Biventricular Pacemaker Malposition

Biventricular Pacemaker Dysfunction • Xray of the Week

Figure 1. Abnormal position of pacemaker.

Figure 2. CXR done 19 days after pacemaker placement. A- Note the retracted right atrial lead (green arrow) and right ventricular lead with shock coil (yellow arrow). The coronary sinus lead is also partially retracted (blue arrow). B- Coiled up electrodes adjacent to the generator (red arrow).

Figure 3. Immediate postoperative CXR obtained 19 days earlier demonstrating the correct position of the pacemaker. A- Note the correct position of the RA lead with the characteristic "J" shape (green arrow) as it curves superiorly and laterally with the tip in the right atrial appendage. The RV lead with shock coil has a gentle curve and the tip is at the RV apex (yellow arrow). The LV lead is also correctly positioned deep in the coronary sinus (blue arrow). B- Well positioned electrodes adjacent to the generator (red arrow).

Figure 4. Fluoroscopy images from the time of placement of the left ventricular/coronary sinus lead initially show contrast in the coronary sinus (orange arrows), followed by positioning of the lead in the coronary sinus (blue arrow).

Discussion:

Biventricular pacing also known as cardiac resynchronization therapy (CRT) is a modality of cardiac pacing used in congestive heart failure (CHF) patients with left ventricular (LV) systolic dysfunction and dys-synchronous ventricular activation. Biventricular pacemakers provide simultaneous or nearly simultaneous electrical activation of the LV and right ventricle (RV) via leads placed in the coronary sinus and the RV. As seen in this case, a right atrium (RA) lead is often present as well [1]. CRT has been shown to reduce heart failure hospitalization and/or mortality by up to 34% in patients with less advanced, predominantly NYHA class II heart failure patients [2].

CRT devices are inserted via the subclavian vein and are attached to a pulse generator unit which is then implanted subcutaneously, over the pectoralis muscle. Gentle loops of catheter into the heart and to the generator will avoid the problems of recoil from the ventricle or advancement into the pericardium. A snug pocket for the generator is desirable in order to avoid its motion with traction upon the catheter [3].

We are presenting a case where electrode dislodgement was caused by the patient twisting the pulse generator and coiling the electrode (red arrow- Image A & B) adjacent to the generator known as the “pacemaker twiddler’s syndrome” [4]. The tip of of the atrial lead (green arrow) is superior to level of right atrium and has come to rest in the superior vena cava (Figs. 1A,2A). The right ventricle lead (yellow arrow) and left ventricle lead (blue arrow) have also migrated proximally (Figs. 1A,2A).

Ventricular capture depends upon the intimate contact between the pacing electrode and the endocardium. Resistance to stimulation may occur with rise in threshold or loss of this contact due to dislodgement into the pericardium, pulmonary artery, right atrium or coronary sinus. Occasionally, malposition of the catheter will allow pacing to continue but at a higher current output, and premature failure of the pulse generator may occur.

Complications of pacemaker placement placement include lead migration, improper initial placement, and perforation. Migration of the RV lead across the tricuspid valve and into the inferior vena cava or migration into the LV via the interventricular septum or the interatrial septum may have catastrophic clinical results [3]. RV leads may rarely pass through a patent foramen ovale or perforate in the area near the fossa ovalis or pass through a persistent sinus venosus. Left ventricular pacing has also been reported due to inadvertent trans arterial placement, which allows the lead to cross the aortic valve and enter the left ventricular cavity [5]. Close abutment of the tip against the ventricle can lead to perforation of the myocardium and entrance of the catheter into the pericardial space leading to failure of ventricular capture or tamponade [3]. Malposition of a transvenous pacing lead into the left ventricle can cause thromboembolism. Other electrode associated complications include fracture, pneumothorax, hematoma (pocket or mediastinal), hardware infection, and inappropriate shocks [3, 6]. It is essential that lead position be correct and verified on frontal and lateral imaging before the placement procedure is terminated. A frontal projection alone cannot define appropriate lead position [3].

References:

1. Aguilera AL, Volokhina YV, Fisher KL. Radiography of cardiac conduction devices: a comprehensive review. Radiographics. 2011;31(6):1669-1682. doi:10.1148/rg.316115529

2. Zaręba W. Comparison of clinical trials evaluating cardiac resynchronization therapy in mild to moderate heart failure. Cardiol J. 2010;17(6):543-548. https://pubmed.ncbi.nlm.nih.gov/21154255/

3. McHenry, M.M. and C.E. Grayson, Roentgenographic Diagnosis of Pacemaker Failure. American Journal of Roentgenology, 1970. 109(1): p. 94-100 DOI: 10.2214/ajr.109.1.94. Retrieved from https://doi.org/10.2214/ajr.109.1.94

4. Tegtmeyer, C.J. and J.M. Deignan, The cardiac pacemaker: a different twist. AJR Am J Roentgenol, 1976. 126(5): p. 1017-8 DOI: 10.2214/ajr.126.5.1017

5. Bauersfeld, U.K., et al., Malposition of transvenous pacing lead in the left ventricle: radiographic findings. American Journal of Roentgenology, 1994. 162(2): p. 290-292 DOI: 10.2214/ajr.162.2.8310911

6. Costelloe, C.M., et al., Radiography of pacemakers and implantable cardioverter defibrillators. AJR Am J Roentgenol, 2012. 199(6): p. 1252-8 DOI: 10.2214/ajr.12.8641

Shama Jaswal is an International Medical Graduate, currently doing research at Mallinckrodt Institute of Radiology (MIR), Saint Louis. She aims at pursuing Diagnostic Radiology residency and poses a keen interest in research alongside academics. At MIR, she has been fortunate to work on various oncology projects including the project in which they studied how the difference in fat metabolism in both sexes can affect the cancer survival and outcome, and how this study can further improve prognosis through treatment modification. Shama is both an accomplished sprinter and singer having won several national competitions in in each discipline in India. She also has a strong passion for cooking and gardening.

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Kevin M. Rice, MD is the president of Global Radiology CME

Dr. Rice is a radiologist with Renaissance Imaging Medical Associates and is currently the Vice Chief of Staff at Valley Presbyterian Hospital in Los Angeles, California. Dr. Rice has made several media appearances as part of his ongoing commitment to public education. Dr. Rice's passion for state of the art radiology and teaching includes acting as a guest lecturer at UCLA. In 2015, Dr. Rice and Natalie Rice founded Global Radiology CME to provide innovative radiology education at exciting international destinations, with the world's foremost authorities in their field. In 2016, Dr. Rice was nominated and became a semifinalist for a "Minnie" Award for the Most Effective Radiology Educator.

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