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Cases | Cardiothoracic | Earl
Following the examination Dr. Grey obtained the following tests:
Which of the following does the EKG inidicate as a couse for Edith's symptom??
a. Ischemia b. Heart block c. Compensatory pause d. Premature atrial contraction
The correct answer is c. The wide QRS complex coming after a shortened RR interval followed by a long compensatory pause characterizes a premature ventricular contraction or PVC. The compensatory pause gives rise to the sensation of the heart stopping or "standing still." The beat following the pause exhibits post-extra systolic potentiation, or a forceful contraction, often experienced by the patient as a "thump." Premature atrial contractions are different from PVCs in that they are generally preceeded by a premature p wave and are not followed by a compensatory pause.
The lyric by Lorenz Hart, "I took one look at you, that's all I had to do, and my heart stood still," from the song, "My Heart Stood Still," emphasizes the relationship of PVCs to emotion and other adrenergic stimuli, such as caffeine, that cause depolarization of ventricular purkinje cells.
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