Cardiac lab technology helps save patients’ lives

Imagine a tiny, delicate instrument inserted into the bloodstream and then guided slowly into a coronary artery. By using this tiny device, a surgeon can perform a medical procedure that saves a patient’s life — without ever opening up the patient’s chest.

Sound like science fiction, something that Doctor McCoy might perform in a “Star Trek” episode? Well, neither the instrument nor the medical procedures are fiction; the future has arrived today at the Peter F. Yacavone Cardiac Laboratory, part of the Heart Center at the Eastern Maine Medical Center. The facility is also known as the cardiac-catheterization lab.

According to Deborah Johnson, RN, who is the Heart Center administrator, several diagnostic and therapeutic procedures are available at the laboratory.

Cardiac specialists perform diagnostic examinations involving a long, thin device known as a catheter. Except for its shape, the catheters used in the laboratory hardly resemble the catheters used for IVs.

A diagnostic examination involves three steps, said Melinda Durrange, RN, the laboratory supervisor:

By inserting a catheter into an artery (usually the femoral artery), lab personnel can guide the device through a patient’s body directly to a coronary artery. While inserted in a coronary artery, a catheter monitors blood pressure and the patient’s EKG during the diagnostic examination. Cardiac specialists even monitor blood pressure in various heart chambers. All this “gives us a pretty good indication of how the heart is functioning,” Durrange said;

Then a dye injected into the artery enters the bloodstream and “helps us to visualize the flow of the blood through the heart…to find the location of any blockages or other problems,” Johnson explained. This procedure is known as ventriculography (visualizing the dye flow through the heart).

In a scene straight out of futuristic medicine, monitoring equipment sends a comprehensive picture of the patient’s beating heart to a TV monitor in the lab. A camera mounted above the patient detects X-rays emitted by an imaging X-ray tube located beneath the patient.

Both the catheter and dye are video-opaque, meaning that “they can be seen on X-rays,” Durrange said.

The picture on the TV monitor unfolds as a black-and-white video, with the catheter clearly visible in an artery inside the pulsating heart. Lab personnel can even watch as dye spreads from the catheter into the bloodstream. Imaging equipment records the entire process on 35 mm. film and on cassette tape. The film affords long-term storage, while the cassette tape can be “used during the procedure to determine if they got all the information they needed,” said Durrange.

The video playing on the TV monitor has actually been magnified by an image intensifier so lab personnel can easily view the procedure;

Coronary angiography “actually involves looking for the location and extent of heart disease in the coronary arteries,” Durrange said.

“The information provided by this diagnostic exam plays an important role in the follow-up procedures recommended for the patient,” Johnson said. Those procedures vary from therapeutic procedures done in the laboratory to surgery performed in the Heart Center operating room.

Lab personnel often perform a therapeutic procedure known as balloon-angioplasty, a procedure available at EMMC only since October 1987. Once the diagnostic examination has located a blocked or constricted artery, cardiac specialists can insert a catheter directly to the affected point. Then a tiny, almost invisible balloon not much longer than a thumbnail is inflated and left in place for almost a minute. The balloon scrunches the artery-blocking plaque against the artery wall.

According to Johnson, this procedure essentially “cracks” the plaque and prevents it from regaining its former shape. With the blockage or constriction widened, blood again flows freely through the artery;

A coronary arterectomy differs substantially from balloon-angioplasty. In this procedure, a cardiac specialist guides a catheter to the blockage or constriction, then uses miniature knife at the catheter’s tip to scrape away the plaque. A “basket” attached to the catheter catches the removed plaque, which must not escape into the patient’s bloodstream.

Permanent pacemakers are installed in the cardiac-catheterization lab. Johnson estimated the number of procedures involving pacemaker installation at 75 annually.

Lab personnel also conduct EP (electrophysiology) studies “for patients with potential life-threating arrhythmias,” Johnson said. EP studies utilize a procedure in which different heart arrhythmias are induced in a patient. The EP studies determine which drugs and what drug dosages are most effective in controlling the patient’s particular arrhythmia.

Of course, cardiac surgery is also performed in the EMMC Heart Center. The procedures include coronary-artery bypass grafts, heart-valve replacements or repairs, and automatic implantable cardiac-fibrillator installations.

In the last procedure, which is performed on patients with arrhythmias uncontrollable by drugs, electrodes are sewn to the exterior of the heart. Wires lead from the electrodes to a box similar to a pacemaker. This box automatically defibrillates the heart if the patient suffers an arrhythmia.

Since the EMMC Heart Center opened in 1987, the number of patients being treated there has increased substantially. During the first year after the cardiac-catheterization lab opened, specialists performed balloon-angioplasty on 113 patients; that figure grew to 294 patients during the lab’s fourth year of operation.