The successful implantation of CRT-D using the catheter within catheter technique in a patient with a type IIIA persistent left superior vena cava

Persistent left superior vena cava (PLSVC) is a congenital anomaly where the left-sided vena cava, which usually regresses during fetal development, persists. Double superior vena cava resulting from a PLSVC is indeed a rare phenomenon. In the general population, the incidence of this condition is reported to be between 0.3% and 2.1%.^[1] While this anatomical variation is often asymptomatic and discovered incidentally, it becomes relevant in certain clinical scenarios. Indeed, the presence of a PLSVC and double superior vena cava can pose challenges as incorrect positioning and result in failure, particularly during the implantation of pacemakers, implantable cardioverter-defibrillators, and cardiac resynchronization therapy (CRT) devices [CRT-pacemaker (CRT-P)/CRT-defibrillator (CRT-D)].^[2–4] Several classifications for PLSVC have been documented in the literature. The most commonly utilized one is Schummer’s classification of the supracardiac venous system. According to this classification, type IIIA cases connecting beween the two superior vena cava (SVC) through the innominate vein are observed between 0.08% and 0.56%.^[5] Here we describe a case of type IIIA PLSVC identified during the CRT-D implantation and discuss technical considerations for the successful completion of the procedure.

A 76-year-old female patient was referred to our hospital for CRT-D implantation due to multiple hospital admissions for heart failure despite optimal medical treatment. Her electrocardiogram showed atrial fibrillation and left bundle branch block. Transthoracic echocardiography revealed a left ventricular ejection fraction of 30% with Simpson’s method, along with left ventricular dilation (62 mm), mild mitral regurgitation, and mild tricuspid regurgitation. Before CRT-D implantation, we decided to perform venography. Venography revealed the presence of PLSVC and also indicated communication with the right SVC through a small vein called the innominate vein (type IIIA) (supplemental material, Video 1). The anatomical diagram of our case is illustrated in Figure 1. Confronted with this scenario, our decision was to access the right SVC for the ease of right ventricular (RV) lead implantation and access the left SVC by traversing through the coronary sinus (CS) to facilitate the left ventricular lead. To begin, we successfully threaded the guide wire into the right SVC by employing a 6-Fr Judkins right catheter. Coronary arteriography catheter with rotational movements passing through innominate vein. For the active fixation lead, we utilized a rigid straight stylet. Upon reaching the atrium, we navigated the tricuspid valve using a specialized stylet, positioning the lead at the RV apex (supplemental material, Video 2). The electrical parameters demonstrated favourable values (pacing impedance: 560 Ω; sensed R: 7.2 mV; pacing threshold: 0.6 V/0.5 ms). Through the left SVC, CS angiography identified a suitable lateral vein of the CS. However, the presence of an acute angle at the left subclavian/left SVC, combined with the high take-off angle of the targeted vein, rendered the advancement of the CS lead impossible using a curved outer delivery sheath. Consequently, we redirected our efforts towards another posterolateral vein using the curved outer delivery sheath with an Amptlaz 1 catheter and Amplatz 2 catheter. We passed a hydrophilic wire through this catheter, but it did not provide the necessary support. Subsequently, we sent an extra stiff wire, which also failed to offer the required support, leading to the entire system being withdrawn. To address this issue, we utilized an inner subselector delivery sheath with a right-angled tip to reach and engage the ostium of the posterolateral vein. However, this also proved unsuccessful. We conducted venography again to search for another branch and found the middle cardiac vein. In the end, we successfully entered the middle cardiac vein of the CS using a curved outer delivery sheath combined with an acute-angled inner subselector sheath and Amplatz 1 catheter. Following this, a straight quadripolar CS lead was positioned, demonstrating satisfactory electrical parameters (pacing impedance: 800 Ω; pacing threshold: 0.7 V/0.5 ms). Subsequently, the RV lead was repositioned due to its proximity to the CS lead and then placed in the RV septum (supplemental material, Video 3). Finally, the battery was inserted into the pocket, and the procedure was completed without complications. The patient refused atrioventricular junction ablation and surgical epicardial lead placement. Left bundle branch pacing was not able to be performed due to technical and commercial reasons. At the 1-year follow-up, the echocardiogram showed that the ejection fraction had increased from 30% to 45%. Rate control was achieved with medical therapy (beta-blocker, digoxin) during follow-up. The average pacing percentage was 90%. Due to the high pacing percentage, effective rate control, and the patient’s preference against atrioventricular node ablation, atrioventricular node ablation was not considered.

Figure 1.

Schematic anatomy of upper venous system.

Persistent left superior vena cava drains into coronary sinus and innominate vein merges right superior vena cava and left superior vena cava.

Anatomical variations in the SVC are usually without symptoms, but they can pose challenges during certain intravascular procedures, including central line placement, and pacemaker, implantable cardioverter-defibrillator, or CRT-P/CRT-D implantation.^[1,2,6] Schummer introduced the most widely accepted classification of the supracardial venous system based on the anatomical relationships of the SVC and its surrounding structures; type I: normal SVC anatomy; type II: only PLSVC exists, without the right SVC; type IIAA: PLSVC and the right SVC exist, with left brachiocephalic vein between both sides; and type IIIB: PLSVC and the right side of the SVC, without left brachiocephalic vein between both sides.^[5] In the literature, a rare case of CRT-D implanted in the PLSVC has been reported, utilizing various techniques.^[1,2,7] In this instance, we present a rare case involving a patient with a type IIIA PLSVC, in which we successfully implanted the left ventricular lead for a CRT-D using a catheter within the catheter. This was achieved through the PLSVC using an outer delivery sheath, an inner subselector delivery sheath, and an Amplatzer 1 catheter.

We employed an innovative approach by utilizing a left-sided technique (via left subclavian-left SVC) for the CS, while simultaneously using the same side to access the right SVC via the innominate vein for the placement of the RV lead. This strategy proved effective in overcoming the challenge posed by an acute subclavian vein/PLSVC angle, PLSVC/innominate vein angle, innominate vein/right SVC angle and CS/tricuspid valve angle.^[2]

Numerous case reports have detailed various strategies to address this challenge, including utilizing an over-the-wire lead system, using an elongated sheath guided by a deflectable catheter, and molding the lead into a pigtail with a 3–4 cm wide loop.^[5] It is essential to note that the unexpected occurrence of a PLSVC often arises, leaving no room for the use of additional unconventional tools.

Another challenge involves positioning the CS lead, particularly when the CS is significantly dilated, as commonly observed in isolated PLSVC, as seen in our case. For approaches through the LSVC, we typically employ the other delivery sheath, inner subselector delivery sheath with an acute or right-angled tip, and Amplatz 1 catheter like a Matryoshka doll. A more curved tip angle is required to engage lateral veins compared to posterior veins. After identifying the target vein through CS venography, simultaneous pulling with clockwise and counterclockwise torquing is employed to engage the target vein. Due to both the angle of the subclavian vein and LPSCV, and the angle between the CS and target branches, advancing the sheaths and lead was very challenging despite the use of an extra stiff wire. In our case, stability of the positioned CS lead was observed once a suitable lead was advanced into the target vein. Active fixation CS lead stability could be considered as an option if instability in the target vein is anticipated. Furthermore, we did not observe a specific tendency for phrenic stimulation in this case. Nevertheless, the presence of acute angulation could limit sheath manipulations and might necessitate repositioning the lead in another vein than initially planned. At first, we placed the RV lead at the apex. However, upon inserting the CS lead into the middle cardiac vein, we observed that the distance between the tips of two leads was very short. Consequently, we repositioned the RV lead to the septum to achieve proper distance between tips of two leads. During the follow-up process, the patient attended their 1^st, 3^rd, and 6^th month check-ups, as well as the 1-year follow-up. No issues were encountered.

During echocardiography in these patients, the enlarged appearance of the CS should prompt consideration of PLSVC. Therefore, a thorough investigation is essential for all identified PLSVC cases prior to central venous access device placement to rule out associated cardiac abnormalities and potential symptoms. Performing venography or computed tomography angiography before the procedure will greatly assist the operator in visualizing the cardiac anatomy. Additionally, it is crucial to document the presence of PLSVC in medical records to ensure that healthcare providers are informed about the pertinent anatomy before proceeding with central venous access procedures.^[1,2,5–7]

Despite the difficulty of implanting CRT-D in PLSVC patients, the procedure can be successfully completed with the appropriate technique and catheter. As a result, venous system imaging with venography should be performed in PLSVC patients. The catheter within the catheter technique proves to be an effective approach in providing sufficient support and navigating through challenging vessels for cardiac resynchronization therapy. The cardiology team performing the invasive procedure should be well-versed and understand various venous system anomalies, different sheaths and support catheters, as well as stylets.

SUPPLEMENTARY DATA

Supplementary data to this article can be found online.