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Sinus tachycardia is a sinus rhythm of the heart, with an increased rate of electrical discharge from the sinoatrial node, resulting in a tachycardia, a heart rate that is higher than the upper limit of normal (90-100 beats per minute for adult humans). [1] The normal resting heart rate is 60–90 bpm in an average adult. [2]
Sinus node dysfunction also known as sick sinus syndrome is a group of irregular heartbeat conditions caused by faulty electrical signals of the heart. When the heart's sinoatrial node is defective, the heart's rhythms become abnormal—typically too slow or exhibiting pauses in its function or a combination, and very rarely faster than normal.
Sinus bradycardia is a sinus rhythm with a reduced rate of electrical discharge from the sinoatrial node, resulting in a bradycardia, a heart rate that is lower than the normal range (60–100 beats per minute for adult humans). [1] [2]
Normal heart rate (classically 60 to 100 beats per minute for an adult). Regular rhythm, with less than 0.16-second variation in the shortest and longest durations between successive P waves The sinus node should pace the heart – therefore, P waves must be round, all the same shape, and present before every QRS complex in a ratio of 1:1.
It employs pacemaker cells that produce electrical impulses, known as cardiac action potentials, which control the rate of contraction of the cardiac muscle, that is, the heart rate. In most humans, these cells are concentrated in the sinoatrial (SA) node, the primary pacemaker, which regulates the heart’s sinus rhythm.
The oblique sinus is an inverted J-shaped reflection of the venae cavae and pulmonary veins. [2] It lies behind the atria (particularly the left atrium), [1] and in between left and right pulmonary veins. The transverse sinus is the tunnel-shaped passage posterior to the aorta and pulmonary trunk, and anterior to the superior vena cava.
A sinus infection typically starts out with a viral infection (RSV or rhinovirus, for example), which can cause sneezing, coughing, a runny nose, aches, and a fever, says Goudy.
The AV node lies at the lower back section of the interatrial septum near the opening of the coronary sinus, which conducts the normal electrical impulse from the atria to the ventricles. The AV node is quite compact (~1 x 3 x 5 mm). [ 2 ]