The key difference between PAC and sinus arrhythmia is that PAC is extra heartbeats that begin in one of the heart’s two upper chambers called atria, while sinus arrhythmia is an irregularity in the heart rhythm that begins at the sinus node of the right atrium.
An arrhythmia is a condition where the heart rhythm is abnormal. Arrhythmia can start in different parts of the heart and results in too fast, too slow, or irregular heartbeats. There are different types of arrhythmias; PAC and sinus arrhythmia are two such types.
CONTENTS
1. Overview and Key Difference
2. What is PAC
3. What is Sinus Arrhythmia
4. Similarities – PAC and Sinus Arrhythmia
5. PAC vs. Sinus Arrhythmia in Tabular Form
6. Summary – PAC vs. Sinus Arrhythmia
What is PAC?
Premature atrial contraction (PAC) starts in the upper chambers of the heart and gives people a feeling of an extra or skipped heartbeat. This condition can be caused by a drop in the amount of blood going into the heart, injury to the heart, hypertrophic cardiomyopathy, and a problem with the amount of electrolytes or minerals. The risk factors for PAC include age (older adults), height (taller people are affected more), cardiovascular disease, less exercise, high HDL cholesterol, higher systolic blood pressure, drinking less water, taking in excessive caffeine or stimulants, not having adequate restful sleep, high levels of stress, and electrolyte abnormalities. The signs and symptoms of PAC may include heartbeats that have a lot of force, heartbeats that skip, palpitations, and shortness of breath.
Figure 01: PAC
PAC can be diagnosed through physical examination, electrocardiogram, temporary heart monitor, and echocardiogram. Furthermore, treatment options for PAC may include medication such as beta blockers and catheter ablation.
What is Sinus Arrhythmia?
Sinus arrhythmia is an irregularity in heart rhythm that originates at the sinus node of the right atrium. It typically manifests as either a faster heart rate (beating more than 100 beats per minute) or a slower heart rate (beating less than 60 bpm). There are three types of sinus arrhythmias such as respiratory sinus arrhythmia, nonrespiratory sinus arrhythmia, and ventriculophasic sinus arrhythmia. Among them, respiratory sinus arrhythmia is usually a normal condition. Sinus arrhythmia is caused by stimulation of the vagus nerve and changes in cardiac filling pressures during respiration, having had a head or neck injury, taking too much digoxin, having heart disease, and having third-degree AV block. The risk factors for sinus arrhythmia include age (young people are affected more), certain medical conditions such as heart disease, hypothyroidism, hyperthyroidism, high blood pressure, alcohol consumption, tobacco use, excessive exercise, caffeine consumption, certain medications and recreational drugs, over-weight, and viral illness. Moreover, the symptoms of sinus arrhythmia may include feeling a slight change in the pulse rate as people breathe in and exhale, chest discomfort, palpitations, pounding heartbeats, dizziness, fatigue, difficulty breathing, and syncope.
Figure 02: Sinus Arrhythmia
Sinus arrhythmia can be diagnosed through electrocardiogram, ambulatory monitors, stress test, echocardiogram, ultrasound, electrophysiology study (EPS), cardiac catheterization, and tilt table test (head-up tilt test). Furthermore, treatment options for sinus arrhythmia may include medications such as beta-blockers or calcium channel blockers and certain lifestyle changes such as regular exercise, maintaining a healthy weight, reducing stress, and avoiding caffeine and alcohol.
What are the Similarities Between PAC and Sinus Arrhythmia?
- PAC and sinus arrhythmia are two different types of cardiac arrhythmias.
- Both types can start from atria.
- They may produce similar symptoms, such as fatigue, difficulty in breathing, etc.
- Both types can be diagnosed through physical examination, electrocardiogram, and echocardiogram.
- They can be treated through medications such as beta blockers.
What is the Difference Between PAC and Sinus Arrhythmia?
PAC refers to extra heartbeats that begin in the atria, while sinus arrhythmia is an irregularity in the heart rhythm that begins at the sinus node of the right atrium and generally results in a faster heart rate or slower heart rate. Thus, this is the key difference between PAC and sinus arrhythmia. Furthermore, PAC can be caused by a drop in the amount of blood going into the heart, injury to the heart, hypertrophic cardiomyopathy, and a problem with the amount of electrolytes or minerals. On the other hand, sinus arrhythmia can be caused by stimulation of the vagus nerve and changes in cardiac filling pressures during respiration, having had a head or neck injury, taking too much digoxin, having heart disease, and having third-degree AV block.
The infographic below presents the differences between PAC and sinus arrhythmia in tabular form for side-by-side comparison.
Summary – PAC vs. Sinus Arrhythmia
Arrhythmia is a condition in which the heart beats with an irregular rhythm. Some of them are atrial fibrillation, ventricular tachycardia, atrial flutter, supraventricular tachycardia, ventricular fibrillation, premature ventricular contraction (PAC), and sinus arrhythmia. PAC is a type of cardiac arrhythmia that starts in the upper chambers of the heart and gives people a feeling of an extra or skipped heartbeat, while sinus arrhythmia is a type of cardiac arrhythmia that starts at the sinus node of the right atrium, which generally manifests as a faster heart rate (beating faster than 100 beats per minute (bpm) or a slower heart rate (beating slower than 60 bpm). So, this summarizes what is the difference between PAC and sinus arrhythmia.
Reference:
1. “Premature Atrial Contractions: Causes, Symptoms, Diagnosis, Treatment.” WebMD.
2. “Sinus Arrhythmia: Causes, Symptoms and Treatment.” Cleveland Clinic.
Image Courtesy:
1. “NSR and Ectopic beats (PVC and PAC)” By YitzhakNat – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “ECG Sinus Arrhythmia 79 bpm” By Ewingdo – Own work (CC BY-SA 4.0) via Commons Wikimedia