DK2985_C000 1..28 - AlSharqia Echo Club

82 Transesophageal Echocardiography(A)(B)LVRVLAAo(C)AORTIC FLOW(D)LVOT FLOWFigure 4.36 (A, B) Deep transgastric view of the left ventricular outflow tract (LVOT). (C) Corresponding aortic pulsed-wave Dopplerinterrogation. (D) LVOT pulsed-wave Doppler interrogation (Ao, aorta; LA, left atrium; LV, left ventricle; RV, right ventricle).contraction period (both atrioventricular and semilunarvalves closed) followed by the ejection time (ET) duringwhich blood is expelled from the ventricles into thegreat arteries. The amount of blood ejected per cardiaccycle, or stroke volume (SV), multiplied by the numberof cardiac cycles per minute, or heart rate (HR), yieldsthe cardiac output (CO) (see Chapter 5, equation 5.10).Diastole is more complex and is divided into fourphases: isovolumic relaxation, rapid filling, diastasis, andatrial contraction. It begins with AoV closure and endswith mitral valve closure. The period between AoVclosure and mitral valve opening is defined as the isovolumicrelaxation time (IVRT) and is a period of active(energy-requiring) and rapid ventricular relaxation. Onopening of the mitral valve, rapid initial filling of the ventriclefrom the atria occurs driven by the pressure gradientbetween the two chambers. Normally 70–80% of ventricularfilling occurs during this rapid filling phase. A(A)(B)AoVLATVRAPVRVFigure 4.37 Basal short-axis view of the aortic valve (AoV) (LA, left atrium; PV, pulmonic valve; RA, right atrium; RV, rightventricle; TV, tricuspid valve).