About-Cardio
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We provide our users the most up-to-date and accurate information on the treatment and prevention of cardio pathologies in accordance with current American and European clinical guidelines.
The information provided on this website is for educational purposes only and should not be considered medical advice. Always consult a licensed physician for diagnosis and treatment.
Understanding 1st Degree Heart Block on ECG
Introduction
First-degree heart block is a mild form of atrioventricular (AV) block, meaning there is a delay in the transmission of electrical impulses from the atria to the ventricles. It is often detected on an electrocardiogram (ECG) and may be incidental or associated with underlying conditions.
ECG Characteristics
- PR Interval: The defining feature of 1st-degree AV block is a prolonged PR interval greater than 200 milliseconds (one large square on an ECG at normal paper speeds).
- Regularity: Despite the delay, every atrial impulse is still conducted to the ventricles, meaning there is no missed beat.
- No dropped beats: There is no progression to further heart block (such as 2nd or 3rd-degree AV block).
Causes
- Increased vagal tone (e.g., in athletes)
- Electrolyte imbalances (e.g., hyperkalemia)
- Medications (e.g., beta-blockers, calcium channel blockers, digoxin)
- Ischemic heart disease
- Myocarditis or cardiomyopathy
Clinical Significance
- Often benign and asymptomatic.
- Rarely progresses to a more severe form of heart block unless there is an underlying disease.
Treatment and Management
- No specific treatment if asymptomatic.
- Address underlying causes (e.g., medication adjustment, treating ischemic heart disease).
- Monitor for potential progression in patients with structural heart disease.
Conclusion
First-degree heart block is a relatively benign ECG finding in most cases. However, in certain populations, it may require monitoring or intervention depending on associated conditions.
Source recommendations
1. 2023 AHA/ACC/HRS Guidelines for the Evaluation and Management of Bradycardia
- https://www.ahajournals.org/doi/10.1161/CIR.0000000000001193
- https://pubmed.ncbi.nlm.nih.gov/30412710/
- https://www.hrsonline.org/guidance/clinical-resources
- https://www.ahajournals.org/doi/10.1161/cir.0000000000000499
- https://www.heartrhythmjournal.com/article/S1547-5271(23)02026-X/fulltext
2. European Society of Cardiology (ESC) Guidelines on Cardiac Pacing and Resynchronization Therapy
- https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Cardiac-Pacing-and-Cardiac-Resynchronization-Therapy
- https://academic.oup.com/eurheartj/article/42/35/3427/6358547
- https://pubmed.ncbi.nlm.nih.gov/34455430/
- https://academic.oup.com/eurheartj/article/34/29/2281/401445
- https://pubmed.ncbi.nlm.nih.gov/23801827/
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If you or your loved ones experience any of these symptoms, you should consult a doctor in time. Remember that self-medication can be dangerous, and timely diagnosis will preserve the quality and life expectancy.
The heart is an organ that does not know how to "keep silent" if something goes wrong. Chest pain, shortness of breath, swelling, dizziness, and rhythm disturbances are the symptoms that require our attention. The best prevention of heart disease is careful attention to your health, regular checkups with a doctor, and a healthy lifestyle. Take care of your heart, and it will serve you for many years!
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