RESUMEN
BACKGROUND: Percutaneous transendomyocardial injection with an injection catheter is a new drug delivery method for e.g. therapeutic angiogenesis. Little is known about the efficacy of this drug delivery technique. We studied efficiency and retention of transendomyocardial injections with a NOGA guided injection catheter system by using scintigraphy with radio-labeled model drugs. METHODS: Ten non-ischemic landrace pigs were used. In each animal 2-3 transendomyocardial injections were performed using a 3-D mapping based catheter system called NOGA. As a model for proteins like angiogenic growth factors we used (99m)Tc labeled albumin and as a model for small particles like microspheres or adenovirus we used (99m)Tc labeled colloid albumin. Efficiency of the injections and retention of the transendomyocardial deposited substance were evaluated by a gamma camera during and after injection of 0.1 or 0.2 ml. RESULTS: All 29 injections showed scintigraphic proof of intramyocardial deposition. The average injection efficiency of all 29 injections was 26 +/- 23%. The average injection efficiency of 0.1 and 0.2 ml injections were 33 +/- 30% (n = 8) and 24 +/- 20% (n = 21), respectively (p = 0.33). Intramyocardial retention curves of albumin showed a rapid wash-out within the first 2 hours of the injection, whereas the retention of colloid albumin showed no decrease. In conclusion, transendomyocardial delivery of proteins or particles with an injection catheter show favorable efficiency rates, however the retention time of intramyocardial deposited small proteins like albumin is short. This may indicate the need for sustained release systems of angiogenic growth factors for intramyocardal injection in therapeutic angiogenesis.