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Biomedical subjects

J A Burkholder

Publications and source records attributed to J A Burkholder.

At least 19 recordsLinked to original sources
PubMed1996

A model that predicts morbidity and mortality after coronary artery bypass graft surgery.

OBJECTIVES: This study was performed to develop a method for identifying patients at increased risk for morbidity or mortality after coronary artery bypass graft surgery. BACKGROUND: Postoperative morbidity is more common than mortality and is important because of its relation to cost. METHODS: Univariate and forward stepwise logistic regression analysis was used to retrospectively analyze a group of 1,567 consecutive patients who underwent bypass surgery between July 1991 and December 1992. We developed a model that predicted postoperative morbidity or mortality, or both, which was then prospectively validated in a group of 1,235 consecutive patients operated on between January 1993 and April 1994. A clinical risk score was derived from the model to simplify utilization of the data. RESULTS: The following factors, listed in decreasing order of significance, were found to be significant independent predictors: cardiogenic shock, emergency operation, catheterization-induced coronary artery closure, severe left ventricular dysfunction, increasing age, cardiomegaly, peripheral vascular disease, chronic renal insufficiency, diabetes mellitus, low body mass index, female gender, reoperation, anemia, cerebrovascular disease, chronic obstructive pulmonary disease, renal dysfunction, low albumin, elevated blood urea nitrogen, congestive heart failure and atrial arrhythmias. Observed morbidity and mortality for the validation group fell within the 95% confidence interval of that predicted by the model. Costs were closely related to the incidence of postoperative morbidity. CONCLUSIONS: Analysis of preoperative patient variables can predict patients at increased risk for morbidity or mortality, or both, after bypass surgery. Increased morbidity results in higher costs. Different strategies for high and low risk patients should be used in cost reduction efforts.

Aged↗
PubMed1996

A model for predicting transfusion after coronary artery bypass grafting.

BACKGROUND: Blood conservation has become an important issue in cardiac surgery. This study was undertaken to determine if the need of blood transfusion could be predicted from preoperative patient variables. METHODS: From January 1, 1992, to December 31, 1993, 2,033 patients having isolated coronary artery bypass grafting procedures were studied; 1,446 (71%) were male and 587 (29%), female. The mean age was 65.1 +/- 9.9 years (range, 31 to 88 years). Emergency operation, urgent operation, and reoperations were done in 78 (4%), 188 (9%), and 189 (9%) patients, respectively. In the entire group, 1,245 (61%) received transfusion during hospitalization, and 788 (39%) did not. Logistic regression analysis was used to construct a model that predicted the need of transfusion of packed red blood cells after coronary artery bypass grafting. A transfusion risk score was constructed by assigning points to independent predictive factors on the basis of the logistic regression coefficient and the odds ratio. Preoperative predictors of transfusion were emergency operation, urgent operation, cardiogenic shock, catheterization-induced coronary occlusion, low body mass index, left ventricular ejection fraction lower than 0.30, age greater than 74 years, female sex, low red cell mass, peripheral vascular disease, insulin-dependent diabetes, creatinine level greater than 1.8 mg/dL, albumin value lower than 4 g/dL, and redo operation. RESULTS: The mean transfusion risk score for patients receiving 0, 1 to 4, and greater than 4 units of packed red blood cells was 2.3 +/- 0.9, 5.2 +/- 3.0, and 9.6 +/- 3.5, respectively (p = 0.001). Patients with a score higher than 6 had a 95% transfusion incidence. The predictive model was validated on 422 patients having coronary artery bypass grafting from January 1 to May 31, 1994. The observed rates of the validation group fell within the 95% confidence intervals of the predicted rates. CONCLUSIONS: These data demonstrate that readily available patient variables can predict patients at risk for transfusion. Routine use of aprotinin and other adjustments of cardiopulmonary bypass should be considered to reduce transfusion in high-risk patients.

Adult↗
PubMed1991

Long-term efficacy of an antitachycardia pacemaker and implantable defibrillator combination.

Antitachycardia pacemakers and implantable cardioverter defibrillators (ICD) were implanted in 14 patients to control recurrent hemodynamically stable ventricular tachycardia (VT). All patients underwent extensive preimplant testing in the electrophysiology laboratory documenting that in each patient at least 50 episodes of VT could be reliably terminated by an external model of the antitachycardia pacemaker. The burst scanning mode of antitachycardia pacing was used in all patients. ICDs were implanted solely as a back up should acceleration of VT occur, and all had high nonprogrammable rate cutoffs (mean 191 +/- 12 beats/min). During a mean follow-up of 25 +/- 6 months, 6,029 episodes of VT were treated in the 14 patients. Only 103 ICD discharges were required (approximately one discharge per 60 episodes of VT). Ten of the 14 patients received discharges from their ICDs. No deaths have occurred. All devices remain active and in the automatic mode. Thus, an antitachycardia pacemaker and ICD combination can safely and effectively terminate VT in highly selected patients who are subjected to extensive preimplant testing. In such patients, the vast majority of episodes of VT can be terminated with antitachycardia pacing, and only rarely is a discharge required from the ICD.

Aged↗
PubMed1990

Recent experience with major sternal wound complications.

During a recent 1-year period, 31 patients sustained a major sternal wound infection and sternal dehiscence developed in 6 patients. Multiple potential risk factors were tabulated in these patients and in a control group selected from 1,521 patients undergoing sternotomy during the same time period. The overall infection rate was 2.1%, and the mortality rate in the patients with sternal infection or dehiscence was 16.2%. Chronic obstructive pulmonary disease, prolonged intensive care unit stay, respiratory failure, connective tissue disease, and male sex were significantly higher in the group with sternal infection or dehiscence (p less than 0.05). Advanced age and low cardiac output episodes were more frequent in this group, but only approached statistical significance. Although several risk factors may have been interrelated, male sex and the presence of pulmonary disease were statistically independent predictors of sternal wound infection. Risk factors may be helpful in identifying high-risk patients for additional prophylactic measures.

Aged↗
PubMed1990

Efficacy of the automatic implantable cardioverter-defibrillator in prolonging survival in patients with severe underlying cardiac disease.

The ability of the automatic implantable cardioverter-defibrillator to prolong overall survival, particularly in patients with significantly depressed cardiac function, has not been well documented. Of 119 patients who received the implantable defibrillator in this institution, 40 had a left ventricular ejection fraction less than 30% (Group A) and 79 had an ejection fraction greater than or equal to 30% (Group B). For each group, cumulative survival was compared with the projected survival if the implantable defibrillator had not been used. Projected survival was based on the assumption that the first appropriate shock would have resulted in death without the defibrillator. For Group A, the 3 year cumulative survival rate was 67 +/- 12% versus a projected survival rate of 6 +/- 15% (p less than 0.001). For Group B, the 3 year cumulative survival rate was 96 +/- 3% versus a projected survival rate of 46 +/- 8% (p less than 0.001). Both the cumulative and projected survival rates for patients in Group A were significantly worse than for patients in Group B (p less than 0.01). The projected survival rates for both Groups A and B were comparable with the observed survival rate in similar patients treated without the implantable defibrillator. In summary, the implantable cardioverter-defibrillator significantly prolonged overall survival, even in patients with poor cardiac function. The technique of estimating projected survival appears to allow a realistic estimate of the reduction in mortality achieved by the defibrillator.

Adult↗
PubMed1989

Twenty-five-year review of the Magovern-Cromie sutureless aortic valve.

We reviewed 25 years (4,798 patient-years) of aortic valve replacement with the Magovern-Cromie sutureless valve. Operative mortality was 11% for isolated aortic valve replacement and 15% for aortic valve replacement with concomitant cardiac procedures. Since 1981, operative mortality has declined to 4.9%. Valve-related morbidity was in the lower expected ranges for prosthetic aortic valves: ball variance, 0.3%/patient-year; paraprosthetic leak, 0.41%/patient-year; valve endocarditis, 0.43%/patient-year; valve thrombosis, 0.04%/patient-year; and embolic events, 3.95%/patient-year. The incidence of aortic valve reoperation was 0.76%/patient-year. The 5-year, 10-year, and 20-year probability of survival corrected for normal mortality was 77%, 64%, and 52% for all discharged patients. This review confirms the Magovern-Cromie valve to be a safe, durable, and efficient prosthetic valve.

Adolescent↗
PubMed1989

Traumatic aortic transection: repair using left atrial to femoral bypass.

Traumatic aortic transection is a life-threatening surgical emergency. Therapy must be directed at rapid repair and prevention of postoperative complications, the most serious being paraplegia. Controversy over the optimal method of repair exists-specifically whether the use of a shunt modifies the outcome. Our series of 17 patients using left atrial to femoral bypass with the Biomedicus pump will be discussed. Preoperative preparation and operative technique will be outlined. Mortality in this series was 18%, the incidence of paraplegia was 0.

Adult↗
PubMed1988

Paced skeletal muscle for dynamic cardiomyoplasty.

Four patients, each with a history of myocardial infarction and diffuse coronary artery disease, underwent application of left latissimus dorsi (LD) muscle with intact neurovascular bundle to the anterolateral wall of the left ventricle. The muscle was conditioned over a six-week period subsequent to operation in 3 patients and was conditioned preoperatively with a burst stimulus in the fourth. Biopsy specimens confirm the experimental data that human skeletal muscle can be electrically conditioned over a six- to ten-week period to contain mainly fatigue-resistant type I fibers. All patients survived the procedure, and 3 showed improvement secondary to aneurysmectomy. In Patient 1, a modified resection was performed, and at 28 months after operation, at the 75-W level of exercise, the ejection fraction was 54% paced versus 45% nonpaced. In Patient 2, at 12 months, the ejection fraction at rest was 44% paced versus 30% nonpaced. Doppler echo studies confirmed the presence of the flap and its function in the paced and nonpaced mode. The third patient died of a sudden ventricular arrhythmia 2 months following operation. An infected, nonfunctioning, degenerated flap was found at autopsy. Patient 4 did not have an aneurysm. She received a bypass graft to the right coronary artery and underwent cardiomyopexy in an attempt to relieve medically refractory incapacitating chronic congestive heart failure. Ten months postoperatively, ejection fraction at rest was 33% paced versus 25% nonpaced. Constrictive myopathy has not been encountered in any of these patients.

Biopsy↗
PubMed1987

Recovery of the failing canine heart with biventricular support in a previously fatal experimental model.

Prolonged normothermic ischemia in the canine model is generally fatal with standard resuscitative techniques. To determine whether such myocardial injury is recoverable with biventricular support, we subjected 10 dogs to 45 minutes of ischemia at 37 degrees C. After ischemia, the animals were supported for 24 hours with biventricular assist with the centrifugal pump. During early reperfusion, none of the hearts could sustain a stable rhythm or blood pressure. Myocardial adenosine triphosphate concentration, expressed as micromoles per gram of heart protein, was dramatically reduced from a control of 31.5 +/- 2.4 to 14.6 +/- 2.9 (p less than 0.01 versus control), a 54% reduction. Ultrastructural analysis did not reveal the explosive cell swelling of irreversible cell injury. After 12 hours of biventricular assist, developed pressure partially recovered to 60.0 +/- 10 mm Hg (p less than 0.01 versus control) and maximal positive dP/dt measured 2,649 +/- 412 mm Hg/sec (p less than 0.01 versus control). Adenosine triphosphate concentration increased to 25.2 +/- 5.5 (p less than 0.01 versus control). Electron microscopic examination showed less chromatin clumping, no further mitochondrial distortion, and more abundant glycogen. After 24 hours of biventricular assist, cardiac output in the seven dogs successfully weaned from biventricular assist measured 3.6 +/- 0.6 L/min, developed pressure recovered to 76.3 +/- 8.9 mm Hg, and its first derivative recovered to 4,282 +/- 585 mm Hg/sec (all measurements not significant compared with control). Examination by an electron microscope revealed no severe mitochondrial injury.

Adenosine Triphosphate↗
PubMed1986

Mechanical support of the failing heart.

Mechanical ventricular assist with a centrifugal pump with or without anticoagulation for an extended period has been used in 41 patients with postcardiotomy ventricular failure. Left ventricular, right ventricular, and biventricular assist were required. The efficacy and safety of mechanical ventricular assist have been documented. Marked improvement in survival has been observed in the more recent part of this series, and is attributed to earlier employment of the assist device, maintenance of better flow rates near physiological levels, and use of biventricular assist to provide effective circulatory support. Mechanical ventricular assist is easy to use, and the conversion from ordinary cardiopulmonary bypass is also easy. Therefore, mechanical assist provides a very effective means of temporary circulatory assist.

Adult↗
PubMed1986

Is percutaneous insertion of the intra-aortic balloon pump through the femoral artery the safest technique?

Between Jan. 1, 1979, and Sept. 30, 1983, 423 intra-aortic balloon pumps (IABPs) were successfully inserted into 400 patients; IABPs could not be inserted in 36 patients (success rate 91.7%). Before 1980 all balloons were inserted surgically through a graft and by 1983 virtually all IABPs were inserted by percutaneous techniques. Infectious complications occurred in 12.3% of IABPs inserted by the open technique and 1.5% of IABPs inserted percutaneously (p less than 0.001). Major ischemic complications were not significantly different between the two groups when all of the patients were analyzed together (p greater than 0.5) and when only the surviving patients were analyzed (p greater than 0.75). However, ischemic complications occurred in 32.9% of women in the study and only 19.7% of the men (p less than 0.005). The percutaneous insertion of the IABP is recommended as the technique of choice because of the ease of insertion, lack of infectious complications, and similar rate of major ischemic complications when compared with IABPs inserted by open surgical means through a graft anastomosed to the common femoral artery.

Coronary Disease↗
PubMed1985

Infectious complications and cost-effectiveness of open resuscitation in the surgical intensive care unit after cardiac surgery.

From July, 1982, to May, 1984, 2,412 patients underwent cardiac surgery. Open resuscitation through a midline sternotomy was performed in the surgical intensive care unit (SICU) 88 times in 64 patients one minute to 10 days after admission. There were 49 initial survivors; 31 patients had primary closure in the SICU (Group 1), and 18 patients had delayed closure (Group 2). In Group 1 there was 1 death. Wound infection developed in 2 of the 30 survivors--Escherichia coli in 1 and Staphylococcus epidermidis in 1. The latter required subsequent debridement. In Group 2 there were 8 survivors and no wound infections. Fifteen patients could not be resuscitated because of ventricular arrhythmia (13%), asystole (33%), cardiogenic shock (47%), and tamponade (7%). Only 2 of 38 patients, or 5%, experienced wound infections. This study demonstrates that open resuscitation in the SICU is a safe, rapid, and cost-effective procedure that will allow earlier intervention, diagnosis, and treatment. In no instance was death attributed to wound infection, and at our institution, this method resulted in cost savings of more than $1,000 per patient.

Adult↗
PubMed1984

Coronary arteriography as an aid in left atrial myxoma diagnosis.

In two cases of left atrial myxoma, coronary arteriography was helpful in the diagnosis because the angiogram showed "true" tumor vascularity, which differs from neovascularization seen in an organized thrombus. One patient had a small, highly vascular tumor in which echocardiography was not diagnostic. Coronary arteriography may be an important diagnostic aid for delineating intracardiac myxomas.

Aged↗
PubMed1984

Use of the BioMedicus centrifugal pump in traumatic tears of the thoracic aorta.

Traumatic blunt thoracic aortic injury is a clinical entity of increasing incidence. After the diagnosis of traumatic tear of the aorta is made, there is some controversy over whether the aorta should be repaired using cardiopulmonary bypass, a heparinized shunt, or cross-clamping and graft interposition without a shunt or bypass. At Allegheny General Hospital, 19 patients were treated for traumatic tears of the thoracic aorta between July 1, 1977, and June 30, 1983. They can be divided into two groups: Group 1 (July 1, 1977, through October 31, 1981), in which no shunt or bypass or only a heparinized shunt was used, and Group 2 (November 1, 1981, through June 30, 1983), in which left atrium-femoral artery bypass was performed using a BioMedicus heparinless pump and tubing. Among the 10 patients in Group 1, 4 died and 2 had paraplegia postoperatively. Among the 9 patients in Group 2, 1 died and none experienced paraplegia following operation. We believe that the BioMedicus centrifugal pump is a simple, safe means of perfusing the lower body, kidneys, and spinal column without necessitating heparinization in a patient with multiple injuries or the placement of a cumbersome heparinized shunt. Because of the simplicity and the reliability demonstrated, this pump should be considered for use in all patients with traumatic tears of the thoracic aorta.

Adolescent↗
PubMed1982

Catamenial pneumothorax: the roles of diaphragmatic defects and endometriosis.

The diagnosis of catamenial pneumothorax should be suspected whenever a women in the third or fourth decade of life has recurrent right-sided chest pain temporally associated with menstruation. This entity was first described in 1958 and since then, 59 cases have been reported in the English literature. There is no universally accepted explanation for the pathogenesis of the pneumothorax. Four additional cases are presented which support the significant role that diaphragmatic defects and endometriosis play in the pathogenesis of catamenial pneumothorax. At thoracotomy, numerous small perforations of the right diaphragm were found in three patients, two of whom had associated endometriosis of that diaphragm. The fourth patient had indirect evidence of diaphragmatic defects proven by a diagnostic pneumoperitoneum. On the basis of the hypothesis of transfallopian passage of air, this patient was treated by tubal ligation only and has not had a recurrence of pneumothorax since. This form of therapy has not been reported previously for this disorder.

Adult↗
PubMed1981

Improved myocardial protection with nifedipine and potassium-based cardioplegia.

Thirty dogs were studied acutely on cardiopulmonary bypass in four groups. Hearts in Groups 1C (standard cardioplegia, n = 5) and 2c (n = 10) were subjected to periods of global ischemia of 1 and 2 hours, respectively. Both groups received 300 cc boluses of hypothermic (4 degrees C), potassium-based cardioplegic solution infused via an 18 gauge needle proximal to the aortic cross-clamp, at every 30 minute interval of ischemia. Groups 1CN (standard cardioplegia plus nifedipine, n = 5) and 2CN (n = 10) were treated similarly, except that nifedipine (5 microgram/kg) was added to each 300 cc bolus of cardioplegic solution. The addition of nifedipine in Groups 1CN and 2CN resulted in statistically significant reduction in myocardial water content (p less than 0.005), mean left atrial pressure (MLAP) (p less than 0.05), and myocardial compliance (p less than 0.005) as compared to the control groups (1C and 2C). Recovery of left ventricular dp/dt in Experimental Group 2CN was also statistically better (p less than 0.025) than in Control Group 2C. Examination of myocardial biopsy tissue by electron microscopy was not conclusive. Nifedipine used in combination with hypothermic, potassium-based cardioplegia provided significant additional myocardial protection over cardioplegia alone.

Animals↗