16/12/2008 ECG Diag 8/Ghazi

Principles of ECG Diagnosis 8

Electrolytes, Drugs & miscellaneous conditions

Dr Ghazi Ahmad RadaidehMD, FRCP

Rashid HospitalDubai - UAE

16/12/2008 ECG Diag 8/Ghazi

Reading 12-Lead ECG step-by-step (RAWIHI)

1. Rate, Rhythm and Regularity2. Determine the QRS Axis3. Evaluate the Waves (P,QRS,T ),

Intervals (PR,ST,QT)4. Evaluate for chamber Hypertrophy5. Look for myocardial Infarction and Ischemia6. Interpret the ECG

16/12/2008 ECG Diag 8/Ghazi

Objectives Hyperkalemia Hypokalemia Hypercalcemia Hypocalcemia Drugs Hypothermia Thyroid disease

16/12/2008 ECG Diag 8/Ghazi

ECG features of hyperkalaemia1.Normal

2. peaking of the T wave (K+ about 6-7 mEq/L)

3. T wave becomes taller and more peaked

(K+ about 7-8 mEq/L);

4.P wave decreases, the PR lengthens, QRS widens (K+ >8 mEq/L).

5. P waves disappear , QRS becomes sinusoid (K+ >10 mEq/L).

V Fib usually follows

1

2

3

4

5

16/12/2008 ECG Diag 8/Ghazi

8.1HyperkalemiaHyperkalemia

16/12/2008 ECG Diag 8/Ghazi

ECG features of Hypokalemia1. Normal2. flattening of the T wave3/4. A "U wave" then

develops

5/6. ST depression is more noticeable and the U wave increases in amplitude until ultimately the U wave overtakes the T wave(? QT interval prolongation)

16/12/2008 ECG Diag 8/Ghazi

ECG features of Hypercalcaemia_ Slight increase in QRS duration._ ST segment short or absent._ PR interval may be prolonged._ Short Q-T interval. abnormal Q;

16/12/2008 ECG Diag 8/Ghazi

ECG features of HypocalcaemiaSlight decrease in QRS duration.ST segment lengthened and corrected QT interval prolonged.PR interval may be shortened.T waves become flat or inverted in severe hypocalcemia

Hypocalcemia leads to increase cardiac contractility and arrhythmias..

16/12/2008 ECG Diag 8/Ghazi

Hypocalcaemia

16/12/2008 ECG Diag 8/Ghazi

Hypo and Hypermagnesemia It is uncertain if changes in body

magnesium alone affect the surface ECG. Hypomagnesemia is usually associated

with K+ depletion and the ECG demonstrates the characteristic changes of hypokalemia. Ventricular arrhythmias may be present.

16/12/2008 ECG Diag 8/Ghazi

Effect of drugs

16/12/2008 ECG Diag 8/Ghazi

Digitalis Effect S-T segment depression and sagging ( especially in lead V4). Low amplitude T wave. Shortened Q-T interval. Shortened P-R interval

16/12/2008 ECG Diag 8/Ghazi

Digitalis effect

LVH effect

Digoxin effect

ST sagging and J point depression

ST depression and T inversion

Normal

Normal

16/12/2008 ECG Diag 8/Ghazi

Digitalis toxicity Bradycardia when previously normal or fast

(due to SA or AV block). Tachycardia when previously normal

(due to AT,JT, or fascicular VT). Unexpected regularity

(due to CHB with a regular AV junctional rhythm in a patient with prior AF or AFL).

Regular irregularity (due to group beating of ventricular Bigeminy, SA, or

Wenckebach, or a combination of these).

16/12/2008 ECG Diag 8/Ghazi

Quinidine Effect & Other Class IA Antiarrhythmics)

Prolonged Q-Tinterval.

Slightly widened QRScomplex. Less common U waves and flattened or inverted T waves

16/12/2008 ECG Diag 8/Ghazi

Phenothiazines effect

Mimics hypokalemia. Prominent U waves. Low amplitude T waves or T wave inversion.

ST segment depression. Prolonged QT interval.

ECG changes seen in approximately 50% of patients receiving "therapeutic" doses.

16/12/2008 ECG Diag 8/Ghazi

Hypothermia

16/12/2008 ECG Diag 8/Ghazi

ECG features of hypothermia Tremor artifact from shivering AF with slow ventricular rate J waves (Osborne waves) Bradycardias, especially junctional Prolongation of PR, QRS, and QT intervals PVC, VT, VF Asystole

Hypothermia is present when the core temperature is less than 35C.

16/12/2008 ECG Diag 8/Ghazi

Hypothermia: J-waves or Osborne Waves

16/12/2008 ECG Diag 8/Ghazi