R. Scott Stuart

Predictors of stroke risk in coronary artery bypass patients

BACKGROUND Stroke occurs after coronary artery bypass grafting with an incidence ranging between 0.8% and 5.2%. To identify factors associated with stroke, we prospectively examined a study cohort and tested findings in an independent validation sample. METHODS The study cohort comprised 456 patients undergoing coronary artery bypass grafting only, and the validation sample comprised 1,298 patients. Stroke was detected postoperatively by the study team and confirmed by neurologic consultation and computed tomographic scanning. RESULTS Five factors taken together were correlated with stroke: previous stroke, presence of carotid bruit, history of hypertension, increasing age, and history of diabetes mellitus. The only significant intraoperative factor was cardiopulmonary bypass time. Probabilities were calculated, and patients were placed into low, medium, and high stroke-risk groups. In the validation sample, this model was able to rank the majority of patients with stroke into the high-risk group. CONCLUSIONS These five factors taken together can identify the risk of stroke in patients having coronary artery bypass grafting. Recognition of the high-risk group will aid studies on the mechanism and prevention of stroke by modification of surgical procedures or pharmacologic intervention.

Cognitive Outcome After Coronary Artery Bypass: A One-Year Prospective Study

BACKGROUND Cognitive deficits have been reported in patients after coronary artery bypass grafting, but the incidence of these deficits varies widely. We studied prospectively the incidence of cognitive change and whether the changes persisted over time. METHODS Cognitive testing was done preoperatively and 1 month and 1 year postoperatively in 127 patients undergoing coronary artery bypass grafting. Tests were grouped into eight cognitive domains. A change of 0.5 standard deviation or more at 1 month and 1 year from patients preoperative Z score was the outcome measure. RESULTS We identified four main outcomes for each cognitive domain: no decline; decline and improvement; persistent decline; and late decline. Only 12% of patients showed no decline across all domains tested; 82% to 90% of patients had no decline in visual memory, psychomotor speed, motor speed, and executive function; 21% and 26% had decline and improvement in verbal memory and language; approximately 10% had persistent decline in the domains of verbal memory, visual memory, attention, and visuoconstruction; and 24% had late decline (between 1 month and 1 year) in visuoconstruction. CONCLUSIONS This study establishes that the incidence of cognitive decline varies according to the cognitive domain studied and that some patients have persistent and late cognitive changes in specific domains after coronary artery bypass grafting.

Valve replacement in patients with endocarditis and acute neurologic deficit

BACKGROUND Acute neurologic deficits occur in up to 40% of patients with left heart endocarditis. Appropriate evaluation and management of patients with acute neurologic dysfunction who require valve operations for endocarditis remain controversial. This retrospective review was undertaken to develop recommendations for the evaluation and treatment of these challenging patients. METHODS From 1983 to 1995, 247 patients underwent operations for left heart native valve endocarditis at the Johns Hopkins Hospital. From a review of medical and pathology records, 34 patients (14%) with preoperative neurologic deficits were identified. Data on these 34 patients were recorded and analyzed. RESULTS Causes of neurologic dysfunction included embolic cerebrovascular accident (n = 23, 68%), embolic cerebrovascular accident with hemorrhage (n = 4, 12%), ruptured mycotic aneurysm (n = 3, 9%), transient ischemic attack (n = 2, 6%), and meningitis (n = 2, 6%). Preoperative diagnostic studies included computed tomography (32 patients), magnetic resonance imaging (11 patients), cerebral angiogram (14 patients), and lumbar puncture (2 patients). Computed tomography demonstrated structural lesions in 29 of 32 patients; in only 1 patient did magnetic resonance imaging reveal a lesion not already seen on computed tomography. Of 14 patients having cerebral angiograms, 7 had a mycotic aneurysm. Three mycotic aneurysms had ruptured, and these were clipped before cardiac operations. The mean interval from onset of neurologic deficit to cardiac operation was 22.2 +/- 2.8 days for all patients and 22.1 +/- 3.0 days for those with embolic cerebrovascular accident. The hospital mortality rate was 6%. New or worse neurologic deficits occurred in 2 patients (6%). CONCLUSIONS Neurologic deficits are common in patients with endocarditis referred for cardiac operations. Despite substantial preoperative morbidity, most of these patients do well if the operation can be delayed for 2 to 3 weeks. Computed tomography scan is the preoperative imaging technique of choice, as routine magnetic resonance imaging and cerebral angiogram are unrewarding. Cerebral angiogram is indicated only if computed tomography reveals hemorrhage.

Neutrophil adhesion molecule expression during cardiopulmonary bypass with bubble and membrane oxygenators

The neutrophil-mediated tissue injury associated with cardiopulmonary bypass (CPB) is thought to require the interaction of specific neutrophil and endothelial adhesion molecules. In this study, the effects of CPB on the expression of neutrophil CD11b and CD18 (the components of the Mac-1 adhesion molecule) were examined; the effects of membrane versus bubble oxygenators on the expression of neutrophil CD11b and CD18 were compared; and the plasma levels of the intercellular adhesion molecule-1 (cICAM-1), an inducible endothelial adhesion molecule, were measured. In addition, the time courses of complement activation and neutrophil granule release were measured to determine their temporal relationship to the expression of the neutrophil adhesion molecule. Fifteen adult patients underwent procedures requiring cardiopulmonary bypass; hollow-fiber membrane oxygenators were used in 8 (group M) and bubble oxygenators were used in 7 (group B). Blood samples were drawn before, during, and after CPB for determination of the expression of neutrophil CD11b and CD18 (immunofluorescent flow cytometry), and the plasma cICAM-1, elastase, lactoferrin (enzyme-linked immunoabsorbent assay), and plasma C3a (radioimmunoassay) levels. CPB caused an immediate and sustained increase in the neutrophil CD11b and CD18 expression in both groups; after 60 minutes of CPB, CD11b expression had increased by 116.9% +/- 19.1% in group B and by 79.3% +/- 8.5% in group M (p = 0.78). Over the same period, CD18 expression increased by 97.2% +/- 17.9% in group B and by 72.4% +/- 16.8% in group M (p = 0.67).(ABSTRACT TRUNCATED AT 250 WORDS)

Heparin-coated bypass circuits reduce pulmonary injury☆☆☆

Heparin coating of the extracorporeal circuit not only reduces heparin requirements during cardiac operations but also may reduce organ injury associated with cardiopulmonary bypass (CPB). To examine this possibility, pulmonary injury and neutrophil adhesion molecule expression after CPB were studied in pigs undergoing CPB with a standard extracorporeal circuit (group S, n = 6) or a heparin-coated CPB circuit (Carmeda BioActive Surface) (group HC, n = 6). Pigs received heparin sodium (300 U/kg intravenously) and then underwent 90 minutes of hypothermic (28 degrees C) CPB using membrane oxygenators, followed by 2 hours of observation. Blood samples were obtained for determination of neutrophil number and expression of the neutrophil adhesion molecule subunit CD18 (by immunofluorescence flow cytometry). The CPB-associated injury was less in group HC. Two hours after CPB, the arterial oxygen tension group was higher in group HC (597.2 +/- 31.2 versus 220.5 +/- 42.3 mm Hg; p < 0.0001), the pulmonary vascular resistance was lower in these animals (408.6 +/- 69.4 versus 1,159.8 +/- 202.4 dyne.s.cm-5; p = 0.02), and the static compliance was higher in group HC (66.4 +/- 5.4 versus 39.8 +/- 5.8 mL/mm Hg; p = 0.004). After 60 minutes of CPB, both groups had similar increases in expression of the neutrophil adhesion molecule subunit CD18 (29.4% +/- 19.5% versus 26.0% +/- 24.4%, group S and group HC, respectively) and similar decreases in neutrophil counts (6,056 +/- 1,285 to 2,453 +/- 979 cells/microL versus 6,010 +/- 1,748 to 3,197 +/- 1,225 cells/microL, group S and group HC, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Neurologic injury in cardiac surgical patients with a history of stroke.

BACKGROUND Controversy still exists as to whether patients with previous stroke are at increased risk for neurologic complications after heart operations. METHODS We performed a prospective analysis of 1,000 consecutive patients undergoing cardiac operations requiring cardiopulmonary bypass, without hypothermic circulatory arrest. Of the 1,000 patients, 71 had previously documented stroke (study group); 2 control patients with no history of stroke were selected for each of these patients (control group, n = 142). There were no significant differences between the study and control patients with respect to established risk factors for neurologic complications. RESULTS Compared with controls, study patients took longer to awaken (12.6 +/- 10.9 versus 3.5 +/- 2.1 hours; p < 0.0001) and longer to extubate (29.5 +/- 29.3 versus 9.1 +/- 5.2 hours; p < 0.001), and had a greater incidence of reintubation (7 of 71, 9.9% versus 2 of 142, 1.4%; p < 0.01) and postoperative confusion (26 of 71, 36.6% versus 7 of 142, 4.9%; p < 0.001). There was a higher incidence of focal neurologic deficit among study patients (31 of 71, 43.7% versus 2 of 142, 1.4%; p < 0.001). These deficits included new stroke (6 of 71, 8.5%) as well as the reappearance of previous deficits (19 of 71, 26.8%) or worsening of previous deficits (6 of 71, 8.5%), without new abnormalities on head computed tomography or magnetic resonance imaging. Study patients with neurologic deficit had longer cardiopulmonary bypass times than did study patients without deficit (146 +/- 48.5 versus 110 +/- 43.3 minutes; p < 0.001). The 30-day mortality rate was greater in study patients than in controls (5 of 71, 7% versus 1 of 142, 0.7%; p < 0.02), with four deaths among the 6 study patients with a new stroke (66.7%). CONCLUSION This analysis identifies a group of patients at high risk for neurologic sequelae and confirms the vulnerability of the previously injured brain to cardiopulmonary bypass, as evidenced by reappearance or exacerbation of focal deficits in such patients.

Aortic valve replacement in the elderly. Risk factors and long-term results.

OBJECTIVE The current study was undertaken to determine long-term results of aortic valve replacement (AVR) in the elderly, to ascertain predictors of poor outcome, and to assess quality of life. SUMMARY BACKGROUND DATA Aortic valve replacement is the procedure of choice for elderly patients with aortic valve disease. The number of patients aged 70 and older requiring AVR continues to increase. However, controversy exists as to whether surgery devoted to this subset reflect a cost-effective approach to attaining a meaningful quality of life. METHODS This study reviews data on 247 patients aged 70 to 89 years who underwent isolated AVR between 1980 and 1995; there were 126 men (51%) and 121 women (49%). Follow-up was 97% complete (239/247 patients) for a total of 974.9 patient-years. Mean age was 76.2 +/- 4.8 years. Operative mortality and actuarial survival were determined. Patient age, gender, symptoms, associated diseases, prior conditions, New York Health Association class congestive heart failure, native valve disease, prosthetic valve type, preoperative catheterization data, and early postoperative conditions were analyzed as possible predictors of outcome. Functional recovery was evaluated using the SF-36 quality assessment tool. RESULTS Operative mortality was 6.1% (15/247). Multivariate logistic regression showed that poor left ventricular function and preoperative pacemaker insertion were independent predictors of early mortality. After surgery, infection was predictive of early mortality. Overall actuarial survival at 1, 5, and 10 years was 89.5 +/- 2% (198 patients at risk), 69.3 +/- 3.4% (89 patients at risk), and 41.2 +/- 6% (13 patients at risk), respectively. Cox proportional hazards model showed that chronic obstructive pulmonary disease and urgency of operation were independent predictors of poor long-term survival. Postoperative renal failure also was predictive of poor outcome. Using the SF-36 quality assessment tool, elderly patients who underwent AVR scored comparably to their age-matched population norms in seven of eight dimensions of overall health. The exception is mental health. CONCLUSIONS Aortic valve replacement in the elderly can be performed with acceptable mortality. Significant preoperative risk factors for early mortality include poor left ventricular function and preoperative pacemaker insertion. Predictors of late mortality include chronic obstructive pulmonary disease and urgency of operation. These results stress the importance of operating on the elderly with aortic valve disease; both long-term survival and functional recovery are excellent.

Valvular disease in the elderly: Influence on surgical results

Aortic valve disease in the elderly is primarily calcific stenosis with preservation of left ventricular function. In contrast, mitral valve disease in the elderly often is ischemic in nature with damage occurring to both valve and myocardium. The present study was undertaken to compare results of aortic (AVR) and mitral valve replacement (MVR) in the elderly and to ascertain predictors of poor outcome. Because patients who had concomitant coronary artery bypass grafting (CABG) are included (51% for AVR, 55% for MVR), patients who had isolated CABG were used as a comparison group. Between January 1, 1984, and June 30, 1991, 1,386 patients aged 70 years and older underwent CABG (n = 1,043), AVR (n = 245), or MVR (n = 98). The operative mortality rates were 5.3% for AVR, 20.4% for MVR, and 5.8% for CABG. Late follow-up of patients undergoing operation in 1984 and 1985 was available for 98% (231/237). Overall survival was comparable for all three groups through the first 5 years of follow-up (AVR, 68% +/- 8%; MVR, 73% +/- 8%; CABG, 78% +/- 3%). After 5 years, survival for patients having AVR and MVR was less than that for those having CABG. Patient age, sex, New York Heart Association functional class, concomitant CABG, prosthetic valve type, native valve pathology, and preoperative catheterization data were examined as possible predictors of outcome by multivariate logistic regression.(ABSTRACT TRUNCATED AT 250 WORDS)

Neutrophil Modulation Results in Improved Pulmonary Function After 12 and 24 Hours of Preservation

Neutrophils are important mediators of reperfusion injury, and suppression of neutrophil function or numbers can reduce reperfusion injury and improve long-term organ preservation in transplantation. NPC 15669, a leumedin, is a novel compound that prevents recruitment of neutrophils at inflammatory foci by inhibiting CD11b/CD18 adhesion molecule expression. NPC 15669 was used to inhibit neutrophil adhesion during reperfusion of isolated rabbit lungs after 12 and 24 hours of cold storage. Lungs (New Zealand White male rabbits, 2 to 3 kg) were flushed with 4 degrees C Euro-Collins (EC) solution, harvested en bloc, stored under various study conditions, and reperfused for 3 hours with fresh whole blood at 37 degrees C in an isolated perfusion system at constant flow and an inspired oxygen fraction of 1. Four groups (n = 6 each) were studied. Group I underwent immediate whole blood reperfusion. Group II were stored for 12 hours in 4 degrees C EC solution before reperfusion. Group III were stored for 12 hours in 4 degrees C EC solution and reperfused with whole blood containing NPC 15669 (10 mg/kg whole body weight). Group IV were stored for 24 hours in 4 degrees C EC solution and reperfused with whole blood containing NPC 15669 (10 mg/kg). Pulmonary artery and peak airway pressures were significantly lower and compliance higher in groups III and IV lungs after 3 hours of reperfusion (p < 0.05) compared with group I. Group I and III lungs had significantly less edema than group II (p < 0.05). The arterial partial pressure of oxygen was similar in all stored groups (II to IV).(ABSTRACT TRUNCATED AT 250 WORDS)

Management of the Atherosclerotic Ascending Aorta With Endoaortic Occlusion

Application of an external cross-clamp to an atherosclerotic ascending aorta increases the risk of an embolic event and traumatic injury of the aorta. Currently, there are limited management options in these patients when the clinical situation requires cardiac arrest during an operation. We present our approach to these patients using the Heartport Endoaortic Clamp (Heartport, Redwood City, CA).