Biomedical subjects

Jan Forster

Publications and source records attributed to Jan Forster.

6 recordsLinked to original sources

PubMed2007

Altered left ventricular diastolic filling following a marathon is a reproducible phenomenon.

The present study examined the reproducibility of alterations in left ventricular function and cardiac biomarkers in a cohort of athletes following two marathons, one year apart. Eight participants in the 2004 and 2005 London Marathons were tested pre- and post-race via echocardiography and humoral analysis. Reductions in diastolic filling, unrelated to loading or heart rate, following both marathons were reproducible within individuals, which may be a function of exercise duration. In contrast, exercise-induced cardiac troponin release was inconsistent.

Adult↗

PubMed2006

Novel application of flow propagation velocity and ischaemia-modified albumin in analysis of postexercise cardiac function in man.

The present study employed novel echocardiographic tools and cardiac markers to obtain a greater understanding of the aetiology and time course of altered cardiac function and cardiac damage following prolonged exercise and, in particular, the possible role of transient ischaemia within these phenomena. Fourteen runners in the 2004 London Marathon were assessed pre-, immediately post-, 1 h post- and 24 h postcompletion of the race. Left ventricular function was examined echocardiographically using 2-D, M-mode, tissue Doppler imaging and flow propagation velocity (Vp). Venous blood samples were analysed for N-terminal pro-B-type natriuretic peptide (proBNP), cardiac troponin T (cTnT) and ischaemia-modified albumin (IMA). Left ventricular (LV) diastolic filling was altered on completion of the race, as indicated by significant decreases in mean early to late diastolic myocardial wave (E':A') ratio and Vp (from 1.82 +/- 0.9 to 1.32 +/- 0.32, and from 67.5 +/- 9.3 to 60.2 +/- 8.2 cm s(-1), respectively, P < 0.05), accompanied by an increase in proBNP (from 21.6 +/- 11 to 47.08 +/- 19.5 pg l(-1), P < 0.05). The observed reduction in LV diastolic filling following completion of a marathon, unrelated to changes in heart rate or loading parameters, indicates an intrinsically mediated change in diastolic filling. Exercise-induced elevations in cTnT in nine individuals (range, 0.023-0.37 microg l(-1)) were indicative of minor cardiac damage. A significant reduction in IMA was observed after the marathon (from 63.68 +/- 9.83 to 44.94 +/- 16.13 Um l(-1), P < 0.05), unrelated to the alterations in cardiac function, proBNP or cTnT. The absence of an elevation in IMA suggests that exercise-induced myocardial ischaemia did not occur and therefore could not explain the changes in cardiac function or biomarkers. Future studies in this area should investigate alternative diagnostic tools for the detection of transient ischaemia, and other potential mechanisms, in order to extend the understanding of this phenomenon.

Adult↗

PubMed2006

The impact of marathon running upon ventricular function as assessed by 2D, Doppler, and tissue-Doppler echocardiography.

The impact of prolonged exercise upon right ventricular (RV) function is poorly understood and to date no studies have utilized tissue-Doppler imaging (TDI). Thirty-five marathon runners (age range 18-50 years) volunteered for the study. Two-dimensional, pulsed Doppler, and TDI studies were performed one day before and immediately following race completion. Right and left ventricular (LV) longitudinal TDI myocardial velocities were acquired from the tricuspid annulus and mitral annulus, providing velocity data during systole (S'), early diastole (E'), and late diastole (A'). Transtricuspid and transmitral, early diastolic (E), and late diastolic (A) velocities and ratios were assessed using conventional pulsed-wave Doppler. RV and LV fractional area changes (FAC) were calculated from RV and LV end-diastolic and end-systolic areas recorded from 2D scans in a subsample (n = 23). RV myocardial velocities were unchanged pre-post race in S' (21.1 +/- 2.7 to 21.7 +/- 4.5 cm s(-1), P > 0.05), reduced in E' (23.3 +/- 3.5 to 19.9 +/- 5.3 cm s(-1), P < 0.05), increased in A' (19.1 +/- 3.6 to 23.7 +/- 6.8 cm s(-1), P < 0.05) with a resultant decline in E'/A' (1.28 +/- 0.36 to 0.94 +/- 0.45, P < 0.05). This pattern of data was mirrored in the LV. Similarly both pulsed-Doppler tricuspid and mitral E/A ratios decreased from pre- to postrace (P < 0.05). FAC for the RV and LV were unaltered postrace (P > 0.05). The impact of differing age, finishing time (173-330 min), hemodynamic loading and heart rate upon RV and LV function pre- to postrace was negligible. In conclusion, TDI and 2D data, for both the RV and LV demonstrated little change in systolic function after a marathon race. Conversely, a reduction in diastolic function was observed in both ventricles for which a mechanism has yet to be deduced.

Adolescent↗

PubMed2005

Mitral annular myocardial velocity assessment of segmental left ventricular diastolic function after prolonged exercise in humans.

We assessed segmental and global left ventricular (LV) diastolic function via tissue-Doppler imaging (TDI) as well as Doppler flow variables before and after a marathon race to extend our knowledge of exercise-induced changes in cardiac function. Twenty-nine subjects (age 18-62 year) volunteered to participate and were assessed pre- and post-race. Measurements of longitudinal plane TDI myocardial diastolic velocities at five sites on the mitral annulus included peak early myocardial tissue velocity (E'), peak late (or atrial) myocardial tissue velocity (A') and the ratio E'/A'. Standard pulsed-wave Doppler transmitral and pulmonary vein flow indices were also recorded along with measurements of body mass, heart rate, blood pressures and cardiac troponin T (cTnT), a biomarker of myocyte damage. Pre- to post-race changes in LV diastolic function were analysed by repeated measures ANOVA. Delta scores for LV diastolic function were correlated with each other and alterations in indices of LV loading. Diastolic longitudinal segmental and mean TDI data were altered post-race such that the mean E'/A' ratio was significantly depressed (1.51 +/- 0.34 to 1.16 +/- 0.35, P < 0.05). Changes in segmental and global TDI data were not related to an elevated post-race HR, a decreased post-race pre-load or an elevated cTnT. The pulsed wave Doppler ratio of peak early transmitral flow velocity (E)/peak late (or atrial) flow velocity (A) was also significantly reduced post-race (1.75 +/- 0.46 to 1.05 +/- 0.30, P < 0.05); however, it was significantly correlated with post-race changes in heart rate. The lack of change in E/E' from pre- to post-race (3.4 +/- 0.8 and 3.3 +/- 0.7, respectively) suggests that the depression in diastolic function is likely to be due to altered relaxation of the left ventricle; however, the exact aetiology of this change remains to be determined.

Adolescent↗

PubMed2005

A universal algorithm for an improved finite element mesh generation Mesh quality assessment in comparison to former automated mesh-generators and an analytic model.

The FE-modeling of complex anatomical structures is not solved satisfyingly so far. Voxel-based as opposed to contour-based algorithms allow an automated mesh generation based on the image data. Nonetheless their geometric precision is limited. We developed an automated mesh-generator that combines the advantages of voxel-based generation with improved representation of the geometry by displacement of nodes on the object-surface. Models of an artificial 3D-pipe-section and a skullbase were generated with different mesh-densities using the newly developed geometric, unsmoothed and smoothed voxel generators. Compared to the analytic calculation of the 3D-pipe-section model the normalized RMS error of the surface stress was 0.173-0.647 for the unsmoothed voxel models, 0.111-0.616 for the smoothed voxel models with small volume error and 0.126-0.273 for the geometric models. The highest element-energy error as a criterion for the mesh quality was 2.61x10(-2) N mm, 2.46x10(-2) N mm and 1.81x10(-2) N mm for unsmoothed, smoothed and geometric voxel models, respectively. The geometric model of the 3D-skullbase resulted in the lowest element-energy error and volume error. This algorithm also allowed the best representation of anatomical details. The presented geometric mesh-generator is universally applicable and allows an automated and accurate modeling by combining the advantages of the voxel-technique and of improved surface-modeling.

Algorithms↗

PubMed2005

Impact of marathon running on cardiac structure and function in recreational runners.

The present study examined the relationship between LV (left ventricular) function, markers of cardiac-specific damage and markers of oxidative stress in recreational runners following a marathon. Runners (n=52; 43 male and nine female; age, 35+/-10 years; height, 1.74+/-0.08 m; body mass, 75.9+/-8.9 kg) were assessed pre- and immediately post-marathon. LV function was assessed using standard M-mode two-dimensional Doppler echocardiography and TDI (tissue-Doppler imaging) echocardiography. Serum was analysed for cTnT (cardiac troponin-T), TEAC (Trolox equivalent antioxidant capacity; a measure of total antioxidant capacity), MDA (malondealdehyde) and 4-HNE (4-hydroxynonenal). A strong relationship was observed between standard and TDI echocardiography for all functional measures. Diastolic function was altered post-marathon characterized by a reduction in E (peak early diastolic filling: 0.79+/-0.11 compared with 0.64+/-0.16 cm/s; P<0.001), an increase in A (peak late diastolic filling: 0.48+/-0.11 compared with 0.60+/-0.12 cm/s; P<0.001) and a resultant decrease in E/A (ratio of E to A; 1.71+/-0.48 compared with 1.10+/-0.31; P<0.001). Ejection fraction remained unchanged post-marathon. Thirty-two runners presented with cTnT values above the lower limit of detection for the assay (0.01 microg/l), and 20 runners presented post-marathon with cTnT values above the acute myocardial infarction cut-off value (0.05 microg/l). No significant correlations were observed between cTnT and any functional measurements. MDA (2.90+/-1.58 compared with 3.59+/-1.47 micromol/l) and TEAC (1.80+/-0.12 compared with 1.89+/-0.21 mmol/l) were significantly increased post-marathon, but were unrelated to changes in function or cTnT. In conclusion, the present study demonstrated a reduction in diastolic function and widespread evidence of minimal cardiac damage following a marathon in recreational runners. The mechanism(s) underpinning the altered function and appearance of cTnT appear unrelated to reactive oxygen species.

Adolescent↗