Case study of radiation therapy treatment of a patient with a cardiac ventricular assist device.

A patient with a cardiac ventricular assist device (VAD) with computer-controlled driver presented to our department for radiation therapy. The treatment plan was 4500 cGy to the rectum over 25 fractions with 15MV photon beams. All beams avoided the pump and leads. The response to electromagnetic interference (EMI) was evaluated by observing a duplicate driver in the treatment configuration as the patient's fields were delivered to a solid water equivalent phantom. Pretreatment dose assessment included calculations with Pinnacle treatment planning system, AAPM TG36 data analysis, and MOSFET measurements on the surface of the driver during the phantom irradiation. During the first patient treatment, MOSFETs were placed on the pump and leads, approximately 1cm from the left lateral treatment portal. No additional shielding was applied to the VAD. EMI was absent and the VAD operated normally during the pretreatment test and throughout the treatment course. Radiation to the driver was too low to be detected by the MOSFETS. Cumulative dose estimates to the pump were 425 cGy to 0.1cc (DVH), 368 cGy (TG36), and 158.5 cGy (MOSFET). MOSFET readings to the leads were 70.5 cGy. External beam radiation treatment was safely delivered to a VAD dependent patient. The VAD exhibited no adverse response to EMI and doses up to 425 cGy. Our results are based on one case and further study is encouraged.

Effect of the TNF-alpha-promoter polymorphism on cardiac allograft rejection.

BACKGROUND: A polymorphism exists in the tumor necrosis factor alpha (TNF-alpha) promoter (position -308, G/A = TNFA1/TNFA2). The TNFA2 allele is associated with increased TNF-alpha production in vitro and has been reported to increase the risk of allograft rejection in pediatric recipients of cardiac transplantation. We examined the effect of the TNFA2 allele on the risk of allograft rejection in adult cardiac transplant recipients. METHODS: We prospectively analyzed 57 subjects (aged 54 +/- 11 years, 84% men, 49% ischemic) who underwent cardiac transplantation between October 1996 and July 2001. Patients were observed after transplantation (mean, 910 +/- 605 days) and the frequency of allograft rejection (biopsy Grade > or =2) in patients with the TNFA2 allele (Group A, n = 15) was compared with TNFA1 homozygotes (Group B, n = 42). Overall survival and time to rejection episodes also were compared between groups. RESULTS: The frequency of allograft rejection was similar between groups (Group A, 8/15 [56%]; Group B, 22/42 [52%]; p = 0.77). Time to rejection also was comparable (Group A, 17 +/- 11 days; Group B, 20 +/- 20 days, p = 0.74). Overall post-transplant survival was similar between groups (1- and 2-year percentage survival: Group A, 87% and 78%, Group B, 88% and 82%, p = 0.35). CONCLUSION: The TNFA2 allele was not associated with increased risk of rejection in adult cardiac transplant recipients. The impact of this polymorphism on overall post-transplant outcomes will require investigation in larger multicenter studies.