Balloon Tip Catheters
In another study, an 80-cm balloon-tipped 6-Fr catheter (Pressure Products, Model BVCS 6180, San Pedro, CA) (Figure 14 ) was inserted into the right jugular veins of two dogs and advanced to CS. Their left main coronary arteries were also engaged through a 5-Fr AL2 catheter. A small amount of contrast was injected to confirm the CS occlusion after inflation of the balloon followed by its deflation to clear the contrast agent from the CS. Concurrently with contrast injection, the balloon located in CS was inflated and manual blood suction into a heparinized syringe was performed for 30 seconds. Captured contrast was calculated according to grayscale analysis using a polynomial regression curve. Meyer and colleagues suggested due to the presence of small lumen in currently available CS balloon catheters, the flow rate is low leading to enhanced withdrawal times. Thus, increasing the flow capacity of available catheters might be associated with heightened contrast removal efficiency. They also claimed this technique can be applied in any circumstances when a noxious agent should be administered in a selected organ if the draining venous system can be accessed (89).
On the other hand, different catheters are used in humans. Danenberg et al. used a balloon-tipped catheter with two lumens and multiple distal holes (Reverse Berman Angiography Catheter, 7 Fr, Arrow Int, Reading, PA, USA) (Figure 15 ) for accessing the CS. They occluded CS before contrast injection and blood was manually extracted 5-7 seconds post coronary contrast administration and the balloon was deflated for 20-30 seconds after contrast disappearance shown by fluoroscopic images. Extracted contrast concentration was measured by assessing reduction in Hct levels in collected samples compared with simultaneous Hct levels from aorta using the following formula: (1 – Hct in CS extracted blood / Hct in the aorta) * collected blood volume. Although CS was successfully accessed in all seven enrolled patients, the catheter slipped out of the CS led to procedure failure in four participants. However, the entire process was one without difficulties in the remaining three subjects. Another issue was related to fluoroscopy time. The extra time needed for CS cannulation increased the mean fluoroscopy tome in comparison to routine interventions. However, they reported this method can be done in most catheter laboratories with no special equipment. The additional benefit was associated with intermittent CS obstruction. It has been reported that periodic occlusion of CS decreases coronary artery blood flow regardless of the aortic pressure or CS obstruction (95,96) . This reduced flow could be used to decrease contrast volume per injection. Therefore, a reduced amount of used contrast agent and significant contrast extraction can additively decrease CIN risk. They also suggested using superior vena cava to enter the right atrium for CS cannulation as a common technique. However, using femoral access might be quite difficult with standard catheters and they used Simmons II catheter for CS engagement (90).