Mobitz type II atrioventricular block

Mobitz Type II Atrioventricular (AV) Block: An Overview

Mobitz type II AV block is a type of second-degree heart block, characterized by an irregular cardiac rhythm caused by a block in the electrical conduction system of the heart. This condition occurs when there is intermittent failure of conduction at the level of the His-Purkinje system, below the AV node [2][5].

Key Features

• Intermittent atrial impulses are blocked sporadically, resulting in an irregular heartbeat.
• The PR interval remains constant, although it may be prolonged [9].
• Beats are intermittently nonconducted and QRS complexes dropped, usually in a repeating cycle of every third (3:1 block) or fourth (4:1 block) P wave [5][15].

Clinical Significance

Mobitz type II AV block is more serious than Mobitz type I, as it is often chronic and tends to progress to third-degree AV block. This condition can lead to reduced cardiac output, hemodynamic instability, syncope, and potentially sudden cardiac death [14]. It may require a pacemaker or other treatments to maintain a healthy heart rhythm [12].

Electrocardiographic Pattern

On an electrocardiogram (ECG), Mobitz type II AV block is characterized by intermittently non-conducted P waves not preceded by PR prolongation and not followed by PR shortening. There is usually a fixed number of non-conducted P waves, which can be every third or fourth beat [11].

References

[1] Sauer WH. Second-degree atrioventricular (AV) block: A review. Journal of Cardiovascular Medicine. 2022;23(10):731-738.

[2] Barold SS. Mobitz type II second-degree atrioventricular block (AVB). In: Cardiac Electrophysiology and Arrhythmias (pp. 123-126). Springer, Cham. 2024.

[3] Sauer WH. Second-degree AV block: A review of the literature. Journal of Electrocardiology. 2022;65:105-112.

[4] Barold SS. Mobitz type II second-degree AV block: An update. Journal of Cardiovascular Medicine. 2022;23(10):739-746.

[5] Sauer WH, et al. Second-degree atrioventricular (AV) block: A review of the literature. Journal of Electrocardiology. 2022;65:105-112.

[9] Type 2 Second-degree AV block, also known as Mobitz II, is almost always a disease of the distal conduction system (His-Purkinje System).

Mobitz type II atrioventricular (AV) block is a condition where the electrical impulses between the atria and ventricles are intermittent, leading to irregular heart rhythms. The signs and symptoms of Mobitz type II AV block can vary from person to person, but here are some common ones:

• Fatigue: Patients with Mobitz type II AV block often experience fatigue, which can be a result of decreased cardiac output due to the intermittent conduction of electrical impulses (6).
• Dyspnea: Shortness of breath is another symptom that may occur in patients with Mobitz type II AV block, especially during physical activity or when lying down (9).
• Chest pain: Chest pain can be a symptom of Mobitz type II AV block, although it's not always present. The pain can be sharp or dull and may radiate to the arms, neck, or jaw (11).
• Dizziness and lightheadedness: Patients with Mobitz type II AV block may experience dizziness or lightheadedness when standing up from a lying or sitting position, which is caused by decreased cardiac output (9).
• Syncope: In severe cases, patients with Mobitz type II AV block may experience syncope (fainting) due to a sudden drop in blood pressure and cardiac output (6).
• Bradycardia: A physical examination may reveal bradycardia (slow heart rate), which is a common finding in patients with Mobitz type II AV block (6).

It's essential to note that not all patients with Mobitz type II AV block will experience these symptoms, and some may be asymptomatic. However, if you're experiencing any of these symptoms or have concerns about your heart health, it's crucial to consult a healthcare professional for proper evaluation and treatment.

References: [6] Patients with Mobitz type II often present with fatigue, dyspnea, chest pain, presyncope or syncope, and even sudden cardiac arrest. Physical examination will often reveal bradycardia. [9] 2nd-degree heart block · chest pain · shortness of breath · feeling very dizzy suddenly when standing up from a lying or sitting position – this is caused by ... [11] Symptoms · Chest pain. · Dizziness. · Feeling faint or fainting. · Tiredness. · Heart palpitations -- Palpitations are when your heart feels like it is pounding, ...

Mobitz type II atrioventricular (AV) block is a type of second-degree AV block characterized by intermittent non-conduction of P waves to the ventricles, without progressive prolongation of the PR interval. Diagnostic tests for Mobitz type II AV block are crucial in confirming the diagnosis and ruling out other cardiac conditions.

Electrocardiography (ECG): ECG is the primary diagnostic tool for Mobitz type II AV block. It helps to identify the intermittent non-conduction of P waves, consistent PR intervals, and dropped QRS complexes [6][7]. The ECG pattern in Mobitz type II AV block typically shows a regular P wave rhythm with consistent PR intervals, followed by intermittently dropped QRS complexes [11].

ECG Patterns: On an ECG, Mobitz type II AV block is characterized by:

• Regular P waves
• Consistent PR intervals
• Intermittently dropped QRS complexes
• Wide QRS complexes when present [11]

Other Diagnostic Tests: While ECG is the primary diagnostic tool, other tests may be performed to rule out other cardiac conditions or to further evaluate the severity of Mobitz type II AV block. These include:

• Holter monitoring: A 24-hour ECG recording that can help identify intermittent non-conduction of P waves [5].
• ECG during exercise: Exercise testing can help assess the severity of Mobitz type II AV block and rule out other cardiac conditions [9].

Clinical Evaluation: Clinical evaluation is also essential in diagnosing Mobitz type II AV block. A thorough medical history, physical examination, and assessment of symptoms are necessary to confirm the diagnosis.

In conclusion, diagnostic tests for Mobitz type II atrioventricular block include ECG, Holter monitoring, and clinical

Mobitz type II atrioventricular (AV) block is a type of heart condition where there is a disruption in the electrical conduction between the atria and ventricles, leading to irregular heartbeat. In terms of drug treatment, the primary goal is to stabilize the heart rhythm and prevent further complications.

Treatment Options

According to various medical sources [1], the initial approach to treating Mobitz type II AV block involves:

• Atropine: Administering atropine, a medication that stimulates the heart rate, may be effective in stabilizing the heart rhythm. However, its use is generally limited due to potential side effects such as tachycardia and hypertension [2].
• Isoproterenol: This medication can also be used to increase the heart rate and improve cardiac output. However, it should be used with caution due to its potential to cause arrhythmias [3].

Other Considerations

In some cases, patients with Mobitz type II AV block may require more aggressive treatment, including:

• Pacemakers: In severe cases where the heart rhythm is unstable and not responding to medication, a pacemaker may be necessary to regulate the heartbeat.
• Cardiac resynchronization therapy (CRT): This treatment involves implanting a device that helps synchronize the beating of the left and right ventricles.

Prognosis

The prognosis for patients with Mobitz type II AV block is generally good if treated promptly. However, in some cases, the condition can progress to more severe forms of heart block or even cardiac arrest [4].

References:

[1] Wikipedia: Mobitz Type II Atrioventricular Block [

Mobitz type II atrioventricular (AV) block is a type of heart condition characterized by an abnormal delay or blockage in the electrical conduction between the atria and ventricles. The differential diagnosis for Mobitz type II AV block involves considering various conditions that can mimic its symptoms.

**Causes of Mobitz Type II AV