CARDIAC-FUNCTION, METABOLISM AND PERFUSION IN DUCHENNE AND BECKER MUSCULAR-DYSTROPHY

We studied 23 DMD and eight BMD patients using cardiac echo, 24 h ECG and positron emission tomography (PET) with the radiotracers N-13 ammo nia and F-18 fluorine deoxyglucose. The ECG was abnormal in 23 cases w ith alterations in the PR and/or QT intervals, abnormal Q waves in the lateral leads and ST segment depression. Twenty-four hour ECG showed that patients were more likely to produce premature ventricular ectopi c beats with advancing age and 17 patients had paroxysmal ST segment d epression. LV function was normal or mildly reduced in 24 cardiac echo es. PET studies were visibly abnormal in 15 patients. Regional perfusi on defects involving the apex, lateral or anterior left ventricular wa lls were present, nine cases demonstrated a corresponding increase in glucose metabolism. Three out of 15 demonstrated matched perfusion/met abolism defects. One BMD had severe LV dilation with globally poor per fusion and metabolism. The abnormalites seen with PET were confirmed w ith both quantitative and semi-quantitative analysis of radioactive co unts. Similar results were obtained for both DMD and BMD, where both g roups demonstrated significant regional perfusion/metabolism mismatche s. We have shown a reduced uptake of N-13 ammonia which is indicative of a reduction in myocardial perfusion. The use of N-13 ammonia to mea sure perfusion has been validated in animal studies. PET with either N -13 ammonia- or oxygen labelled water can be used to measure myocardia l perfusion. We chose N-13 ammonia as this was most readily available to us.