Abstract
Background
Vortex Formation Time (VFT) is a novel index of systolic and diastolic function which may be also affected by left ventricular geometry, but has never been evaluated during dobutamine stress echocardiography (DSE) protocols. We sought to investigate the changes in VFT during DSE protocol.
Methods
DSE was performed in 50 consecutive patients. Patients with poor acoustic window, atrial fibrillation, cardiac valve disease or pacemaker were excluded. Apical four and apical two chamber views were acquired and the following parameters were calculated off- line without knowledge of DSE result both at rest and at peak: left ventricular end-diastolic and end-systolic volume, stroke volume, ejection fraction, stroke work, e and a wave peak velocity and VTI, TDI-derived mitral annular early diastolic velocity at the lateral wall and mitral valve diameter. VFT calculated according to the following equation: VFT = [4 *(1 − β) * α3 * EF]/π, where α = (LVEDV/α3)(1/3) and is affected by ventricular geometry and β = VTIa-wave/(VTIe wave + VTIa-wave) reflecting the atrial filling fraction.
Results
Median age of the study population was 61 [53–72], 38 men (76%) and 13 (26%) had an old myocardial infarction. Fifteen patients (30%) were positive for myocardial ischemia during DSE. At rest, median LVEDV was 121.5ml (101.8–148.0), median EF (%): 59.9 [54.4–64.1], median atrial filling fraction: 0.43 [0.40–0.48], median mitral valve diameter (cm): 2.8 [2.6–3.0] and median VFT: 2.44 [1.74–3.10]. At peak, median LVEDV was 102.0ml [86.4–122.3] median EF (%) 65.7 [58.8–69.8], median atrial filling fraction: 0.67 [0.59–0.73], median mitral valve diameter (cm): 2.7 [2.5–2.9] and median VFT: 1.45 [1.05–1.88]. VFT decreased in the whole population (Wilcoxon rank test, p<0.001) (figure 1A) and when patients were stratified according to test result. Median VFT decrease was significantly higher in patients with a positive DSE (50%) than in patients with negative DSE (39%) (Mann- Whitney U test, p=0.048) (figure 1B).
Figure 1
Conclusion
The VFT decreased significantly during DSE and most prominently in patients with ischemic response. This may indicate the deterioration of left ventricular diastolic or systolic function as well as change in left ventricular geometry during DSE protocol.
Vortex Formation Time Index in Patients With Hypertrophic Cardiomyopathy
