Global Left Ventricular Sphericity Index

The global left ventricular sphericity index:

Ventricular size and shape are the two geometric aspects that change in dilated hearts. The quantitative anatomic observations of Lindbach, in 1960 described the consistent finding of a more spherical shape within the expanded size of the abnormal geometry of remodeled ventricle [75]. This concept of increased sphericity has led to the development of the sphericity index, as a way to quantify the abnormal geometric changes that accompany heart failure in dilated failing left ventricles.

A heamodynamically significant PDA is associated with volume overload and LV remodeling.

Left ventricular (LV) remodeling manifests as an increase in LV end-diastolic and end-systolic volumes, an increase in myocardial

Long axis (L) length is measured in apical 4-chamber view from the apex to the mid-point of the mitral valve at end-diastole, and short axis (S) length is measured as the axis that perpendicularly intersects the mid-point of the long axis [76,79].

A decrease in the index of sphericity to less than 1.5 would support LV dilation and eccentric remodeling [84].

The relationship between the left ventricular chamber dimensions and body weight is not linear, so SI may be useful to tell if the left ventricle is dilated or not [76].

As prognosis is a surrogate of the extent of dilation [77,78], SI has a prognostic significance in a patient with a dilated left ventricle.

Sphericity index was also found to correlate significantly with the degree of mitral regurgitation in a cohort of patients with dilated cardiomyopathy [76]. Increased LV sphericity also results in greater MR [80,81].

Direction of shunt and pulmonary arterial pressure:

Spectral Doppler is a great tool to estimate the pulmonary artery pressure by measuring the ductal flow velocity as well as the pulmonary insufficiency velocity, if present [51].

• With isolated left to right shunt, with small to moderate sized patent ductus arteriosus and normal or mildly elevated pulmonary artery pressure, Doppler examination of duct shows continuous flow toward the transducer with peak in late systole.

• In large duct with pulmonary arterial hypertension, there will be bi-directional shunting on Doppler imaging of duct, right-to-left in systole and left to right in diastole.

• With increasing pulmonary vascular resistance as with no step up in oxygen saturation above and below the duct, peak of right-to-left shunting appear early in