With advancements in both device-based therapy as well as ablation strategies, the field of electrophysiology offers treatments for congestive heart failure, sudden cardiac death, bradyarrhythmias, and tachyarrhythmias. Both the benefit and challenge of advanced treatments are that we are able to manage older patients, those with more complex diseases, and those who have undergone surgical and EP procedures. As a result, in the field of electrophysiology, venous occlusions are more frequently encountered. It is important to be aware of etiologies as well as medical and invasive treatments. The treatment strategy needs to be tailored uniquely and creatively to each patient.
Venous thrombosis may be a result of either inherited or acquired disorders. Inherited risk factors include Factor V Leiden, prothrombin, protein S, protein C, and antithrombin mutations. However, acquired disorders are more frequently responsible for those occlusions encountered in the EP laboratory. Cardiovascular risk factors including obesity, diabetes mellitus, as well as stages 3-4 chronic kidney disease have been shown to increase the risk for venous thromboembolism. Other acquired risk factors include malignancy, surgery, trauma, pregnancy, medications, and immobilization. Placement of central venous catheters or cardiovascular implantable electronic devices (CIEDs) predisposes the patient to venous thrombosis and potential vessel occlusion.
We describe two cases of venous thrombosis — one of the upper extremity and the other of the lower extremity — that were encountered in the EP laboratory. These cases illustrate the need to recognize and troubleshoot venous occlusions.
A 75-year-old female with a history of an ischemic cardiomyopathy, ejection fraction 25%, and status post dual chamber ICD was transferred for the management of ICD shocks. The left-sided dual chamber device was originally implanted five years ago. However, three months ago, the patient underwent a right ventricular (RV) lead revision. During the procedure, the old RV lead was abandoned and capped, and a new RV ICD lead was placed ipsilateral to the old system. Upon presentation to our hospital, interrogation revealed inappropriate shocks as a result of noise on the RV lead. The pacing impedance was <200 ohms, and the pacing threshold was >5 volts at 0.5 ms. The patient was taken to the EP laboratory for RV lead revision.
Venography of the left upper extremity was performed and demonstrated partial occlusion of the left subclavian vein with significant collateralization (Figure 1). Via a modified Seldinger technique, a guidewire was advanced into the subclavian vein. The RV lead implanted three months ago was removed with manual traction. Following sequential dilatations with additional sheaths, the new RV lead was advanced via the ipsilateral subclavian vein without complications. The decision was made to leave the previously abandoned five-year-old RV lead in place. Removal of that lead would have required laser lead extraction, and it was not immediately necessary to subject a frail, elderly woman to the potential risks of that procedure.
A 33-year-old male presented to the emergency room with complaints of palpitations and syncope while driving, which resulted in a motor vehicle accident. In the emergency room, he developed supraventricular tachycardia at a rate of 205 bpm, which responded to adenosine. His cardiovascular work-up included an echocardiogram, which was within normal limits, and three months later he presented for an electrophysiology evaluation. Of note, he did not report any vascular symptoms such as lower extremity edema, numbness, or pain.
He was taken to the EP laboratory for an electrophysiology study (EPS) and radiofrequency ablation (RFA). Bilateral femoral venous access was obtained without complications. Attempts were made to advance a quadripolar catheter from the right and left femoral veins. However, on both occasions, the catheter could not be advanced through the inferior vena cava (IVC). Thereafter, attempts were made to advance a hydrophilic guidewire into the IVC. At the same site, resistance was encountered. Venography was performed, and intravenous contrast demonstrated complete IVC occlusion with the presence of significant collateralization (Figure 2). As a result, venous access from the lower extremities was abandoned. Given the significant nature of the patient’s symptoms and the importance of performing a curative procedure, we did not wish to abandon the procedure. The right internal jugular vein was then accessed in order to advance the coronary sinus and right ventricular apical catheters. A diagnostic EPS was performed, which resulted in the induction of a supraventricular tachycardia. In the tachycardia, there was evidence of eccentric VA conduction with the earliest atrial activation in the distal coronary sinus, consistent with a left-sided bypass tract. The right femoral artery was accessed without complication in order to perform a left lateral accessory pathway ablation via a retrograde arterial approach. Two lesions resulted in a successful ablation. As a result, the patient underwent a safe and successful RFA in spite of complete IVC occlusion.
As demonstrated by the above cases, venous thromboses that result in occlusions require innovative therapies. Occlusions vary in cause, location, pathophysiology, and whether the occlusion is partial or complete. As a result, the management in the setting of catheterization presents a unique set of challenges. Options for management of venous occlusion include conservative treatment (when the patient is asymptomatic), anticoagulation, thrombolysis, lead removal/extraction (which may include the use of powered sheaths), percutaneous transluminal balloon venoplasty, stenting, or surgery. For acute occlusions, catheter-directed thrombolysis reduces the risk of bleeding when compared to systemic thrombolysis, and achieves higher rates of clot resolution. However, acute occlusions in EP are likely the result of a recent surgical procedure and thus, thrombolysis is precluded. In addition, thrombotic occlusions over two weeks in age are typically less responsive to pharmacothrombolysis. Therefore, thrombolysis is rarely utilized in EP.
The first case depicts that intravenous catheters and leads are notorious for causing endothelial trauma and inflammation, which can cause thrombosis. Thrombosis alone is not an indication for lead removal and, in fact, is quite common and asymptomatic. However, if there is a need for lead revision or upgrade requiring ipsilateral insertion of another lead, then thrombosis may pose a problem. Unfortunately, over time, these venous occlusions are not only a result of clot formation but also fibrosis. Mechanical options for disruption of fibrous attachments include the use of locking stylets, telescoping sheaths, and excimer laser sheaths that dissolve rather than mechanically shear tissue. These procedures are technically demanding and necessitate surgical backup. In our case, since one of the leads was recently implanted, laser lead extraction was not required. Removal of the recently implanted lead via traction was sufficient to create “real estate” for a new lead.
Another option for managing venous occlusion is percutaneous transluminal balloon venoplasty, which may be followed by stenting. Venous angioplasty alone is typically not sufficient for maintaining patency because of low intravenous pressure. Consequently, venous stenting is often required for long-term patency, and may be an option for chronically thrombosed veins. This intervention may be performed in any symptomatic venous narrowing in vessels ranging in caliber from the superior vena cava, inferior vena cava, subclavian veins, innominate veins, and to the iliac veins. Of note, if there is a preexisting lead(s), then the lead(s) should be first removed. It is not recommended to deploy a stent such that the lead would be entrapped between the stent and the vessel. If venoplasty and stenting are not an option, the last consideration is surgery.
Of course, another option is to find a different access site than the occluded one, as was our approach in the second case. The patient was asymptomatic from the IVC obstruction, which had developed an array of collaterals. There was no need to perform percutaneous angioplasty and stent placement. However, we did need to perform an ablation. The most straightforward approach was to find different access sites such as the internal jugular vein and the femoral artery. There are also device cases in which one may favor a contralateral approach. If the patient is elderly and/or has significant comorbidities or, for example, an arteriovenous fistula, then it may be preferable to abandon leads and proceed with a new device on the other side.
In summary, venous occlusions are by no means concrete obstacles in the EP laboratory. The increasing complexity of our procedures and patients requires innovative and adaptable approaches to patient care.