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Biomedical subjects

W C Scott

Publications and source records attributed to W C Scott.

At least 19 recordsLinked to original sources
PubMed1986

Improved lung preservation using Euro-Collins solution for flush-perfusion.

Satisfactory extended preservation of the lung has been difficult to obtain. This study investigated the influence of different total volumes and flow rates during flush-perfusion of the lung, and their effect on pulmonary artery pressure, flow distribution, regional lung temperature and functional performance of the lungs following transplantation after 24 hours. Fifteen mongrel dogs served as donors of the heart and lung block. Cold modified Euro-Collins solution was used as flush perfusate. Pulmonary artery and perfusion-line pressures were measured. The regional lung temperature was measured at one minute intervals with 5 myocardial temperature probes. Flow distribution was determined with micro-aggregated albumin labelled with Technetium 99. The heart-lung block was harvested, the right lung removed, and samples taken for gamma-counting. The left lung was stored in cold Euro-Collins solution and then transplanted. The inspired oxygen fraction (FiO2) was set at 0.4 and was kept constant throughout the procedure and the entire postoperative course. There were 3 groups of 5 animals each. In group A, the flush perfusate was administered at a total volume of 20 cc/kg over a period of 6 minutes. In group B the same volume of perfusate was administered at a pulmonary artery pressure (PAP) of 18 to 20 mmHg, resulting in a considerably shorter perfusion time (1.3 minutes). In group C 60 cc/kg of perfusate were given at the same flow rate as in group B, also resulting in PAP of 18 to 20 mmHg, but the perfusion time was increased to 4 minutes. Thus, groups B and C investigated the effect of increased pressure and volume of perfusate, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Twenty years of lung preservation--a review.

Preservation of the lung remains a major challenge and hinders the development of distant lung and heart-lung block procurement, limiting the clinical application of these modalities. The progress made in the field of lung preservation is reviewed and the many unanswered problems are presented here.

Animals↗
PubMed1985

Long-term hemodynamics following combined heart and lung transplantation in primates.

To assess the long-term hemodynamic consequences of combined heart and lung transplantation, we investigated six rhesus monkeys 2.6 to 4.6 years (mean 4.0) after operation. Total follow-up was 24.0 primate-years. Autotransplantation had been carried out in four animals and allotransplantation in two, and the hemodynamic results were compared with those in three normal monkeys of similar size. Each animal underwent simultaneous right and left heart catheterization and pulmonary arteriography. Hemodynamic measurements were made at three levels of inspired oxygen. Arterial oxygen tension was within normal limits in all animals, and pulmonary artery pressure and pulmonary vascular resistance index did not change significantly with changes in the levels of inspired oxygen. Indices of left ventricular systolic function were normal in all animals. Values for pulmonary artery pressure and pulmonary vascular resistance index were similar in the autograft and normal groups: in the allograft group, the average pressure was 30/17 mm Hg (mean 24) and the index was 5.6 units . m2--both levels significantly higher than normal (pressure was 16/10 mm Hg, mean 13, [p less than 0.001] and index was 2.5 units . m2 [p less than 0.02]). Pulmonary arteriography in the allograft group with the highest pulmonary vascular resistance index (6.1 units . m2) was compatible with pulmonary vascular disease. Pulmonary arteriograms in the remaining eight monkeys were normal. Prolonged survival following combined heart and lung transplantation is possible in primates. Autotransplantation (and probable persisting denervation of the cardiopulmonary axis) does not necessarily result in abnormal long-term hemodynamics. The elevation in pulmonary artery pressure and pulmonary vascular resistance index in the allograft group may be related to previous episodes of pulmonary rejection, infection, or drug reaction.

Animals↗
PubMed1985

Acute and chronic aortic dissections--determinants of long-term outcome for operative survivors.

A total of 135 survivors of surgical treatment of aortic dissection was followed for up to 15 years after surgery. Actuarial survival rates were 82 +/- 4% at 5 years and 64 +/- 6% at 10 years. There were no significant differences in long-term survival rates of patients in four subsets based on type and acuity of dissections. The incidence of late reoperation (dissection-related) was 13 +/- 4% at 5 years and 23 +/- 6% at 10 years; again, there was no significant difference among patients with different types or acuity of dissection. Multiple variables were investigated by multivariate discriminant analysis. Significant independent risk factors for late death included stroke, chronic renal dysfunction, remote myocardial infarction, and operation in the early years of this study. Younger age, site of intimal tear (arch), and cardiac tamponade portended a significantly higher likelihood of late reoperation. Except for stroke, no complication of the dissection or intraoperative factor significantly influenced late survival. Patients in whom the intimal tear was located in the aortic arch had the highest probability of late reoperation. Thus, dissection type, acuity, and distal extent, whether or not the tear was resected or concomitant aortic valve replacement performed, and a host of patient-related characteristics had no significant influence on the generally excellent long-term prognosis after surgical treatment. Indefinite surveillance of the remaining natural aorta is imperative (with reoperation when indicated) to attain such results.

Actuarial Analysis↗
PubMed1985

Determinants of operative mortality for patients undergoing aortic valve replacement. Discriminant analysis of 1,479 operations.

The influence of 35 preoperative and intraoperative characteristics on operative mortality risk after 1,479 isolated aortic valve replacement procedures (1967 to 1981) was investigated utilizing univariate and multivariate logistic regression analyses. Mean age at operation was 58 +/- 13 years; 72% of patients were men. Physiology was classified as aortic stenosis (58%), regurgitation (30%), or both (9%). The overall operative mortality rate was 7% +/- 1%, but there were substantial differences in operative mortality rates among physiological subgroups (aortic regurgitation, 10% +/- 2%; aortic stenosis, 6% +/- 1%; stenosis/regurgitation, 5% +/- 2%). Independent determinants of operative mortality rate in the entire group were advanced New York Heart Association functional class, renal dysfunction, physiological subgroup, atrial fibrillation, and older age. In the aortic regurgitation subgroup, functional class, atrial fibrillation, and operative year were independent predictors. In the aortic stenosis subgroup, the significant determinants were functional class, renal dysfunction, age, prosthetic valve dysfunction, and absence of angina. Concomitant coronary bypass grafting, previous operation, endocarditis, and ascending aortic replacement had no independent predictive effect on operative mortality rate. Thus, the early results of aortic valve replacement can be related to several specific variables describing the functional and physiological status of the patient. Operative mortality rate is not independently related to previous operation or concomitant operative procedures. Specific differences in risk factors exist among the various physiological subgroups, probably reflecting the pathophysiology of the different hemodynamic lesions. This information should provide for a more rational approach to aortic valve replacement, at least in terms of early risk/benefit deliberations.

Adult↗
PubMed1985

Operative risk of mitral valve replacement: discriminant analysis of 1329 procedures.

The influence of 34 variables on the operative mortality rate for isolated mitral valve replacement (MVR) was assessed by univariate and multivariate logistic regression analysis. The physiologic lesions were classified as stenosis (20%, operative mortality rate 8 +/- 1%), regurgitation (44%, operative mortality rate 13 +/- 2%), and mixed (34%, operative mortality rate 8 +/- 1%). Functional class (NYHA), previous myocardial infarction, and hepatic dysfunction were powerful independent clinical determinants of operative mortality (p less than .001), along with age at operation and emergency operation (p = .001, p = .04). Concomitant coronary artery bypass grafting or tricuspid annuloplasty, angina, ischemic etiology, and physiologic lesion were not significant independent determinants of operative risk. Interestingly, year of operation, prosthetic valve dysfunction, and previous cardiac surgery had no important effect on operative mortality. Early operative risk for MVR was related to preoperative cardiac and hepatic function. Prior myocardial infarction substantially increased the risk even if the mitral valve disease was not ischemic in origin. Increased operative mortality rate in the subgroup with mitral regurgitation was related to advanced left ventricular failure and myocardial infarction rather than the etiology of the mitral regurgitation. These clinical factors coupled with more refined measurements of left ventricular systolic pump function (independent of loading conditions) should permit more intelligent decision making regarding the optimal timing of MVR, at least in terms of early operative risk.

Adult↗
PubMed1979

Hemodynamic effects of various modes of cardiac pacing after operation for idiopathic hypertrophic subaortic stenosis.

The hemodynamic effects of varying heart rate and pacing site were studied in 6 patients with idiopathic hypertrophic subaortic stenosis following operative relief of outflow obstruction. Ventricular pacing (117 beats per minute) resulted in a 26% decrease in cardiac output (p less than 0.02), a 54% increase in pulmonary capillary wedge pressure (p less than 0.03), and a 23% decrease in mean blood pressure (p less than 0.05), compared with normal sinus rhythm (88 beats per minute). Slow atrial pacing (112 beats per minute) did not significantly alter any hemodynamic variable compared with normal sinus rhythm. Rapid atrial pacing (143 beats per minute) produced a similar degree of hemodynamic impairment as ventricular pacing. This study demonstrates that ventricular pacing at heart rates commonly used clinically and rapid atrial rates result in a significant fall in cardiac output. Preservation of atrial systole at heart rates that allow adequate diastolic ventricular filling of a hypertrophied, noncompliant ventricle is stressed. In addition, atrial electrodes are useful to record atrial electrograms or induce rapid atrial stimulation to treat supraventricular tachyarrhythmias.

Adult↗
PubMed1978

Pelvic abscess in association with intrauterine contraceptive device.

Serious pelvic infection associated with the use of IUDs is of increasing concern to obstetricians and gynecologists. This review of the literature is accompanied by analysis of 5 years' experience at the Arizona Health Sciences Center. Of 169 patients with acute infections, 34% had an IUD in place at the onset of infection. In addition, 24 of the patients were less than 20 years of age and 35% were nulliparous. Of the nulliparous patients, 11 were rendered sterile following surgical extirpative therapy. Sixty-six patients developed pelvic and tubo-ovarian abscesses; 38% of those were related to IUD usage. Six of the pelvic abscesses and eight of the unilateral tubo-ovarian abscesses came to pelvic cleanout. Evidence presented documents the serious infection potential that IUD usage entails, the antibiotic and surgical management, the infertility that results, and the mechanism assumed responsible. In addition, the high-risk patient has been identified (young, nulliparous, sexually active, and, especially, of the lower socioeconomic strata).

Abscess↗
PubMed1978

Limits of myocardial protection with potassium cardioplegia.

Preservation of left ventricular function with various potassium-based cardioplegic solutions has been considered to be effective for at least 60 minutes during occlusion of the ascending aorta. The purpose of this study was to define the limits of protection offered by potassium alone. A single bolus of 150 ml of potassium (24 mEq per liter) in normal saline solution at 30 degrees C was injected in the aortic roots of foxhounds at the initiation of periods of 45 minutes, 60 minutes, and 75 minutes of aortic occlusion at a core temperature of 30 degrees C. Data derived from postischemic recovery phase ventricular function curves and force-velocity relations demonstrated excellent protection during 45 minutes of ischemia, inconsistent protection at 60 minutes, and poor protection at 75 minutes.

Animals↗