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Acute Pulmonary Embolism Presenting as Inappropriate Shock in a Patient With Externalized ICD Lead FREE TO VIEW

Satish Chandraprakasam, MD; Janardhana Gorthi, MD; Claire Hunter, MD; Kelly Airey, MD
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Creighton University Medical Center, Omaha, NE

Chest. 2013;144(4_MeetingAbstracts):316A. doi:10.1378/chest.1701305
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SESSION TITLE: Cardiovascular Critical Care

SESSION TYPE: Medical Student/Resident Case Report

PRESENTED ON: Sunday, October 27, 2013 at 10:45 AM - 11:45 AM

INTRODUCTION: The clinical utility and safety of implantable cardioverter defibrillator (ICD) has been well established. Lead thrombosis and pulmonary embolism are rare complications of lead externalization.

CASE PRESENTATION: A 79 year old female with history of non-ischemic cardiomyopathy status post implantable cardioverter defibrillator (ICD) implantation was admitted for evaluation of a large right atrial mass detected by echocardiogram ordered for asymptomatic murmur. Examination revealed a holosystolic murmur in the left lower sternal border. Fluoroscopy revealed an inside-out abrasion with an externalized lead starting at the right atrium (RA) and ending proximal to right ventricle (RV) coil. Intracardiac echocardiogram (ICE) revealed a mobile homogenous bi-lobed mass measuring 4.3x1.6 cm, consistent with thrombus attached to ICD lead and the right atrial wall (image 1). She was treated with unfractionated heparin and warfarin. She remained asymptomatic and was discharged to home on warfarin with a goal international normalized ratio (INR) between 2.5 and 3. Four weeks later, she was readmitted with shortness of breath and palpitations followed by multiple ICD shocks. INR was 2.2 at admission. ICD interrogation revealed 7 inappropriate shocks delivered for what appeared to be atrial tachycardia (AT) with variable atrio ventricular (AV) intervals and a ventricular rate of 150 bpm. Due to the variability of AV interval during AT, the AV interval discriminator declared the tachyarrhythmia as ventricular tachycardia (VT) and hence inappropriate ICD shock was delivered. Computed tomogram (CT) angiogram of chest revealed a filling defect in the proximal branch of left pulmonary artery suggestive of acute pulmonary embolism (PE) (image 2). The patient’s age, clot burden and lead characteristics including externalization, made her a high risk surgical candidate. Upon discharge, she was advised close follow up with her physicians to monitor the lead thrombus and maintain INR between 2.5 and 3.

DISCUSSION: Lead externalization is characterized by conductor wires projecting from the lead body. Despite the ethylene tetrafluoroethylene (ETFE) coating, the externalized lead is highly thrombogenic as a result of myocardial tissue irritation. Acute PE occurred secondary to spontaneous clot dislodgement from lead thrombus despite therapeutic anticoagulation which is explained by clot burden. Atrial tachycardia was precipitated by acute PE leading to inappropriate ICD shock. Lead extraction is extremely complex because of high surgical morbidity and mortality rates.

CONCLUSIONS: Acute PE is a rare but serious complication of externalized ICD leads. In unusual cases, it can further complicate management by causing arrhythmias leading to inappropriate shocks.

Reference #1: Coleman DB, DeBarr DM,Morales DL,Spotnitz HM. Pacemaker lead thrombosis treated with atrial thrombectomy and biventricular pacemaker and defibrillator insertion. Ann Thorac Surg. 2004 Nov;78(5):e83-4.

DISCLOSURE: The following authors have nothing to disclose: Satish Chandraprakasam, Janardhana Gorthi, Claire Hunter, Kelly Airey

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