ECG Changes in Hypokalemia
ECG Changes in Hypokalemia
ECG changes in Hypokalemia :
1.prolongs ventricular diastole
2.Flattening of T wave
3.ST segment depression
4.prolongation of QT interval
5.The appearance of U wave
6.Pseudo P pulmonale
2.Flattening of T wave
3.ST segment depression
4.prolongation of QT interval
5.The appearance of U wave
6.Pseudo P pulmonale
1. What is the hallmark ECG change in hypokalemia?
In hypokalemia, the T waves become flat or inverted due to delayed ventricular repolarization.
2. Which additional ECG wave is most prominent in hypokalemia?
Prominent U waves are characteristic of hypokalemia and appear after the T wave.
3. How does hypokalemia affect the QT interval?
QT interval prolongation occurs due to delayed repolarization in hypokalemia.
4. Which arrhythmia is more likely in severe hypokalemia?
Severe hypokalemia predisposes to ventricular tachyarrhythmias, which can be life-threatening.
5. Hypokalemia increases the risk of toxicity from which drug?
Low potassium levels enhance digoxin binding to Na+/K+ ATPase, increasing toxicity risk.
6. What is the earliest ECG change seen in mild hypokalemia?
Flattening of T waves is often the first detectable ECG change in mild hypokalemia.
7. How does hypokalemia affect the ST segment?
ST segment depression is common in hypokalemia due to delayed ventricular repolarization.
8. Which electrolyte disturbance can mimic digitalis effect on ECG?
Both hypokalemia and digoxin cause ST segment scooping and flattened T waves.
9. What happens to P wave amplitude in hypokalemia?
Hypokalemia may cause increased P wave amplitude due to atrial depolarization changes.
10. How does hypokalemia affect PR interval?
PR interval prolongation occurs due to slowed conduction through the AV node in hypokalemia.
11. Which part of the cardiac cycle is prolonged in hypokalemia?
Repolarization is delayed in hypokalemia, leading to prolonged QT and prominent U waves.
12. Prominent U waves are best seen in which ECG leads?
U waves are most visible in the precordial leads, especially V2–V4.
13. Which change differentiates hypokalemia from hyperkalemia on ECG?
Prominent U waves are typical of hypokalemia, while peaked T waves occur in hyperkalemia.
14. Which ECG change in hypokalemia increases torsades de pointes risk?
Prolonged QT interval in hypokalemia increases susceptibility to torsades de pointes.
15. Which conduction abnormality can hypokalemia cause?
Hypokalemia can cause AV conduction delays, including second-degree AV block.
16. Severe hypokalemia is defined as serum potassium below?
Severe hypokalemia is usually defined as potassium levels less than 2.5 mmol/L.
17. Which rhythm is common in profound hypokalemia?
Atrial fibrillation is often triggered in profound hypokalemia due to atrial irritability.
18. Hypokalemia can cause which feature in ventricular ectopy?
Ventricular ectopy becomes more frequent in hypokalemia due to increased myocardial excitability.
19. Which finding is NOT typical of hypokalemia?
Peaked T waves are seen in hyperkalemia, not hypokalemia.
20. In hypokalemia, the risk of which life-threatening arrhythmia is increased?
Ventricular fibrillation risk is increased in hypokalemia due to prolonged repolarization.
| No. | Fact |
|---|---|
| 1 | Hypokalemia = serum K⁺ <3.5 mmol/L |
| 2 | Mild ECG changes start at 3.0–3.5 mmol/L |
| 3 | T-wave flattening is earliest sign |
| 4 | U waves best seen in precordial leads |
| 5 | QT prolongation due to delayed repolarization |
| 6 | ST depression may be present |
| 7 | Severe hypokalemia may cause ventricular arrhythmias |
| 8 | Risk of torsades de pointes increases with prolonged QT |
| 9 | Sinus bradycardia may occur |
| 10 | Hypokalemia increases digoxin toxicity risk |
| 11 | Prominent U waves may mimic prolonged QT |
| 12 | Hypokalemia often coexists with hypomagnesemia |
| 13 | Can cause PVCs, VT, VF |
| 14 | Hypokalemia delays phase 3 repolarization |
| 15 | ECG changes are reversible with correction |
| 16 | IV potassium used in severe cases |
| 17 | Oral supplementation for mild cases |
| 18 | Rapid correction risks hyperkalemia |
| 19 | Always correct magnesium if low |
| 20 | Continuous ECG monitoring advised in severe cases |
| Question | Answer |
|---|---|
| Early ECG change in hypokalemia | Flattening of T waves |
| Classic hallmark finding | Prominent U waves |
| QT interval effect | Prolongation |
| Associated ST segment change | Depression |
| Common rhythm disturbance | Ventricular ectopy |
| Lead with most prominent U wave | V2–V4 |
| Severe hypokalemia effect | Torsades de pointes |
| Potassium threshold for changes | <3.0 mmol/L |
| Mechanism of ECG change | Delayed ventricular repolarization |
| Possible conduction defect | AV block |
Q1. Which ECG change is most characteristic of hypokalemia?
Prominent U waves
Peaked T waves
Short QT interval
ST elevation
Hypokalemia is classically associated with prominent U waves, especially in precordial leads.
Q2. Hypokalemia typically causes the T wave to become:
Tall and peaked
Flattened
Inverted in all leads
Unchanged
T wave flattening is common in hypokalemia before the appearance of U waves.
Q3. In hypokalemia, the ST segment may appear:
Elevated
Unaffected
Depressed
Prolonged
Hypokalemia can cause ST segment depression due to delayed ventricular repolarization.
Q4. Which interval is prolonged in hypokalemia?
PR interval
QT interval
QRS duration
RR interval
Hypokalemia prolongs the QT interval, mainly due to the prominent U wave merging with the T wave.
Q5. The merging of T and U waves in hypokalemia can be mistaken for:
Prolonged QT interval
Short QT interval
Delta wave
Osborn wave
When U waves merge with T waves, it can mimic a prolonged QT interval.
Q6. Which arrhythmia risk increases with severe hypokalemia?
Atrial fibrillation only
Ventricular tachyarrhythmias
Sinus bradycardia
Wenckebach block
Severe hypokalemia increases susceptibility to ventricular tachycardia and fibrillation.
Q7. Prominent U waves are best seen in which leads?
Lead I and aVL
Leads II and III
Precordial leads V2–V4
aVR only
U waves are most prominent in the mid-precordial leads V2–V4 in hypokalemia.
Q8. Severe hypokalemia may cause which conduction abnormality?
First-degree AV block
LBBB
Ventricular ectopy
Atrial standstill
Ventricular ectopy is a common manifestation in severe hypokalemia.
Q9. Hypokalemia can mimic which other ECG abnormality?
Pericarditis changes
Digitalis effect
Hyperacute T waves
Brugada pattern
The downsloping ST depression in hypokalemia can resemble the digitalis effect.
Q10. Which electrolyte imbalance often coexists with hypokalemia and can affect ECG changes?
Hypomagnesemia
Hypercalcemia
Hypernatremia
Hypochloremia
Hypomagnesemia often accompanies hypokalemia and can exacerbate arrhythmia risk.
Q1. Which ECG change is most characteristic of hypokalemia?
Prominent U waves
Tall peaked T waves
Short QT interval
J-point elevation
Hypokalemia typically produces prominent U waves, especially in precordial leads.
Q2. What happens to the T wave in hypokalemia?
It becomes tall and peaked
It becomes flattened or inverted
No change
It fuses with the U wave
T waves in hypokalemia are often flattened or inverted due to delayed repolarization.
Q3. Which leads best show U waves in hypokalemia?
Lead I and aVL
Inferior leads
Precordial leads V2–V4
Lead aVR
U waves are most prominent in mid-precordial leads such as V2–V4.
Q4. How does hypokalemia affect the PR interval?
It may prolong the PR interval
It shortens the PR interval
No effect
It causes complete AV block
PR interval may be prolonged due to delayed atrial and AV nodal conduction.
Q5. Which arrhythmia risk increases with severe hypokalemia?
Atrial flutter
Sinus bradycardia
Ventricular tachycardia
First-degree AV block only
Severe hypokalemia predisposes to ventricular arrhythmias, including VT and VF.
1. Which of the following is an early ECG change in hypokalemia?
Hypokalemia first causes T-wave flattening before progressing to U waves and ST depression.
2. Prominent U waves in ECG are most commonly associated with:
Prominent U waves are a hallmark of hypokalemia, usually best seen in V2–V4 leads.
3. Hypokalemia typically causes which QT interval change?
Hypokalemia prolongs repolarization, resulting in QT interval prolongation.
| No. | Key Point |
|---|---|
| 1 | Hypokalemia refers to serum potassium level below 3.5 mmol/L. |
| 2 | Most common ECG change is ST segment depression. |
| 3 | Flattening or inversion of T waves is a hallmark finding. |
| 4 | Appearance of prominent U waves is characteristic. |
| 5 | QT interval is often prolonged due to delayed repolarization. |
| 6 | PR interval may be prolonged in severe hypokalemia. |
| 7 | Ventricular ectopics are more common with low potassium levels. |
| 8 | Hypokalemia predisposes to atrial fibrillation. |
| 9 | Risk of ventricular tachycardia and fibrillation increases. |
| 10 | Severe hypokalemia may cause sine wave pattern if associated with other electrolyte disturbances. |
| 11 | ST depression and T wave flattening are best seen in precordial leads. |
| 12 | Digitalis toxicity risk is increased in hypokalemia. |
| 13 | Hypokalemia delays ventricular repolarization. |
| 14 | Combination of T wave inversion and U waves may mimic ischemia. |
| 15 | Amplitude of P waves may be increased. |
| 16 | Sinus bradycardia can occur in severe cases. |
| 17 | Hypokalemia should be corrected before anesthesia to reduce arrhythmia risk. |
| 18 | ECG changes may not appear until potassium is markedly low (<3.0 mmol/L). |
| 19 | Early detection via ECG can prevent fatal arrhythmias. |
| 20 | Potassium replacement must be done cautiously to avoid rebound hyperkalemia. |
