Supervision of thrombolysis of acute myocardial infarction using telemedicine.

The treatment of acute myocardial infarction (MI) constitutes a significant problem in remote geographical areas of Greece. Furthermore, thrombolysis, the treatment of choice in the early phase of acute MI, requires the supervision of an expert. We have used thrombolytic treatment, using telemedicine, in remote medical centres. The Onassis Cardiac Surgery Centre was linked to six remote Aegean islands via telemedicine systems which permitted the transmission of 12-lead electrocardiograms (ECGs). The thrombolytic agent anistreplase was administered to patients with acute MI. Supervision, including consultation for treatment of complications, was achieved using the telemedicine system. One hundred and fifty-two ECGs were transmitted during 24 months, of which 108 (71%) indicated specific treatment of a cardiac condition. Ten cases were diagnosed as having acute MI and eight of these were treated with anistreplase. All patients survived acute MI and complications were treated locally. The application of thrombolytic treatment in acute MI is feasible in remote areas, with the use of a telemedicine system.

T2 relaxation time study of iron overload in b-thalassemia.

Myocardial iron deposition occurs as a result of blood transfusion therapy in b-thalassemia major patients. Since this deposition causes various cardiac complications, it is of interest to assess the iron content of the myocardium in relation to the clinical picture of the patients. Two different MRI indices were used to achieve this purpose: the T2 relaxation time and the heart/skeletal muscle signal intensity ratio. ECG gated spin echo images were obtained from 54 adult thalassemic patients, with a mean age of 26 (18-44) years, at TE = 22 ms and 60 ms, using a 1.5 T system. Patients were divided into 2 groups (A and B), according to their serum ferritin levels (> or < 2000 ng ml(-1)). Results were compared with nine controls, with a mean age of 25 (18-43) years. Heart T2 relaxation time in controls (44.3 +/- 3.5 ms) was higher than in group A (29.9 +/- 5.7 ms, P < 0.001) and group B (33.4 +/- 6.8 ms, P < 0.01). T2 was measurable in 66% of group A and 83% of group B patients. The heart/muscle signal intensity ratio in group A (0.45 +/- 0.27) was lower than in group B (0.82 +/- 0.33, P < 0.001) and the controls (1.15 +/- 0.20, P < 0.001). The heart/muscle signal intensity ratio was measurable in 94% of the patients and demonstrated an inverse relationship with the serum ferritin levels (r = -0.52, P < 0.01). This study indicates that the heart/muscle ratio is a sensitive index of iron overload and it can be measured in the majority of patients, irrespective of tissue iron concentration, thereby offering an advantage over the use of T2 relaxation time.

Myocardial iron deposition in beta-thalassemia studied by magnetic resonance imaging.

Myocardial iron deposition is a common finding in beta-thalassemia. The iron content of the myocardium was assessed using the T2 relaxation time of the heart. The T2 relaxation time of the liver and skeletal muscle was also assessed in order to study the relation of iron deposition between heart, liver and skeletal muscle. ECG gated spin echo images were obtained from thirty-eight consecutive adult thalassemic patients examined in an outpatient clinic, aged (x +/- SD) 25 +/- 6 years, using a 0.5 T system. Patients were divided into groups A and B, according to their average serum ferritin levels of the preceding five years (> or < 2000 ng/ml). Results were compared with nine controls, aged 24 +/- 7 years. Heart T2 relaxation time in the control group (x +/- SD) (48.3 +/- 5.5 msec) was higher compared to group A (28.4 +/- 6.7 msec, p < 0.001) but not to group B (43.4 +/- 7.4 msec). The T2 relaxation time of the heart correlated positively with the T2 relaxation time of the liver (r = 0.68, p < 0.001) and negatively with ferritin levels (r = -0.67, p < 0.001). There was no correlation with the T2 relaxation time of skeletal muscle. This study indicates that regularly transfused beta-thalassemia patients may present with a broad variation of heart iron deposition which, however, is related to serum ferritin levels.

Adenosine combined with dynamic exercise for myocardial perfusion imaging.

OBJECTIVES: This study investigated whether combining exercise with adenosine would reduce the adverse effects of adenosine vasodilation. BACKGROUND: Adenosine vasodilation is effective for perfusion imaging but causes frequent unpleasant noncardiac adverse effects, high noncardiac tracer uptake and occasional arrhythmias. METHODS: Of 500 consecutive patients referred for thallium-201 myocardial perfusion imaging, 407 were randomized to three study groups: 6 min of adenosine infusion alone; 6 min of adenosine with submaximal exercise; or symptom-limited exercise with continuous adenosine. Minimal detectable differences are presented; a significance level of 0.05 with a power of 80% is assumed. RESULTS: There was no difference among the three groups in sensitivity and specificity (overall 96% and 78%, minimal detectable differences 5.5% and 11%, respectively) for detection of coronary artery disease or stenosis in individual coronary arteries. There was a trend toward improved sensitivity in the combined exercise groups compared with that in the adenosine-only group (98% vs. 93%, p = 0.07, minimal detectable difference 6%). Noncardiac side effects were reduced by 43% in the exercise groups (p < 0.0001), and major arrhythmias were reduced by 90% (p < 0.0001). There was no effect on minor arrhythmias (25% vs. 22%, p = 0.6, minimal detectable difference 12%). The heart/background ratios were higher in the exercise groups (all p < 0.02). Each ratio was correlated with the exercise level achieved (all p < 0.001). The reversibility score increased with exercise (p = 0.04), as did the number of patients and segments with reversible defects (both p = 0.03). CONCLUSIONS: Combining exercise with adenosine infusion reduced the noncardiac side effects of vasodilation and major arrhythmias while improving redistribution and heart/background ratios. These findings may be clinically important. Although maximal exercise with adenosine infusion produced optimal results, the improvement over the submaximal exercise protocol was minor, and this has the advantage of being simple and achievable within the normal 6-min duration of the adenosine infusion.