What do SV (stroke volume) and ST (ST segment) mean in ECG (electrocardiogram) analysis?

From the Guidelines

In ECG analysis, SV stands for supraventricular and ST refers to the ST segment of the ECG waveform. Supraventricular (SV) indicates that the origin of electrical activity is above the ventricles, typically in the atria or AV node, and is used when describing arrhythmias like supraventricular tachycardia (SVT) 1. The ST segment represents the period between ventricular depolarization and repolarization, appearing as the flat line between the QRS complex and T wave. ST segment changes are crucial diagnostic indicators - elevation may suggest myocardial infarction or pericarditis, while depression might indicate ischemia or strain 1. When analyzing ECGs, clinicians pay particular attention to these elements as they provide vital information about cardiac electrical activity and potential pathologies. Understanding these abbreviations is essential for accurate ECG interpretation and appropriate clinical decision-making in cardiac care. Some key points to consider when interpreting ST segment changes include:

• Elevation of the ST segment in leads V1, V2, and V3 should be referenced against the elevation that occurs normally in these leads and is greater in young and middle-aged males than in females 1
• ST elevation is usually most pronounced in chest lead V2 1
• The upper normal limit for J-point elevation in V2 varies to a certain degree in various reference sources, probably largely as a result of differing selection criteria for the normal group 1
• Evaluation of ST elevation is of particular concern in connection with myocardial ischemia in acute myocardial infarction, as discussed in detail in part 6 of this series of recommendations (Acute Ischemia/Infarction) 1
• The threshold value for abnormal J-point elevation in V2 and V3 recommended in that part is 0.2 mV for men 40 years of age and older and 0.25 mV for men less than 40 years of age 1
• The recommended threshold value for adult women in V2 and V3 is 0.15 mV 1
• The threshold recommended for abnormal J-point elevation for men and women in all other standard leads is 0.1 mV 1
• ST-segment elevation can most often be attributed to 3 specific causes: 1) a normal variant, frequently referred to as early repolarization, commonly characterized by J-point elevation and rapidly upsloping or normal ST segment; 2) injury currents associated with acute ischemia or ventricular dyskinesis; and 3) injury currents usually associated with pericarditis 1
• Criteria exist to differentiate these causes and should be incorporated into the descriptive and diagnostic algorithms of the various computer-ECG algorithms 1
• However, it is important to recognize that in practice it is often difficult to differentiate between them 1
• In addition, a variety of other conditions may be associated with ST-segment elevation 1
• ST depression may be caused by various physiological, pathological, and pharmacological interventions that change the plateau phase of the ventricular action potential 1
• Examples include the effects of ischemia, hypokalemia, and a variety of cardiac and noncardiac drugs 1
• These are primary ST-segment changes 1
• Depression of the ST-segment also may occur concurrently with T-wave changes 1
• Examples include the ST-segment depression associated with hypertrophy and, as secondary repolarization abnormalities, in ventricular conduction disturbances 1
• The ST-segment changes on the standard ECG that are associated with acute ischemia or infarction are due to the flow of current across the boundary between the ischemic and nonischemic zones referred to as injury current 1
• ST-segment elevation generally occurs with reciprocal ST depression in ECG leads in which the axis is opposite in direction from those with ST elevation 1
• These ST-segment abnormalities are discussed in part VI (Acute Ischemia/Infarction), which gives 0.05 as the recommended threshold value for abnormal J-point depression in leads V2 and V3 in men and women and 0.1 mV in all other leads 1.

From the Research

ECG Analysis Terminology

• SV and ST are terms used in ECG (electrocardiogram) analysis to describe specific parts of the heart's electrical activity.
• ST refers to the ST segment, which is the flat section of the ECG waveform between the QRS complex and the T wave 2.
• The ST segment is important in diagnosing myocardial infarction (heart attack), as an elevated or depressed ST segment can indicate damage to the heart muscle.
• SV is not a standard term in ECG analysis, but it may refer to the SV1 and SV2 waves, which are part of the QRS complex in some ECG leads.

Clinical Significance

• Abnormalities in the ST segment, such as ST-segment elevation or depression, can indicate myocardial infarction or other heart conditions 2, 3.
• Left ventricular hypertrophy (LVH), which can be diagnosed using ECG and echocardiography, is associated with an increased risk of myocardial infarction and other cardiovascular diseases 3, 4.
• The use of ECG, coronary angiography, and other diagnostic tests can help identify patients at risk of myocardial infarction and guide treatment decisions 5, 2.