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Biomedical subjects

A Starr

Publications and source records attributed to A Starr.

At least 37 records · Page 2Linked to original sources

Time-related analysis of nonfatal heart valve complications: cumulative incidence (actual) versus Kaplan-Meier (actuarial).

BACKGROUND: The cumulative incidence of a postoperative event is the percentage of patients who experience the event by postoperative time T. Its complete determination requires all patients to be followed until T. In ongoing series, the Kaplan-Meier method is employed because not all patients have been observed until T. When applied to nonfatal events, however, the Kaplan-Meier estimates probabilities as if the patients who die before they sustain an event continue to be at risk thereafter. It thus estimates risk in the unrealistic situation where death does not occur. METHODS AND RESULTS: Cumulative incidence can be estimated directly, to provide the probability of actually experiencing an event before death, that is, when death properly eliminates patients from further risk of the event. We compare cumulative incidence and Kaplan-Meier estimates in two series of mitral valve replacement patients: thromboembolism in a completed series of ball valves implanted in relatively young patients and valve explant in an ongoing series of porcine valves in older patients. Kaplan-Meier estimated a higher event percentage than the cumulative incidence, and the difference was greater in the older patients, who had a higher death rate. CONCLUSIONS: Cumulative incidence, unlike Kaplan-Meier, provides estimates of the percentage of patients who will actually sustain an event. Cumulative incidence is more meaningful for individual patient counseling and more useful for estimating resource utilization in a managed population.

Aged

Reduction in costs, blood products, and operating time in patients undergoing open heart surgery.

OBJECTIVE: To test the hypothesis that use of aprotinin at hall dose would be more cost-effective or as efficacious as full-dose aprotinin or no aprotinin during open heart surgery. DESIGN: Cost-effective analysis, unmasked prospective comparison. SETTING: Community hospital. PATIENTS: One hundred thirty-three patients undergoing open heart surgery. INTERVENTIONS: Patients in 3 consecutive groups undergoing open heart surgery were allocated to receive no aprotinin, full-dose aprotinin, or half-dose aprotinin. MAIN OUTCOME MEASURES: Total cost (in dollars) of blood products administered plus cost of aprotinin at various dosages, comparison of total blood products administered during hospitalization, and closure time required in the operating room. RESULTS: Full-dose and half-dose aprotinin significantly (P < .05) reduced the total blood products administered during hospitalization and the operating room closure time. However, use of half-dose aprotinin resulted in a significant cost savings (P < .05) when compared with either the cost of blood products required in the nodose aprotinin group or the cost of blood products plus aprotinin in the full-dose aprotinin group. CONCLUSION: Use of aprotinin at half dose in a community hospital resulted in a significant reduction in costs, blood product use, and operating room closure time in patients undergoing open heart surgery.

Aged

Commissurotomy and bileaflet pericardial augmentation-resuspension for bicuspid aortic valve stenosis.

We describe a valve reconstruction technique for congenital bicuspid aortic valve stenosis employing a commissurotomy, resection of raphe between conjoint leaflets, and bileaflet augmentation-resuspension using a triangular strip of glutaraldehyde-preserved autologous pericardium. This maneuver relieves aortic valve stenosis, preserves the native valve leaflets, reproduces the natural trileaflet scalloping of the aortic valve annulus, and improves cusp coaptation.

Aortic Valve Stenosis

Glucose control lowers the risk of wound infection in diabetics after open heart operations.

BACKGROUND: Elevated blood glucose levels in the postoperative period are associated with an increased risk of deep wound infection in diabetic individuals undergoing open heart operations at Providence St. Vincent Hospital. METHODS: Of 8,910 patients who underwent cardiac operations between 1987 and 1993, 1,585 (18%) were diabetic. The rate of deep sternal wound infections in diabetic patients was 1.7%, versus 0.4% for nondiabetics. Nine hundred ninety patients had their operation before implementation of the protocol and 595 after implementation. Charts of all diabetic patients were reviewed. Mean blood glucose levels were calculated from documented results of finger-stick glucometer testing. RESULTS: Thirty-three diabetic patients suffered 35 deep wound infections: 27 sternal (1.7%) and eight at the donor site (0.5%). Infected diabetic patients had a higher mean blood glucose level through the first 2 postoperative days than noninfected patients (208 +/- 7.1 versus 190 +/- 0.8 mg/dL; p < 0.003) and had a greater body mass index (31.5 +/- 1.4 versus 28.6 +/- 0.1 kg/m2; p < 0.05). Multivariable logistic regression showed that mean blood glucose level for the first 2 days (p = 0.002), obesity (p < 0.002), and use of the internal mammary artery (p < 0.02) were all independent predictors of deep wound infection. Institution of a protocol of postoperative continuous intravenous insulin to maintain blood glucose level less than 200 mg/dL was begun in September 1991. This protocol resulted in a decrease in blood glucose levels for the first 2 postoperative days and a concomitant decrease in the proportion of patients with deep wound infections, from 2.4% (24/990) to 1.5% (9/595) (p < 0.02). CONCLUSIONS: The incidence of deep wound infection in diabetic patients was reduced after implementation of a protocol to maintain mean blood glucose level less than 200 mg/dL in the immediate postoperative period.

Aged

Repair of congenital pulmonary incompetence by bicuspidization of the pulmonary valve.

We report the successful repair of pulmonary incompetence in an adult due to the congenital absence of the posterior leaflet of the pulmonary valve. The repair consisted of bicuspidization of the pulmonary valve, which achieved competence and eliminated the symptoms and echocardiographic manifestations of right ventricular overload while preserving the native valve.

Female

Sequential changes of auditory processing during target detection: motor responding versus mental counting.

Brain potentials evoked to non-targets in an auditory target detection task changed in amplitude, duration, polarity, and scalp topography as a function of position in the stimulus sequence relative to the target. (1) A negative prestimulus readiness like-potential, or RP, the poststimulus N100, and a late slow wave to non-targets immediately after the target were reduced in amplitude compared to non-targets immediately before the target. The amplitudes of these potentials after the target then increased in size as a linear function of the number of non-targets in the sequence. (2) The amplitudes of the positive components, P50 and P200, were larger to non-targets immediately after the target than to non-targets immediately before the targets. P50 amplitude then decreased to subsequent non-targets in the sequence in a linear manner; P200 amplitude was reduced equivalently to all subsequent non-targets. (3) The duration of the P200 component could extend into the time domain when the P300 to targets would occur. The P200 component to non-targets was therefore designated 'P200/300'. The duration of the P200/300 component was shorter to non-targets immediately after the target than to non-targets immediately before the targets. P200/300 duration then extended in a linear manner to subsequent non-targets in the sequence and approached the peak latency of the P300 evoked by targets. (4) The anterior/posterior scalp distribution of P50 and the polarity of the late slow wave to non-targets changed as a function of non-target position in the sequence. The subject's response to the targets (button press or mental count) influenced these sequential effects. Linear trends for sequence were present in the press but not the count conditions for the amplitude of the RP, N100, and P300; linear trends for P50, P200/300 duration, and the late slow wave were found in both the press and count conditions. Reaction time was speeded as a function of the number of preceding targets. These dynamic changes in the processing of auditory signals were attributed to an interaction of attention and the subjective expectancies for both the appearance of a target stimulus and the requirement to make a motor response.

Acoustic Stimulation

Valve repair for aortic insufficiency: surgical classification and techniques.

OBJECTIVE: Valve repair for aortic insufficiency may provide an alternative to aortic valve replacement in selected patients. This repair could be an attempt at permanent correction or palliation to allow the aortic annulus to grow and avoid the use of anticoagulation. Based upon a five-year experience, we proposed a classification according to valvular anatomy which could be a guide to patient and procedure selection. METHODS: Between September 1989 and February 1995, 44 consecutive patients underwent aortic valvuloplasty for aortic incompetence at our institution. Patients' ages ranged from 19 months to 76 years with a mean of 33 years. The etiology of aortic incompetence was congenital in 30 patients, degenerative in 7 patients, rheumatic in 5 patients, and infective endocarditis in 2. Aortic valve lesions were classified into three different types: type I, aortic annular dilation (8 patients); type II, excessive aortic leaflet tissue (12 patients); and type III, restricted leaflet motion with or without deficient leaflet tissue (24 patients). Type I needed commissural plication in 7 patients; and aortic annuloplasty, which was simple in 6 patients, and pericardial-augmented in 2. Type II necessitated midleaflet excision in 11 patients and leaflet plication in 7. Type III required leaflet extension in 19 patients, leaflet replacement in 1 patient, aortic valve commissurotomy in 13 patients augmentation commissurorrhaphy in 2, leaflet shaving in 4, and repair of leaflet perforation in 2. RESULTS: Postoperative echocardiography revealed a significant decrease in the degree of aortic incompetence. Mean follow-up was 2.6 +/- 1.4 years. There was no mortality. Patients improved as is evident by NYHA functional class postoperatively. Eight of the first 13 patients (18%) needed reoperation. Three of these reoperations were bail-out procedures, and 3 patients (7%) who underwent the leaflet extension technique were reoperated upon 19 months to 3 years later. Presently, 23 patients are without anticoagulation, 11 take aspirin and 2 receive coumadin for combined mitral procedures. CONCLUSIONS: Aortic valve repair provides a low risk option with satisfactory intermediate-term results for the treatment of aortic insufficiency in appropriately selected patients. Patient and procedure selection may be based upon the echocardiographic anatomy of the aortic valve, and a comparative risk benefit appraisal with valve replacement.

Adolescent

Experimental facial myokymia in cat.

INTRODUCTION: The objective of this study was to describe facial myokymia in experimental animals accompanying kainic acid affects on facial motor neurons. MATERIAL & METHODS: Anesthetized cats were injected with kainic acid into the pons adjacent to the facial nucleus. Facial movements appeared shortly after the injections and facial electromyographic potentials were recorded. Cats were killed up to 4 weeks later, the brainstems were processed histologically, and the number of neurons in the facial nucleus counted. RESULTS: Cats receiving injection of kainic acid adjacent to facial nucleus all developed spontaneous writhing movements of the face ipsilateral to the injection site, clinically resembling facial myokymia in humans. Transient facial paresis, lasting several weeks, appeared in some of the cats. Facial myokymia occurred independent of histological evidence of neuronal loss in facial nucleus, whereas facial paresis occurred in all but one of the animals with significant neuronal loss in the facial nucleus. Placing a needle into the superior olive without injecting kainic acid or injections of kainic acid into cochlear nucleus was not accompanied by facial myokymia or subsequent facial paresis. CONCLUSION: Facial movements in cats similar to myokymia in humans accompanies kainic acid injections adjacent to the nucleus of the facial nerve.

Animals

Risk, diagnosis and management of prosthetic valve endocarditis: a review.

Prosthetic valve endocarditis (PVE) emerged approximately 37 years ago when the first human heart valve replacements were performed. PVE can be classified as 'early' or 'late' with the pathophysiology and etiologic organisms varying between the two subgroups. The incidence of PVE ranges up to 0.5% per patient-year for mechanical mitral valves and up to 1.0% per patient-year for other valves. The clinical presentation is similar to that of native valve endocarditis, with fever being the most prevalent sign. Diagnosis is based on a constellation of clinical signs and symptoms as well as echocardiographic evaluation of the valve and perivalvular tissues. An algorithm is set forth for diagnosis and management of patients with suspected PVE based on our personal experience and the published literature. Indications for surgery, the surgical approach and methods of PVE prophylaxis and prevention are discussed.

Algorithms

Magnetic stimulation of muscle evokes cerebral potentials by direct activation of nerve afferents: a study during muscle paralysis.

We tested the hypothesis that magnetic stimulation of muscle evokes cerebral potentials by causing a muscle contraction that then activates muscle receptors. We measured cerebral evoked potentials accompanying magnetic stimulation of muscle in 3 patients during surgery both before and after muscle paralysis with succinylcholine, a depolarizing agent. The magnetic stimulation was at low intensity (30%) and at a 2/s rate. The administration of succinylcholine sufficient to produce muscle paralysis did not alter cerebral potentials evoked by either low-intensity magnetic stimulation of muscle (gastrocnemius/soleus) or electrical stimulation of peripheral nerve (tibial nerve). In 1 normal subject, the S1 nerve root action potentials conducting at rapid velocity (> 60 m/s) were detected at the S1 foramen with a needle electrode using electrical stimulation of the tibial nerve. However, no S1 nerve root potentials could be identified to magnetic stimulation of muscle that evoked a cerebral potential. We conclude that magnetic stimulation of muscle activates terminal afferents in the muscle to provide the afferent drive for the cerebral potentials independent of muscle contraction. The failure to detect the afferent volley in S1 nerve root to magnetic stimulation suggests that only a few afferents are activated or that the activation of afferents is temporally dispersed.

Adult

Reversed bevel technique for anastomosis at the aortic arch.

We describe a method for performing the distal anastomosis in replacement of the ascending and the proximal arch of the aorta with specific attention to obtaining accurate length and orientation of the graft. This method reduces the incidence of both anastomotic dehiscence due to tension and obstruction caused by redundant graft.

Anastomosis, Surgical

Infective endocarditis: ten-year review of medical and surgical therapy.

BACKGROUND: Infective endocarditis is a complex disease process. Optimal outcome often requires both medical and surgical expertise. The need for and timing of surgical intervention is controversial and continues to evolve in parallel to advancements in diagnosis and treatment. Our experience with the treatment of infective endocarditis is reviewed herein. METHODS: A retrospective review was compiled of 140 consecutive patients who fulfilled the modified von Reyn criteria for the diagnosis of endocarditis between January 1982 and April 1992. RESULTS: Patient characteristics, symptoms, and risk factors are described. Follow-up averaged 3.5 +/- 0.8 years and totaled 491 patient-years. New York Heart Association functional class at presentation had a significant influence on survival (p < 0.0001). Long-term survival was significantly greater (p = 0.036) in patients treated medically/surgically than those treated with medical therapy alone (75% versus 54% at 5 years). Medical treatment of aortic and prosthetic endocarditis was associated with higher mortality (58% and 67%, respectively) when compared with combined medical/surgical treatment (28% and 38%, respectively). Among the survivors, New York Heart Association class at follow-up was better (p < 0.0001) in the medical/surgical group (1.05 +/- 0.04) versus the medical treatment group (1.70 +/- 0.14). CONCLUSIONS: Combined medical/surgical treatment for infective endocarditis is associated with improved survival. Patients with aortic or prosthetic endocarditis are identified as subgroups that benefit most from surgical intervention. Valvular dysfunction incited by the infective process is an important factor that should be weighed carefully in the therapeutic decision.

Adolescent

Aortic valve replacement in elderly patients: influence of concomitant coronary grafting on late survival.

BACKGROUND: Aortic valve replacement (AVR) has been an accepted therapy for elderly patients (> 70 years) with aortic valve disease. This study was designed to investigate the determinants of survival after the implantation of aortic valve prostheses, with emphasis on the effect of concomitant coronary artery bypass grafting on survival. METHODS: From November 1964 to July 1994,963 elderly patients underwent isolated AVR. Long-term survival was investigated in 877 patients (70 to 94 years) who survived operation, with 92% follow-up completeness (mean +/- standard deviation, 4.5 +/- 3.9 years; maximum, 20.1 years; total, 3,920.2 patient-years), by univariate and multivariate analyses. RESULTS: Actuarial survival was 38.1% +/- 2.8% at 10 years, 17.8% +/- 3.0% at 15 years, and 9.0% +/- 3.1% at 20 years. Eight variables (age, sex, body surface area [less or greater than 1.7 m2], period of operation, type of prosthesis, size of prosthesis, re-replacement, and concomitant coronary artery bypass grafting) were investigated with regard to long-term survival by the Kaplan-Meier method. Age, sex, and body surface area were significant. Multivariate analysis revealed that older age (p = 0.0005) and male sex (p = 0.0001) were independent variables that determined long-term survival. CONCLUSIONS: Elderly patients may have satisfactory long-term results after AVR. Age and sex are independent determinants. Other factors (such as concomitant coronary artery bypass grafting and type of prosthesis) did not independently influence long-term survival. Coronary revascularization in elderly patients with coronary disease undergoing AVR may lead to a long-term survival similar to that in patients without coronary disease undergoing AVR.

Actuarial Analysis

Primary tumors of the aorta.

Primary tumors of the aorta are rare and are usually malignant. Thirty-three cases are reported in the world literature, of which 2 are myxomas. The diagnosis is difficult and is commonly made postoperatively or at autopsy. We present a case of intraluminal aortic myxoma that presented as recurrent arterial emboli and was managed successfully. This case showed the sensitivity of magnetic resonance imaging and transesophageal echocardiography in diagnosis.

Adult

Brain potentials before and during memory scanning.

Brain potentials were recorded from 10 normal subjects engaged in a 3-item auditory verbal short-term memory task. A fixed interval (3 s) between the last memory item and the probe was compared to a random interval (1.8-4.2 s with a mean of 3 s). Subjects indicated by button press whether the probe was or was not a member of the memory-set. The same 3-item task was also presented as a counting task and required a button press to the "fourth stimulus' (the probe). The amplitudes of several slow potential shifts preceding and following the probe, and the amplitudes and latencies of the accompanying short duration components (N100, P200) were measured. When the probe appeared at a fixed interval, the amplitude of a slow negative potential in the 300 ms period preceding the probe was slightly larger in the memory than in the counting task. When the probe appeared at a random interval in the memory task, the slow negative shift preceding the probe was absent. Another slow negative shift that peaked at approximately 376 ms after the probe was present in the memory tasks but was absent in the counting task. The amplitude of a late positive shift that peaked at approximately 700 ms after the probe was not different within the memory tasks, or between the memory and counting tasks. N100 amplitude but not P200 amplitude was larger in the memory task when the probe occurred at a fixed than at a random interval. These results suggest that the amplitude of a slow negative shift preceding the probe was related primarily to a temporal expectancy for the appearance of the probe and to a lesser extent to memory processes. In contrast, a slow negative shift that followed the probe occurred only during the memory tasks.

Adult

Long-term outcome, survival analysis, and risk stratification of dynamic cardiomyoplasty.

METHODS: To analyze the long-term outcome of dynamic cardiomyoplasty, we retrospectively studied 127 consecutive patients who underwent this procedure in Paris, France (n = 76), São Paulo, Brazil (n = 37), and Portland, Oregon (n = 14). Preoperative data were collected for patients operated on between January 1985 and June 1994 and examined with respect to effect on long-term survival. Patients had a mean age of 50 +/- 13 years and were predominantly male (82%). In 46% the cause of disease was ischemic. Concomitant operations were performed in 22 patients. RESULTS: Operative mortality was 12% (15/127). Kaplan-Meier survival +/- standard error at 1 through 5 years was 73% +/- 4%, 57% +/- 5%, 49% +/- 6%, 44% +/- 6%, and 40% +/- 7%, respectively. There was a distinct improvement at 6 months in New York Heart Association functional class (3.2 +/- 0.05 vs 1.7 +/- 0.07, p < 0.0001) and a small but significant increase in left ventricular ejection fraction (20% +/- 0.8% vs 23% +/- 1.5%, p = 0.04). Ninety-day mortality was associated with low right ventricular ejection fraction, a blunted hemodynamic response to exercise testing, and requirement for an intraaortic balloon pump at the time of the operation. Using a stepwise Cox regression method of multivariable survival analysis (n = 101), we determined that atrial fibrillation, New York Heart Association class IV, high pulmonary capillary wedge pressure, and balloon pump use were independent variables simultaneously associated with poor overall survival. When metabolic testing variables were added to this model, peak oxygen consumption eliminated both pulmonary capillary wedge pressure and functional class from the model, albeit with fewer (n = 74) patients. CONCLUSION: Dynamic cardiomyoplasty is an evolving therapy for symptomatic congestive heart failure, the results of which may be enhanced by intelligent, risk-sensitive patient selection.

Cardiomyoplasty

Is referral source a risk factor for coronary surgery? Health maintenance organization versus fee-for-service system.

We began performing coronary artery bypass grafting for a large health maintenance organization (HMO) in 1974, as the sole provider of their cardiac surgery. The outcomes of our HMO group of patients were compared with those of our patients treated on a fee-for-service (FFS) basis. The HMO system entails preintervention and multidisciplinary screening conferences and is devoid of self-referral and personal financial incentives. Since 1985, the operative mortality for HMO patients has been consistently lower than for FFS patients. There were 8483 operations during this study period: 3168 (37%) were in the HMO group, with an overall operative mortality of 2.7%, and 5315 (63%) were in the FFS group, with an operative mortality of 4.6% (p=0.00002). This difference was investigated with univariate and multivariable analyses. Sixteen factors were found to univariately affect the risk of operative mortality; for five of these risk correlates there was a significant maldistribution between the HMO and FFS patients. Logistic regression was used to explore the influence of this imbalance in risk factors. The model found seven independent risk factors (left ventricular failure, emergency coronary bypass, redo bypass, nonuse of the internal thoracic artery, unstable angina, age, and diabetes) that significantly affected operative mortality. The FFS group variable closely approached independent risk significance at p=0.059. This multivariable model explained only one third of the observed differences in actual mortality between the HMO and FFS groups. The system-wide angioplasty/coronary bypass ratio, which could not be used in a patient-specific model, was 0.6 in the HMO system and 1.5 in the FFS group. Other factors related to the operating structure of a mature, large HMO may account for the remainder of the difference. The HMO referral system, through a powerful selection process, resulted in fewer emergencies, redo bypass operations, and catheterization complications that, in turn, yielded lower operative mortality than a noncoordinated FFS system of cardiovascular management.

Angioplasty, Balloon, Coronary