Medical Mystery of the Week

      You are asked to interpret a simultaneous recording of a patient's blood pressure and EKG (shown below). How do you interpret each recording (i.e., what are your diagnoses)?               DIAGNOSES: EKG - Right atrial hypertrophy. BP - Pulsus alternans.

       In the above figure note the peaking of the P waves, a sign of right atrial hypertrophy, and the variation in the systolic blood pressure with each heart beat which is characteristic of pulsus alternans. Deflating the blood pressure cuff from ∼160 mm Hg to ∼ 140 mm Hg doubles the heart rate.

      Pulsus alternans is most commonly seen in patients with severe left ventricular dysfunction due to cardiomyopathy, coronary artery disease, hypertensive heart disease, or aortic stenosis. The presented case, however, has right ventricular pulsus alternans. Right ventricular pulsus alternans is associated with increased pulmonary vascular resistance due to reactive airway disease, COPD, pulmonary embolism, idiopathic pulmonary hypertension, or Eisenmenger's syndrome.

BONUS QUESTION ANSWER: Dermatographia. Dermatographia is an exaggerated axonal response to light stroking of the skin. Reverse dermatographia (blanching of the skin with light stroking) may be seen in persons with eczema.