Magnetic Resonance-Augmented Cardiopulmonary Exercise Testing: Comprehensively Assessing Exercise Intolerance in Children With Cardiovascular Disease

Circ Cardiovasc Imaging. 2016 Dec;9(12):e005282. doi: 10.1161/CIRCIMAGING.116.005282.

Abstract

Background: Conventional cardiopulmonary exercise testing can objectively measure exercise intolerance but cannot provide comprehensive evaluation of physiology. This requires additional assessment of cardiac output and arteriovenous oxygen content difference. We developed magnetic resonance (MR)-augmented cardiopulmonary exercise testing to achieve this goal and assessed children with right heart disease.

Methods and results: Healthy controls (n=10) and children with pulmonary arterial hypertension (PAH; n=10) and repaired tetralogy of Fallot (n=10) underwent MR-augmented cardiopulmonary exercise testing. All exercises were performed on an MR-compatible ergometer, and oxygen uptake was continuously acquired using a modified metabolic cart. Simultaneous cardiac output was measured using a real-time MR flow sequence and combined with oxygen uptake to calculate arteriovenous oxygen content difference. Peak oxygen uptake was significantly lower in the PAH group (12.6±1.31 mL/kg per minute; P=0.01) and trended toward lower in the tetralogy of Fallot group (13.5±1.29 mL/kg per minute; P=0.06) compared with controls (16.7±1.37 mL/kg per minute). Although tetralogy of Fallot patients had the largest increase in cardiac output, they had lower resting (3±1.2 L/min per m2) and peak (5.3±1.2 L/min per m2) values compared with controls (resting 4.3±1.2 L/min per m2 and peak 6.6±1.2 L/min per m2) and PAH patients (resting 4.5±1.1 L/min per m2 and peak 5.9±1.1 L/min per m2). Both the PAH and tetralogy of Fallot patients had blunted exercise-induced increases in arteriovenous oxygen content difference. However, only the PAH patients had significantly reduced peak values (6.9±1.3 mlO2/100 mL) compared with controls (8.4±1.4 mlO2/100 mL; P=0.005).

Conclusions: MR-augmented cardiopulmonary exercise testing is feasible in both healthy children and children with cardiac disease. Using this novel technique, we have demonstrated abnormal exercise patterns in oxygen uptake, cardiac output, and arteriovenous oxygen content difference.

Keywords: cardiovascular magnetic resonance imaging; exercise physiology; pediatric; pulmonary hypertension; tetralogy of Fallot.

Publication types

  • Evaluation Study

MeSH terms

  • Adolescent
  • Age Factors
  • Cardiac Output
  • Cardiac Surgical Procedures / adverse effects
  • Cardiorespiratory Fitness*
  • Case-Control Studies
  • Child
  • Exercise Test / methods*
  • Exercise Tolerance*
  • Feasibility Studies
  • Female
  • Health Status
  • Humans
  • Hypertension, Pulmonary / diagnostic imaging*
  • Hypertension, Pulmonary / physiopathology
  • Magnetic Resonance Imaging*
  • Male
  • Observer Variation
  • Oxygen Consumption
  • Predictive Value of Tests
  • Pulmonary Valve Insufficiency / diagnostic imaging*
  • Pulmonary Valve Insufficiency / etiology
  • Pulmonary Valve Insufficiency / physiopathology
  • Reproducibility of Results
  • Stroke Volume
  • Tetralogy of Fallot / surgery*
  • Ventricular Function, Left
  • Ventricular Function, Right