Balloon dilation of the aorta should be done in – patients showing signs of hypertension, left ventricular hypertrophy, and congestive heart failure.
- Balloons: a selected balloon as outlined in the PULMONARY VALVE BALLOON section.
- Guide wires: Exchange length guide wire of a suitable diameter to the selected balloon.
- Catheters: An end and side hole angiographic catheter 4 or 5 Fr and a NIH MARKER catheter of the same Fr size as the venous sheath.
Prepare the balloon and inflation device as outlined in the PULMONARY VALVE BALLOON section. If a large size balloon is chosen, a 50-ml Luer lock syringe may be needed to inflate the balloon as the usual inflation device will not hold a sufficient volume of fluid. Either way the 50- ml syringe can be used as a negative pressure method for rapid deflation of the balloon.
A diagnostic Catheterisation is done to determine that Coarctation is suitable for ballooning. A 4 or 5 Fr sheath is inserted into the femoral artery. A 20- leader catheter is inserted into the other femoral artery. A venous sheath is inserted into the femoral vein. Right side pressures and saturation are obtained to calculate shunts and cardiac output. If it is right to left communication, LA and LV pressures are obtained. LV and femoral artery gradient are recorded. An LV angiogram is done to demonstrate the Coarctation, and to rule out interruption of the aorta. An NIH marker catheter may be used and when done is positioned in the RA. An end and side hole angiographic catheter are inserted over the wire into the descending aorta. An angiogram is done to outline the Coarctation and to check for a PDA. If there is a patient ductus arteriosus, balloon dilation is contraindicated alone. The catheter is then advanced across the Coarctation. A soft wire, preferably TERUMO hydrophilic –a coated wire may be required. When the wire is in the ascending aorta, the catheter is positioned and a further angiogram may be done to clarify the Coarctation. The diameter of the aorta is measured above and below the lesion using the catheter as a reference and a balloon size is chosen on this basis. Aortic diameter is then measured using a marker catheter. Views showing marker catheter at right angles to the field of views are used for measurement.
Flush the end hole catheter and prepare a sheath of equal or greater size to the shaft of the balloon. Insert the catheter into the hub of the sheath to be used later. This step is not reqd if balloon can go through a reasonable size sheath.
Measure distance between the inside of the 1 cm markers on the X-ray monitor with a ruler. This measurement is – (X)
Measure proximal to the stenosis a segment of the vessel that appears the normal width on/ at a level of the diaphragm. This measurement is – (Y) The known distance of the markers is 1 cm apart.Hence (Y) X 10 mm / (X) = size of stenotic area.
Give Heparin 50/100mls per kg. Position the exchange guide wire across the Coarctation into the ascending aorta. A large curl on the wire before inserting or J tip will assist with keeping the guide wire across the lesion during the exchange procedure. Remove the catheter and the sheath. Holding pressure on the femoral site to maintain hemostasis and prevent the formation of a hematoma. The femoral access site may need to be enlarged using the # 11 scalpel blade. The balloon size may allow for the sheath to remain in-situ so check the manufacturers’ recommends sheath size. Quickly insert the balloon over the wire into the aorta, a slight twisting of the balloon will assist the balloon through the subcutaneous tissue.
Flush the end hole catheter and prepare a sheath of equal or greater size to the shaft of the balloon. Insert the catheter into the hub of the sheath to be used later. This step is not reqd if a balloon can go through a reasonable size sheath.
Position the balloon across the Coarctation. Slowly inflate the balloon until a waist is seen then quickly inflate to the optimal pressure or until the waist disappears. Quickly deflate the balloon. the 50-ml syringe may be needed to increase the negative pressure for a quicker deflation of the balloon. The patient may experience chest pain at this step and it may be 1 or 2 more times until no waist is seen. Allow the patient to recover hemodynamically between inflations. The balloon is then removed; keep the guide wire in place. A twisting action will be needed as the balloon exits from the femoral access site. Apply pressure to maintain hemostasis. Reinsert the catheter and sheath over the wire into the aorta. Advance the catheter into the ascending aorta and remove the wire. Connect to pressure line# 3 and record the gradient from ascending aorta and femoral artery (Line # 1). Repeat the aortogram to outline the Coarctation. If the gradient persists a larger size balloon may be used, repeating the procedure. If the results are satisfactory, withdraw the catheter across the lesion recording the pressure on a pullback. Remove all catheters.
On completion of procedure remove all access lines as required applying sufficient pressure to the insertion site to obtain hemostasis, about 10 minutes. Further doses of heparin may be administered after hemostasis has been achieved. Smaller children and neonates may receive intervenous maintenance fluids for up to 24 hours as this decreases the incidence of femoral artery thrombosis.