Electrocardiogram

ECG stands for electrocardiogram and is also known as EKG. ECG refers to the small voltages (~1mv) found on the skin caused by the sinus which is the heart's pacemaker. ECG electrodes usually come as 3,5 or 10 lead. These are:

3lead - Left ARM or LA, Right Arm or RA, and Left Leg or LL

5lead - additional leads of Right Leg or RL and V for Chest

10lead - additional leads of V1-V6 replacing the V lead, with each V lead being placed between the ribs

The health and function of the heart can be measured by the shape of the ECG waveform. Typical heart problems are leaking valves and blocked coronary arteries.

Electrolyte effects on the ECG

Calcium

Hypercalcemia

• Shortening of the QT interval

Hypocalcemia

• Prolongation of the QT interval

Potassium

Hyperkalemia

• Peaked T waves
• PR interval lengthens
• QRS duration increases

Hypokalemia

• Depression of the ST segment
• Decrease in the amplitude of the T wave
• U waves, especially in the lateral precordial leads V4-V6