possible to take this momentum back to Purkinje fibers along the vessels of the myocardium. This idea is also proved by the fact that hypertrophy of the left ventricle, myocardial ischemia, coronary and insufficiency have momentum there is no possibility to move to the Purkinje fibers, therefore, the ECG recorded a negative U wave. Interpretation According to many studies, U waves often register in all leads except V6, most frequently in V2 and V3 when the heart rate is greater than 96 beats per minute. Its amplitude is often 0.1–0.33 mV. Particularly difficult is the allocation of the boundaries of the U wave on the background of the T wave and R wave, which may partial or complete (in the case of T wave) the merger. Higher values of heart rate or hypocalcemia U wave are superimposed on the T wave and in tachycardia — merges with the R-wave of the next cardiac cycle. Prominent U waves (U waves are described as prominent if they are more than 1-2 mm or 25% of the height of the T wave.) are most often seen in hypokalemia but may be present in hypercalcemia, thyrotoxicosis, or exposure to digitalis, epinephrine and Class 1A and 3 antiarrhythmics, as well as in congenital long QT syndrome, and in the setting of intracranial hemorrhage. An inverted U wave may represent myocardial ischemia (and especially appears to have a high positive predictive accuracy for left anterior descending coronary artery disease ) or left ventricular volume overload. A U-wave can sometimes be seen in normal younger, athletic individuals. The U-wave increases in adults that are older and less athletic. References Cardiac electrophysiology