Systematic review of electrophysiology procedures in patients with obstruction of the inferior vena cava.

AIMS: The objective of the study was to conduct a systematic review to describe and compare the different approaches for performing cardiac electrophysiology (EP) procedures in patients with interrupted inferior vena cava (IVC) or equivalent entities causing IVC obstruction. METHODS: We conducted a structured search to identify manuscripts reporting EP procedures with interrupted IVC or IVC obstruction of any aetiology published up until August 2020. No restrictions were applied in the search strategy. We also included seven local cases that met inclusion criteria. RESULTS: The analysis included 142 patients (mean age 48.9 years; 48% female) undergoing 143 procedures. Obstruction of the IVC was not known before the index procedure in 54% of patients. Congenital interruption of IVC was the most frequent cause (80%); and, associated congenital heart disease (CHD) was observed in 43% of patients in this setting. The superior approach for ablation was the most frequently used strategy (52%), followed by inferior approach via the azygos or hemiazygos vein (24%), transhepatic approach (14%), and retroaortic approach (10%). Electroanatomical mapping (58%), use of long sheaths (41%), intracardiac echocardiography (19%), transesophageal echocardiography (15%) and remote controlled magnetic navigation (13%) were used as adjuncts to aid performance. Ablation was successful in 135 of 140 procedures in which outcomes were reported. Major complications were only reported in patients undergoing AF ablation, including two patients with pericardial effusion, one of whom required surgical repair, and another patient who died after inadvertent entry into an undiagnosed atrioesophageal fistula from a previous procedure. CONCLUSION: The superior approach is most frequent approach for performing EP procedures in the setting of obstructed IVC. Transhepatic approach is a feasible alternative, and may provide a "familiar approach" for transseptal access when it is required. Adjunctive use of long sheaths, intravascular echocardiography, electro-anatomical mapping and remote magnetic navigation may be helpful, especially if there is associated complex CHD. With careful planning, EP procedures can usually be successfully performed with a low risk of complications.

Transseptal puncture performed with the new needle-free 'SafeSept' guidewire: a multicentre experience.

PURPOSE: Increasing numbers of transseptal punctures (TSP) are performed for different cardiac interventions, especially for left atrial (LA) ablation of atrial fibrillation (AF). Significant TSP-related complications may occur even by experienced operators. Any strategies to mitigate these should be adopted. Previous reports have confirmed the safety and efficacy of the first generation nitinol guidewire for TSP. The objective was to assess the safety and efficacy of a new nitinol 'needle free' SafeSept guidewire (NFSG) for TSP. The distal J-shaped tip (0.014 in.) of the NFSG is unchanged in design; however, the shaft is thicker (0.0315 in.) and stiffer. METHODS: This is a multicentre study evaluating TSP without a transseptal needle, using the NFSG via a standard transseptal sheath-dilator, in patients with an indication for TSP. RESULTS: A total of 145 consecutive unselected patients were studied. The mean patient age was 59 ± 15. Thirty-one (21.4%) were female and 43 (29.7%) had a previous procedure requiring TSP. The mean transverse LA diameter was 4.0 ± 0.8 cm. AF or LA tachycardia comprised the major indication for TSP (n = 115). Transesophageal echocardiography for direct guidance of TSP was utilised in cases performed under general anesthesia (n = 66, 45.5%). LA access by TSP using the NFSG was achieved successfully in 100% of cases after 1.6 ± 2.3 passes. There were no TSP or other major procedural complications. CONCLUSIONS: Use of the NFSG appears to be a safe and effective method in performing TSP. The major improvement in the design of the NFSG is that TSP can be performed without a transseptal needle and exchange for a standard guidewire is not required upon establishing LA access.

Catheter Ablation of Atypical Atrioventricular Nodal Reentrant Tachycardia.

BACKGROUND: Because of its low prevalence, data on atypical atrioventricular nodal reentrant tachycardia (AVNRT) are scarce, and the optimal ablation method has not been established. Our study aimed at assessing the efficacy and safety of conventional slow pathway ablation, as applied for typical cases, in atypical AVNRT. METHODS: We studied 2079 patients with AVNRT subjected to slow pathway ablation. In 113 patients, mean age 48.5±18.1 years, 68 female, atypical AVNRT or coexistent atypical and typical AVNRT without other concomitant arrhythmia was diagnosed. Ablation data and outcomes were compared with a group of age- and sex-matched control patients with typical AVNRT. RESULTS: Fluoroscopy and radiofrequency current delivery times were not different in the atypical and typical groups, 20.3±12.2 versus 20.8±12.9 minutes (P=0.730) and 5.9±5.0 versus 5.5±4.5 minutes (P=0.650), respectively. Slow pathway ablation was accomplished from the right septum in 110 patients, and from the left septum in 3 patients, in the atypical group. There was no need for additional ablation lesions at other anatomic sites, and no cases of atrioventricular block were encountered. Recurrence rates of the arrhythmia were 5.6% in the atypical (6/108 patients) and 1.8% in the typical (2/111 patients) groups in the next 3 months following ablation (P=0.167). CONCLUSIONS: Conventional ablation at the anatomic area of the slow pathway is the therapy of choice for symptomatic AVNRT, regardless of whether the typical or atypical form is present.

Atypical atrioventricular nodal reentrant tachycardia: prevalence, electrophysiologic characteristics, and tachycardia circuit.

AIMS: This study aimed at assessing the prevalence, electrophysiologic characteristics, and mechanism of atypical atrioventricular nodal reentrant tachycardia (AVNRT). METHODS AND RESULTS: We studied 925 consecutive patients with AVNRT. Atrial-His (AH) and His-atrial (HA) intervals were measured during atypical AVNRT (HA > 70 ms), and compared with measurements in 34 patients with typical (slow-fast) AVNRT. Assuming that conduction velocity over the fast pathway is similar in the anterograde and retrograde directions, the AH interval during the fast-slow form should be smaller than the HA during slow-fast. Atypical AVNRT was diagnosed in 59 patients (6.4%), median age 50 years (range 19-79 years), and 37 (59.7%) of them female. Fast-slow AVNRT was diagnosed in 44 patients (74.5%), and slow-slow AVNRT in 9 patients (15.2%). The remaining six patients (10.2%) could not be reliably classified due to inconsistent AH, and HA/AH patterns or variable intervals. Tachycardia induction with anterograde conduction jumps was seen in two patients with the fast-slow, and in three patients with slow-slow or intermediate forms. Atrial-His in the fast-slow group was significantly longer than HA in the slow-fast group, 99.7 ± 40.5 ms vs. 45.8 ± 7.7 ms, P < 0.001. Tachycardia cycle length was longer in fast-slow compared with slow-fast, 379.1 ± 68.5 ms vs. 317.1 ± 42.8 ms, P < 0.001. CONCLUSION: Of AVNRT cases, 6.4% are atypical and may display patterns that do not necessarily correspond to the fast-slow or slow-slow conventional types. Atypical fast-slow and typical AVNRT do not appear to utilize the same limb for fast conduction.

Immediate balloon deflation for prevention of persistent phrenic nerve palsy during pulmonary vein isolation by balloon cryoablation.

BACKGROUND: Persistent phrenic nerve palsy is the most frequent complication of cryoballoon ablation for atrial fibrillation and can be disabling. OBJECTIVES: To describe a technique-immediate balloon deflation (IBD)-for the prevention of persistent phrenic nerve palsy, provide data for its use, and describe in vitro simulations performed to investigate the effect of IBD on the atrium and pulmonary vein. METHODS: Cryoballoon procedures for atrial fibrillation were analyzed retrospectively (n = 130). IBD was performed in patients developing phrenic nerve dysfunction (n = 22). In vitro simulations were performed by using phantoms. RESULTS: No adverse events occurred, and all patients recovered normal phrenic nerve function before leaving the procedure room. No patient developed persistent phrenic nerve palsy. The mean cryoablation time to onset of phrenic nerve dysfunction was 144 ± 64 seconds. Transient phrenic nerve dysfunction was seen more frequently with the 23-mm balloon than with the 28-mm balloon (11 of 39 cases vs 11 of 81 cases; P = .036). Balloon rewarming was faster following IBD. The time to return to 0 and 20° C was shorter in the IBD group (6.7 vs 8.9 seconds; P = .007 and 16.7 vs 37.6 seconds; P<.0001). In vitro simulations confirmed that IBD caused more rapid tissue warming (time to 0°C, 14.0 ± 3.4 seconds vs 46.0 ± 8.1; P = .0001) and is unlikely to damage the atrium or pulmonary vein. CONCLUSIONS: IBD results in more rapid tissue rewarming, causes no adverse events, and appears to prevent persistent phrenic nerve palsy. Simulations suggest that IBD is unlikely to damage the atrium or pulmonary vein.