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A rare complication of implantable cardiac defibrillator placement

Background Implantable cardiac defibrillators (ICD) are a popular and effective option in heart failure with left ventricular systolic dysfunction patients. Although frequently underdiagnosed, inadvertent malposition can lead to endocardial damage and thrombotic events. As ICD implants tend to increase in the following years, the recognition of their complications is critical. Case presentation The authors present a case of a 64-year-old woman with advanced heart failure and ICD malposition. This accidental discovery was denounced by the presence of a right bundle branch block pattern and later confirmed by echocardiography which showed the lead tip in contact with the mid segment of the left ventricular antero-lateral wall. As the patient hospitalisation was complicated with refractory ascites and cardiogenic shock, she underwent cardiac transplantation, with no recurrence of heart failure symptoms. Conclusions An electrocardiogram showing a right bundle branch block pattern during VVI pacing should arise the suspicion of inadvertent placement of a pacing/ICD lead. The many facets of echocardiography should be used for the diagnosis of this complication, as they were paramount in this case, as highlighted.


Background
Implantable cardiac defibrillators (ICD) are a well-established treatment of heart failure patients with left ventricular systolic dysfunction who are at risk for life-threatening ventricular arrhythmias. As indications for its placement widen, the number of ICD implants also increases and complications arise. The inadvertent malposition of an ICD lead in the left ventricle is a rare complication and may remain undiagnosed for many years. As this lead position may end up in endocardial damage and thrombotic events, its recognition should be prompt. Here, we present a challenging case of a patient with a previous ICD implant who arrived at our department with an electrocardiogram showing a right bundle branch block pattern during VVI pacing. The many facets of echocardiography were paramount to the diagnosis of the complication, as highlighted in this case.

Case Presentation
A 64-year-old woman with multiple previous hospitalizations for acute heart failure was admitted for shortness of breath, peripheral oedema and increasing abdominal size in her local hospital emergency 3 department with subsequent hospitalisation. She had a past history of idiopathic dilated cardiomyopathy with severe biventricular systolic dysfunction, secondary severe mitral and tricuspid regurgitation and permanent atrial fibrillation. As part of the sequence of heart failure therapies, the patient also had a previous implant of an ICD for primary prevention 5 years before.
During hospitalization the patient developed diverse infectious complications which contributed to a slow resolution of acute heart failure, with need of many days of inotropic and vasopressor support and subsequent sub optimization of heart failure therapy. As the patient was recognized as having criteria for advanced heart failure, she was referred and transferred to our advanced heart failure centre.
Following admission to our hospital, an electrocardiogram (ECG) was performed, showing ventricular pacing with right bundle branch block (RBBB) pattern in V1 through V5 leads and negative QRS in I and aVL leads (Figure 1), which raised suspicion of ICD lead malposition. Chest radiography was performed also showing an abnormal lead path, suggestive of implantation of the lead in the left ventricle ( Figure 2). In order to confirm our suspicion, our patient then performed a transthoracic echocardiogram, which showed biventricular dilatation with moderate systolic dysfunction, severe mitral and tricuspid regurgitation and signs of right ventricular pressure overload with plethoric inferior vena cava and abnormal septal motion with systolic "flattening" towards the left ventricle.
Peak systolic gradient between right ventricle and the right atrium was normal, probably underestimated because of right ventricular dysfunction and severe enlargement of the right atrium.
However, the implanted ICD appeared to pass through the interatrial septum, with its lead tip in Initially, our patient registered an important decrease in body weight and improvement in symptoms, however, after many days of stay her hospitalisation was complicated with refractory ascites and cardiogenic shock, with fast progression in INTERMACS classification. As our patient reached INTERMACS level 2, we launched a desperate appeal for cardiac transplantation, as neither extracorporeal membrane oxygenation nor left ventricular assist devices were available at our center at the time. After a couple of days, we got contacted as there was an available heart, and our patient was promptly transferred to our cardiac surgery unit where she underwent successful orthotopic heart transplantation. Immediate post-operative course was favourable with extubation after 24 hours, requiring inotropic support with dobutamine for 2 days with no need for mechanical support. The patient was discharged after 72 days after transplantation, and to this day remains symptom-free with no further hospitalizations.

Discussion And Conclusion
Cardiac implantable electronic devices are a safe and effective way of treating arrhythmias, with increasing number of implants as indications widen and, as more devices are used, subsequent increase in generator replacements 1 . ICD and pacemaker leads are conventionally placed in the right ventricle and right atrium with the leads coursing the subclavian vein and superior vena cava.
However, in some cases, there can occur lead malposition, which remains underdiagnosed as patients can be asymptomatic and fluoroscopic guidance during implantation can be misleading 2,3 .
Furthermore, lead thresholds are not always helpful in the diagnosis, as they can be perfectly normal during patient follow-up 3,4 , which was the case of our patient. As the ICD lead is expected to be implanted in the right ventricular apex, pacing is expected to produce a left bundle branck block pattern. As in the case of our patient, the presence of a paced RBBB pattern must rise suspicion of lead malposition. Sites reported to be associated with the pattern are left ventricular malposition, coronary sinus implantation, lead perforation and pseudo-RBBB even in right ventricular lead placement 5,6 . Chest radiography is routinely performed after lead placement, generally in order to In our case, as the patient underwent cardiac transplantation for reasons not related to lead malposition, lead extraction did not constitute a problem for patient management. However, if we had to extract the lead, it would probably prove problematic as the lead was implanted 5 years before.
When a paced RBBB pattern is seen in a patient with previous ICD implantation, lead malposition in 6 the left ventricle should be suspected. ECG is a very useful diagnostic tool and should be performed while under pacing, if necessary forcing it with a magnet, in order to clarify the position of cardiac stimulation, paramount for clinical suspicion in our case. Chest radiography with posteroanterior and lateral views can also help with the diagnosis, showing an abnormal lead path. However, it can be insufficient because left ventricular position can be mistaken for coronary sinus position. Therefore, echocardiography is crucial to diagnose lead malposition and its complications, as a readily available diagnosis tool capable of locating lead position and following its course. Computed tomography scan may be needed when other exams fail to diagnose lead malposition and suspicion remains high 10 .

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Competing interests
The authors declare that they have no competing interests

Funding
The authors received no specific funding for this work