Heart Attack Treatment (cont.)
Daniel Lee Kulick, MD, FACC, FSCAI
Dr. Kulick received his undergraduate and medical degrees from the University of Southern California, School of Medicine. He performed his residency in internal medicine at the Harbor-University of California Los Angeles Medical Center and a fellowship in the section of cardiology at the Los Angeles County-University of Southern California Medical Center. He is board certified in Internal Medicine and Cardiology.
In this Article
- What is a heart attack?
- How is a heart attack treated?
- Antiplatelet agents
- Glycoprotein IIb/IIIa inhibitors
- Clot-dissolving drugs
- Coronary angiography and percutaneous transluminal coronary angioplasty (PTCA)
- Coronary artery stents
- Angiotensin converting enzyme (ACE) inhibitors
- Beta blockers
- Coronary artery bypass
- What can a patient expect during recovery from a heart attack?
- How can a second heart attack be prevented?
- Find a local Cardiologist in your town
While antiplatelet agents and anticoagulants prevent the formation of blood clots, they cannot dissolve existing blood clots and hence cannot be relied upon to open blocked arteries rapidly. Clot-dissolving drugs (also called fibrinolytic or thrombolytic medications) actually dissolve blood clots and can rapidly open blocked arteries. Intravenous administration of clot-dissolving drugs such as tissue plasminogen activator (TPA) or TNK can open up to 80% of acutely blocked coronary arteries. The earlier these drugs are administered, the greater the success at opening the artery and the more effective the preservation of heart muscle. If clot-dissolving drugs are given too late (more than 6 hours after the onset of the heart attack), most of the muscle damage already may have occurred.
If a hospital does not have a catheterization laboratory with the ability to perform PTCA, or if there are logistic reasons why PTCA will be delayed, clot-dissolving drugs can be promptly administered to achieve reperfusion. PTCA then may be performed in patients who fail to respond to the clot-dissolving drugs. (If prompt PTCA and stenting are available, it has been demonstrated that they are preferable to clot-dissolving drugs to open arteries.)
Clot-dissolving drugs increase the risk of bleeding enough so that some patients cannot be treated with them, for example, patients with recent surgery or major trauma, recent stroke, bleeding ulcer, or other conditions that increases the risk of bleeding.
Coronary angiography and percutaneous transluminal coronary angioplasty (PTCA)
Coronary angiography and percutaneous transluminal coronary angioplasty (PTCA) is the most direct method of opening a blocked coronary artery. The procedures are performed in the catheterization laboratory in a hospital. Under X-ray guidance, a tiny plastic catheter with a balloon on its end is advanced over a guide wire from a vein in the groin or the arm and into the blocked coronary artery. Once the balloon reaches the blockage, it is inflated, pushing the clot and plaque out of the way to open the artery. PTCA can be effective in opening up to 95% of arteries. In addition, the angiogram (X-ray pictures taken of the coronary arteries) allows evaluation of the status of the other coronary arteries so that long-term treatment plans may be formulated.
For optimal benefits, coronary angiography and PTCA should be performed as soon as possible. Most cardiologists recommend that the time interval between the patient's arrival at the hospital and the deployment of the angioplasty balloon to open the artery should be less than 60 to 90 minutes.
For best results, the coronary angiogram and PTCA should be performed by an experienced cardiologist in a well-equipped cardiac catheterization laboratory. The cardiologist is considered experienced if he or she performs more than 75 such procedures a year. The catheterization laboratory personnel are considered experienced if the facility performs more than 200 such procedures a year.
It also is important that there be a surgical team to perform immediate open-heart surgery (coronary artery bypass grafting) in the event that PTCA is unsuccessful in opening the blocked artery or if there is a serious complication of PTCA. For example, in a small number of patients, PTCA cannot be performed because of technical difficulties in passing the guide wire or the balloon across the narrowed arterial segment. Open-heart surgery also will be necessary if there is a serious complication such as coronary artery injury during PTCA or an abrupt closure of the coronary artery shortly after PTCA. These complications may occur in a small percentage of patients.
The most serious complication of PTCA is an abrupt closure of the coronary artery within the first few hours after PTCA. Abrupt coronary artery closure (that can lead to further heart damage) occurs in some patients after simple balloon angioplasty (without stenting). Abrupt closure is due to a combination of tearing (dissection) of the inner lining of the artery, blood clotting at the site of the balloon, and constriction (spasm) or elastic recoil of the artery at the site where the balloon is inflated. Individuals at an increased risk for abrupt closure include women, patients with unstable angina, and patients having heart attacks.
The risk of abrupt closure of the coronary arteries can be reduced if:
- Aspirin is given during or after PTCA to prevent blood clotting. In fact, virtually all patients are maintained on aspirin indefinitely after PTCA to prevent arterial clots.
- Anticoagulants such as intravenous heparin or bivalirudin are given during PTCA to further prevent blood clotting.
- Combinations of nitrates and calcium channel blockers are used to minimize coronary artery spasm (see discussion that follows).
- Coronary artery stents are deployed to minimize coronary artery closure.
- The glycoprotein IIb/IIIa inhibitors are given.
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