ISSN:
1615-2573
Keywords:
Dilated cardiomyopathy
;
Doppler echocardiography
;
Left ventricular filling
;
Momentum flux
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary We studied the properties of the jet of blood entering the left ventricle from the left atrium during early diastole in 32 patients with dilated cardiomyopathy, and 24 normal subjects of similar age. The diameter of the jet was measured from the cross-sectional color Doppler image and its cross-sectional area (JA) was derived. Pulsed Doppler records of flow velocity were made at 1-cm intervals into the ventricle from the mitral ring. Peak (Vp) and mean (Vm) E wave velocity and time velocity integral (TVI) were determined. At any level in the ventricle, therefore, the early diastolic volume of blood remaining in the jet, i.e., the flow time integral, is given by JA·TVI; the local flow rate, Q, by JA·Vm; and jet momentum along the long axis of the ventricle by Q·Vp. In normals, the jet cross-sectional area fell from 5.9 (1.3) cm2 at the mitral ring to 4.9 (0.7) cm2 at 4 cm (P 〈 0.05), but the flow time integral fell proportionately more, from 46.0 (15.2) ml at the ring level to 15.9 (3.4) ml at 4cm (P 〈 0.01). Axial momentum flux was 44 (13) × 102cm4s−2 at the ring level, falling to 28 (10) × 102 cm4s−2 at 4 cm (P 〈 0.01). In dilated cardiomyopathy, the jet cross-sectional area was much smaller than normal, 1.9 (0.8) cm2 at the ring level, and it remained effectively constant, being 2.0 (0.9)cm2 at 6cm (P 〈 0.01 vs normals). The same applied to the flow time integral, which was reduced at the ring level (18.0 (10.3) mlP 〈 0.01 vs normal), and was unchanged at 5 cm. Axial momentum flux was higher than normal, 72 (33) × 102cm4s−2 at ring level (P 〈 0.01 vs normal), was unchanged at 4 cm, and fell at 6 cm to 43 (18) ×2cm4s−2 (bothP 〈 0.01 vs normal). Thus, axial momentum was rapidly lost from the incoming jet in the normals, prmarily due to loss of mass, suggesting forces acting perpendicularly to the ventricular long axis. In patients with dilated cardiomyopathy, the cross-sectional area of the jet was much smaller, less mass was lost from the jet, and momentum was maintained at least 4cm into the cavity, falling only slowly thereafter, suggesting that lateral forces are much less well developed in these patients.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01744987
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