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Biomedical subjects

M Zimmerli

Publications and source records attributed to M Zimmerli.

10 recordsLinked to original sources
PubMed2001

Gender differences in coronary artery size per 100 g of left ventricular mass in a population without cardiac disease.

OBJECTIVES: To determine whether there is a gender difference in coronary artery size normalised for left ventricular (LV) mass. BACKGROUND: Small coronary artery caliber may play a role as a risk factor for coronary artery disease in women. However, the existence of a gender difference in coronary artery size is controversial. Furthermore, coronary artery size ought to be normalised for LV mass, since there is a theoretical relation of coronary artery size to LV mass according to the law of minimum viscous energy loss for the transport of blood in the coronary circulation. METHODS: In 200 individuals (100 women) without cardiac disease and with normal Doppler echocardiography, left main (LCA) and right coronary artery (RCA) size were determined using transoesophageal echocardiography. LV mass was assessed by transgastric M-mode echocardiography. RESULTS: Age (44 +/- 15 years in women; 41 +/- 16 years in men), the presence of non-cardiac diseases, cardiovascular risk factors and medication were similar in women and men. LV mass in women was lower than in men (148 +/- 36 g, 189 +/- 45 g; p < 0.0001). LCA and RCA cross-sectional areas in women were smaller than those in men (LCA: 10 +/- 3 and 16 +/- 5 mm2, p < 0.0001; RCA: 4 +/- 2 and 7 +/- 3 mm2, p < 0.0001, respectively). LCA and RCA cross-sectional areas of women were smaller even after normalisation for LV mass (LCA: 7 +/- 3 and 9 +/- 3 mm2/100 g LV mass, p < 0.0001; RCA: 3 +/- 1 and 4 +/- 1 mm2/100 g LV mass, p = 0.002, respectively). LCA caliber of women ranged below the theoretically expected size according to the law of minimum viscous energy loss for the transport of blood in the coronary circulation, whereas those of men tended to be above it. CONCLUSIONS: In a population without cardiac disease, women have smaller coronary artery size even after normalisation for left ventricular mass.

Adult↗
PubMed2001

Accurate determination of mitral regurgitation by assessing its influence on the combined diastolic mitral and pulmonary venous flow: just 'looking twice'.

AIMS: To assess the diagnostic accuracy of combined transmitral E wave velocity and reversed systolic pulmonary venous flow for the quantification of mitral regurgitation severity. METHODS AND RESULTS: Measuring forward and total left ventricular stroke volume, mitral regurgitation severity was assessed quantitatively by calculating the regurgitant fraction in 106 consecutive patients with pure mitral regurgitation. According to the regurgitant fraction, the optimal E wave velocity for accurate distinction of mild to moderate and more than moderate mitral regurgitation was chosen by calculating the receiver-operating characteristic plot. Severe mitral regurgitation was defined by reversed systolic pulmonary venous flow. Combining transmitral E wave velocity and reversed systolic pulmonary venous flow had an overall accuracy of 78% (95% CI 70--86%) for classification of mitral regurgitation severity. E wave velocity >1.0ms(-1) predicted more than moderate mitral regurgitation with 78% sensitivity (95% CI 69-86%) and 90% specificity (95% CI 82--95%), resulting in a positive likelihood ratio of 8.1 (95% CI 5--15) and negative likelihood ratio of 0.25 (95% CI 0.18--0.35). For reversed systolic pulmonary venous flow in the presence of increased E wave velocity, the sensitivity and specificity to detect severe mitral regurgitation was 78% (95% CI 69--86%) and 97% (95% CI 92--99%) with the corresponding positive and negative likelihood ratio of 29 (95% CI 11--96) and 0.22 (95% CI 0.14--0.31). Test accuracy was independent of systolic function in a multivariate regression analysis. CONCLUSIONS: 'Looking twice', once at the transmitral E wave velocity and once at pulmonary venous flow in patients with mitral regurgitation, allows accurate determination of moderately severe and severe mitral regurgitation.

Blood Flow Velocity↗
PubMed2001

Doppler tissue imaging for assessing left ventricular diastolic dysfunction in heart transplant rejection.

OBJECTIVE: To test the hypothesis that diastolic mitral annular motion velocity, as determined by Doppler tissue imaging and left ventricular diastolic flow propagation velocity, is related to the histological degree of heart transplant rejection according to the International Society of Heart and Lung Transplantation (ISHLT). METHODS: In 41 heart transplant recipients undergoing 151 myocardial biopsies, the following Doppler echocardiographic measurements were performed within one hour of biopsy: transmitral and pulmonary vein flow indices; mitral annular motion velocity indices; left ventricular diastolic flow propagation velocity. RESULTS: Late diastolic mitral annular motion velocity (A(DTI)) and mitral annular systolic contraction velocity (SC(DTI)) were higher in patients with ISHLT < IIIA than in those with ISHLT >/= IIIA (A(DTI), 8.8 cm/s v 7.7 cm/s (p = 0.03); SC(DTI), 19.3 cm/s v 9.3 cm/s (p < 0.05)). Sensitivity and specificity of A(DTI) < 8.7 cm/s (the best cut off value) in predicting significant heart transplant rejection were 82% and 53%, respectively. Early diastolic mitral annular motion velocity (E(DTI)) and flow propagation velocity were not related to the histological degree of heart transplant rejection. CONCLUSIONS: Doppler tissue imaging of the mitral annulus is useful in diagnosing heart transplant rejection because a high late diastolic mitral annular motion velocity can reliably exclude severe rejection. However, a reduced late diastolic mitral annular motion velocity cannot predict severe rejection reliably because it is not specific enough.

Blood Flow Velocity↗
PubMed1997

Long-term Doppler echocardiographic follow up in normally functioning aortic St. Jude Medical prosthesis.

BACKGROUND AND AIMS OF THE STUDY: Mean and peak Doppler gradients remain the most frequently used parameters for follow up of prosthetic aortic valves. Gradients that deviate from baseline recordings can lead to uncertainty among physician and patient, especially if symptoms have not completely subsided after surgery, or have recurred. This study aimed to document long-term evolution of mean and peak gradients in patients with stationary clinical symptoms and signs. METHODS: Seventy-six patients (48 men, 28 women), of mean age 56.1 +/- 14.5 years (range: 23 to 82 years) who underwent St. Jude Medical bileaflet prosthesis implantation were followed up for a mean of 3.9 years (range: 1 to 7 years), both clinically and echocardiographically. Evolution of mean and peak gradients, left ventricular function, other valvular lesions and rhythm as well as adequacy of anticoagulation were examined. RESULTS: Mean gradient increased from 12.3 +/- 5.5 to 14 +/- 5.7 mmHg (p = 0.002). Mean gradient increased in 47 patients, decreased in 17 and was unchanged in 12. There was no correlation between left ventricular function, appropriate anticoagulation, left ventricular hypertrophy, age or gender with change in mean or peak gradient. Change in peak gradient correlated excellently (r2 = 0.82) with that in mean gradient. CONCLUSIONS: The range of evolution of Doppler gradients in normally functioning St. Jude Medical prostheses has been defined in this study. Slight long-term increases in mean and peak pressure gradients are normal findings and do not warrant a change in management strategy if unaccompanied by deterioration of symptoms and/or clinical signs. Although we recommend routine determination of baseline flow measurements within three months of prosthesis implantation, mean and peak gradients are adequate follow up parameters. Peak gradient correlated well with mean gradient and may be a useful adjunct for follow up in clinical practice.

Aortic Valve↗
PubMed1991

Fluctuation of anti-A and anti-B histo-blood-group antibodies in a patient after liver transplantation.

The concentrations of anti-A and anti-B IgM and IgG antibodies have been studied in the serum of a patient with blood group AB who received a type A donor liver. A newly developed ABO-ELISA was used for this purpose and the values were compared to hemagglutination titers. During the postoperative study period over 8 weeks, the anti-A and anti-B levels showed a higher fluctuation than was measured in preoperative samples. Thus, in this AB-type patient, anti-A IgM varied 10-fold, anti-A IgG 20-fold and anti-B IgG 16-fold. Peak values corresponded to rejection episodes. Immunoactivation in the patient was further documented by the presence of abnormally high levels of soluble interleukin-2 receptors (sIL-2R) in serum samples. The study shows that monitoring of anti-A/B antibodies may represent a further criterion to follow-up transplanted patients during the critical postoperative graft acceptance period.

ABO Blood-Group System↗