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Biomedical subjects

G L Grunkemeier

Publications and source records attributed to G L Grunkemeier.

106 records · Page 6Linked to original sources
PubMed1980

Year of operation as a risk factor in the late results of valve replacement.

The actuarial thromboembolic rates of aortic and mitral silicone ball valves used during the second decade of cardiac valve replacement are significantly lower than the rates for the same prostheses implanted during the first decade, as shown in the following table: (Formula: see text). The embolus-free rates are significantly different (p < 0.01) in both the mitral and aortic series. Five-year embolus-free rates for the composite-strut caged-ball, Björk-Shiley tilting disc, and porcine xenograft valves all fall in the range of from 81% to 92% for the mitral position and from 91% to 97% for the aortic. Thus the standard silicone ball-valve prosthesis, used during the current era, has a thromboembolic risk as low as that reported with other concurrently utilized valve substitutes. This striking reduction in thrombogenicity demonstrates that the time frame of implantation must be considered when evaluating the results of cardiac valve replacement.

Adolescent↗
PubMed1979

Twelve year results with a caged-ball mitral prosthesis.

Over a 12 year period in 230 patients mitral valve replacement was performed using the model 6120 Starr-Edwards prosthesis. Operative mortality was 6.5%, mean follow-up of the operative survivors was 3.9 years. Estimated late survival rate was 80% at 5 years and 73% at 12 years. 38% of late deaths were considered valve-related. Under routine anticoagulation thromboembolism occurred at a rate of 4.7% per patient-year with a fatal thromboembolic incidence of 1.4% per patient-year. In comparison with data available on other currently used prosthetic valves it appears that the rates of valve-related complications are quite similar, with the 6120 Starr-Edwards model being subject to the longest follow-up.

Belgium↗
PubMed1979

Critical pulmonary valve stenosis with intact ventricular septum.

This study presents our experience in the surgical management of the newborn with critical pulmonary stenosis and intact ventricular septum. During the last decade we have seen 11 such patients, with a mean age of 2.3 days (maximum 6 days) and a mean weight of 3.6 kilograms (maximum 4.5 kilograms). The primary operation was a valvotomy in 7 patients (one of whom also had a systemic-pulmonary shunt), a commissurotomy with cardiopulmonary bypass in 3 patients, and a shunt alone in 1 patient. One infant died on the second postoperative day and another died following reoperation at 4 months. The other 9 patients were all alive and progressing satisfactorily when last seen. Five of these patients were beyond their third postoperative year and the longest survivor was at 7.9 years. Four of the long-term survivors had undergone reoperation. Our choice of operation remains transventricular valvotomy, although an open procedure utilizing cardiopulmonary bypass presents an attractive alternative. A systemic-pulmonary shunt as an addition to either of these operations is unnecessary. The perioperative use of prostaglandin E brings about substantial improvement in the early results.

Age Factors↗
PubMed1978

Non--cloth-covered caged-ball prostheses. The second decade.

The Starr-Edwards Models 6120 mitral and 1200/60 aortic valves are caged-ball prostheses with cloth-covered sewing rings and bare-metal struts. Introduced in 1965, they have been in continuous clinical use longer than any other currently available heart valve prostheses. Late results with this valve are analyzed and compared with recent series employing other current valve prostheses. One hundred thirty-four mitral 6120 prostheses were inserted at the University of Oregon Health Sciences Center from 1965 through 1977, with 118 operative survivors followed for a mean of 5.4 years. Twelve-year survival rate (+/- standard error) was 50 (+/-8) percent. Twelve percent of late deaths were valve related. Eighty-eight (+/-5) percent of valves were still in place at 12 years. The embolic rate was 5.8 (+/-1.0) percent per patient-year for all emboli and 2.2(+/-0.6) percent per patient-year for serious emboli. Two hundred forty-nine operative survivors among 282 patients undergoing aortic valve replacement during the same period of time were followed for a mean of 4.3 years. Twelve-year survival was 61 (+/-6) percent and the removal-free rate was 92(+/-5) percent. Six percent of late deaths were valve related. Embolic rates were 5.0 (+/-.7) percent and 1.8 (+/-.4) percent per patient-year for all emboli and serius emboli, respectively. Structural failure, specifically ball variance, was not encountered with this prosthesis. Ninety percent of 10 year survivors are in N.Y.H.A. Functional Class I or II. There was one anticoagulant-related death in 1,698 patient-years of follow-up. The current non--cloth-covered caged-ball valves provide unquestionable durability and well-documented results into their second decade of use. They provide a base line for comparison with newer prostheses and offer a valid, current choice for both aortic and mitral valve replacement.

Aortic Valve↗
PubMed1977

Actuarial analysis of surgical results: rationale and method.

The use of time-related methods of statistical analysis is essential for valid evaluation of the long-term results of a surgical procedure. Accurate comparison of two procedures or two prosthetic devices is possible only when the length of follow-up is properly accounted for. The purpose of this report is to make the technical aspects of the acturial, or life table, method easily accessible to the surgeon, with emphasis on the motivation for and the rationale behind it. This topic is illustrated in terms of heart valve prostheses, a field that is rapidly developing. Both the authors and readers of articles must be aware that controversies surrounding the relative merits of various prosthetic designs or operative procedures can be settled only if proper time-related methods of analysis are utilized.

Follow-Up Studies↗
PubMed1977

Aortic valve replacement: a ten-year follow-up of non-cloth-covered vs cloth-covered caged-ball prostheses.

From 1965 to 1976, 721 isolated aortic valve replacements were performed at the University of Oregon hospitals, utilizing Starr-Edwards caged-ball prostheses. Three models of aortic prostheses were introduced during this period: a non-cloth-covered model has been in continuous use since 1965; a cloth-covered model was begun in 1968 and has been supplanted by the modified composite-strut or "track" model since 1972. The 5-year actuarial survival rate for operative survivors is about 80% for both non-cloth-covered and cloth-covered valves, while the 10-year survival is 61%, based on the older model only. The actuarially-determined percentages of patients experiencing significant thromboembolic episodes (i.e., all except transient ischemic episodes) at 5 years are 7% for the cloth-covered and 9% for the non-cloth-covered model. If transient ischemic attacks are included, the cloth-covered model has only an 8% incidence at 5 years compared to a 22% incidence for the older model. However, the cloth-covered valves are subject to a higher risk of reoperation because of the possibility of cloth injury. The "track" valve, therefore, was designed with exposed metal on the inner surface of each strut to prevent ball-cloth contact. In 107 patients (mean follow-up period 1 year) receiving anticoagulation, this prosthesis has maintained the same low incidence of thromboembolism as the previous cloth-covered model, with no reoperations for valve failure.

Aortic Valve↗
PubMed1976

Statistical analysis of pacemaker follow-up data. Rate stability and reliability.

In a rate-stable pacemaker, pacemaker rate reflects battery voltage level and should remain constant or be slightly depleted with time in a linear fashion until failure occurs. Linear regression techniques are therefore particularly suited to the analysis of pacemaker rate data. Data on model 8114/8114A Starr-Edwards pacemakers followed at the University of Oregon Health Sciences Center were studied. For a given pacemaker both the slope of the regression line and the standard deviation about the regression line are proportional to the original rate. Natural indices of rate depletion and rate stability for each pacemaker can therefore be calculated by dividing the slope and the standard deviation, respectively, by the inpercept of the corresponding regression line. This model pacemaker has a small average standard deviation so that significant variations from the line of regression, indicating impending pulse generator failure, can be detected in spite of random fluctuations. Emergency and prophylactic replacements can therefore be kept to a minimum so that pulse generator lifetime is maximized. Success in extending pulse generator longevity can be measured by actuarial techniques, which show this pacemaker to have a median battery depletion time of 38 months and a median replacement time of 35 months.

Adolescent↗
PubMed1976

A hermetically sealed mercury cell pacemaker: advantages and early clinical results.

Despite the known advantages of hermetic encapsulation of implanted pacemakers, only a few conventionally powered models are totally hermetically sealed, and most of them are not yet clinically available. This report describes the results with a mercury cell unit which has been in clinical use since 1970 and has been totally hermetically sealed since 1974. The lowered premature failure rate with the newer model substantiates the theoretical advantages of hermetic encapsulation. The rate behavior of the pulse generator, upon which our telephone follow-up system is based, is essentially the same for both models.

Heart Diseases↗
PubMed1975

An improved statistical method for assessing the results of operation.

The advantages of the acturarial method of analyzing postoperative survival are now widely accepted. In evaluating the late results of heart valve replacement operations, however, certain nonfatal complications must also be considered. The use of individual event-free rates does not portray individual risk, since some valves have multiple complications. By using cummulative complication-free rates, however, it is possible to estimate the percentage of valves active and free from certain major complications for each postoperative interval. A series of actuarial curves is used, each of which represents a different major complication. These curves are subtracted progressively from the total of valves at risk, and an acturial representation of complication-free survival results.

Heart Valve Prosthesis↗
PubMedDate not supplied

Ten-year survival following aortic valve replacement: A multivariate analysis of coronary bypass as a risk factor.

The additional risk of coronary bypass surgery was analysed in 664 patients over 40 years of age undergoing aortic valve replacement between 1969 and 1981. Four hundred sixty-seven patients underwent aortic valve replacement alone, while 197 patients with coronary artery disease underwent combined aortic valve replacement and coronary bypass surgery. There were no significant differences in the preoperative hemodynamic characteristics of the two groups of patients. There were 41 (9%) operative deaths following aortic valve replacement alone and 20 (10%) following aortic valve replacement with coronary bypass surgery. Since 1976, operative mortality has fallen to 5% and perioperative myocardial infarction to 2% following the combined procedure. Ten-year actuarial survival (standard error) was 56 (3%) following aortic valve replacement and 49 (6%) following aortic valve replacement and coronary bypass surgery. A multivariate analysis including both groups of patients revealed that age, functional class and year of operation significantly affected ten-year survival (p less than 0.05). The same analysis showed that coronary artery disease requiring coronary bypass surgery also decreased ten year survival in patients undergoing aortic valve replacement (p = 0.06).

Aged↗
PubMedDate not supplied

A current appraisal of the Waterston shunt.

Recent reports have suggested that the classical Blalock-Taussig shunt and its prosthetic modification have a low patency rate in neonates. This prompted a review of 58 neonates undergoing a Waterston shunt for cyanotic congenital heart disease. The 4 mm anastomosis was constructed using a calibrated clamp. There were 20 (35%) hospital deaths, of which 3 were directly related to shunt failure. Operative mortality was associated with increasing complexity of the cardiac lesion, emergency operation, weight less than 3 kg and age less than 48 hours. There were 5 late deaths resulting in an actuarial survival of 52% at ten years. There was one case of late occlusion corresponding to a patency of 92% at 2 years. Anastomotic kinking with preferential flow to one lung occurred in 2 (7%) of 28 patients undergoing repeat angiography at 3 and 5 years respectively. Nineteen patients underwent corrective surgery a mean of 27 months after shunt construction. Six (32%) required an angioplastic repair of the pulmonary artery. Six (16%) of the 38 operative survivors required diuretic therapy for excessive pulmonary flow. The high patency ensures that the Waterston shunt continues to play an important role in the management of low weight neonates who require an emergency systemic-pulmonary shunt. The use of a calibrated clamp reduces the incidence of excessive pulmonary flow. Early corrective surgery and shunt dismantling may reduce the necessity for angioplastic repair.

Aorta↗
PubMedDate not supplied

Changes in coronary bypass surgery leading to improved survival.

Coronary bypass surgery was performed on 439 patients between the years 1969 and 1973 (group A) and on 1,760 patients between the years 1974 and 1979 (group B). The operative mortality for group A was 3.9%; for group B, 1.3%; four-year survival for group A patients was 88.9% +/- 1.5% (mean +/- SE); for group B patients, 92.5% +/- 0.9%. The difference between the relative four-year survival rates (based on age- and sex-matched Oregon population) between group B and A was 6.2%; the lower operative mortality would account for only 2.6%. We conclude that the results of coronary bypass surgery have improved because of (1) a lower operative mortality, and (2) other factors that cannot be precisely defined at the present time but probably are the long-term result of better and more complete operative and perioperative techniques.

Adult↗