Tanzania Medical Students Association

IR case of the month

TAMSA IR CASE # 3

Patient details and symptoms:

75 year old male is day 1 post-op after insertion of a permanent single lead pacemaker for persistent symptomatic bradycardia. 

Below is a routine post-operative portable radiograph of the chest for this patient: 

 

 

An area of increased density is noted in the left shoulder, possibly extending into the left lung apex and crossing over the pacemaker lead.  

The following image is an example of an unremarkable chest radiograph containing a single-lead pacemaker: 

Source: https://pubs.rsna.org/na101/home/literatum/publisher/rsna/journals/content/radiographics/2011/radiographics.2011.31.issue-6/rg.316115529/20141103/images/medium/115529fig02a.jpeg

Physical examination: 

vital signs:  within normal limits 

cardiovascular: 

-radial pulse is regular in rate and rhythm

            -S1S2 heart sounds are appreciated on auscultation, with no murmurs or extra sounds  

respiratory:

            -lungs clear to auscultation, with good air entry appreciated bilaterally

            -no evidence of respiratory distress or increased work of breathing 

Laboratory investigations return and there are no abnormalities. 

During a routine dressing change, you notice the gauze looks as follows: 

Diagnosis: Metal artifact from the type of gauze used to cover the patient’s wound. 

Discussion:

A pacemaker is a device designed to stimulate cardiac contraction through the delivery of an electrical stimulus. These electrical stimuli are released when a patient’s heart rate is too low, making it essential in the treatment of persistent symptomatic bradycardia. Modern pacemakers are also able to treat atrial fibrillation and atrial flutter. There are dual and single lead pacemakers. Single leads can be placed in either the right atrium or right ventricle, with the most common location for placement being in the apex of the right ventricle.  

Pacemakers monitor a patient’s cardiac rhythm by sensing electrical impulses between the anode and cathode (electrodes) of the device. There are unipolar and bipolar leads. Bipolar leads have the electrodes at their tips, whereas in unipolar pacing, the generator serves as the anode. Bipolar leads are more common, as they are more versatile and carry less risk of erroneously stimulating the chest wall or diaphragm when compared to its unipolar counterparts. 

The most common indications for pacemaker insertion are sinus node dysfunction and high-grade AV block. Other indications are as follows: 

-chronic bifascicular block

-post myocardial infarction

-neurocardiogenic syncope

-hypersensitive carotid sinus syndrome

-post cardiac transplantation

-hypertrophic cardiomyopathy

-cardiac resynchronization therapy in cases of severe systolic heart failure

-congenital heart disease

Complications can be categorized temporally based on whether they are acute or chronic. 

Acute complications tend to occur very shortly after insertion. They include improper placement or pacing of the leads (which can lead to arrhythmia), pneumothorax, hemothorax, perforation of the myocardium or surrounding great vessels, improper configuration of the generator, and infection. Another acute complication, which is more common in single lead devices, is something called dry pocket, in which air leaks into the surrounding subcutaneous tissue. This can lead to issues with the conduction of the electrical impulses. 

Chronic complications tend to stem from general wear and tear caused by aging of the device. Some examples include lead fracture, damage to lead insulation, lead displacement and Twiddler syndrome. Lead fractures commonly occur where the subclavian vein passes under the clavicle; this is referred to as subclavian crush syndrome.

Although some pacemaker issues are not identifiable on imaging, numerous are and chest radiography remains essential in evaluation of CCDs. For instance, chest x-rays can give important information to clinicians, such as the manufacturer of the generator, lead number, type, and configuration, as well as whether a CCD is MRI compatible. 

Source: https://www.ajronline.org/na101/home/literatum/publisher/arrs/journals/content/ajr/2012/ajr.2012.199.issue-6/ajr.12.8641/production/images/small/12_12_8641_01b_cmyk.gif

Take home point:Although it is important to be vigilant for pacemaker complications, it can be beneficial to take a step back and place radiographic findings in the context of the patient. For all intents and purposes, this patient was clinically well, making an acute complication less likely. This case is an example of an Aunt Minnie.  Surgical gauze is often impregnated with some kind of metallic marker in order to facilitate identification of retained sponges in the surgical (or IR) suites.  In this case, the area of increased density was due to artifact from a gauze dressing that contained metal. 

Sources: 

1)      Aguilera, A. L., Fisher, K. L., Volokhina, Y. V. (2011). Radiography of Cardiac Conduction Devices: a Comprehensive Review https://doi.org/10.1148/rg.316115529  

2)     Costelloe, C. M., Murphy, W. A. Jr., Gladish, G. W., Rozner, M. A. (2012). Radiography of Pacemakers and Implantable Cardioverter Defribrillators. American Journal of Roentgenology199:6, 1252-1258

3)     Dalia T, Amr BS. Pacemaker Indications. [Updated 2019 Jun 16]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507823/

4)     Dipoce, J., Bernheim, A., & Spindola-Franco, H. (2015). Radiology of cardiac devices and their complications. The British journal of radiology88(1046), 20140540. doi:10.1259/bjr.20140540

 

Submitted by: Matthew Stewart, BHS, RTR, MD Candidate, class of 2020 at Dalhousie UniversityFebruary 13, 2020

Edits provided by: Dr. Murray Asch, MD, FRCPC, FSIR, Toronto, Canada 

Posted by: Nancy Kaur, Medical Student, Munich, Germany 

Acknowledgements:Members of TAMSA 

 

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