0071643192.pdf

HYPOCALCEMIA

ECG FINDINGS(SEEFIGURE2.9)

■ Hallmark=QT prolongation

■ Due to lengthening of the ST segment

■ Occurs with Ca+<6.0 mg/dL

Digitalis Effect

This should be differentiated from digitalis toxicity.

ECG FINDINGS

■ Depressed (scooped or sagging) ST segments

■ Shortened QT intervals

■ Flattened T waves

■ Prominent U waves

Hypothermia

The heart becomes very irritable in the hypothermic (core temperature <35°C)

patient.

ECG FINDINGS(SEEFIGURE2.10)

■ Cardiac conduction abnormalities

■ Typical progression from sinus bradycardia to atrial fibrillation to ven-

tricular fibrillation

■ Osborn (or J) wavesat end of QRS complex

■ Characteristic but canbe seen in other heart conditions

See Table 2.1 for summary of ECG essentials.

CARDIOVASCULAR EMERGENCIES

Normal

QT 0.36 s

QTC0.41

QT 0.48 s

QTC0.52

QT 0.26 s

QTC0.36

Hypocalcemia Hypercalcemia

I

II

I

II

FIGURE 2.9. ECG findings in hypercalcemia and hypocalcemia.

(Reproduced, with permission, from Kasper DL, Braunwald E, Fauci AS, et al. Harrison’s Principles

of Internal Medicine, 16th ed. New York: McGraw-Hill, 2005:1319.)