Pacing in Patients with Structural Cardiac Abnormalities

Abstract

Although most adult patients requiring pacemaker or ICD implantation will have normal cardiac anatomy, occasionally significant abnormalities will be found only at the time of the procedure, since they had not given rise to symptoms or any obvious physical signs. These include persistent left-sided superior vena cava (SVC) (with or without a right-sided SVC), dextrocardia, atrial septal defect, and patent foramen ovale. Such abnormalities may give rise to practical problems during lead placement and operators should be aware to recognize the problem immediately and know how to deal with it. Patients (adults or children) with congenital structural cardiac abnormalities, such as transposition, corrected transposition, tetralogy of Fallot, univentricular heart, or post-operative “corrected” defects, will require special consideration before proceeding to the pacing theater. In particular, the operator will need to know whether the transvenous approach is feasible, what problems might be encountered during lead implantation, and how to seek the best and most stable of electrode positions. Preoperative investigations, including transthoracic and transesophageal echocardiography, CT and MRI cardiac imaging as well as angiography, for example, left arm venography, should be used to clarify the cardiac and venous anatomy in order to safely embark on transvenous lead placements. Simply reviewing previous surgical notes (following cardiac surgery in earlier life) or previous cardiac catheterization notes may be useful in noting anatomical abnormalities. In recent times with the advent of biventricular pacing, it is relevant also to know the position of the coronary sinus, for example in patients with Ebstein anomaly who have already undergone tricuspid valve replacement.