Case Study - Cardiac symptoms of unusual origin

A rare cause of heart problems in a teenager posed an initial diagnostic problem for Dr Keith Barnard.

John, aged 18, was about to embark on a gap year trip to the Antipodes via the Far East, and he had been to see me to ask for advice about medical problems he might encounter in under-developed countries.

He came back a few weeks later with symptoms that would compromise his travels.

He was a fit young man who played tennis, so it was a surprise that he presented with shortness of breath and feeling faint for the preceding 10 days.

The previous night he had been at a party, where he had to stop dancing because of palpitations and breathlessness, and said he 'passed out' for a minute or so.

'I know what you are thinking, doctor,' he said. 'But I wasn't drunk - three cans of lager, that's all, and no drugs. I promise, I don't even smoke.'

On examination his temperature was normal, as was his BP, but his heart rate seemed rather variable, perhaps more than I would expect with a sinus arrhythmia, but with no murmurs. His lungs were clear and a neurological assessment was also normal. There were no abnormalities in the urine.

We went back over his history, and he could not think of anything else that might be relevant, although he had had a rash on his legs about three weeks ago. John showed me some fading reddish macular patches on his thighs.

'I feel tired, too,' he added, 'I'm normally full of energy. Last month I went camping in the New Forest with my friends, and I was fine.'

I asked him if he received any bites. 'We did get bitten, mosquitoes and things mostly,' he said, but he seemed unconcerned.

An abnormal ECG
Because of his history of palpitations, I arranged for an ECG to be done in the treatment room, and I did not like the look of it. The P waves were all over the place and did not correspond to the ventricular contractions in any discernable pattern.

I had to check in my ECG atlas to confirm that what I was seeing was atrio-ventricular dissociation, indicating a disorder of the conduction system. This prompted a conversation with our local cardiology department, who saw John immediately and admitted him to hospital.

I suspected that this young man possibly had Lyme disease, with his history of being bitten while camping and subsequent rash. What I did not recall was that cardiac complications of Lyme disease may occur in the early phase of the illness in up to 8 per cent of patients, and usually about 21 days after the onset of the rash of erythema migrans.

Cardiac manifestations include atrio-ventricular block, myopericarditis, intraventricular conduction disturbances, bundle branch block and congestive heart failure. Temporary cardiac pacing may be required in up to a third of cases, but the good news is that complete recovery occurs in more than 90 per cent of patients.1

John was treated with doxycycline (cefuroxime and amoxicillin are also commonly used) and his conduction disturbance slowly resolved. He had to postpone his gap year adventures, but still managed to go to Australia for six months.

Lyme disease
This tick-borne illness is caused by a spirochete, Borrelia burgdorferi, and is prevalent in several areas of the UK, including the New Forest, the Lake District and the Scottish Highlands. According to the Health Protection Agency there are no more than 2,000 cases of Lyme disease in the UK each year.

Many people do not realise they have been bitten. If the tick is found soon after biting, infection is unlikely, because the tick probably has to be attached for more than 24 hours to transmit the infection.

Presentation may be with a red rash that looks rather like a bull's-eye, with a dark red centre surrounded by a paler area with an outer concentric red ring. This may be accompanied by fever, muscle and joint pains, and sometimes neurological symptoms.

However, many patients do not have troublesome acute symptoms in the early stages. The outlook is generally good, especially if diagnosed in the early stages.

  • Dr Barnard is a former GP in Fareham, Hampshire

Reference

1. Nagi KS, Joshi R, Thakur RK. Cardiac manifestations of Lyme disease: a review. Can J Cardiol 1996; 12: 503-6.

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