Technical notes on chronic fluid-filled catheters and renal artery constrictors for testing hemodynamic drug effects...

Construction and chronic implantation of fluid-filled arterial and ventricular catheters and renal artery constrictors for testing hemodynamic drug effects in conscious dogs are described. The two catheters were made from commercially available silicone rubber and Tygon tubing connected by a molded silicone rubber plate. The blood pressure catheter was inserted via the superficial iliac artery into the abdominal aorta; and the left ventricular catheter, through the apex of the heart. Application of silicone rubber constrictors to both renal arteries resulted in the following hemodynamic values: BPs 180 +/- 4 mm Hg; BPd 111 +/- 2 mm Hg; LVPdp/dt max 3250 +/- 122 mm Hg/sec; and HR 82 +/- 4 beats/sec. Simultaneous recording of LVP and dp/dt signals with Millar Micro-Tip and fluid-filled catheters revealed a difference in signal form and size. Damping the LVP signal of the fluid-filled catheter either with a low-pass filter of 10-30 Hz or using 2-3% dextran solution as catheter fluid abolished this difference. However, a time lag and a difference in dynamic response to positive inotropic agents were still present. Based on our findings, fluid-filled ventricular catheters are recommended for routine work. The effects of antihypertensive, antianginal, and cardiotonic reference compounds could be easily detected with this methodology.