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Biomedical subjects

K Bachmann

Publications and source records attributed to K Bachmann.

At least 73 records · Page 4Linked to original sources
PubMed1997

Coronary arteriography in elderly patients: risk, therapeutic consequences and long-term follow-up.

OBJECTIVE: Elderly people comprise the fastest-growing segment of the German population. This study evaluated the benefit of coronary arteriography in the management of selected old-age patients suffering from symptomatic coronary heart disease. METHOD: From 1982 to 1992, with annually increasing frequency, coronary arteriography was performed in 398 patients with suspected or proven coronary artery disease who were 75 years of age or older. RESULTS: Compared with 300 consecutive patients younger than 75 years, patients older than 75 years presented significantly more often with unstable angina, history of myocardial infarction, and multivessel disease; mean ejection fraction was significantly lower and risk of cardiac catheterization significantly higher. In more than half the older patients, balloon angioplasty (n = 130) or bypass surgery (n = 73) were judged to be indicated. Long-term prognosis was significantly worse with medical therapy: the 5-year survival rate was 58% for those receiving medical therapy, whereas it was 73% for those undergoing angioplasty, and 67% for those undergoing surgery. Multivariate analysis revealed history of diabetes and left ventricular ejection fraction as the most powerful predictors of death. Prognosis was significantly improved by surgery compared with medicine in patients with extensive coronary artery disease and impaired left ventricular function. More revascularized patients were free of angina at follow-up after a mean of 35 months, whereas intensity of antianginal medication was lower only in the surgically treated patients. CONCLUSIONS: In about half the selected aged patients, coronary angioplasty or bypass surgery was deemed feasible. Long-term prognosis, however, was primarily determined by left ventricular ejection fraction and history of diabetes. Compared with medical therapy, bypass surgery improved prognosis in patients with extensive coronary artery disease and impaired ventricular function. Interventions were effective in alleviating anginal complaints and reducing the need for antianginal drugs.

Age Factors↗
PubMed1996

[Diagnosis and therapy of cardiovascular diseases in elderly patients. Do different criteria apply?].

The risks associated with cardiac catheterization and coronary angiography increase with advancing age while at the same time, cardiovascular morbidity and mortality also rise. This means that the risks attendant on the two invasive diagnostic procedures can be accepted if they can be expected to identify the prognostically best form of treatment for the individual patient. Even in old age, CAD patients undergoing PTCA or coronary surgery are at an advantage in terms of long-term results and quality of life over patients receiving medical treatment only. From this it follows that the geriatric patient must not be excluded from such diagnostic and therapeutic procedures. Similarly, in the case of coronary thrombolysis following myocardial infarction, age per se must not be considered a contraindication. Finally, hypertension needs to be treated rigorously in the elderly too, albeit with consideration being given to certain differential therapeutic aspects.

Aged↗
PubMed1996

On-line evaluation of systolic performance by densitometry in digital left ventriculography.

The angiocardiographic evaluation of left ventricular end-diastolic (LVEDV) and end-systolic (LVESV) volumes and ejection fraction (EF) is routinely performed by the area-length method (ALM) but may lead to erroneous results. Digital imaging in real time allows densitometric procedures of determining left ventricular (LV) performance to be applied alternatively. In this study, we present densitometric algorithms for the analysis of LVEDV, LVESV, and EF from digital image data, establish accuracy and reproducibility, and determine value and limitations in comparison with ALM in single-plane 30 degrees right anterior oblique (RAO) projection. A linear relationship between iodine depth and measured densities is mainly burdened with scatter radiation and beam hardening which reduce primary radiation and suppress iodine depth. However, facilities such as deconvolution and correction algorithms are capable of reducing these sources of error. In the present study, computer-analyzed contrast images of iodine-filled wedges and spheres showed a near-linear relationship between iodine depth between 50-100 mg/cm2 and measured densities. Contrast images of heart casts and LV angio-grams of 54 patients were obtained with a digital image acquisition and processing system, and evaluated by two independent observers. The phantom study resulted in significantly (p < or = 0.01) better densitometric standard errors of estimate for volumes [3.3 ml densitometry (DENS) vs. 8.9 ml (ALM)] and simulated EF [4.3% (DENS) vs. 7.8% (ALM)] than ALM. The standard error of estimate for the comparison between both methods was 8.4 ml for volumes and 7.5% for EF. Densitometric volumes tended to underestimate volumes calculated by ALM. The angiographic study of patients demonstrated significant correlations between both methods (LVEDV r = 0.78, LVESV r = 0.83, total volumes: r = 0.89; EF r = 0.88). The standard errors of estimate can be ascribed to systematic, method-related errors of both DENS and ALM (LVEDV +/- 28.9 ml, LVESV +/- 23.4 ml, total volumes (EDV and ESV) +/- 27.1 ml; EF +/- 8.1%). The intra- and interobserver variability, respectively, exhibited significantly smaller (p < or = 0.01 and p < or = 0.05, respectively) standard errors of estimate for densitometric EF [4.6% (DENS) vs. 8.5% (ALM) and 7.1% (DENS) vs. 10.3% (ALM), respectively]. Inclined but not significant differences were found for LVEDV and LVESV. In conclusion, the data presented indicate that the calculation of LV volumes and EF in digital left ventriculography may be performed accurately by densitometric calculation in single-plane 30 degrees RAO projection. Minor underestimations in densitometric volume determination may be anticipated in the evaluation of LV geometry.

Adult↗
PubMed1996

Provocation of left ventricular outflow tract obstruction in patients with hypertrophic cardiomyopathy. Comparison of orthostasis testing and nitrate application.

Several provocation maneuvers are described in hypertrophic cardiomyopathy to Doppler echocardiographically distinguish the obstructive from the non obstructive type. No data are available about the value of orthostasis testing in comparison with nitrate application in this disease. In this study, 16 consecutive patients with hypertrophic cardiomyopathy were examined. 11 patients with hypertrophic cardiomyopathy were classified as obstructive, 5 patients with hypertrophic cardiomyopathy as non obstructive. Normal left ventricular outflow tract velocities as detected by the Doppler method were defined as < 2.0 m/s. Doppler echocardiographic measurements were performed after 10 minutes in supine position, within 10 minutes after head-up tilt and again, within 10 minutes in supine position. If systolic blood pressure during this examination exceeded 100 mm Hg 2.5 mg isosorbiddinitrate were sprayed sublingually. Measurements were done after 20 minutes in supine position and within 10 minutes after head-up tilt. Only in 7 of the 11 patients with hypertrophic obstructive cardiomyopathy maximal left ventricular outflow tract velocity in supine position measured > 2.0 m/s (2.2 +/- 0.8). During head-up tilt, all patients showed increased values (3.8 +/- 1.2 m/s). No differences in maximal left ventricular outflow tract velocity between head-up tilt and nitrate application in supine position (3.5 +/- 1.4 m/s) were present. All patients with hypertrophic non obstructive cardiomyopathy showed maximal left ventricular outflow tract velocities < 2.0 m/s in every step of the examination. Consequently, orthostasis testing was able to identify all patients with hypertrophic obstructive cardiomyopathy and demonstrated a diagnostic value similar to nitrate application.

Adult↗
PubMed1996

Evaluation of the non-invasive localization accuracy of cardiac arrhythmias attainable by multichannel magnetocardiography (MCG).

The accuracy of multichannel magnetocardiography (MCG) for the non-invasive localization of cardiac arrhythmias was investigated. A non-magnetic catheter was used in phantom studies and for cardiac pacing of 6 patients. In a clinical setting, 32 patients with WPW-syndrome, 37 patients with premature ventricular complexes and 12 patients with ventricular tachycardia were studied and the MCG results compared to reference methods, including invasive electrophysiological mapping. Phantom and pacing studies demonstrated the spatial localization accuracy to be better than 15 mm for a dipole-to-dewar distance below 15 cm. In all patients with structural cardiac disease, the ectopic focus was localized at the margin of the damaged area, serving as a proof of MCG localization. Invasive mapping confirmed the MCG result whenever performed (42 patients). In 11 patients (9 WPW, 2 VT) the MCG localization result was verified by successful HF catheter ablation as a gold standard. MCG permits the non-invasive localization of cardiac arrhythmias with high spatial accuracy. MCG guided HF catheter ablation constitutes a new concept of non-invasive localization and minimally invasive causal therapy.

Cardiac Pacing, Artificial↗
PubMed1996

Chlorzoxazone as a single sample probe of hepatic CYP2E1 activity in humans.

The objective of this investigation was to determine whether the oral clearance (CL) of chlorzoxazone could be estimated accurately from a single plasma chlorzoxazone measurement. In 6 healthy male subjects the mean clearance estimate (CLest) from a single 6-hour postdose measurement of plasma chlorzoxazone was within 6% of the actual mean CL calculated conventionally from the area under the plasma concentration versus time curve (AUC). After a second dose of chlorzoxazone administered 1 week later, the 6-hour mean CLest was within approximately 10% of the value from the previous week and within 15% of the value of CL from the previous week. No significant differences occurred between these three clearances, suggesting that for purposes of phenotyping CYP2E1 activity in humans with chlorzoxazone, a single-dose, single-sample procedure may suffice.

Adult↗
PubMed1996

Digital ventriculography: valid on-line calculation of cardiac volumes by corrected computer densitometry in coronary artery disease.

Cardiac catheterization facilitates the assessment of left ventricular function in coronary artery disease (CAD). Digital left ventriculography offers the potential for an on-line quantitative determination of left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume (LVESV). These are routinely evaluated by the area-length method (ALM), which is considered as a standard. Densitometry (DENS) is an alternative method but may lead to calculated underestimations. The purpose of this study was to investigate the accuracy of corrected DENS for LVEDV and LVESV in comparison with ALM in single-plane 30 degrees right anterior oblique (RAO) projection. The computer densitometric correction equation was adapted from the linear regression analysis (y = 0.86x + 2.73) in cardiac models and applied to the analysis of digital left ventriculograms in patients suffering from CAD. The study of cardiac models yielded highly significant correlations (r > or = 0.9; P < or = 0.001) between true volumes and both DENS and ALM. DENS and ALM correlated highly significantly (r > or = 0.9; P < or = 0.001) with a low standard error of estimate (SEE) of +/-9.5 mL. The comparison of DENS and ALM in 44 patients' digital ventriculograms exhibited highly significant (r = 0.74; P < or = 0.001) correlations for noncorrected and corrected LVEDV. Systematic underestimation by DENS of LVEDV disappeared after correction and SEE decreased from +/-23.7 to +/-19.2 mL. DENS and ALM correlated highly significantly for LVESV (r = 0.78; P < or = 0.001; SEE +/- 15.6 mL +/- 13.5 mL, respectively) after correction. Following correction, mean values for DENS increased from 116 +/- 32 to 132 +/- 37 mL (LVEDV) and 50 +/- 22 to 55 +/- 25 mL (LVESV). For ALM, mean values decreased from 159 +/- 35 to 127 +/- 28 mL (LVEDV) and 55 +/- 25 to 46 +/- 21 mL (LVESV). This study shows that LVEDV and LVESV can be reliably analyzed on-line by corrected computer densitometry. Method-related errors of both DENS and ALM are present and account for minor volume deviations.

Aged↗
PubMed1996

Scaling basic toxicokinetic parameters from rat to man.

Scaling of the quantified dispositional parameters of xenobiotics from animals to man is of interest from the standpoint of toxicology (e.g., poisoning and risk assessment). Scaling is also important from the standpoint of therapeutics because it represents a strategy for predicting first-use-in-human doses in clinical trials of investigational new drugs. Current strategies for scaling either doses of xenobiotics or the dispositional parameters of xenobiotics from animals to man rely on models that take account principally of species differences in weight or body surface area. Interspecies scaling of dispositional parameters such as clearance or volume of distribution commonly involves the comparison of estimates of these parameters for a given xenobiotic among numerous species on the basis of weight with the resultant mathematical relationship used to predict the values of those parameters for that xenobiotic in a species weighing, on average, about 70 kg (i.e., a man). Our approach has been to ascertain whether a useful mathematical model could be developed for predicting the dispositional parameters of a xenobiotic, its half-life and volume of distribution, in humans based exclusively on estimates of those parameters in rats. Based on a data set of about 100 different xenobiotics, we found that values for half-life and volume of distribution of a xenobiotic in humans can be predicted from the estimates of those parameters in rats.

Animals↗
PubMed1996

Improved densitometric analysis of ventricular volumes in on-line digital cardiac imaging.

In digital angiocardiography left ventricular volumes are routinely calculated by the area-length-method (ALM) which is considered to be a standard and with which other techniques are compared. Densitometric analysis (DENS) is an alternative method and can be performed on-line but may lead to erroneous results. A novel technique of densitometric calculation of left ventricular enddiastolic and endsystolic volume (LVEDV resp. LVESV) is presented. Digital images were analyzed by measuring densities of iodine signals and transforming these into calculated volumes by applying appropriate computer algorithms. The evaluation of volumes in cardiac models demonstrated significant correlations between true volumes and both DENS and ALM. An algorithmic approach to volume correction in patient evaluation of left ventricular volumes was drawn from the linear regression analysis of DENS and true volumes in the cardiac models. LVEDV and LVESV calculated by DENS correlated significantly with volumes determined by ALM in patients (r=0.78 resp. r=0.83) but showed a systematic underestimation for volumes > or =45 ml without densitometric correction. Following correction for DENS, an improvement in calculation was observed for volumes < or =200 ml without systematic deviations. In conclusion, our study demonstrates that corrected densitometric volumetry offers the potential for a reliable on-line analysis of enddiastolic and endsystolic volumes. Modest, but no systematic deviations for densitometric analysis may be anticipated in myogene dilatation with volumes larger than 200 ml. However, when comparing both DENS and ALM, method-related errors of both techniques are present and account for volume deviations.

Absorptiometry, Photon↗
PubMed1996

Analysis of adhesion molecules in myocardial biopsies of cardiac allografts and coronary artery disease with CABG.

Interactions of leukocytes with vascular endothelium are important components of inflammation tissue reactions and have been implicated in cardiac transplant rejection and demonstrated to be mediated by cell adhesion molecules (CAM's). The expression of ICAM-1, VCAM-1 and E-selectin in human myocardium is variable and little is known about the expression of LFA-1 and Mac-1 during allograft rejection. This study investigated these CAM's in myocardial biopsies of transplanted hearts (HTX) and of coronary artery disease eligible for coronary artery bypass grafting (CABG) as non-inflammatory controls and explicitly examines vascular endothelium, cardiomyocytes and infiltrating cells. Immunohistochemistry was performed using the APAAP-method and directing specific mouse anti-human monoclonal antibodies against ICAM-1 (CD54), VCAM-1 (CD106), E-selectin (CD62E), alpha-LFA-1 (CD11a), alpha-Mac-1 (CD11b), alpha-p150/95 (CD11c) and the beta2-integrin chain (CD18). CD18, LFA-1 (CD11a), Mac-1 (CD11b) and p150/95 (CD11c) were markedly expressed on infiltrating immunocytes in HTX compared to CABG where no expression of beta2-integrins was observed. Cardiac allografts demonstrated a strong expression of ICAM-1 on vascular endothelium and on infiltrating cells. ICAM-1 was not detected on cardiomyocytes. In CABG a weak expression of ICAM-1 was observed on endothelial cells but not on myocytes. VCAM-1 was expressed on vascular endothelium and perivascular infiltrating cells in HTX but not in CABG. VCAM-1 was not found to be expressed on myocytes. There was no evidence for the presence of E-selectin in any of our biopsy specimens. Our study shows that the study of cell adhesion molecules adds to the pathophysiological understanding of inflammation after transplantation in cardiac disease. This offers a potential for the development of diagnostic tools and new therapeutic strategies.

Biopsy↗
PubMed1996

Coronary angiography by electron beam tomography.

Electron Beam Tomography (EBT), a non-invasive imaging method with very high spatial and temporal resolution, is well suited for cardiac imaging. We established a protocol for the visualization of the coronary arteries by EBT and have so far evaluated the method in 88 patients. EBT imaging was performed using an Evolution scanner with a matrix of 512 x 512, a field of view of 15 cm and a slice thickness of 3 mm. After venous injection of contrast agent, 40 axial cross-sections of the heart were obtained triggered to the ECG at 80% of the R-R interval in inspiratory breathhold. With a lower threshold of 80 HU, 3D reconstructions of the heart and coronary arteries were rendered using shaded-surface display and maximum-intensity projection techniques. In all patients, the coronary arteries and, if present, aorto-coronary bypass grafts, were evaluated as to their visibility and presence or absence of haemodynamically relevant stenoses. All results were compared to the X-ray angiograms obtained by selective catheterization in a blinded manner. In 90% of cases, image quality was sufficient for evaluation. In 10% of the investigations, the EBT images could not be evaluated, mainly due to respiration artifacts. While the left anterior descending coronary artery was represented in very good image quality, the right coronary artery and left circumflex coronary artery showed decreased image quality due to motion artifacts and close correlation to venous structures such as the coronary sinus and atrial appendages. In a subgroup of 30 patients in which EBT results were compared to quantitative coronary angiography, the correlation of the vessel diameter in EBT and quantitative angiography was 0.82. Twelve out of 14 high-grade stenoses and 5/5 occlusions of the left anterior descending coronary artery as well as 3/4 highgrade stenoses and 1/2 occlusions of the right coronary artery and 2/4 high-grade stenoses of the left circumflex coronary artery were correctly identified. Nine patients were reinvestigated by EBT after successful angioplasty of high-grade coronary artery stenoses. The increase in vessel diameter could be documented in all cases. Twelve patients had a total of 28 aorto-coronary bypass grafts. Except for one mammarian artery graft which could not be evaluated due to small vessel lumen and clip artifacts, graft patency (21 cases) or occlusion (6 cases) was correctly diagnosed by EBT. EBT is a non-invasive method which permits the visualization of the coronary arteries. Stenoses of coronary artery bypass grafts and of the left anterior descending coronary artery can be reliably diagnosed, while reduced image quality, mainly due to faster vessel motion, impairs the results obtained for the right and left circumflex coronary artery.

Adult↗
PubMed1996

[Coronary angiography in patients over 80 years of age. Therapeutic consequences and long-term follow-up].

Today, an increasing number of old and very old patients is referred for invasive cardiovascular procedures. At our institution, cardiac catheterization has been performed in 82 patients 80 years of age or older (50 m, 32 f; mean age 82 +/- 2 years) during the last 11 years; in 70 patients, because of clinically proven or suspected coronary heart disease, and in 12 patients, because of heart valve disease. In comparison with younger patients, elderly patients with coronary heart disease more often presented with unstable angina, or had multivessel disease and reduced ejection fractions. PTCA (n = 25) and bypass grafting (n = 7) aimed at revascularization in 32 patients; in 38 patients, medical treatment was continued. Furthermore, valve replacement (n = 7) or valvuloplasty (n = 1) were judged to be indicated in 8 of the 12 patients with heart valve disease. Diagnostic procedure was more frequently burdened with serious complications in elderly than in younger patients (5/82 versus 3/300, p < 0.01). During follow-up of 25 +/- 23, median 21 months, cardiovascular events were significantly less frequent in patients with coronary heart disease who had undergone revascularization procedures than in those with medical therapy (2/29 versus 9/36; p = 0.05); more revascularized patients were free of angina at the time of reevaluation. Thus, risks of invasive diagnostic procedures are increased in very old patients. Diagnostics, however, result in therapeutical consequences, revascularization obviously improves symptomatology and prognosis in patients at extremely advanced age suffering from coronary heart disease.

Aged↗
PubMed1996

[Post-traumatic aneurysma spurium of the right atrium].

In a 61 year old male with heart failure and pulmonary congestion the x-ray shows a right paracardial tumor. The patient suffered from a blunt chest trauma 6 years ago. Since that accident he complains about exercise related dyspnea and cardiac arrhythmia with atrial fibrillation. On echocardiography we found a echolucent cystic tumor with a solid center structure surrounded by a thin membrane. Doppler echocardiography revealed a heart cycle dependent flow at its margin. During dextrocardiography rapid opacification only of the peripheral structures of the tumor could be observed. These findings are consistent with a traumatic rupture of the right atrium, and the diagnosis of a posttraumatic aneurysma spurium of the right atrium was established. Surgery confirmed this diagnosis and the aneurysm was extirpated.

Aneurysm, False↗
PubMed1996

Ambulatory blood pressure monitoring: quantification of the early morning rise in blood pressure in normal case and in patients with symptoms of orthostatic dysregulation.

Though various parameters can be evaluated in ambulatory blood pressure monitoring, there is still a lack of reliable parameters for exact quantification of the early morning rise. Noninvasive ambulatory blood pressure monitoring (Space Labs 90207) was performed in 50 normotensive persons and in 52 patients with symptoms of orthostatic dysregulation. Twenty-two of the 52 patients showed normal and 19 showed sympathicotonic reactions in the orthostatic test by Thulesius. After smoothing the 24-h blood pressure profiles by Fourier analysis, the derivative was calculated from the profiles (differentiation) and the following parameters were determined: the beginning and the length of the early morning rise as well as time and point of the maximum rise. The maximum rise was compared to the difference between the nocturnal trough and the morning peak (absolute value) as well as to the percentage rise, where we found significant statistic correlations. Patients with sympathicotonic orthostatic dysregulation showed in comparison to the 50 normotensive persons a significantly lower (p < 0.05) maximum rise in blood pressure. Thus, Fourier analysis of 24-h blood pressure profiles allows determination of reliable parameters of the early morning rise in blood pressure and can be used for more precise differential diagnosis in patients with orthostatic dysregulation.

Adult↗
PubMed1995

Controlled study of the putative interaction between famotidine and theophylline in patients with chronic obstructive pulmonary disease.

The effects of famotidine (80 mg per day), cimetidine (1600 mg per day), and placebo on theophylline pharmacokinetic parameters in chronic obstructive pulmonary disease (COPD) patients were compared. This was an open-label, randomized, three-period cross-over study, in which each subject first underwent a seven-day theophylline washout period, and thereafter received three single intravenous doses of theophylline (5 mg/kg infused over 30 minutes) during the study. Each of the experimental treatments was administered orally every 12 hours for a total of 9.5 days (19 doses). Theophylline was infused after the 17th dose of each treatment. Fourteen serial blood samples were collected before the start of each infusion, and for 30 hours after the end of each infusion. Plasma samples were assayed for theophylline, pharmacokinetic parameters were estimated, and treatment effects on each parameter were compared. Fourteen COPD patients completed all three periods of the investigation. Famotidine treatment had virtually no effect on any of theophylline's pharmacokinetic parameters. In contrast, cimetidine treatment significantly altered every pharmacokinetic parameter of theophylline as follows: Cimetidine decreased theophylline geometric mean CL from 2.74 L/h to 2.07 L/h (P < .001), and prolonged theophylline harmonic mean half-life from 6.6 to 9.6 hours (P < .001) and mean residence time from 10.8 to 15.0 hours (P < .001). Cimetidine treatment slightly increased theophylline volume of distribution by approximately 10%, and that change also was statistically significant (P = .032). The authors conclude that the treatment effects of cimetidine on theophylline pharmacokinetic parameters were in accord with those reported by others, and that famotidine treatment had no effect on any of theophylline's pharmacokinetic parameters in COPD patients.

Adult↗
PubMed1995

Coronary artery stenoses: three-dimensional imaging with electrocardiographically triggered, contrast agent-enhanced, electron-beam CT.

PURPOSE: To compare electron-beam computed tomography (CT) and coronary angiography for depiction of coronary artery stenoses. MATERIALS AND METHODS: In 27 patients (age range, 50-70 years), electrocardiographically triggered axial electron-beam CT scans of the heart were obtained during breath hold and intravenous administration of contrast agent. Coronary arteries were reconstructed three-dimensionally. Electron-beam CT and angiographic results were compared. RESULTS: Significant enhancement within the vessel lumen (P < .001) permitted selective reconstruction of the inner coronary artery lumen. Nine of 11 high-grade stenoses and all five occlusions in the proximal left anterior descending artery and three of five high-grade right coronary artery stenoses were clearly identified. Recognition of stenosis of the left circumflex artery was not reliable. Success after percutaneous transfemoral coronary angioplasty was documented in five of five patients by visualizing the increase in vessel diameter at repeat investigation. CONCLUSION: Contrast-enhanced electron-beam CT yields promising results concerning the visualization of coronary artery stenoses.

Aged↗
PubMed1995

Doppler echocardiographic determination of geometric orifice areas in mechanical aortic valve prostheses.

In 63 St. Jude bileaflet and 34 Bjoerk-Shiley tilting disk aortic valve prostheses, Doppler continuity areas were compared to their corresponding geometric areas defined by the opening angle of the occluders. Continuity areas correlated significantly with geometric areas in Bjoerk-Shiley (p = 0.68) and St. Jude prostheses (p = 0.86). Differences between continuity and geometric areas were greater in St. Jude than in Bjoerk-Shiley valves (0.87 +/- 0.45 cm2 vs. 0.06 +/- 0.47 cm2, p < 0.0001). Exclusion of patients with atrial fibrillation, with a postoperative interval of less than 1 year or valve sizes of 19 and 21 mm did not change the results. Thus, underestimation of geometric areas is present in the St. Jude bileaflet aortic valves, while geometric and continuity areas are not significantly different in Bjoerk-Shiley prostheses. These results are attributable to the effect of valve-type-dependent velocity profiles.

Adult↗