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 2nd Degree Heart Block on ECG
Introduction
Second-degree heart block is a type of atrioventricular (AV) block where electrical signals between the atria and ventricles are impaired. Recognizing this condition on an electrocardiogram (ECG) is crucial for proper diagnosis and management.
Types of 2nd Degree Heart Block
There are two types:
Mobitz Type I (Wenckebach)
- Progressive prolongation of the PR interval until a QRS complex is dropped.
- Usually benign and often does not require treatment.
Mobitz Type II
- The PR interval is constant, but intermittently, a QRS complex is missing.
- More dangerous because it can progress to complete heart block.
ECG Findings
- Mobitz I: Gradually increasing PR interval followed by a dropped beat.
- Mobitz II: Sudden loss of QRS complexes without PR lengthening.
- Atrial rate > Ventricular rate: Indicates block in conduction.
Causes & Risk Factors
- Aging and degeneration of the conduction system
- Myocardial infarction (especially if it affects the AV node)
- Electrolyte imbalances (e.g., hyperkalemia)
- Medications (e.g., beta-blockers, calcium channel blockers, digoxin)
Treatment & Management
- Mobitz Type I:
- Usually no treatment if asymptomatic.
- Monitoring for progression.
- Adjusting medications if needed.
- Mobitz Type II:
- Often requires a pacemaker.
- Medication adjustments and monitoring for complete heart block.
Conclusion
Identifying 2nd-degree heart block on an ECG is essential because Mobitz II can lead to serious complications. If you experience symptoms like dizziness or fainting, medical evaluation is necessary.
Source recommendations
1. American Heart Association Guidelines on Heart Block
- https://www.heart.org/en/health-topics/arrhythmia/about-arrhythmia/conduction-disorders
- https://www.ahajournals.org/doi/10.1161/CIR.0000000000000628
- https://cpr.heart.org/en/resuscitation-science/cpr-and-ecc-guidelines/algorithms
- https://professional.heart.org/en/guidelines-and-statements
- https://cpr.heart.org/-/media/cpr-files/cpr-guidelines-files/algorithms/algorithmacls_bradycardia_200612.pdf
2. European Society of Cardiology Guidelines on Cardiac Arrhythmias
- https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Ventricular-Arrhythmias-and-the-Prevention-of-Sudden-Cardiac-Death
- https://academic.oup.com/eurheartj/article/43/40/3997/6675633
- https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Supraventricular-Tachycardia
- https://pubmed.ncbi.nlm.nih.gov/36017572/
- https://www.ahajournals.org/doi/10.1161/01.cir.0000091380.04100.84
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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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