Sinus rhythm ECG: normal rate, tachycardia, values at the limits of the norm

By Cristiano Antonino On Apr 5, 2023

“Sinus rhythm” typically appears on EKG reports. An example is “Tracing characterized by the presence of sinus rhythm”

This shouldn’t scare the patient at all, it’s actually a good sign. Let’s see why.

Sinus rhythm: what is it?

With “sinus rhythm” in medicine we refer to the physiological rhythm with which the heart muscle contracts.

The term “sinus” derives from the atrial sinus node, i.e. a part of the heart where the physiological pacemaker is located, that part which determines the origin of the cardiac impulse which – propagating along the heart – regulates the frequency and rhythm of the contractions of the atrium and cardiac ventricle.

The alteration of the sinus node is the cause of the onset of various types of cardiac arrhythmias, characterized by the disappearance of the sinus rhythm, clearly detectable with an electrocardiogram (ECG).

When is the rhythm non-sinus?

The rhythm is NOT sinus in some types of cardiac arrhythmia, for example in atrial fibrillation or ventricular fibrillation, conditions that can endanger the patient’s life either indirectly (for example, the increased blood coagulability in chronic atrial fibrillation exposes the patient to increased risk of embolism and therefore of myocardial infarction and cerebral stroke) than directly (cardiac arrest in ventricular fibrillation).

Sinus rhythm: when is it normal and when is it not?

A sinus rhythm is considered “normal” when it has a rate between 60 and 100 beats per minute.

Two types of frequency alterations are possible:

tachycardia: sinus rhythm with a frequency above 100 beats per minute;
bradycardia: sinus rhythm with a frequency below 60 beats per minute.

Obviously tachycardia and bradycardia are not alone indicators of disease.

For example, it is absolutely normal, even for a healthy subject, to have transient tachycardia when performing large typical efforts or when he has a sudden strong emotion.

Bradycardia can also be normal, for example during sleep or when we are extremely relaxed, for example during yoga, and it is also quite common in professional athletes.

In other cases, however, these heart rate alterations – especially if they are NOT transient – can be alarm bells of a pathology or can themselves cause a pathology, for example severe bradycardia may not allow the heart to pump adequate amounts of blood in circle.

Sinus tachycardia and pathologies

Sinus rhythm increases and becomes tachycardic as a result of various conditions and pathologies, such as:

shock,
myocardial ischemia,
severe anemia,
hypertension,
pulmonary embolism,
heart failure.

These pathologies are potentially serious and fatal, and require the use of specific pharmacological therapies.

Increased sinus rhythm can also be caused by:

some drugs,
alcohol,
cigarette smoke,
abuse of coffee, tea and drinks containing caffeine,
some exciting food supplements (ginseng, ginko biloba, guarana…).

The symptoms that typically indicate sinus tachycardia are palpitations, sometimes associated with anxiety and shortness of breath, if associated with pain and without tightness in the chest, it is important to seek medical assistance as soon as possible.

To resolve a chronic tachycardia state, beta-blockers, antiarrhythmics and calcium channel blockers are used.