Biomedical subjects

H Mannaerts

Publications and source records attributed to H Mannaerts.

4 recordsLinked to original sources

PubMed2001

Quantitative assessment of mechanical prosthetic valve area by 3-dimensional transesophageal echocardiography.

OBJECTIVE: The goal of this study was to assess the geometric orifice area of mechanical valve prostheses by transesophageal 3-dimensional echocardiographic planimetry. METHODS AND RESULTS: Currently used Doppler methods for prosthetic assessment (orifice area-Doppler) were compared with 3D planimetry for orifice area (orifice area-3D) and with manufacturer's values (orifice area-manufacturer) for the corresponding prosthesis types and sizes and with historical controls provided by Doppler literature (orifice area-literature). Twenty-four mechanical valve prostheses (in 22 patients) were studied: 13 in mitral position and 11 in aortic position. Orifice area-manufacturer, orifice area-Doppler, orifice area-literature, and orifice area-3D were 3.6 +/- 1.1 cm(2), 2.3 +/- 0.9 cm(2), 2.4 +/- 0.9 cm(2), and 2.6 +/- 0.7 cm(2), respectively. Orifice area-manufacturer values were significantly larger. Correlation coefficients between orifice area-3D and orifice area-manufacturer, and between orifice area-3D and orifice area-Doppler and orifice area-literature were 0.83, 0.90, and 0.73, respectively (all P < .0001). CONCLUSION: Three-dimensional transesophageal echocardiography is feasible and has good correlation with orifice area-Doppler (in aortic position) and good correlation with orifice area-manufacturer (in aortic and mitral positions) methods.

Adult↗

PubMed1997

Influence of heart rate, respiration and recipient atrial contraction on pulsed wave transmitral Doppler flow indices in orthotopic heart transplant recipients.

AIMS: The study set out to assess the relative contributions of donor heart rate, respiration and recipient atrial contraction on the mean of pulsed wave transmitral Doppler flow indices in orthotopic heart transplant recipients. This would provide information on the theoretical usefulness of pacemaker synchronization of recipient atrial contraction, as well as on the validity of certain strategies used for pulsed wave Dopper analysis of diastolic left ventricular function, which have excluded beats based on recipient atrial contraction timing. METHODS: Thirty two consecutive patients undergoing orthotopic heart transplantation in our centre were prospectively studied. The following Doppler indices were analysed: peak early diastolic velocity (E) and its area under the Doppler curve (TVIE), diastolic velocity after donor atrial contraction (A) and its area under the curve (TVIA), the total area under the curve (TVI), the isovolumic relaxation period (IVR), the diastolic filling period, the normalized peak filling rate and the pressure half time. RESULTS: Only 81 out of 347 recordings (23%) allowed analysis of the recipient P wave and thus recipient atrial contraction timing, heart rate and the respiration phase in 22 patients for a total of 1579 beats. The isovolumic relaxation period, E, pressure half time and TVIA are not influenced by donor heart rate. For the isovolumic relaxation period, E, TVI and TVIE, respiration contributes as much as recipient atrial contraction timing to beat-to-beat variation. Pressure half time, the diastolic filling period and peak filling rate were not affected by respiration. TVI was not affected by recipient atrial contraction timing. CONCLUSION: With respect to analysis of diastolic function, exclusion of beats based on recipient atrial contraction timing is invalid for the isovolumic relaxation period. E, TVI and TVIE, since these are equally influenced by respiration. Since TVI was not affected by recipient atrial contraction timing, pacemaker synchronization of donor and recipient atria is not expected to be useful in patients with left ventricular diastolic dysfunction.

Atrial Function↗

PubMed1997

Auditory vertex potential in children: a cognitive hypothesis.

In children the early N1P2 response generated by an auditory oddball paradigm is a compound negative potential with distinctive 165-ms temporal and 240-ms frontocentral components. As this configuration differs considerably from the adult response, it may be assumed that neural systems engaged in auditory attentional processes differ with age. It is argued that the auditory vertex potential might index frontal lobe development and matching mechanisms. In combination with EEG spectral data this cognitive parameter could initiate an alternative approach to the evaluation and research of learning and attention deficit disorders.

Adult↗

PubMed1983

Immune response to hepatitis B vaccine in drug addicts.

Drug addicts are at high risk of hepatitis B infection and are therefore candidates for vaccination against hepatitis B. Since drug addicts may have an impaired immune response, and low compliance for therapy extending over several months, we evaluated a vaccination scheme according to the instruction of the manufacturer (HB- Vax 20 micrograms at zero, one and six months) in drug addicts using daily methadone (Group M), in drug addicts in residential detoxification programmes (Group D), and in treatment centre staff who were seronegative for hepatitis Bs (Group S). All 23 controls and 20 of 21 of Group D completed the vaccination programme, in contrast to 14 of 24 in Group M. Anti-HBs developed in 91 per cent of Group S and in all addicts tested at six months. Anti-HBs titres at seven months were higher than 100 RIA units in 55 per cent of Group S, in 94 per cent of Group D and in 44 per cent of Group M. We conclude that HB- Vax induces production of anti-HBs equally well in drug addicts and in controls: a shorter-duration vaccination schedule might be more appropriate for 'non-captive' drug addicts living outside therapeutic communities.

Hepatitis B↗