Author + information
- Gianluca Rigatelli, MD, PhD, EBIR∗ (, )
- Fabio Dell'Avvocata, MD,
- Dobrin Vassiliev, MD, PhD,
- Ramesh Daggubati, MD,
- Ashesh Buch, MD, PhD,
- Aravinda Nanjiundappa, MD,
- Massimo Giordan, MD,
- Laura Oliva, RT,
- Dario Adami, RT and
- Paolo Cardaioli, MD
- ↵∗Rovigo General Hospital, Viale Tre Martiri, 45100 Rovigo, Italy.
Right-to-left (R-to-L) shunt caused by patent foramen ovale (PFO) is a dark field for interventionalists, particularly after the conflicting results from the most recent trials regarding PFO transcatheter closure. It seems that the confusing results (negative in the Closure I [Closure or Medical Therapy for Cryptogenic Stroke With Patent Foramen Ovale] trial  and slightly positive in the RESPECT [Randomized Evaluation of Recurrent Stroke Comparing PFO Closure to Established Current Standard of Care Treatment] and PC [Percutaneous Closure of Patent Foramen Ovale in Cryptogenic Embolism] [2,3] trials) might be related to patient selection, in particular anatomical inclusion/exclusion criteria and device choice. We tried to clarify the relationships of different anatomical subtypes and the association of anatomical characteristics of the interatrial septum with risk of recurrent paradoxical embolism and shunt grade.
We retrospectively reviewed the medical and instrumental data of 520 consecutive patients (mean age 44.0 ± 15. 5 years; 355 females) who had been referred to our center over a 10-year period (February 2003 to February 2013) for R-to-L shunt catheter-based closure. Inclusion criteria for percutaneous closure of PFO included the following: 1) a concurrent permanent or shower or curtain shunt pattern on transcranial Doppler with Valsalva maneuver; 2) positive (single or multiple ischemic foci) cerebral magnetic resonance imaging; 3) previous neurologically confirmed stroke or transient ischemic attack; and 4) moderate or large PFO on transesophageal echocardiography. The hospital ethical board approved the study, and written informed consent was obtained from all patients enrolled in the study.
In all patients, the attempt at transcatheter closure was preceded by a mechanical 9-F, 9-MHz, 360° scan probe (UltraICE, EP Technologies, Boston Scientific Corporation, San Jose, California) intracardiac echocardiography. This study was conducted in 2 projections, measuring diameters of the oval fossa, the entire atrial septum length, and rims and thickness with electronic caliper edge-to-edge (4). Four main features were used to analyze patients: 1) diameter of the fossa ovalis (FO); 2) presence and length of the channel; 3) presence and degree of atrial septal aneurysm (ASA), following the classification of Olivares et al. (5); and 4) rim thickness. We also analyzed the presence of Eustachian valve and Chiari's network. We considered eventual additional fenestrations within the fossa as a functional subtype of PFO, despite that, anatomically, they should be considered as secundum atrial septal defects.
Thus, combinations of interatrial septum anatomical features were classified into 4 main anatomical subgroups: type 1, small FO, no ASA, short channel, normal rims; type 2, small FO, no ASA, long channel, normal or hypertrophic rims; type 3, large FO, 4 to 5 ASA, short channel, normal or hypertrophic rims; and type 4, large FO, 3 to 5 ASA, multifenestrated, short channel, normal rims (Table 1).
FO diameter ≤20 mm was found to be statistically correlated to the presence of a tunnelized PFO (r = 0.91, p < 0.001), whereas FO diameter >25 mm was associated with the presence of ASA (r = 0.88, p < 0.001) and a linear correlation between diameter of the FO and ASA severity (the larger the fossa, the more severe the ASA) (r = 0.90, p < 0.001). Type 3 anatomical subtype (odds ratio: 4.1 [95% confidence interval: 1.5 to 8.0]; p < 0.001) and type 2 + Eustachian valve (odds ratio: 4.3 [95% confidence interval: 1.6 to 9.0]; p < 0.001) were the strongest predictors of recurrent ischemic events before transcatheter closure.
Our study suggests that the anatomy of the interatrial septum associated with R-to-L shunt is more complex than commonly thought. The combination of the varieties of such anatomical components identifying 4 main anatomic subtypes may help in better clarifying the pathophysiology of paradoxical embolism, which is unlikely to be dominated by 1 factor only, such as ASA, PFO tunnel, or fenestrations. Intriguingly, our data suggest that the FO diameter plays a role in determining the presence of both tunnelized PFO, when the oval fossa is small (<20 mm), and the presence of aneurysm, when the fossa is large (≥20 mm).
In conclusion, our study showed that in a “real-world” interatrial septum, anatomy greatly differs among patients with R-to-L shunt. The clinical significance of each anatomical pattern seems different: a device closure might be advisable in patients with high-risk anatomical patterns whereas a medical strategy might be adopted in the others.
Please note: Dr. Daggubati is a member of the speaker's bureau for Abbott, AstraZeneca, Eli Lilly, Janssen, Medtronic, and Volcano, and has received research grants from Guerbet and educational grants from Medtronic. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- American College of Cardiology Foundation