title: Disrupted right ventricular force-frequency relationships in adults operated for ventricular septal defect as toddlers: abnormal peak force predicts peak oxygen uptake during exercise.
abstract: Recent studies have shown markedly reduced functional capacity in long-term survivors of ventricular septal defect (VSD), and in order to explore possible mechanisms, we performed non-invasive assessment of ventricular force-frequency relationships during exercise in adults operated for VSD in early childhood. We conducted a prospective study at a tertiary referral center. Patients (n=23) and healthy controls (n=20) underwent continuous Doppler-echocardiographic imaging during supine bicycle ergometry. The cycling workload was individually and manually incremented during the test session in response to heart rate. The heart was imaged in an apical 4-chamber view, and color-coded myocardial velocities were recorded. Post hoc, peak systolic velocity and isovolumetric acceleration (IVA) were blindly determined in the basal ventricular segments. VSD-operated patients differed markedly in all right ventricular endpoints compared with controls. IVA was lower prior to the test, 70 ± 30 cm/s(2) vs. 150 ± 60 cm/s(2) among controls, and during the entire test session ending at a heart rate of 160 beats/min; 140 ± 50 cm/s(2) vs. 300 ± 30 cm/s(2), p < 0.01 at both points. A similar pattern was revealed in terms of peak right ventricular systolic velocity. Left ventricular and septal measurements showed a similar, although less significant, tendency with a clearly lower left ventricular optimum heart rate among patients: 140 beats/min vs. 154 beats/min among controls. In the diseased cohort biventricular force-frequency relationships were directly correlated to peak oxygen uptake. VSD repair in early childhood is associated with disruption of the right ventricular force-frequency relationship, which may contribute to the previously observed reduction in functional capacity.
authors.affiliation: Dept. of Cardiothoracic & Vascular Surgery, Aarhus University Hospital, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark. Electronic address: johan.heiberg@clin.au.dk.
authors.forename: Johan
authors.initials: J
authors.lastname: Heiberg
authors.affiliation: Dept. of Cardiology, Aarhus University Hospital, Brendstrupgaardsvej 100, 8200 Aarhus N, Aarhus, Denmark.
authors.forename: Michael Rahbek
authors.initials: MR
authors.lastname: Schmidt
authors.affiliation: Division of Cardiology, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada.
authors.forename: Andrew
authors.initials: A
authors.lastname: Redington
authors.affiliation: Dept. of Cardiothoracic & Vascular Surgery, Aarhus University Hospital, Brendstrupgaardsvej 100, 8200 Aarhus N, Denmark.
authors.forename: Vibeke Elisabeth
authors.initials: VE
authors.lastname: Hjortdal
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002675:Child, Preschool; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D005080:Exercise Test / Q000639:trends*; D005260:Female; D006345:Heart Septal Defects, Ventricular / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000601:surgery*; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D011237:Predictive Value of Tests; D011446:Prospective Studies; D014463:Ultrasonography; D018497:Ventricular Dysfunction, Right / Q000000981:diagnostic imaging* / Q000453:epidemiology; D055815:Young Adult
keywords: Congenital heart disease; Force–frequency response; Long-term follow-up; Ventricular septal defect