disease: differential effects in various anatomical and functional substrates Heart 2009;95(14):1165–1171 Heart failure associated with ventricular pacing is the largest indication for cardiac resynchronization therapy (CRT) in pediatric and congenital heart disease CRT efficacy varies widely with the underlying anatomical and pathophysiological substrate Dr Janousek reviews the mechanism by which CRT works and how to apply that knowledge to the patient with a systemic left ventricle, systemic right ventricle, or single-ventricle physiology Indik JH, et al 2017 HRS expert consensus statement on magnetic resonance imaging and radiation exposure in patients with cardiovascular implantable electronic devices Heart Rhythm 2017;14(7):e97–e153 Recently published and endorsed guidelines on magnetic resonance imaging in patients with cardiac implantable devices such as pacemakers This article focuses on physics behind magnetic resonance imaging and pacemakers as well as the importance of what type of device a patient currently has as well as other abandoned leads This is an article that should be reviewed by cardiology and radiology teams together References Romano M, et al Heart rate, PR, and QT intervals in normal children: a 24-hour Holter monitoring study Clin Cardiol 1988;11(12):839–842 Cohen MI, Rhodes LA Sinus node dysfunction and atrial tachycardia after the Fontan procedure: the scope of the problem Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu 1998;1:41–52 Bossers SS, et al Comprehensive rhythm evaluation in a large contemporary Fontan population Eur J Cardiothorac Surg 2015;48(6):833–840 [discussion 840-1] Janousek J, et al Atrial baffle procedures for complete transposition of the great arteries: natural course of sinus node dysfunction and risk factors for dysrhythmias and sudden death Z Kardiol 1994;83(12):933–938 Rychik J, et al Comparison of patterns of pulmonary venous blood flow in the functional single ventricle heart after operative aortopulmonary shunt versus superior cavopulmonary shunt Am J Cardiol 1997;80(7):922–926