Analyze the following electrocardiogram traces taken from the patient. البالسياسات التالية Trace 1. Taken during one of the episodes of supraventricular tachycardia سلسلي السلسل II Trace 2. Taken after the end of an episode of supraventricular tachycardia. It is observed in sinus rhythm Which of the following elements of the electrocardiogram tracing is absent during the tachycardia episode and reappears in the sinus rhythm tracing? a) ST segment b) P wave c) QRS complex d) T wave Briefly explain the origin of the electrical activity of the heart that is reflected in the P wave of the electrocardiogram.
The rhythmic contraction and relaxation of heart muscles is what we call the heart beat. A healthy human heart beats 72 times per minute. The ability of the heart to contract spontaneously at a regular rate is called the automatic rhythmicity of the heart.
A cardiac cycle is initiated by the spontaneous generation of an action potential in the SA (Sinoatrial) node. This action potential travels through the atria, making the atria contract. This pumps the blood from the atria into the ventricles. The cardiac impulse emitted by the SA node then reaches the AV (atrioventricular) node and stimulates the AV node to emit an impulse which causes the ventricular muscles to contract. Contraction of the ventricles generates the pressure required to pump the blood from the ventricles to different parts of the body.
ECG is a graphic record of the electric current generated by the excitation of heart muscles. A normal ECG has a characteristic structure as shown below.
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