Tuesday, 9 February 2010

A Flurry of Endocarditis

Dear Bloggers

There have been two recent cases of infective endocarditis in young adults -- both aged below 30 years with 3rd degree mitral valve prolpase, both growing streptococcal spp from blood cultures and both with previous valvular abnormalities. One had a 'floppy' mitral valve and suspected endocarditis several years before and the most recent patient had confirmed endocarditis in the past.

In the latter case, the patient had a history of preceding tooth extraction prior to the original onset of endocarditis. In this recurrence, the patient had lost the cap to a repaired tooth several months previously. There was no complaint about tooth pain or current problems on direct questioning.

However, on examination, using a simple spatula and a pen light to inspect the teeth, it soon became clear that the base of a previous tooth [the one that lost the cap] was fully exposed and tender to touch. This was the probable site of bacterial entry.

Inspection of the nails revealed two fresh splinter haemorrhages which had occurred since the admission and whilst using antimicrobial agents at the appropriate dose and fully sensitive for the organisms identified.

Bedside fundoscopy examination revealed no abnormalities.

In the former case, there was no evidence of tooth problems. However, in view that the patient also presented with a 'pounding' headache, despite the lack of neurological signs, a mycotic aneurysm needed to be excluded. An MRA indeed revealed an early mycotic aneurysm.

Interestingly, both patients' original chief complaint was fever. Both patients had upper respiratory tract symptoms e.g. rhinorrhoea in the former case and cough with sputum in the latter case. In both instances, the patients were misdiagnosed with conditions such as a 'common cold'. How could this be?

Making a diagnosis of a relatively uncommon infection can be difficult for the uninitiated. More often than not, such symptoms are due to a common cold. Although I do not support such practice, for convenience, it is quick and easy to prescribe 'cold' medications and antibiotics for 'fever' after a cursory look, without appreciating the importance of doing a thorough work up e.g. full history, physical examination and labs, which are time consuming in a hectic outpatient clinic where patients are lucky to get 5 minutes with the doctor. In the season of H1N1 influenza, it is easy to consider everyone has possible flu or a 'common cold'. Hence, without a full workup, endocarditis can be missed and was missed - twice.....

Learning Points and Pearls in Endocarditis

  • Take a thorough history ! That includes previous medical history, medications, allergies, sexual history, travel history etc. If there is any hint of possible valvular disease, ask about dental treatment, rheumatic fever, previous murmurs etc. Don't make assumptions as you may get caught out.
  • Examine the patient with focus on the potential areas that might be affected by what comes to light from the history e.g. cough and sputum = thorough chest examination; fever and previous endocarditis = look for peripheral signs and listen to the heart sounds.
  • Use the modified Duke's Criteria for diagnosis of endocarditis.
  • If there is a suspicion of endocarditis, ask about the patient's dental history. Even if there is no complaint of current problems, nevertheless, inspect the teeth and gums. Do not merely look. Tap them gently with a sterile instrument. A painful tooth / teeth raises the suspicion up a notch. If dentists merely looked at our teeth without touching and prodding them, they might never find the tooth decay!
  • Get into the habit of doing bedside fundoscopic examination. It provides an immediate answer and saves time and money instead of sending the patient to the opthalmologist. The technique requires practice but is invaluable. It is especially important to do if the patient cannot be moved. Patients may not complain of visual loss especially if the peripheral retina is affected so again, we should not make assumptions that there are normal eyes just because the patient has no eye symptoms.
  • Blind prescribing of antibiotics for 'common colds' is not justifiable without a firm assessment and can lead to unwanted side effects and bacterial resistance. Such treatment can result in culture-negative endocarditis thereby making treatment much more difficult to tailor later.
  • Suspected endocarditis patients need 3 sets of blood cultures and an echocardiogram; trans-esophageal if possible. Remember that 'vegetation-negative' endocarditis exists and that trans-esophageal echo is not 100% sensitive. Newer modalities are coming to the fore such as PET-CT for identifying infected valves in 'vegetation-negative' endocarditis. If you are interested in further reading, please see A Bright Spot: Infective Endocarditis and PET/CT. Huyge et al. The American Journal of Medicine, Vol 123, No 1, January 2010
  • A pulsatile headache in a patient with fever and a heart murmur or other peripheral signs suggesting endocarditis, should make one consider a mycotic aneurysm. It is reasonable to undertake further investigations e.g. contrast CT or MRI.
  • Embolisation whilst using appropriate antibiotics is a possible indication for urgent surgery as is a vegetation >10mm. Definite indications for surgery include heart failure (moderate-severe), severe aortic or mitral valve incompetence with evidence of abnormal blood flow, fungal endocarditis or a highly resistant organism and perivalvular infection with abscess or fistula formation. UpToDate support surgical intervention after a second episode of embolisation whilst on antimicrobial agents.
  • Inflammatory markers play very little role of when surgery should be undertaken. Making a decision to operate or not based on the level of CRP is nonsensical as any decision should be based on the degree of haemodynamic instability. Moreover, severe aortic or mitral valve incompetence is usually associated with some heart failure and this condition may further decompensate. Hence, aggressive treatment with early surgery should be considered in such situations. Even in asymptomatic severe valvular incompetence without heart failure, early surgery may show benefit. In a paper by Habib et al on native valve endocarditis and optimal surgical timing, it is stated that 'Patients with severe aortic leaflet destruction and congestive heart failure, patients with perivalvular extension or uncontrolled infection, and patients with high embolic risk have poor outcome under medical therapy. Early surgery is necessary in all such patients with 'complicated' endocarditis unless severe comorbidity is present'. Curr Opin Cardiol. 2007 Mar;22(2):77-83.

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