Cardiac Catheterization and Electrophysiology Laboratories
Cardiologists perform diagnostic procedures such as angiograms in a Cardiac Catheterization (Cath) Lab. They also perform a wide range of minimally invasive interventional procedures in this Lab including angioplasty, the placement of Coronary Stents, Implantation of Pacemakers, Distal Protection and the placement of devices to close Septal defects (holes in the heart muscle wall).
A Cath Lab is similar to an operating room, however, diagnostic and treatment procedures performed in this lab usually do not involve large incisions. Instead, most procedures are minimally invasive. This means that they are performed with small incisions or punctures and the use of extremely thin plastic tubes (catheters) to introduce dyes or other substances into the heart which allow blockages to be pinpointed and diagnosed on an electronic screen. The cardiologists use radiologic imaging (x-rays) during the procedure to monitor the movement of catheters and equipment.
Cardiac catheterization is a minimally invasive technique for performing a number of diagnostic tests used in evaluating heart function and blood supply; cardiac valve function; and congenital heart abnormalities.
The procedure involves inserting a long, thin, flexible tube (catheter) into a small incision/puncture in the groin or arm and threading it through an artery or vein into the coronary arteries and/or heart. Dye is then injected and observed as it flows.
This is accomplished using an x-ray machine that produces real-time pictures on a monitor that the physician can watch.
Coronary Angiography or Coronary Arteriography
Coronary angiography or coronary arteriography is a cardiac catheter-based x-ray examination technique by which doctors measure the blood flow and blood pressure in the heart to detect coronary artery obstructions. A special contrast medium or dye, which is visible by x-ray, is injected through the catheter into the chambers of the heart and the arteries supplying blood to the heart muscle (coronary arteries).
The dye helps doctors see how the heart chambers and the coronary arteries are working. The movement of the dye through the heart and coronary arteries is viewable on a monitor and recorded as an angiogram. The dye used for the test is harmless and is naturally passed from the body during urination.
Percutaneous transluminal coronary angioplasty (PCTA)
Also known as angioplasty, this is a non-surgical, cardiac catheterization technique for re-opening diseased coronary arteries. Typically, it is performed using a miniature balloon that is positioned in the narrowed area of the coronary artery then inflated for a few seconds, compressing the plaque and dilating (widening) the narrowed artery. When the balloon is deflated and removed, the blood can flow more easily. This is called coronary artery balloon dilation or balloon angioplasty.
How Is Balloon Angioplasty Performed?
Patients are usually awake, but sedated, during angioplasty. An appropriate access to the arterial system is located – usually in the patient’s groin. The area is cleaned with an antibiotic soap and the area is numbed with a local anesthetic. The physician inserts an ultra-thin, flexible tube (catheter) through a very small incision (or puncture) into the artery and, guided by x-rays that are viewable on a screen, threads it through the arterial system until it reaches the clogged coronary artery.
Next, an ultra-thin wire is inserted through the catheter and threaded across the blockage. Over this wire, but still inside the catheter, a thin, tiny, expandable balloon is passed to the blockage. The balloon is then inflated. It pushes and compresses plaque to the side and stretches the coronary artery somewhat. This may be done more than once. The balloon is then deflated a final time and the catheter, balloon and wire are removed. As a result, the coronary artery is more open and blood can flow more freely. Angioplasty can last from 30 minutes to a few hours, depending on the type of blockage and how many there are.
Placement of Stents: Coronary Angioplasty with Stenting
In order to prevent the plaque from closing the artery again, after an angioplasty, a coronary stent may be used during the procedure. The stent is a tiny metal (usually titanium) mesh tube that fits over the balloon so when the balloon is inflated, the stent expands against the artery walls, becomes imbedded and, when the balloon is deflated and removed, remains in the vessel – acting like a scaffold to help keep it open.
In approximately 20 percent to 25 percent of stent procedures, scar tissue may develop around the area of the stent causing restenosis (re-blockage) within six months of treatment. As a preventive measure, a special drug-eluting (drug-coated) stent may be used during angioplasty. The drug is released over time and inhibits the development of scar tissue around the area reducing the risk of restenosis to less than 10%
Some concerns have been raised recently regarding possible risks associated with drug-eluting stents. The medical community consensus is that risks are minimized if drug-eluting-stent recipients take prescription platelet inhibitor medication (e.g., Plavix or Ticlid) for six months following the placement of the stent. Patients who receive a bare-metal stent will generally only take a platelet inhibitor for six to eight weeks.
Distal Protection Devices
During certain angioplasty procedures, blood clots and fatty deposits in the arteries can be dislodged and clog the vessel further downstream. This debris can cause serious problems – namely, a heart attack. Distal protection devices employed during these procedures use a specialized guidewire and catheter to collect and remove this “debris.”
Distal protection substantially minimizes the risk of floating debris that can break off during angioplasty. The distal protection device – a miniature net-like mechanism – is affixed to the tip of the catheter that the physician performing the angioplasty threads past the site of the blockage. It is opened to trap any floating debris that may be dislodged during the balloon expansion and stenting processes. The net is then closed with the debris inside it and removed.
Primary Angioplasty for Heart Attacks
Patients experiencing heart attacks need to be treated ASAP after the onset of symptoms to achieve the best outcomes. Research has shown that primary angioplasty is more effective than thrombolytic therapy (use of clot dissolving drugs) in preserving life after a heart attack. Unfortunately, fewer than 20% of U.S. hospitals have facilities to perform PTCA. Consequently, it is important to know which hospital offers primary angioplasty and when it is available. University Hospital has staff available 24 hours/day every day of the year to provide this life-saving therapy.
Acknowledging that “Time is Muscle,” Emergency Medical Services and the Department of Cardiology at University Hospital have implemented a new program designed to ensure the quickest possible response time. According to this plan, when responding to a suspected cardiac patient, EMS staff will immediately electronically transmit the patient’s 12-lead EKG from the home, office, shopping mall or other location where the heart attack occurred along with the patient’s diagnostic information. The transmitted EKG is received on a hand-held device carried by several members of the Cardiology medical staff. The cardiologist will then review the EKG and the patient’s clinical information, decide on a plan of care and relay it back to the EMS personnel while the patient is still enroute. This way, the EMS personnel receive a diagnosis and direction from a cardiologist well before arrival at the hospital where medical staff are then ready to proceed with the appropriate treatment including medications and Cath Lab procedures.
Cardiovascular (CV) Defect Repair
Some congenital cardiovascular defects let blood flow between the heart’s right and left-sided chambers. This happens when a baby is born with an opening in the wall (septum) that separates the right and left sides of the heart. This defect is sometimes called “a hole in the heart.” The two most common types of this defect are atrial septal defect (ASD) – an opening between the heart’s two upper chambers – and ventricular septal defect (VSD) – an opening between the heart’s two lower chambers.
ASD (Atrial Septal Defect)
In an ASD, the opening between the heart’s two upper chambers lets some blood from the left atrium (blood that’s already been to the lungs) return via the hole to the right atrium instead of flowing into the left ventricle, out the aorta and to the body. If it is of significant size, closing the atrial defect in childhood can prevent serious problems later in life.
Until recently, the only way of repairing an atrial septal defect (ASD) involved open-heart surgery. It now has become possible to close ASDs during cardiac catheterization with an Amplatzer® Occluder. The fabric used in the device is similar to that used by surgeons to repair some heart defects. The wire discs are made of a biocompatible alloy (Nitinol), which has been employed in different kinds of surgical ‘implants’ over many years.
The Amplatzer device, Food and Drug Administration-approved for use in December 2001, is inserted through a catheter and covers the ASD by attaching to the atrial septum. Traditional surgical closure of atrial septal defects has proved complication-free in more than 99 percent of cases. Although the Amplatzer device has been in use for a short time its success rate appears to be high.
The device can also treat patent foramen ovale (PFO). The foramen ovale is an opening between the right and left atria of the fetal heart that is supposed to close after birth. If it remains open, this is called a patent foramen ovale. In most cases PFO is clinically insignificant. However, it may be associated with paradoxical embolus, a condition in which a clot originating in the venous circulation gains access to the arterial circulation through the PFO, resulting in a transient ischemic attack (TIA) or stroke. The use of the Amplatzer device can close this opening thereby eliminating the risk.
Using a special catheter, samples of heart muscle can be safely removed for microscopic analysis. In certain heart muscle disorders, endomyocardial biopsy can aid in determining therapy. Biopsies are also used to monitor immune rejection in patients who have undergone heart transplantation.
Cardiac tamponade is a t condition in which a large amount of a liquid accumulates in the (the protective sack around the heart) in a relatively short time. The created pressure prevents proper filling of cavities. Tamponade can happen acutely, such as from a stab wound, from surgery, or from the heart muscle rupturing as in some rare heart attacks. Chronic Cardiac tamponade is a slower process, where up to two of fluid can enter the pericardial space over a period of time, the pericardium stretching to accommodate. Pericardiocentesis is the preferred method for safe and effective removal of fluid around the heart (pericardial effusions).Under x-ray guidance, a needle is inserted into the pericardial space and the fluid is removed. This relieves the pressure and allows the heart to function normally.