Left Ventricle

Subvalvular obstruction may be dynamic or fixed. Hypertrophic cardiomyopathy, which may present at any age, is discussed earlier in this chapter. Discrete subaortic stenosis may be caused by a thin membrane in the LV outflow tract, a fibromuscular ridge, or diffuse muscular narrowing of the outflow tract (B*;B; Figs. 13-122A and E-nBi B, Plate 72) .Ml 2D echocardiographic imaging can distinguish these various forms of discrete subvalvular stenosis, and Doppler analysis permits estimation of the systolic gradient.6!2 Color-flow imaging demonstrates increased turbulence in the LVOT as well as aortic valvular regurgitation in about 50 percent of cases. Apical views are sometimes more useful for detecting thin subaortic membranes, as these structures are parallel to the ultrasound beam on parasternal images (E-hB; Fig. 13-122). Subaortic fibromuscular ridges are sometimes associated with anomalous mitral valve chordae connecting the papillary muscles or the anterior mitral valve leaflet to the septum.613,614 M-mode imaging may reveal midsystolic partial closure of the aortic valve, differentiating subvalvular from valvular AS.

Bicuspid aortic valve is the most common congenital cardiac lesion in adults and is present in 1 to 2 percent of all individuals (men are affected more often than women).615,616 Initially, eccentric diastolic coaptation of the aortic cusps was reported on M-mode in patients with bicuspid valves. However, M-mode findings are less accurate than 2D imaging, and the parasternal short-axis view is generally best for defining the fish-mouthed systolic aortic valvular anatomy (Q+iSi Figs. 13-60 and B-nBi 13-61). Bicuspid valves are sometimes easy to detect in diastole as well, but raphes and remnants of commissures may obscure the diagnosis and mimic a trileaflet valve. In general, asymmetry of the aortic leaflets suggests congenital deformation. In equivocal cases, multiplane TEE is usually diagnostic (B->;B; Fig. 13-61).

Ventricular Inflow Tract Abnormalities

Ebstein's anomaly is a congenital deformity of the tricuspid valve in which the leaflets are displaced into the right ventricle. Associated findings include TR, right atrial enlargement, and ASD.617,618 2D imaging typically shows abnormal apical displacement of the septal leaflet insertion, with variable deformity of the leaflet (Fig. 13-123). The anterior leaflet originates from the tricuspid annulus but is elongated and often tethered to the RV free wall by abnormal chordal attachments. The tricuspid deformity and regurgitation are best visualized in the apical four-chamber view, although the subcostal and modified parasternal views also may be helpful.

Subcostal Five Chamber View Fetal

Figure 13-123: Apical four-chamber image of Ebstein's anomaly. The right heart is enlarged, and the insertion of the septal leaflet of the tricuspid valve is displaced apically. The anterior tricuspid leaflet (to the patient's right) is abnormally elongated. RV = right ventricle; RA = right atrium; LA = left atrium; LV = left ventricle. (Reproduced with permission of Joseph A. Kisslo, MD.)

Figure 13-123: Apical four-chamber image of Ebstein's anomaly. The right heart is enlarged, and the insertion of the septal leaflet of the tricuspid valve is displaced apically. The anterior tricuspid leaflet (to the patient's right) is abnormally elongated. RV = right ventricle; RA = right atrium; LA = left atrium; LV = left ventricle. (Reproduced with permission of Joseph A. Kisslo, MD.)

Atrioventricular valvular atresia is usually accompanied by hypoplasia of the corresponding ventricle. Echocardiographic images of tricuspid atresia characteristically show a small, nonfunctional right ventricle, an interatrial communication of variable size, and a normally developed left ventricle. Associated lesions include VSD, transposition, and RV outflow obstruction. Echocardiography is an important tool in the management of patients with tricuspid atresia after palliation with the Fontan procedure. Mitral atresia is associated with a hypoplastic LV. Additional rare congenital mitral anomalies imaged by echocardiography include parachute mitral valve and congenital MS.

Fetal Echocardiography

The average risk for significant heart disease in the fetus is approximately 0.4 to 0.8 percent. Fetal echocardiography has evolved over the past 14 years into a sophisticated method for intrauterine detection of cardiac abnormalities640 (H-hQ; Fig. 13-124). The technique has been advocated for the preterm diagnosis of congenital heart disease, especially in higher-risk cases [for example, maternal congenital heart disease or diabetes mellitus, maternal teratogen exposure or toxoplasmosis, other intrauterine infections, rubella, cytomegalovirus, and herpes virus (TORCH) infection, and familial syndromes that may affect the heart].620 Fetal echocardiography has successfully identified a variety of congenital lesions including atrial and ventricular septal defect, pulmonic stenosis, transposition, tetralogy of Fallot, hypoplastic left heart, Ebstein's anomaly, and tricuspid atresia.621 Prenatal detection of these lesions may improve prognosis and guide therapy. Although some have recommended routine limited fetal echocardiography during the second or third trimester,620 recent reports have suggested a low yield and limited diagnostic accuracy.622-624 Like many imaging techniques, fetal echocardiography is evolving, and further study is required to define its optimal clinical use.

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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  • paola
    WHAT IS THE DIAGNOSIS CODE FOR LEFT VENTRICULAR INFLOW TRACT?
    7 years ago

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