STEADY-STATE CAPTOPRIL RENOGRAPHY - CONTINUOUS MONITORING OF THE CAPTOPRIL-INDUCED INCREASE IN TC-99M-MAG(3) MEAN PARENCHYMAL TRANSIT-TIME IN RENOVASCULAR HYPERTENSION

Steady-state captopril renography (SSCR) is an original technique for assessing the captopril-induced increase in technetium-99m mercaptoace tyltriglycine ((99)mTc-MAG(3)) mean parenchymal transit time (MPTT) in kidneys affected with functional renal artery stenosis (RAS). The ste ady-state parenchymal activity achieved by constant infusion of (99)mT c-MAG(3) is directly linked to the MPTT of the radiopharmaceutical. Th is steady-state parenchymal activity was continuously monitored from 1 5 min before to 60 min after a single dose of captopril in order to de tect possible disruption of the steady state. SSCR was performed in 11 hypertensive patients with unilateral RAS and in two with RAS of a so litary kidney before renal revascularization (RR). In four of these pa tients, an additional SSCR was performed after RR. Of the ten patients whose hypertension was cured or improved by RR, one presented an unin terpretable SSCR and six presented a positive SSCR on the affected sid e. Control SSCR performed in four of these six patients was bilaterall y negative. SSCR was also bilaterally negative in the three patients w ho showed no blood pressure response to RR. These preliminary results tend to indicate that, in spite of the stability of pre- and post-capt opril hydration and data acquisition conditions allowed by this steady -state technique, the sensitivity is lower than expected. However, the reason for the false-negative results does not seem to be inherent to SSCR.