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Biomedical subjects

W S Ring

Publications and source records attributed to W S Ring.

At least 19 recordsLinked to original sources
PubMed2000

Congenital Heart Surgery Nomenclature and Database Project: aortic aneurysm, sinus of Valsalva aneurysm, and aortic dissection.

The extant nomenclature for aortic aneurysms, sinus of valsalva aneurysms, and aortic dissections is reviewed for the purpose of establishing a unified reporting system. The subject was debated and reviewed by members of the STS-Congenital Heart Surgery Database Committee and representatives from the European Association for Cardiothoracic Surgery. All efforts were made to include all relevant nomenclature categories using synonyms where appropriate. Classification was based on morphology, histology, anatomic location, etiology, and acuity. A comprehensive database set is presented that is based on a hierarchical scheme. Data are entered at various levels of complexity and detail that can be determined by the clinician. These data can lay the foundation for comprehensive risk stratification analyses. A minimum database set is also presented that will allow for data sharing that would lend itself to basic interpretation of trends. Outcome tables relating diagnoses, procedures, and various risk factors are presented.

Aortic Dissection↗
PubMed1999

The Society of Thoracic Surgeons National Congenital Heart Surgery Database Report: analysis of the first harvest (1994-1997).

This analysis summarizes the first report of the Society of Thoracic Surgeons National Congenital Heart Surgery Database Committee in association with Summit Medical Systems. Twenty-four centers joined the program at various dates of entry resulting in 18,894 enrolled patient records. This report compiled the relevant clinical features of 18 congenital heart categories over a 4-year period (1994-1997), which included 8,149 patient records. The data analyses are largely descriptive in character. Missing data points were described and not omitted in the analysis. Statistical analysis was not performed due to missing data points in some categories. Certain trends, however, could be identified and are discussed. The first Society of Thoracic Surgeons National Congenital Heart Surgery Database Report has succeeded in establishing a finite record that can be improved to establish universal national and international utility, risk stratification, and scholarly outcome analyses.

Adolescent↗
PubMed1998

Usefulness of surveillance endomyocardial biopsy after pediatric cardiac transplantation.

Endomyocardial biopsy remains the 'gold standard' for the diagnosis of acute rejection after cardiac transplantation, but few guidelines exist to determine the indications for its use in pediatric cardiac transplant recipients. To determine the usefulness of surveillance endomyocardial biopsy, 176 biopsies were reviewed from 12 patients, aged 0.5-16 (average 9.7) yr, maintained on cyclosporine, azathioprine and prednisone immunosuppression, and followed 2.8-45.5 (average 26.3) months after cardiac transplantation. Children old enough to cooperate (n = 6) underwent biopsy on nine occasions in the first 6 months after transplantation and quarterly thereafter. Children too young to cooperate (n = 6) underwent biopsy with general anesthesia on four occasions in the first 6 months after transplantation and every 6 months thereafter. Additional biopsies were performed as warranted by symptoms or noninvasive tests. A new episode of acute rejection was present in 13 biopsies (7%); continuing or resolving rejection in 19 others (11%). Remaining biopsies had no evidence of rejection (82 biopsies, 47%), had lymphocytic infiltrates insufficient for diagnosis (47 biopsies, 27%), were inadequate for diagnosis (14 biopsies, 8%), or were consistent with ischemia (1 biopsy, 0.5%). During the first 6 postoperative months, eight of 101 biopsies were positive for rejection, three occurring on routine surveillance biopsy. After 6 months, five of 75 biopsies showed a new episode of rejection, only one occurring on routine surveillance biopsy. Based on this data, it is concluded that: 1) episodes of rejection are relatively uncommon with triple drug immunosuppression; 2) surveillance biopsies in the first 6 months after cardiac transplantation may show unsuspected rejection; and 3) routine surveillance biopsies more than 6 months after cardiac transplantation are unlikely to show rejection in the absence of symptoms or other tests.

Adolescent↗
PubMed1997

Surgical management of ventricular tachycardia.

BACKGROUND: Ventricular tachyarrhythmias are the leading cause of death from coronary artery disease. A small percentage of these arrhythmias originate in chronically ischemic myocardium, rather than acutely ischemic myocardium, and can be refractory to medical management. Epicardial mapping and focal cryoablation of foci demonstrating early activation may provide definitive therapy when pharmacologic management fails. We report a series of 42 consecutive patients with refractory ventricular tachycardia (VT) who were treated with open epicardial mapping and focal cryoablation after pharmacologic management failed. METHODS: We retrospectively reviewed the records of patients who underwent surgical treatment of malignant VT. For patients not recently seen in the clinic, we conducted telephone interviews. At the time of operation, epicardial mapping was performed to locate foci of early electrical activation. These foci were then cryoablated, using 2-minute applications of liquid nitrogen-cooled probes. All patients underwent postoperative electrophysiologic studies to test for inducible VT. RESULTS: Of these 42 patients, 34 (81%) were male, 8 (19%) female. Average age was 62.9 +/- 10.6 years; ejection fraction, 0.20 (range, 0.04 to 0.50); and number of foci ablated, 2.1 +/- 1.1 (range, 1 to 6). At the time of cryoablation, all patients underwent additional procedures, including aneurysmectomy, coronary artery bypass, or valve replacement. The 30-day operative mortality was 9.5% (4 of 42). Of the 38 survivors, 36 (94.7%) were clinically free of VT; the remaining 2 had spontaneous or inducible VT. CONCLUSIONS: Open cryoablation of foci propagating VT appears to be safe and effective. It may be the most definitive treatment for malignant VT.

Aged↗
PubMed1996

Outcome of cardiac transplantation in children. Survival in a contemporary multi-institutional experience. Pediatric Heart Transplant Study.

BACKGROUND: Meaningful analysis of survival and risk factors for death in children who undergo heart transplantation is problematic because of the small number of heart transplantations performed at individual institutions. METHODS AND RESULTS: To more accurately examine survival and risk factors for death in children undergoing heart transplantation, we analyzed 191 patients between 1 and 18 years old who received transplants at 22 centers in the Pediatric Heart Transplant Study between January 1, 1993, and December 31, 1994. Cardiac diagnosis was congenital heart disease in 74 patients (39%), dilated cardiomyopathy in 73 (38%), and other in 44 (23%). Actuarial survival was 93% at 1 month, 82% at 1 year, and 81% at 2 years after transplantation. The major causes of death (n = 31) were rejection (29% of deaths), early graft failure (19%), infection (16%), sudden death (13%), and other causes (23%). By multivariate analysis, risk factors for death were assist devices (P = .02), nonidentical ABO blood types (P = .05), and younger age (P = .10). CONCLUSIONS: Contemporary survival for pediatric heart transplant recipients > or = 1 year old is comparable to survival after adult heart transplantation. Risk factors for death are the need for assist devices, nonidentical ABO blood types, and younger age. Rejection is the most common cause of death after pediatric heart transplantation.

Adolescent↗
PubMed1996

Successful surgical repair of aortic dissection presenting with complete heart block.

Acute dissection of the ascending aorta can present with complete heart block if the dissecting hematoma involves the interatrial septum near the atrioventricular node. We report a case of acute type A dissection presenting with complete heart block treated with emergency grafting of the ascending aorta, aortic valve replacement, and coronary artery bypass grafting. The patient survived, although complete heart block persisted requiring permanent pacemaker implantation.

Aortic Dissection↗
PubMed1994

Two-dimensional and Doppler echocardiography alone can adequately define preoperative anatomy and hemodynamic status before repair of complete atrioventricular septal defect in infants < 1 year old.

OBJECTIVES: We sought to assess the ability of two-dimensional and Doppler echocardiography alone, without cardiac catheterization, to evaluate infants < 1 year of age for complete open heart repair of complete balanced atrioventricular (AV) septal defect. BACKGROUND: Two-dimensional echocardiographic-Doppler examinations provide accurate anatomic detail in patients with AV septal defect. Lung biopsy data have shown that patients rarely develop significant inoperable pulmonary vascular disease before 7 months of age. Although calculated pulmonary arteriolar resistance is often elevated in young infants with this heart defect, this elevation rarely reflects significant pulmonary vascular changes in infants < 7 to 12 months of age. METHODS: We performed a retrospective review of 34 patients who underwent complete repair of AV septal defect at our institution between January 1, 1988 and September 1, 1992. Some patients had both catheterization and echocardiographic-Doppler studies (group I, n = 16); others had only echocardiographic-Doppler studies (group II, n = 18). RESULTS: The groups were comparable with regard to age at echocardiography and operation, days in the hospital, days with ventilatory and inotropic support and occurrence of postoperative pulmonary hypertension. One child (2.9%) died during the early postoperative period, and one child in each group (5.8%) died within the 1st year of life. Preoperative echocardiography allowed better detailing of anatomy, valve commitment and regurgitation than was possible with catheterization alone. Knowledge of preoperative pulmonary resistance did not alter the surgical decision or predict postoperative pulmonary hypertension. There was no apparent difference in mortality between the two groups (0 vs. 5.5%), but the small number of patients in each group provides for a very low power (beta = 0.04) calculation. This mortality rate is not different from that reported in recent studies. CONCLUSIONS: Patients with AV septal defect can safely undergo surgical correction of this defect on the basis of echocardiographic-Doppler data alone.

Echocardiography, Doppler↗
PubMed1994

Discrepancy between pre- and post-transplant diagnosis of end-stage dilated cardiomyopathy.

A pretransplant diagnosis was compared with the diagnosis made after macroscopic and microscopic examination of the explanted hearts in 112 cardiac transplant recipients. A coronary angiogram was recorded in 87.5% and endomyocardial biopsy was performed in 12.5% of patients within 1 year of the transplant. Echocardiograms were obtained in all patients. Before transplantation, 57.1% of patients were classified as having ischemic cardiomyopathy and 33.9% were classified as having idiopathic dilated cardiomyopathy (IDC). At explantation, severe coronary artery disease was found in all patients with a pretransplant diagnosis of ischemic cardiomyopathy, in 9 patients with a pretransplant diagnosis of IDC (6 of them had a "normal" pretransplant angiograms), and in 3 of the 4 patients with presumptive alcoholic cardiomyopathy. Left ventricular hypertrophy, undetected on echocardiography, was found at autopsy in 11 patients with presumed IDC, and acute myocarditis was found in 3 patients with a pretransplant diagnosis of IDC. A correct pretransplant diagnosis can lead to different management (e.g., bypass surgery rather than transplant), and may also portend different pre- and post-transplant prognoses. The results of this study suggest that an "in-depth" search for a cause should be conducted in all patients with heart failure, regardless of their clinical presentation. Our study also emphasizes the limitations of coronary angiography and echocardiography in patients with IDC and the need for improving current diagnostic techniques in these patients.

Biopsy↗
PubMed1994

Differential reflex control of forearm and calf resistance vessels by chemosensitive cardiac afferent activation.

The aim of this study was to determine whether chemosensitive ventricular afferent activation in humans evokes a diffuse pattern of reflex vasodilation involving the skeletal muscle circulation of all the extremities or a highly specified pattern of vasodilation that is limited to the rather small vascular bed of the forearm. In 10 patients with innervated ventricles and 7 patients with denervated ventricles resulting from heart transplantation, we performed simultaneous plethysmographic recordings of blood flow in the forearm and calf during chemosensitive ventricular afferent activation with intracoronary Renografin. In patients with innervated ventricles, intracoronary Renografin evoked directionally opposite vascular responses in the forearm and calf: forearm resistance decreased from 50 +/- 11 to 31 +/- 8 units, whereas calf resistance increased from 42 +/- 7 to 59 +/- 9 units (P < 0.05, calf vs. forearm). Forearm vasodilation was eliminated after heart transplantation, indicating that this is a reflex response caused by ventricular afferents. In contrast, calf vasoconstriction was well preserved despite ventricular deafferentation, indicating that this response is caused by mechanisms other than ventricular afferent activation, possibly the sinoaortic baroreceptors. Taken together, these findings document a remarkable degree of specificity in the effects of cardiac afferent activation on the reflex regulation of regional vasomotor tone in humans.

Adult↗
PubMed1994

Treatment of acute vascular rejection with immunoadsorption.

BACKGROUND: Acute vascular rejection (AVR) is characterized by vascular injury and systolic graft dysfunction and is often associated with elevated panel reactive antibodies (PRAs) to HLA antigens. Plasmapheresis has been shown to improve the otherwise poor prognosis of AVR, but its use is often complicated and limited by hypotension. METHODS AND RESULTS: In three cardiac transplant recipients with severe hemodynamic compromise during AVR, refractory to standard therapy, extracorporeal immunoadsorption was performed using a protein A column. Plasma was removed at 10 to 20 cm3/min, passed through the column, and reinfused. All three patients had negative pretransplant PRAs. PRA rose before or during AVR and became negative in all three patients following immunoadsorption. Time course and number of treatments required to decrease PRA to < 5% varied. Concomitant with a decrease in PRA, histological findings and ventricular function improved and normalized. Ejection fraction rose from 23 +/- 2 to 56 +/- 8% and shortening fraction from 14 +/- 7 to 36 +/- 7%, P < .05 (both). One patient died from infection 2 months after resolution of AVR; the other two patients are alive 25 and 31 months after AVR with normal left ventricular function and coronary arteries. In both, since initial immunoadsorption course, PRA has remained negative and no rejection has occurred. In two patients, a circulating donor-specific or donor-related anti-HLA class I antibody was identified and removed by protein A column. CONCLUSIONS: Our preliminary data suggest that (1) immunoadsorption is effective in removing circulating immunoglobulins and is well tolerated; (2) AVR is preceded by or associated with circulating antibodies against HLA class I antigens; (3) their removal is temporarily associated with recovery of graft function and normalization of biopsy; and (4) anti-HLA class I antibodies can mediate vascular injury if they appear in the post-transplant period.

Acute Disease↗
PubMed1994

Effects of cardioplegic arrest on left ventricular systolic and diastolic function of the intact neonatal heart.

The effects of cardiopulmonary bypass and cardioplegic arrest on left ventricular systolic and diastolic function were studied in 20 intact neonatal lambs instrumented with ultrasonic dimension transducers and micromanometers for collection of left ventricular pressure-dimension data. Group I lambs underwent 2 hours of hypothermic cardiopulmonary bypass (25 degrees C) alone; group II lambs underwent 2 hours of hypothermic cardiopulmonary bypass (25 degrees C) with 1 hour of multidose, cold, crystalloid cardioplegic arrest (St. Thomas' Hospital No. 2 solution). The control neonatal lamb left ventricle was found to be relatively stiff, with the limit of diastolic filling reached at physiologic left ventricular filling pressures, resulting in apparent descending limbs of left ventricular function. After cardiopulmonary bypass, identical results were obtained in groups I and II. A significant loss of left ventricular compliance limited left ventricular performance via two mechanisms. First, left ventricular preload was significantly decreased, with a concomitant diminution in left ventricular stroke work; afterload (pressure work) was maintained at the expense of volume work (flow), which declined significantly. Second, preload behaved as though fixed, resulting in a loss of impedance matching (afterload mismatch). Although contractility as assessed by the end-systolic pressure-dimension relationship was significantly increased (because of increased levels of circulating catecholamines), global systolic performance as quantified by the stroke work/end-diastolic length relationship remained unchanged, reflecting the afterload sensitivity of the latter parameter in the face of fixed preload. We conclude that cardiopulmonary bypass in the intact neonate results in a loss of compliance and impedance matching rather than a loss of contractility; however, the addition of 1 hour of cold, crystalloid cardioplegic arrest results in no dysfunction beyond that attributable to cardiopulmonary bypass alone.

Animals↗
PubMed1993

Combined thrombolytic therapy for prosthetic mitral valve thrombosis.

Prosthetic valve thrombosis is associated with high mortality. The treatment of choice remains operation. This is a case report of the successful combination therapy of tissue plasminogen activator and urokinase for an isolated thrombosed prosthetic mitral valve in a postpartum patient in whom operation was thought to carry an unacceptable risk. Combined thrombolytic therapy or therapy with a single agent with a long half-life and a prolonged infusion time is suggested as an emergent treatment option for prosthetic mitral valve thrombosis.

Adolescent↗
PubMed1993

Perioperative measurements of interleukin-6 and alpha-melanocyte-stimulating hormone in cardiac transplant patients.

Interleukin-6 (IL-6) and alpha-melanocyte-stimulating hormone (alpha MSH) are important modulators of the immunologic response to tissue injury and antigenic challenge. Serial changes in the plasma concentrations of these two peptides were measured in 12 patients undergoing heart transplantation. Tissue concentrations of IL-6 in atrial samples from both donor and recipient hearts were also compared. Plasma IL-6 concentration remained stable prior to cardiopulmonary bypass (CPB), initially decreased with the onset of CPB, and then increased significantly over control values at the end of CPB (180 +/- 40 v 53 +/- 60 pg/mL). Plasma IL-6 remained elevated for at least 60 minutes after CPB, and then it returned to control values by 24 hours postoperatively (67 +/- 9 pg/mL). Examination of IL-6 changes after CPB in 10 additional patients undergoing nontransplant cardiac surgery with CPB revealed a similar elevation in IL-6 at 60 minutes after CPB (290 +/- 76 pg/mL). However, IL-6 in the nontransplant group remained significantly elevated at 24 hours (138 +/- 42 pg/mL). These combined results suggest that CPB causes a marked increase in IL-6, and that implantation of a new heart in transplant patients does not augment this increase. The return of IL-6 to control values by 24 hours in the patients who have had transplants suggests that immunosuppression has an appreciable effect on IL-6 at this time. In contrast to IL-6, plasma alpha MSH never increased above control values.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Reducing neurological complications after cardiac transplantation: technical considerations.

As the survival rate for cardiac transplantation improves, attention focuses on morbid events that occur perioperatively. Neurological problems have been recognized after transplantation, and appear to have multiple etiologies including thromboembolism, hypoperfusion syndromes, cerebral hemorrhage, and drug toxicities. Since 1988, 113 consecutive adults with end-stage cardiomyopathy were transplanted using a surgical technique that emphasizes precise everting atrial and great vessel anastomoses, a modified order of anastomoses, continuous endocardial and topical cold irrigation, and careful de-airing of the heart. Although a significant fraction of the patients were at high risk for cerebral events, the incidence of early and late neurological complications were each under 2%. The rate of early graft dysfunction was low and no patient was found to develop intracardiac thrombus on intermediate-term follow-up. These technical modifications may contribute to improved neurological outcomes after transplantation.

Anastomosis, Surgical↗
PubMed1993

Sequence elements required for transcriptional activity of the human myoglobin promoter in intact myocardium.

To define sequence elements required for myoglobin gene transcription in the intact heart, we examined the expression of a reporter gene under the control of a 380-bp upstream segment (-373 to +7) from the human myoglobin gene in transgenic mouse embryos and after gene transfer into left ventricular myocardium of adult rats. This proximal upstream region was sufficient to direct expression of luciferase selectively in cardiac and skeletal muscle of mouse embryos and to recapitulate the pattern of expression of the endogenous mouse myoglobin gene. This same upstream region was transcriptionally active after injection of plasmid DNA into the left ventricular wall of adult rats. Point mutations within two evolutionarily conserved sequence elements--a cytosine-rich (CCAC-box) motif and an A+T-rich (A/T) motif--severely impaired transcription within the intact heart. Nuclear extracts from neonatal cardiomyocytes contain protein factors that bind to each of these elements in a sequence-specific manner. We conclude that combinatorial interactions between the cognate DNA binding factors that recognize these motifs are necessary for transcriptional activity of the myoglobin upstream region in cardiac muscle.

Animals↗
PubMed1993

Relative contributions of cardiopulmonary and sinoaortic baroreflexes in causing sympathetic activation in the human skeletal muscle circulation during orthostatic stress.

The aim of this study was to reexamine the hypothesis that cardiopulmonary baroreflexes are more important than sinoaortic baroreflexes in causing vasoconstriction in the skeletal muscle circulation during orthostatic stress. We recorded muscle sympathetic nerve activity (MSNA) with microelectrodes in the peroneal nerve (and forearm blood flow with venous occlusion plethysmography) in normal subjects (innervated ventricles) and in heart transplant recipients (denervated ventricles) during graded lower body negative pressure (LBNP) performed alone and in combination with intravenous infusion of phenylephrine, which was titrated to eliminate the orthostatically induced fall in blood pressure and thus the unloading of both carotid and aortic baroreceptors. The principal new findings are as follows: (1) The increases in both MSNA and forearm vascular resistance during multiple levels of LBNP were not attenuated by heart transplantation, which causes ventricular but not sinoaortic deafferentation. (2) In heart transplant recipients, a small increase in MSNA during mild LBNP was dependent on a decrease in arterial pressure, but in normal subjects, a similar increase in MSNA occurred in the absence of any detectable decrease in the aortic pressure stimulus to the sinoaortic baroreceptors. (3) In normal subjects, the large increase in MSNA during a high level of LBNP was dependent on a decrease in arterial pressure and could be dissociated from the decrease in central venous pressure. Taken together, the findings strongly suggest that sinoaortic baroreflexes are much more important and ventricular baroreflexes are much less important than previously thought in causing reflex sympathetic activation and vasoconstriction in the human skeletal muscle circulation during orthostatic stress.

Female↗