Electrophysiologic characterization and postnatal development of ventricular pre-excitation in a mouse model of cardiac hypertrophy and Wolff-Parkinson-White syndrome.

Abstract

OBJECTIVES:

We sought to characterize an animal model of the Wolff-Parkinson-White (WPW) syndrome to help elucidate the mechanisms of accessory pathway formation.

BACKGROUND:

Patients with mutations in PRKAG2 manifest cardiac hypertrophy and ventricular pre-excitation; however, the mechanisms underlying the development and conduction of accessory pathways remain unknown.

METHODS:

We created transgenic mice overexpressing either the Asn488Ile mutant (TG(N488I)) or wild-type (TG(WT)) human PRKAG2 complementary deoxyribonucleic acid under a cardiac-specific promoter. Both groups of transgenic mice underwent intracardiac electrophysiologic, electrocardiographic (ECG), and histologic analyses.

RESULTS:

On the ECG, approximately 50% of TG(N488I) mice displayed sinus bradycardia and features suggestive of pre-excitation, not seen in TG(WT) mice. The electrophysiologic studies revealed a distinct atrioventricular (AV) connection apart from the AV node, using programmed stimulation. In TG(N488I) mice with pre-excitation, procainamide blocked bypass tract conduction, whereas adenosine infusion caused AV block in TG(WT) mice but not TG(N488I) mice with pre-excitation. Serial ECGs in 16 mice pups revealed no differences at birth. After one week, two of eight TG(N488I) pups had ECG features of pre-excitation, increasing to seven of eight pups by week 4. By nine weeks, one TG(N488I) mouse with WPW syndrome lost this phenotype, whereas TG(WT) pups never developed pre-excitation. Histologic investigation revealed postnatal development of myocardial connections through the annulus fibrosum of the AV valves in young TG(N488I) but not TG(WT) mice.

CONCLUSIONS:

Transgenic mice overexpressing the Asn488Ile PRKAG2 mutation recapitulate an electrophysiologic phenotype similar to humans with this mutation. This includes procainamide-sensitive, adenosine-resistant accessory pathways induced in postnatal life that may rarely disappear later in life.

• Authors: Vickas V Patel, Michael Arad, Ivan P G Moskowitz, Colin T Maguire, Dorothy Branco, J G Seidman, Christine E Seidman, Charles I Berul
• Journal: Journal of the American College of Cardiology (J Am Coll Cardiol) Vol. 42 Issue 5 Pg. 942-51 (Sep 03 2003) ISSN: 0735-1097 [Print] United States
• PMID: 12957447 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anti-Arrhythmia Agents
• Multienzyme Complexes
• Protein Serine-Threonine Kinases
• AMP-Activated Protein Kinases
• Adenosine
• Procainamide

Topics

• AMP-Activated Protein Kinases
• Adenosine
• Age Factors
• Animals
• Anti-Arrhythmia Agents
• Biopsy
• Cardiomegaly (complications, genetics, pathology)
• Disease Models, Animal
• Disease Progression
• Electrocardiography
• Electrophysiologic Techniques, Cardiac (methods)
• Electrophysiology
• Genotype
• Heart Conduction System
• Mice
• Mice, Transgenic
• Multienzyme Complexes (genetics)
• Mutation, Missense (genetics)
• Phenotype
• Pre-Excitation Syndromes (diagnosis, genetics)
• Procainamide
• Protein Serine-Threonine Kinases (genetics)
• Single-Blind Method
• Ventricular Dysfunction (diagnosis, genetics)
• Wolff-Parkinson-White Syndrome (complications, genetics, pathology)