CONGENITAL HEART DISEASE

     CONGENITAL HEART DISEASE  - A        CONGENITAL HEART DISEASE - B

     CONGENITAL HEART DISEASE  - C        CONGENITAL HEART DISEASE - D

     CONGENITAL HEART DISEASE  - E      

  CONGENITAL HEART DISEASE  - C

TRANSCATHETER CLOSURE OF SECUNDUM ATRIAL SEPTAL DEFECTS IN CHILDREN AND ADULTS

Dr. Assad Al Hroob* Pediatric Cardiology Section, Department of Cardiology and Cardiovascular Surgery, Hamad Medical Corporation, Doha, Qatar

   ABSTRACT

   Introduction

   Atrial septal defects in children

   Adults with secundum atrial septal defect or patent foramen ovale

   Adults with patent foramen ovale and stroke/ transient ischemic attack

   Adult patients with atrial septal defect and pulmonary hypertension
   Pregnant women with atrial septal defect
   CONCLUSION
   References
   THE SNAKE, THE FARMER, AND THE HERON

ABSTRACT

Surgical treatment of atrial septal defect is well established. With the advances in transcatheter therapy, closure of septal defects in the catheterization laboratory has also been introduced using various type of devices. These devices have been subjected to extensive clinical trials to evaluate their safety and appropriateness in children and adult patients. This review outlines the current status of these devices especially the new generation of devices (Amplatzer, Cardio seal, Helix) and the current recommendations for closure of PFO/ASD in children and adults in variable clinical circumstances.

(Heart Views. 2002;3(2):79-83) © 2002 Gulf Heart Association.

Key Words:

   atrial septal defect    patent foramen ovale    transcatheter closure

Introduction

The use of devices for transcatheter closure of atrial septal defects (ASD)s has been tried since the mid 70’s. Many devices have been developed and tested for transcatheter closure with variable degrees of success and acceptance. Variable features were considered in evaluating those devices, mainly ease of implantation, control during the procedure, the ability to retrieve or reposition the device if misplacement occurs prior to release, efficiency of closing the defect and economic competitiveness with surgical closure. The currently available investigational devices are: Star flex, NMT Medical Boston, Angel Wings, Microvana Corp., Cardio Seal, NMT Medical; Helix, WL Gore and Associates; and Amplatzer, AGA Medical. The last three devices are widely used especially the Amplatzer which we have been using at Hamad Medical Corporation (HMC). The Amplatzer device will probably survive the above mentioned qualification variables. With decreased risk of both surgical and transcatheter interventions, the diagnosis of an ASD frequently leads to the need for closure.

The management of ASDs can be variable and depends on the age of the patient or circumstances as well as the size of the defect.

Atrial septal defects in children

The pediatric community no longer argues the need of closure of ASDs in children, but rather debates the existence of holes that are "too small to close". The consensus among the pediatric cardiologists is to observe infants with secondum ASD measuring less than 8 mm since two-thirds may close spontaneously in the first 18 months of life. Children with significant left to right shunt i.e., right atrial enlargement and right ventricular enlargement should be closed at 3 – 5 years of age even if asymptomatic. With the currently available devices, holes as large as 38 mm can be easily closed. Studies using AMPLATZER device (Figure1) showed complete closure in 96% of patients (1-5). All types of shunts could be occluded. It is user friendly, retrievable and there are no major complications (Figures 2-4). The Amplatzer ASD occluder device has been used successfully in our institution. Figures 5,6,7 shows multiple views of a medium size atrial septal defect (pre and post closure) of one of our patients at HMC.

Fig.1

Fig.1. Amplatzer ASD closure device

Fig. 2

ig 2. Shapes of the amplatzer device during the implantation process

Fig. 3

Fig.3. Loading of the device over the delivery system

Fig. 4

Fig.4. Different sizes of the amplatzer device

Adults with secundum atrial septal defect or patent foramen ovale

Improved physician awareness and sophisticated echocardiography equipment have made possible early and accurate diagnosis of ASDs, including small defects that are not hemodynamically significant. Hence, the natural history of ASD in adults has been recently questioned. It has been widely observed that in hemodynamically significant ASDs requiring closure, increasing adult age is accompanied by symptoms and signs of atrial fibrillation, paradoxical embolism and later on pulmonary hypertension (6,7). Current clinical studies differ in their recommendations concerning adults with ASDs (8,9). Shah et al recommend observation or medical treatment in the absence of significant symptoms. However Kostantinits el al (9) showed substantial improvement in long-term survival with surgical ASD closure. A closer look at both studies, however, reveals significant distinction in these two non- randomized retrospective studies: younger mean age (36.2- 38.6 vs 54 – 57 yrs); less symptomatology, (36 – 39% vs 75 – 76%) experiencing dyspnea at study entry or lower pulmonary artery pressure. These differences suggest that in the study of Shah, which found equivalent outcome between medical and surgical therapy, the patients had less severe disease. Gatzoulis (10) et al also found increasing late incidence of atrial fibrillation if ASD closure occurred after age 40, suggesting that delay in closure of ASD might result in increasing long-term morbidity. It is therefore recommended that symptomatic adults with ASDs will benefit from closure. The recommendation is not as clear-cut in the adult without symptoms. However, it is widely accepted that those who present with chronic right ventricular volume overload on echocardiography should be closed regardless of symptoms.

Adults with patent foramen ovale and stroke/ transient ischemic attack

Paradoxical embolism via a patent foramen ovale (PFO) is widely recognized as a potential cause of transient ischemic attack (TIA) and stroke especially in younger patients (11). In one study

Fig. 5

Fig.5. Transthoracic longitudinal subcostal demonstrating A moderate sized ASD

Fig. 6

Fig.6. Transthoracic short axix subcostal view demonstrating Amplatzer device position after release showing both discs and waists covering the defect.

Fig. 7

Fig.7. Transthoracic 4-chamber view with color Doppler after release of ASD device occluder showing good position without residual shunt.

evaluating the frequency with which a PFO may be responsible for stroke, it was found that among those with strokes of undetermined origin (cryptogenic strokes), a patent foramen ovale was much more likely to be present than in those with an identifiable cause of stroke in patients both under and over age 55. The odds ratio of patent foramen ovale in cryptogenic stroke was 7.2 (12). In another study of 197 patients with an embolic stroke, 23 percent had a patent foramen ovale as the only abnormality seen on a transesophageal echocardiogram (TEE); 9.5 percent had deep vein thrombosis diagnosed with venography (13). A right-to-left shunt that is sufficient to result in a paradoxical embolus through a patent foramen ovale is more likely to develop in response to physiologic mechanisms that transiently increase the volume and pressure differences between the right atrium and left atrium, such as the straining phase of the Valsalva maneuver. A transient rise in right atrial pressure above left atrial pressure occurs, reversing the interatrial gradient and inducing a right-to-left shunt (14). Physiologic conditions that are associated with a Valsalva include straining to defecate, lifting or pushing heavy objects, and vigorous repetitive cough (15). When a cerebral event caused by a right-to-left shunt through a patent foramen ovale is suspected, the history should include specific questions that define the circumstances immediately preceding the event. In addition, the Valsalva maneuver should be routinely employed with contrast echocardiography for diagnostic purposes (12,14,15). The subsequent clinical course of an untreated cerebral ischemic event associated with a patent foramen ovale is unknown and therefore the effect of treatment that is designed to prevent further events has not been established. Patients at risk should avoid those maneuvers mentioned that are known to provoke transient right-to-left shunting via a foramen ovale or an ostium secundum atrial septal defect. As per the ACCP recommendations (16), other therapeutic options include: 1) Aspirin or warfarin for several months for a single mild transient ischemic attack if the PFO is sufficiently large to permit a sizable transient right-to-left shunt as demonstrated by contrast echocardiography; 2) Closure of the interatrial communication with surgery or a catheter delivered device, which should be considered if the cerebral events are prolonged, recurrent, or if they are followed by residual neurologic deficit. There are studies that have evaluated the effect of PFO closure on neurologic events. One study examined 91 patients with one or more prior cerebrovascular ischemic events who underwent surgical closure of a patent foramen ovale (17). The overall freedom from an ischemic episode at one and four years was 93 and 83 percent, respectively. Similar results were seen in another report of 80 patients with at least one paradoxical embolic event, including a transient ischemic attack, cerebrovascular accident, or peripheral embolism, who underwent percutaneous closure of a patent foramen ovale using five different devices (18). During a five-year follow-up, the annual risk of a recurrent embolic event was 3.4 percent. Recurrent ischemic episodes, despite intact device closure, may be due to thrombus on the left atrial side of the device. Another study involving 63 patients followed for 2.4 years reported the same results (19). Sievert and colleagues (20) reported similar result with 95.7% at 1 year and 94% at 3 years remaining free from recurrence of TIA, stroke, or peripheral embolism after catheter PFO closure in 281 patients with paradoxical embolism. The diameter of the PFO measured with a balloon catheter ranged from 3 – 24mm., mean of 10 ± 3.5mm. Implantation of the device occluder was technically successful in all patients (seven different devices were used). One patient suffered from septicemia and subsequently died. In 2 patients device embolization occurred during or after the procedure; 37 patients had other minor complications without long-term sequelae. There were no complications observed with the newer devices such as Amplatzer or Helix. These studies provide evidence that catheter PFO closure is technically a simple procedure, especially with the newer devices. With increasing experience, the success rate has improved and the complication rate has decreased. The major advantage of the catheter procedure is the avoidance of life-long anticoagulant treatment.

Adult patients with atrial septal defect and pulmonary hypertension

Patients with pulmonary hypertension represent a unique and evolving entity. Each decade has seen changes in recommendations for interventions and care, which may vary from center to center. This is due largely upon available modalities for testing pulmonary vascular responsiveness to vasomodulatory agents, medications, machines to support the failing right ventricle, and improvements in surgical and anesthetic preoperative technique. Adults with ASDs with a Qp:Qs of ž1.5:1 and pulmonary vascular resistance less than 10–12 indexed wood units and resting systemic arterial oxygen saturation approaching 90% will have an improved intermediate-term survival with ASD closure (21). The results are encouraging even in patients who undergo closure after the age of 50 or 60; the reported survival rates at 5, 10, and 15 years have been 93, 86, and 79 percent, respectively (22,23). Closure of ASD is contraindicated in severe pulmonary vascular disease with resting total pulmonary vascular resistance of ž 12 units.

Pregnant women with atrial septal defect

The hemodynamic “rules of engagement” regarding ASD closure should not be altered for the pregnant female patient. To date, there are no data supporting prophylactic closure of non-hemodynamically significant ASD to prevent or reduce the incidence of paradoxical systemic emboli during pregnancy. Even the extremely low current risk of catheter-based intervention (which include CNS ischemia) appears to outweigh the theoretic risk of paradoxical thromboembolization in such patients. Therefore, at present, for pregnant women with an ASD, the rules guiding the need for intervention should not be altered (24).

 

CONCLUSION

The use of the new generations of transcatheter septal occluders as an alternative to surgical management of atrial septal defects in variable circumstances is a safe, technically simple procedure and effective in complete closure of secundum ASDs including even large defects in the majority of patients. It is more attractive to patients and families especially since a thoracotomy scar is avoided. In addition, in patients with small ASD/PFO, transcatheter closure obviates the need for life-long anticoagulant therapy.

 

References

1. Whight et al, transcatheter closure of secundum atrial septal defect using 
    the Amplatzer septal occluder. Current Intev. Cadiol. Rep. 2000.2: 2 (1) 70-77.

2. Masura et al. Transcatheter closure of ASD using new self-centering 
   Amplatzer septal occluder. Catheterization or cardiovascular diagnosis.
   42; 388 – 393 (1997).

3. Scheider et al. Transcatheter of secondum ASD. 
    Defects with the ASDs device in children. J.Am Coll Card. [Suppl] 1996; 27:119.

4. Das GS et al. Experimental. ASD closure with a new, transcatheter, 
    self-centering device. Circulation. 1993; 88:1754-1764.

5. Sharafuddin MJA et al. Transveneous closure of secondum ASD. 
    Preliminary results with new self- expanding nitinol prosthesis in 
    a siome model. Circulation 1997; 95:2162-2168.

6. Gladwell, Malcolm. The tipping point. How little things can make
     a big difference. Boston: Little Brown Company, 2000.

7. Campbell M, Neill C. et al. The prognosis of ASD.
    Br. Medical J 1957:1; 1375 – 1383.

8. Shah D, Azhar M, et al. Natural history of ASD in adults after medical or surgical treatment. Br. Heart J 1994; 71: 224 – 228.

9. Konstantinides S, et al. A comparison of surgical and medical therapy 
    for ASD in adults. N Eng. J Med. 1995; 333; 469 – 473.

10. Gazelles Moetal. Atrial arrhythmia after surgical closure of atrial septal defects
      in adults. N Engl. J Med. 1999; 340: 839 – 846.

11. Falk V et al. Trapped thrombus in a patient foramen ovale.
      Thoraco-cardiovascular Surg. 1997; 45: 90 – 92.

12. DiTullio, M, Sacco, RL, Gopal, A, et al. Patent foramen ovale as a risk factor for cryptogenic stroke. Ann Intern Med 1992; 117:461.

13. Lethen, H, Flachskampf, FA, Schneider, R, et al. Frequency of
      deep vein thrombosis in patients with patent foramen ovale and 
      ischemic stroke or transient ischemic attack. Am J Cardiol 1997; 80:1066.

14. Movsowitz, C, Podolsky, LA, Meyerowitz, CB, et al. Patent foramen ovale:
      a nonfunctional embryological remnant or a potential cause of 
      significant pathology?. J Am Soc Echocardiogr 1992; 5:259.

15. Langholz, D, Louie, EK, Konstadt, SN, et al. 
      Transesophageal echocardiographic demonstration of distinct mechanisms for
      right to left shunting across a patent foramen ovale in the absence of 
      pulmonary hypertension. J Am Coll Cardiol 1991; 18:1112.

16. Salem, DN, Daudelin, HD, Levine, HJ, et al. Antithrombotic therapy in
      valvular heart disease. Chest 2001; 119 (S):207.

17. Dearani, JA, Ugurlu, BS, Danielson, GK, et al. Surgical patent foramen ovale closure for prevention of paradoxical embolism-related cerebrovascular ischemic events. Circulation 1999;100(SII):171.

18. Windecker, S, Wahl, A, Chatterjee, T, et al. Percutaneous Closure 
      of Patent Foramen Ovale in Patients With Paradoxical Embolism:
      Long-Term Risk of Recurrent Thromboembolic Events. Circulation 2000; 101:893.

19. Hung, J, Landzberg, MJ, Jenkins, KJ, et al. Closure of patent foramen ovale 
      for paradoxical emboli: intermediate-term risk of recurrent neurological 
      events following transcatheter device placement. 
      J Am Coll Cardiol 2000; 35:1311.

20. Sievert, H and et al. PFO closure in patients with TIA/ Stroke.
      Journal of Interventional Cardiology. 2001; 14(2): 261-266

21. Steele et al). Isolated atrial septal defect with pulmonary vascular obstructive 
      disease Long term follow up. Circulation 1987; 1037 – 1042

22. St John Sutton, M, Tajik, A, McGoon, D. Atrial septal defect in patients aged 
      60 years or older. Circulation 1981; 64:402.

23. Fiore, AC, Naunheim, KS, Kessler, KA, et al. Surgical closure of atrial septal defect 
      in patients older than 50 years of age. Arch Surg 1988; 123:965.

24. Michael et al. Closure of atrial septal defect in adult patient. 
      Journal of Interventional cardiology 2001;14(2): 267-269

THE SNAKE, THE FARMER, AND THE HERON

Correspondence to Dr. Assad Al Hroob, Department of Cardiology and Cardiovascular Surgery, Hamad Medical Corporation, P.O. Box 3050, Doha, Qatar

*Consultant Pediatric Cardiologist, Hamad Medical Corporation, Doha, Qatar

Presented at the Minisymposium on Atrial Septal Defect, Department of Cardiology & Cardiovascular Surgery, Hamad Medical Corporation, Doha, Qatar, 7 January 2002.