Transient Bradycardia Induced by Carotid Sinus Pressure Increases Outflow Obstruction in Hypertrophic Obstructive Cardiomyopathy but Not in Valvular Aortic Stenosis: Materials and Methods

Valvular AS was diagnosed by documenting a peak pressure gradient of at least 20 mm Hg by Doppler echocardiography across a stenotic aortic valve with or without calcification.
Ultrasound imaging was performed with the Aloka SSD-870 or 860 systems, with 2.5- and 3.5-MHz transducers (Aloka Ltd; Tokyo, Japan). Assessment of myocardial hypertrophy was performed by M-mode echocardiography in the long- and short-axis parasternal planes. Localization of the site of increasing instantaneous velocity in the outflow tract was accomplished using a pulsed Doppler transducer. Localization of “aliasing” was obtained using the color Doppler mode of the SSD-870 system in the apical five-chamber view.
The continuous Doppler mode was then used with constant two-dimensional echo updating of the anatomic features in order to obtain the outflow tract Doppler signals. Particular attention was paid to possible contamination by mitral regurgitation signals. The modified Bernoulli equation (pressure gradient=4Xmaximal flow velocity) was used to calculate the peak instantaneous pressure gradient across the outflow tract. canadian health and care mall

The presence and severity of mitral regurgitation were searched for by using color Doppler examination and continuous and pulsed Doppler examination of the inflow tract and left atrium in the apical four-chamber view. Mitral regurgitation was not detected at rest in 15 of 30 patients. SAM of the mitral valve was studied with M-mode echocardiography during simultaneous two-dimensional imaging in the long-axis left parasternal view. The time of onset, rate, and duration of this anterior motion were analyzed and compared with respect to the QRS complex before and during CSP. LV end-diastolic and end-systolic dimensions and the slope of systolic motion of the posterior LV wall were measured in M-mode echocardiography. Indirect recordings of the brachial pulses were also obtained.

Category: Bradycardia

Tags: carotid sinus pressure, hypertrophic obstructive cardiomyopathy, murmurs