There are numerous potential clinical uses of the 12-lead ECG. The ECG may reflect changes associated with primary or secondary myocardial processes (e.g., those associated with coronary artery disease, hypertension, cardiomyopathy, or infiltrative disorders), metabolic and electrolyte abnormalities, and therapeutic or toxic effects of drugs or devices. Electrocardiography serves as the gold standard for the noninvasive diagnosis of arrhythmias and conduction disturbances, and it occasionally is the only marker for the presence of heart disease.
Marfan syndrome is currently diagnosed using criteria based on an evaluation of the family history, molecular data, and 6 organ systems.
Aortic valve stenosis is usually defined by restricted systolic opening of the valve leaflets, with a mean transvalvular pressure gradient of at least 10 mm Hg.
Chagas’ disease is caused by a protozoan parasite, Trypanosoma cruzi, that is transmitted to humans through the feces of infected bloodsucking insects in endemic areas of Latin America, or occasionally by nonvectorial mechanisms, such as blood transfusion. Cardiac involvement, which typically appears decades after the initial infection, may result in cardiac arrhythmias, ventricular aneurysm, congestive heart failure, thromboembolism, and sudden cardiac death.
Percutaneous coronary interventions (PCI) include percutaneous transluminal coronary angioplasty (PTCA) with or without stenting. Primary indications are treatment of angina pectoris (stable or unstable), myocardial ischemia, and acute MI (particularly in patients with developing or established cardiogenic shock).
In addition to the prediction of cardiovascular risk, ambulatory blood-pressure monitoring, when used in conjunction with clinic blood-pressure assessments, is of potential value in a variety of other clinical conditions. Some of these conditions are:
Clinical Predictors of Increased Perioperative Cardiovascular Risk (Myocardial Infarction, Heart Failure, Death)
Unstable coronary syndromes
- Acute or recent MI* with evidence of important ischemic risk by clinical symptoms or noninvasive study
- Unstable or severe† angina (Canadian class III or IV) Continue reading
Myocarditis may present with a wide range of symptoms, ranging from mild dyspnea or chest pain that resolves without specific therapy to cardiogenic shock and death. Dilated cardiomyopathy with chronic heart failure is the major long-term sequela of myocarditis. Most often, myocarditis results from common viral infections; less commonly, specific forms of myocarditis may result from other pathogens, toxic or hypersensitivity drug reactions, giant-cell myocarditis, or sarcoidosis. Continue reading
There are two criteria with these widely used indices:
* Sum of S wave in V1 and R wave in V5 or V6 >/= 3.5 mV (35 mm)
* R wave in aVL >/= 1.1 mV (11 mm)