Samarium-153 for intravascular irradiation therapy with liquid-filled balloons to prevent restenosis: acute and long-term results in a hypercholesterolemic rabbit restenosis model

BACKGROUND

It has been shown that irradiation with either beta and gamma sources inhibit neointimal formation. Samarium-153 ((153)Sm) is an isotope with 0.8 MeV, subdivided in three different beta energies and 103 keV of gamma energy. This compound has been tested and used in humans for palliation of pain from bone metastases. The aim of the present study was to evaluate the feasibility and efficacy of brachytherapy with (153)Sm-filled balloon to inhibit neointimal formation in rabbits after balloon overstretch injury.

METHODS

Nineteen rabbits underwent balloon injury in their iliac arteries. In 12 animals (control), oversized balloons filled with saline solution were inflated up to 5 atm for a period of 5 min. In 7 rabbits, the same procedure was performed but using balloons filled with (153)Sm. In all cases, both iliac arteries were treated. The prescribed radiation dose was 15 Gy at 1 mm depth. After 30 days, the animals were sacrificed and their arterial segments were analyzed. Radiation exposure at the animal chest to the table and at a distance of 1 m from the table was measured.

RESULTS

Histopathologic analysis showed a striking reduction in the amount of neointima in the irradiated arteries compared with control vessels (0.36+/-0.21 vs. 1.07+/-0.56 mm(2), P<.01). The dose delivered to the animal chest was 21.5 mR/h, whereas only 1.9 mR/h was measured at the table and virtually no radiation could be detected at a distance of 1 m from the table.

CONCLUSIONS

Brachytherapy with (153)Sm was feasible with minimal personnel exposure radiation and effectively inhibited neointimal formation in this experimental model. These results warrant further experimental and clinical investigations.

[Cardiac amyloidosis. A disease with many faces and different prognosis]

PURPOSE

To identify the principal forms of cardiac amiloydosis presentation in a terciary hospital.

METHODS

Eight cases with cardiac amyloidosis were identified. Five were women, their ages ranged from 23 to 83 years (mean 62). After a medical history and clinical examination the patients were submitted to complementary tests: electrocardiogram (EKG), echocardiogram (ECHO), scintigraphy with technecium pirophosphate and cardiac biopsy these results allowed the identification of their clinical situation.

RESULTS

Seven patients referred dyspnea, 6 were in heart failure, 1 patient had syncope. The EKG identified complete atrioventricular (AV) block in 4 patients, and antero septal inactive area in the other 4. The ECHO showed normal cardiac diameter in all (mean left ventricular diastolic diameter of 46.8) and slight reduction of left ventricular ejection fraction; hypertrophy of the left ventricular septal and posterior walls in all cases, in 7 cases there was a hyper refractile granular sparkling ECHO. Two different groups were identified: one with complete AV block and the second with restrictive cardiomyopathy. The prognosis was different in these two groups. Those with complete AV block evolved better after pacemaker implantation and those with restrictive cardiomyopathy had refractory heart failure and 3 of them died.

CONCLUSION

The increased free wall and septal thickness, the slight systolic dysfunction and the infiltration aspect at ECHO allow us to identify the great majority of the cases. Those patients with restrictive cardiomyopathy evolve with refractory heart failure and most of them die in a few months.

Twenty-four-hour ambulatory electrocardiographic monitoring of surgeons

The objective of the present study was to study the heart rate, presence of arrhythmia, and changes in the ST segment of surgeons with 24-hour ambulatory electrocardiographic monitoring. Eleven surgeons of several specialties were evaluated. All surgeons had one to three operations on the day of the recording. Heart rate, presence of arrhythmia, and changes in the ST segment were determined during the following surgeons' activities: operation, sleeping, car driving, patient appointment, and eating. There was a difference in the mean heart rate among the activities (p = 0.0004). The lowest mean heart rate was registered during sleeping and the highest during operation. Two surgeons had arrhythmias: one had premature ventricular contractions (0.6% of total ventricular contractions) and the other rare premature atrial contractions (0.05% of total atrial contractions) in addition to isolated premature ventricular contractions (< 0.1% of total ventricular contractions). There was no significant difference in frequency of arrhythmia during the activities (p = 0.7150). One patient had periods of inverted T waves. It is concluded that the heart rate of surgeons increases significantly during surgery and that the occurrence of cardiac arrhythmias is not increased in surgeons with no cardiovascular disease during surgery.