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Abstract
To annalyze the characteristics of left ventricular(LV) outflow jets, transmitral flow and to define the effect of postural change on peak LV outflow jet velocity, twelve patients with hypertrophic obstructive cardiomyopathy were studied using M-mode, two dimensional echocardiography and Doppler echocardiography. Asymmetrical septal hypertrophy was present in all patients. Systolic anterior motion(SAM) fo mitral valve was present in 11 patients on M-mode and two dimensional echocardiography.
In all patients, high velocity jets were recorded at the site of SAM-septal contact with pulsed wave(PW) and high pulsed repetetion frequency(HPRE)-PW Doppler mapping method. HPRE-PW velocities in this region were the same as those obtained from continious wave Doppler recordings. Mean peak velocity in LV outflow jet was 3.7±0.4m/sec(range 1.3 to 5.1) and mean time to peak velocity in LV outflow jet as a ratio of ejection time(AT.ET) was 0.64±0.1.
In ten patients, time interval from onset of SAM to septal contact and duration of SAM-septal contact as a percentage of systolic time were correlated with peak velocities and pressure gradients significantly rose by standing(3.8±0.5 to 5.3±0.5m/sec, 63±14 to 119±18mmHg, p<0.025, respectively).
Eleven out of 12 patients had mitral regurgutation detected by Doppler echocardiography. Five of them had moderate to severe and 6 mild mitral regurgitation. The ratio of early to late diastolic filling velocitis(E/A) ohthe left ventricule was 1,5±0.9 in 4 patients with significant regurgitation. E/A ratio in 6 patient with mild MR and one patient without MR was 1.0±0.4.
These findings on Doppler echocardiography and provocation with standing support the concept that true obstruction is present in patients with hypertrophic cardiomyopathy. Diastolic filling abnormalities are present in patient without significant mitral regurgitation.
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