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Digital gangrene: an unusual cause

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Q1: What are the cutaneous changes in the hand?

The little finger (fig 1; p 118) shows evidence of gangrene with a proper line of demarcation present. Also there is evidence of splinter haemorrhages, Osler’s nodes, Janeway’s lesions, and clubbing.

Q2: What did the blood culture grow and what is the antibiotic of choice?

The blood culture grew Staphylococcus aureus; on further antibiotic sensitivity it showed that the organism was methicillin resistant S aureus (MRSA) positive. S aureus is a common cause of acute bacterial endocarditis, and is known to cause peripheral embolic phenomenon. The antibiotic of choice for MRSA endocarditis is vancomycin 30 mg/kg for a period of four weeks.

Q3: What does the TOE show?

As the initial two dimensional echocardiography did not show any changes we went ahead with TOE; this showed a bicuspid aortic valve with vegetation (fig 2; p 118).

Discussion

Few physicians will be free of the diagnostic challenges posed by endocarditis. Frequently, the presence of endocarditis is disguised, and the prominent organ involvement may vary considerably. Central to the recognition of the disease is the consideration of the diagnosis in any patient who has unexplained fever, who has organ involvement that may be attributed to embolic phenomenon, or who appears to have a multisystem disease.

Digital gangrene in staphylococcal endocarditis is rarely reported, although the incidence of peripheral embolisation is highest with S aureus endocarditis, the frequency of organs and organ systems involved in the embolic phenomenon in the decreasing order are splenic, cerebral, pulmonary, renal, and coronary followed by the extremities.1–3 In a study carried out by Chambers et al in San Francisco General Hospital in patients with S aureus endocarditis it was reported that systemic arterial embolism was seen in 2%–4% of the patients, and the major episodes were of coronary and bony embolic episodes leading to osteomyelitis.4 Digital gangrene was seen in only one patient.

Box 1: Complications of infective endocarditis

  • Heart failure is more common in aortic valve disease (75%) than mitral (50%) and tricuspid (19%).

  • Embolisation is recognised in 12%–40% of patients with subacute bacterial endocarditis and 40%–60% with acute bacterial endocarditis.

  • Conduction abnormalities are detected in 4%–16%.

  • Significant neurological abnormalities are seen in 29%–50%.

  • Mycotic aneurysm develops in 3%–15% of those with infective endocarditis.

  • Renal failure/glomerulonephritis is seen in 5%–10%.

  • Prosthetic valve dysfunction develops in 2%–5%.

Box 2: Cutaneous lesions in infective endocarditis

  • Osler’s nodes.

  • Janeway’s lesions.

  • Subungual splinter haemorrhages.

  • Petechial lesions.

  • Clubbing.

  • Gangrene of extremities.

  • Pustular petechiae.6

  • Purulent purpura.

Perhaps the most striking feature of endocarditis caused by S aureus is the extent of embolic manifestations, especially in left sided disease. Left sided lesions cause the phenomenon more frequently than right sided, indicating that this may be due to microvascular septic emboli.

Aortic valve infection, particularly in association with vegetation and congestive cardiac failure, may be an indication for early surgical intervention. The crucial determinant for surgical intervention remains the severity of heart failure and consequently the valve affected rather than the aetiological agent.

TOE has a substantially higher sensitivity (76%–100%) and specificity (94%) than transthoracic echocardiography (TTE) for perivalvular extension of infection because the TOE transducer in the oesophagus is in physical proximity to the aortic root and the basal septum, where most complications occur.5 The sensitivity of TOE can be improved by imaging in two or more planes, because incremental planes decrease the number of false negative studies and improve the definition of vegetation extent and mobility. One recent published study comparing TTE and TOE in patients with S aureus bacteraemia found TOE was essential to establish the diagnosis of infective endocarditis and to detect associated complications.

Final diagnosis

Digital gangrene in a case of bicuspid aortic valve with Staphylococcus aureus endocarditis.

Acknowledgments

We thank Chetan V, Sunil S, and Amit M for their technical help in preparing the manuscript.

REFERENCES

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