Cardiac Catheterization and Angioplasty

Information For Patients Who Have Been Scheduled To Undergo Diagnostic Cardiac Catheterization Or Percutaneous Transluminal Coronary Intervention (Angioplasty)

A clinical decision was made that the performance of a cardiac catheterization is felt to be necessary to provide additional diagnostic information to help make appropriate decisions, which will assist in your cardiac care. The decision to perform cardiac catheterization may be based upon your symptoms, your coronary risk profile, additional suspicious clinical data [i.e. an EKG abnormality], specific non-invasive diagnostic testing, and/or due to additional concern expressed by you, or by a family member with the knowledge that coronary heart disease is generally felt to be a common dangerous, yet treatable condition. A decision to proceed directly to cardiac catheterization (without preliminary diagnostic testing, or even if prior testing was normal) may be both reasonable and prudent, if you have clinical signs or symptoms, which are either suspicious or recurrent.

Specific non-invasive diagnostic testing may have been performed at the request of your primary care physician, or at the discretion of a Suncoast Heart Institute care provider. This testing includes all forms of stress testing (with or without myocardial perfusion imaging) to assess for the presence of arteriosclerotic coronary heart disease. Such testing can include (but may not be limited to) the use of an exercise test (using a treadmill or bicycle ergometer), or a provocative pharmacologic agent (such as Lexiscan (regadenoson), adenosine or dobutamine). These studies are among the most commonly used for this purpose. The use of perfusion imaging markedly improves the diagnostic accuracy of these studies. The sensitivity and specificity of perfusion imaging is roughly 95% and 90% respectively; which suggests that these studies are reasonably accurate for coronary disease diagnosis (but certainly not perfect). We most often use the findings of such a study (along with additional clinical data) to determine which patients may benefit from undergoing diagnostic cardiac catheterization. An abnormality may have been noted on your imaging study that is sufficient enough to recommend a diagnostic cardiac catheterization.

A cardiac catheterization is an invasive diagnostic study, designed to help to evaluate a patient’s cardiac and coronary anatomy. It is done in a specially designed cardiac catheterization suite. For hospitalized patients, the cardiac catheterization (cath) is usually performed urgently or emergently. For outpatients, or if an individual’s clinical findings are less pressing, the cardiac catheterization procedure can be done electively (as an outpatient). If an outpatient cath has been suggested, we request that you contact our office (telephone number is noted above); to have your cardiac cath scheduled (at your earliest convenience).

On the day of your procedure, you should plan to arrive at the hospital at-least an hour ahead of your scheduled procedure time. This will allow ample time to prepare you for the cath procedure. You will receive additional instructions from the hospital staff upon arrival, and will be required to sign additional hospital consent forms. An intravenous line will be inserted, and you will be provided with appropriate sedation for your procedure; you will not be totally asleep however.

When your procedure begins, you will be brought into a cardiac cath suite (which is effectively a modified X-ray suite). The staff will attempt to do all that is possible to see to your comfort. A local anesthetic will be administered to your “groin”, arm, or wrist (depending upon the selected sight for access of the arterial and/or venous vascular system(s). The local anesthetic is given to “numb” the access sight, and avoid discomfort during passage of the catheter(s) through the skin into the blood vessel. There should be no additional discomfort at any time during the study, other than this numbing from the local anesthesia, as there are no sensory nerve- endings present anywhere else that the catheter will traverse. For routine arterial catheterization, a needle will then be passed into the artery that runs close to the surface beneath the numbed skin, to obtain access to the artery.

A sheath will be placed into the artery, which is a hollow tube with a stopper on the end that remains outside the body. The sheath is generally not much larger in diameter than a strand of spaghetti, and will facilitate passage and exchange of the diagnostic catheters used. A catheter (which is nothing more than a long flexible small hollow tube) is passed through the sheath, and positioned with its tip just within the origin of the coronary arteries. The coronary arteries are the tiny vessels which run along the outside of the heart to provide nourishment (oxygen and nutrients) to the heart muscle, and keep it healthy. It is these coronary arteries that tend to accumulate cholesterol plaques that cause blockages; which we refer to as arteriosclerotic coronary heart disease (CAD).

A radiocontrast agent (iodine-containing dye) will be injected through the catheter while a high-speed movie camera is activated through the X-ray machine. As the radiocontrast (dye) to runs-off, down the coronary arteries, it will opacify the vessel lumen, and demonstrate the location any of the blockages that are suspected to be present. The dye injection will be repeated (along with high-speed digital movie imaging) in several positions (different external x-ray camera angles), so that all of an individual’s coronary vessels can be evaluated for the presence of narrowed segments in multiple views. This is called a coronary angiogram.

The procedure may include contrast picture(s) of the ventricular chamber, or “ventriculogram”. A special catheter will be positioned within the ventricular chamber (usually the left ventricle), and a burst of dye (radiocontrast) will be given to assess the left ventricular size, and the wall-motion and systolic performance of the ventricle.

At the beginning or the end of the study, a dye picture may be taken of the femoral artery or other access vessel (where the sheath is inserted). When the vascular access site is the femoral artery (groin), often a vascular closure device (either a collagen plug, a metallic clip, or a suture) will be used to close the artery access site. This allows a patient to be up and around much sooner (usually within an hour or two). The alternative is to allow the access site to seal “naturally”, by applying prolonged manual pressure, and allowing the body’s clotting system to seal the access site sufficiently. The entire time of the diagnostic catheterization should require no more than fifteen to thirty minutes to complete.

If no abnormality is identified (or if it is felt that a patient will not require additional therapy at that time), a patient can should expect to leave the hospital within one-to-two hours after the completion of the procedure. The patient will be regularly assessed by the hospital’s catheterization laboratory staff prior to their departure, to be certain that they had not manifested any reactions to the procedure, the dye or any medications given; and to be certain that the effects of the sedation administered have worn off sufficiently.

If an abnormality is identified which is deemed to be severe enough to compromise blood flow, and is otherwise felt to be “fixable” upon preliminary evaluation in the catheterization laboratory (many blockages can be repaired or corrected at the same time directly through a catheter), the cardiologist may elect (with your permission) to progress to an angioplasty “ad-hoc”.

Angioplasty is the repair procedure of a blood vessel that may ensue in individuals who require it. Angioplasty technically means “vessel modification”. The prototype procedure (developed in 1977) involved the passage of a guidewire through the catheter, down the coronary artery, and across the blockage. The guidewire is not much larger around than a human hair. It has a soft supple tip and a stainless steel shaft. A tiny catheter is passed coaxially over the guidewire to the point of the blockage. The tiny catheter has an inflatable balloon at its tip which can be filled with dye, so the inflated balloon location can be visualized under the x-ray camera. The inflated balloon resembles a hot dog (but is infinitely smaller, no larger than the true diameter of the coronary vessel; generally 1.5 to 4.0 mm in diameter). The balloon stretches open the vessel at the point of the blockage, and may partially compress the atherosclerotic plaque. Once a satisfactory angiographic appearance has been achieved (with a subsequent injection of dye into the vessel), the balloon is then deflated and removed. An improved vessel diameter (with a theoretically improved blood flow down the vessel) will have been achieved.

Many technological modifications and improvements have been made in angioplasty over the past few decades. There now exist a wide variety of specialized catheters for opening vessels and/or plaque removal. These can include laser catheters, shaving or cutting catheters, suction catheters, grinding catheters, specific plaque-modifying catheters, and stents. The interventional cardiologist (physician operator) will select one or more catheters to perform the angioplasty, depending upon the number of vessels involved, the vessel size(s), the number, location, and complexity of the blockages, the appearance of the blockage on the angiogram, and possibly additional details regarding the blockage from measurements obtained using specific diagnostic tools (intravascular ultrasound imaging or Doppler flow wire analysis). There are several factors that can contribute to the selection of a specific angioplasty catheter or device.

A stent is a tiny metallic mesh tube that can be mounted on a coronary balloon, which is deployed into the vessel and left permanently by inflating the balloon to the proper vessel size. There exist “self-expanding” stents which come housed in a thin sheath. Once properly positioned in the vessel, the sheath is withdrawn allowing the stent to expand to its natural size and shape. Stents have the ability to scaffold (prop-open) a vessel, maintaining the vessel’s cylindrical shape, and providing for an improved angiographic appearance. Stent use has reduced the incidence and severity of procedural complications, and has improved the angiographic result immediately and long-term. Because of this, most cardiologists prefer to employ the use a stent as part of an angioplasty procedure (where possible). Newer stents are constructed of combination metal alloys and are coated with special medications (bonded to the metal), which are slowly released into the wall of the vessel over days to weeks. The effects of these medications may last for weeks to months, and are designed to prevent excessive re-growth of the vessel layers (neointimal hyperplasia or fibrointimal hyperplasia), commonly referred to as “restenosis”, which can result in a new blockage at the treated location weeks to months later.

The risks of the diagnostic cardiac catheterization include an extremely low risk of serious complications (stroke, heart attack, and death). These complications occur relatively rarely (usually less than 0.1% of the time). Other minor complications can occur more frequently (but are still rather uncommon), and include; vascular injury at the catheter insertion site [potentially requiring a vascular repair procedure and/or blood product transfusion] (less than 2%), radiocontrast allergy (less than 2%), and kidney damage [related to radiocontrast use] (less than 2%). Elderly patients, patients with known underlying kidney disease, and diabetic patients may be at a somewhat increased risk for kidney problems related to the dye (radiocontrast nephropathy). If you have ever been told that you have a dye (radiocontrast) allergy, or have had kidney problems related to dye administration, or if you feel that you may be at an increased risk of having a dye-related problem from your procedure, you should contact the hospital cardiac catheterization laboratory, and your interventional cardiologist (operator) and inform them of your concerns. Often, additional medications can be administered to help avoid radiocontrast related clinical problems.

If an angioplasty is performed, the procedural risks are greater (which is understandable, as an angioplasty involves a mechanical modification or correction of a coronary plaque that is causing a vessel blockage, and a potential danger in itself). These complications include all of those that are mentioned above for the catheterization procedure. With angioplasty, the incidence of a procedure-related death is less than 1%, and the incidence of a heart attack is approximately 3%. Additional potential risks (with angioplasty) include:

• Coronary vessel dissection (5-10%). This is a separation of the vessel layers.
• Abrupt coronary closure (less than 5%). This is usually related to a coronary dissection and/or a clot (thrombus) with or without plaque debris within the vessel lumen.
• Coronary perforation (1-2%) This can result in bleeding out of the coronary vessel into the adjacent muscle or into the pericardial space (around the heart).
• Hemopericardium with or without cardiac tamponade. Extravasation of blood into the pericardial sac (usually from a coronary perforation) can exert an outward pressure on the heart. This is termed pericardial tamponade or cardiac tamponade. (1%)
• Emergency coronary bypass operation (less than 0.1%)
• Restenosis [development of a recurrent blockage at the treated site] (approximately 30% with routine angioplasty, 15% with the use of a stent, and 1-3% with the use of a “drug-eluting” stent [DES])

In the unusual event that a complication occurs, it may be necessary for your cardiologist to perform additional procedures at his/her discretion to attempt to protect your heart and your life. These procedures may include: insertion of an intra-aortic balloon pump (a mechanical pump to assist with heart function while other medications are provided and mechanical measures are considered or undertaken to provide additional stabilization), insertion of a temporary trans-venous pacemaker (to assist your heart rhythm), and/or performance of a pericardiocentesis (insertion of a needle and possibly also a catheter into the pericardial sac to remove blood or fluid). During such a situation (although uncommon), it may also be necessary for your cardiologist to select additional physicians (anesthesiologist, cardiothoracic surgeon, etc.) to assist with your breathing and subsequent care.

The overall success rate of angioplasty in the hands of an experienced operator is about 95-98%. If an angioplasty is performed, you can usually expect to remain in the hospital overnight and be released the following morning (barring any other complicating issues). Rarely (in an anatomically lower risk procedure completed before the mid-afternoon), you may be allowed to depart the hospital during the same day.