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Biomedical subjects

W Bircks

Publications and source records attributed to W Bircks.

At least 91 records · Page 5Linked to original sources
PubMed1983

Central hemodynamics at rest and during exercise after mitral valve replacement with different prostheses.

To compare the hemodynamic features of different prosthetic heart valves that have equal tissue anulus diameter (29 mm or comparable), 75 patients with isolated mitral valve replacement (19 with Björk-Shiley Standard [BS], five with Hall-Kaster [HK], seven with Ionescu-Shiley [IS], 12 with Lillehei-Kaster [LK], 12 with Starr-Edwards [type 6120, SE], and 20 with St. Jude Medical [SJ] prostheses) were reexamined approximately 1 year after operation by right and left heart catheterization while they were at rest and during bicycle exercise. Mean pulmonary artery and mean left atrial pressure were reduced significantly in all the groups postoperatively. However, pulmonary artery and left atrial pressure were somewhat lower after BS and SJ implantation than the comparable pressures in the other groups. Normal values were reached only in a small number of patients, and the cardiac index remained at the lower limit of normal. Average diastolic pressure gradients in patients at rest were 2.3 +/- 0.6 mm Hg after SJ, 4.5 +/- 1.6 after BS, 5.2 +/- 3.3 after HK, 5.3 +/- 1.6 after IS, 7.1 +/- 1.3 after LK, and 6.3 +/- 2.0 after SE implantation. Effective valve orifice areas were calculated to be 3.1 +/- 0.8 cm2 in the SJ group and 2.2 +/- 0.5 cm2 in the BS group and even smaller in the other groups. Total volume loss does not seem to be significantly different among the valve types reexamined as determined by left ventricular angiography. For hemodynamic reasons, of all those prosthetic valves we compared, the SJ prosthesis appears to perform best in terms of lowest pressure gradients and largest effective orifice areas.

Adolescent↗
PubMed1983

Late complications in patients with Björk-Shiley and St. Jude Medical heart valve replacement.

Valve-related complications after Björk-Shiley mitral valve implantation (n = 475), aortic valve implantation (n = 424), or mitral-aortic valve implantation (n = 119) were compared with those after St. Jude Medical mitral valve replacement (n = 173), aortic valve replacement (n = 152), or mitral-aortic valve replacement (n = 69). All patients were placed on anticoagulant therapy with phenprocoumon early after operation. All patients had a comparable follow-up time of approximately 23 months, which showed that cumulative thromboembolic rates were significantly higher after St. Jude valve implantation than after Björk-Shiley valve implantation. Reoperations were necessary because of valve thrombosis (0.46%), perivalvular leakage (2.2%), or prosthetic valve endocarditis with perivalvular regurgitation (0.46%). One Björk-Shiley mitral valve prosthesis had to be replaced because of fracture of the outlet strut. Without significant intergroup differences, hemorrhage due to anticoagulant treatment was the most frequent complication. Thromboembolic complications were significantly more frequent after Björk-Shiley mitral, aortic, and double valve replacements than after St. Jude valve implantation. This may lead to consideration of changes in the prophylaxis of thrombus formations in the St. Jude valve, especially in aortic valve replacements, in patients with sinus rhythm.

Adolescent↗
PubMed1983

[Late complications following Björk-Shiley and St. Jude Medical heart valve replacement].

Valve-related complications after Björk-Shiley mitral (n = 475), aortic (n = 424), or mitral-aortic implantation (n = 119) were compared to complications after St. Jude mitral (n = 173), aortic (n = 152), and St. Jude mitral and aortic (n = 63) replacements. The 1,018 consecutive patients with Björk-Shiley valves had been operated upon between 1974 and 1982, those with St. Jude valves between 1978 and 1982. All patients were placed on anticoagulant therapy with phenprocoumon early after operation and no significant intergroup differences in the effectiveness of the anticoagulant therapy were found. At a comparable follow-up time of approximately 23 months, 24 major thromboembolic episodes were observed after Björk-Shiley mitral (BSM) and 3 after St. Jude mitral valve implantation (SJM), corresponding to a thromboembolic rate of 2.82/100 patient years with BSM and 0.93/100 patient years with SJM. After aortic valve replacements, 1.93 events in 100 patient years occurred after Björk-Shiley aortic (BSA) and 0.73 after St. Jude aortic implantation (SJA). In patients with double valve replacements, these rates were 3.2 (BSM + BSA) and 0.88 (SJM + SJA), respectively. The cerebral vessels were involved in 52% and the arteries of the extremities in 22% of these major events. Six Björk-Shiley prostheses had to be replaced because of valve thrombosis. The overall incidence of severe hemorrhagic complications was 2.94/100 patient years in BSM and 1.79 in SJM. After aortic valve replacement, we found rates of 1.80/100 patient years (BSA) and 2.57/100 patient years (SJA), respectively. Intravascular hemolysis no longer seems to be a significant clinical problem. However, indications of red cell damage after heart valve replacement were significantly greater in patients with perivalvular leakage, valve thrombosis, or dysfunction than in those with normally functioning prostheses. Reoperations were necessary because of valve thrombosis (0.46%), perivalvular leakage (2.2%), or prosthetic valve endocarditis with concomitant perivalvular regurgitation (0.46%). One valve had to be replaced because of fracture of the outlet strut of a BSM prosthesis. Hemorrhage due to the anticoagulant treatment was thus the most frequent complication, without significant intergroup differences, while thromboembolic complications were significantly more frequent after Björk-Shiley mitral, aortic, and double valve replacements than after St. Jude implantation. This may lead to the consideration of a change in the prophylaxis of thrombus formations with the St. Jude valve, especially in aortic valve replacements with sinus rhythm.

Adolescent↗
PubMed1982

Effects of antiarrhythmic surgery on late ventricular potentials recorded by precordial signal averaging in patients with ventricular tachycardia.

In seven patients with documented ventricular tachycardia (VT) and prior myocardial infarction, late potentials (LP) were recorded at the end of or after the QRS complex from the body surface using high-gain amplification and the signal averaging technique (RC filter settings 100 to 300 Hz). In 6 to 7 patients VT could be initiated by programmed right ventricular stimulation; in one case, VT was inducible only from the left ventricle during surgery. Surgery was guided by epi- and endocardial mapping. In most cases besides resection of scar tissue, a partial or complete subendocardial encircling ventriculotomy was performed. Postoperatively, LPs were abolished in five cases, VT being no longer inducible. In the remaining two patients, LPs were still present. VT was still inducible in one of these two cases whereas in the other case, no programmed testing was done postoperatively. These data suggest that the abolition of LPs by surgery is closely related to the disappearance of the propensity to stimulus-induced VT. Thus, the averaging technique represents a new approach to the noninvasive control of the efficacy of surgery in patients with VT and prior myocardial infarction.

Adult↗
PubMed1982

Left-to-right shunt at atrial level due to anomalous venous connection of left lung: report of seven cases.

Our experience with seven patients with partial anomalous pulmonary venous connection (PAPVC) of the left lung, treated between 1955 and 1980, is reviewed. The developmental aspects and the hemodynamic effects of the anomaly are discussed, and the patterns of the abnormal venous connection in our patients are described. All the patients except one had an additional atrial septal defect (ASD). Treatment consisted in closure of the ASD and creation of a large anastomosis between the detached or ligated anomalous connecting vein and the left atrium, preferably the left auricular appendage. No operative or late deaths occurred; and except for atrial flutter, which lasted a few days in one case, there were no serious complications. The indication for repair, the problems of the anastomosis, and the points of postoperative attention are discussed.

Adolescent↗
PubMed1982

The surgical treatment of ventricular tachycardias. Simple aneurysmectomy versus electrophysiologically guided procedures.

Between 1971 and 1982, 41 patients were operated upon for recurrent sustained ventricular tachycardia. All but three had severe coronary artery disease with a history of myocardial infarction. In 10 patients (Group I) simple aneurysmectomy with or without aorta-coronary bypass grafting was done. Thirty-one patients (Group II) had an electrophysiologically guided procedure, mainly partial or complete encircling endocardial ventriculotomy (EEV) at the earliest source of electrical activity during ventricular tachycardia. The results in the two groups indicate a clear superiority of electrophysiologically guided procedures over a simple aneurysmectomy regarding early and late disappearance of tachycardiac rhythm problems (p = 0.01); the differences between the two groups in hospital mortality (p = 0.43) and long-term survival are not significant. We compared our data with results in 160 cases of simple aneurysmectomy and 224 cases of electrophysiologically guided operations recently published in the literature. This comparison confirms the higher efficiency of mapping-guided procedures in eradicating ventricular tachycardias. The improvements in hospital and long-term survival, again, are not significant.

Adult↗
PubMed1981

Preliminary clinical and hemodynamic results after mitral valve replacement using St. Jude Medical prostheses in comparison with the Björk-Shiley valve.

The clinical improvement and the hemodynamic performance at rest and during bicycle exercise in 12 patients one year after St. Jude Medical mitral valve (SJMM) replacement were compared to the results of 40 patients after Björk-Shiley mitral valve (BSM) implantation. In both groups subjective and functional improvement was significant. In the SJMM-group no thromboembolic event had occurred, while 5 patients suffered from embolism during the first postoperative year after BSM (12.5%). Hemolysis was significantly lower in BSM but remained subclinical in SJMM. This may be explained by a premature backward movement of the posterior leaflet of the SJMM-prosthesis in late diastole resulting in a change of flow pattern. Low resistance to blood flow in the SJMM-prosthesis could be verified by a smaller diastolic transvalvular gradient (SJMM: 2.8 +/- 1.1; BSM: 5.3 +/- 2.6 mmHg). In valves with equal tissue annulus diameters (29 mm) the calculated effective valve orifices were significantly different (SJMM: 2.83 +/- 1.3 cm2; BSM: 1.85 +/- 0.53 cm2). In both groups the mean pulmonary artery pressure was significantly reduced at the time of reinvestigation but increased under exercise. Durability may become a problem because of the 2 moving parts of SJMM but until now we have observed no malfunction. St. Jude Medical mitral valve seems to be a good alternative in heart valve replacement with prostheses of small sizes, both for the mitral and tricuspid valve.

Adolescent↗
PubMed1981

Surgical aspects of typical subaortic and atypical midventricular hypertrophic obstructive cardiomyopathy (HOCM).

Hypertrophic obstructive cardiomyopathy (HOCM) is a special form of left ventricular outflow tract obstruction. Clinical experience demonstrates 2 different types of HOCM of the left ventricle: the typical subaortic or subvalvular HOCM and the atypical midventricular form of myocardial obstruction. In a series of 108 patients operated upon, 96 had typical and 12 had atypical HOCM. Indications for surgical treatment were increase of clinical symptoms to class III or IV (NYHA) and unresponsiveness to drug therapy (beta-blocking agents, calcium-antagonists). The male: female ratio was 21:1. The mean age in the group with typical HOCM was 38.8 years, in the group with atypical HOCM 46.5 years. Transaortic myectomy (n = 85) was the predominant surgical approach for relief of isolated subaortic and midventricular obstruction. Patients with severe mitral insufficiency and mitral valve replacement were identified as a problematic group. The total hospital mortality was 8.3% (9 of 108 patients), 7.9% (7 of 96 patients) in the typical group, and 16.7% (2 of 12 patients) in the atypical group. Postoperative cardiological follow-up indicates the superior effect of surgery as compared to drug therapy. The late mortality for the medical group was 10% and for the postoperative group 2.5%. These facts support our recommendation for the surgical treatment of HOCM in symptomatic patients in clinical stages III and IV (NYHA).

Adult↗
PubMed1981

[Long-term results of coronary revascularization--clinical, angiographic and hemodynamic findings (author's transl)].

Clinical angiographic, and hemodynamic examinations were performed in 37 patients (mean age 54 +/- 6.5 years) with coronary heart disease 5.4 +/- 5.3 months and 57.0 +/- 15.3 months after coronary revascularisation. The results were compared with those of a preoperatively performed examination (8.1 +/- 5.9 months). Early postoperatively 57 per cent of the patients were free of angina and 32 per cent had marked relief, whereas preoperatively 73 per cent had severe angina (class III and class IV). Late postoperatively 51 per cent had no angina and 49 per cent had only slight or moderate angina. The patency rate of the aorto-coronary bypass grafts was 90 percent early and 83 per cent late postoperatively. Occlusions of the native coronary arteries proximal to the anastomosis were found in 26 per cent preoperatively, in 55 per cent early and in 84 per cent late postoperatively. The parameters of left ventricular function showed no significant alterations early and late postoperatively. The results demonstrate that the relief of angina, the patency rate of the aorto-coronary bypass grafts and the resting function of the left ventricle are approximately unchanged five years after coronary revascularisation.

Adult↗
PubMed1981

Preliminary results in mitral valve replacement with St. Jude medical prosthesis: comparison with the Björk-Shiley valve.

The clinical improvement and the hemodynamic performance at rest and during bicycle exercise in 22 patients 1 year after implantation of a St. Jude Medical mitral valve (SJMM) were compared with the results of 40 patients after implantation of a Björk-Shiley mitral valve (BSM). In both subjective and functional improvement were significant. In the SJMM group no thromboembolic event occurred, while five patients in the BSM group suffered from embolism during the first year postoperative year (12.5%). Hemolysis was significantly lower in the BSM group but remained subclinical in the SJMM group. This may be explained by a premature backward movement of the posterior leaflet of the SJMM prosthesis in the late diastole, which resulted in a change of flow pattern. Low resistance to blood flow in the SJMM prosthesis could be verified by a small diastolic transvalvular gradient. In valves with equal tissue annulus diameters (29 mm), the calculated effective valve orifices were significantly different (3.07 +/- 1.36 cm2 in SJMM, 1.85 +/- 0.53 cm2 in BSM). In both groups, the mean pulmonary artery pressure was significantly reduced at the time of reinvestigation but increased during exercise. Durability may become a problem because of the two moving parts of SJMM, but we have observed no malfunction. The SJMM appears to be a good alternative in mitral valve replacement.

Adult↗
PubMed1980

Straddling atrioventricular valves in biventricular hearts. Observations made in 5 cases.

The report concerns 5 patients with straddling or overriding atrioventricular valves. The overriding phenomenon was found 4 times in tricuspid, once in mitral position. In addition to this malformation, 2 patients had congenitally corrected transposition of the great arteries (CTGA), one patient had transposition of the great arteries (TGA), and another a double outlet right ventricle (DORV). In 2 instances corrective surgery was done without compromising the anatomical and functional integrity of the straddling valve. Three patients with straddling degree B-C received palliative procedures, the ventricular septal defect (VSD) was left open in order to save the straddling atrioventricular valve and pulmonary artery banding was done for protection of the pulmonary vascularity. One corrected patient died in the early postoperative period.

Adolescent↗
PubMed1980

[Videodensitometric and electromagnetic flow measurements in aorto coronary bypass grafts (author's transl)].

Electromagnetic flow measurements in aorto coronary bypass grafts and cine angiography were performed simultaneously during bypass surgery. Using the front velocities of injected boli of contrast medium the videodensitometric measurement (QVD) overestimates the electromagnetically measured flow (QEM) systematically about 20% (QVD = 1.26 . QEM = 4 ml/min; Syx = 10.8 ml/min; r = 0.97). During the passage of the front of the contrast medium through the videodensitometric measuring windows, the flow is altered by the injection about + 13.6 ml/min on an average.

Blood Flow Velocity↗