Cardiology Demo 2

ECG is the process of recording the electrical activity of the heart over a short period of time using electrodes placed on the skin. These electrodes detect the tiny electrical changes on the skin that arise from the heart muscle’s electrophysiologic pattern of depolarization and repolarization during each heartbeat. It is very commonly performed to detect any cardiac problems.

In a conventional 12-lead ECG, four electrodes are placed on the patient’s limbs and six electrodes on the chest wall. The overall magnitude of the heart’s electrical potential is then measured from twelve different angles (“leads”) and is recorded over a period of time (usually ten seconds). In this way, the overall magnitude and direction of the heart’s electrical depolarization is captured at each moment throughout the cardiac cycle. The graph of voltage versus time produced by this noninvasive medical procedure is an electrocardiogram.

During each heartbeat, a healthy heart has an orderly progression of depolarization that starts with pacemaker cells in the sinoatrial node, spreads out through the atrium, passes through the atrioventricular node down into the bundle of His and Purkinje fibers, spreading down and to the left throughout the ventricles. This orderly pattern of depolarization gives rise to the characteristic ECG tracing. To the trained clinician, an ECG conveys a large amount of information about the diseases of the structure of the heart and the function of its electrical conduction system. Among other things, an ECG can be used to measure the rate and rhythm of heartbeats, the size and position of the heart chambers, the presence of any damage to the heart’s muscle cells or conduction system, the effects of cardiac drugs, and the function of implanted pacemakers.

Medical Uses Of ECG:

The overall goal of performing electrocardiography is to obtain information about the structure and function of the heart. Medical uses for this information are varied and generally relate to having a need for knowledge of the structure and/or function. Some indications for performing electrocardiography include:

• Suspected myocardial infarction (heart attack) or chest pain.
• Suspected pulmonary embolism or shortness of breath
• A third heart sound, fourth heart sound, a cardiac murmur or other findings to suggest structural heart disease
• Perceived arrhythmia either by pulse or palpitations
• Monitoring of known cardiac dysrhythmias
• Fainting or collapse
• Seizures
• Monitoring the effects of a heart medication (e.g. drug-induced QT prolongation)
• Assessing severity of electrolyte abnormalities, such as hyperkalemia
• Hypertrophic cardiomyopathy screening in adolescents as part of sports medicine to avoid sudden cardiac death (varies by country)
• Perioperative monitoring in which any form of anesthesia is involved (e.g. monitored anesthesia care, general anesthesia); typically preoperative, intraoperative and postoperative
• As a part of a pre-operative assessment some time before a surgical procedure (especially for those with known cardiovascular disease or who are undergoing invasive or cardiac, vascular or pulmonary procedures, or who will receive general anesthesia)
• Cardiac stress
• Computed Tomography Angiography (CTA) and Magnetic Resonance Angiography (MRA) of the heart (ECG is used to “gate” the scanning so that the anatomical position of the heart is steady).

An Echocardiogram, often referred to as a cardiac echo or simply an echo, is a sonogram of the heart. (It is not abbreviated as ECG, because that is an abbreviation for an electrocardiogram.) Echocardiography uses standard two-dimensional, three-dimensional, and Doppler ultrasound to create images of the heart.

Echocardiography has become routinely used in the diagnosis, management, and follow-up of patients with any suspected or known heart diseases. It is one of the most widely used diagnostic tests in cardiology. It can provide a wealth of helpful information, including the size and shape of the heart (internal chamber size quantification), pumping capacity, and the location and extent of any tissue damage. An echocardiogram can also give physicians other estimates of heart function, such as a calculation of the cardiac output, ejection fraction, and diastolic function (how well the heart relaxes).

Echocardiography can help detect cardiomyopathies, such as hypertrophic cardiomyopathy, dilated cardiomyopathy, and many others. The use of stress echocardiography may also help determine whether any chest pain or associated symptoms are related to heart disease. The biggest advantage of transthoracic echocardiography is that it is not invasive (does not involve breaking the skin or entering body cavities) and has no known risks or side effects.

Not only can an echocardiogram create ultrasound images of heart structures, but, it can also produce accurate assessment of the blood flowing through the heart by Doppler echocardiography, using pulsed-or continuous-wave Doppler ultrasound. This allows assessment of both normal and abnormal blood flow through the heart. Color Doppler, as well as spectral Doppler, is used to visualize any abnormal communications between the left and right sides of the heart, any leaking of blood through the valves (valvular regurgitation), and estimate how well the valves open (or do not open in the case of valvular stenosis). The Doppler technique can also be used for tissue motion and velocity measurement, by tissue Doppler echocardiography.

Echocardiography was also the first ultrasound subspecialty to use intravenous contrast. Echocardiography is performed by cardiac sonographers, cardiac physiologists, or physicians trained in echocardiography.

Medical Uses :

Health societies recommend the use of echocardiography for initial diagnosis when a change in the patient’s clinical status occurs and when new data from an echocardiogram would result in the physician changing the patient’s care. Health societies do not recommend routine testing when the patient has no change in clinical status or when a physician is unlikely to change care for the patient based on the results of testing.

A common example of overuse of echocardiography when not indicated is the use of routine testing in response to a patient diagnosis of mild valvular heart disease. In this case, patients are often asymptomatic for years before the onset of deterioration and the results of the echocardiogram would not result in a change in care without other change in clinical status.