EARLY DIASTOLIC LEFT-VENTRICULAR INFLOW PRESSURES IN NORMAL SUBJECTS AND PATIENTS WITH DILATED CARDIOMYOPATHY - RECONSTRUCTION FROM, PULSEDDOPPLER-ECHOCARDIOGRAPHY

Objective-To estimate early diastolic left ventricular inflow pressure s in normal subjects and patients with dilated cardiomyopathy, and thu s to assess the potential effect of restoring forces. Methods-Early di astolic left ventricular inflow pressures were reconstructed using the ventricular blood as an accelerometer, by measuring velocity at 1 cm intervals within the left ventricle from mitral ring to apex by pulsed Doppler echocardiography, and differentiating the records to obtain t he acceleration. Aortic component of second heart sound (A2) was used to fix relative timings. The local pressure gradient was determined fr om the acceleration at each level, and the total pressure drop during the acceleration (+ peak PD) and deceleration (- peak PD) phases of th e filling interval were determined by summing the local increments. Th e total stroke volume (SV) at the left ventricular outflow tract and t he mitral stroke distances (MSD) were also determined, using the time- velocity integral at mitral ring level. Effective flow orifice area wa s thus SV/MSD. Inflow jet width across the mitral valve was estimated by cross sectional colour Doppler flow mapping. Patients-32 patients w ith dilated cardiomyopathy with a dominant mitral E or summation wave, and 24 normal subjects of similar ages. Results-Normal + peak PD was 3.9 (SD 0.7) v 7.4 (2.2) mm Hg in dilated cardiomyopathy (P < 0.01). N ormal - peak PD was 2.5 (0.9) v 5.6 (2.8) mm Hg in cardiomyopathy (P < 0.01). Normal effective flow orifice area was 5.9 (1.3) v 1.9 (0.8) [ range 0.9 similar to 3.7] cm(2) in cardiomyopathy (P < 0.01). This cor responded to 71 (18)% of the end systolic cavity cross section in norm als v 11 (6)% in dilated cardiomyopathy (P< 0.01). Normal cross sectio nal colour inflow jet width was 2.7 (0.3) v 1.5 (0.4) cm in cardiomyop athy (P < 0.01). The jet width correlated with flow width calculated f rom effective flow orifice area (r = 0.82, P < 0.01). Conclusions-(1) Total early diastolic positive and negative peak pressure drop are nor mally low, so that significant negative left ventricular pressures are not needed to explain normal resting early diastolic mitral flow velo cities. (2) These low pressure drops are only possible with a large ef fective orifice area approaching end systolic left ventricular cavity area. (3) Atrioventricular pressure drops are much greater in dilated cardiomyopathy, where increased inflow accelerations are due to reduce d effective flow orifice area. These disturbances will impair filling independently of any abnormality of relaxation or compliance.