Biomedical Engineering Reference
In-Depth Information
4.4.5 Rhythmicity
The ratio of atrial to ventricular beats per min was used to determine atrioventricular
(AV) ratio; AV ratio
1 indicated irregular AV rhythmicity.
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4.4.6 Circulation
Zebrafish heart development begins at early gastrulation. By 22hpf, the heart tube is
beating, and around 24hpf, circulation begins. Movement of blood cells through the
heart and major vessels, and the rate and pattern of blood flow were examined.
Abnormal circulation included defects in circulation rate (no, slow, or fast circu-
lation) and defects in circulatory pattern (circulation loop only observed in the head
or trunk).
4.4.7 Cardiac Morphology
Drug treatment was performed as described in the concentration range determination
assay. Cardiac morphology was examined under a Zeiss dissecting microscope
equipped with a SPOT Insight 10ZNC digital camera. After compound treatment,
representative images (at 8
magnification) were acquired. The zebrafish heart has
one atrium and one ventricle. In normal embryos, the atrium and ventricle are side by
side; the blood flows into the atrium from the sinus venosus and out of the ventricle
through the bulbus arteriosus. The heart is composed of concentric tubes of cells, an
outer myocardial layer, and an inner endocardial layer. Morphological abnormalities,
including the size of the heart and number and position of the heart chambers,
were examined.
4.4.8 Pericardial Edema
Pericardial edema refers to the presence of an abnormal volume of fluid in the space
surrounding heart chambers, which can be easily visualized in transparent zebra-
fish. Pericardial edema may be caused by venous or lymphatic obstruction,
increased vascular permeability, heart failure, or kidney disease. To assess if
drugs caused pericardial edema, we visually examined the presence of enlarged
heart chambers.
4.4.9 Hemorrhage/Thrombosis
Hemorrhage may be caused by rupture of blood vessels in a specific tissue or organ.
Thrombosis is defined as formation of a blood clot. In zebrafish, hemorrhage was
visualized as a pool of blood in a tissue or organ. Thrombosis was observed as a
stagnant blood flow or a blood clot in the cardinal vein.
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