Biomedical subjects
Publications and source records attributed to I K Crosby.
We describe a patient with an anomalous single coronary artery who presented with a syndrome of atypical chest pain. Coronary angiography revealed a single right coronary ostium, with a narrowed left coronary artery originating at the right coronary ostium. The proximal portion of the left coronary artery that was narrowed was noted to run in the aortic wall. We describe the operative management of this patient using ostial remodeling.
Between 1968 and 1981, 25 patients with acute traumatic rupture of the aorta were treated at the University of Virginia. Twenty-two of these patients (88%) had serious concomitant injuries. The aortic tear was just distal to the left subclavian artery in 19 patients (76%), and at other sites in six patients (24%). Lacerations were at multiple sites in three patients (12%), in the ascending aorta in one (4%), in the distal aortic arch in two (8%), and in the descending aorta well beyond the subclavian artery in six (24%). Two of the patients (8%) died of free rupture of the aorta before reaching the operating room. The other 23 patients (92%) had operation and 17 (68%) survived. At least ten of the 17 survivors (59%), with an average follow-up of seven years, do not have a disability as a result of the injury. In this group, 24 of the 25 traumatic aortic injuries (96%) occurred in the distal aortic arch or the descending aorta and could be repaired through a left posterolateral thoracotomy.
Median sternotomy is the most common approach for repeat cardiac surgery despite the potential complications of cardiac injury. Right anterolateral thoracotomy has been recommended as an alternative for patients undergoing mitral valve replacement, but data supporting one approach over the other do not exist. To compare these procedures, the records of 43 patients who had had a previous median sternotomy and who underwent mitral valve replacement were reviewed. No statistically significant differences between patients undergoing repeat median sternotomy (33 patients) and those undergoing right anterolateral thoracotomy (10 patients) were demonstrable when compared for age, gender, New York Heart Association Functional Class, other diseased valves, urgency of operation, indication for operation, type of valve removed, type of valve implanted, length of postoperative hospitalization, length of operation, days of ventilatory support, length of intensive care unit stay, and survival (90% for thoracotomy group; 76% for median sternotomy group; p, NS). Significant differences between the two groups, favoring right anterolateral thoracotomy, were apparent when comparisons were made for length of perfusion (means, 94.8 min, thoracotomy group; 121.4 min, sternotomy group; p = .03), incidence of reexploration (0%, thoracotomy group; 13%, sternotomy group; p = .001), and blood transfusion (means, 5.3 units, thoracotomy group; 11.4 units, sternotomy group; p = .003). Right anterolateral thoracotomy is an effective alternative to repeat median sternotomy for replacement of the mitral valve in patients who have had a previous median sternotomy.
The administration of magnesium ion (Mg++) has been reported to defibrillate the ventricles and to decrease the incidence of arrhythmias after cardiopulmonary bypass. In a prospective study of 76 randomly selected patients undergoing coronary artery bypass grafting, patients received either no Mg++, 0.25 mEq/kg of Mg++ during cardiopulmonary bypass with the aorta clamped, or 0.375 mEq/kg of Mg++ before cardiopulmonary bypass. Spontaneous resumption of a cardiac rhythm or spontaneous defibrillation during reperfusion was not significantly affected by Mg++ administration. However, the number of shocks to initial and to sustained defibrillation and the energy required for the last direct-current shock was greatest in patients who received Mg++ before bypass and in those whose plasma Mg++ was greater than 2.26 mg/dl. Thus, the administration of Mg++ may have adverse effects on the heart if intraoperative plasma Mg++ exceeds 2.26 mg/dl.
During cardiopulmonary bypass, 150 cardiac surgical patients were prospectively evaluated for the number, energy, current, and success rates of direct current (DC) shocks required to terminate reperfusion ventricular fibrillation (1 degree) or ventricular fibrillation occurring subsequent to a nonfibrillatory reperfusion rhythm (2 degrees). Thirty-one percent of 1-J shocks and 58% of 2.5-J shocks defibrillated. Above 2.5 J, the defibrillation success rate reached a plateau of 50-60%. Myocardial resistance decreased significantly after the first shock but remained stable during subsequent shocks. Lower defibrillating currents and myocardial resistances than had been previously reported were observed. The feasibility of low-energy defibrillation during cardiopulmonary bypass was therefore documented.
The effects of different techniques of aortocoronary bypass grafting on reperfusion cardiac rhythm and ventricular function have not been systematically evaluated for possible advantages or disadvantages. The placement of proximal anastomoses before cardiopulmonary bypass and sequential coronary grafting with reperfusion via both the grafts and the native circulation were prospectively compared to traditional grafting and reperfusion via native arteries. More than 40 biochemical, thermal, temporal, hemodynamic, and other variables, including arrhythmias and myocardial failure, were measured intraoperatively and postoperatively. Spontaneous resumption of a cardiac rhythm occurred more frequently with traditional grafting technique in association with a larger cardioplegia volume and a higher serum potassium. However, the disadvantage of the traditional technique was a higher incidence of cardiac failure postoperatively and greater use of isoproterenol after discontinuation of bypass. While cardiac rhythm resumed spontaneously more often with the traditional technique, the increased incidence of cardiac failure postoperatively has serious implications. Thus, placement of proximal anastomoses before cardiopulmonary bypass seems warranted.
The merit of carotid endarterectomy for patients who previously have sustained a completed stroke remains controversial. Between January 1976 and December 1983, 118 stroke patients with mild to severe permanent neurologic deficits were evaluated. Fifty-nine patients were managed nonoperatively and 59 operatively. Both cohorts were similar in age and sex distribution, incidence of hypertension (69%), diabetes mellitus (25%), and cardiac disease (39%). In the long-term follow-up (medical cohort average was 44.1 +/- 5.0 months; surgical cohort average, 41.8 +/- 3.7 months) the overall survival rate was comparable, that is, there were nine medical deaths and eight surgical deaths. However, there was a significant difference in the development of new neurologic deficits. Twelve of the 59 unoperated patients had new neurologic deficits and three patients died at 12, 36, and 48 months as a result of a recurrent stroke. New neurologic deficits developed in only two of the 59 surgical patients and there were no stroke-related deaths. When the cumulative probability of remaining free from recurrent deficits was examined in the surviving patients at 6 years, all of the patients in the operated group remained free from recurrent deficits, whereas only 58% of the patients in the unoperated group were free of new neurologic deficits (p = 0.02). These data suggest that stroke patients with fixed mild to moderate neurologic deficits and with carotid lesions may be protected from recurrent neurologic complications by carotid endarterectomy.
Mitral or tricuspid valve replacement with the Beall Model 103 or 104 prosthesis has been associated with a high incidence of late prosthetic malfunction which has necessitated reoperation. Between 1972 and 1975, 57 patients underwent single valve replacement (55 mitral and two tricuspid) with Beall Model 103 or 104 valvular prostheses and survived at least 2 years. The mean follow-up time was 73.7 months (range 24 to 119 months). Of these patients, 22 required explantation of the prosthesis; there was an operative mortality of 27%. Major prosthetic malfunction occurred in four patients: Two occluders were embolized and two occluders were fixed in the open position. All four patients required urgent operation, and two of them died. The development of symptoms of congestive heart failure, systolic murmur, or hemolysis were the reasons for cardiac catheterizations and possible reoperation. Nineteen patients had cardiac catheterization. Fifteen of these subsequently underwent reoperation, with a mortality of 26%. Three patients were considered inoperable. Cardiac catheterization data revealed significant prosthetic regurgitation in all patients: pulmonary capillary pressure 29.9 mm Hg +/- 6.7 (standard deviation); V wave 31.5 mm Hg +/- 12.0; left ventricular end-diastolic pressure 18.0 mm Hg +/- 7.8. Comparison of hemolysis indicators in this group to those of asymptomatic patients revealed that the former had a significant elevation in lactic dehydrogenase (p = 0.038) and a lowered hematocrit value (p = 0.017). Waiting for severe symptomatic deterioration to justify reoperation risks the development of left ventricular dysfunction and possible emergency reoperation with a high operative mortality.
In a prospective study of 99 patients with coronary artery disease, reperfusion of the heart after a period of ischemia (protected by contemporary techniques of myocardial preservation) resulted in spontaneous resumption of cardiac electrical activity in 53%, spontaneous defibrillation in 10%, reperfusion ventricular fibrillation (VF) in 32% and indeterminate rhythm in 5%. In hearts spontaneously developing rhythms excluding VF (as opposed to hearts requiring direct-current shock), factors significantly associated were a higher plasma potassium concentration (5.2 vs 4.8 mEq/liter), shorter reperfusion time (1 vs 4 minutes), higher plasma magnesium concentration (1.36 vs 1.25 mg/dl) and a lower myocardial temperature (27 vs 32 degrees C). The duration of ischemia, arterial blood gas levels, plasma catecholamine levels, plasma ionized calcium levels, volume of cardioplegia and mean arterial pressure did not relate to occurrence of spontaneous episodes. However, VF developed in 39 of 52 patients (75%) with spontaneous resumption of electrical activity. This event was associated with lower myocardial temperature. Thus, direct-current shocks were ultimately required in 77 of the 99 patients (78%). Although certain thermal, biochemical and hemodynamic variables facilitate spontaneous resumption of cardiac rhythm, the development of VF may negate the potential benefit of this event in the prevention of myocardial damage from direct-current defibrillation.
Eighteen (1.4%) of 1,251 patients who underwent cardiac operations during a three-year period had new sustained ventricular tachycardia (12 patients) or ventricular fibrillation (6 patients) not caused by but resulting in hemodynamic compromise. In 13 patients, the initial arrhythmia occurred in the first 48 hours postoperatively. Lidocaine was being administered to 10 of these patients for suppression of previously noted ventricular ectopy, but it did not prevent the occurrence of the arrhythmia. The initial episode was fatal for 5 patients. Two of these deaths were directly related to the adverse effects of the antiarrhythmic agents used to suppress ventricular tachycardia or fibrillation. Five of 10 survivors underwent electrophysiological studies after initial resuscitation. In all 5, programmed ventricular stimulation reproduced the clinical arrhythmia. There have been 2 late sudden deaths in patients who either did not undergo or remained uncontrolled at electrophysiological study during serial drug trials. Our experience suggests that a cardiac operation may unmask or induce potentially lethal arrhythmias that previously had not been apparent. Pharmacological suppression of ventricular ectopy does not necessarily prevent ventricular tachycardia or ventricular fibrillation in the early postoperative period. Electrophysiological study may be helpful in determining the appropriate prophylactic therapy in such patients.
Previous studies have suggested that shocks of 5-10 J are required for direct ventricular defibrillation during open heart surgery. However, the efficacy of shocks of less than 5 J, the effects of thermal, biochemical, and temporal factors, and the influence of disease process on defibrillation have not been fully investigated, particularly with modern techniques of myocardial preservation. The purpose of this prospective study in 150 adult cardiac surgical patients was to evaluate the energy, current, and myocardial resistance with low energy DC shocks of 1, 2.5, and 5 J and to relate which biochemical, temporal, thermal, or other factors influence the outcome of a DC shock. Twenty-eight percent of shocks of 1 J and 55% of shocks of 2.5 J produced defibrillation. Above 2.5 J, the success rate reached a plateau at 55%. Other factors associated with the success of DC shocks were high normal serum potassium levels, high PaO2, high ionized calcium levels, and longer reperfusion times at mean arterial and coronary perfusion pressures above 50 mm Hg. Disease process may also play a role because patients with valvular heart disease were more difficult to defibrillate. Heart weight and thickness of ventricular myocardium, measured angiographically, appeared less important in direct defibrillation, except with 1 J shocks when thinner-walled ventricles defibrillated more easily.
Information on the role of the intensivist in postoperative cardiovascular patient care was obtained from a national survey of cardiac surgeons. The cardiac surgeon today retains overall responsibility for patient care. However, when intensivists are present, they significantly reduce the involvement of the cardiac surgeon in most aspects of patient care, particular ventilatory support. Intensivists are less likely to practice in nonteaching hospitals and less likely to be present in those cardiac surgical units that are not combined with other services. Because of the preponderance of intensivists in training programs, the surgical resident's role in patient care may be reduced in the future.
Because thallium-201 uptake relates directly to the amount of viable myocardium and nutrient blood flow, the potential for exercise scintigraphy to predict response to coronary revascularization surgery was investigated in 47 consecutive patients. All patients underwent thallium-201 scintigraphy and coronary angiography at a mean (+/- standard deviation) of 4.3 +/- 3.1 weeks before and 7.5 +/- 1.6 weeks after surgery. Thallium uptake and washout were computer-quantified and each of six segments was defined as normal, showing total or partial redistribution or a persistent defect. Persistent defects were further classified according to the percent reduction in regional thallium activity; PD25-50 denoted a 25 to 50% constant reduction in relative thallium activity and PD greater than 50 denoted a greater than 50% reduction. Of 82 segments with total redistribution before surgery, 76 (93%) showed normal thallium uptake and washout postoperatively, versus only 16 (73%) of 22 with partial redistribution (probability [p] = 0.01). Preoperative ventriculography revealed that 95% of the segments with total redistribution had preserved wall motion, versus only 74% of those with partial redistribution (p = 0.01). Of 42 persistent defects thought to represent myocardial scar before surgery, 19 (45%) demonstrated normal perfusion postoperatively. Of the persistent defects that showed improved thallium perfusion postoperatively, 75% had normal or hypokinetic wall motion before surgery, versus only 14% of those without improvement (p less than 0.001). Whereas 57% of the persistent defects that showed a 25 to 50% decrease in myocardial activity demonstrated normal thallium uptake and washout postoperatively, only 21% of the persistent defects with a decrease in myocardial activity greater than 50% demonstrated improved perfusion after surgery (p = 0.02). Thus, preoperative quantitative thallium-201 scintigraphy appears useful in predicting response to revascularization surgery, and some persistent defects may revert to normal thallium uptake after surgery. Importantly, the preoperative distinction between viable and nonviable myocardium can be reasonably established by quantitating the amount of persistent reduction in thallium uptake and correlating this with preoperative wall motion.
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A prospective analysis of the angiographic and operative anatomic and reconstructive variables that influenced graft patency was undertaken at the University of Virginia Medical Center in 50 consecutive patients. Postoperative restudy showed that 18 of the 168 grafts performed were occluded due to venous disease, inadequate run-off, or sequential design error. Angiographic artery size was 27% larger than operative estimations; graft patency significantly increased with increasing distal artery diameter, with decreasing venous conduit diameter, and with good graftability rating of the vessels preoperatively. Ejection fraction, the degree of arterial stenosis, and the source of the saphenous vein conduit (the thigh or the lower leg) had no influence on graft patency. Simple grafts had a 96% patency, while sequential grafts had an 80% patency. When design error for sequential grafts was eliminated, the sequential patency rate rose to 88%. For revascularization of small circumflex vessels, consideration should be given to variation in the sequential grafting technique to improve patency in these vessels.
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Explore the source record for details and available documents.