Search PubMed⌕ Search

Biomedical subjects

R B Karp

Publications and source records attributed to R B Karp.

At least 55 records · Page 3Linked to original sources
PubMed1987

Horizontal ventricular septum with dextroversion: hearts with and without aortic atresia.

Two hearts with horizontal ventricular septum, dextroversion (situs solitus), ventricular septal defects, and malaligned great vessels are reported. One of the hearts had aortic atresia and the infant died; the other patient had a Fontan-type physiologic correction. Reviewing the literature, the following conclusions are drawn: (a) Hearts with horizontal ventricular septum and those with criss-cross atrioventricular connections may be the result of different degrees of rotation of the ventricular muscle mass. This rotation is not likely to be postseptational but preseptational. (b) Only those hearts with a complete 180 degrees rotation should be called criss-cross hearts. (c) Partial rotation results in a horizontal septum such that the right ventricle is invariably superior, regardless of atrioventricular concordance or discordance, situs solitus or inversus, or dextroversion. (d) Physiologic surgical correction is often possible but has to be tailored to the details of each heart.

Aorta↗
PubMed1987

The future of homografts.

The cryopreserved aortic valve is at least as satisfactory for aortic valve replacement as any known device. The future lies in fine-tuning the preservation process and sterilization. Concerning the use of allograft aortic valves as conduits, the allograft valved ascending aorta is the best conduit for the connection of right ventricle (or left ventricle) to pulmonary arteries. Availability, tailoring to size, and addition or need for composite parts remain to be developed. The allograft aorta and aortic valve may have great usefulness for replacing the aortic valve and ascending aorta in cases of aneurysms, infections, and congenitally narrowed left ventricular outflow tract; their use in these cases is yet to be increased. The future of allograft saphenous vein will involve in-vitro studies on cryopreservation toxicity, antibiotic toxicity, biochemical function of endothelial cells, and endothelial viability. Considerable in-vitro testing is necessary in both animal and human preparations. Also considered is the future of allograft small-caliber arteries--i.e., will they behave in a similar fashion to the intact internal mammary artery?--and the heart and peripheral vascular systems--i.e., are there any more spare parts?

Aortic Valve↗
PubMed1987

Role of surgery in infective endocarditis.

The thrust of the surgical literature at present and over the past 10 years has emphasized that early operation based on hemodynamic considerations and to some extent on the infecting organism offer a very reasonable outlook to the patient for hospital survival and long-term survival. However, as in all valvular heart disease, consideration of the risk of an indwelling prosthetic device and all its attendant complications must enter into decision making as to appropriateness and timing of operation.

Anti-Bacterial Agents↗
PubMed1987

A comparison of repair and replacement for mitral valve incompetence.

A total of 101 reparative and 389 valve replacement operations, isolated or combined with tricuspid annuloplasty or operations for coronary artery disease, were done for mitral incompetence (1975 to July 1, 1983). The patients undergoing repair as a group were younger and had less hemodynamic and functional derangement than those undergoing replacement. The prevalence of repair was less (p less than 0.001) for two surgeons than for the other four, even when possible differences in patient populations were taken into account by multivariate analysis. Five-year survival rate, including hospital deaths, was 76% after valve repair and 56% after valve replacement (p = 0.005). However, by multivariate analysis, valve replacement rather than repair was only possibly (p = 0.14) a risk factor. (Multivariate analysis in all patients undergoing mitral valve repair in the period 1967 to 1985 [n = 210] did not find the type of annuloplasty to be a risk factor.) The incidence of reoperation was no different after repair or replacement and there was no increase in the risk of reoperation late after repair. Endocarditis early or late after operation occurred in 11 of the 389 patients undergoing mitral replacement and in none of those undergoing repair (p = 0.08). The functional status of the patients was not different between the two groups. These data, and the experience of others, indicate the advantages of repairing rather than replacing the incompetent mitral valve whenever possible.

Adolescent↗
PubMed1987

Relief of life-threatening ventricular tachycardia and survival after direct operations.

Among 123 patients undergoing a direct operation, with or without other cardiac surgical procedures, for life-threatening ventricular tachycardia as a complication of ischemic heart disease, 68% of surviving patients were free of the return of ventricular tachycardia or sudden death 2 years after operation and 55% were free of these events at 5 years. The instantaneous risk (hazard function) of these events was highest immediately after operation and declined rapidly, so that by 3 months after operation instantaneous risk had merged with the constant-hazard phase which persisted as long as the patients were followed. More advanced impairment of left ventricular structure and function (with the exception of left ventricular aneurysm) increased the risk of occurrence of these events. Among patients with a negative electrophysiologic study (EPS) at hospital discharge, freedom from recurrent ventricular tachycardia or sudden death was 85% at 3 years. Survival, taking into account hospital deaths, was 54% 2 years after operation and 33% at 5 years. Most commonly (65% of instances) death was a result of acute, subacute, or chronic heart failure. The use of the technique of encircling endocardial myotomy increased the risk of death. Survival was particularly poor after the return of ventricular tachycardia. Direct operations for ventricular tachycardia are most likely to succeed in the presence of a discrete left ventricular aneurysm. The results are particularly unfavorable when there is severe global left ventricular dysfunction and no aneurysm. Improved myocardial protection during operation, and more specifically EPS-guided operations, may reduce the early risk of death and of return of ventricular tachycardia. The late return of ventricular tachycardia may be more related to a progressive secondary left ventricular cardiomyopathy than to an inadequate operation.

Adult↗
PubMed1986

Preservation of myocardial high-energy phosphates with vagal stimulation and hypothermic cardioplegia.

We examined three methods of inducing hypothermic cardioplegic arrest and related each to preservation of high-energy phosphates. Levels of adenosine triphosphate (ATP) and creatine phosphate (CP) in baseline rat hearts were compared with levels found after vagal stimulation combined with cardioplegia containing 15 mEq of potassium chloride (KCl) per liter, cardioplegia with 15 mEq of KCl per liter alone, and cardioplegia with 30 mEq of KCl per liter alone. Vagal stimulation produced complete electromechanical arrest in a shorter time than either 15 or 30 mEq of KCl alone (p less than 0.001 for both cardioplegic solutions compared with vagal stimulation), with fewer ventricular beats after ischemia than cardioplegic solution containing 15 or 30 mEq of KCl (p less than 0.001 and less than 0.01, respectively). Levels of ATP and CP, although less than baseline levels (p less than 0.01 and less than 0.001, respectively), were greater with vagal stimulation than with either 15 or 30 mEq of KCl (p less than 0.001 and less than 0.05, respectively, for ATP and p less than 0.001 for both CP levels). Furthermore, when all groups were combined, ATP and CP levels were found to correlate negatively with arrest time (r = -0.851 and -0.788, respectively; both r values significant at p less than 0.01) and with the number of ventricular beats after ischemia (r = -0.927 and -0.851, respectively; both r values significant at p less than 0.01). We conclude that electromechanical work quantified as time to arrest after aortic cross-clamping and as number of ventricular beats after ischemia correlates negatively with ATP and CP levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1986

Alprazolam treatment of postcoronary bypass anxiety and depression.

The effectiveness of alprazolam in treating symptoms of anxiety and depression in 60 patients undergoing coronary bypass surgery was assessed in a double-blind, placebo-controlled study. The results indicate that alprazolam treatment for anxiety following coronary bypass surgery, particularly symptoms occurring in the immediate postoperative period, can significantly affect patient outcome. Specifically, only modest but statistically significant improvement was observed in the alprazolam-treated groups at 1-month follow-up; however, alprazolam-treated patients were significantly more likely to experience a very rapid anxiolytic effect by postoperative day 8. The implications of this study are discussed with respect to patient management and models for future studies of anxiety in postoperative patient populations.

Adult↗
PubMed1985

Heart transplantation.

Modern concepts of cardiac transplantation are reviewed. Selection of potential recipients and donors is discussed with particular attention to those aspects of procurement that involve coordination with other transplant teams. Technical aspects of the operation, postoperative management, immunologic regimens, and late results, including physiologic testing and complications, are also reviewed.

Animals↗
PubMed1985

Intermediate-term results of coronary artery bypass grafting for acute myocardial infarction.

To assess the intermediate-term results of emergency coronary revascularization for acute myocardial infarction, we analyzed all patients (n = 35) who underwent coronary artery bypass grafting within 48 hr of acute myocardial infarction between January 1, 1982, and March 1, 1983. All patients had complete revascularization of infarct and noninfarct areas (3.4 +/- 1.65 distal anastomoses per patient). All patients have been traced as of February 21, 1984. Median duration of follow-up was 17.4 months (range 11.2 to 23.7). One in-hospital death (2.9%, 70% confidence limits 0% to 9%) occurred with low cardiac output, and no deaths occurred in the four patients who were in cardiogenic shock before surgery. One late death occurred from cancer, and 1 year overall actuarial survival is 94%. One patient underwent successful cardiac transplantation 8 months after operation. Ninety-seven percent of surviving patients are in NYHA class I or II, and 82% (27/33) have had no postoperative angina; six patients have mild angina. No patient has suffered a subsequent myocardial infarction. The early and intermediate results support continued application of emergency revascularization in higher-risk subsets of patients with acute myocardial infarction.

Adult↗
PubMed1984

Elevated catecholamines during cardiac surgery: consequences of reperfusion of the postarrested heart.

This study determines whether reperfusion of the heart with elevated blood levels of epinephrine (E) and norepinephrine (NE) during cardiac surgery produces deleterious effects. The study was conducted in 60 patients undergoing coronary artery bypass surgery. Arterial catecholamine values increased significantly (p less than 0.05), from prebypass control levels of 152 +/- 29 and 327 +/- 30 pg/ml of E and NE, respectively, to 415 +/- 78 and 554 +/- 49 pg/ml, at initiation of perfusion of the heart after the aortic cross-clamp was removed. Serial measurement of arterial (A) and coronary sinus (CS) E, NE, potassium, lactate, PO2 and CK-MB revealed that during 10 minutes of reperfusion the heart extracted E (positive A-CS difference, p less than 0.05), but that the NE A-CS difference was 0. The CS effluent contained significantly (p less than 0.05) higher concentrations of potassium, lactate and CK-MB during reperfusion than before aortic occlusion. There was no significant correlation of arterial E and NE, CS E and NE or A-CS differences in E and NE with myocardial release of lactate, potassium or CK-MB. There was a weak association (r = 0.4, p less than 0.01) between coronary sinus CK-MB and aortic occlusion time. Maximal arterial E and NE values did not correlate with 10-hour postoperative (maximal) CK-MB values. These results indicate that reperfusion of the postarrested ischemic heart with high levels of endogenously released catecholamines does not worsen ischemia or contribute significantly to myocardial damage.

Cardiopulmonary Bypass↗
PubMed1984

Adult human valve dimensions and their surgical significance.

After cardiac valve replacement, some patients may show little improvement in functional status, in part because their prosthesis is restrictive. Guidelines were sought for valve replacement from measurements of valve circumference and calculated circularized orifice area in 160 postmortem hearts from adults with and without congestive cardiac failure. Multivariate analysis was used to relate valve area to age, sex, height, body surface area and cardiac failure. Only sex and cardiac failure were significantly related to valve area. Body surface area and other variables were poorly related to valve area. The mean (+/- standard deviation) circularized orifice area for adult male (M) and female (F) heart valves in the absence of cardiac failure were: Aortic, M 4.81 +/- 1.30, F 3.73 +/- 0.98; pulmonary, M 4.88 +/- 1.25, F 4.32 +/- 1.03; mitral, M 8.70 +/- 2.08, F 6.94 +/- 1.41; and tricuspid, M 11.9 +/- 2.72, F 9.33 +/- 2.02. In cardiac failure, atrioventricular valves enlarge (p less than 0.004). Guided by these dimensions, the surgeon can aim to insert a prosthesis of appropriate size. Comparison of these sizes with the manufacturer's calculated area for current prostheses shows that most mechanical valves and bioprostheses are potentially restrictive at rest. Improved prosthestic design, valve repair whenever possible, and anular enlargement procedures would be required to eliminate this size disparity.

Adolescent↗
PubMed1984

Results of radionuclide assessment of cardiac function following transplantation of the heart.

Radionuclide assessment of ejection fraction was determined early and late postoperatively following cardiac transplantation in 16 patients. In 11 patients, ejection fraction was determined within 48 hours of an endocardial biopsy. There was no relationship between the severity of histologically evident rejection and the ejection fraction (Pearson correlation coefficient [r] = -0.11; p = 0.47). In 2 patients, severe graft fibrosis developed with consequent diminution in ejection fraction. There was no relationship between severity and duration of rejection or the amount of immunosuppression required to treat acute rejection and the development of graft fibrosis. The mean resting ejection fraction in 7 patients in follow-up ranging from 6 to 21 months after transplantation was 0.59 +/- 0.06 (standard deviation), and the mean exercise ejection fraction in 6 of these patients was 0.72 +/- 0.08. Radionuclide-determined ejection fraction is not predictive of rejection early after operation. During short-term late follow-up, systolic left ventricular function at rest and exercise has been retained at normal levels.

Heart↗
PubMed1984

Factors and their influence on regional cerebral blood flow during nonpulsatile cardiopulmonary bypass.

In this study we examined the relationship of regional cerebral blood flow (CBF) to mean arterial pressure, systemic blood flow, partial pressure of arterial carbon dioxide (PaCO2), nasopharyngeal temperature, and hemoglobin during hypothermic nonpulsatile cardiopulmonary bypass (CPB). Regional CBF was determined by clearance of xenon 133 in 67 patients undergoing coronary bypass grafting procedures. There was a significant decrease in regional CBF (55% decrease) during CPB, with nasopharyngeal temperature and PaCO2 being the only two significant factors (p less than 0.05). In a subgroup of 10 patients, variation of pump flow between 1.0 and 2.0 L/min/m2 did not significantly affect regional CBF. We conclude that cerebral autoregulation is retained during hypothermic CPB. Under the usual conditions of CPB, variations in flow and pressure are not associated with important physiological or detrimental clinical affects.

Adult↗
PubMed1984

A randomized comparison of crystalloid and blood-containing cardioplegic solutions in 60 patients.

To determine whether adding blood to a cardioplegic solution affects myocardial preservation, a randomized prospective study was carried out in 60 patients undergoing coronary revascularization to compare the effects of crystalloid potassium cardioplegics (group C) and potassium cardioplegic solutions to which blood has been added (group B) on markers of myocardial metabolism (lactate, inorganic phosphate, base deficit release, glucose and lactate uptake, oxygen extraction), myocardial damage (creatine kinase [CK]-MB levels), and cardiac performance (cardiac index and left atrial pressure). The solution with added blood had a significantly (p less than .05) greater oxygen content, a lower pH, and higher concentrations of potassium, calcium, sodium, and glucose. In group B patients there was a suggestion (p less than .06) of greater uptake of oxygen during the beginning of the initial cardioplegic infusion. During reperfusion there was no evidence of differential release of the metabolites of anaerobiosis and myocardial oxygen extraction and glucose and lactate uptake were similarly depressed in both groups. Likewise, CK-MB release after bypass was the same in both groups. Prompt, adequate functional recovery of cardiac index and left atrial pressure was observed in both groups. It was concluded that although there may be more oxygen available from the blood-containing solution during early infusion, there is no evidence that under the conditions of this investigation adding blood to cardioplegic solution improves myocardial preservation.

Blood↗
PubMed1984

Evolution and resolution of intracranial bacterial (mycotic) aneurysms.

Surgical therapy of bacterial intracranial aneurysms may prove difficult when multiple aneurysms are present or lesions are proximally located. Two patients underwent operation for bacterial intracranial aneurysms without resolution of their problems, in one case because of the involvement of a proximal branch of a dominant middle cerebral artery and in the other because of the presence of multiple bilateral aneurysms. Both patients underwent multiple angiographic evaluations during the course of treatment with documentation of complete resolution of their aneurysms over many months. The time course of the evolution and resolution of the bacterial intracranial aneurysms identified in the two patients is described, and antibiotic therapy and cardiac surgery are discussed.

Adolescent↗