Questions should involve any history of cardiac disease both current and congenital, recent cardiac procedures and current medications. 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. Patients who have severe bradycardia resulting in hypotension and decreased cardiac output may be diaphoretic and pale. Patients who have a second-degree atrioventricular block secondary to myocardial ischemia may present with chest pain.

ECG is used to determine if a second-degree AV block is present. If ischemia is suspected based on the clinical picture and/or ECG findings, then cardiac biomarkers and chest radiography may be indicated. Serum electrolytes, calcium, and magnesium should be checked. If a patient is on digoxin, a level should be obtained to evaluate for toxicity. Routine imaging is not required for initial evaluation of second-degree atrioventricular block.[6][7][8][9]

Electrophysiologic testing is sometimes done to determine the level of the block and the need for a pacemaker.

Treatment for a Mobitz type I (Wenckebach) is often not necessary. Occasionally type I blocks may result in bradycardia leading to hypotension. If hypotension and bradycardia occur, type I blocks respond well to atropine. If unresponsive to atropine, pacing (transcutaneous or transvenous) should be initiated for stabilization. 

If the patient is on any beta blockers, calcium channel blockers or digoxin, the dose of these medications should be reduced or the medication discontinued. All patients with Mobitz 1 block should be admitted and monitored.

Treatment for a Mobitz type II involves initiating pacing as soon as this rhythm is identified. Type II blocks imply structural damage to the AV conduction system. This rhythm often deteriorates into complete heart block. These patients require transvenous pacing until a permanent pacemaker is placed. Unlike Mobitz type I (Wenckebach), patients that are bradycardic and hypotensive with a Mobitz type II rhythm often do not respond to atropine.

Differential diagnosis includes congenital heart block, sinoatrial exit block, non-conducted premature atrial complexes, first-degree atrioventricular block, myocardial infarction, medication toxicity, and third-degree atrioventricular block.

The prognosis for Mobitz type I (Wenckebach) is excellent. This is usually asymptomatic and requires no intervention in asymptomatic patients.

The prognosis for Mobitz type II varies based on the cause of the rhythm. Patients require placement of implanted pacemaker devices to avoid complications of Mobitz type II AV blocks such as decreased cardiac output, symptomatic bradycardia, and sudden cardiac arrest.

• Complete heart block
• Syncope
• Dizziness
• Chest pain
• Death

All patients with AV block need lifelong follow up.

Once an AV block has been identified, the cardiologist should be consulted for management.

It can often be challenging to separate the two types of second-degree AV blocks. A rhyme is often used to remember type I or Wenckebach: “longer, longer, longer, DROP, now you have a Wenckebach.” This rhyme is alluding to the progressive prolongation of the PR interval before a non-conducted beat or the lack of a QRS complex after a P wave.

When a Mobitz type I has a fixed conduction ratio of 2:1, meaning 2 conducted beats to one non-conducted beat, it is difficult to differentiate between type I and type II. In this scenario, it is recommended to assume the worst-case scenario and call this rhythm a “non-typeable second-degree AV block.” This should be managed like a type II with transcutaneous or transvenous pacing until further workup can be completed.

The diagnosis and management of second-degree heart block is made by an interprofessional team that includes a cardiologist, ICU nurse, and an internist. When patients are diagnosed with a heart block, an appropriate referral to a cardiologist is highly recommended. [10]

In the emergency room type 1 Mobitz block without symptoms requires no treatment. However, symptomatic patients may be managed with atropine or transvenous pacing and a cardiology consult should be obtained. The patient must be admitted to a monitored unit.

All patients with type ll Mobitz block need admission and treatment. Nurses should be aware of this type of block and its treatment. Hypotension and bradycardia are often resistant to atropine and transvenous pacing can be life-saving. The pharmacist should ensure that the patient is on no medication that can aggravate or trigger the heart block. In addition, the patient must be educated on both types 1 and 2 heart block and their management. Close communication between the team members is vital to prevent mortality.

The prognosis for Mobitz type I (Wenckebach) is excellent. This is usually asymptomatic and requires no intervention in asymptomatic patients.

The prognosis for Mobitz type II varies based on the cause of the rhythm. Patients require placement of implanted pacemaker devices to avoid complications of Mobitz type II AV blocks such as decreased cardiac output, symptomatic bradycardia, and sudden cardiac arrest.