Eur J Echocardiography (2004) 5, 68e71

Anatomical basis for acquired intracardiac shuntpostaortic valve replacement: Dopplerechocardiographic diagnosis

S. Al Ahmari, J. Malouf, F. Al Atawi, H. Schaff, K. Chandrasekaran)

Cardiovascular Division, Echocardiography Laboratory, Mayo Clinic, 200 First Street SW,Gonda 6-138 NW, Rochester, MN 55905, USA

Abstract We report a case of postoperative intracardiac shunts across the mem-branous septum detected by Doppler echocardiography and discuss the anatomicalbasis for the development of such a complication.ª 2003 The European Society of Cardiology. Published by Elsevier Ltd. All rightsreserved.

Iatrogenic intracardiac shunts are uncommon andhave been recognized after aortic and mitral valvesurgery.2e5 The early detection and treatmentof such a complication can prevent subsequentadverse hemodynamic effects and long-term se-quelae.1,6 We report a case of intracardiac shuntsfrom the left ventricle outflow tract (LVOT) acrossthe membranous septum into the right atrium(RA), right ventricle (RV) and left atrium (LA) fol-lowing a redo aortic valve replacement. The lesionwas detected by transthoracic Doppler echocardi-ography (TTDE).

Case report

An 82-year-old male who had undergone a coronaryartery bypass and tissue aortic valve replacementin 1997, followed by mitral valve annuloplasty in

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1525-2167/$30 ª 2003 The European Society of Cardiology. Publisdoi:10.1016/S1525-2167(03)00040-4

1998, was treated for uncomplicated infective en-docardities (IE) in February 2000 with prolongedantibiotic course and in June 2002 he was evaluat-ed for exertional shortness of breath. He deniedorthopnea, nocturnal dyspnea, or fevers. Physicalexamination of this afebrile elderly patient wasunremarkable except for a 3/6 ejection systolicmurmur over the aortic area radiating to the caro-tids and a holodiastolic murmur along the rightsternal border. There was no peripheral stigma ofIE. Laboratory results were normal. ECG revealedsinus rhythm, first-degree heart block and an oldinferior infarct. Transthoracic echocardiogramshowed moderately enlarged left ventricle withdecreased systolic function, EF 35%. The aortic tis-sue valve was thickened, with decreased cusp ex-cursion and without obvious vegetation or flail.Color flow Doppler demonstrated severe prostheticregurgitation. The degree of regurgitation hasincreased from moderate to severe compared toprevious examination. The estimated pulmonarysystolic pressure was 61 mmHg. The patientunderwent aortic valve replacement with a 23

hed by Elsevier Ltd. All rights reserved.

Anatomical basis for postaortic valve replacement 69

Carpenteer Edwards tissue valve, and the post-operative course was uneventful. Transthoracicechocardiogram performed prior to dischargeshowed improved LV function with an EF of 50%,and normal function of the aortic tissue prosthesis.However, there was a highly turbulent color flowjet from the LVOT across the membranous septuminto the RA and RV straddling the septal leaflet ofthe tricuspid valve on the parasternal short-axisview (Fig. 1). The peak velocity of the jet, fromthe LVOT to RA, was 6 m/s (Fig. 2). In the apicalfour-chamber view another jet was seen enteringthe LA from the LVOT just beneath the aortic pros-thesis (Fig. 3). The RV was not enlarged and theDoppler estimated RV systolic pressure was 46mmHg. The calculated shunt fraction was not sig-nificant (QP/QS ratio of 1.2). The patient was dis-charged with instruction for early follow up.

Discussion

The congenital form of LV to RA communication ac-counts for less than 1% of all congenital heart dis-ease and was first classified by Gerbode et al.7

Acquired communications are recognized as a com-

plication of IE, myocardial infarction and cardiactrauma8e10 and albeit far less frequently, as com-plication of aortic or mitral valve surgery. Jacksonet al. reviewed a series of 310 patients with aorticvalve replacement and found two cases of postop-erative iatrogenic shunts.6 Both patients devel-oped heart failure, one at 6 months and theother at 1 year and were found to have intracardi-ac shunts on cardiac catheterization. Similar obser-vation of a membranous defect following aorticvalve replacement havebeen reportedat autopsy.11

The membranous portion of the ventricular sep-tum is intricately related to aortic, mitral, and tri-cuspid valves in addition to RA, right and leftventricles.12 The thin membranous septum, whichis about 3 mm in thickness, lies posterior to theaortic root (non-coronary cusp), and to the leftventricular outflow tract. The septal leaflet ofthe tricuspid valve straddle the right side of themembranous septum dividing it into two portions,superior atrioventricular and inferior inter-ventric-ular portions. The atrioventricular portion is be-tween the RA and left ventricular outflow tract(LVOT) and the inter-ventricular portion is be-tween the two-ventricle (Fig. 1). The membranousseptum separates the aortic root and the LVOTon one side and the RA and RV on the other

Figure 1 (A) Parasternal short-axis view showing two jets straddling the septal leaflet of the tricuspid valve (TV), oneinto the RA and one into the RV. (B) Cross-sectional anatomy of the membranous septum (MS) denoted by the twoasterisks at the level of the LVOT where it is divided into superior atrioventricular (AV) and inferior inter-ventricular(IV) portions.

70 S. Al Ahmari et al.

Figure 2 (A) Color flow Doppler from the apical four-chamber view showing an eccentric jet from the LVOT into RAdirected toward the right atrial free wall. (B) CW Doppler demonstrates a peak velocity of the LVOTeRA systolic shuntto be 6 m/s.

Figure 3 (A) Color flow Doppler from the apical four-chamber view showing the two shunts into the LA (arrowhead)and into the RA (arrow). (B) Anatomy of the membranous septum (between the two asterisks) divided by the septalleaflet of the tricuspid valve into superior atrioventricular (AV) and inferior inter-ventricular (IV) portions.

Anatomical basis for postaortic valve replacement 71

side. This anatomical arrangement explains thedevelopmental course of fistula communicationfrom the LVOT to either RV or RA or from the aorticroot to the RV. Additionally, the membranous partof the ventricular septum lies posterior to theposteromedial commissure of the mitral valve ad-joining the LA. During aortic or mitral valve sur-gery, aggressive debridement of calcific aortic ormitral valve annuli, and in some cases, inclusionof the septum in the suture line, may result in in-jury causing ischemic necrosis and gradual weak-ening of the septum and formation of fistulae.13,14

The clinical presentation may vary based on themagnitude of the shunt. Large shunts are associat-ed with failure of hemodynamic improvement im-mediately after aortic or mitral valve surgery.1

Small shunts, as in our case, are initially asympto-tic and the associated murmur may be the onlyclue. Progressive enlargement of the defect withthe resultant increase in shunt may lead to heartfailure weeks or months after surgery.6 With thewide application of intraoperative echocardiogra-phy these defects can be diagnosed promptly.While the communication into RA or LA can be de-tected easily, the communication into anteriorlylocated RV can be at times difficult to image dueto the intervening aortic prosthesis. The two-di-mensional echocardiogram may show the fistuloustract if it is large, whereas color Doppler will in-variably show the left to right shunt and the spec-tral Doppler can estimate the systolic gradient.The color Doppler jet from the LVOT to RA shouldbe differentiated from an eccentric tricuspid re-gurgitation jet. The tricuspid regurgitation usuallyhas a lower peak velocity unless there is severepulmonary hypertension, whereas the shunt fromLVOT to RA will usually be higher and directed to-ward the right atrial free wall. The hemodynamicconsequences of significant shunts are readily de-termined by the surface echocardiography and in-clude the assessment of RV size and function.Determination of shunt fraction and pulmonary ar-tery pressure will quantify the hemodynamic bur-den on the pulmonary circulation. Obtaining thisinformation from an echo obviates the need forcardiac catheterization indicated in early casereports.2,6,13

Surgical trauma to membranous septal tissue,already weakened from previous valve operations

and previous IE, rendered our patient susceptiblefor developing this complication. Since the patienthad no symptoms and the shunt was not signifi-cant, conservative management with bacterial en-docarditis prophylaxis and frequent clinical andechocardiographic monitoring was decided.

References

1. Galbraith JO, Murphy M, Read R, et al. Left ventricleerightatrial shunt: an unusual cause of hemodynamic deteriora-tion following aortic valve surgery. J Thorac Cardiovasc Surg71:383e5.

2. Silverman NA, Seti GK, Scott SM. Acquired left ventricu-lareright atrial fistula following aortic valve replacement.Ann Thorac Surg 1980;30:482e6.

3. Benisty J, Roller M, Sahar G, et al. Iatrogenic leftventriculareright atrial fistula following mitral valve re-placement and tricuspid annuloplasty: diagnosis by trans-thoracic and transesophageal echocardiography. J HeartValves 2000;9:732e5.

4. Seabra R, Ross DN, Lavin GL. Iatrogenic left ventricleerightatrial fistula following mitral valve replacement. Thorax1973;28:235e41.

5. Weinrich MW, Graeter T, Langer F, Schafers H. Leftventriculareright atrial fistula complicating redo mitralvalve replacement. Ann Thorac Surg 2001;71:343e5.

6. Jackson DH, Murphy GW, Stewart S, et al. Delayedappearance of left to right shunt following aortic valvularreplacement. Report of two cases. Chest 1979;75:184e186.

7. Gerbode F, Hultgren H, Melrose D, et al. Syndrome of leftventricleeright atrial shunt: successful surgical repair ofdefect in five cases with observation of bradycardia onclosure. Ann Surg 1958;148:433e6.

8. Sadiq M, Sreeram N, Giovanni J, et al. Endocarditis withmultiple intracardiac shunts: identification and repair. AnnThorac Surg 1995;59:753e5.

9. Hole T, Wiseth R, Leaving O. Post-infarction left ventricle toright atrial fistula diagnosed by transthoracic Dopplerechocardiography. Eur Heart J 1995;16:866e8.

10. Dunseth W, Ferguson TB. Acquired cardiac septal defect dueto thoracic trauma. J Trauma 1965;5:142e9.

11. Roberts WC, Bulkley BH, Morrow AG. Pathologic anatomy ofcardiac valve replacement: a study of 224 necropsiespatients. Prog Cardiovasc Dis 1973;15:539.

12. Edwards JE, Burchell HB. The pathological anatomy ofa deficiency between the aortic root and the heart,including aortic sinus aneurysms. Thorax 1957;12:125.

13. Lorenz J, Reddy CV, Khan R, et al. Aortico-right ventricularshunt following aortic valve replacement. Chest 1983;83:922e5.

14. Timmis CC, Gordon S, Rarvi SA. Iatrogenic atrial septaldefect: an unusual complication of valvular heart surgery.Am Heart J 1972;83:804e9.