Although catheter ablation is typically performed through the femoral vein, complete or partial occlusions can hinder the procedure's success by making it challenging to stabilize the catheter or reach the ablation site. To address such challenges, alternative approaches such as the superior vena cava approach for right-sided arrhythmias and the retrograde aortic approach for left-sided arrhythmias are recognized methods. The patient has provided informed consent for the publication of this case report.

A 64-year-old female patient was referred to our center due to frequent palpitation attacks. The patient underwent an electrophysiological study, during which two femoral sheaths were placed in the femoral vein. Attempting to access the coronary sinus diagnostic catheter into the right atria, we encountered difficulty as the catheter tip was bent and could not enter the right atrial chamber (Video 1). Venography revealed near-complete interruption of the vena cava (Video 2). Consequently, we opted to use a 0.035 hydrophilic guidewire to navigate through a small passage into the right atria. Two guidewires were introduced through the occluded segment into the right atria, followed by placement of two transseptal sheaths (PREFACE® Braided Guiding Sheath, Johnson & Johnson Medical NV/SA, USA) in the right atrial cavity over these wires (Video 3 and Video 4). Subsequently, a decapolar coronary sinus catheter and a diagnostic catheter were positioned in the coronary sinus and high right atrial position, respectively. Atrial decremental pacing demonstrated crossover and 1:2 response. Programmed stimulation induced supraventricular tachycardia with a VA interval of 50 msec. All other examinations supported the diagnosis of atrioventricular nodal reentrant tachycardia. Interruption of ventricular overdrive pacing resulted in a V-A-V response, and His refractory premature ventricular single-beat stimulation did not advance or reset retrograde A. Following the diagnosis, the diagnostic catheter was exchanged with an ablation catheter (Marinr MC ablation catheter, Medtronic, Minneapolis, MN, USA). Koch triangle was mapped with the ablation catheter to identify an appropriate location for radiofrequency application, and successful slow pathway ablation was performed (Video 5).

Atrioventricular nodal reentry is the most common form of paroxysmal supraventricular tachycardia, and the primary therapeutic option for this type of arrhythmia is catheter ablation.¹ Both anatomical and electrical targets have been developed for ablation, which are situated within the Koch triangle.² Despite established techniques for the ablation procedure, anatomical obstacles can still pose challenges. These obstacles may include a narrow Koch triangle, a large coronary sinus ostium, or other factors that hinder catheter entrance into the right atrial chamber, as described in our case.

Interruption of the inferior vena cava (IVC) is a rare congenital venous anomaly often associated with heterotaxy syndromes. The prevalence of IVC interruption among patients undergoing routine imaging (computed tomography or echocardiography) ranges from 0.15% to 0.25%.³ Generally, if there is continuity via the azygos vein, procedures can be completed via femoral access. However, the most commonly utilized approach for these patients is through subclavian or jugular veins.⁴ Recently, there have been case reports describing procedures performed via hepatic vein access.⁵ Our case is unique among others described in the literature⁶⁷ because of the interruption in the superior segment, nearly at the veno-right atrial junction.

Transthoracic echocardiography did not reveal any valve or embryonic remnants. In our case, we opted to utilize two long sheaths because the occluded segment was superior to the hepatic vein, and there was an opportunity to pass wires through the incompletely occluded segment, which fortunately we were able to achieve. Although we had limited maneuvering space, it proved to be sufficient for successful slow pathway ablation.

In conclusion, in cases of partial occlusions in the superior parts of the vena cava, catheter ablation with long sheaths is feasible. In such scenarios, utilizing the femoral vein route may be preferred over an unstable route like the superior vena cava.

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