1. Health
Send to a Friend via Email

Coronary Artery Disease and Angina

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of CAD.

Alternative Names

Angina; Angiography; Angioplasty; Atherosclerosis; Beta Blockers; Calcium Channel Blockers; Coronary Artery Bypass Surgery; Coronary Artery Disease

Angioplasty and Stents

Percutaneous transluminal coronary angioplasty (PTCA), usually simply called angioplasty, involves opening the blocked artery.

A typical angioplasty procedure follows the following steps:
  • The surgeon threads a narrow catheter (a tube) containing a fiber optic camera directly to the blocked vessel.
  • The physician opens the blocked vessel using balloon angioplasty, in which the surgeon passes a tiny deflated balloon through the catheter to the vessel.
  • The balloon is inflated to compress the plaque against the walls of the artery, flattening it out so that blood can once again flow through the blood vessel freely.
  • In order to keep the artery open afterwards, surgeons now most often employ a device called a coronary stent, which is an expandable metal mesh tube that is implanted during angioplasty at the site of the blockage. (A stent may be used as the initial opening device, in some cases, instead of balloon angioplasty. It is not yet clear if this approach is significantly more beneficial than PTCA plus optional stenting.)
Coronary artery stent
Null
  • Once in place, the stent pushes against the wall of the artery to keep it open.

Complications occur in about 10% of patients (about 80% within the first day). In one report of 53 European and Canadian medical centers, the mortality rate from all causes four years after PTCA was 4.1% Outcomes are better in hospital settings with experienced teams and backup.

Coronary artery balloon angioplasty - seriesClick the icon to see an illustrated series detailing coronary artery balloon angioplasty surgery.

The most important long-term complication is reclosure (restenosis), which can lead to heart attack if not treated with a repeat procedure. Stenting and other advances have helped significantly in preventing reclosure and reducing heart attack rates. Nevertheless, a repeat procedure is still needed to restore the opening in 10% to 15% of procedures that use stents. Radiation therapies and stents coated with immunosuppressive agents may significantly reduce these rates.

Recuperation

Angioplasty is less invasive than bypass surgery, requiring only one night in the hospital. Recuperation takes about a week. It should be pointed out the chest pain after the procedure is very common and usually due to problems other than ischemia. Mild chest pain is even more common when a stent is used, possibly because the artery is stretched.

Preventing Reclosure and Blockage During or Shortly after Angioplasty

Reclosure of the artery during or shortly after angioplasty often occurs. A number of anti-clotting agents are used to help prevent this, although they are not wholly protective because reclosure in some cases is due to other, unknown causes.

  • Aspirin and the anti-platelet agent clopidogrel are often used to prevent reclosure during the procedure.
  • A high dose of the anticoagulant heparin is typically given before the operation.
  • Intravenous glycoprotein IIb/IIIa inhibitors, powerful agents that block platelets, also prevent reclosure after stenting in many high-risk patients, and evidence now strongly suggests that they reduce rates of heart attack and death. Eptifibatide (Integrilin) and tirofiban (Aggrastat) are the standard agents used during angioplasty. They may be most effective if administered during angioplasty, rather than beforehand.

All of these agents, pose a risk for bleeding complications.

Preventing Artery Narrowing (Restenosis) Over Time

Narrowing or reclosing of the artery (restenosis) can occur within a year of angioplasty or even longer in between 15% and 60% of angioplasty patients. Coronary stents, anti-clotting agents, and other advances have reduced these events significantly, but have not eliminated the problem. Theories for the cause of restenosis include the following:

  • The release of oxidants (damaging unstable particles) at the surgical site may cause injury and activate immune factors that produce cellular overgrowth in smooth muscles of the blood vessels.
  • Other activities, including scarring, may remodel and narrow the blood vessels. (This is most likely the reason for restenosis in stented patients.)

Symptoms of restenosis include chest pain on exertion. (Heart attacks, however, do not usually occur with such events.) The narrowing of the artery in this case is not due to blood clots and so anti-clotting agents are not useful. Restenosis usually requires a repeat operation. A number of approaches, mostly investigative, have been developed to prevent restenosis after angioplasty.

Sirolimus- and Other Drug-Coated Stents. Stents coated with the drug sirolimus (Rapamune), also called rapamycin, are generating great excitement. This agent dampens immune factors that cause cell proliferation and inflammation and it also has antibiotic properties. In an important 2002 study, none of the patients who were given the coated stent experienced reclosure and 94% of them were free of any adverse heart events. In comparison, 27% of patients in the noncoated group experienced restenosis and only 71% of them were free of adverse heart events. Although long-term side effects remain unknown, some experts believe this advance will revolutionize heart treatments. Other drug coatings under investigation include paclitaxel.

Coronary Artery Brachytherapy. Radiation treatment called coronary artery brachytherapy (Gamma One, Beta-Cath) can inhibit cell growth in the arteries responsible for restenosis. With this approach, any blockage in the stent is first removed, and a tube with an inflatable balloon is inserted. The surgeon then implants a temporary device that delivers radiation. Brachytherapy is showing excellent results in preventing restenosis and significantly reducing heart events and improving survival. Brachytherapy is also showing promise in preventing restenosis in stented artery grafts that were put in place after bypass surgery and later failed.

There are still many outstanding safety issues with these treatments, however, that will only be answered with long-term use. For example, one 2002 study reported a possibly higher risk for blood clotting. It should be noted that once radiation is performed, stents cannot be replaced again.

Medications. A number of medications are being studied for prevention of restenosis, although benefits to date have been modest. Other agents under investigation include statins, various anti-clotting agents, and B vitamins.

Other Procedures. Other procedures under investigation to keep the arteries open use ultrasound "soft" x-rays, and cryotherapy (very low temperatures).

adam.com

©2014 About.com. All rights reserved.