A typical heart beat on an electrocardiogram (ECG) consists of several components, including the P wave, the QRS complex, and the T wave.
The P wave represents the electrical activity of the atria, the upper chambers of the heart, as they contract and pump blood into the ventricles, the lower chambers of the heart. The P wave is typically small and smooth in shape.
The QRS complex represents the electrical activity of the ventricles as they contract and pump blood out of the heart. The QRS complex is typically larger and more complex in shape than the P wave.
The T wave represents the recovery period of the ventricles, when they are recharging for the next contraction. The T wave is typically smaller and smoother in shape than the QRS complex.
Together, these three components make up a single heart beat on an ECG.
P WAVE
A P wave on an electrocardiogram (ECG) is a small deflection that occurs at the beginning of the cardiac cycle, indicating the depolarisation of the atria, the upper chambers of the heart. The P wave is usually the first waveform that is seen on an ECG.
The P wave is usually positive in lead I and II, and it has a small amplitude, usually not exceeding 2.5 mm. It has a duration of 0.06-0.11 sec and its shape is usually smooth and rounded. The P wave is usually followed by the QRS complex, which represents the depolarization of the ventricles, the lower chambers of the heart.
The shape, duration, and amplitude of the P wave can provide important information about the health of the heart. For example, certain heart conditions, such as atrial fibrillation, can cause the P wave to be abnormal in shape or duration.
QRS Complex
The QRS complex on an electrocardiogram (ECG) represents the electrical activity of the ventricles, the lower chambers of the heart, as they contract and pump blood out of the heart. It is typically the most prominent part of the cardiac cycle on an ECG, and it is usually followed by the T wave.
The QRS complex is made up of three waves: the Q wave, the R wave, and the S wave. The Q wave is the initial downward deflection, the R wave is the initial upward deflection, and the S wave is the final downward deflection. The QRS complex typically has a duration of less than 0.12 seconds, which is considered normal.
The shape, duration, and amplitude of the QRS complex can provide important information about the health of the heart. For example, certain heart conditions, such as ventricular tachycardia or bundle branch block, can cause the QRS complex to be abnormal in shape or duration.
T Wave
The T wave on an electrocardiogram (ECG) represents the repolarization of the ventricles, the lower chambers of the heart, after they have contracted and pumped blood out of the heart. It typically follows the QRS complex and is usually the last waveform seen on an ECG.
The T wave is usually positive in lead I, II, and V3-V6. It has a small amplitude, usually not exceeding 5 mm in leads V2-V6, and a duration of 0.1-0.2 sec. The T wave’s shape is usually smooth and rounded, and it’s polarity is opposite to the QRS complex.
The shape, duration, and amplitude of the T wave can provide important information about the health of the heart. For example, certain heart conditions, such as myocardial infarction (heart attack) can cause the T wave to be abnormal in shape or amplitude.