effect of electrolytes on cardiac rhythm
TRANSCRIPT
EFFECT OF ELECTROLYTES ON CARDIAC RHYTHM
Prepared by: Ahmad Thanin
OBJECTIVES:By the end of session learners will be able to:
• Define Electrolytes.• Discuss the function of electrolytes• Describe the relationship of electrolyte with
heart• List down common electrolytes
responsible for cardiac function• Explain the effect of electrolytes on heart• Interpret the ECG features of different
electrolyte imbalances• Summarize the main key points of the
session
What are Electrolytes?
Chemically, electrolytes are substances that become ions in solution and acquire the capacity to conduct electricity. Electrolytes are present in the human body, and the balance of the electrolytes in our bodies is essential for normal function of our cells and our organs.
FUNCTIONS:
Electrolytes and Heart:
• The normal state of cardiac cell membrane polarization is dependent upon the maintenance of a normal ionic balance across the membranes
Common Electrolytes responsible for cardiac arrhythmias
• Potassium• Magnesium• Calcium
HYPERKALEMIA
Background•Potassium is vital for regulating the normal electrical activity of the heart.•Increased extracellular potassium reduces myocardial excitability, with depression of both pacemaking and conducting tissues.•Progressively worsening hyperkalemia leads to suppression of impulse generation by the SA node and reduced conduction by the AV node and His-Purkinje system, resulting in bradycardia and conduction blocks and ultimately cardiac arrest.
ECG features of Hyperkalemia:
• Rhythm: Atrial and ventricular rhythms are regular• Rate: Atrial and ventricular rates are within normal limits• P Wave: Mild-low amplitude, moderate-wide flattened,
severe-indiscernible• PR interval: Normal or prolonged; unmeasureable if P
wave cant be detected• QRS complex: Widened because ventricular
depolarization takes longer• QT interval: Shortened • ST segment: May be elevated in severe hyperkalemia • T wave: Tall, Peaked.
Peaked T waves in Hyperkalemia
Prolonged PR segment in Hyperkalemia
Broad P waves and QRS complexes
Loss of P waves
Bradycardia
HYPOKALEMIA
Background•Potassium is vital for regulating the normal electrical activity of the heart•Decreased extracellular potassium causes myocardial hyper excitability with the potential to develop re-entrant arrhythmias
ECG features of Hypokalemia:
• Rhythm: : Atrial and ventricular rhythms are regular• Rate: Atrial and ventricular rates are within normal limits• P Wave: Usually normal size and configuration • PR interval: May be prolonged • QRS complex: Within normal limits or possibly widened;
prolonged in hypokalemia• QT interval: Usually indiscernible as T wave flattens • ST segment: Depressed• T wave: Amplitude is decreased. Inverted T wave U
wave may appear.
T inversion and prominent U wave in Hypokalemia
Long QT interval in Hypokalemia
HYPOCALCEMIA
Background•Calcium is important in cardiac function; it exerts a positive inotropic effect on heart •Decreased calcium levels may cause decreased myocardial contraction.
ECG features of Hypocalcaemia:
• Rhythm: Atrial and ventricular rhythms are regular• Rate: Atrial and ventricular rates are within normal limits• P Wave: Normal size and configuration• PR interval: Within normal limits• QRS complex: Within normal limits• QT interval: Prolonged• ST segment: Prolonged • T wave: Normal size and configuration, may be flattened
Prolong QT interval in Hypocalcaemia
HYPERCALCAEMIA
Background•Calcium is important in cardiac function; it exerts a positive inotropic effect on heart •Increased calcium levels may block the conduction pathways of electrical impulse.
ECG features of Hypercalcemia:
• Rhythm: Atrial and ventricular rhythms are regular• Rate: Atrial and ventricular rates are within normal limits,
bradycardia or heart block may occur• P Wave: Normal size and configuration • PR interval: May be prolonged.• QRS complex: Within normal limits, may be prolonged • QT interval: Prolonged• ST segment: Normal• T wave: Normal size and configuration; may be
depressed.
Shortened QT interval in Hypercalcemia
HYPOMAGMESAEMIA
Background•Magnesium is required to support the heart muscle’s normal contraction-relaxation actions. •Decreased magnesium levels may cause irregular contraction of ventricles leading to arrhythmias.
ECG features of Hypomagnesaemia:
• Rhythm: Irregular ventricular rhythm • Rate: Atrial and ventricular rates may be regular• P Wave: May be normal • PR interval: Normal • QRS complex: Normal• QT interval: Normal • ST segment: Depressed• T wave: Tall T waves
Tall T waves in Hypomagnesaemia
Torsades de pointes
Depressed ST segment in Hypomagnesaemia
HYPERMAGMESAEMIA
Background•Magnesium is required to support the heart muscle’s normal contraction-relaxation actions. •Increased magnesium levels may cause delayed conduction of electrical impulse.
ECG features of Hypermagnesemia
• Rhythm: Atrial or ventricular rhythm may be regular • Rate: Atrial and ventricular rates may be regular• P Wave: May be normal • PR interval: prolonged• QRS complex: Widened• QT interval: Normal• ST segment: Normal • T wave: Normal
Prolonged PR interval in Hypermagnesemia
Wide QRS complex in Hypermagnesemia
In a nut shell
Hypocalcaemia- Prolonged ST and QT intervals
Hyperkalemia- shortened ST segment- widened T wave
Hypokalemia- ST depression- shallow, flat, inverted T wave- Prominent U wave
Hyperkalemia- Tall, peaked T waves- Flat P waves- widened QRS complex- Prolonged PR interval
Hypomagnesaemia- Tall T waves- Depressed ST segment
Hypermagnesemia- Prolonged PR interval- widened QRS complexes
Treatment:• Hyperkalemia Cocktail• Hypokalemia Potassium replacement• Hypercalcemia Magnesium• Hypocalcemia Calcium replacement• Hypermagnesemia Calcium replacement• Hypomagnesaemia Mg replacement