title: Left ventricular diastolic filling with an implantable ventricular assist device: beat to beat variability with overall improvement.
abstract: OBJECTIVE
  We studied the effects of left ventricular (LV) unloading by an implantable ventricular assist device on LV diastolic filling.
  
  
  BACKGROUND
  Although many investigators have reported reliable systemic and peripheral circulatory support with implantable LV assist devices, little is known about their effect on cardiac performance.
  
  
  METHODS
  Peak velocities of early diastolic filling, late diastolic filling, late to early filling ratio, deceleration time of early filling, diastolic filling period and atrial filling fraction were measured by intraoperative transesophageal Doppler echocardiography before and after insertion of an LV assist device in eight patients. A numerical model was developed to simulate this situation.
  
  
  RESULTS
  Before device insertion, all patients showed either a restrictive or a monophasic transmitral flow pattern. After device insertion, transmitral flow showed rapid beat to beat variation in each patient, from abnormal relaxation to restrictive patterns. However, when the average values obtained from 10 consecutive beats were considered, overall filling was significantly normalized from baseline, with early filling velocity falling from 87 +/- 31 to 64 +/- 26 cm/s (p < 0.01) and late filling velocity rising from 8 +/- 11 to 32 +/- 23 cm/s (p < 0.05), resulting in an increase in the late to early filling ratio from 0.13 +/- 0.18 to 0.59 +/- 0.38 (p < 0.01) and a rise in the atrial filling fraction from 8 +/- 10% to 26 +/- 17% (p < 0.01). The deceleration time (from 112 +/- 40 to 160 +/- 44 ms, p < 0.05) and the filling period corrected by the RR interval (from 39 +/- 8% to 54 +/- 10%, p < 0.005) were also significantly prolonged. In the computer model, asynchronous LV assistance produced significant beat to beat variation in filling indexes, but overall a normalization of deceleration time as well as other variables.
  
  
  CONCLUSIONS
  With LV assistance, transmitral flow showed rapidly varying patterns beat by beat in each patient, but overall diastolic filling tended to normalize with an increase of atrial contribution to the filling. Because of the variable nature of the transmitral flow pattern with the assist device, the timing of the device cycle must be considered when inferring diastolic function from transmitral flow pattern.
authors.affiliation: Cardiovascular Imaging Center and Department of Cardiology, Cleveland Clinic Foundation, Ohio 44195, USA.
authors.forename: S
authors.initials: S
authors.lastname: Nakatani
authors.forename: J D
authors.initials: JD
authors.lastname: Thomas
authors.forename: P M
authors.initials: PM
authors.lastname: Vandervoort
authors.forename: J
authors.initials: J
authors.lastname: Zhou
authors.forename: N L
authors.initials: NL
authors.lastname: Greenberg
authors.forename: R M
authors.initials: RM
authors.lastname: Savage
authors.forename: P M
authors.initials: PM
authors.lastname: McCarthy
mesh_terms: D000328:Adult; D002311:Cardiomyopathy, Dilated / Q000150:complications; D003331:Coronary Vessels / Q000502:physiology; D015150:Echocardiography, Doppler; D017548:Echocardiography, Transesophageal; D005260:Female; D006333:Heart Failure / Q000209:etiology / Q000628:therapy*; D006353:Heart-Assist Devices; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000150:complications; D012039:Regional Blood Flow; D016277:Ventricular Function, Left