Experiencia de 36 años con marcapasos implantables: un análisis histórico / A 36 year experience with implantable pacemakers

Background: The implantation of pacemakers improves cardiac function and quality of life, in particular with dual chamber DDD and DDDR modes. Aim: To evaluate our clinical experience and results on pacemaker implantation, from 1963 to 1998. Material and methods: Computerized data collected from 2,445 consecutive paced patients was reviewed. A total of 3,554 operative procedures were performed, including 412 procedures for complications and 697 pacemaker replacement. Patient survival was determined from clinical records, inquiry to pacemaker manufacturers and death certificates from Servicio de Registro Civil e Identificaci-n de Chile (Chilean Civil and Identification Registry). Results: Use of dual chamber (DDD and DDDR) pacemakers increased progressively up to 74 percent from 1988 to 1998. Complication rate was 42 percent in the 1963-1976 study period, it decreased to 10.6 percent in the 1977-1987 study period, and to 5.6 percent by 1988-1998. Only two patients died during surgery in the study period (0.08 percent). In the 1977-1987 period, pacemakers lasted 10.6 years. Survival rates were 52 percent at ten years, 33 percent at 15 years, and 21 percent at 20 years, with a median survival of 11.7 years, and 7.24 years in patients over 80 years old. Conclusions: Transvenous permanent pacing can be accomplished today with a low complication rate, mainly due to better technology and surgical procedures

La importancia de la reprogramación en la vida útil y costo de implante de los marcapasos bicamerales / The importance of adjusting parameters for the duration and cost of dual chamber pacemakers

Antecedentes: realizamos un estudio prospectivo de 236 pacientes sometidos a implante de marcapaso DDD bicameral. Los parámetros nominales de implante permiten márgenes de seguridad de estimulación más que suficientes. Las mejoras en la tecnología de marcapasos y electrodos han permitido reducir los umbrales de captura y, por lo tanto, la programación de los parámetros de salida. Dichos cambios pueden significar una reducción en el consumo de la batería a largo plazo, produciendo una mayor durabilidad del generador. Métodos y resultados: se estudió 236 pacientes consecutivos implantados con marcapasos Pacesetter DDD para determinar el impacto de la reprogramación en la durabilidad y costo del implante del marcapaso. Se excluyó a 36 pacientes, 19 murieron, 13 no tuvieron suficientes controles y 4 fueron reprogramados a modo VVI. Los 200 pacientes restantes completaron al menos 18 meses de seguimiento y se les implantó generadores capaces de medir umbrales de estimulación crónico, ancho de pulso, impedancia y energía de la batería. Comparamos la durabilidad estimada basada en la energía de la batería bajo parámetros de implante nominales, con aquella basada en los parámetros obtenidos tras la reprogramación durante el seguimiento. La estimación de durabilidad fue de 6,89 años bajo parámetros nominales y de 10,5 años bajo parámetros de programación final (p<0,001). Conclusiones: la reprogramación podría aumentar la durabilidad y reducir el costo de implante de los marcapasos. En nuestro estudio la reprogramación aumentó la durabilidad del marcapaso en 3,6 años y ocasionó una reducción promedio en sus costos de 330 dólares por año

Marcapasos bicamerales: resultados inmediatos y alejados / Short and long terms results of dual chamber pacemaker use

Background: Continuous improvement of dual chamber DDD pacemakers, electrode stability and programmed sequential stimulation changed the prognosis of patients implanted with these devices. Aim: To report our experience with the use of dual chamber pacemakers. Material and methods: One hundred seventy six patients (116 male), aged 13 to 91 years old, who received a dual chamber pacemaker implant, are reported. Patients were followed for a mean of 2.6 years. Results: Indications for DDD pacemaker were complete atrioventricular block in 43 percent, sick sinus syndrome in 32 percent, paroxysmal A-V block in 24 percent. All pacemakers were Siemens-Pacesetter and were provided with an automatic sensing and threshold device. J shaped atrium electrodes were used in 78 percent of patients and screw-in electrodes in 22 percent. Post operative complications were displacement of atrial electrode in 8 patients, of ventricular electrode in 6 patients, infection in two patients and a hematoma in one. Chronic parameters, measured after six months, were within expected ranges and allowed a good reprogramming of pacemakers. Long term programming aimed to reduce battery depletion, enhance device performance and improve hemodynamic conditions. Normal sequential stimulation was achieved in 154 patients (87 percent), 14 (85) patients died of cardiovascular disease not related to pacemaker function. Eight patients were in atrial fibrillation and were reprogrammed to VVI and DDI modes. Conclusions: DDD pacemakers are reliable and afford symptomatic relief in a broad spectrum of patients

Efectos cardiovasculares del acortamiento del intervalo AV mediante estimulación eléctrica del corazón en miocardiopatía dilatada / Cardiovascular effects of AV interval shortening with heart electric stimulation in dilated cardiomyopathy

Patients and methods: Nine patients with dilated cardiomyopathy were studied. Hemodynamic and tissular perfusion values, echocardiographic and radioisotopic ventricular function parameters were measured before and after six hours of AV interval shortening with electrical stimulation of the heart. Results: After electrical stimulation, cardiac output increased from 3.38 ñ 0.8 to 32.87 ñ 0.79 l/min (p < 0.05). Pulmonary capillary pressure decreased from 23.8 ñ 8.9 to 19.8 ñ 9.2 mm Hg (p = NS). There were no significant changes in ventricular function parameters or in systemic and pulmonary pressures. Conclusions: Electrical shortening of AV interval in patients with dilated cardiomyopathy increases cardiac output but does not change ventricular function parameters