A 78 year-old man with a history of paroxysmal atrial fibrillation (AF) presented with syncope and underwent implantation of a dual-chamber Medtronic KDR703 pacemaker while in AF. A Medtronic 4068 ventricular lead was implanted and found to have a threshold of 1.2 Volts (V) at 0.5 ms, a current of 1.8 milliamps and an impedance of 887 ohms. R-wave sensing was noted to be 16.6 mV. A Medtronic 4568 atrial lead was implanted but threshold testing was not performed and sensing was not reported. The pacemaker was programmed to VVIR 60-120.\nTwo months later, the patient developed left upper extremity weakness and a computed-tomography (CT) scan confirmed the clinical diagnosis of a right parietal cerebrovascular accident (CVA). The CVA was attributed to thromboembolism secondary to AF and the patient was initiated on warfarin therapy with a target INR of 2.0-3.0.\nThe patient was referred to our clinic after his ventricular lead was noted to have low impedance and a decrease in sensed R wave amplitude on routine interrogation. The patient's ECG is shown (). The diagnosis of inappropriate lead placement in the LV was suspected on the basis of the paced right bundle branch block (RBBB) pattern noted on this ECG. The diagnosis was confirmed by anterior and lateral chest radiography (). A non-contrast chest CT scan shows the ventricular lead coursing from the right atrium into the left atrium (LA) through an atrial septum defect (ASD) ().\nDevice interrogation revealed a ventricular lead threshold of 1.25 V at 0.4 ms, R wave sensing of 2.8-4.0 mV and a lead impedence of 248 ohms. The patient was in AF during interrogation with a slow, irregular ventricular response. No atrial capture could be demonstrated and no P waves were sensed.\nDue to suspected ventricular lead dysfunction and concern that sudden loss of ventricular pacing would lead to a recurrence of syncope, the patient underwent lead revision. A St. Jude 1688 lead was inserted into the right ventricle under fluoroscopic guidance using anterior and lateral views and the existing atrial lead and LV lead were capped. The patient's warfarin dose was increased to achieve a target INR of 2.5-3.5. The patient was discharged home without event. At the time of this report submission, the patient has had no further TE complications. Given the patient's age and comorbidities, should he experience further TE complications despite appropriate anticoagulation or if he develops an absolute contraindication to warfarin, we would consider percutaneous LV lead extraction with on-site cardiothoracic surgery back-up.
A 23-year-old female with Ebstein's anomaly of tricuspid valve underwent one and half ventricular repair with tricuspid valve annuloplasty, atrial septal defect closure and cavopulmonary anastamosis of right superior venacava to the right pulmonary artery. She also needed dual chamber pacing for symptomatic bradycardia secondary to sinus nodal and atrioventricular nodal disease. There was no pre-excitation or tachyarrhythmias. Left atrial and left ventricular epicardial leads were connected to a pulse generator that was implanted in epigastric subcutaneous pocket. There was synchronous atrioventricular pacing with acceptable pacing thresholds during the time of implantation. Three months later, new onset symptomatic diaphragmatic pacing was observed from atrial lead. So the pacemaker was reprogrammed to pace ventricle alone. After another two months, diaphragmatic pacing was observed from ventricular lead too. The threshold voltage for ventricular capture was more than that of the diaphragm. The reasons for delayed onset diaphragmatic pacing through both leads almost five months after the epicardial lead placement and pacemaker implantation was not understood. Her symptoms related to bradycardia warranted permanent dual chamber pacing. Since extensive dissections will be needed through the previous surgical scars and adhesions in midline sternotomy and left thoracotomy, a second epicardial lead repositioning was not considered. A minimal incision right anterolateral thoracotomy was made and two introducer sheaths were inserted through two pursestring sutures placed on the right atrial free wall.() Two screw-in endocardial leads were inserted through the sheaths under transesophageal echocardiographic guidance into the right atrial appendage tip and right ventricular apex to achieve atrioventricular pacing. On a follow up of nine months, the patient was asymptomatic, pacing was synchronous and chest X-ray showed both the new and old leads. ()