Bacterial endocarditis : Mitral valve

Images Nick Stewart, text  Genevieve Carbonatto

A 50 year old man presents to the ED with a 6 week history of general malaise, fevers, night sweats and weight loss (10 kg). He had been prescribed 7 courses of Augmentin by his GP and felt generally better on this antibiotic. An outpatient CT showed some nodes around the pancreas and he is referred to the Emergency department for investigation of malignancy. A CT is repeated in the Emergency department. There was no evidence of malignancy but there is  a small pericardial effusion with splenic infarcts.

In the Emergency department he lookes pale and unwell. BP 130/70, HR, 120/min, loud pansystolic apical murmur. Hb 93, CRP 130, ESR 80.

A point of care ECHO is performed looking for endocarditis

PLAX

Both the PMV and the AMV leaflets appear to be thickened with a definite mass visible at the tip of the AMV leaflet. There is also a small pericardial effusion. The LA is dilated. The LA in this view should be similar in size to the ascending aorta  and the RV. This is called the “rule of thirds”.

There is mitral regurgitation from at least 3 points.

4CV

There is severe dilatation of the  LA and moderate dilatation of the RA. The  pericardial effusion is associated with RA wall collapse. The AMV leaflet mass is visible as is the thickening of the tip of the PMV leaflet.

Colour Doppler shows severe mitral regurgitation. The regurgitation is taking up the whole of the LA. Again there are several points of regurgitation

Subcostal view

The pericardial effusion associated with RA collapse is visible.

The patient is admitted for IV antibiotic and a MV replacement.  He grew streptococcus mutans from his blood cultures. He had no known  risk factors for bacterial endocarditis.

Discussion

The complications of native valve endocarditis are

  • Embolism: This is the primary manifestation of endocarditis in 28 – 47% of all patients. The risk of embolisation depends on the vegetation size (>10 mm) and it’s mobility. The risk is higher before antibiotics are started, if the AV or MV are involved, if the vegetation is pedunculated or if the organism is staphlococcus aureus. Mortality is high with embolisation
  • Valve destruction: leaflet tears, leaflet perforations, prolapse, annular destruction and destruction of subvalvular apparatus
  • Regurgitation which may cause heart failure: This is common and found in 30% of patients. The speed of developing failure depends on how quickly perforation occurs. Severe regurgitation leads to haemodynamic instability, volume overload and pulmonary oedema
  • Pseudoaneurysms
  • Abscess formation which may cause fistulas 
  • Mycotic aneurysms

Endocarditis may be difficult to see on transthoracic ECHO because the lesions are not always pedunculated. They can be broad based and sessile, presenting as a thickening of the valve leaflet, lobulated or even flat. TOE is a much better way to assess for bacterial endocarditis.

Reference:

  1. 1,2,3 sonography

 

 

 

 

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