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Biomedical subjects

R W Hacker

Publications and source records attributed to R W Hacker.

At least 19 recordsLinked to original sources
PubMed2001

Intermediate-term results with 1,019 carbomedics aortic valves.

BACKGROUND: A retrospective study was conducted to evaluate the intermediate-term outcome in patients with the Carbomedics aortic valve prosthesis. METHODS: The study included 1,019 primary valve replacements between 1989 and 1997. Seventy-two percent of patients were men; mean (standard deviation) age was 61 (10) years. The preoperative New York Heart Association functional class was III or IV in 70% of patients. Follow-up at 9 years was 99.6% complete, comprising 2,730 patient-years (mean, 2.7 years). RESULTS: Patient survival, including operative deaths, was 80% at 7 years. The linearized death rate was 2.9%/year. Statistically significant risk factors for mortality were diabetes, pure valve insufficiency, advanced age at operation, and advanced preoperative functional class. Linearized rates were thrombosis, 0.1%/year; thromboembolism, 1.0%/year; hemorrhage, 1.7%/year; endocarditis, 0.1%/year; paravalvular leak, 0.1%/year; reoperation, 0.1%/year; and all events, 3.0%/year. The 7-year estimates of freedom from complications were thrombosis, 99%; thromboembolism, 93%; hemorrhage, 89%; endocarditis, 99%; paravalvular leak, 99.7%; reoperation, 99%; and all events, 82%. No structural valve failure was observed. CONCLUSIONS: The low incidence of valve-related complications favors the continued use of the Carbomedics valve in the aortic position.

Adolescent↗
PubMed2001

Aortic root replacement versus aortic valve replacement: a case-match study.

BACKGROUND: There is increasing evidence that patients with aortic valve disease and dilatation of the ascending aorta are at risk for later dissection or rupture of the aortic wall when the dilated ascending aorta is not replaced or reinforced at the time of aortic valve replacement. In order to find out whether the more complex surgical procedure of aortic root replacement carries a higher early or late postoperative risk than isolated aortic valve replacement, we conducted a matched-pair study with patients of both groups. METHODS: Between June 1993 and August 1998, 100 consecutive patients with aortic valve disease and ectasia/aneurysm of the ascending aorta underwent replacement of the aortic valve and the ascending aorta with a CarboSeal composite graft (CarboSeal; Sulzer Carbo-Medics Inc, Austin, TX). Identical bileaflet valve prostheses (CarboMedics; Sulzer CarboMedics Inc, Austin, TX) were implanted during the same time period in 928 patients for aortic valve disease. On the basis of various preoperative clinical variables 100 patients with aortic valve replacement were matched to the 100 patients with replacement of the aortic root. The duration of follow-up for both groups was similar with 37 + 17 months (range, 9 to 70) for the CarboSeal group and 38 + 14 months (range, 13 to 65) for the CarboMedics group. Survival and morbidity were calculated by Kaplan-Meier analysis and risk-adjusted mortality was evaluated by multivariate analysis in a Cox regression model. RESULTS: The early postoperative mortality of 1% in the CarboSeal group and 4% in the CarboMedics group was insignificantly different. Although the overall survival rate at 5 years was lower (60.7% vs 86.3%; p = 0.13) in the CarboSeal group, the freedom from cardiac mortality and valve-related morbidity was similar in the two groups. CONCLUSIONS: Replacement of the ascending aorta and aortic valve can be performed with similar operative risk, valve-related morbidity, and late cardiac mortality as isolated aortic valve replacement.

Adult↗
PubMed2000

Replacement of the aortic valve and ascending aorta with a valved stentless composite graft: technical considerations and early clinical results.

BACKGROUND: Replacement of the aortic valve and the ascending aorta with a conduit consisting of a mechanical valve and a Dacron tube has become a fairly common procedure. Commercially available conduits employing xenografts are rarely used for the same purpose, because if a reoperation becomes necessary due to degeneration of the valve prosthesis, usually the entire conduit must be replaced. A composite graft with a stentless valve, such as we describe in this article, avoids this problem, because in case of reoperation only the valve cusps need to be resected and the tube graft may be left in place. METHODS: Surgical technique of replacement of the aortic valve and the ascending aorta with a stentless composite graft and early results of the procedure are presented. RESULTS: Hemodynamics of the graft soon after surgery were excellent, with an average systolic gradient of 8 mm Hg and no regurgitation across the valve. There were two reoperations for bleeding in the early postoperative period. CONCLUSIONS: The stentless composite graft we describe provides excellent hemodynamics, has no need for anticoagulation, and is expected to offer a benefit in case of reoperation.

Adult↗
PubMed1995

Intermediate clinical results after aortic valve replacement with the Carpentier-Edwards pericardial bioprosthesis.

From January 1986 through December 1993, 482 patients underwent aortic valve replacement with the Carpentier-Edwards pericardial bioprosthesis at our institution. Patients ranged in age from 26 to 87 years (mean, 72.5 +/- 7.1 years), and 59.8% of them were men. Pure or predominant aortic stenosis was the indication for operation in 80.1% of the patients. Most (75.4%) of the patients were in New York Heart Association functional class III or IV preoperatively because of dyspnea. Isolated aortic valve replacement was performed in 265 patients (55.0%). The most frequent concomitant procedure was aortocoronary bypass grafting (38.4%). All patients were followed up for as many as 7 years postoperatively (average, 1.7 +/- 1.7 years). Twenty-six patients (5.4%) died within 30 days postoperatively; 53 patients died during the remainder of the follow-up period. The actuarial survival rate was 74.0% +/- 3.6% at 5 years and 59.7% +/- 7.5% at 7 years postoperatively. There were 12 valve-related deaths, and these were due to endocarditis (n = 3), thromboembolism (n = 5), anticoagulant-related hemorrhage (n = 2), reoperation necessitated by structural deterioration (n = 1), and sudden death (n = 1). After 7 years, the freedom from thromboembolic events was 86.6% +/- 3.8%, the freedom from anticoagulant-related hemorrhage was 98.0% +/- 0.9%, and the freedom from reoperation was 90.9% +/- 8.3%. There was only one structural failure, and this occurred at 6 years postoperatively.

Actuarial Analysis↗
PubMed1983

[Death rate on a heart surgery waiting list].

Of 2398 patients on a waiting list for aorto-coronary bypass operation 42 (1.8%) died before operation during an average waiting time of four months. Comparing the diagnostic data of those who died on the waiting list and those after operation, there was an increased frequency of indicators to further progression of the coronary heart disease (angina at rest, three-vessel disease, main stem stenosis, left ventricular contraction abnormalities) in the group of those patients who had died on the waiting list. The significance of these various indicators was further high-lighted in their prognostic significance when taking into account different waiting periods of the various sub-groups.

Coronary Artery Bypass↗
PubMed1980

Perioperative myocardial infarction in coronary artery bypass surgery.

Perioperative myocardial infarction (PMI) as diagnosed by standard electrocardiograms (appearance of persistent Q-waves of at least 0.4 sec duration) and/or autopsy, occurred in 51 (3.8%) out of 1341 consecutive patients undergoing coronary artery bypass surgery using saphenous vein grafts. Retrospective analysis of the available data revealed that preoperative factors like sex, age, history of myocardial infarction, functional class, coronary risk factors, number of vessels diseased, and ventricular function had no influence on the incidence of PMI. However, intraoperative parameters, e.g., type and duration of cardiac arrest as well as technical errors leading to graft occlusion, significantly affected the incidence of PMI. The clinical relevance of PMI is indicated by a high early mortality of 25.5% as compared to 2.3% in patients without PMI. Improvement as well as complete alleviation of angina pectoris was less frequent in patients with PMI than in patients without PMI. The decrease in the rate of PMI from more than 18% in 1970 to less than 1% in 1978/79 confirms that such incidents should not be regarded as an inevitable risk but as a complication which can largely be avoided by proper operative technique.

Adult↗
PubMed1980

Influence of preoperative variables upon the results of coronary artery bypass surgery.

One thousand ninety-six consecutive patients who received aorta-to-coronary artery bypass vein grafts were followed up to 4 years postoperatively. The early mortality was 1.7%; the 4-year survival rate, computed by actuarial methods, was 93.1%; the incidence of peri-operative myocardial infarction was 1.9%. After 4 years, 94.4% of the patients were free of peri- and postoperative infarcts. Angina pectoris was relieved in 85.7% and eliminated in 62.8% of the survivors. An analysis of the effects of ten preoperative variables on operative results showed that operative risk (early mortality, perioperative myocardial infarction) was not influenced by any of the variables. Late results (4-year mortality, 4-year infarction rate), however, were negatively affected by impaired ventricular function. Symptomatic improvement was more pronounced in men than in women.

Journal Article↗
PubMed1977

[Technical problems in coronary bypass surgery (author's transl)].

The problem of selecting the most suitable operative technique for coronary bypass surgery is demonstrated by a comparison of the most current methods. The fact, that comparable results can be obtained by various technical modifications makes it appear reasonable to choose an method as simple as possible for routine. Therefore, the following procedure is recommended: Extra-corporeal circulation with hemodilution and systemic as well as local hypothermia. Distal anastomoses under ischemic cardiac arrest without vent. Proximal anastomoses under partial extra-corporeal circulation with the heart beating. Continuous suture technique for all anastomoses. Our own clinical results with 1,3% early mortality, 1% perioperative myocardial infarctions and 94% graft patency after 1 month prove the feasibility of this operative procedure.

Blood Volume↗
PubMed1976

[Silicone embolism, fat embolism, and fibrin thrombosis in dogs after extracorporeal circulation using a bubble-oxygenator (author's transl)].

Following extracorporeal circulation with a bubble oxygenator (Rygg-Kyvsgaard) silicone emboli were found in the brain-and-kidney-capillaries of all dogs evaluated. There was no obvious correlation between intensity of silicone embolism and pump time. No cellular reaction was seen around the anti-foam agent. Occasionally single small areas of embolic brain damage were found. During extracorporeal circulation and within a recovery period up to one hour no silicone excretion through the kidneys could be demonstrated. Systemic fat embolism occurred less frequent than previously reported. Use of a filter in the cardiotomy suction line reduced its intensity further. In neither of the various organs examined, disseminated intravascular thrombosis could be found.

Animals↗