Coronary artery disease (CAD) is one of the most preventable of all diseases yet it affects almost 13 million Americans, making it the most common form of heart disease. In the US about 1.5 million heart attacks occur annually. According to the World Health Organization an estimated 17.5 million people died from cardiovascular disease in 2005. Complications of CAD such as angina, heart attack, and irregular heart rhythms are leading causes of death for both men and women in the United States. Treatments are aimed at controlling symptoms and slowing or stopping the progression of CAD. For patients, it is imperative to know what types of treatment options are available. Patients possessing knowledge of available treatment options will have a tremendous advantage toward a successful outcome.
Risk factors for CAD include, but are not limited to: hypertension, elevated blood sugar, and high cholesterol levels leading to hardening of the artery. These causes can lead to a buildup of material that forms inside the arteries of the cardiovascular system. In the case of CAD this build up, known commonly as plaque, is in the arteries of the heart. Coronary artery plaques generally consist of cholesterol, fatty compounds, calcium and in some cases immune response cells. As plaque builds in the artery, the pathway of blood narrows, whereby limiting blood flow.
In recent years physicians have found that there are two basic kinds of plaque: hard and soft. Hard plaque gradually builds up inside the artery wall over time slowing or stopping blood flow to the heart muscle and possibly causing chest pain, known as angina. Soft plaque, also known as a vulnerable plaque, is a type of fatty buildup in an artery thought to be initiated by inflammation. A thin fibrous cap covers the soft plaque that may rupture and lead to the formation of a blood clot. As the clot grows, it will ultimately occlude the artery and could cause a heart attack. Research has shown that although hard plaques can cause some heart attacks, most heart attacks are caused by soft plaques.
When patients enter the emergency department exhibiting signs or symptoms indicating a heart attack, they should be immediately assessed and treated according to medical standards of care. These standards of care for patients exhibiting cardiac symptoms include certain initial tests such as an EKG and blood work, and treatments such as administering oxygen and nitroglycerin. Both the American College of Cardiology and the American Heart Association acknowledge that symptom recognition and speed of response is vital, particularly in cases where the patient may have already had a previous cardiac arrest, to maximize the chances of survival. After the onset of heart attack symptoms it is strongly recommended that patients receive treatment as soon as possible to open the affected coronary artery.
For those patients in the midst of a heart attack, also medically termed myocardial infarction, percutaneous coronary intervention (PCI) has been shown to be superior to any other treatment option for quick assessment and treatment of the affected coronary artery (3). Patients that are transported to facilities that offer the ability to perform a PCI within a short time have a dramatic advantage over those patients who do not have this immediate option. This is due to the fact that during a heart attack, the heart muscle or myocardium is starving for oxygen rich blood and total occlusion of a coronary artery for durations of more than 4-6 hours results in irreversible heart damage. Opening the blockage within this small window of time can salvage the affected area of the heart and improve a patients chance of survival.
Percutaneous coronary intervention was pioneered in the late 1970s and is a non-surgical procedure performed in a cardiac catheterization laboratory under local anesthetic, mild to moderate sedation, and pain medication. During a PCI the coronary arteries are accessed through a small incision made in the femoral artery, located in the patients groin area. The groin is the most common site for PCI procedures; however the radial and brachial arteries of the arm may also be used. A small plastic sheath is then inserted through the artery to protect the vascular system and flexible catheters are passed through the sheath to the heart. An iodine-based dye or other contrast agent is injected into the affected arteries through a small catheter allowing an x-ray image of the arteries to be visible on a monitor. Physicians will then use the monitor image as a guide during the procedure to perform an angioplasty, which is the inflation of a tiny balloon inside the coronary artery to displace the blockage.
Research has shown that in the instance of a heart attack the best PCI results occur when the procedure is conducted within 90 minutes of the time of arrival to the treatment facility. Beyond this critical response period for patients not having a life-threatening heart attack, medications, elective PCI, or coronary artery bypass graft surgery (CABG) may be the best option. Further diagnostic testing may be required for non-critical patients to more accurately diagnose CAD and determine appropriate treatment.
In some instances during a PCI extra measures must be taken to maintain an open artery. A small hollow metal spring-like device called a "stent" is placed at the blockage location. Stents can be deployed over the angioplasty balloons and are then left within the coronary arteries of the heart to help keep them free of plaque blockage. Stents help prevent abrupt closure of arteries shortly after angioplasty. Stents also prevent recurrent narrowing of the coronary artery and decrease the risks of the arterial vessel tearing or rupture, elastic recoil, and arterial spasm, all of which can occur after PCI procedures. The widespread use of coronary stents has reduced the incidence of repeat occlusion of the artery by as much as 50%. There also has been a recent introduction of coated stents also know as drug eluting stents, which are coated with chemicals to further reduce the chance of developing another blood clot in the same location. These newer drug eluding stents have been shown to reduce the incidence of coronary artery re-occlusion to well under 10% and have been a major improvement in treatment. Some of the risks involved in having the PCI completed include bleeding at the insertion site, abnormal heart rhythms, infection, kidney failure, stroke, and ruptured artery.
Research in the field of cardiovascular medicine is constant and treatment standards with research continue to change and improve. Since each case is unique only physicians and patients together can decide which treatment option is the best for that individual.
This article is the first part in a two part series on coronary artery disease and the treatments available.
Heidi Starr, RN, BSN, is a cardiac catheterization lab registered nurse at Mount Nittany Medical Center.