A rare case of sinus venosus atrial septal defect: Malpositioned right atrial pacemaker lead in the left atrium

Abstract

Incidental discovery of sinus venosus atrial septal defect (SV-ASD) in the elderly is rare. This defect allows for lead malpositioning during pacemaker placement and can lead to catastrophic cardioembolic events. Post-pacemaker implantation, chest radiography should be obtained to detect malpositioning early, and if detected, lead adjustment is recommended; if identified later, treatment with an anticoagulant is feasible. SV-ASD repair may be considered as well.

Learning objective

• 1.To raise awareness of clinicians on the rare presentation of sinus venosus atrial septal defect, and diagnostic tools available to recognize the defect.
• 2.To understand the management of malpositioned pacemaker lead in individuals with interatrial shunt.

Introduction

In SV-ASD there is an interatrial connection caused by the lack of a common wall between superior vena cava and pulmonary veins. This interatrial connection can allow for inadvertent lead malpositioning. There are numerous complications associated with such malposition, including damage to mitral and aortic valves and cerebrovascular accident. Therefore, if malposition is identified, lead extraction should be performed right away, as delaying such procedure carries a risk of systemic embolization from lead manipulation in the future. If lead malposition has to be delayed, anticoagulation is reasonable to prevent cerebrovascular accident. SV-ASD repair may be considered as well. In our case report, we aim to aware clinicians on the rare presentation of SV-ASD, and diagnostic tools available to recognize the defect and to further understand the management of malpositioned pacemaker lead in individuals with SV-ASD.

Case report

A 75-year-old male was referred to our institution for an upgrade of his dual chamber pacemaker to biventricular defibrillator (BiV-ICD) due to his chronic cardiomyopathy, and for the management of his malpositioned right atrial pacemaker lead in the left atrium. Upon initial evaluation at our facility, the patient was noted to be in good health. He was able to perform his activities of daily living without limitations. The patient had no exertional symptoms and furthermore denied chest pain, shortness of breath, lightheadedness, palpitations. Physical examination was significant for grade II/VI systolic murmur at the left upper sternal border and residual weakness in his fourth and fifth digits of the right hand from his prior cerebrovascular accidents (CVA). Electrocardiogram (ECG) revealed atrial-sensed and ventricular-paced rhythm at 81-beats per minute.

Past medical history

The patient's medical history was significant for chronic alcohol use, hypertension, non-ischemic cardiomyopathy, and complete heart block requiring placement of dual chamber pacemaker with atrial and ventricular leads implanted in 2017. Additionally, the patient suffered from CVAs in 2018 and 2021. There was no significant family history reported including any history of heart disease or congenital heart disease.

Investigation

The patient was noted to be in complete heart block in 2017, and subsequently underwent a placement of dual chamber pacemaker. Given no intra-operative complication, it is suspected that post-procedural chest radiography to identify lead placement was not obtained. Months later in 2018, the patient suffered a CVA. At that time, cardiac evaluation with transthoracic echocardiogram (TTE) revealed a normal ejection fraction (EF) with moderately elevated pulmonary artery pressures. During this investigation, unexpectedly, the right atrial pacemaker lead tip was noted to be in the left atrium. Patent foramen ovale (PFO) was suspected to be the cause of the inadvertant lead placement, and the malpositioning was confirmed with non-contrasted computed tomography (CT) of the chest. The patient's CVA in the setting of malpositioned lead was suspicious of a thrombo-embolic event secondary to thrombus formation on the pacemaker lead located in the left atrium. Therefore, the patient was promptly started on anticoagulation to reduce future thrombo-embolic events. A year later, on surveillance TTE, his EF was noted to be 30–35 %. He was suspected to have alcoholic cardiomyopathy given his history of alcohol use and he was appropriately started on guideline-directed medical therapy (GDMT); however, his EF remained chronically reduced. Therefore, he was referred to our facility for upgrade of his pacemaker to BiV-ICD. As mentioned earlier, patent foramen ovale was suspected to be the cause of the malpositioned right atrial lead tip in the left atrium, therefore to further evaluate the defect, the patient underwent transesophageal echocardiogram (TEE) at our facility. TEE confirmed the misplaced atrial lead, and interestingly revealed a superior sinus venosus atrial septal defect (SV-ASD) with the lead transversing from the superior vena cava to a left posterior atrial position (Fig. 1, Fig. 2) with no visible thrombi detected on the atrial lead tip. Right heart catheterization noted a severe left-to-right shunt, a significant step-off from the superior vena cava to the right atrium of 25 %, and pre-capillary pulmonary hypertension with a right ventricular systolic pressure of 50 mmHg. Ischemic evaluation with coronary angiography revealed non-obstructive coronaries.

Fig. 1.

Three-dimensional view at the mid-esophageal bi-caval view showing the right atrial pacemaker lead entering the left atrium through the sinus venosus atrial septal defect. ASD = Atrial septal defect, SVC = superior vena cava.

Fig. 2.

(A) Saline bubble study confirming the defect between the left and right atrium. (B) Color Doppler with turbulence between left and right atrium. LA = left atrium, RA = right atrium, ASD = Atrial septal defect.

Management

SV-ASD is typically diagnosed in the early years of life. Its incidental discovery in patients over the age of 60 years is extremely rare. Our patient's late finding of SV-ASD along with malpositioned right atrial lead in the left atrium led to a multidisciplinary discussion regarding closure of the defect and a possible lead extraction. SV-ASD could have been surgically repaired; however, it was felt that the surgical repair risk outweighed the benefits in this individual. Additionally, extracting the chronic pacemaker lead was deferred as well, as the device was performing without difficulties, the patient was chronically anticoagulated without any adverse bleeding events on it, and lastly, extracting the pacemaker lead could lead to a potential dislodgement of a thrombus from the pacemaker lead tip, leading to another CVA. After an extensive discussion with the patient and his family, it was decided that the patient would be continued on lifelong anti-coagulation with no surgical interventions or plans of lead extraction at this time. Furthermore, the patient was recommended to abstain from alcohol use as his depressed ventricular function was suspected to be alcohol cardiomyopathy. Lastly, BiV-ICD upgrade was postponed as well, as it was believed that the patient would not benefit from the upgrade as the patient's hemodynamic challenges were from the interatrial shunting, and not his cardiomyopathy.

Discussion

Misplacement of the atrial pacemaker lead in the left atrium is rare and occurs in the setting of either lead entering the left atrium through subclavian artery or from the right atrium to left atrium through PFO or ASD [1]. SV-ASD was first described in 1858, and accounts for 4–11 % of ASDs [2]. In SV-ASD, there is an interatrial connection caused by the lack of a common wall between the superior vena cava and pulmonary veins [3]. This interatrial connection allows for inadvertent lead malpositioning. Imaging modalities such as ECG-gated multidetector cardiac computed tomography (MDCT), TTE, TEE, and cardiac magnetic resonance (CMR) imaging can be utilized to detect SV-ASDs [4]. TEE is superior to TTE in diagnosing SV-ASD because of its posterior location. TTE has been noted to have a low sensitivity of approximately 10 % for detecting SV-ASD [5]. Misplaced leads can cause devastating complications and may require correction with lead extraction and closure of identified defects. The most devastating complication associated with inadvertent malposition of the pacemaker tip is cardioembolic event leading to CVAs secondary to thrombus formation on the pacemaker lead tip [6]. Other adverse events associated with malpositioning of the leads include damage to mitral and aortic valves [7]. If misplacement is noted early after implantation, lead extraction or adjustment should be performed as delayed extraction carries a risk of systemic embolization from lead manipulation in the future. Therefore, a careful review of chest radiograph is crucial after pacemaker implantation to look for lead malpositioning, and if present, allowing for an early intervention. If lead malpositioning is identified later, or extraction has to be delayed for other reasons, anticoagulation with direct-acting oral anticoagulant or warfarin is reasonable to prevent cardio-embolic events [8]. If a patient is noted to have a failure of anticoagulant therapy, is unable to tolerate anticoagulation due to adverse bleeding events, or there is plan for a concomitant cardiac surgery, lead extraction at that time may be feasible [9]. In young patients, SV-ASD repair should be considered as there is very low morbidity and mortality associated with the surgery [2]. Surgical risks may outweigh benefits in elderly patients with SV-ASD, therefore extensive discussion with the patient is recommended prior to proceeding with any surgical intervention in this group.

Follow-up

The patient is currently being closely followed up in the electrophysiology clinic for routine assessment of his pacemaker, and by a heart failure specialist for optimization of his GDMT. Repeat TTE is scheduled to be performed after patient's GDMT is fully optimized in the upcoming months.

Conclusions

SV-ASD is rare, and this defect can allow for lead malpositioning during pacemaker placement which can lead to catastrophic cardioembolic events. MDCT, CMR, and TEE are useful imaging modalities for diagnosing the SV-ASD defect. In all individuals undergoing pacemaker placement, a chest radiograph must be obtained after the procedure to evaluate lead positioning. If lead malpositioning is detected early, prompt intervention with lead extraction or adjustment is recommended. If lead malpositioning is identified later, treatment with an anticoagulant is feasible, as long as no adverse bleeding risks are noted. SV-ASD repair may be an option in certain individuals after thorough risks versus benefits discussion with the patient. Lastly, all stroke work ups should include a bubble study when pulmonary hypertension is noted on the TTE.

Funding support and author disclosures

The authors have no relationships relevant to the contents of this paper to disclose.

Patient permission/consent statement

Multiple attempts were made to obtain consent for the case report; however, the authors were unable to contact the patient therefore informed consent for patient information to be published in this article was not obtained. Additionally, no identifying information is used in our report.