Review Question - QID 105386

This patient is presenting with signs and symptoms of hyperkalemia in the setting of being non-compliant with his dialysis. Hyperkalemia presents as peaked T-waves, shortened QT interval first. As the severity of hyperkalemia increases, PR lengthening, and widened QRS can be seen on EKG.

Hyperkalemia can be due to a decreased or impaired ability to excrete potassium (as can be seen in renal failure), increasing potassium in the extracellular space (i.e., hemolysis, rhabdomyolysis, oral or intravenous potassium), shifting potassium from the intercellular to extracellular space (i.e., digitalis toxicity, beta-blockers), and much more. Elevated levels of potassium in the extracellular space can increase the resting membrane potential (make it less electronegative) of myocytes and cardiomyocytes, partially depolarizing the cell membrane. When a persistent depolarization ensues, sodium channels are inactivated, decreasing membrane excitability. This leads to cardiac conduction impairment and neuromuscular weakness/paralysis. Hyperkalemia is also associated with ileus. End-stage renal disease patients are at increased risk of developing hyperkalemia. In this patient, non-compliance with his dialysis treatment increases his risk of developing cardiac arrhythmia.

Hollander-Rodriguez and Calvert present a review on hyperkalemia. Intravenous calcium is effective at decreasing the risk of arrhythmia, and reversing the electrocardiographic changes on EKG. Intravenous calcium stabilizes the myocardium, thus decreasing the risk of arrhythmia. IV insulin and glucose, and beta-2 agonists (i.e., nebulized albuterol) can be used to lower the serum potassium level by shifting the potassium inside the cell. Polystyrene sulfonate (Kayexalate) aids in gastrointestinal excretion of potassium.

Putcha and Allon discuss the management of hyperkalemia in patients on dialysis. In patients with end-stage renal disease, dialysis is the definitive treatment of hyperkalemia. Dietary compliance, and avoiding medications that may result in hyperkalemia are important in the prevention of hyperkalemia.

Figure A demonstrates peaked T-waves in precordial lead V5.

Incorrect Answers
Answer 1: Progressive PR prolongation, followed by a 'drop' in QRS describes a Mobitz type I second-degree AV heart block.
Answer 2: S wave in lead I, Q wave in lead III, and inverted T wave in lead III are suggestive of a pulmonary embolism (PE). However, most patients with PE do not present with this electrocardiographic finding.
Answer 3: ST-segment elevation in leads II, III, and aVF describes an inferior wall myocardial infarction.
Answer 5: Diffuse PR segment depression and ST-segment deviations are suggestive of pericarditis.