RESUMO
In this paper, a phantom study was performed to evaluate the effect of an epithermal neutron beam irradiation on the cardiac pacemaker function. Severe malfunction occurred in the pacemakers after substantially lower dose from epithermal neutron irradiation than reported in the fast neutron or photon beams at the same dose rate level. In addition the pacemakers got activated, resulting in nuclides with half-lives from 25 min to 115 d. We suggest that BNCT should be administrated only after removal of the pacemaker from the vicinity of the tumor.
Assuntos
Terapia por Captura de Nêutron de Boro , Marca-Passo Artificial , HumanosAssuntos
Agonistas alfa-Adrenérgicos/farmacocinética , Anestesia por Inalação , Anestésicos Inalatórios , Medetomidina/farmacocinética , Éteres Metílicos , Agonistas alfa-Adrenérgicos/metabolismo , Animais , Área Sob a Curva , Biotransformação , Cabras , Meia-Vida , Medetomidina/metabolismo , Sevoflurano , Ovinos , Estereoisomerismo , Distribuição TecidualRESUMO
AIMS: An inherent limitation of single lead VDD pacing is the inability to stimulate the atria. Reprogramming and upgrading the pacemaker system may be required when sinus node dysfunction, atrial undersensing, or atrial fibrillation develop. We evaluated whether routine clinical information is sufficient to select patients to benefit in long-term from VDD pacing. METHODS AND RESULTS: We collected data on 12-lead and monitored electrocardiograms and routine clinical information at implantation of a VDD pacing system in 350 consecutive patients with grade II or III atrioventricular conduction block. The age at implantation was 74.5 +/- 8.0 years, and the follow-up lasted 1.5 +/- 1.5 years. The cumulative maintenance of VDD pacing mode was 91.%. Loss of VDD mode was due to permanent atrial fibrillation in 16 (4.6%), sinus node dysfunction in six (1.7%). atrial undersensing in 11 (3.1%). Chronic atrial fibrillation developed in 23% of patients who had heart enlargement in chest x-ray and a history of paroxysmal atrial fibrillation or flutter. A criterion of normal sinus rate at implantation sufficiently predicted adequate sinus node function. Poor atrial sensing was not predicted by pre-implant characteristics. CONCLUSIONS: According to our data, adequate sinus-driven atrial rate and no history of paroxysmal atrial fibrillation and cardiac enlargement predict maintenance of the VDD pacing mode in elderly patients treated for heart block. Routine information available at implantation is sufficient to guide acceptance of single lead VDD pacing therapy.
