The evaluation of right ventricular (RV) size and function in normal and pathologic conditions is challenging due to its complex shape and nonsymmetrical contraction. Unlike the left ventricle (LV), the RV is crescent shaped and truncated, with separate inflow and outflow portions. The normal RV is triangular (curved) when viewed sagittally, crescent shaped when viewed axially, and similar to a teapot when viewed coronally (Fig. 19–1). It is thin walled, highly trabeculated, and devoid of the LV's extensive circumferential myofibrillar architecture. The RV apex may be dominated by the shape and function of the LV apex or may be entirely separate and independent ("butterfly" apex) (Fig. 19–2).1 The RV is strongly influenced by the normally concave interventricular septum, and its shape is influenced by acute and chronic pathologic pressure and volume changes. Whereas the normal LV has the shape of a prolate ellipse (and becomes a sphere in many disease states), there is no convenient model that accurately approximates normal or pathologic RV geometry.
Representative cardiac magnetic resonance (CMR) white blood images. The normal right ventricle (RV) is crescent shaped when viewed axially (A), triangular (curved) when viewed sagittally (B and C), and similar to a teapot when viewed coronally (D).
A. Cardiac magnetic resonance imaging white blood (steady-state free precession) cine image. The right ventricular (RV) apex is entirely separate and independent from the left ventricular (LV) apex ("butterfly" apex; black arrow). Left. Diastole. Right. Systole. Note the thin hypokinetic RV apex in this normal patient (white arrow). B. Importance of foreshortening. This is a normal volunteer without heart disease. Note the left panel images (a = diastole; b = systole) that were obtained within minutes of the right panel images (c = diastole; d = systole). The image on the left was obtained with a slightly inferior angulation relative to the truly aligned four-chamber view on the right creating a foreshortened LV long axis diameter (dotted lines equal length). Due to the pyramidal RV shape, this inferior angulation creates an elongated RV cavity relative to the LV. This creates a falsely dilated RV cavity and also accentuates the RV apex, which appears separated from the LV ("butterfly") and hypokinetic (arrows). See Moving Image 19–2B.
Moving Image 19-2B.
Importance of foreshortening.
This chapter describes the unique characteristics ...