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ST and T abnormalities.ppt
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Скачать презентацию ST and T abnormalities Long QT Interval
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ST and T abnormalities
Long QT Interval and Giant Negative T Waves
Long QT Interval • The QT interval duration is greater than 50% of the RR interval, a good indication that it is prolonged in this patient. Although there are many causes for the long QT, patients with this are at risk for malignant ventricular arrhythmias, syncope, and sudden death.
Long QT Interval
Normal Variant: Early Repolarization • Early repolarization, a misnomer, describes a pattern of localized or diffuse ST segment elevation. This is especially seen in leads with prominent R waves. In this example leads I, II, V 5 and V 6 illustrate the early repolarization pattern. ST segments usually have a "concave upwards" pattern and take off after a small S-wave is inscribed
ST Segment Depression • ST segment depression is a nonspecific abnormality that must be evaluated in the clinical context in which it occurs. In a patient with angina pectoris ST depression usually means subendocardial ischemia and, unlike ST elevation, is not localizing to a particular coronary artery lesion.
Inferolateral ST Segment Elevation • ST Segment elevation with a straight or convex upwards configuration usually means transmural ishemia (or injury) and is seen in the setting of acute myocardial infarction. This ECG finding may also be seen transiently during coronary artery spasm. Unlike ST depression, ST elevation is often localizing. In this example of inferolateral ST elevation, the culprit artery is often a dominant right coronary artery or dominant left circumflex artery.
Long QT: An ECG Marker For Sudden Cardiac Death
Hyperkalaemia • The following changes may be seen in hyperkalaemia • small or absent P waves • atrial fibrillation • wide QRS • shortened or absent ST segment • wide, tall and tented T waves • ventricular fibrillation
Hyperkaliemia
Hyperkalemia and Old Inferior MI • The T waves are tall, peaked and have a narrow base, making them very uncomfortable to sit on! These changes are characteristic of hyperkalemia. The QRS is also slightly widened, another feature of hyperkalemia. Q waves in III and a. VF indicate an old inferior MI
Advanced Hyperkalemia • Marked widenening of the QRS duration combined with tall, peaked T waves are suggestive of advanced hyperkalemia. Note the absence of P waves, suggesting a junctional rhythm, but in hyperkalemia the atrial muscle may be paralyzed while still in sinus rhythm. The sinus impulse conducts to the AV node through internodal tracts without activating the atrial muscle.
Hypokaliemia • Hypokalaemia • • The following changes may be seen in hypokalaemia. • small or absent T waves • prominent U waves (see diagram) • first or second degree AV block • slight depression of the ST segment
Giant TU Fusion Waves • TU fusion waves are often seen in long QT syndromes. The differential diagnosis of this ECG abnormality includes electrolyte abnormalities -hypokalemia, CNS disease, e. g. , subarrachnoid hemorrhage; hereditary long QT syndromes, and drugs such as quinidine.
Hypothermia: J-waves or Osborne Waves • In hypothermia, a small x-tra wave is seen immediately after the QRS complex (best seen in Lead I in this example). This x-tra wave is called a J-wave, or Osborne wave after the individual who first described it. This wave disappears with warming of body temperature. The mechanism is unknown.
Digitalis effect • shortened QT interval • characteristic down-sloping ST depression, reverse tick appearence, (shown here in leads V 5 and V 6) • dysrhythmias – – • ventricular / atrial premature beats paroxysmal atrial tachycardia with variable AV block ventricular tachycardia and fibrillation many others
Скачать презентацию ST and T abnormalities Long QT Interval
ST and T abnormalities.ppt