK-MB and cTnI values were higher in the VS group than in the CABG group. Values peaked at T12 and fell by T24, except when PMI occurred. Eight patients developed a PMI. Patients with PMI had significantly higher cTnI levels at T12 and T24, and higher CK-MB values at D1 than patients without PMI. Cutoff values of cTnI for diagnosing PMI were >19 microg/L at T12 with 100% sensitivity and 73% specificity, and >36 microg/L at T24, with 100% sensitivity and 93% specificity. Lower cTnI values were highly suggestive of the absence of PMI after CABG and/or VS. Other complications such as ST segment changes, ventricular arrhythmias and cardiac failure were indicated by high cTnI levels at T12 and T24. Myocardial protective measures were associated with a nonsignificant increase in cTnI values.

CONCLUSIONS

CTnI is more sensitive and specific than CK-MB for diagnosing PMI and other forms of heart failure after cardiac surgery.

An analysis of limb-threatening lower extremity wound complications after 1090 consecutive coronary artery bypass procedures

The objective of this study was to examine and characterize limb-threatening lower extremity wound or soft tissue complications after coronary artery bypass (CABG) and determine risk factors for their cause. While minor wound problems of the leg after CABG are not uncommon, serious limb-threatening complications, though less frequent, do occur and are often de-emphasized in the surgical literature. A review of 1090 consecutive CABG procedures performed from January 1, 1995 through December 31, 1995 was instituted, which screened for limb-threatening lower extremity wound or soft tissue complications defined as wounds that: required additional surgery for treatment; prolonged the length of stay; or which required lengthy home health nursing for treatment. Minor lymph leaks, leg swelling, infections or wound problems treated as an outpatient were excluded. Of 1090 patients, 54 (5.0%) experienced a limb-threatening lower extremity complication. Complications were categorized as vein harvest incision non-healing (n = 36, 66.7%), decubitus ulceration (n = 11, 20.4%), forefoot ischemia/embolization (n = 10, 18.5%), groin hematoma/abscess (n = 6, 11.1%), severe cellulitis (n = 3, 5.6%), or a combination (n = 12, 22.2%). Statistically significant risk factors by univariate and bivariate analysis for a complication included older age (68 years vs 62 years, p = 0.007), female sex (57% vs 28%, p < 0.001), diabetes (57% vs 33%, p = 0.005) and longer pump time (129 min vs 114 min, p = 0.009). These complications necessitated five major lower extremity amputations and nine revascularization procedures. Chronic lower extremity ischemia from peripheral vascular disease (PVD) was a major contributing factor for the development of wounds in at least 23 (42.6%) of these patients, though suspected in only 10 (43.5%) preoperatively. A non-healing vein harvest incision below the knee of a patient retrospectively found to have inadequate distal circulation for healing occurred in 17 (31.5%) of the total 54 cases. It was concluded that non-healing vein incisions, decubitus ulcers and forefoot ischemic lesions frequently occurring in older diabetic females with undetected pre-existing PVD, comprise the majority of limb-threatening leg complications after CABG. Nearly one-third of the complications may have been avoided had the vein harvest incision not been made at the ankle of a patient with unappreciated PVD.

Intraoperative physiologic variables and outcome in cardiac surgery: Part II. Neurologic outcome

BACKGROUND

The impact of alterable physiologic variables on neurologic outcome after coronary artery bypass grafting procedures is unknown. The purpose of this study was to determine whether minimum intraoperative hematocrit, maximum glucose concentration, or mean arterial pressure during cardiopulmonary bypass influences risk-adjusted neurologic outcome after coronary artery bypass grafting.

METHODS

Outcome data from 2,862 patients undergoing coronary artery bypass grafting were merged with intraoperative physiologic data. A preoperative stroke risk index was calculated for each patient. Variables found significant by univariate logistic regression were tested in a multivariable model to determine association with outcome.

RESULTS

The incidence of stroke or coma in the study population was 1.3%. After controlling for stroke risk and bypass time, only an index of low mean arterial pressure during bypass retained a significant inverse association with outcome (p = 0.0304).

CONCLUSIONS

This study found no evidence that glucose concentration or minimum hematocrit are associated with major adverse neurologic outcome. The association between lower pressure during bypass and decreased incidence of stroke or coma persisted in all risk groups. This points to mechanisms other than hypoperfusion as the primary cause of neurologic injury associated with cardiac surgery.

Pharmacology and biological efficacy of a recombinant, humanized, single-chain antibody C5 complement inhibitor in patients undergoing coronary artery bypass graft surgery with cardiopulmonary bypass

BACKGROUND

Cardiopulmonary bypass (CPB) induces a systemic inflammatory response that causes substantial clinical morbidity. Activation of complement during CPB contributes significantly to this inflammatory process. We examined the capability of a novel therapeutic complement inhibitor to prevent pathological complement activation and tissue injury in patients undergoing CPB.

METHODS AND RESULTS

A humanized, recombinant, single-chain antibody specific for human C5, h5G1.1-scFv, was intravenously administered in 1 of 4 doses ranging from 0.2 to 2.0 mg/kg before CPB. h5G1.1-scFv was found to be safe and well tolerated. Pharmacokinetic analysis revealed a sustained half-life from 7.0 to 14.5 hours. Pharmacodynamic analysis demonstrated significant dose-dependent inhibition of complement hemolytic activity for up to 14 hours at 2 mg/kg. The generation of proinflammatory complement byproducts (sC5b-9) was effectively inhibited in a dose-dependent fashion. Leukocyte activation, as measured by surface expression of CD11b, was reduced (P<0.05) in patients who received 1 and 2 mg/kg. There was a 40% reduction in myocardial injury (creatine kinase-MB release, P=0.05) in patients who received 2 mg/kg. Sequential Mini-Mental State Examinations (MMSE) demonstrated an 80% reduction in new cognitive deficits (P<0.05) in patients treated with 2 mg/kg. Finally, there was a 1-U reduction in postoperative blood loss (P<0. 05) in patients who received 1 or 2 mg/kg.

CONCLUSIONS

A single-chain antibody specific for human C5 is a safe and effective inhibitor of pathological complement activation in patients undergoing CPB. In addition to significantly reducing sC5b-9 formation and leukocyte CD11b expression, C5 inhibition significantly attenuates postoperative myocardial injury, cognitive deficits, and blood loss. These data suggest that C5 inhibition may represent a novel therapeutic strategy for preventing complement-mediated inflammation and tissue injury.

Cellular and molecular therapeutic targets for treatment of contractile dysfunction after cardioplegic arrest

Transient left ventricular (LV) dysfunction can occur after hypothermic hyperkalemic cardioplegic arrest. This laboratory has developed an isolated LV myocyte system of simulated cardioplegic arrest and rewarming in order to examine cellular and molecular events that may contribute to the LV dysfunction after cardioplegic arrest. Contractile function was examined using high-speed video microscopy after reperfusion and rewarming. After cardioplegic arrest and reperfusion, indices of myocyte contractility were reduced by over 40% from normothermic control values. The capacity of the myocyte to respond to an inotropic stimulus was examined through beta-adrenergic receptor stimulation with isoproterenol. After cardioplegic arrest, the contractile response to isoproterenol was reduced by over 50% from normothermic values. The next series of studies focused upon preventing these changes in myocyte contractile processes after cardioplegic arrest. First, the cardioplegic solutions were augmented with adenosine or an ATP-sensitive potassium channel opener, aprikalim. Both adenosine and aprikalim augmentation significantly improved myocyte function compared with cardioplegia alone values. A potential intracellular mechanism for the protective effects of either adenosine or the ATP-sensitive potassium channel is the activation of protein kinase C (PKC). A brief period of PKC activation before cardioplegic arrest provided protective effects on myocyte contractility with subsequent reperfusion and rewarming. In another set of studies, the potential protective effects of the active form of thyroid hormone (T3) were examined. In myocytes pretreated with T3, myocyte contractile function and beta-adrenergic responsiveness were significantly improved after hypothermic cardioplegic arrest and rewarming. Thus, endogenous means of providing improved myocardial protection during prolonged cardioplegic arrest can be achieved through a brief period of PKC activation or pretreatment with T3. Future studies, which more carefully deduce the basis for these pretreatment effects, will likely yield novel methods by which to protect myocyte contractile processes during cardioplegic arrest.

Pharmacologic enhancement of tolerance to ischemic cardiac stress using monophosphoryl lipid A. A comparison with antecedent ischemia

In comparison with ischemic preconditioning, MLA-mediated cardioprotection seems to show numerous common features. Like ischemia, MLA induces a first and second window (biphasic profile) of heightened tolerance to ischemia. As with delayed ischemic preconditioning, MLA protects against infarction, stunning, and arrhythmias associated with ischemia-reperfusion. In contrast with acute ischemic preconditioning, MLA reduces infarction and stunning. A role has been demonstrated for nitric oxide synthase and KATP channel activation in the mechanism of delayed preconditioning induced by ischemia and by MLA. Regarding acute preconditioning, kinase and KATP channel activation have been implicated as involved in the mechanism of ischemic preconditioning and also in MLA cardioprotection. Use of MLA or related compounds as cardioprotectants may represent a method for inducing acute tolerance to ischemia-reperfusion injury manifested as infarction or stunning, with the added benefit of a sustained delayed cardioprotective state being achieved.

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

BACKGROUND AND PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Complete thromboendarterectomy of the calcified ascending aorta and aortic arch

BACKGROUND

Arteriosclerotic plaques of the ascending aorta and transverse arch increase the operative risk of cardiac operations and are strong predictors for late cerebrovascular events.

METHODS

Twenty-two patients, mean age 68 +/- 6 years (range, 55 to 77 years), with grade IV + V plaques of the ascending aorta and transverse arch underwent coronary artery bypass grafting (n = 21) and aortic valve replacement (n = 8). Cerebrovascular emboli from unknown sources were found preoperatively in 8 patients (36%). All were in sinus rhythm. Complete thromboendarterectomy of the ascending aorta and transverse arch was performed during hypothermic circulatory arrest. After 21 +/- 12 months (range, 4 to 44 months), magnetic resonance imaging and transthoracic echocardiography of endarterectomized vessels was performed.

RESULTS

There was one perioperative death (4.5%), one early (4.5%), and one late (4.7%) adverse neurologic event. Follow-up examinations revealed normal diameters of the endarterectomized aorta.

CONCLUSIONS

For patients with grade IV + V plaques, thromboendarterectomy of the ascending aorta and transverse arch can be performed with an acceptable surgical risk and a low recurrence rate for cerebrovascular events. Dilatation of the endarterectomized aorta was not observed.

Perioperative Stroke, Encephalopathy, and Central Nervous System Dysfunction

The leading cause of mortality in adult populations throughout the world is atherosclerosis, which results in cardiovascular and cerebrovascular complications and consumes substantive health care resources. The impact of atherosclerosis on patients undergoing surgery is also considerable, given the multiple stresses occurring during, and especially following, the surgical procedures, thereby precipitating vascular morbidity. Perioperative cerebrovascular morbidity and mortality occur in approximately 10% of the 600,000 patients who undergo cardiac surgery annually, consuming approximately $13 billion, which is expended on in-hospital, intensive care unit (ICU), and long-term specialized care for these neurological complications of stroke, encephalopathy, and cognitive dysfunction. Furthermore, risk of these outcomes will continue to increase as the surgical population ages. Principal among the etiologies of focal stroke and encephalopathy appear to be perioperative hypotension and precipitation of macroemboli and microemboli. As a result, new detection techniques for these events have been instituted, including (1) continuous hemodynamic monitoring, for detection of hypotensive episodes; (2) transesophageal echocardiography, for detection of aortic atherosclerosis, a potential source for emboli; and (3) transcranial Doppler sonography, for detection of cerebral emboli, as well as determination of cerebral blood flow. Recent large-scale multicenter studies have identified risk factors and indices for perioperative central nervous system (CNS) morbidity. Regarding therapy, a number of pharmacological approaches are currently under consideration; principal among these approaches are agents that can modulate the excitotoxic response, including glutamate receptor antagonists (NMDA, AMPA, metabotrophic), calcium channel blockers, free radical scavengers, and agents that modify the inflammatory white cell response. Although a number of laboratory, animal, and smaller clinical trials have been conducted, only one large-scale multicenter program to date has been conducted to assess the efficacy of adenosine modulation. These data, collected in more than 4,000 patients undergoing cardiac surgery, suggest that in addition to mitigation of myocardial injury, stroke also may be modulated by enhancing adenosine concentration in the area of cerebral ischemia. However, these preliminary findings must be validated in appropriately powered clinical trials. Finally, postoperative stroke and encephalopathy consume substantive resources, resulting in prolonged length-of-stay (17 days in-hospital 10 days for patients suffering Q-wavc infarction, vs 7 days for patients having no adverse outcome) and prolonged length-of-stay in the ICU following surgery (5 vs 3 vs 2 days, respectively). Hospital costs increase by approximately 3- to 4-fold in patients who suffer CNS outcomes following surgery. In conclusion, perioperative CNS morbidity and mortality is a critical problem that affects a substantial portion of the surgical population and consumes considerable health care resources. Over the next several years, attention must be focused on this important problem, and clinical and research resources should be redirected toward the solution of perioperative CNS morbidity.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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