At the time of admission, she was having class III dyspnoea on exertion and palpitation.  Clinical examination showed heart rate of 90/minute, and a blood pressure of 110/60 mmHg.  There was a pan systolic murmur at the apex and early diastolic murmur at aortic area.  She was afebrile and there were no stigmata of infective endocarditis.  Transthoracic echocardiogram (TTE) showed severe mitral regurgitation and moderate aortic regurgitation.  There was a large pseudo aneurysm arising from mitral-aortic intervalvular fibrosa (MAIVF), seen as an expansible cavity posterior to aortic valve in the parasternal long axis view.  A transoesophageal echocardiogram (TEE) was done to clearly define the aneurysm prior to surgery.  TEE showed large psuedoaneurysm of MAIVF measuring 66 x 46 mm at systole (Figure 1).  Aneurysm showed typical systolic filling and diastolic collapse (Figure 2).  Aneurysm was seen rupturing into left atrium.  Doppler study showed severe mitral regurgitation and moderate aortic regurgitation.  There was a systolic mosaic colour high velocity get originating from the aneurysm into the left atrium causing supra annular mitral regurgitation (Figure 3).
             
              Doppler study showed maximum filling of aneurysm in the isovolumetric contraction phase and absence of flow during diastole due to complete collapse of the aneurysm.  Echocardiogram findings were confirmed during surgery.  Aortic and mitral valves were replaced.  Aneurysm was excised and the defect in the MAIVF was repaired with a

1. Abscess ruptures with slow seepage of blood and expands slowly to form a psuedoaneurysm of left ventricular outflow tract.  The aneurysm can remain unruptured.
2. Abscess forms a psuedoaneurysm, which ruptures into pericardium causing cardiac tamponade.
3. Abscess forms a psuedoaneurysm, which ruptures into left atrium or posterior aortic wall.
4. Abscess ruptures directly into left atrium forming left ventricular- left atrial connection.

Various other complications were also described with aneurysm of MAIVF.  Thrombus can form inside the aneurysm, which can lead to embolisation and stroke7.  There are multiple case reports of large aneurysm of MAIVF

causing systolic compression of coronary arteries producing angina8,9.  Subsequently angiography detected systolic compression of left main coronary artery, left anterior descending artery or left circumflex coronary artery in these patients.  Rupture of aneurysm into left atrium causing atrial septal defect with left to right shunt also has been reported10.  Aneurysm can also cause severe mitral regurgitation by systolic compression of mitral valve11 and can erode into chest wall12.
Echocardiogram:
                   Aneurysm of MAIVF can be detected by transthoracic echocardiogram by the location immediately behind the aortic root.  It has the typical systolic expansion and diastolic collapse, which indicates that it is continuous with left ventricle.  The aneurysm is continuous with left ventricle and it protrudes in to left atrium.  Hence during systole, pressure inside the aneurysm keeps it expanded into the left atrium.  During diastole left atrial pressure is more that the left ventricular pressure and the aneurysm collapses. If the aneurysm has ruptured in to left atrium, there can be a diastolic flow from left atrium to aneurysm mimicking aortic regurgitation.  In these cases doppler examination can show a flow from left ventricle to left atrium during systole causing supra annular mitral regurgitation.  If the aneurysm is smaller in size or if there is a small perforation of MAIVF, transthoracic echo may not clearly show the origin of the eccentric jet.  Many a time trans esophageal echocardiogram will be required for the complete evaluation.  This complication should be diagnosed before surgery, because in addition to the valve surgery; direct surgical repair of the defect also will be required for the long-term survival of the patient.
                 Aneurysm of MAIVF extends into a plane bounded posteriorly by left atrium, anteriorly by aortic root and pulmonary artery and superiorly by pericardium.  Due to its posterior location, it may not be visualized clearly with transthoracic echocardiogram and even may not be readily identified at surgery.  Afridi et al published the largest series of aneurysm of MAIVF and compared the sensitivity of trans thoracic and trans oesophageal echocardiogram in detecting them with respect to intraoperative findings14.  Out of 16 patients with psuedoaneurysm of MAIVF, transthoracic echo could diagnose only 6 (43%) while TEE could detect all.
                      Karalis et al studied 55 patients with aortic valve endocarditis with TEE to find out the incidence of sub aortic complications and to examine the utility of TEE in detecting them14.  24 patients (44%) had involvement of sub aortic structures including 4 with abscess of MAIVF, 4 with aneurysm of MAIVF, 7 with perforation of MAIVF into LA, 2 with aneurysm of AML and 7 with perforation of AML.  TTE could detect only 21% of these complications. Differential diagnoses of aneurysm of MAIVF are aortic root abscess, aorto left ventricular tunnel, dissecting aneurysm of aorta and aneurysm of sinus of Valsalva.  In these conditions marked parallel widening of anterior and posterior aortic wall is typically seen which persists through out the cardiac cycle15.  One case of aneurysm of sinus of Valsalva was reported in the literature, which showed typical systolic expansion and diastolic collapse, but the diagnosis was not confirmed either by echocardiogram or surgically16.  During cath angiography aneurysm of valsalva opacifies during diastole or late systole while aneurysm of MAIVF fills by contrast during early systole.  Ring abscess are usually smaller and non pulsatile.  Abscess is situated at the level of aortic annulus and extends into ascending aorta.  Through out the cardiac cycle, aortic pressure is higher compared to surrounding structures like right ventricle, left

atrium and pulmonary artery. Hence abscesses lack marked pulsatility.  They show systolic and diastolic flow.  Also septations may be seen in the aortic ring abscess.  Differential diagnoses of rupture of aneurysm of MAIVF into left atrium are perforation of AML and rupture of sinus of Valsalva into left atrium.
Management:
                  Natural history of aneurysm of MAIVF is unknown.  Longest survival reported is up to 4 years, in a patient with a small aneurysm 17.  There are no guidelines for the surgical management of these patients.  As rupture of aneurysm into pericardial cavity or left atrium can be lethal, generally patients are advised immediate surgical correction.  Those patients who are not willing for surgery can be monitored periodically by TEE.  There is one report of percutaneous closure of aneurysm of MAIVF in a 69 years old lady who developed this complication seven years after aortic valve replacement18.  There was no evidence of infective endocarditis.  The aneurysm was closed using 12mm Amplatzer muscular VSD occluder device.

Conclusion:
The incidence of sub aortic complications after aortic valve endocarditis is as high as 44%14.  Transoesophageal echocardiogram should be used in these patients for the complete evaluation of sub aortic structures.  Complications like aneurysm of MAIVF need surgical correction in addition to valve replacement.

Acknowledgement:

We acknowledge our gratitude to Ms. Sujatha K and Ms. Sonali B for the secretarial help and to Mr. Paaryuma for the assistance with photography.

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