title: Myocardial mechanics before and after ablation of chronic tachycardia.
abstract: Chronic tachycardia has been shown to cause a congestive cardiomyopathy; however, previous methods of evaluating ventricular function are highly dependent on cardiac loading conditions. Mean velocity of fiber shortening and its relation to end-systolic wall stress (ESS) is a preload independent index of contractility that incorporates afterload. We reviewed 33 patients (aged 5 months to 20 years; mean 9.7 years) with ectopic atrial tachycardia (EAT) (n = 19), permanent junctional reciprocating tachycardia (PJRT) (n = 12), or ventricular tachycardia (n = 2), who underwent nonpharmacological elimination of tachycardia ; 28 by radiofrequency ablation and 5 surgically. Ventricular function was evaluated by echocardiographic measurements of shortening fraction, mean velocity shortening corrected for heart rate (VcFc), and afterload as ESS. Contractility, expressed as the stress-velocity index, was determined by comparing the Ess/VcFc relation to the predicted normal VcFc for the measured ESS. Myocardial dysfunction was seen in 21 patients: 13 with EAT; 7 with PJRT; and 1 with ventricular tachycardia. In patients with EAT, the mean heart rate in tachycardia was significantly faster in those with dysfunction than in those without dysfunction (176.8 +/- 23.2 vs 136.7 +/- 28.2; P < 0.02). Of the 21 patients with dysfunction, full recovery was seen in 17 of 18 patients restudied after intervention (mean 17.5 +/- 17.6 weeks), and the remaining patient improved markedly, but did not normalize entirely. Dysfunction, seen in 64% of young patients with chronic tachycardia, was due to depressed myocardial contractility, and is generally reversible within 3 months of definitive therapy.
authors.affiliation: Department of Cardiology, Children's Hospital, Boston, Massachusetts, USA.
authors.forename: S B
authors.initials: SB
authors.lastname: Fishberger
authors.forename: S D
authors.initials: SD
authors.lastname: Colan
authors.forename: J P
authors.initials: JP
authors.lastname: Saul
authors.forename: J E
authors.initials: JE
authors.lastname: Mayer
authors.forename: E P
authors.initials: EP
authors.lastname: Walsh
mesh_terms: D002311:Cardiomyopathy, Dilated / Q000209:etiology / Q000503:physiopathology* / Q000517:prevention & control; D017115:Catheter Ablation; D002648:Child; D004452:Echocardiography; D005260:Female; D006801:Humans; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology*; D012189:Retrospective Studies; D013612:Tachycardia, Ectopic Atrial / Q000150:complications / Q000503:physiopathology* / Q000601:surgery; D013614:Tachycardia, Paroxysmal / Q000150:complications / Q000503:physiopathology* / Q000601:surgery; D017180:Tachycardia, Ventricular / Q000150:complications / Q000503:physiopathology* / Q000601:surgery; D013997:Time Factors; D018754:Ventricular Dysfunction / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology*; D016276:Ventricular Function / Q000502:physiology