Teaching Case

An 80-year-old female patient presented with a history of progressive shortness of breath. She had a background of previous rheumatic heart disease complicated by mitral stenosis for which she has had a Star-Edwards mitral valve in the distant past. She was initially evaluated with a chest and then a CT examination.

The chest radiographs show sternal-wires with a Star-Edwards mitral valve replacement performed for mitral valvular complications (i.e. marked mitral regurgitation) for rheumatic heart disease. There is marked cardiomegaly as well as a mild to moderate degree of central pulmonary venous congestion. The lateral projection shows faint calcification outlining the left atrium. The subsequent CT examination confirms an extensive sheet-like calcification involving the wall of the left atrium. This involves most of the intra-atrial septum as well as portions of the posterior free wall. There is moderate left atrial dilatation. There is no pericardial effusion. The remainder of the pericardium is spared from calcification.

Background
A porcelain atrium (or sometimes termed a coconut left atrium) refers to a situation where all or large parts of the left atrium become calcified. While some consider the two term "porcelain atrium" and "coconut atrium" as being synonymous, other authors differentiate a coconut left atrium from a porcelain left atrium depending on where the inter-atrial septum is involved [1].

The pathology is however similar and it is very often associated with longstanding rheumatic heart disease [2]. While many theories have been suggested, it is largely thought to represent an end result of prior rheumatic pericarditis.

Clinical perspective
Patients often present with longstanding symptoms although some may even be asymptomatic [3]. Most have concurrent atrial fibrillation as well as a past history of mitral valve surgery.

Imaging perspective
Plain digital radiography and echocardiography may show their presence and aid initial detection but might not elaborate on anatomy. In situations where there is pericardial calcification on a frontal radiograph, a lateral radiographic projection can be helpful to appreciate the involvement of the posterior heart wall which comprises of the left atrium.

CT is often considered best at showing an accurate extent of involvement. CT is also useful for excluding other areas of calcification within the pericardium.

Outcome
A porcelain atrium is notable not only for its rarity but also due to its surgical implications [4-7]. In certain cases, an endarterectomy at the time of cardiac valve replacement may be necessary [8].

With regards to our case, the presence of other background co-morbidities and a relative asymptomatic status resulted in the clinical team adopting a more conservative approach to this situation. Involvement of the inter-atrial septum in our case was also also further relative contraindication to a surgical management option [5].

Teaching points
1. Recognising a porcelain left atrium and differentiating from the other related entities giving pericardial calcification is important due to different clinical implications.
2. Recognising the involvement the intra-atrial septum is important to do relative contraindications for further surgery.