Search results
Results from the WOW.Com Content Network
It can be difficult to distinguish unstable angina from non-ST elevation (non-Q wave) myocardial infarction. [4] [5] They differ primarily in whether the ischemia is severe enough to cause sufficient damage to the heart's muscular cells to release detectable quantities of a marker of injury, typically troponin T or troponin I.
Strenuous endurance exercise such as marathons or triathlons can lead to increased troponin levels in up to one-third of subjects, but it is not linked to adverse health effects in these competitors. [27] [28] [29] High troponin T levels have also been reported in patients with inflammatory muscle diseases such as polymyositis or dermatomyositis.
Angina results when there is an imbalance between the heart's oxygen demand and supply. This imbalance can result from an increase in demand (e.g., during exercise) without a proportional increase in supply (e.g., due to obstruction or atherosclerosis of the coronary arteries).
Depending on the marker, it can take between 2 and 24 hours for the level to increase in the blood. Additionally, determining the levels of cardiac markers in the laboratory - like many other lab measurements - takes substantial time. Cardiac markers are therefore not useful in diagnosing a myocardial infarction in the acute phase.
Variant angina is caused by vasospasm, a narrowing of the coronary arteries due to contraction of the heart's smooth muscle tissue in the vessel walls. [3] In comparison, stable angina is caused by the permanent occlusion of these vessels by atherosclerosis, which is the buildup of fatty plaque and hardening of the arteries. [4]
Acute coronary syndrome is subdivided in three scenarios depending primarily on the presence of electrocardiogram (ECG) changes and blood test results (a change in cardiac biomarkers such as troponin levels): [4] ST elevation myocardial infarction (STEMI), non-ST elevation myocardial infarction (NSTEMI), or unstable angina. [5]
Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!
The level of the troponin, as well as a change over time, are useful in measuring and diagnosing or excluding myocardial infarctions, and the diagnostic accuracy of troponin testing is improving over time. [72] One high-sensitivity cardiac troponin can rule out a heart attack as long as the ECG is normal. [83] [84]