Large Left Ventricular Pseudoaneurysm Presenting After Mitral Valve Replacement

Left ventricular pseudo-aneurysm is a rupture of the cardiac wall tamponated by the pericardium. It can be caused by coronary occlusion, cardiac trauma, endocarditis or it may follow a mitral valve replacement. Mortality, if not treated, is greater than 10% and diagnosis must be supported by imaging investigations. Surgery is often the only choice, at high risk, and it should be planned basing on specic anatomy. Diagnosis of left ventricular pseudo-aneurysm after the replacement of the mitral valve usually occur accidentally; in the case, we presented it was discovered 2 years after the intervention. The patient was treated successfully with planned surgical operation.


Introduction
Left ventricular pseudo-aneurysm (LVP) is a rare and insidious condition, di cult to diagnose and to treat.It is generated by the rupture of the ventricular posterior wall contained by the pericardium, which blocks the bleeding and the consequent cardiac tamponade.Several causes have been described, the most common of which is myocardial infarction of the inferior left ventricle wall.The second most common cause of LVP is surgery, in particular mitral valve replacement, in literature, it is reported in a percentage from 0.02-2% (1).Lesser causes are heart trauma and infections.

Case Presentation
A 61-year-old patient was referred to the Department of Cardiology of our Hospital for the presence of severe exertional dyspnea, NYHA functional class III.Two years before he underwent mitral valve replacement with mechanical prosthesis for the presence of endocarditis leading to severe mitral insu ciency; subsequently about 2 months later the patient had removed the mechanical prosthesis for dysfunction of this (thrombosis), with implantation of a bio-prosthesis Carpentier Edwards 27.The postoperative course was uneventful and the patient was discharged on seventh postoperative day after an echocardiogram that highlighted the correct position and function of the mitral prosthesis.Subsequently, the patient remained asymptomatic for two years, then he began to complain dyspnea, progressively worsened; surface echocardiogram and then a trans-esophageal, demonstrated the correct functioning of mitral bio-prosthesis in presence of a left ventricle pseudo-aneurysm (LVP) of about 6 cm maximum diameter determining a total tele-diastolic volume of 267 ml.Cardiac synchronized multi-detector computed tomography (MDCT) was then useful to better characterize the lesion, and it con rmed the presence of the pseudo-aneurysm, with the neck just adjacent to the edge of mitral prosthesis; the overall size of LVP was 7.6x7.4x6cm.Along the external pro le LVP was demarcated by a scar tissue of about 0.5 cm thick.The neck measured 2.5x2.2cm and was not visible any thrombus inside the LVP, that was close to the right ventricle and right atrium; collaterally, MDCT did not highlight critical coronary disease (Fig. 1).Surgery was then planned, and through a longitudinal median sternotomy, extracorporeal circulation has begun by cannulation of ascending aorta and right atrium by femoral percutaneous vein; the posterior and inferior surface of the heart was cleaved by the surrounding structures after initiating extracorporeal circulation to hold the ventricles.LVP was then opened allowing access to its cavity and visualization from the inside of the neck, which in the cranial portion lay behind the mitral prosthesis.The consistency of the left ventricular wall at the LVP neck has allowed us to perform the implantation of a dacron patch to close it.The patch was sutured with 2 − 0 prolene U-stitches with pledgets in the area adjacent to the mitral prosthesis, while the remaining perimeter was sutured with a 3 − 0 prolene running suture.Successively, LVP external wall was closed covering the patch to complete the hemostasis.The mitral prosthesis appeared in excellent condition con rming that seen in the ultrasound.The patient was easily disconnected from the extracorporeal circulation and the post-operative course was uneventful.A trans-esophageal echocardiogram was performed in ve post-operative day and con rmed the suitable surgical result with the absence of residual pseudo-aneurysm and preserved good shape and global kinesis of the left ventricle.Chest tomography at three months from operation showed a good surgical result (Fig. 2).

Discussion
LVP after replacement of the mitral valve complicates the post-operative course of this intervention at a percentage between 0.02% and 2.0% (1, 2).Several causes may determine a rupture in the posterior wall of left ventricle post-mitral surgery, such as the presence of endocarditis with or without abscess, the need for extensive decalci cation of the annulus, and the placement of a valve oversized.From the few works in the literature on the subject, it emerges that the formation of LVP is facilitated by the presence of coronary heart disease with myocardial infarction (3).LPA after mitral valve replacement usually occurs from a few days to a few weeks after the surgery.In our case, two years have passed between the surgery and the diagnosis of LPA.The onset in our case may have been delayed due to the repeated stress of the mitral valve over a back ventricular wall already weakened.But the rupture may have occurred even shortly after the intervention and then with time the LPA has increased considerably.Due to a poor transthoracic echocardiographic window and the absence of symptoms, the diagnosis may have been delayed.The main symptoms in presence of LVP are dyspnea and chest pain, although in 10% of cases it can be asymptomatic and diagnosis occurs at a post-operative echo (4).There are also changes in electrocardiogram and widening of the cardiac shadow to the chest x-ray, but the instrumental investigations that best allow diagnosis are echocardiography, including trans-esophageal, cardiac tomography or magnetic resonance (MRI) and angiography.The last one represents a method that can be used after the echocardiographic suspect of LVP and allows for a good view of the size of the sac around the left ventricle, the size of the neck, and assess the presence of coronary occlusion.Cardiac tomography and MRI allow you to delimit the contours of LVP and relationships with other cardiac structures, as well as measuring the distance of the neck from the mitral prosthesis (MP).The only therapeutic solution for LVP is represented by surgery, since leaving this untreated would mean a volumetric increase and a 30 to 45% of rupture risk (5).Elective surgery is at high risk, with a mortality ranging from 10-23%, and requires optimal planning based on the characteristics of the pseudoaneurysm.Sternotomy access allows better control of LVP, especially when by large size, and troubles derived from the presence of adhesions.Closure of LVP has been described without opening the cardiac cavities, but suturing the wall from the outside with te on reinforced prolene points (6).Alternatively, Rogers WJ.A composite view of cardiac rupture in the United States National Registry of Myocardial Infarction.J Am Coll Cardiol.1996 May;27(6):1321-6.

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