Ischemic Heart Disease
- causes and risk factors
- signs and symptoms
- pathophysiology
- treatments
- consequences and course
- health care team
- the patient
- community involvement
- references
Causes and Risk Factors
Ischemic heart disease results from an imbalance between perfusion (supply) and workload (demand) of the heart. Ischemia not only involves oxygen insufficiency, but also reduced nutrient concentration and inadequate removal of metabolites.
In more than 90% of cases, ischemia is due to atherosclerosis. For this reason, ischemic heart disease is often termed coronary artery disease.
Risk of developing IHD depends on number, distribution, and size of plaques.
Signs and Symptoms
A fixed obstruction of coronary arteries will generally cause symptoms with exercise, while a 90% stenosis will lead to symptoms at rest.
Ischemic heart disease can appear in four ways:
acute coronary syndromes, such as myocardial infarction
chronic IHD and heart failure
Pathophysiology
Atherosclerosis begins in childhood. Clinically significant plaques tend to be present eithin the first several centimeters of the LAD and LCX and along the entire length of the RCA. On occasion, the major secondary epicardial branches are involved - the diagonal branches of the LAD, obtuse marginal branches of the LCX, or posterior descending branch of the RCA.
IHD can be increased by cardiac hypertrophy, diminished oxygen supply (anemia, shock, etc), or with increased heart rate.
Athrosclerotic narrowing of the epicardial coronary arteries, together with thrombosis, platelet aggregation, and vasospasm, all contribute to IHD.
Within seconds, aerobic glycolysis stops and lactic acid begins to breakdown. A striking loss of contractility occurs within 60 seconds of ischemia onset, which can precipitate heart failure long before infarction. Only severe ischemia lasting 20-40 minutes leads to cell death, however.
Treatments
Consequences and Course
The Patient
Community Involvement
References