Here is an interesting case report that appeared in the journal of RSM in January 2014. It was presented by Tom Riddington et al from the James Cook University Hospital, Middlesborough, UK.

Presentation:
A 45 year old farmer presented with a 10 week history of dyspnoea. He had no previous cardiovascular disease and had been normally fit and well.

Clinical Findings:
On clinical exam his BP was 120/65 with a hrt rate of 40BPM. Canon A waves were present at JVP but no audible murmurs were heard. Abdominal exam showed a palpable liver edge with no splenomegaly. Rest of the clinical examination was entirely normal (including the respiratory and nervous systems).

Investigations:
Chest x-ray showed prominent hilar lymphadenopathy. ECG showed complete heart block with complete dissociation of the P waves from the narrow QRS complexes. All blood tests were normal. Echo cardiography was normal. Further biochemistry revealed an elevated serum ACE level but normal calcium levels.

Having noted an abnormal chest x-ray, a thoracic and abdominal CT scan were done. The scan revealed peri-hilar and mediastinal lymphadenopathy with extensive nodularity across the right middle and lower lobes. There was also scattered nodules throughout the lungs. The differential diagnosis was between Sarcoidosis and lymphoma.

The patient was transferred to the cardio thoracic unit where a permanent pacemaker was was implanted. Histology of Lymph node biopsy showed complete replacement of of lymphoid tissue by granulomas with no caseation confirming sarcoidosis.

Discussion.
Sarcoidosis is multi-system granulomatous disorder without caseation in the affected organ. It can affect the lung, skin, eye and CNS. Cardiac involvement is not common and hence diagnosis is missed and only confirmed at autopsy. The authors indicate that clinically detectable manifestations of cardiac sarcoidosis is present only in 5% of patients. Cardiac MRI is becoming an important tool to show areas of scarring and or myocardial oedema.

Cardiac manifestations of sarcoidosis can present bundle branch block, ventricular tachyarrhythmia or congestive hrt failure. If valvular tissue is affected may lead to mitral regurgitation from an incompetent valve. Pericardial involvement is often found at autopsy but pericarditis is never present. Complete hrt block is only seen in about 20 to 30% of patients with myocardial sarcoidosis.

Take Home Point:
When ever you come across a significant AV block in a younger patient, always consider sarcoidosis as a possible cause.