Tall-tented T waves and widened QRS are seen in?

Appeared in: JODHPUR AIIMS SNO-2018

Explanation

Hyperkalemia is defined as a serum potassium level greater than 5.0-5.5 mEq/L.
Elevated extracellular potassium alters the resting membrane potential of cardiac myocytes, affecting both depolarization and repolarization.
This alteration manifests on the ECG as tall, peaked (tented) T waves due to accelerated repolarization.
The same process slows ventricular conduction, leading to a widened QRS complex.
The combination of these two findings is a hallmark of hyperkalemia and indicates a high risk of life-threatening cardiac arrhythmias.

Option A: Hyperphosphatemia does not cause tall-tented T waves or a widened QRS. Its primary ECG effect is related to the reciprocal hypocalcemia it often causes.
Option C: Hyponatremia is not characterized by tall-tented T waves. While very severe cases can cause some QRS widening, it is not a classic or expected finding.
Option D: Hyperglycemia itself does not directly alter the ECG in this manner. The ECG changes are caused by the associated electrolyte shifts, primarily hyperkalemia, that can occur in conditions like Diabetic Ketoacidosis (DKA).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain ECG interpretation in electrolyte imbalances as background academic context rather than a clinical decision trigger.
The ECG changes of hyperkalemia represent a medical emergency due to the high risk of progressing to fatal arrhythmias like ventricular fibrillation or asystole.
A nurse identifying these changes on an ECG must immediately notify the healthcare provider, ensure the patient is on a continuous cardiac monitor, and anticipate orders for emergency treatment.
Emergency interventions include administering IV calcium gluconate to stabilize the cardiac membrane, IV insulin with dextrose to shift potassium into the cells, and potentially sodium polystyrene sulfonate (Kayexalate) or dialysis to remove potassium from the body.

How to Approach the Question

First, identify the key clinical findings in the question: 'Tall-tented T waves' and 'widened QRS'.
Recognize that these are specific, classic patterns seen on an electrocardiogram (ECG).
Access your knowledge of how electrolyte imbalances affect the heart's electrical conduction system.
Correlate the specific pattern (peaked T waves and wide QRS) with its most common cause, which is hyperkalemia.
Briefly consider the other options to confirm they do not cause this specific combination of ECG changes, thus solidifying your choice.

Concept Tested & Keywords

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E6 Medicine Harrison 22e Part 1 p. 1915-1917

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