X-ray of Implanted Cardioverter Defibrillator (ICD)
X-ray chest PA view showing the implanted cardioverter defibrillator and lead system. The device can is seen in the left pectoral region below the clavicle. Since it is a ‘hot’ can, meaning that it forms part of the defibrillation circuit, left pectoral position is ideal. This position gives better defibrillation thresholds than a right pectoral implant. This is because major portion of the left ventricular myocardium falls within the path of the defibrillation current which is delivered between the ‘hot can’ and the coils in the SVC and RV. The high voltage defibrillator coils are situated in the superior vena cava (SVC) and right ventricle (RV). The pacing electrodes are at the tip and just proximal to it near the RV apex. (Please increase the brightness setting of your monitor to see the leads in the picture well). Configuration of the defibrillation shock delivery between the electrodes can be programmed using the external programmer for the ICD. The leads will be better seen on image intensifier fluroscopy which will also permit the use of magnified views to detect incomplete lead fractures. Incomplete lead fracture can lead to inappropriate ICD discharge due to noise detected at the interface being misinterpreted as ventricular fibrillation. Lead fracture can also cause ineffective shock delivery and needs lead revision.