title: Association of myotonic dystrophy and sick sinus syndrome, with special reference to electrophysiological and histological examinations.
abstract: Sick sinus syndrome is a rare but potentially important cardiac disorder in patients with myotonic dystrophy. We evaluated 3 patients with myotonic dystrophy complicated with sick sinus syndrome using intracardiac electrocardiography and endomyocardial biopsy. Electrocardiography identified sinus arrest, atrial flutter and right bundle-branch block in 2 cases and marked sinus bradycardia and first-degree atrioventricular block in 1 case. Their sinus node recovery times were significantly prolonged as demonstrated by the overdrive suppression test. Two patients had Adams-Stokes syndrome and one had tachycardia with severe palpitations. Therefore permanent pacemaker implantation was indicated in all 3 cases. Light microscopic analysis of right ventricular endomyocardial biopsies showed vacuolar degeneration and nuclear deformity of cardiomyocytes in all cases and endocardial and interstitial fibrosis in 1 case. These findings indicate that pathological changes may occur in any part of the myocardium in patients with myotonic dystrophy.
authors.affiliation: Second Department of Internal Medicine, Iwate Medical University School of Medicine.
authors.forename: I
authors.initials: I
authors.lastname: Segawa
authors.forename: M
authors.initials: M
authors.lastname: Kikuchi
authors.forename: A
authors.initials: A
authors.lastname: Tashiro
authors.forename: K
authors.initials: K
authors.lastname: Hiramori
authors.forename: M
authors.initials: M
authors.lastname: Sato
authors.forename: R
authors.initials: R
authors.lastname: Satodate
mesh_terms: D000328:Adult; D001706:Biopsy / Q000379:methods; D006328:Cardiac Catheterization; D004562:Electrocardiography; D004699:Endocardium / Q000473:pathology*; D005260:Female; D005355:Fibrosis / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009223:Myotonic Dystrophy / Q000150:complications* / Q000473:pathology* / Q000503:physiopathology; D011669:Pulmonary Wedge Pressure; D012804:Sick Sinus Syndrome / Q000209:etiology* / Q000473:pathology* / Q000503:physiopathology