Haemodynamic improvement of older, previously replaced mechanical mitral valves by removal of the subvalvular pannus in redo cardiac surgery Free

INTRODUCTION

After mechanical mitral valve replacement, other diseased heart valves may require surgery. Marked pannus may form along the upper and lower ring planes of previously placed mechanical mitral valves. Although the valve leaflet motion may not be impeded, the pannus may aggravate valve gradients and areas [1]. In redo cardiac surgery for other diseased heart valves, pannus removal from mechanical mitral valves may improve the valve haemodynamic function.

CASE REPORTS

Four women (age, 57–67 years) who had mechanical mitral valve replacement with posterior chordal preservation 20–29 years earlier underwent redo cardiac surgery to treat other diseased heart valves (Table 1). The older mitral valves worked well in all patients without any impaired bileaflet motion.

Under moderate hypothermic cardiopulmonary bypass and cardioplegic cardiac arrest, pannus was removed from mechanical mitral valves through aortic valve openings and left atriotomies. Pannus evaluation was through the left atriotomy, which showed calcified circular pannus protruding 1.0–2.0 mm into the lower margin of the valve metal ring opening (Fig. 1) and less pannus present on the upper plane of the ring. In 3 patients who required aortic valve replacement, the aortic valve was removed and the subvalvular pannus inside the mitral valve ring was pushed from the atrial to ventricular side and removed through the aortic opening using small sinus forceps. In the patient who had tricuspid valve repair, pannus was removed through the previously replaced bileaflet mechanical aortic valve opening. Although 2 patients had normal mitral valve gradients, the marked pannus growth inside the mitral valve ring led to concern about possible valve malfunction. At 3–19 months after surgery, echocardiography showed that mitral valve areas increased 0.1–0.6 cm² with decreased maximum and mean valve pressure gradients (Table 1).

Figure 1:

(A) Subvalvular pannus (arrow) around mechanical mitral valve, visible through the aortic valve opening (arrowhead) after aortic valve excision. (B) Subvalvular pannus ring included an inner calcified sharp ring (arrowheads) and an outer hard fibrotic ring (arrows).

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DISCUSSION

Prosthetic mechanical valve dysfunction caused by valve thrombosis or pannus formation often requires mitral valve replacement [1, 2]. However, because mechanical valves have not substantially changed over the past two decades, pannus removal instead of valve replacement may be prudent to recover prosthetic mitral valve function [3].

Subvalvular pannus protruding into the valve opening may progressively grow into the valve opening, aggravating valve haemodynamics [4] or limiting leaflet motion [2–4]. For patients requiring redo surgery for valves other than the mitral valve, the older mechanical mitral valves that are hindered by pannus could be replaced. However, in patients requiring continuous anticoagulation, pannus removal alone can improve the valve haemodynamic function, reducing the possibility of future mechanical valve malfunction and the morbidity and mortality associated with redo mitral valve replacement.

Funding

Supported by funding from the Clinical Research of Chonbuk National University and the Biomedical Research Institute of Chonbuk National University Hospital.

Conflict of interest: none declared.

REFERENCES