title: Left ventricular fluid dynamics in heart failure: echocardiographic measurement and utilities of vortex formation time.
abstract: BACKGROUND
  In clinical heart failure (HF), inefficient propagation of blood through the left ventricle (LV) may result from suboptimal vortex formation (VF) ability of the LV during early diastole. We aim to (i) validate echocardiographic-derived vortex formation time (adapted) (VFTa) in control subjects and (ii) examine its utility in both systolic and diastolic HF.
  
  
  METHODS
  Transthoracic echocardiography was performed in 32 normal subjects and in 130 patients who were hospitalized with HF [91, reduced ejection fraction (rEF) and 39, preserved ejection fraction (pEF)]. In addition to biplane left ventricular ejection fraction (LVEF) and conventional parameters, the Tei index and tissue Doppler (TD) indices were measured. VFTa was obtained using the formula: 4 × (1 - β)/π × α³ × LVEF, 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 the biplane end-diastolic volume (EDV)(1/3) divided by mitral annular diameter during early diastole. VFTa was correlated with demographic, cardiac parameters, and a composite clinical endpoint comprising cardiac death and repeat hospitalization for HF.
  
  
  RESULTS
  Mean VFTa was 2.67 ± 0.8 in control subjects; reduced in HF, preserved EF HF, 2.21 ± 0.8; HF with reduced EF, 1.25 ± 0.6 (P< 0.001). It was not affected by age, gender, body surface area but was correlated positively with TD early diastolic myocardial velocities (E', septal, r = 0.46; lateral, r = 0.43), systolic myocardial velocities (S', septal, r = 0.47; lateral, r = 0.41), and inversely with the Tei index (r = -0.41); all Ps < 0.001. Sixty-two HF patients (49%) met the composite endpoint. VFTa of <1.32 was associated with significantly reduced event-free survival (Kaplan Meier log rank = 16.3, P= 0.0001) and predicted the endpoint with a sensitivity and specificity of 65 and 72%, respectively.
  
  
  CONCLUSIONS
  VFTa, a dimensionless index, incorporating LV geometry, systolic and diastolic parameters, may be useful in the diagnosis and prognosis of HF.
authors.affiliation: Cardiac Department, National University Heart Center, 1E, Kent Ridge Road, NUHS Tower Block, Level 9, Singapore 119228, Singapore. doctorpoh@yahoo.com
authors.forename: Kian Keong
authors.initials: KK
authors.lastname: Poh
authors.forename: Li Ching
authors.initials: LC
authors.lastname: Lee
authors.forename: Liang
authors.initials: L
authors.lastname: Shen
authors.forename: Eric
authors.initials: E
authors.lastname: Chong
authors.forename: Yee Leng
authors.initials: YL
authors.lastname: Tan
authors.forename: Ping
authors.initials: P
authors.lastname: Chai
authors.forename: Tiong Cheng
authors.initials: TC
authors.lastname: Yeo
authors.forename: Malissa J
authors.initials: MJ
authors.lastname: Wood
mesh_terms: D000367:Age Factors; D000368:Aged; D000704:Analysis of Variance; D016009:Chi-Square Distribution; D016001:Confidence Intervals; D003971:Diastole; D004452:Echocardiography / Q000295:instrumentation*; D005260:Female; D006305:Health Status Indicators; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000473:pathology*; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000473:pathology*; D006439:Hemodynamics; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D009206:Myocardium; D011237:Predictive Value of Tests; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D013318:Stroke Volume; D013599:Systole; D013997:Time Factors; D016277:Ventricular Function, Left