17 research outputs found
Blood flow structure and dynamics, and ejection mechanism in the left ventricle: Analysis using echo-dynamography
SummaryUsing our âecho-dynamographyâ, blood flow structure and flow dynamics during ventricular systole were investigated in 10 normal volunteers. The velocity vector distribution demonstrated blood flow during ejection was laminar along the ventricular septum. The characteristic flow structure was observed in each cardiac phases, early, mid- and late systole and was generated depending on the wall dynamic events such as peristaltic squeezing, hinge-like movement of the mitral ring plane, bellows action of the ventricle and dimensional changes in the funnel shape of the basal part of the ventricle, which were disclosed macroscopically by using the new technology of high speed scanning echo-tomography and microscopically by the strain rate distribution measured by phase tracking method.The pump function was reflected on the changes in the flow structure represented by the flow axis line distribution and the acceleration along the flow axis line. The acceleration of the ejection had three modes, âAâ, âBâ and âCâ, and generated by the wall dynamic events. âAâ appeared from the apical to the outflow area along the main flow axis line, âBâ along the anterior mitral leaflet and the branched flow axis line, and âCâ generated by the high speed vortex behind the mitral valve. The magnitude of the acceleration was estimated quantitatively from the velocity gradient along the flow axis line. Macroscopic and microscopic asynchrony in the myocardial contraction and extension appeared systematically in the local part of the ventricular wall, which was helpful for making the flow structure and for performing the smooth pump function
Non-uniform distribution of the contraction/extension (CâE) in the left ventricular myocardium related to the myocardial function
AbstractObjectiveWe attempted to disclose the microscopic characteristics of the non-uniform distribution of the contraction and extension (CâE) of the left ventricular (LV) myocardium using a new methodology (echo-dynamography).MethodsThe distributions of the âaxial strain rateâ (aSR) and the intra-mural velocity in the local areas of the free wall including the posterior wall (PW) and interventricular septum (IVS) were microscopically obtained using echo-dynamography with a high accuracy of 821ÎŒm in the spatial resolution. The results were shown by the color M-mode echocardiogram or curvilinear graph. Subjects were 10 presumably normal volunteers.Results(1)Both the CâE in the pulsating LV wall showed non-uniformity spatially and time-sequentially.(2)The CâE property was better evaluated by the aSR distribution method rather than the intra-mural velocity distribution method.(3)Two types of non-uniformity of the aSR distribution were observed: i.e. (i) the difference of its (+)SR (contraction: C) or (â)SR (extension: E) was solely the âmagnitudeâ; (ii) the coexistence of both the (+) SR and (â)SR at the same time.(4)The aSR distribution during systole was either âspotted,â or âmulti-layered,â or âtonedâ distribution, whereas âstratified,â âtoned,â or âalternatingâ distributions were observed during diastole.(5)The aSR distribution in the longitudinal section plane was varied in the individual areas of the wall even during the same timing.(6)To the mechanical function of the LV, there was a different behavior between the IVS and PW.ConclusionsThe aSR and its distribution were the major determinants of the CâE property of the LV myocardium. Spatial as well as time-sequential uniformity of either contraction or extension did not exist. The myocardial function changed depending on the assemblage of the aSR distribution, and by the synergistic effect of (+)SR and (â)SR, the non-uniformity itself potentially served to hold the smooth LV mechanical function
Informed Consent in the Candesartan Antihypertensive Survival Evaluation in Japan (CASE-J) Trial: A Survey of Collaborating Physicians
Echophonocardiographic study of the initial low frequency component of the first heart sound
To investigate the genesis of the initial low frequency component of the first heart sound that precedes the high frequency vibrations associated with closure of the atrioventricular valves, echophonocardiograms of 36 persons were recorded. These included 10 normal subjects and 26 patients with various types of heart disease including mitral valve replacement. Electrocardiograms demonstrated normal sinus rhythm in 23 subjects, atrial fibrillation in 9, complete atrioventricular block in 2 and atrial flutter in 2. In the phonocardiogram, the low frequency component of the first heart sound followed the onset of the QRS complex and preceded the first high frequency component of this sound. The low frequency component occurred simultaneously with the beginning of the final fast closing movement of the mitral valve on he echocardiogram and was found both in normal rhythm and in arrhythmias. However, in arrhythmias its intensity varied on a beat to beat basis, being loudest after a short RR interval or when atrial systole occurred very close to the expected time of ventricular systole. In patients in whom apexcardiograms were recorded, the low frequency component was coincident with or very close to the onset of ventricular systole.It is concluded that the low frequency component of the first heart sound represents vibrations caused by contraction of the left ventricle and deceleration of antegrade blood flow across the mitral valve. Neither atrial contraction nor mitral valve tension is necessary for the production of this soft initial component
Physiological basis and clinical significance of left ventricular suction studied using echo-dynamography
SummaryBackgroundThe existence as well as the exact genesis of left ventricular suction during rapid filling phase have been controversial. In the present study, we aimed at resolution of this problem using noninvasive and sophisticated ultrasonic methods. The clinical meaning was also documented.MethodsTen healthy male volunteers were examined by 2D echocardiography and echo-dynamography which enables us to obtain detailed instantaneous data of blood flow and wall motion simultaneously from the wide range of the left ventricle. The correlation of blood flow and wall motion was also studied.ResultsRapid ventricular filling was divided into 2 phases which had different physiology. The early half (early rapid filling: ERF) showed the effect which was alike drawing a piston. This was proved by the shape of the velocity of inflow and the basal muscle contraction which actively assisted extension of the relaxed apical and central parts of the left ventricle, giving the negative pressure which causes the ventricular suction.The later half (late rapid filling: LRF) showed the turning of the fundamental flow and the squeezed basal part just like the sphincter in addition to the expansion of the apical and central portions of the left ventricle, and all of these cooperatively augmented the suction effect.ConclusionVentricular suction does exist to help ventricular filling. Simultaneous appearance of the contraction in the basal part and the relaxation or extension in the apical part during the post-ejection transitional period was made to occur the suction in the LV. And it can be said that the suction appeared in the late stage of systole as the one of the serial systolic phenomena