A Rare Case of Mitral Prosthesis Dislocation Due to a Circumferential Left Atrial Dissection

Abstract

Left atrial dissection is a rare entity mostly associated with mitral valve surgery and revealed in early post-operative period. This case report discusses a case of left atrial dissection associated with dislocation of the mechanical mitral prosthesis in the left atrium, which was peculiar in its anatomy and pathophysiology, occurred 12 years after surgery. (Level of Difficulty: Advanced.)

Central Illustration

Introduction

Left atrial dissection (LAtD) is defined as the forced separation of left atrial (LA) wall layers by blood creating a new chamber from the mitral annulus to the LA free wall or interatrial septum, with or without communications into the true LA. It is a rare complication of cardiac surgery and it is most commonly associated with mitral valve (MV) surgery (1), although other etiologies have also been defined (2). We describe the first case of circumferential LAtD with dislocation of the mechanical mitral prosthesis (MP) in the LA, without paravalvular leak, that occurred 12 years after surgery.

Learning Objectives

• •To review all causes of circumferential LAtD with different presentation.
• •To recognize the imaging findings of circumferential LAtD.

History of Presentation

An 81-year-old woman was admitted to our hospital for heart failure and new onset of atrial flutter. She was afebrile, with a pulse rate of 140 beats/min, blood pressure of 110/70 mm Hg, and arterial oxygen saturation of 95%. On clinical examination we found rhythmic, paraphonic heart sounds, with vesicular breath sounds reduced, and a mild leg swelling.

Past Medical History

The patient has a history of hypertension; moderate mitral calcific stenosis and regurgitation; and moderate tricuspid regurgitation, treated with MV replacement with MP (no. 31; St. Jude Medical, St. Paul, Minnesota); tricuspid valve annuloplasty (ring MC3 no. 28; Edwards Lifesciences, Irvine, California); radiofrequency ablation of atrial fibrillation; and LA appendage closure, 12 years before the present admission (Central Illustration). The post-operative transthoracic echocardiography (TTE) showed normal functioning MP without leakage. The previous TTE, performed a year before, showed well-seated normal functional prosthetic valve and a moderate aortic stenosis. She reported worsening dyspnea and fatigue over the past month.

Central Illustration.

Timeline From Mitral Valve Replacement Through Rehabilitation

HF = heart failure; LA = left atrium; LV = left ventricle; TTE = transthoracic echocardiogram.

Differential Diagnosis

Prosthetic dysfunction, worsening of aortic stenosis, heart failure with preserved or reduced ejection fraction were the main hypotheses to explain symptoms.

Investigations

At the admission, laboratory tests showed hemoglobin 8.2 g/dl and normal values of inflammatory markers. The chest x-ray showed interstitial-alveolar pulmonary edema. TTE evaluation (Figures 1 and 2, Video 1), showed a dislocation of MP in LA 2.5 cm above the annular plane with normal excursion of moving elements. The transesophageal echocardiographic 2-/3-dimensional analysis confirmed the dislocation due to a circumferential LAtD starting from the annulus (Figures 3 and 4, Videos 2 and 3). The resulting LA was enlarged with the posteroinferior atrial wall tendency to aneurysmal dilatation, and a false lumen between the atrioventricular junction and the MP was dislocated. The endocardial layer appeared as a flap structure to which the MP was anchored (Figure 5, Video 4); moreover, the prosthesis was functioning without paravalvular leakage. Ultrasound examinations showed a normal size left ventricle (48 mm), moderate hypertrophy (13 mm), and normal fraction ejection (55%). There was also severe aortic stenosis (aortic valve area 0.6 cm²/m²) with mild aortic regurgitation.

Figure 2.

Transesophageal Echocardiography 4-Chamber View

Transesophageal echocardiography 4-chamber view: MP dislocation in left atrium. TV = tricuspid valve; other abbreviations as in Figure 1.

Figure 1.

Transthoracic Echocardiography Parasternal View

Transthoracic echocardiography parasternal view: mitral prosthesis (MP) dislocation 2.5 cm above atrioventricular junction (AVJ). 2D = 2-dimensional; AO = aorta; LV = left ventricle.

Figure 3.

Transesophageal Echocardiography Transgastric View

Transesophageal echocardiography transgastric view: MP dislocation 2.5 cm above AVJ. FL = false lumen; other abbreviations as in Figures 1 and 2.

Figure 4.

3-Dimensional Transesophageal Echocardiography 2-Chamber View

Three-dimensional Transesophageal echocardiography 2-chamber view: circumferential FL between AVJ and MP. AW = atrial wall; RV = right ventricle; other abbreviations as in Figures 1, 2 and 3.

Figure 5.

Transesophageal Echocardiography 2-Chamber View

Transesophageal echocardiography 2-chamber view: flap structure to which MP was anchored. Abbreviations as in Figures 1, 2 and 3.

Management

The patient was transferred to the Cardiac Surgery Department where she underwent surgery despite the high operative risk (EuroSCORE [European System for Cardiac Operative Risk Evaluation] II: 12.8%). At surgical examination (Video 5) the MP dislocation, LAtD, and LA wall dissection were confirmed. After explantation of the mechanical valve, a bioprosthesis was implanted (Hancock II no. 27; Medtronic, Minneapolis, Minnesota) with multiple Teflon-reinforced stitches passed through the native annulus and the aneurysmal neck therefore eliminating the false atrial aneurysm. Consequently the aortic valve was replaced with a sutureless Perceval L bioprosthesis (LivaNova, London, United Kingdom). Blood cultures were negative and post-operative transesophageal echocardiographic revealed normal left ventricular and prosthesis function (Video 6).

Discussion

The incidence of LAtD is 0.16% after cardiac surgery, of which 56% of cases occur after MV surgery (2). LAtD in mitral surgery can have different etiology; moreover, severe calcification of the annulus may be contributory (3). LAtD is also reported after blunt trauma, cardiac amyloidosis, percutaneous procedures, myocardial infarction, radiofrequency ablation, and infective endocarditis (2). Spontaneous dissection of the LA has been rarely described (4).

Partial atrioventricular separation is the probable pathogenesis of LAtD associated with MV procedures, although nonmitral cardiac surgeries can cause a LAtD because of the creation of a small entry tear in the LA endocardium: the initial insult allows the pressurized blood to create the dissection within the wall. Possible mechanisms suggested (5) in MV surgery are aggressive debridement of the annulus, prosthesis oversizing, inappropriate suturing, or intense traction applied on the annulus that can cause laceration or bleeding from the atrioventricular junction. However, tissue fragility, infection, and necrosis were also suggested. The time of presentation of LAtD may be early or delayed, ranging from immediately intraoperative to 20 years after the procedure. Only 16.9% of patients show a late presentation (2).

In our case, LAtD appeared 12 years after MV replacement, with a subacute presentation: heart failure symptoms and atrial flutter with hemodynamic stability.

Contributing factors to the process are an aggressive debridement of calcified native MV during the first operation, the tissue fragility associated with the previous radiofrequency ablation procedure, and the old age. In our case, the increase in afterload due to aortic stenosis led to a greater systolic expansion with leakage of blood into the LA wall causing dissection (6). The MP was also placed with everting pledgeted sutures, a technique described in other cases of LAtD after MV replacement (7,8). These would be a point of minor resistance and may have been a contributory causal factor of the process. The patient had no evidence of recent active infection; however, an undetected low virulence infection may have played a role even months before.

The spectrum of LAtD presentation depends on the extent of atrioventricular junction injury disruption and the direction of the dissecting blood: in the published reports, surgical treatment has been used in majority of patients (8) because LAtD may evolve in acute exsanguinating hemorrhage, hematoma, or prosthesis leak or may encroach onto the adjacent structures and can progress toward occlusion of LA cavity, pulmonary veins or mitral inflow obstruction, pulmonary artery hypertension, and right heart failure. There are case reports describing acute LAtD after MV replacement surgically treated for their hemodynamic instability, as well as cases of deferred surgery for paravalvular leak with progression to heart failure (7,9,10). Wu et al. (10) described a chronic LAtD revealed a week after surgery and subjected to regular follow-up for high risk of reoperation. It was associated to perivalvular leakage and increased in size at 12-year follow-up, worsening the patient’s condition. TTE showed a large mitral periprosthetic defect and communication with the LAtD; LA received blood during left ventricular systole and returned back to the left ventricle during diastole (Figure 6A). Our case is the first report of a complete circumferential LAtD with MP dislocation without paravalvular leak (Figure 6B), despite the fact that in published reports it most frequently occurs along the posterior wall of the LA (7).

Figure 6.

Posterior and Circumferential Left Atrial Dissection

The schematics show posterior (A) and circumferential (B) left atrial dissection.

Follow-Up

The patient was discharged 7 days after the surgery in stable conditions. At her 3-month follow-up, her transesophageal echocardiograph did not show recurrence.

Conclusions

This case report presents key differences to previous reports. The patient underwent high-risk reoperation for high risk of progression of dissection and flap rupture, electrical instability due to LA wall stretch and heart failure, with excellent results observed anatomically and clinically, despite old age.

Funding Support and Author Disclosures

The authors have reported that they have no relationships relevant to the contents of this paper to disclose.

Appendix

Supplemental Video 1

TTE 4-Chamber View

Supplemental Video 2

2D TEE Longitudinal Transgastric

Supplemental Video 3

3D TEE

Supplemental Video 4

2D TEE 2-Chamber View

Supplemental Video 5

Surgical Intervention

Supplemental Video 6

Post-Operative TEE