Cardiac Function after Percutaneous Closure of Patent
Foramen Ovale

Following the reports by Webster,¹ Lechat² and their colleagues, suggesting a relationship between strokes in young patients and patent foramen ovale (PFO), Bridges and her associates from Boston,³ and we from Madison,^4,5 utilized trans-catheter occlusion of PFO with clamshell and buttoned devices, respectively, to prevent recurrence of cerebrovascular accidents presumably related to paradoxical embolism via the PFO. It should be noted that King and Mills⁶ used their device for this purpose more than a decade earlier. Percutaneous closure of PFOs was thought to be an alternative option to lifelong anticoagulation. Since the initial reports,^3–6 a number of other investigators, referenced elsewhere,⁷ have adopted the concept and technique. Transcatheter closure of PFOs or atrial septal defects was extended to closure of defects with right-to-left atrial shunts associated with previously treated complex congenital cardiac anomalies, including Fontan fenestrations⁸ and platypnea-orthodeoxia syndrome.^9,10
More recently, closure of PFOs has been attempted in the management of atrial right-to-left shunts associated with right ventricular infarction, decompression illness^11,12 and migraine.¹³ The majority of the atrial septal closure devices, as and when they became available, have been used to close PFOs to prevent recurrence of embolism.¹⁴ Some devices were modified, or new devices designed to address the anatomic features of the foramen ovale. Three devices, namely, the PFO-Star™ (Cardia, Inc., Eaagan, Minnesota),¹⁵ the Amplatzer^® PFO Occluder¹⁶(AGA Medical, Plymouth, Minnesota) and the inverted⁸ or hybrid¹⁷ buttoned devices are specifically designed to occlude PFOs.
Despite the extensive use of transcatheter occlusion of PFOs to prevent recurrence of paradoxical embolism, no clear-cut demonstration of benefit compared to anticoagulation was shown. Consequently, several randomized clinical trials to address this issue have been launched. Because of issues related to patient enrollment numbers (too few enrolled), the question remains unanswered at this time. While awaiting these results, it is worthwhile to investigate the follow-up results as well as the effect of the devices on cardiac function. The paper by Yalonetsky¹⁸ in this issue of the Journal is one such attempt.
Yalonetsky et al used Doppler tissue imaging (DTI) to evaluate quantitative assessment of regional myocardial tissue velocities following closure of PFOs prospectively. Fourteen patients aged 51.4 ± 10.1 years were studied prior to and 24 hours, 10 days and 1 month following closure of PFO for prevention recurrence of paradoxical embolism. Nine patients received the Amplatzer septal occluder and 5 underwent Helex septal occluder implantation. No changes in global or segmental ventricular function or myocardial performance index (Tei index) were observed. Of all the Doppler and TDI parameters studied, only two abnormalities were noted: decrease in E-wave deceleration time (p = 0.05), and reduction in systolic motion of the basal interventricular septum (p = 0.03). The authors concluded that the minor changes they documented are without clinical impact, and suggested a large multicenter study with a long follow-up period.
This is a well written paper with laudable objectives, using appropriate study design and recently developed TDI, along with conventional echocardiographic-Doppler studies. However, the number of subjects, as acknowledged by the authors, is very small, and among these, two types of devices were used (Amplatzer and Helex septal occluders), further limiting the conclusions. The duration of follow up was short. Although the authors did not provide the details of the statistical methodology used in the analysis of their data, close examination of the data would indicate that what was interpreted as a statistically significant decrease may not be so if the Bonferroni correction is applied, which is an appropriate statistical tool since multiple comparisons (pre- and 14-hour, 10-day and 1-month postclosure) of the data were made.
In addition, TDI has been shown to be load-dependent. A recent study¹⁹ noted a difference in the systolic TDI parameters after device closure of ASDs in 21 children. They hypothesized that the decrease was due to the mechanical properties of the septal occluder device on the atrial septum. Given that myocardial motion is affected by tethering, it would follow that the septal TDI values would decrease when a large piece of metal (device) is placed in the septum. The authors of the current study¹⁸ are using TDI not only to show myocardial motion abnormalities related to the septal occluder, but also to indicate that there are myocardial performance abnormalities inflicted upon the basal septum by the occluder. Any abnormalities in the TDI can be explained by the presence of the occluder as well as a change in the loading conditions of the ventricle. Strain and strain rate imaging (strain is defined as the deformation of an object, normalized to its original shape; strain rate is the speed at which deformation occurs)^20,21 are more sensitive markers for myocardial performance and are relatively load-insensitive.²² If the authors want to investigate regional ventricular function, regional strain analysis is a much more powerful tool which would take away the influences of the tethering upon the septum caused by the occluder,²³ as well as the decreases in systolic TDI seen by changing loading conditions on the ventricles.
Finally, the commonly used device to close PFOs at the current time is the Amplatzer PFO Occluder, which is less likely to cause septal distortion (compared to the regular Amplatzer Septal Occluder used for ostium secundum atrial septal defect).¹⁶ Consequently, it is preferable to perform studies using load-independent parameters such as strain and strain rate imaging following implantation of the Amplatzer PFO occluder.

References

1. Webster MW, Chancellor AM, Smith HJ, et al. Patent foramen ovale in young patients. Lancet 1988;2:11–12.
2. Lechat P, Mas Jl, Lascault G, et al. Prevalence of patent foramen ovale in patients with stroke. N Engl J Med 1988;318:1148–1152.
3. Bridges ND, Hellenbrand W, Latson L, et al. Transcatheter closure of patent foramen ovale after presumed paradoxical embolism. Circulation 1992;16:83–84.
4. Rao PS, Wilson AD, Levy JM, Chopra PS. Role of “buttoned” double-disk device in the management of atrial septal defects. Am Heart J 1992;123:191–200.
5. Ende DJ, Chopra PS, Rao PS. Transcatheter closure of atrial septal defect or patent foramen ovale with the buttoned device for prevention of recurrence of paradoxical embolism. Am J Cardiol 1996;78:233–236.
6. Mills NL, King TD. Nonoperative closure of left-to-right shunts. J Thorac Cardiovasc Surg 1976;72:371–378.
7. Windecker S, Meier B. Percutaneous closure of patent foramen ovale in patients with presumed paradoxical embolism. In: Rao PS, Kern MJ (eds). Catheter-Based Devices for the Treatment of Noncoronary Cardiovascular Disease in Adults and Children. Lippincott, Williams & Wilkins: Philadelphia, 2003: pp. 111–118.
8. Rao PS, Chandar JS, Sideris EB. Role of inverted buttoned device in transcatheter occlusion of atrial septal defect or patent foramen ovale with right-to-left shunting associated with previously operated complex congenital cardiac anomalies. Am J Cardiol 1997;80:914–921.
9. Rao PS, Palacios IF, Bach RG, et al. Platypnea-orthodeoxia syndrome: Management by transcatheter buttoned device implantation. Catheter Cardiovasc Interv 2001;54:77–82.
10. Delgado G, Inglessis I, Martin-Herrero F, et al. Management of platypnea-orthodeoxia syndrome by transcatheter closure of atrial septal communication: Hemodynamic characteristics and clinical and echocardiographic outcome. J Invasive Cardiol 2004;16:578–582.
11. Wilmshurst P, Walsh K, Morrison L. Transcatheter occlusion of foramen ovale with a buttoned device after neurological decompression illness in professional divers. Lancet 1996;348:752–753.
12. Walsh K, Wilmshurst PT, Morrison WL. Transcatheter closure of patent foramen ovale using the Amplatzer septal occluder to prevent recurrence of neurological decompression illness in divers. Heart 1999;81:257–261.
13. Wilmshurst P, Nightingale S, Walsh KP, et al. Effect on migraine of closure cardiac right-to-left shunts to prevent recurrence of decompression illness, stroke or for haemodynamic reasons. Lancet 2000;356:1648–1651.
14. Keppeier P, Rux S, Dirks J, et al. Transcatheter closure of 100 patent foramina ovalia in patients with unexplained stroke and suspected paradoxic embolism: A comparison of five different devices [Abstr]. Eur Heart J 1999;20:196.
15. Braun MU, Fassbender D, Schoen SP, et al. Transcatheter closure of patent foramen ovale in patients with cerebral ischemia. J Am Coll Cardiol 2002;39:2019–2025.
16. Han Y, Gu X, Titus JL, et al. New self-expanding patent foramen ovale occlusion device. Catheter Cardiovasc Interv 1999;47:370–376.
17. Rao PS. Transcatheter closure of atrial septal defects with right-to-left shunts. In: Rao PS, Kern MJ (eds). Catheter Based Devices for the Treatment of Noncoronary Cardiovascular Disease in Adults and Children. Philadelphia: Lippincott, Williams & Wilkins. 2003, pp.119–128.
18. Yalonetsky S, Schwartz Y, Lorber A. Analysis of left and right ventricular Doppler tissue imaging in patients undergoing percutaneous closure of patent foramen ovale. J Invasive Cardiol 2007;19:252–254.
19. Eyskens B, Ganame J, Claus P, et al. Ultrasonic strain rate and strain imaging of the right ventricle in children before and after percutaneous closure of an atrial septal defect. J Am Soc Echocardio 2006;19:994–1000.
20. D'hooge J, Heimdal A, Jamal F, et al. Regional strain and strain rate measurements by cardiac ultrasound: Principles, implementation and limitations. Eur J Echocardio 2000;1:154–170.
21. Gilman G, Khandheria BK, Hagen ME, et al. Strain rate and strain: A step-by-step approach to image and data acquisition. J Am Soc Echocardio 2004;17:1011–1120.
22. Andersen NH, Terkelsen CJ, Sloth E, Poulsen SH. Influence of preload alterations on parameters of systolic left ventricular long-axis function: A Doppler tissue study. J Am Soc Echocardio 2004;17:941–947.
23. Di Salvo G, Pacileo G, Caso P, et al. Strain rate imaging is a superior method for the assessment of regional myocardial function compared with Doppler tissue imaging: A study on patients with transcatheter device closure of atrial septal defect. J Am Soc Echocardio 2005;18:398–400.