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Biomedical subjects

R W Stewart

Publications and source records attributed to R W Stewart.

At least 55 records · Page 3Linked to original sources
PubMed1990

J. Maxwell Chamberlain memorial paper. Sternal wound complications after isolated coronary artery bypass grafting: early and late mortality, morbidity, and cost of care.

Of 6,504 consecutive patients who underwent isolated coronary bypass grafting in 1985 to 1987, 72 (1.1%) patients experienced sternal wound complications. Ten patients (14%) with wound complications died of multi-system failure. Only the patients with negative cultures fared well; of the bacterial culture categories, polymicrobial infection carried the worst prognosis. Effects of recurring infection were seen throughout the first year. Patients, grouped according to conduits received, experienced these wound complication rates: vein grafts only, 11/1,085 (1.0%); one internal thoracic artery, 38/4,073 (0.9%); and bilateral internal thoracic artery grafts, 23/1,346 (1.7%). There were no significant differences in wound complication rates between primary and reoperation patients or among conduit groups. By logistic regression analysis, the relative risk for patients with diabetes and bilateral internal thoracic artery grafting was 5.00 (95% confidence interval, 2.4 to 10.5). Operation time as a continuous variable increased the relative risk of wound complication 1.47 times per hour (1.3 to 1.7); obesity, 2.90 times (1.8 to 4.8); and blood units as continuous variable, 1.05 times per unit (1.01 to 1.10). Bilateral internal thoracic artery grafting in nondiabetic patients carried no greater risk of wound complication than that in patients with vein grafts only or with one internal thoracic artery graft.

Aged↗
PubMed1990

Reoperation for coronary atherosclerosis. Changing practice in 2509 consecutive patients.

We analyzed trends in clinical, angiographic, and operative variables and documented long-term survival in 2509 consecutive patients who underwent reoperation for myocardial revascularization at The Cleveland Clinic during a 20-year period (1967 to 1987). The patients were grouped into four cohorts by year of surgery. This analysis showed that vein graft atherosclerosis has become the leading indication for reoperation, and patient age and interval between operations continue to increase. Mortality rates ranged from 2% to 5% and, despite increasing comorbidity, more extensive coronary atherosclerosis, and worse left ventricular function, the hospital mortality rate was 2.9% from 1985 to 1987. Perioperative new Q-wave myocardial infarction occurred in 7% to 8% of patients from 1967 to 1984 but decreased to 4% in the 1985 to 1987 period (p = 0.04). Internal thoracic artery graft usage in reoperations increased from 27% in the 1967 to 1978 period to 67% in the 1985 to 1987 period. Advanced age and presence of left main coronary artery disease adversely influenced late survival more consistently than other factors. Patients operated on in 1967 to 1978 had fewer risk factors, which explains their higher survival rate compared with more recent cohorts. Factors associated with improved 10-year actuarial survival included age younger than 65 years, mild angina, no major comorbidity, no left main coronary artery disease, good left ventricular performance, and an internal thoracic artery graft.

Coronary Artery Disease↗
PubMed1990

Kluyvera mediastinitis following open-heart surgery: a case report.

Reports of serious infections caused by Kluyvera spp. have been rare. A case of Kluyvera sp. mediastinitis and bacteremia in a man after open-heart surgery is described. The clinical significance of Kluyvera sp. isolates was debated in early descriptions of the organism. More recent reports, as well as the present case, suggest that the pathogenic potential of this organism is being increasingly recognized by clinicians and microbiologists.

Aged↗
PubMed1990

Inotropic effects of angiotensin II on human cardiac muscle in vitro.

The direct effects of angiotensin II (Ang II) on human cardiac muscle were investigated using isolated trabecular muscles from failing and functionally normal hearts. Atrial and ventricular trabeculae were studied. Results demonstrated a positive inotropic effect of Ang II on human cardiac muscle. Comparison of the effects of Ang II among groups indicated that the responsiveness tended to be greater in atrial and normal muscle compared with failing muscle. Results of this study also demonstrated heterogeneity in the responsiveness to Ang II among human muscles, which was not correlated with patient age, sex, diagnosis, prior treatment with angiotensin converting enzyme inhibitor, or heart function. A significant correlation between response to Ang II and response to isoproterenol was demonstrated in failing ventricular trabeculae, which may suggest that defects in beta-adrenergic responsiveness in the failing human ventricle are accompanied by a loss of responsiveness to Ang II. Studies were extended to the Syrian cardiomyopathic hamster and its control. A dose-dependent inotropic response occurred in normal hamster ventricular muscle but was significantly diminished in cardiomyopathic muscle. Ang II did not shorten the timing of contraction, and pretreatment with adrenergic-blocking agents did not shift the dose-response curve, indicating that the response was not cyclic AMP mediated. This study demonstrates for the first time that Ang II can exert an inotropic effect directly on human cardiac muscle and confirms that there is a direct effect of Ang II on hamster cardiac muscle. The study further suggests, however, that the inotropic response to Ang II in cardiac muscle is heterogeneous and may be diminished by heart failure.

Angiotensin II↗
PubMed1990

Angiotensin II-forming pathways in normal and failing human hearts.

Reduced preload and afterload to the heart are important effects of angiotensin converting enzyme (ACE) inhibitors in the treatment of congestive heart failure. However, since angiotensin II (Ang II) directly increases the strength of myocardial contraction, suppression of Ang II formation by ACE inhibitors could potentially reduce the beneficial effects of Ang II on the failing heart. To study how ACE inhibition suppresses cardiac Ang II formation in man, we characterized ACE-dependent and ACE-independent Ang II-forming pathways in eight normal and 24 failing human hearts obtained at cardiac transplantation. Ang II-forming activity in left ventricular (LV) membrane preparations was assessed by measuring the conversion of [125I]angiotensin I (Ang I) to [125I]Ang II. LV [125I]Ang II-forming activity in normal hearts (35.5 +/- 2.7 fmol/min/mg, n = 8) was not different from that in hearts from patients with ischemic cardiomyopathy (25.5 +/- 2.9 fmol/min/mg, n = 9) and was 48% lower (p less than 0.001) in hearts from patients with idiopathic cardiomyopathy (18.5 +/- 1.9 fmol/min/mg, n = 15).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Endothelin is a positive inotropic agent in human and rat heart in vitro.

We have investigated the response to endothelin of isolated atrial and ventricular trabeculae from failing human hearts obtained at transplant. Results indicate that endothelin exerts a significant positive inotropic effect on human atrial and ventricular tissue, with increases in developed tension of 74.6 +/- 14.1% (+/- SEM) and 9.9 +/- 4.0%, respectively. Further studies on rat cardiac muscle demonstrate that the greater inotropic effect on atrial than ventricular muscle is also exhibited by the rat heart in vitro, with 39.9 +/- 10.7% and 17.1 +/- 5.9% increases in developed tension for atria and papillary muscle, respectively. Studies in rat atria also provide no evidence for an effect of endothelin on the frequency of spontaneous contractions. These results suggest that the potential exists for regulation of cardiac function in humans and rats by endothelial-derived factors such as endothelin, possibly via augmentation of atrial systole.

Adolescent↗
PubMed1989

An evaluation of three serological tests for antibody to Brucella suis in pigs.

The Rose Bengal Plate Agglutination test (RBT), the complement fixation text (CFT) and the tube agglutination test (TAT) were applied to serums from 345 feral and 80 domestic pigs sampled at slaughter. At least 2 of the 3 serological tests were applied to each serum. Tissues from all pigs were cultured for Brucella suis and the degree of culture effort was categorised from 1 to 4 in decreasing order. Fifty-eight feral and 35 domestic pigs were culture-positive. A greater proportion of culture-positive pigs was obtained for category 1 and 2 culture effort. Tissues yielding B. suis most often were mandibular, gastrohepatic and external iliac lymph nodes, spleen and various abdominal organs. Infection in domestic pigs was associated with exposure to feral pigs. The sensitivity (Se) in culture-positive pigs of the RBT (79.1%) was significantly greater than that of either the CFT (49.1%) or TAT (51.1%). The specificities (Sp) in culture-negative pigs were 81.2% for the RBT, 90.8% for the CFT and 81.0% for the TAT. A more realistic estimate of Sp for the RBT was considered to be 97.6%, based on serological results from 31,326 domestic pigs routinely tested for regulatory purposes. The RBT was clearly superior to the other 2 tests in this study. However, a more sensitive screening test would be preferable for use in a test and slaughter eradication program. The RBT would be a suitable confirmatory test.

Agglutination Tests↗
PubMed1989

Angiotensin II receptors in normal and failing human hearts.

To demonstrate the existence and help clarify the function of angiotensin II (Ang II) receptors in the human heart, we characterized the cardiac Ang II receptor and examined the levels and distribution of ventricular Ang II receptors in normal (n = 6) and failing (n = 14) hearts. Ang II receptors were characterized using the Ang II receptor agonist [125I]Ang II. Cardiac [125I]Ang II-binding sites were of high affinity (Kd, approximately 1 nmol/L) and low capacity (Bmax, approximately 3 fmol/mg membrane protein) and were pharmacologically specific [IC50 values for Ang II, [Sar1,Ile8]Ang II, and Ang III were 1.2, 3.0, and 400 nmol/L, respectively; the inactive Ang II metabolite Ang-(1-5), at a concentration of 1 mumol/L, inhibited [125I]Ang II binding by less than 10%]. These characteristics of cardiac [125I]Ang II-binding sites are similar to those of previously characterized mammalian heart Ang II receptors. In normal adult donor hearts (n = 5), Ang II receptor density in the left ventricle [LV, 2.90 +/- 1.40 (+/- SE) fmol/mg] was similar to that in the right ventricle (RV, 3.82 +/- 1.10 fmol/mg). The ventricular Ang II receptor density in adult patients with idiopathic (LV, 1.77 +/- 0.35 fmol/mg; RV, 1.58 +/- 0.29 fmol/mg; n = 8) or dilated cardiomyopathy (LV, 2.00 +/- 0.58 fmol/mg; RV, 2.56 +/- 0.52 fmol/mg n = 5) was similar to that in the normal heart. Ventricular Ang II receptors, localized by autoradiography using the Ang II receptor antagonist [125I]-[Sar1,Ile8]Ang II, were consistently found in the myocardium, cardiac adrenergic nerves, and coronary vessels of normal and failing ventricles. In human ventricles Ang II receptor levels were not correlated with age. Because ventricular Ang II receptor density in a normal neonatal human heart and that in a heart from an adolescent patient with idiopathic cardiomyopathy were more than 10-fold and more than 5-fold higher, respectively, than in normal adult ventricles, we investigated whether postnatal changes occur in ventricular Ang II receptors in rats. In male and female rats ventricular Ang II receptor density was about 2-fold higher in 1-day-old rats compared to that in 10-day-old or peripubertal rats. These data suggest developmental regulation of ventricular Ang II receptors. Our findings suggest that direct and neural angiotensinergic inputs to the myocardium play a role in the regulation of cardiac function in man and that these inputs are preserved in the failing heart.

Adolescent↗
PubMed1989

Decreased infections in cardiac transplant recipients on cyclosporine with reduced corticosteroid use.

Fifty patients undergoing orthotopic cardiac transplantation were monitored over 34 months for evidence of infection. Four separate immunosuppressive protocols were used during the course of the study; the most recent protocol (protocol 4) employed significantly lower overall steroid dosages than the earlier protocols (protocols 1,2, and 3). All immunosuppressive regimens used cyclosporine, and azathioprine was added in the last three protocols. Statistical techniques to compare the occurrence of infection in protocols 1,2, and 3 v protocol 4 showed that patients in protocol group 4 (n = 21) had significantly more time free of pneumonia (P = .02) and major infections (P = .04) and marginally more time free of symptomatic cytomegalovirus infection (P = .08) than patients in protocol groups 1, 2, and 3 (n = 29). The median incidence of major infection per month was lower for protocol group 4 (P = .02). The time free of viral infection did not differ significantly between the two groups (P = .75) nor did the median incidence of rejection per month (P = .19). The authors conclude that reduction of steroid dosages in cardiac transplant patients receiving cyclosporine is associated with a significant decrease in the incidence of clinically important infections.

Adrenal Cortex Hormones↗
PubMed1989

Primary isolated aortic valve replacement. Early and late results.

A total of 1689 consecutive patients underwent isolated aortic valve replacement at the Cleveland Clinic Foundation from 1972 through 1986. There were 57 (3.4%) in-hospital deaths. Multivariate analysis identified advanced age (p = 0.0014), preoperative blood urea nitrogen level greater than 25 mg/100 ml (p = 0.008), New York Heart Association function class (p = 0.015), and preoperative atrial fibrillation (p = 0.04) as independent variables associated with increased in-hospital mortality and the use of cardioplegia for myocardial protection (p = 0.006) as a factor decreasing mortality. Follow-up documented survival rates of 85% and 66% and event-free survival rates of 71% and 43% at 5 and 10 postoperative years, respectively. Advanced age, moderate or severe impairment of left ventricular function, coronary artery disease, and preoperative blood urea nitrogen level greater than 25 mg/100 ml were associated with decreased late survival and event-free survival (all p less than 0.05). Patients with bioprostheses had better survival (p = 0.003) and event-free survival (p = 0.0007) rates than patients with mechanical valves. Patients with bioprostheses had superior results only if not receiving warfarin, and they experienced more reoperations and endocarditis; those with mechanical prostheses had more strokes, myocardial infarctions, bleeding complications, and thromboembolic events. Analysis of patients grouped according to age at operation showed that bioprostheses were associated with improved survival and event-free survival for patients 40 years older or older. Younger patients experienced more reoperations and episodes of endocarditis, and older patients more thromboembolic complications. We conclude that 10-year results after isolated aortic valve replacement are influenced by both patient-related and management-related variables, and the impact of these factors is different for patients of different ages.

Adult↗
PubMed1989

Ventricular aneurysm resection. Trends in surgical risk.

From 1972 to 1987, 1,183 patients underwent ventricular aneurysm resection. At 4-year intervals, this series was divided into four subsets that differed in patient and management-related variables. Comparison of patients seen from 1972 to 1975 with those seen in 1984-1987 shows a significant increase in mean age to 59.4 years, with 31.6% older than 65 years, an increase to 43.4% of patients with congestive heart failure, and a decrease to 42.8% of patients with angina. In the most recent interval, 30.7% of patients had mammary grafts, 81.1% had associated grafts, and 47.2% of patients were completely revascularized. Mortality rate, however, increased to 8%. Deaths were attributed to cardiac causes in 59.7% of cases. Multivariate analysis identified emergent procedures, advancing age, left main trunk disease, and history of congestive heart failure as risk factors. We conclude that the incidence of aneurysm resection is decreasing and operative risk has been constant despite advancing patient age and more extensive operative procedure.

Aged↗
PubMed1988

Applicability of mitral valvuloplasty techniques in a North American population.

Records of 520 patients who underwent mitral valve operations were reviewed to determine the pathophysiology, etiology, anatomy of the valve lesion and use of valvuloplasty techniques. Pure mitral regurgitation, present in 269 patients (52%), was the most common lesion while rheumatic valvulitis, seen in 286 patients (55%), was the most common etiology. Degenerative lesions were found in 168 patients, 33% of the total and 63% of the pure mitral regurgitation group. Two-hundred seventy patients (52%) were treated with valvuloplasty techniques. The incidence of reconstructive procedures was determined for each of the various patient subsets. Overall hospital mortality was 5.6% in the series: 8.4% for mitral replacement compared with 3% for mitral valvuloplasty (p = 0.007). Among patients undergoing primary isolated mitral procedures, hospital mortality for replacement was 7.5% compared with 1.4% for valvuloplasty (p = 0.018). Mitral valvuloplasty seems to provide a therapeutic alternative applicable to the spectrum of mitral valve pathology seen in a North American population.

Female↗
PubMed1988

A multivariate analysis of the risk of cytomegalovirus infection in heart transplant recipients.

Thirty-four consecutive heart transplant recipients were studied over a two-year period for evidence of cytomegalovirus (CMV) infection. Twenty-three episodes of CMV infection were identified; 19 of these occurred within 120 d after transplantation and were statistically analyzed. Fifteen potential risk factors were evaluated, including the following: pretransplant CMV serological status of donor and recipient; recipient's age, sex, race, and cardiac disease; number and type of blood products transfused; type and intensity of immunosuppression; occurrence of rejection; and leukopenia. The Cox proportional hazards model identified both greater than average steroid dosage and positive recipient CMV serology as significant risk factors for CMV infection (P = .014 and .048, respectively). In a separate analysis, however, only greater than average steroid dosage was associated with clinically significant CMV infection (P = .005).

Adrenal Cortex Hormones↗
PubMed1988

A multivariate analysis of risk factors for pneumonia following cardiac transplantation.

Fifty cardiac transplant recipients were followed over a 34-month period for evidence of pneumonia that developed in twelve patients. Potential risk factors evaluated fell into three categories: demographic (age, sex, race, and underlying cardiac disease); pretransplant status (hospitalized, intubated, pulmonary infiltrate, requirement for antibiotics, or the need for a ventricular assist device); and posttransplant therapy (amount and type of blood products, prolonged endotracheal intubation or reintubation, use of ventricular assist devices, immunosuppressive protocols, lymphocyte subset ratios, and occurrence of rejection, leukopenia, or CMV infection). The Cox proportional hazards model identified posttransplant reintubation (P = 0.009) and the use of protocols employing larger steroid dosages (P = 0.02) as significant risk factors for pneumonia. In a separate analysis, the occurrence of pneumonia was shown to be a significant risk factor for mortality (P = 0.018).

Heart Transplantation↗
PubMed1988

Intrathecal papaverine for the prevention of paraplegia after operation on the thoracic or thoracoabdominal aorta.

Eleven patients undergoing operation on the descending or thoracoabdominal aorta were administered papaverine intrathecally in an attempt to protect the spinal cord from ischemic damage. Concurrently, 19 patients, also undergoing operation on the thoracic or thoracoabdominal aorta, were operated on with a variety of conventional techniques, including distal aortic perfusion, but were not given intrathecal papaverine. No signs of early neurologic injury developed in any of the patients in the intrathecal papaverine group, although delayed paraparesis developed in one of the patients (9%; 70% confidence limits = 1% to 28%). On the other hand, eight of 19 patients undergoing operation with conventional techniques had either lower extremity paraparesis or paraplegia postoperatively (42%; 70% confidence limits = 29% to 57%; p = 0.058). Intrathecal papaverine appeared to provide spinal cord protection during thoracic aortic operations, particularly during prolonged periods of aortic cross-clamping. Papaverine was not associated with increased risk and may be superior to other conventionally used modalities. We conclude that continued evaluation of this technique is justified.

Adult↗