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Biomedical subjects

H Wellens

Publications and source records attributed to H Wellens.

8 recordsLinked to original sources
PubMed1999

Atherosclerosis in APOE*3-Leiden transgenic mice: from proliferative to atheromatous stage.

BACKGROUND: This study documents (1) the progression of atherosclerosis along the entire arterial tree in APOE*3-Leiden mice after 1, 4, 6, 9, and 12 months of a high-fat/high-cholesterol (HFC) diet and (2) the amount and phenotype of DNA-synthesizing and apoptotic cells in different lesion types after 6 months of HFC diet. METHODS AND RESULTS: Diet duration was correlated with a craniocaudal progression of lesion development and with an increase in severity of the lesion. Typically, the lesions contained smooth muscle cells, macrophages, and T lymphocytes and were covered by an intact endothelium. Whereas DNA synthesis (BrdU uptake) was usually elevated in type II lesions (8.6+/-0.8% versus 1.0+/-0.2% in the nondiseased arterial wall; P<0.05), apoptosis was found primarily in advanced lesions (type IV, 1.3+/-0.1% and type V, 1.2+/-0.2% versus 0.04+/-0.04% in the nondiseased arterial wall [P<0.05]). Cell phenotyping revealed that the majority of DNA synthesis and apoptosis was confined to the macrophage-derived foam cell (68.6+/-3. 0% and 82.2+/-4.6%, respectively). CONCLUSIONS: This study shows that in APOE*3-Leiden mice, duration of an HFC diet is associated with (1) a craniocaudal progression of lesion development and (2) an increased complexity of atherosclerotic lesions. Furthermore, DNA synthesis is predominant in early lesions, whereas apoptosis is present mainly in more advanced lesions. Both parameters of cell turnover are confined primarily to the macrophage-derived foam cell.

Animals↗
PubMed1996

A decision-making process in shared governance.

Shared governance teams require a good decision making process. After identifying the root cause of a problem, finding a solution that addresses the right issues begins. An issues flow chart and decision-making process were developed to help teams better identify and solve problems.

Decision Making, Organizational↗
PubMed1994

Initial experience with mode switching in a dual sensor, dual chamber pacemaker in patients with paroxysmal atrial tachyarrhythmias.

Mode switching algorithms have been developed to avoid tracking of atrial fibrillation (AF) or flutter (AFL) during DDD(R) pacing. Upon recognition of AF or AFL, the mode is switched to a nontracking, sensor driven mode. The Vitatron Diamond model 800 pacemaker does this on a beat-to-beat basis. Atrial events occurring within a "physiological range" (+/- 15 beats/min) calculated from a running average of the atrial rate are tracked. When atrial events are not tracked the escape interval is either determined by the sensor(s) or by a fallback algorithm thereby preventing large increases in V-V interval during mode switching. Loss of atrioventricular (AV) synchrony by atrial premature beats and after an episode of AF or AFL is prevented by atrial synchronization pulses (ASP), which are delivered after a safe interval (timed out from the sensed premature atrial event) has expired and before delivery of the next ventricular stimulus. We implanted 26 such devices in 18 men and 8 women with symptomatic second- or third-degree AV block and paroxysmal AF or AFL. Their ages ranged from 18-84 years (mean 60), and the follow-up ranged from 2-13 months (mean 8). During pacemaker check-up, exercise testing or 24-hour Holter monitoring one or more episodes of mode switching was documented in 8 patients. In these 8 patients a smooth transition (ventricular rate) from sinus rhythm to AF or AFL was documented on one or more occasions, without inappropriate increase in ventricular rate in the DDDR mode. None of the patients complained of palpitations.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Applicability of the stimulus-T interval for antitachycardia pacing.

UNLABELLED: At the onset of tachycardia, the refractory period (RP) changes together with the tachycardia termination window. We evaluated dogs with total atrioventricular (AV) block to determine if stimulus-T interval (STI) can be used to adjust the coupling interval(s) of an antitachycardia pacemaker in relation to changes in RP. Endocardial STI was recorded continuously together with six surface ECG leads. Steady-state (greater than 2 min) RP was determined for drive cycle lengths (DCL) 400 msec and 900 msec. The test pulse (TP) coupling interval, with DCL 900 msec, was chosen to be equal to the RP of DCL 400 msec. DCL was then changed to 400 msec until TP captured. STI of DCL of beat before capture was gained was measured. DCL was then changed back to 900 msec and the interval determined when capture was lost. TP was then lengthened by 5 msec and the procedure repeated until TP captured immediately upon changing to DCL 400 msec. RESULTS: The difference between RP at onset of pacing at DCL of 400 msec and RP when capture was achieved with the shortest coupling interval was 35-50 (mean 40) msec. This required 35-90 (mean 62) seconds. The correlation coefficient RP to STI was greater than 0.95. CONCLUSIONS: (1) RP changed by as much as 35-50 msec at the onset of an abrupt increase in rate in a 35-90-second period; and (2) STI enables estimation of RP on a beat-to-beat basis. Capture can therefore be predicted from the previous beat and the coupling interval adjusted accordingly in an antitachycardia pacing mode.

Animals↗
PubMed1977

Location and size of acute transmural myocardial infarction estimated from thallium-201 scintiscans. A clinicopathological study.

A clinicopathological study was performed in 23 patients who died from acute transmural myocardial infarction and who had been studied with thallium-201 during the acute phase. Twenty patients died within five days and three later than five days after scintigraphy. The scintigraphic location and the estimated size of infarction in vivo were correlated with postmortem findings. There was good agreement in 91% between scintigraphic and postmortem location of infarction and in 70% between the ECG and postmortem findings. The size of infarction as determined from computer-processed schematic drawings of postmortem slices of the heart correlated well with the size determined from processed schematic drawings of the scintiscans (r = 0.91 for anterior infarction, r = 0.97 for inferior infarction, r = 0.86 for anterior-inferior infarction). It is concluded that thallium-201 scintigraphy provided more precise location of infarction than the ECG and that the size of the scintigraphically abnormal area reflected the extent of necrotic myocardium.

Humans↗