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Biomedical subjects

W D Spotnitz

Publications and source records attributed to W D Spotnitz.

At least 55 records · Page 3Linked to original sources
PubMed1995

Predicting survival after coronary revascularization for ischemic cardiomyopathy.

BACKGROUND: The success of coronary revascularization for ischemic cardiomyopathy (left ventricular ejection fraction of 0.25 or less) has been unpredictable. We and others have demonstrated that the hospital operative mortality rate for these operations has been surprisingly low, particularly if evidence of ischemia is present. We subsequently liberalized our selection criteria based on our hypothesis that coronary artery bypass grafting is safe in this subset of patients regardless of the status of their distal coronary vasculature. METHODS: To examine this hypothesis, we studied retrospectively our patients undergoing coronary artery bypass grafting from 1983 to 1993. Ninety-six patients with ejection fractions of 0.25 or lower underwent this operation, with 88 hospital survivors (mortality 8%). All of the patients had clinical symptoms of heart failure. The male to female ratio was 4.6:1. The average age was 63.1 +/- 0.9 years (mean +/- standard error of the mean). Patients were excluded if they had valvular heart disease other than mild to moderate mitral regurgitation, required resection of a ventricular aneurysm, or required an emergency operation for acute coronary occlusion. Possible predictors of death were examined retrospectively. The catheterization films were reviewed retrospectively by a cardiovascular surgeon who was blinded to patient outcome and was never involved in the clinical management of any of the patients. Vessel quality was described as good, fair, or poor. RESULTS: Increased age and poor vessel quality were the only significant predictors of poor outcome. Sex, presence or absence of angina, preoperative angina, preoperative ejection fraction, preoperative arrhythmia disorder, aortic cross-clamp time, and the number of bypass grafts had no significant effect on outcome in the perioperative period. CONCLUSION: These results demonstrate that poor vessel quality and older age are predictors of poor outcome in patients with low ejection fractions undergoing myocardial revascularization. We conclude that poor distal coronary vasculature is a contraindication to coronary artery bypass grafting in patients with an ejection fraction of 0.25 or less, even if angina is present.

Age Factors↗
PubMed1995

General surgical complications can be predicted after cardiopulmonary bypass.

OBJECTIVE: The authors review the general surgical complications of cardiopulmonary bypass, including newer procedures such as heart and lung transplantation, to identify patients at higher risk. SUMMARY BACKGROUND DATA: Although rare, the general surgical complications of cardiopulmonary bypass are associated with high mortality. The early identification of patients at increased risk for these complications may allow for earlier detection and treatment of these problems to reduce mortality. METHODS: A retrospective review was performed of 1831 patients undergoing cardiopulmonary bypass from 1991 to 1993. This was done to identify factors that significantly contributed to an increased risk of general surgical complications. RESULTS: Factors associated with an increased risk of general surgical complications included prolonged cardiopulmonary bypass (p < 0.005) and intensive care unit stay (p < 0.002), occurrence of arrhythmias (p < 0.001), use of inotropic agents (preoperatively or postoperatively p < 0.001), insertion of the intra-aortic balloon pump (preoperatively p < 0.005, postoperatively p < 0.001), use of steroids (p < 0.001), and prolonged ventilator support (p < 0.001). Multivariate analysis identified use of the intra-aortic balloon pump (p < 0.001) as the strongest predictor of the general surgical complications of cardiopulmonary bypass. A variety of factors not contributing significantly to an increased risk also were identified. CONCLUSIONS: Factors indicative of or contributing to periods of decreased end-organ perfusion appear to be significantly related to general surgical complications after cardiopulmonary bypass.

Aged↗
PubMed1995

New insights into the physiology of retrograde cardioplegia delivery.

Although retrograde cardioplegia (RC) is being increasingly used in clinical practice, its physiology is unclear. Because the microvascular architecture of the coronary venous system is different from that of the arterial system, we hypothesized that myocardial perfusion would be different during RC compared with anterograde cardioplegia (AC) delivery. To better understand these differences, three groups of dogs were studied during similar RC and AC flow rates. Radiolabeled microsphere-derived microvascular flow underestimated total cardioplegia flow by 66% during RC. For the same flows, the first-pass extraction fractions of 201Tl and 99mTc were significantly less during RC compared with AC despite adjusting for microsphere loss. Myocardial contrast echocardiography (MCE), however, provided an accurate estimation of AC and RC flow rates. In addition, the rate of myocardial cooling for most of the left ventricular myocardium was similar for AC and RC at the same flow rates, as long as the flow rates were brisk. It is concluded that microvascular and nutrient flows are significantly lower at the same flow rates during RC compared with AC due to loss of RC at different microvascular sites. Unlike microspheres and diffusible radioisotopes, MCE can provide a reliable measure of myocardial flow during RC delivery. Furthermore, myocardial cooling is similar in most of the myocardium during high-flow RC and AC, which suggests that the clinical benefits of RC are probably related to myocardial cooling and that substrate replenishment may be better achieved at the same flow rates and myocardial temperatures with AC rather than RC.

Air↗
PubMed1995

Mechanism of mitral leaflet excursion.

The factors that influence the extent of mitral leaflet opening (MLO) and closure (MLC) have not been defined. We hypothesized that left ventricular (LV) systolic function determines the rate of increase of the early diastolic left atrial (LA)-LV pressure gradient, which is responsible for the extent of MLO, and also the rate of change of the early systolic LV-LA pressure gradient, which determines the degree of MLC. Accordingly, global LV function was changed by altering left main coronary artery flow with LA pressure held relatively constant. LV end-systolic dimension and peak positive LV rate of pressure development (dP/dt) correlated best with the degrees of MLO and MLC, with average correlation coefficients of 0.88 and 0.68, and 0.86 and 0.72, respectively. Although transsecting the submitral apparatus resulted in flailing of the mitral leaflets during normal LV systolic function, the extents of MLO and MLC during LV systolic dysfunction were still influenced by LV systolic function. It is concluded that LV systolic function determines the extent (both opening and closure) of mitral leaflet excursion.

Animals↗
PubMed1995

Fibrin sealant in the United States: clinical use at the University of Virginia.

Fibrin sealant use in the United States has been limited because of the lack of a commercially available, government approved product. However, the significant need and usefulness of this material at the time of surgical operations has stimulated alternative sources of production. At the University of Virginia, the Blood Bank produces concentrated single donor or autologous fibrinogen for use with commercially available bovine thrombin in order to make fibrin sealant. The hemostatic and adhesive properties of fibrin sealant have been used since 1985 at this Center in a wide variety of operations with over 90% effectiveness. This chapter will review the development and role of this material in modern clinical surgery at this institution. The advantages, disadvantages, and never applications of this substance in various forms will be assessed. The role of fibrin sealant is increasing in this country and additional developmental work is continuing. The era of a commercially available product in the United States appears to be on the horizon.

Animals↗
PubMed1994

Successful use of undersized donors for orthotopic heart transplantation--with a caveat.

Accepted clinical practice has been to require body weights to be within 20% as a criterion for matching donor to recipient for cardiac transplantation. From November 1989 through September 1993 we began accepting larger differences in body weight between donor and recipient with 80 orthotopic heart transplants performed. Twenty-eight of these transplants used undersized donors (donor-to-recipient body weight ratio [DRBW] of 0.6 to 0.8) with the remaining donors being either size matched (DRBW = 0.8 to 1.0) or oversized (DRBW > 1.0). Thirty-three of the 80 transplant recipients (41%) were classified preoperatively as United Network for Organ Sharing (UNOS) status I and the remaining patients were classified as UNOS status II. Hospital survival for status I recipients was 9 of 14 (64%) for undersized donors, 7 of 8 (87.5%) for sized-matched donors, and 11 of 11 (100%) for oversized donors (p < 0.05). Hospital survival for status II recipients was 12 of 14 (85.7%) for undersized donors, 24 of 24 (100%) for sized-matched donors, and 8 of 9 (88.8%) for oversized donors. Our data support the continued use of hearts from undersized donors in status II recipients. The use of hearts from undersized donors in status I recipients is associated with increased mortality compared with size-matched donors and must be undertaken with caution.

Adult↗
PubMed1994

Removal of an infected right atrial mass in a patient with sickle cell disease.

The use of indwelling central catheters for hyperalimentation, chemotherapy, and long-term venous access is increasing. We report the successful removal of an infected right atrial mass associated with the use of a central catheter in an adult with sickle cell disease. The clinical options for the treatment of infected atrial thrombus as well as the challenge of performing cardiopulmonary bypass in patients with sickle cell disease are briefly discussed.

Adult↗
PubMed1993

Successful preoperative diagnosis and treatment of a saphenous vein coronary artery bypass graft aneurysm.

A 71-year-old man who underwent a coronary artery bypass using a saphenous vein bypass graft (SVG) in 1977 presented with a new mediastinal mass on chest radiography. A variety of imaging techniques were applied and magnetic resonance imaging (MRI) provided excellent anatomic detail of an aneurysm of the previously placed SVG. This condition was successfully treated with repeat operation, aneurysm resection, and placement of new bypass grafts. We recommend that any patient with a history of previous coronary artery grafting who presents with a mediastinal mass be evaluated for the possibility of a graft aneurysm. The best mediastinal imaging technique for this purpose appears to be an MRI scan.

Aged↗
PubMed1992

Successful treatment of postoperative chylothorax using an external pleuroperitoneal shunt.

We report 3 patients with chylothorax who were successfully managed as outpatients using external pleuroperitoneal shunts. This external shunt has the advantage over subcutaneously placed shunts of pumping large volumes of fluid with each compression of the pumping chamber, of not causing the discomfort associated with pumping a subcutaneous chamber, of not becoming difficult to find in the subcutaneous space, and of being constructed of larger components which do not kink or become easily clogged with fibrinous debris.

Adult↗
PubMed1992

Effects of antifibrinolytic agents on the life span of fibrin sealant.

Fibrin sealant, a biologic glue consisting of fibrinogen and thrombin, has been used in a variety of surgical procedures. The usefulness of fibrin sealant may be prolonged by the addition of antifibrinolytic agents. This study compared the efficacy of transexamic acid (30 mg/ml), epsilon-aminocaproic acid (25 mg/ml), and aprotinin (3000 KIU/ml) to provide data on the choice of an appropriate antifibrinolytic agent for use with fibrin sealant. By use of a modified in vitro plasma euglobulin lysis time (hours), all agents were found to be superior (n = 10 for each agent, P < 0.05, analysis of variance for completely randomized design followed by Dunnett's test for multiple comparisons) to control. Lysis times (mean +/- SE) were (control) 50.9 +/- 0.5, (tranexamic acid) 402.6 +/- 25.4, (epsilon-aminocaproic acid) 433.5 +/- 21.2, and (aprotinin) 393.9 +/- 26.0. Using the in vivo implantation of fibrin sealant supplemented with 125I-fibrinogen in the rat peritoneum significant improvement in percentage clot (mean +/- SE) remaining was found (P < 0.05, analysis for repeated measures followed by tests for multiple comparisons) under the following conditions: at 3 hr by weight (n = 15), tranexamic acid (70.13 +/- 2.02%) was superior to aprotinin (61.22 +/- 2.21%) and control (61.28 +/- 2.36%); at 3 hr by radioactivity counts (n = 19), tranexamic acid (76.29 +/- 0.75%) was superior to epsilon-aminocaproic acid (72.52 +/- 1.28%) and aprotinin (73.84 +/- 0.78%); at 72 hr by radioactivity counts (n = 10), aprotinin (27.30 +/- 2.45%) was superior to epsilon-aminocaproic acid 19.76 +/- 3.09% and control (20.38 +/- 3.01%). These data suggest the early (3-hr) superiority of tranexamic acid as an inhibitor of plasminogen activation and the late (72-hr) effectiveness of aprotinin as an inhibitor of plasmin. The possibility of a synergistic effect of tranexamic acid and aprotinin is suggested.

Adhesives↗
PubMed1992

Myocardial contrast echocardiography and the transmural distribution of flow: a critical appraisal during myocardial ischemia not associated with infarction.

OBJECTIVES: This study was undertaken to determine whether myocardial contrast echocardiography can be used to estimate the transmural distribution of flow. BACKGROUND: Myocardial contrast echocardiography has been shown to reliably measure average transmural blood flow during myocardial ischemia. However, there is controversy regarding its ability to determine the transmural distribution of flow. METHODS: The transmural distribution of flow was measured in 21 open chest anesthetized dogs with use of radiolabeled microspheres and sonicated albumin microbubbles (mean size 4.5 microns). In the 11 Group I dogs, myocardial contrast echocardiography was performed at baseline and during left anterior descending artery stenosis. In five of these dogs, it was also performed during left circumflex artery stenosis. In these dogs large (mean 12 microns) hand-agitated bubbles were also used. In the five Group II dogs, myocardial contrast echocardiography was performed before and 45 s after intracoronary injection of 6 mg of papaverine in the presence of a critical left circumflex artery stenosis. The five Group III dogs were studied during cardiopulmonary bypass at baseline and during left anterior descending artery stenosis. Off-line image analysis of the echocardiographic images was performed and time-intensity curves obtained from these images were correlated with radiolabeled microsphere-derived flows. RESULTS: The ratios of the parameters derived from the endocardium and epicardium during myocardial contrast echocardiography were found to correlate poorly (ranging from R2 = 0 to R2 = 0.35) with radiolabeled microsphere-derived endocardial/epicardial flow ratios over a wide range of flow ratios (0.01 to 2.58). These results were not influenced either by the location of the regions of interest (left anterior descending vs. left circumflex artery bed) or by the size of the bubbles (4.5 vs. 12 microns). CONCLUSIONS: Myocardial contrast echocardiography cannot be used to assess the transmural distribution of flow during myocardial ischemia not associated with infarction.

Animals↗
PubMed1992

A mathematical model for the quantification of mitral regurgitation. Experimental validation in the canine model using contrast echocardiography.

BACKGROUND: Because the clearance of contrast from the left atrium (LA) relative to the left ventricle (LV) depends on the degree of mitral regurgitation (MR), we hypothesized that a mathematical model can be developed that would provide a quantitative estimation of MR from the washout of contrast from these chambers. METHODS AND RESULTS: After mathematically developing the model, we performed experiments in two groups of dogs with the use of contrast echocardiography. Group 1 consisted of nine dogs in which different degrees of MR were produced by creating ischemic LV dysfunction. Contrast was injected into the LV, and MR was graded visually on a scale of from 0 to 4+. Videointensity plots generated from the LA and LV were provided to the model. There was excellent correlation between visual assessment of MR and model-derived regurgitant fraction in the 33 stages: y = 0.16x + 0.002 (r = 0.97, p less than 0.001, SEE = 0.06). To obtain a more quantitative validation, we placed electromagnetic flow probes on the aorta and just cephalad to the mitral annulus in six dogs (group 2) during cardiopulmonary bypass. Different degrees of MR were produced by chordal traction and/or myocardial ischemia. Regurgitant fraction was calculated at each stage from the flow probe and videointensity data. There was excellent correlation between flow probe and model-derived regurgitant fraction (y = 0.90x + 0.03; r = 0.96, p less than 0.001, SEE = 0.06), and close interobserver and intraobserver correlations were noted using flow probe and contrast echocardiographic data. CONCLUSIONS: A mathematical model that uses the clearance of contrast from the LA relative to the LV can be used to accurately measure the severity of MR. These findings may have important practical implications for the quantification of MR.

Animals↗
PubMed1992

On-line intraoperative quantitation of regional myocardial perfusion during coronary artery bypass graft operations with myocardial contrast two-dimensional echocardiography.

We hypothesized that the success of coronary artery bypass graft operations could be assessed by means of on-line quantitative myocardial contrast echocardiography. Accordingly, myocardial contrast echocardiography was performed at baseline and after each placement of venous graft in 21 patients undergoing coronary artery bypass graft operations. Time-intensity plots were generated on-line with the use of a dedicated computer system, and areas under the curve were assessed for each injection. Successful on-line quantitation of myocardial contrast echocardiography data was performed in 17 patients; this allowed comparison before and after coronary artery bypass graft operations for 21 grafts, with agreement between expert visual analysis and quantitative data in 91% of these cases. Three distinct perfusion patterns were noted on myocardial contrast echocardiography: (1) reduced contrast effect before coronary artery bypass graft operations with improvement after coronary artery bypass graft operations (n = 11); (2) adequate contrast effect before coronary artery bypass graft operations with no change after coronary artery bypass graft operations (n = 9) (for patients in group 2, the mean percentage of coronary stenosis was less than the mean for patients in group 1-67% +/- 25% vs. 88% +/- 20%, p = 0.05); and (3) no contrast effect either before or after coronary artery bypass graft operations in one patient with previous infarction. One third of the time (34 of 95 injections), on-line quantitation was unsuccessful. Failure was related three times more often to problems associated with myocardial contrast echocardiography, such as attenuation and inadequate quality of bubbles, than to computer failure. Despite its limitations, on-line quantitative myocardial contrast echocardiography is feasible in patients undergoing coronary artery bypass graft operations and provides important objective information regarding the success of revascularization.

Aged↗
PubMed1991

Mechanism of ischemic mitral regurgitation. An experimental evaluation.

BACKGROUND: Papillary muscle dysfunction (PMD) has been implicated in the pathogenesis of ischemic mitral regurgitation (MR). We hypothesized that ischemic MR is not caused by PMD and/or dysfunction of the myocardial regions from where the papillary muscles arise but is related to reduction in global left ventricular (LV) function. To test this hypothesis, three groups of dogs were studied. METHODS AND RESULTS: In group 1 dogs (n = 8), varying degrees of regional and global LV dysfunction were produced. In group 2 dogs (n = 7), the circulation to the papillary muscles was isolated from that of the rest of the LV. Dysfunction of one or both papillary muscles was produced without producing global LV dysfunction. Global LV dysfunction was also produced while keeping papillary muscle function intact. The degree of MR (assessed using contrast echocardiography) was correlated in both groups of dogs with thickening of the papillary muscles and regional and global LV function. In the group 3 dogs (n = 6), the spatial distribution of blood flow within each papillary muscle was determined during ischemia by using radiolabeled microspheres. Thickening of the papillary muscles was assessed at three different levels along their lengths and was correlated with average blood flow at these levels. In group 1 dogs, MR was noted only when global LV function was affected and its severity correlated inversely with global LV function (r = -0.84 with peak positive LV dP/dt and r = -0.95 with global LV thickening, respectively). In comparison, there was poor correlation between MR and anterior and posterior papillary muscle thickening (r = -0.38 and r = -0.49, respectively). In group 2 dogs, MR did not occur in the presence of either PMD or akinesia of the immediately adjacent LV myocardium. MR occurred only when global LV dysfunction was produced (with the papillary muscle function intact), and its severity correlated inversely with global LV function (r = -0.92 with LV dP/dt and r = -0.86 with global LV thickening, respectively). There was poor correlation between the degree of MR and thickening of the anterior and posterior papillary muscles (r = -0.24 and r = -0.38, respectively). In both groups of dogs, MR was associated with incomplete mitral leaflet closure (IMLC), and the severity of MR correlated linearly with the degree of IMLC (r = 0.98). MR was never associated with mitral valve prolapse. In the group 3 dogs, despite more inhomogeneous flow during ischemia to the anterior compared with the posterior papillary muscle, mean thickening of these muscles was similar (3 +/- 10% and 3 +/- 4%, respectively). Furthermore, there was minimal variability in thickening between different parts of the muscles (3 +/- 2% and 5 +/- 3%, respectively). CONCLUSIONS: It is concluded that PMD and/or dysfunction of the immediately adjacent LV myocardium does not result in MR. MR occurs during ischemia only when global LV function is affected, even when thickening of the papillary muscles and the immediately adjacent LV remains intact. MR in this situation is related to IMLC; the greater the degree of IMLC, the greater the MR. These findings suggest that the mechanism of ischemic MR is not related to PMD. There may also be important therapeutic implications of these findings.

Animals↗
PubMed1990

Seroma prevention using fibrin glue in a rat mastectomy model.

Seromas are a frequent complication of mastectomy (17% to 53%) in humans and are correlated to skin flap elevation, lymphovascular interruption, and drainage into surgically created potential spaces. The use of intraoperative topical fibrin glue to reduce morbidity in rats undergoing radical mastectomies has been evaluated. A model consistently producing seromas was developed by radical mastectomy and lymphadenectomy in the Sprague-Dawley rat. A fibrin glue application procedure was tested using this model. The double-blinded protocol called for spray application of saline or fibrin glue to mastectomy wounds followed by sequential inspection and necropsy on postoperative days 5, 8, 11, and 14. Topical fibrin glue was shown to be statistically significant in decreasing the presentation of seromas following a radical mastectomy in the Sprague-Dawley rat.

Animals↗