Enhanced transmural fiber rotation and connexin 43 heterogeneity are associated with an increased upper limit of vulnerability in a transgenic rabbit model of human hypertrophic cardiomyopathy

Crystal M Ripplinger, Wenwen Li, Jennifer Hadley, Junjie Chen, Florence Rothenberg, Raffaella Lombardi, Samuel A. Wickline, Ali J. Marian, Igor R. Efimov

Research output: Contribution to journalArticle

48 Citations (Scopus)

Abstract

Human hypertrophic cardiomyopathy, characterized by cardiac hypertrophy and myocyte disarray, is the most common cause of sudden cardiac death in the young. Hypertrophic cardiomyopathy is often caused by mutations in sarcomeric genes. We sought to determine arrhythmia propensity and underlying mechanisms contributing to arrhythmia in a transgenic (TG) rabbit model (β-myosin heavy chain-Q403) of human hypertrophic cardiomyopathy. Langendorff-perfused hearts from TG (n=6) and wild-type (WT) rabbits (n=6) were optically mapped. The upper and lower limits of vulnerability, action potential duration (APD) restitution, and conduction velocity were measured. The transmural fiber angle shift was determined using diffusion tensor MRI. The transmural distribution of connexin 43 was quantified with immunohistochemistry. The upper limit of vulnerability was significantly increased in TG versus WT hearts (13.3±2.1 versus 7.4±2.3 V/cm; P=3.2e), whereas the lower limits of vulnerability were similar. APD restitution, conduction velocities, and anisotropy were also similar. Left ventricular transmural fiber rotation was significantly higher in TG versus WT hearts (95.6±10.9° versus 79.2±7.8°; P=0.039). The connexin 43 density was significantly increased in the mid-myocardium of TG hearts compared with WT (5.46±2.44% versus 2.68±0.77%; P=0.024), and similar densities were observed in the endo- and epicardium. Because a nearly 2-fold increase in upper limit of vulnerability was observed in the TG hearts without significant changes in APD restitution, conduction velocity, or the anisotropy ratio, we conclude that structural remodeling may underlie the elevated upper limit of vulnerability in human hypertrophic cardiomyopathy.

Original languageEnglish (US)
Pages (from-to)1049-1057
Number of pages9
JournalCirculation Research
Volume101
Issue number10
DOIs
StatePublished - Nov 2007
Externally publishedYes

Fingerprint

Connexin 43
Hypertrophic Cardiomyopathy
Action Potentials
Rabbits
Anisotropy
Cardiac Arrhythmias
Endocardium
Diffusion Magnetic Resonance Imaging
Myosin Heavy Chains
Pericardium
Sudden Cardiac Death
Cardiomegaly
Cardiac Myocytes
Myocardium
Immunohistochemistry
Mutation
Genes

Keywords

  • Arrhythmia
  • Hypertrophic cardiomyopathy
  • Transgenic rabbit
  • Vulnerability

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

Cite this

Enhanced transmural fiber rotation and connexin 43 heterogeneity are associated with an increased upper limit of vulnerability in a transgenic rabbit model of human hypertrophic cardiomyopathy. / Ripplinger, Crystal M; Li, Wenwen; Hadley, Jennifer; Chen, Junjie; Rothenberg, Florence; Lombardi, Raffaella; Wickline, Samuel A.; Marian, Ali J.; Efimov, Igor R.

In: Circulation Research, Vol. 101, No. 10, 11.2007, p. 1049-1057.

Research output: Contribution to journalArticle

Ripplinger, Crystal M ; Li, Wenwen ; Hadley, Jennifer ; Chen, Junjie ; Rothenberg, Florence ; Lombardi, Raffaella ; Wickline, Samuel A. ; Marian, Ali J. ; Efimov, Igor R. / Enhanced transmural fiber rotation and connexin 43 heterogeneity are associated with an increased upper limit of vulnerability in a transgenic rabbit model of human hypertrophic cardiomyopathy. In: Circulation Research. 2007 ; Vol. 101, No. 10. pp. 1049-1057.
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AU - Ripplinger, Crystal M

AU - Li, Wenwen

AU - Hadley, Jennifer

AU - Chen, Junjie

AU - Rothenberg, Florence

AU - Lombardi, Raffaella

AU - Wickline, Samuel A.

AU - Marian, Ali J.

AU - Efimov, Igor R.

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AB - Human hypertrophic cardiomyopathy, characterized by cardiac hypertrophy and myocyte disarray, is the most common cause of sudden cardiac death in the young. Hypertrophic cardiomyopathy is often caused by mutations in sarcomeric genes. We sought to determine arrhythmia propensity and underlying mechanisms contributing to arrhythmia in a transgenic (TG) rabbit model (β-myosin heavy chain-Q403) of human hypertrophic cardiomyopathy. Langendorff-perfused hearts from TG (n=6) and wild-type (WT) rabbits (n=6) were optically mapped. The upper and lower limits of vulnerability, action potential duration (APD) restitution, and conduction velocity were measured. The transmural fiber angle shift was determined using diffusion tensor MRI. The transmural distribution of connexin 43 was quantified with immunohistochemistry. The upper limit of vulnerability was significantly increased in TG versus WT hearts (13.3±2.1 versus 7.4±2.3 V/cm; P=3.2e), whereas the lower limits of vulnerability were similar. APD restitution, conduction velocities, and anisotropy were also similar. Left ventricular transmural fiber rotation was significantly higher in TG versus WT hearts (95.6±10.9° versus 79.2±7.8°; P=0.039). The connexin 43 density was significantly increased in the mid-myocardium of TG hearts compared with WT (5.46±2.44% versus 2.68±0.77%; P=0.024), and similar densities were observed in the endo- and epicardium. Because a nearly 2-fold increase in upper limit of vulnerability was observed in the TG hearts without significant changes in APD restitution, conduction velocity, or the anisotropy ratio, we conclude that structural remodeling may underlie the elevated upper limit of vulnerability in human hypertrophic cardiomyopathy.

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KW - Vulnerability

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