(Circulation. 1996;94:247-248.)
© 1996 American Heart Association, Inc.
Articles |
the Division of Cardiology, Children's Heart Institute, Children's Hospital, San Diego, Calif.
Correspondence to John W.M. Moore, MD, Director, Cardiology, Children's Heart Institute, Children's HospitalSan Diego, San Diego, 3020 Children's Way, MC5004, San Diego, CA 92123-4282.
Key Words: Fontan procedure catheterization Editorials
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Certainly, Sommer et al have demonstrated that coil occlusion of small fenestrations may be technically feasible. What they have not elucidated, however, are the more important issues: should closure of such fenestrations be performed at all, and if so, is it safe to use Gianturco coils for this purpose?
As background, it is worthwhile to note that a considerable percentage of small fenestrations close spontaneously. In Sommer's series, 4 of 14 patients had spontaneous closure. It is also interesting to discover the occasional patient who after closure of a fenestration with a septal occluder has required repeated placement of a fenestration (J.E. Locke, unpublished data, 1996). Thus, it may be prudent to pause and consider whether patients who require fenestration to successfully negotiate the postoperative period will follow an appropriate course without further intervention.
Sommer and others2 3 4 5 have provided essentially two justifications for transcatheter closure of fenestrations. First, elimination of cyanosis from right-to-left shunting through the fenestration has the potential benefit of improving exercise performance. Unfortunately, many of the acute data,4 including Sommer's, argue to the contrary. Sommer's patients uniformly showed decreases in both cardiac output and tissue oxygen delivery during test fenestration occlusion before coils were deployed. Given these hemodynamic data, one wonders whether the parental reports of increased activity levels in these patients are objective. Second, closing the fenestration also eliminates passage of thrombi into the left heart, thereby potentially reducing the risk of stroke and other adverse embolic phenomena. The issue of thromboembolism in particular needs further evaluation.
With the configuration of the right heart and the sluggish character of right-sided flow after Fontan surgery, it is surprising that thromboembolism only recently has become a major focus of attention. Several reports5 6 7 8 9 10 have shown that thromboembolic complications are relatively common (they occur in up to 20% of patients) and that the manifestations are varied and often life-threatening (they include partial or complete obstruction of the Fontan circuit, stroke, pulmonary embolism, and peripheral embolism). Other than the presence of Fontan physiology, some additional factors have been identified that seem to be related to thromboembolic problems, not the least of which is placement of an occlusion device to close a fenestration or a residual right-to-left shunt (noted in 27% of patients who experienced thromboembolic events in one large series10 ).
Also of concern are pathological studies of septal occlusion devices. Although long-term animal studies have shown full endothelialization after 3 months, short-term specimens have demonstrated the presence of thrombus on the devices.11 12 Moreover, in a report in humans,13 a device that was explanted because of transient ischemic attacks and residual shunting showed failure of full endothelialization and presence of thrombus on the device. Animal studies of Gianturco coils placed in patent ductus arteriosus and other arteries are of even greater concern because short-term studies have shown significant thrombus formation on exposed Dacron strands.14 This, of course, is the purpose of the strands, because thrombus formation (rather than mechanical occlusion) is the mechanism of occlusion by coils.
Thus, on the basis of a small feasibility study, Sommer et al are essentially advocating fenestration closure with a device that stimulates formation of thrombi on both the systemic and the pulmonary venous sides of the Fontan baffle. This recommendation seems premature, given the accumulating concerns about thromboembolic complications and the apparent heightened risk among patients with septal occlusion devices placed in fenestrations. A substantial controlled study with careful follow-up is needed both to demonstrate the safety of using Gianturco coils for this purpose and, from a larger perspective, to demonstrate the hemodynamic or other benefits of nonspontaneous closure.
| Footnotes |
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| References |
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2.
Bridges ND, Lock JE, Castaneda AR. Baffle fenestration with subsequent transcatheter closure: modification of the Fontan operation for patients at increased risk. Circulation.. 1990;82:1681-1689.
3. Kopf GS, Kleinman CS, Hijazi ZM, Fahey JT, Dewar ML, Hellenbrand WE. Fenestrated Fontan operation with delayed transcatheter closure of atrial septal defect: improved results in high-risk patients. J Thorac Cardiovasc Surg.. 1992;103:1039-1048.[Abstract]
4.
Hijazi ZM, Fahey JT, Kleinman CS, Kopf GS, Hellenbrand WE. Hemodynamic evaluation before and after closure of fenestrated Fontan: an acute study of changes in oxygen delivery. Circulation.. 1992;86:196-202.
5. Day RW, Boyer RS, Tait VF, Ruttenberg HD. Factors associated with stroke following the Fontan procedure. Pediatr Cardiol.. 1995;16:270-275.[Medline] [Order article via Infotrieve]
6. Cromme-Dijkhuis AH, Henkens CM, Bijleveld CM, Hillege HL, Bom VJ, Van Der Meer J. Coagulation factor abnormalities as possible thrombotic risk factors after Fontan operations. Lancet.. 1990;336:1087-1090.[Medline] [Order article via Infotrieve]
7. Fyfe DA, Kline CH, Sade RM, Gillette PC. Transesophageal echocardiography detects thrombus formation not identified by transthoracic echocardiography after the Fontan operation. J Am Coll Cardiol.. 1991;18:1733-1737.[Abstract]
8. Jahangiri M, Ross DB, Redington AN, Lincoln C, Shinebourne EA. Thromboembolism after the Fontan procedure and its modifications. Ann Thorac Surg.. 1994;58:1409-1414.[Abstract]
9. Rosenthal DN, Friedman AH, Kleinman CS, Kopf GS, Rosenfeld LE, Hellenbrand WE. Thromboembolic complications after Fontan operations. Circulation. 1995;92(suppl II):II-287-II-293.
10. Fernandes SM, Mayer JE, Burnett JT, Sloss LJ, Landzberg MJ. Thrombosis and thromboembolism in the adult after Fontan surgery. J Am Coll Cardiol. 1996;27(suppl A):44A. Abstract.
11.
Das GS, Voss G, Jarvis G, Wyche K, Gunther R, Wilson RF. Experimental atrial septal defect closure with a new, transcatheter, self-centering device. Circulation.. 1993;88:1754-1764.
12.
Kuhn MA, Latson LA, Cheatham JP, McManus B, Anderson JM, Kilzer KL, Furst J. Biological response to Bard clamshell septal occluders in the canine heart. Circulation.. 1996;93:1459-1463.
13. Prewitt KC, Gaither NS, Farb A, Wortham DC. Transient ischemic attacks after long-term clamshell occluder implantation for closure of atrial septal defect. Am Heart J.. 1992;124:1394-1397.[Medline] [Order article via Infotrieve]
14. Cambier PA, Stajduhar KC, Powell DA, Gomez RR, Virmani R, Farb AJ, Moore JW. Improved safety of transcatheter vascular occlusion utilizing a new retrievable coil device. J Am Coll Cardiol. 1994;(special issue):359A. Abstract.
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