University:
West Coast University
Course:
NURS 110 | Introduction to Professional Nursing
Academic year:

2021
Views:

266

Pages:

1
Author:

Jameson Hunt

2nd Degree AV Block (Mobitz Type II) Rate: Atrial regular. Ventricular rate is typically ¼ to ½ the atrial rate (depending on the amount of blockage in conduction) Rhythm: Atrial regular (P-P is regular). Ventricular irregular P waves: Upright and normal. Some Ps are not followed by a QRS (more Ps than QRS) PR Interval: The PR interval for conducted beats will be constant across the strip QRS Width: VHFRQGVIRUFRQGXFWHGEHDWV QT:  .40 May be longer with slower heart rates. Source of pacer: SA Node Characteristics: Second degree AV blocN7\SH,,LVDOVRUHIHUUHGWRDV0RELW],,RQO\WZRQDPHVWKLVWLPHſ This form of conduction delay occurs below the level of the AV node, either at the bundle of His (uncommon) or the bundle branches (common). A hallmark of this type of second-degree AV block is that there is a pattern of conducted P waves (with a constant PR interval), followed by one or more non-conducted P waves. The PR interval does not lengthen before a dropped beat. Remember that the P waves that are successful in conducting through have a constant PR interval. Since the SA node is firing in a regular pattern, the P to P intervals again march through in a regular pattern (P-P is regular). Since not all P waves are conducted into the ventricles, the R to R intervals will be irregular and the ventricular response (HR) may be in the bradycardia range. When the block occurs at the bundle of His, the QRS may be narrow since ventricular conduction is not disturbed in beats that are not blocked. If the blockage occurs at the level of the bundle branches, conduction through the ventricles will be slower therefore creating a wider QRS complex (>.12 seconds). Mobitz II is associated with a poorer prognosis, and complete heart block may develop. Causes are usually associated with an acute myocardial infarction, severe coronary artery disease or other types of organic lesions in the conduction pathway. The patient’s response to the dysrhythmia is usually related to the ventricular rate. The QRS complex is typically abnormal (wider than .12 seconds) due to the bundle branch block. The block may be in a ratio of 2:1 (two P waves for every QRS), 4:3, 3:2. Causes: Can be caused by damage to the bundle branch system following an acute anterior AMI. This is not caused by medications or increased vagal tone Nursing Priorities: Check the patient’s blood pressure. Assess the patient’s symptoms. Note: Mobitz II has the potential to suddenly progress to complete heart block or ventricular standstill; have a temporary pacemaker nearby! Potential Treatment: Asymptomatic: Observation and monitoring only. Hold drugs that can slow AV node conduction. Notify physician. Obtain supplies for pacing should this become necessary. Symptomatic: If symptomatic bradycardia is present, apply transcutaneous pacemaker and collaborate with physician for insertion of transvenous pacer wire. Administer a dopamine infusion if patient is hypotensive. Note: Atropine must be used with great caution (if at all) with this rhythm. Atropine will increase the sinus note discharge, but does not improve conduction through the AV node, (the location of this block is lower in the conduction system). Acceleration of the atrial rate may result in a paradoxical slowing of the ventricular rate, thereby decreasing the cardiac output.