Allen S. Hudspeth

Risk Factors and Solutions for the Development of Neurobehavioral Changes After Coronary Artery Bypass Grafting

BACKGROUND As operative mortality for coronary artery bypass grafting has decreased, greater attention has focused on neurobehavioral complications of coronary artery bypass grafting and cardiopulmonary bypass. METHODS To assess risk factors and to evaluate changes in surgical technique, between 1991 and 1994 we evaluated 395 patients undergoing coronary artery bypass grafting with an 11-part neurobehavioral battery administered preoperatively and at 1 and 6 weeks postoperatively. Patients were instrumented with 5-MHz focused continuous-wave carotid Doppler transducers intraoperatively to estimate cerebral microembolism as an instantaneous perturbation of the velocity signal. Microembolism data were quantitated and compared with surgical technical maneuvers during operation and with neurobehavioral deficit (> or = 20% decline from preoperative performance on two or more neurobehavioral tests) postoperatively. These data and patient demographics were statistically analyzed (chi2, t test) and the results at 2 years (1991 and 1992; group A) were used to influence surgical technique in 1993 and 1994 (group B). RESULTS Significantly associated with new neurobehavioral deficits were increasing patient age (p < 0.05), more than 100 emboli per case (p < 0.04), and palpable aortic plaque (p < 0.02). Group B patients had a significant decline in the neurobehavioral event rate (group A, 69%, 140/203; versus group B, 60%, 115/192; p < 0.05) of postoperative neurobehavioral deficits at 1 week and at 1 month (group A, 29%, 52/180; versus group B, 18%, 35/198; p < 0.01). The stroke rate was less than 2% in both groups (p = not significant). Modifications of surgical technique used in group B patients included increased use of single cross-clamp technique, increased venting of the left ventricle, and application of transesophageal and epiaortic ultrasound scanning to locate and avoid trauma to aortic atherosclerotic plaques. CONCLUSIONS Neurobehavioral changes after coronary artery bypass grafting are common and associated with cerebral microembolization. Surgical technical maneuvers designed to reduce emboli production may improve neurobehavioral outcome.

A Prospective Study of Sternal Wound Complications

Eight hundred seventy patients were enrolled in a prospective study to identify risk factors for sternal wound complications following open-heart operations. The 0.8% incidence of major sternal complications was similar to that reported in the literature by other centers. The effects of age, sex, weight, operative time, type of procedure, resident versus attending surgeon, prolonged ventilatory support, reoperation for bleeding, external cardiac massage, and Dacron versus wire suture for sternal closure were assessed by stepwise logistic regression. Prolonged ventilation and female sex both strongly increased the risk of major sternal complications. Age and weight exerted lesser, but statistically significant, effects on the incidence of such complications. None of the other factors was associated with an increased risk of major sternal complications.

Predictive Value of Blood Clotting Tests in Cardiac Surgical Patients

Abstract This study ptospectively evaluated numerous tests of clolting function in 897 consecutive adult cardiac surgical patients over 18 months. This included coronary operation, valve replacement, and reoperative patients. The tests included activated clotting time, activated partial thromboplastin time, prothrombin time, thiombin time, fibrinogen, fibrin/fibrinogen degradation products, platelet count, and Dukes earlobe bleeding time. Other variables such as age, sex, and cardiopulmonary bypass duration were included in the multivariate analysis. Statistically significant correlations were found between 16-hour mediastinal drainage and activated partial thromboplastin time, fibrinogen, activated clotting time, fibrin/fibrinogen degradation products, platelet count, and prothrombin time. Scatter plots indicate that these relationships, although statistically significant, had little predictive value and were largely significant is a result of the large number of patients in each group, which permitted weak correlations to reach statistical significance. The best multivariate model constructed could explain only 12% of the observed variation in postoperative blood loss. Because the predictive values of the tests are so low, it does not appear sensible to screen patients routinely using these clotting tests shortly after cardiopulmonary bypass.

Radial Artery-to-Aorta Pressure Difference after Discontinuation of Cardiopulmonary Bypass

To test whether the radial artery-to-aorta pressure gradient seen in some patients after cardiopulmonary bypass (CPB) is due to reduction in hand vascular resistance, the authors compared pressures in the ascending aorta with pressures in the radial artery before and after CPB in 12 patients. They increased hand vascular resistance by briefly occluding the radial and ulnar arteries at the wrist and recorded that effect on the radial artery-to-aorta pressure relationship. They also recorded the effect of wrist compression on radial artery pressures before and after CPB in 38 patients not having aortic pressure measurements. Before CPB in the first 12 patients, the radial systolic arterial pressure (SAP) was significantly higher (P less than 0.05) than the ascending aortic SAP, and wrist compression did not significantly affect that difference (P greater than 0.05). After CPB, the radial artery and aortic SAPs were not statistically different (P greater than 0.05), but wrist compression restored the higher radial artery SAP. The mean arterial pressure (MAP) was equal in four patients and 1-3 mmHg higher or lower in eight patients before CPB, and wrist compression did not alter those relationships. After CPB, MAP was equal in four patients; radial MAP was 1-3 mmHg higher or lower in six patients, and 7 and 10 mmHg lower in the last two patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Transatrial Approach to Total Correction of Tetralogy of Fallot

A transatrial approach to total correction of the tetralogy of Fallot is presented which utilizes: (1) anteroposterior incision of the right atrium near the right atrioventricular groove; (2) circumferential detachment of the septal leaflet of the tricuspid valve near the annulus; (3) pulmonary arteriotomy with valvuloplasty, if necessary; (4) retrograde displacement and resection of the stenosed infundibulum through the right atrium; (5) closure of the ventricular septal defect; (6) closure of the incision in the tricuspid valve; and (7) closure of the atriotomy.Clinical application to 10 consecutive patients, varying from acyanotia to severely cyanotic, has confirmed the advantages and simplicity of this method. Coronary arterial division, ventriculotomy, and external enlargement of the pulmonary outflow tract have been unnecessary. Relief of pulmonary stenosis has been adequate in each instance. The ventricular septal defect has been well exposed in each patient, and its closure has presented no special problem.There have been no complications associated with the method, and postoperative cardiac function has been good. Operative as well as clinical features of the method are still under investigation; however, experience thus far has led to its establishment as a routine for total correction of the tetralogy of Fallot in this clinic.

Hemodynamic Effects of Intraaortic Administration of Protamine

Seventy-nine consecutive patients were given protamine rapidly into the ascending aorta during neutralization of heparin at the end of cardiopulmonary bypass. Simultaneously left atrial, diastolic pulmonary arterial, or right atrial pressures were maintained constant by appropriate infusion of oxygenated blood into the aorta. The systemic and pulmonary vascular resistances did not change, mean arterial blood pressure increased slightly, and cardiac output increased significantly (p less than 0.001). It seems that this method of heparin neutralization is safe provided that the intravascular volume can be maintained constant.

Thoracic complications of dental surgical procedures: Hazards of the dental drill

CASE REPORTS Dental surgical procedures occasionally result in intrathoracic complications that may subsequently be encountered by clinicians. We report four patients with such complications, including pneumomediastinum, fatal descending necrotizing mediastinitis, and Lemierres syndrome. In each of these patients, the commonly used dental handpiece with exhausted air directed to the working drill point was an important, but unrecognized, predisposition to their intrathoracic complication. CONCLUSION Clinicians should be aware of the spectrum of these problems and, in particular, of the potential hazards of pressurized nonsterile air blown into open surgical sites by the dental drill.

Case report. Aortic pseudoaneurysm with aortobronchial fistula: diagnosis with CT angiography.

We report the case of an 82-year-old man with a 12-month history of recurrent hemoptysis caused by an aortobronchial fistula. Twenty-five years earlier, the patient underwent placement of an aortic graft for aortic transection sustained in a motor vehicle accident. Chest radiography and bronchoscopy showed nonspecific abnormalities. We emphasize the role of CT angiography with 2D and 3D reconstructions for the diagnosis of and surgical planning for this rare but potentially lethal aortic postoperative complication.

Cerebral Blood Flow Declines Independently of Metabolism During Hypothermic Cardiopulmonary Bypass

Although neurologic sequelae are common [1, 2] following nonpulsatile hypothermic cardiopulmonary bypass (CPB), the etiology of neurologic dysfunctions in this setting are still unclear because of the difficulty of monitoring cerebral blood flow (CBF) and cerebral metabolism during the operative procedure. We have used the Xe-133 desaturation method to measure CBF in over 200 patients during CPB to define the cerebrovascular response to a variety of physiological conditions, such as changes in pump flow [3], acid-base management [4, 5], hypercarbia [6], anesthetics [7], and to evaluate the effects of age and cerebrovascular disease [8, 9, 10]. Our studies have demonstrated a spontaneous decline in regional CBF (rCBF) during hypothermic CPB that is independent of the cerebral metabolic rate.

Coronary Revascularization in Patients with Bilateral Internal Carotid Occlusions

Coronary revascularization that is neurologically uneventful in patients with bilateral totally occluded internal carotid arteries has not been previously reported. We performed saphenous vein coronary artery bypass grafting on three such patients and observed them for 6 to 23 months. Preoperatively two of our patients had chronic stable symptoms of cerebrovascular insufficiency, and one had received cerebral revascularization via a superficial temporal-to-middle cerebral artery bypass. Controversy exists regarding proper cerebral protective maneuvers during coronary revascularization for patients with advanced cerebrovascular disease. Cerebral protection for our patients during cardiopulmonary bypass included hypothermia and high perfusion flows and pressures. Two patients also received prophylactic sodium thiopental. None of these three patients had a stroke perioperatively or during the follow-up period. We believe that these case histories strongly suggest that the functional state of the cerebral collateral circulation, as judged by preoperative neurological symptoms, predicts neurological outcome after coronary revascularization better than the specific occlusive anatomy of the extracranial carotid arteries.