PURPOSE: In clinical heart failure, inefficient propagation of blood volume through the left ventricle (LV) may result from suboptimal vortex formation ability of the LV during early diastole. We sought to: 1) validate transthoracic echocardiographic-derived vortex formation index (VFI) in normal subjects and 2) examine its utility in the evaluation of LV performance in both systolic and diastolic heart failure.
METHODS: Echocardiography (echo) was performed in 100 normal controls and 140 patients admitted with heart failure (100, systolic and 40, isolated diastolic failure). Patients with significant valvular heart disease were excluded. In addition to biplane LV ejection fraction (EF) and conventional parameters, the Tei index and tissue Doppler (TD) indices were also measured. VFI was obtained from the formula 4X(1-β)/πXα3XLVEF where β is the fraction of total transmitral diastolic stroke volume contributed by atrial contraction (assessed by time velocity integral of the mitral E and A waves) and α is cube root of biplane end diastolic volume divided by mitral annular diameter during early diastole.
RESULTS: Mean VFI was 2.75±0.7 in control subjects; reduced in heart failure, diastolic, 2.20±0.9; systolic, 1.22±0.5 (P<0.001, Fig 1). It correlated positively with TD derived early diastolic myocardial velocities (E', septal, r=0.60; lateral, r=0.59, both P<0.001); inversely with LV filling pressure (E/E’ septal, r=-0.44; lateral, r=-0.44, both P<0.001) and the Tei index (r=-0.57, P<0.001, curvilinear relation, Fig 2); and poorly with late diastolic TD velocities (A', septal, r=0.17, P=0.007; lateral, r=0.16, P=0.012). VFI was a more sensitive index in defining diastolic heart failure than other echo indices. In comparison with age, sex and LVEF-matched controls, only VFI remained significantly different (attenuated) in diastolic heart failure patients (2.01±0.7 vs 2.74±0.8, P=0.005).
CONCLUSION: This novel dimensionless index, incorporating LV geometry, systolic and diastolic contributions to fluid dynamics is a sensitive indicator of myocardial performance.
CLINICAL IMPLICATIONS: Using readily available transthoracic echo, VFI may be a useful adjunct in heart failure diagnosis and management.
DISCLOSURE: Kian Keong Poh, No Financial Disclosure Information; No Product/Research Disclosure Information