Author + information
Heart transplant recipients (HTR) have reduced peak oxygen consumption (VO2) associated with impaired heart rate response and LV diastolic dysfunction. Left atrial function is a recognized modulator of cardiac output, especially in diastolic dysfunction. We aim to study the atrial-ventricular interaction in HTR using speckle tracking echocardiography during baseline and reduced preload stress to understand its relationship to VO2.
Eight HTR and 8 age & sex matched controls (15yr ± 5) had echocardiography in supine and 30 degrees head-up tilt. Left atrial strain and strain rate (SR), LV strain and SR, and LV twist were measured in both positions. Left atrial deformation zero was referenced to the beginning of the ECG p-wave to obtain active, conduit, reservoir strain and SR. All subjects then underwent exercise testing for peak VO2.
At supine, HTR atrial active and reservoir, strain and SR, as well as LV strain, were reduced compared to controls. Head up tilt was effective in reducing preload in both groups, reducing LVEDV and LA maximal volume. The controls LV response to preload reduction include a mild reduction in peak LV strain and increased peak LV twist and twist rate, as well as reduction in atrial reservoir strain with no increase in atrial active to reservoir strain ratio (0.30 vs. 0.27, p=0.45). In contrast, HTR showed no increase in LV twist but has a trend towards increased atrial active to reservoir strain ratio (0.27 vs. 0.37, p =0.06). HTR Peak VO2 was impaired (p<0.01) with a trend to having a lower peak heart rate (p=0.06). During head up tilt, HTR peak VO2 correlated strongly with peak heart rate (r=0.79, p=0.03), ?active (r=0.81, p=0.01) and active to reservoir strain ratio (r=-0.88, p=0.007), whilst controls did not.
During preload reduction stress, HTR appears to have impaired LV twist compensation and a trend towards increased reliance on active atrial function for ventricular filling. HTR with a greater reliance on atrial active function correlated strongly with poorer exercise tolerance. Left atrial deformation assessment during preload reduction stress may be a useful tool in the investigation of early LV diastolic dysfunction in HTR.
Poster Sessions, Expo North
Sunday, March 10, 2013, 9:45 a.m.-10:30 a.m.
Session Title: Imaging: Echo: Atrial Imaging
Abstract Category: 18. Imaging: Echo
Presentation Number: 1226-334
- 2013 American College of Cardiology Foundation