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cath_infThe groin is infiltrated with a 1% to 2% lidocaine solution. Most patients require conscious sedation and this varies with the preference of the operator.
The artery is felt by the fingertips, and a needle is directed towards it through a tiny hole, created with the tip of a scalpel. A thin-walled needle is used for this purpose.
When pulsatile blood flow is noted, a curved tip guide wire is then introduced into the needle and guided to the ascending aorta with intermittent use of fluoroscopy.
Cath_shth_insA vascular access sheath is advanced over the guide-wire and placed in the artery. The size of the sheath is dictated by the catheters that will be employed in the case. Thus, a 6 French (F) sheath is used when one anticipates the use of 6F catheters. Remember that 1 mm = 3F. Thus a 6F system has an outer diameter of 6/3 = 2 mm.
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cath_asst Through the sheath, and over a guide-wire, a pre formed (Judkins, Amplatz or other) or multipurpose catheter is inserted and guided towards the ostium of the coronary artery under fluoroscopic guidance. The type of selected catheter is based upon operator preference and may be modified on the basis of the patient's coronary artery anatomy.

The preformed left and right Judkin's catheters are most commomly employed to selectively engage the right and left coronary arteries.

After engaging the ostium of each coronary artery, the cardiologist confirms that the pressure is not damped by a significant ostial narrowing or because the catheter tip is against the wall of the artery. Forceful injection in the latter situation can create a coronary artery dissection when contrast is pushed into the subintimal portion of the artery.

    Under fluoroscopy, 1 - 2 ml of contrast is injected to confim appropriate positioning of the catheter tio. Cineangiographic recordings are then made during the injection of approximately 5 to 9 ml of contrast.

Throughout the procedure, the cardiologist constantly monitors the patient's  pressure and EKG. Angios obtained during injection of the contrast is viewed on a second monitor (to the left of the cardiologist in the picture above).
 Pressures within the aorta and the left ventricle are also measured during the procedure. Blood samples may be drawn to assess their oxygen content, if needed in select cases.

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  The tip of a pigtail (or multipurpose) catheter is advanced retrograde across the aortic valve and placed within the left ventricle. Left ventricular (LV) systolic and end-diastolic pressures (LVEDP) are measured and contrast is injected with the use of a power injector. However,  hand-injection may be occasionally employed in hemodynamically unstable patients or in an attempt to conserve the contrast volume in a patient with renal insufficiency. LV angiography is performed to visualize its size, assess the ejection fraction and look for segmental wall motion abnormalities. The patient is asked to momentarily hold his or her breath during the injection of the contrast to get the diaphragm out of the way. Frequently, the patient experiences a very warm feeling or "hot flash" during the injection. This lasts less than half a minute. Following angiography, LV pressure is remeasured to reassess the response of LV function to the contrast. Pressures are also recorded as the catheter tip is withdrawn from the LV to the aorta. A significant systolic pressure gradient across the LV outflow tract is seen in patients with hypertrophic obstructive cardiomyopathy, and a gradient across the aortic valve is seen in cases of aortic stenosis.

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