PMID- 21441312
OWN - NLM
STAT- MEDLINE
DCOM- 20110823
LR  - 20200930
IS  - 1522-1539 (Electronic)
IS  - 0363-6135 (Linking)
VI  - 300
IP  - 6
DP  - 2011 Jun
TI  - Modulated dispersion of activation and repolarization by premature beats in 
      patients with cardiomyopathy at risk of sudden death.
PG  - H2221-9
LID - 10.1152/ajpheart.01050.2010 [doi]
AB  - Premature beats can trigger ventricular arrhythmias in heart disease, but the 
      mechanisms are not well defined. We studied the effect of premature beats on 
      activation and repolarization dispersion in seven patients with cardiomyopathy 
      (57 +/- 10 yr, left ventricular ejection fraction 31 +/- 7%). Activation time (AT), 
      activation-recovery interval (ARI), and total repolarization time (TRT) were 
      measured from 26 unipolar electrograms during right ventricle (RV) endocardial 
      (early) to left ventricle epicardial (late) activation in response to RV apical 
      extrastimulation (S1S2). Early TRT dispersion increased significantly with 
      shorter S1S2 (1.0 +/- 0.2 to 2.3 +/- 0.4 ms/mm, P < 0.0001), with minimal change in 
      late TRT dispersion (0.8 +/- 0.1 to 1.0 +/- 0.3 ms, P = 0.02). This was associated 
      with an increase in early AT dispersion (1.0 +/- 0.1 to 1.5 +/- 0.2 ms/mm, P = 0.05) 
      but no change in late AT dispersion (0.6 +/- 0.1 to 0.7 +/- 0.2 ms/mm, P = 0.4). 
      Early and late ARI dispersion did not change with shorter S1S2. AT restitution 
      slopes were similar between early and late sites, as was slope heterogeneity. ARI 
      restitution slope was greater in early vs. late sites (1.3 +/- 0.6 vs. 0.8 +/- 0.6, P 
      = 0.03), but slope heterogeneity was similar. With shorter S1S2, AT-ARI slopes 
      became less negative (flattened) at both early (-0.4 +/- 0.1 to +0.04 +/- 0.2) and 
      late (-1.5 +/- 0.2 to +0.3 +/- 0.2) sites, implying less activation-repolarization 
      coupling. There was no difference in AT-ARI slopes between early and late sites 
      at short S1S2. In conclusion, high-risk patients with cardiomyopathy have greater 
      TRT dispersion at tightly coupled S1S2 due to greater AT dispersion and 
      activation-repolarization uncoupling. Modulated dispersion is more pronounced at 
      early vs. late activated sites, which may predispose to reentrant ventricular 
      arrhythmias.
FAU - Subramanian, Anandaraja
AU  - Subramanian A
AD  - PMCC 3-522, Toronto General Hospital, 150 Gerrard St. W., Toronto, ON M5G 2C4, 
      Canada.
FAU - Suszko, Adrian
AU  - Suszko A
FAU - Selvaraj, Raja J
AU  - Selvaraj RJ
FAU - Nanthakumar, Kumaraswamy
AU  - Nanthakumar K
FAU - Ivanov, Joan
AU  - Ivanov J
FAU - Chauhan, Vijay S
AU  - Chauhan VS
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20110325
PL  - United States
TA  - Am J Physiol Heart Circ Physiol
JT  - American journal of physiology. Heart and circulatory physiology
JID - 100901228
SB  - IM
MH  - Aged
MH  - Cardiac Complexes, Premature/*physiopathology
MH  - Cardiomyopathies/*physiopathology
MH  - Death, Sudden, Cardiac/*epidemiology
MH  - Electrocardiography
MH  - Electrophysiological Phenomena/physiology
MH  - Female
MH  - Heart Ventricles/physiopathology
MH  - Humans
MH  - Male
MH  - Middle Aged
MH  - Retrospective Studies
MH  - Risk Factors
MH  - Stroke Volume/physiology
MH  - Tachycardia, Ventricular/*physiopathology
EDAT- 2011/03/29 06:00
MHDA- 2011/08/24 06:00
CRDT- 2011/03/29 06:00
PHST- 2011/03/29 06:00 [entrez]
PHST- 2011/03/29 06:00 [pubmed]
PHST- 2011/08/24 06:00 [medline]
AID - ajpheart.01050.2010 [pii]
AID - 10.1152/ajpheart.01050.2010 [doi]
PST - ppublish
SO  - Am J Physiol Heart Circ Physiol. 2011 Jun;300(6):H2221-9. doi: 
      10.1152/ajpheart.01050.2010. Epub 2011 Mar 25.