The following electronic only articles are published in conjunction with this issue of Heart.

Gentamicin induced ototoxicity during treatment of enterococcal endocarditis: resolution with substitution by netilmicin

J E East, J E Foweraker, F D Murgatroyd

Enterococcal endocarditis can be very difficult to eradicate, requiring prolonged treatment with a combination of a penicillin and an aminoglycoside. In this patient with a pacemaker associated enterococcal endocarditis, ototoxicity occurred due to total gentamicin dose despite plasma concentrations consistently within the treatment range. Substitution with netilmicin, without a break in aminoglycoside treatment, resulted in a rapid improvement in hearing and allowed the required course of aminoglycoside to be completed. The risk factors for ototoxicity with gentamicin are reviewed, in particular the dangers of increasing age and of multiple and prolonged courses. Close treatment monitoring does not totally avoid this risk, especially when prolonged aminoglycoside treatment is required. This case emphasises the need for prompt investigation and adequate, definitive treatment of enterococcal endocarditis to avoid the increased risk consequent on repeated courses of antibiotics. The resolution of the ototoxicity with netilmicin is consistent with other reports of lower cochleotoxicity than with other aminoglycosides.

(Heart 2005;91:e32) www.heartjnl.com/cgi/content/full/91/5/e32

Lysyl oxidase deficiency: a new cause of human arterial dissection

I Sibon, P Sommer, J M Daniel Lamaziere, J Bonnet

Spontaneous coronary artery dissection is a rare cause of myocardial ischaemia. The underlying mechanism is unknown but some dissections are associated with extracellular matrix disorganisation of genetic origin. A deficiency in extracellular matrix protein cross links has rarely been studied. A single clinical case of spontaneous coronary artery dissection is reported. Lysyl oxidase (LOX) and extracellular matrix organisation were investigated by skin immunohistology and polymerase chain reaction of LOX expression. Both approaches found a dramatic LOX decrease. LOX deficiency has a major role in human arterial wall organisation during development. The suspected mechanism is an elastin or collagen polymer cross linking deficiency.

(Heart 2005;91:e33) www.heartjnl.com/cgi/content/full/91/5/e33