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Biomedical subjects

D Lindblom

Publications and source records attributed to D Lindblom.

At least 37 records · Page 2Linked to original sources
PubMed1993

Doppler-derived pressure differences in normally functioning aortic valve prostheses. Studies in Björk-Shiley monostrut and Biocor porcine prostheses.

To determine the normal range of maximum and mean Doppler-derived pressure differences for mechanical and bioprosthetic valves in the aortic position, Doppler echocardiography was performed on 239 stable patients with normally functioning Björk-Shiley monostrut (BSM, n = 185) or Biocor porcine (n = 54) prostheses. The interval from aortic valve replacement to echocardiography was 3-9 days. Maximum and mean pressure differences were significantly greater in 21 mm than in 25 or 27 mm BSM prostheses. The pressure differences in 23 mm BSM valves did not diverge significantly from those in 21, 25 or 27 mm valves. The mean pressure difference did not exceed 30 mm Hg in any type or size of studied prosthesis. No significant differences were found in pressure gradients in comparisons between BSM and Biocor prostheses of corresponding sizes. The calculated velocity ratio for BSM prostheses was not significantly influenced by the valve size. We suggest that the normal range of Doppler-derived maximum and mean pressure differences determined in this study be adopted as reference in evaluations of aortic BSM and Biocor valve prostheses.

Aged↗
PubMed1992

Aortic valve replacement in octogenarians with aortic stenosis: a case-control study.

OBJECTIVES: This study was designed to compare the results of aortic valve replacement in patients greater than or equal to 80 years old with those in patients 65 to 75 years old. BACKGROUND: Aortic valve replacement may be potentially more complicated and require the use of more resources when performed in octogenarians rather than in younger patients. Few hard data on this possibility are available. METHODS: The study group comprises all 44 patients greater than or equal to 80 years old (mean age 82 years) who underwent aortic valve replacement at our institution between January 1981 and July 1989. A control group of 83 patients with a mean age of 70 years was matched with the study group for gender and approximate date of valve replacement. Before operation, 86% of the older patients versus 36% of the younger patients were in New York Heart Association functional class III or IV (p less than 0.001). Data were retrospectively collected from hospital records and a self-assessment telephone interview was conducted. RESULTS: The early mortality rate was 14% in the older group versus 4% in the younger group (p = 0.045). The duration of respirator support, intensive care and the total duration of the hospital stay did not differ significantly between groups. The incidence of postoperative low cardiac output syndrome was higher in the older group (p = 0.049), but the incidence of late valve-related complications was similar in the two groups. The 2-year survival rate (including data on patients who died early) was 73% in the older group and 90% in the younger group (p = NS). Six months postoperatively all patients but one were in functional class I or II. CONCLUSIONS: Although the patients greater than or equal to 80 years old had a poorer preoperative status than that of younger patients, aortic valve replacement in this group did not require more use of hospital resources and resulted in a clinical improvement comparable to that of younger patients.

Age Factors↗
PubMed1992

Strut fracture with Björk-Shiley 70 degrees convexo-concave valve. An international multi-institutional follow-up study.

Between 1980 and 1983, 831 Björk-Shiley 70 degrees convexo-concave prosthetic heart valves were implanted at five institutions in Sweden, Germany. The Netherlands, and Canada. As of January 1991, there were 34 outlet strut fractures occurring from 0.2 to 10.1 years (median = 4.6 years) after implantation. In addition, there were 28 sudden, unexplained deaths. The mortality after strut fracture was 84%. The mortality after emergency valve replacement for strut fracture was 50%. The 10-year actuarial fracture rate (standard error) was 10.5 (2.4)% for large (29-33 mm) valves vs. 3.3 (1.2)% for 21-27 mm valves (P less than 0.001). Within valve size groups, fracture rates for aortic and mitral valves were similar. Cox regression analysis found only valve size to be significantly associated with strut fracture. There is a further subgrouping of the valves according to the manufacturer: group I are the earlier large 29-33 mm) valves; group II are the later large valves; group III are the small size (21-27 mm) valves. The risk of strut fracture was highest in group I (12.3% at 10 years) with an approximatively constant hazard (1.4% per year). A comparison was made with a statistical model incorporating all cases reported to the manufacturer. This model estimates fracture rates approximately 63%-73% of those found in the present study. These findings lead us to recommend that group I patients should be considered for elective reoperation on an individual basis, giving careful attention to risk factors and contraindications.

Adolescent↗
PubMed1991

Management of deep sternal wound infection after cardiac surgery--Hanuman syndrome.

Deep sternal wound infection following open-heart surgery caused sternal osteitis in eight patients and mediastinitis in 27 during 1980-1989. The incidence of such infection was 0.5%. Infection was more common during the last 2 years than in 1980-1987 (0.8% vs. 0.4%), and when bilateral internal mammary artery grafts were dissected (3.2% vs. 0.6% when only one internal mammary artery was used). Cure of mediastinitis was achieved by primary closed irrigation in four of 13 patients and by primary open treatment in five of ten. Muscle flap was employed in totally ten patients and omentum in four before final elimination of infection. Of the 27 patients with mediastinitis, eight (30%) died in the post-operative period of cardiac failure (3 cases), disseminated infection (2), bleeding (2) or aspiration (1). The 5-year survival rate was 43%. Prosthetic value endocarditis caused one late death and necessitated one reoperation. If eradication of postoperative mediastinitis is not achieved by early diagnosis, debridement and closed irrigation, transposition of muscle or omentum should be considered.

Cardiac Surgical Procedures↗
PubMed1990

Long-term relative survival rates after heart valve replacement.

The calculation and comparison of relative survival rates after interventional studies is a method that permits correction for important demographic variables, thereby adjusting for the "background mortality" in the general population. Long-term relative survival rates were analyzed in a consecutive series of 2,805 Swedish patients who, on the basis of clinical symptoms, underwent aortic valve replacement (n = 1,741), mitral valve replacement (n = 792) and double (aortic plus mitral) valve replacement (n = 272) between 1969 and 1983. The follow-up period, which closed August 1, 1985, included 100% of patients and covered 16,822 patient-years. Autopsy was performed in 75% of all deaths. The results underscore previously well known differences between the long-term survival after aortic valve replacement and mitral or double valve replacement, whereas no differences were noted between mitral and double valve replacement. Within the subgroup undergoing aortic valve replacement, analysis of relative survival rates disclosed a highly significant (p less than 0.001) difference between patients operated on for aortic stenosis and those operated on for aortic regurgitation, representing a mortality rate more than twice as high in the latter group. This difference was of much lesser magnitude when analyzed in the standard (actuarial) way. With a low (less than 2.5%) operative mortality rate for patients undergoing isolated elective aortic valve replacement in the current era and with an acceptable incidence of late valve-related death (5.2% at 10 years), these results may justify aortic valve replacement earlier in the course of chronic aortic regurgitation to prevent irreversible myocardial damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1990

External defibrillation during reoperative heart surgery.

An inexpensive system for remote external defibrillation was evaluated in 25 patients undergoing repeat open-heart surgery. The system consists of a pair of self-adhesive pads connected with a remote bracket on which a standard pair of external shock electrodes are discharged. With this system 84% of the patients were successfully defibrillated: 12% converted spontaneously. The energy level at conversion was less than or equal to 200 Ws in 90% of the patients. There were no complications associated with the defibrillation procedure. By reducing the need for intrapericardial dissection this method shortens overall operating time and most probably decreases blood loss. The system can also be recommended for operations with a high risk of ventricular arrhythmia prior to pericardiotomy.

Cardiac Surgical Procedures↗
PubMed1989

Coronary artery bypass grafting in patients 70 years of age and older. Early and late results.

Ninety-four patients 70 years of age and older underwent coronary artery bypass grafting (CABG) between 1979 and 1985. Thirty-two percent were females. An internal mammary artery was used in 49% and concomitant cardiac procedures were performed in 51% of the operations. Early mortality was 12%. Five of 11 early deaths were from non-cardiac causes: ascending aortic disease (2), cerebral damage (2) and septicaemia (1). Postoperative morbidity included neurological complications in 16%, reoperation for bleeding in 12%, mediastinitis or sternal dehiscence in 4% and perioperative acute myocardial infarction in 4%. At follow-up, a median of 2.5 years after surgery, 83% were completely free from angina, 5% much improved, 9% improved and 3% had unchanged symptoms of angina. Actuarial survival, inclusive of early mortality, was 84% at 3 years. Female sex and concomitant cardiac surgery were common in elderly patients who had CABG. Early mortality from noncardiac causes and postoperative morbidity were increased but dramatic relief of symptoms was achieved in the majority of survivors.

Actuarial Analysis↗
PubMed1989

Heart valve replacement in septuagenarians.

Heart valve replacement was performed on 208 patients aged 70-80 years--aortic (AVR) in 172, mitral in 20 and both valves in 16 cases. All valves were of Björk-Shiley type, and all but six patients received maintenance oral anticoagulant therapy. The 100% follow-up comprised 744 patient-years (mean 4.0 years). The early mortality was 9.6% and was related to the complexity and urgency of surgery: After elective AVR for pure aortic stenosis the rate was 3.9%. Actuarial survival (early mortality excluded) was 79% at 5 years and 73% at 8 years overall, and 87% and 80% after AVR for stenosis. In the AVR group the relative (age- and -sex-adjusted) survival rate indicated a normalized survival pattern after the first year, with 87%, 'cure' rate (early mortality included), and the incidence of thromboembolism and of fatal bleeding complications equalled figures for younger patients. Mechanical heart valve implantation and maintenance anticoagulation thus seems to be safe treatment even in elderly patients, and eliminates need for valve re-replacement due to bioprosthetic degeneration.

Actuarial Analysis↗
PubMed1989

Mechanical failure of the Björk-Shiley valve. Updated follow-up and considerations on prophylactic rereplacement.

The early production series of the 29 to 31 mm 70-degree convexo-concave (CC70) Björk-Shiley heart valves constitutes a subgroup of CC70 values with an extra high risk of outlet strut fracture. The hazard function for mechanical failure among these valves has remained almost constant over a 7-year follow-up period, and the 7-year actuarial incidence of mechanical failure among these valves is 12.5%. Selected patients with these valves will be considered for prophylactic rereplacement.

Aortic Valve↗
PubMed1988

HLA-B27: an important genetic risk factor for lone aortic regurgitation and severe conduction system abnormalities.

PURPOSE: HLA-B27, an immunogenetic marker that is present in 8 percent of the white population around the world, has been found to be an important risk factor for the development of a group of rheumatic disorders, the seronegative spondyloarthropathies. Our objective was to assess the possible role of HLA-B27 and the associated inflammatory disease process in the development of lone aortic regurgitation. PATIENTS AND METHODS: A group of 91 patients with lone aortic regurgitation were studied by HLA typing and clinical and roentgenologic examination. RESULTS: The HLA-B27-associated inflammatory disease process was found to be the probable underlying cause in 15 to 20 percent of patients with lone aortic regurgitation of different degrees of severity. Furthermore, HLA-B27 was found in 88 percent of the male patients with the combination of aortic regurgitation and severe conduction system abnormalities. CONCLUSION: We suggest that this cardiac syndrome should be regarded as an HLA-B27-associated syndrome, sometimes part of ankylosing spondylitis or Reiter's disease, but just as often presenting without obvious rheumatic disease. The marker is thus an important and widely distributed risk factor not only for the development of rheumatic disease but also for acquired aortic regurgitation and sever conduction system abnormalities.

Aortic Valve Insufficiency↗
PubMed1988

Strut-fracture of a Björk-Shiley tilting disc valve diagnosed by echocardiography--a case report.

A 40-year-old man with Björk-Shiley valves implanted in the aortic and mitral positions nine months previously presented with central chest pain. Shortly after admission he developed clinical features consistent with left ventricular failure. Fracture of the mitral prosthesis was diagnosed by echocardiography. At emergency operation the outlet strut of the mitral valve was found to be fractured and the disc was in the left ventricle. The patient survived valve re-placement and is in good health four years later.

Acute Disease↗
PubMed1988

Long-term clinical results after combined aortic and mitral valve replacement.

The results after 282 consecutive double (aortic & mitral) valve replacements (DVR) are compared with our previously reported experience after mitral (MVR, n = 810) and aortic valve replacement (AVR, n = 1753). All but one patient received Björk-Shiley valves. The follow-up which closed on August 1, 1985 was 99.3% and covered 16,869 patient-years (mean 6.3 years/patient). Autopsies were performed in 74% of all fatalities. Early mortality rates were identical in the three patient groups, and late mortality did not differ between MVR and DVR patients. The fraction of valve-related mortality was similar in all groups. Anticoagulant-related bleeding was equally common in all patient groups. The incidences of thromboembolism, reoperation and valve failure did not differ between MVR and DVR patients, but were significantly higher than among AVR patients. With the exception of a slightly increased incidence of prosthetic valve endocarditis, the results after DVR equal those after MVR. In cases with severe mitral valve disease but borderline aortic valve disease, primary DVR is clearly justified and eliminates the need for, and risks of, a secondary AVR.

Aged↗
PubMed1988

Long-term clinical results after mitral valve replacement with the Björk-Shiley prosthesis.

The experience of 810 mitral valve replacements performed during a 15-year period (1969 to June 1983) is reported. All but one patient received a Björk-Shiley disc valve. Five different Björk-Shiley models were used (Delrin, n = 51; standard pyrolytic carbon, n = 307; convexo-concave with an opening angle of 60 degrees, n = 229; convexo-concave with an opening angle of 70 degrees, n = 123; and the Monostrut valve, n = 99). The follow-up was 99.8% complete and covered 4614 patient-years (mean 6.0 years). An autopsy was performed in 77% of all fatalities. Early mortality was 5.7% and decreased during the study period. The 5-, 10-, and 15-year actuarial survival rates (early mortality excluded) were 78%, 62%, and 51%, respectively, and the complication-free survival rates at the same time intervals were 67%, 51%, and 36%. Seven percent of early deaths and 25% of late deaths were valve related, and most of these were due to valve thrombosis. The incidence of valve thrombosis was significantly (p less than 0.0005) reduced after the introduction of the convexo-concave valves, and this reduction was achieved without any increase in bleeding complications. The only patient-related factor found to be related to postoperative thromboembolism was a history of preoperative embolism (p less than 0.05). Most events occurring after implant (death, embolism, valve thrombosis, reoperation, and valve failure) had a peak incidence during the first postoperative year, whereas anticoagulant-related bleedings occurred at a constant rate of 1.2/100 patient-years. The linearized incidence of embolism was 1.6/100 patient-years (actuarial incidence at 5 and 10 years 6.9% and 13.0%, respectively). Seven strut fractures occurred (0.2/100 patient-years, actuarial incidence at 5 and 10 years 1.1%), as did five instances of prosthetic valve endocarditis (0.1/100 patient-years, actuarial incidence at 5 and 10 years, 0.7% and 1.3%). A new concept of valve failure is presented and includes a distinction between events related to the surgical procedure (treatment failure; 1.9/100 patient-years, actuarial incidence at 5 and 10 years 11.0% and 13.5%) and events possibly related to the prosthesis (prosthetic failure; 1.1/100 patient-years, actuarial incidence at 5 and 10 years 7.0% and 8.0%).

Actuarial Analysis↗
PubMed1988

Long-term clinical results after aortic valve replacement with the Björk-Shiley prosthesis.

The results of 1753 consecutive aortic valve replacements performed during a 15-year period (1969 to June 1983) are reported. All patients received one of five models of the Björk-Shiley valve. The follow-up was 99.6% complete and covered 10,658 patient-years (mean 6.4 years). An autopsy was performed in 72% of all fatalities. Early mortality was 5.5%. The early mortality rate for patients undergoing isolated, elective aortic valve replacement between 1979 and 1983 was 2.3%. Five-, 10-, and 15-year actuarial survival rates (early mortality excluded) were 85%, 70%, and 54%, respectively, and complication-free survival rates at the same time intervals were 78%, 59%, and 42%. Eighteen percent of the late deaths were considered valve related. Anticoagulant-related hemorrhage was the single most common valve-related complication (1.4/100 patient-years) and the most common valve-related cause of death (0.3/100 patient-years). The incidences of embolism and valve thrombosis were closely related to the efficacy of the anticoagulant program. Fourteen of 19 valve thromboses occurred among 180 patients without anticoagulants. The incidences of embolism and valve thrombosis among 1573 patients with continuous anticoagulant treatment were 0.7 and 0.06/100 patient-years, respectively. Six strut fractures occurred, all in convexo-concave valves. There was no mechanical failure among the Monostrut valves. The incidence of "prosthetic failure" (ie, valve-related complications [not leakage] necessitating reoperation or causing the patient's death) was 0.6/100 patient-years. The incidence of embolism and prosthetic failure was similar for the different valve models, and these long-term results might therefore be considered representative for all Björk-Shiley aortic valves.

Anticoagulants↗