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Suppression of left ventricular early diastolic filling by long axis asynchrony
1Cardiac Department, Royal Brompton National Heart and Lung Hospital, London.
Objective:
To assess how early diastolic transmitral flow is suppressed in a group of patients in whom effective ventricular filling occurred exclusively with atrial systole.
Design:
Prospective examination of the left ventricular transverse and longitudinal axes and transmitral Doppler flow.
Setting:
A tertiary referral centre for cardiac diseases.
Subjects:
20 patients (mean (SD) age 65 (10) years) with isolated transmitral late diastolic flow were studied. None had sinus tachycardia, prolonged PR interval or a summation flow pattern. 21 normal individuals of similar age served as controls.
Results:
The left ventricle was usually dilated, end diastolic diameter (6.6 (1.0) v 4.9 (0.5) cm, P < 0.001) and end systolic diameter (5.4 (1.1) v 3.3 (0.5) cm, P < 0.001) were both increased, and fractional shortening of the minor axis reduced (16 (7)% v 30 (10)%, P < 0.001) in patients in whom left ventricular early diastolic filling was absent compared with those of normal controls. Mitral valve opening was late after aortic valve closure (A2) (115 (30) v 60 (10) ms, P < 0.001). The minor axis increased during this period (30 (20)% v 8.6 (2.5)%, P < 0.001). Onset of detectable transmitral flow was further delayed after cusp separation (85 (25) v 25 (10) ms, P < 0.001). Left ventricular long axis function was very abnormal. Onset of shortening was delayed with respect to the q wave at the left and septal sites (150 (40) v 90 (20) ms and 145 (30) v 80 (10) ms respectively, P < 0.001) and major shortening occurred after, rather than before, A2 (25 (12) v -10 (2.5)% and 50 (30) v -6.6 (0.3)% total excursion, P < 0.001). Although the long axis lengthened a little at the start of early diastole, its dominant component occurred in late diastole to coincide with atrial systole. The relative A wave was thus greatly increased at both sites (67 (17) v 29 (6)% and 77 (13) v 33 (8)%, P < 0.001).
Conclusion:
Prolonged left ventricular long axis shortening and delayed onset of lengthening effectively suppress early diastolic transmitral flow even though the minor axis increases and mitral cusps separate apparently normally. This grossly asynchronous left ventricular relaxation may interfere with filling by dissipating normal ventricular restoring forces.