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Biomedical subjects

G F Tyers

Publications and source records attributed to G F Tyers.

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

Balloon embolization of latrogenic aortocoronary arteriovenous fistula.

A detachable latex balloon was used to occlude an iatrogenic aortocoronary arterio-venous fistula. The aim of providing retrograde myocardial perfusion was not achieved to any significant degree because of rapid recruitment of collateral venous routes to the coronary sinus. This may have implications for the effectiveness of deliberate grafting of the coronary venous system with proximal venous ligation, as has been recommended when the coronary arterial system is small and diffusely diseased.

Angioplasty, Balloon, Coronary↗
PubMed1990

Current status of sensor-modulated rate-adaptive cardiac pacing.

In one third of patients requiring permanent cardiac pacing, sinoatrial response to exercise is inadequate. This has led to the development of a number of nonatrial sensors capable of increasing stimulation rate in response to metabolic demand. Initial sensor-modulated pacemakers were designed for use in the ventricle. This review was undertaken to compare ventricular rate-adaptive pacing with dual chamber and nonrate-adaptive atrial modes. Rate-adaptive ventricular pacing is primarily indicated in patients with complete heart block and nonfunctional atria in whom increased rates are not associated with the development of myocardial ischemia or retrograde conduction. A responsive atrium remains the best measure of metabolic demand, and devices capable of maintaining atrioventricular (AV) sequencing provide superior hemodynamic performance at usual activity levels. In addition, preserved AV relations reduce the incidence of new atrial fibrillation and stroke. Newer devices combining the advantages of atrial and nonatrial rate modulation with the preservation of AV synchrony will best utilize the developing sensor technologies.

Animals↗
PubMed1990

The Carpentier-Edwards standard porcine bioprosthesis. A first-generation tissue valve with excellent long-term clinical performance.

The Carpentier-Edwards standard porcine bioprosthesis was implanted in 1190 patients (1201 operations, 1303 valves) between January 1975 and June 1986; most implants were before 1982. The mean age of the patients was 57.2 years (range 8 to 85 years). The early mortality was 7.6% (aortic valve replacement 5.1%, mitral valve replacement 8.8%, and multiple valve replacement 15.3%). Late mortality was 3.9% per patient-year (aortic valve replacement 3.6%, mitral valve replacement 4.2%, and multiple valve replacement 3.8%). The total cumulative follow-up period was 6737 years. Thromboembolism was 1.5% per patient-year (fatal 0.4% per patient-year) (minor 0.6%, major 0.9%); antithromboembolic therapy-related hemorrhage was 0.5% (fatal 0.1%); prosthetic valve endocarditis was 0.6% (fatal 0.2%); nonstructural dysfunction was 0.5% (fatal 0.2%); and structural valve deterioration and/or primary tissue failure was 1.5% per patient-year (fatal, 0.2% per patient-year). Thromboembolism and structural valve deterioration were the significant complications, structural valve deterioration occurring primarily between the sixth and 10th year of evaluation. The overall patient survival was 65.0% for aortic valve replacement and 54.8% for mitral valve replacement (p less than 0.05) at 10 years. The patients were classified as 92.9% New York Heart Association functional classes III and IV preoperatively and 92.3% classes I and II postoperatively. Freedom at 10 years from thromboembolism was 84.3% for aortic valve replacement and 76.5% for mitral valve replacement (p = 0.05); structural valve deterioration was 78.6% for aortic valve replacement and 71.6% for mitral valve replacement (p less than 0.05); reoperation was 74.4% for aortic valve replacement and 67.1% for mitral valve replacement (p less than 0.05). Freedom from all valve-related complications at 10 years was 58.9% for aortic valve replacement and 46.8% for mitral valve replacement (p less than 0.05); valve-related mortality was 89.5% for aortic valve replacement and 82.6% for mitral valve replacement (p = not significant); mortality and reoperation was 58.9% for aortic valve replacement and 46.8% for mitral valve replacement (p less than 0.05); mortality and residual morbidity (treatment failure) was 87.2% for aortic valve replacement and 75.1% for mitral valve replacement (p = not significant); mortality, residual morbidity, and reoperation were 66.3% for aortic valve replacement and 54.9% for mitral valve replacement (p less than 0.05). The standard Carpentier-Edwards porcine bioprosthesis has provided satisfactory clinical performance and has afforded patients excellent quality of life.

Adolescent↗
PubMed1989

FDA recalls: how do pacemaker manufacturers compare?

To evaluate an apparent perception that there is no difference in reliability among the products of the major cardiac pacing system manufacturers, an extensive review of US Food and Drug Administration regulatory actions was performed. The study period was July 1974 through June 1987. The total number of affected devices was collected for each manufacturer. Available sales data were used to calculate their percentage of recalled products during two time periods. The percentage of potentially high-risk devices (Food and Drug Administration class I and II recalls) was high for one company, moderate for one, and relatively low for the rest. Potential biases in some other sources of reliability information, as well as implications for regulatory policies, are discussed. The data reported establish that there have been past deficiencies in recall management. Although further pacing device recalls are probable, appropriate early regulatory and manufacturer action should help to assure that both the immense cost and patient distress caused by pacer and related product problems in the past can be minimized in the future.

Equipment Failure↗
PubMed1989

Atrial pacing: efficacy and safety.

Atrial pacing has the advantages of simplicity, maintenance of AV synchrony, and economy. The major detraction has been the potential for deterioration of atrioventricular conduction. In this study, we followed 43 patients with sick sinus syndrome treated with atrial (AAI) pacing. Excellent initial implant parameters were obtained in all. Three early lead repositionings were required. Minor sensing and pacing problems could all otherwise be handled by reprogramming. Follow-up for a mean of 25 +/- 20 months demonstrated excellent performance of the pacing systems. Pacing and sensing thresholds and lead impedance indicated excellent lead performance. There were no late lead failures. Nine patients have had mild deterioration in atrioventricular conduction and one of these had a change to DDD pacing at the time of elective battery change. All patients are asymptomatic. Thus, chronic atrial pacing in selected patients is safe and reliable with good chronic lead performance and low risk of subsequent conduction system disease.

Adolescent↗
PubMed1988

Aortic dissection. A six year experience with 117 patients.

Acute aortic dissection is a medical emergency that demands immediate recognition and early precise angiographic diagnosis. One hundred seventeen patients were found to have aortic dissection between 1980 and 1986. Clinical presentation is of importance since hypertension favors the presence of type B dissection, whereas normotension or hypotension is usually indicative of a type A lesion. Supportive treatment should allow stabilization for diagnosis by angiography or computerized tomography in order to proceed with early surgical repair of all type A dissections. Management of the acute type B patient should initially be medical, but immediate surgical treatment should be carried out if there is failure to control the hypertension, continued pain, expansion or rupture of the aneurysm (including appearance of a pleural collection), development of a neurologic deficit, or evidence of compromise of a major infradiaphragmatic aortic branch. Any delay in surgical treatment once an indicative complication is identified will have an early adverse effect on prognosis. By applying these guidelines, an overall 65 to 75 percent hospital survival rate should be achieved.

Acute Disease↗
PubMed1988

Surgical management of spontaneous pneumothorax in patients with acquired immunodeficiency syndrome.

Spontaneous pneumothorax has been reported with increasing frequency in patients with acquired immunodeficiency syndrome and Pneumocystis carinii pneumonia. In the past year, we treated 4 patients with spontaneous pneumothorax. All of them were treated with closed tube thoracostomy, and 1 patient with bilateral apical cysts eventually required bilateral thoracotomies and pleurectomies. Only 1 patient had an uncomplicated hospital course. The remaining patients had prolonged air leaks, and 2 had synchronous pneumothoraces. Pneumothorax appears to be associated with P. carinii pneumonia. We recommend closed tube thoracostomy as the initial treatment in symptomatic patients. Pleurectomy for air leaks persisting longer than seven days can be safely performed in patients fit for thoractomy.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Carpentier-Edwards standard porcine bioprosthesis: primary tissue failure (structural valve deterioration) by age groups.

Primary tissue failure (structural valve deterioration) has been documented as the most prominent complication of porcine bioprostheses. The influence of age on primary tissue failure has received limited consideration. From 1975 to 1986, 1,301 Carpentier-Edwards standard porcine bioprostheses were implanted in 1,183 patients in 1,201 operations. Of the total number of prostheses, 97.7% were implanted prior to 1983. The mean follow-up was 5.6 years and was 97.5% complete. Primary tissue failure was identified in 96 patients (98 operations) at reoperation (95) or autopsy (3). One hundred four (104) prostheses were involved. Thirty-one failed after aortic valve replacement (AVR), 49 after mitral valve replacement (MVR), and 24 after multiple-valve replacement (18 patients). There were 47 male and 49 female patients. The mean age at implantation was 47 years (range, 8 to 72 years). The mean implantation time was 74.0 months. The freedom from primary tissue failure at 10 years is 77.0 +/- 2.9% overall; for AVR, 83.1 +/- 3.7%; for MVR, 72.1 +/- 4.9%; and for multiple-valve replacement, 65.5 +/- 7.8%. The freedom from deterioration for patients less than 20 years of age is significantly less than that for other age groups. The freedom from deterioration increased by decades; the greatest freedom was noted in patients 70 to 80 years old and 80 years old or older. The freedom from deterioration at 10 years for patients less than 30 years of age is 26.8 +/- 17.2%; 30 to 59 years, 77.4 +/- 3.0%; and 60 years and older, 83.1 +/- 4.2%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

The Carpentier-Edwards standard porcine bioprosthesis: long-term evaluation of the high pressure glutaraldehyde fixed prosthesis.

The Carpentier-Edwards standard porcine bioprosthesis was implanted in 1,000 operations (988 patients with 1,092 valves) between 1975 and 1981. The mean age of the patients was 56.8 years (range 8 to 85 years). During the years 1975 and 1981, approximately 97% of the total valvular surgery population received the prosthesis. The early mortality was 7.8% (including patients with concomitant procedures including coronary artery bypass and ascending aortic aneurysm resection). Late mortality was 3.8% per patient-year. The total cumulative follow-up was 5,937 years. Thromboembolism (TE) was 1.3% per patient-year (fatal 0.4%/patient-year) (minor 0.4%; major 0.9%); antithromboembolic therapy-related hemorrhage (ATH) 0.5% (fatal 0.1%); prosthetic valve endocarditis (PVE) 0.5% (fatal 0.2%); periprosthetic leak (PPL) 0.4% (fatal 0.2%); clinical valve dysfunction (CVD) 0.2% (fatal 0.02%); and structural valve deterioration (SVD)/primary tissue failure 1.6% per patient-year (fatal 0.2%/pt-yr). Thromboembolism and SVD occurring primarily between the sixth and tenth year of evaluation, were the significant complications. The overall patient survival was 60.5% +/- 2.4% at 10 years. The patients were classified as 93.5% NYHA functional Class III and IV, preoperatively and 93.1% Class I and II, postoperatively. The freedom at 10 years from TE was 82.9% +/- 2.7%; SVD 76.9% +/- 2.9%; and reoperation 70.8% +/- 3.1%. Freedom from all valve-related complications at 10 years was 54.3% +/- 3.1%; valve-related mortality 86.4% +/- 2.3%; mortality and reoperation (valve failure) 64.0% +/- 3.2%; mortality and residual morbidity (treatment failure) 82.3% +/- 2.6%; and mortality, residual morbidity, and reoperation (valve failure and dysfunction) 60.6% +/- 3.2%. There were 61 valve-related deaths of a total 352 deaths (early 7, late 54) (TE 21; ATH 7; CVD 1; PVE 12; PPL 9; and SVD 11). Valve-related reoperations were performed in 128 patients (TE 3; CVD 4; PVE 14; PPL 17; and SVD 90). The standard Carpentier-Edwards porcine bioprosthesis has provided very satisfactory clinical performance and afforded patients excellent quality of life. Primary tissue failure is the significant long-term complication.

Adolescent↗
PubMed1988

The mitral medical pericardial bioprosthesis: new generation bovine pericardial prosthesis.

The Mitral Medical Mitroflow pericardial bioprosthesis was implanted in 99 operations (99 patients with 104 valves) between 1984 and 1987. The mean age of the patients was 62.8 years (range 28 to 94 years). The early mortality was 6.1% (including patients with concomitant procedures--coronary artery bypass and ascending aortic aneurysm resection). Late mortality was 2.3% per patient-year. The total cumulative follow-up was 172 years. Thromboembolism (TE) was 4.1% per patient-year (fatal 1.2% per patient-year) (minor 2.3%; major 1.8%); antithromboembolic therapy-related hemorrhage (ATH) 0.6% (fatal 0.6%); prosthetic valve endocarditis (PVE) 0.6% (fatal 0%); periprosthetic leak (PPL) 0.6% (fatal 0%); clinical valve dysfunction (CVD) 1.2% (fatal 0%); and structural valve deterioration/primary tissue failure (SVD) 1.2% per patient-year (fatal 0% per patient-year). Thromboembolism was the significant complication. SVD occurred in two patients during the third year of evaluation. The overall patient survival was 89.2 +/- 3.3% at four years. The patients were classified as 91.9% NYHA functional Class III and IV preoperatively and 97.7% Class I and II postoperatively. The freedom at four years from TE was 88.5% +/- 4.9%; SVD 92.5 +/- 5.1%; and reoperation 89.8% +/- 5.3%. Freedom from all valve-related complications at four years was 76.8% +/- 6.6%; valve-related mortality 97.2 +/- 2.0%; mortality and reoperation (valve failure) 87.3% +/- 5.5%; mortality and residual morbidity (treatment failure) 95.5% +/- 2.6%; and mortality, residual morbidity, and reoperation (valve failure and dysfunction) 85.6% +/- 5.7%. There were three valve-related deaths of a total of ten deaths (early 2; late 1) (TE 2; ATH 1; CVD 0; PVE 0; PPL 0; and SVD 0). Valve-related reoperation was performed in four patients (TE 0; CVD 0; PVE 1; PPL 1; and SVD 2). The Mitral Medical Mitroflow pericardial bioprosthesis has provided very satisfactory clinical performance and afforded patients excellent quality of life.

Adult↗
PubMed1988

The Carpentier-Edwards supraannular porcine bioprosthesis. A new generation tissue valve with excellent intermediate clinical performance.

The Carpentier-Edwards supraannular porcine bioprosthesis, an investigational valve, was implanted in 1167 patients (1174 operations, 1274 valves) between November 1981 and December 1985 (age range 13 to 85 years, mean 61 years). The early mortality rate was 7.2% (with concomitant procedures 10.9%, without 4.8%; with previous operation 10.5%, without 6.6%). The late mortality rate was 4.5% per patient-year (aortic valve replacement, 4.0%; mitral valve replacement, 4.8%; multiple valve replacement, 5.6%). Total cumulative follow-up was 2272.3 years. The prevalence of thromboembolism was 2.6% per patient-year (fatal 0.4% per patient-year, major 1.4%, minor 1.2%); hemorrhage related to antithromboembolic therapy, 0.7% (fatal 0.1%); prosthetic valve endocarditis, 0.4% (fatal 0.2%); periprosthetic leak, 0.4% (fatal 0%); structural valve deterioration (primary tissue failure/structural failure), 0.1% per patient-year; and clinical valve dysfunction, 0.4%. The reoperation rate was 0.8% per patient-year (thromboembolism, 0.1%; clinical valve dysfunction, 0.1%; prosthetic valve endocarditis, 0.1%; periprosthetic leak, 0.4%; structural valve deterioration, 0.1%). Thromboembolism occurred throughout the observation period but with decreasing frequency, hemorrhage throughout the period in no predictable fashion, prosthetic valve endocarditis within 2 years, periprosthetic leak within 2 years, and structural valve deterioration occurred during the fourth year of assessment. The overall survival rate was 79.8% +/- 1.7% (4 years). Freedom (at 4 years) from thromboembolism was 92.2% +/- 1.2%; from structural valve deterioration, 98.8% +/- 0.8%; and from reoperation, 95.8% +/- 1.3%. Freedom from all complications (4 years) was 85.9% +/- 1.7%; from complication mortality, 98.4% +/- 0.4%; and from valve failure (mortality and reoperation), 94.3% +/- 1.3%. This investigational Carpentier-Edwards supraannular porcine bioprosthetic valve has provided excellent clinical performance and remains our overall prosthesis of choice.

Aged↗