Bradycardia Flashcards

What degree of block is typically regarded as the most crucial and therapeutically significant?

Answer: third-degree AV block

Third-degree (complete) AV block is considered the most crucial and therapeutically significant because there is a complete dissociation between atrial and ventricular activity, leading to a very slow, unreliable ventricular escape rhythm. This often results in severe bradycardia, hemodynamic instability, and requires immediate intervention, typically pacing. First-degree and Mobitz I blocks are generally less severe and often asymptomatic.

In what medications does the Bradycardia Algorithm involve?

Answer: atropine, epinephrine, dopamine

The ACLS Bradycardia Algorithm primarily involves atropine as the first-line drug for symptomatic bradycardia. If atropine is ineffective, or if the bradycardia is severe, epinephrine or dopamine infusions are recommended as second-line agents to increase heart rate and improve perfusion while preparing for transcutaneous pacing. Lidocaine and adenosine are used for tachyarrhythmias, not bradycardia.

Bradyarrhythmia is characterized by:

Answer: any rhythm disorder with a heart rate of less than 60 beats per minute

By definition, bradycardia (or bradyarrhythmia) refers to any heart rhythm disorder where the heart rate is less than 60 beats per minute. While symptomatic bradycardia often involves rates below 50 bpm, the general definition of bradycardia starts at <60 bpm, indicating a slower-than-normal heart rate.

There is symptomatic bradycardia when ___________.

Answer: all of the above are needed for symptomatic bradycardia to exist.

Symptomatic bradycardia is diagnosed when a patient exhibits a slow heart rate (bradycardia), experiences symptoms (e.g., hypotension, altered mental status, chest pain, signs of shock), AND these symptoms are directly caused by the slow heart rate. All three components must be present to define symptomatic bradycardia and warrant intervention according to ACLS guidelines.

Acutely altered mental status, shock-like symptoms, and ischemic chest pain are all bradycardia symptoms.

Answer: True

Acutely altered mental status, shock-like symptoms, and ischemic chest pain are all classic signs and symptoms of poor perfusion resulting from a slow heart rate, indicating symptomatic bradycardia. Acutely altered mental status signifies decreased cerebral perfusion, shock-like symptoms indicate systemic hypoperfusion, and ischemic chest pain suggests myocardial oxygen demand exceeding supply due to inadequate cardiac output.

Hypotension and sudden heart failure are symptoms of symptomatic bradycardia.

Answer: True

Symptomatic bradycardia occurs when a slow heart rate leads to inadequate cardiac output, causing various signs and symptoms. Hypotension (low blood pressure) is a direct result of the heart not pumping enough blood, and in severe cases, this can progress to signs of heart failure or cardiogenic shock. Therefore, these are indeed critical indicators of symptomatic bradycardia requiring intervention.

The bradycardia algorithm's main decision point is the determination of:

Answer: adequate perfusion

In the ACLS bradycardia algorithm, the primary decision point is whether the patient is symptomatic or unstable due to the slow heart rate. This instability is determined by assessing signs of inadequate perfusion, such as hypotension, altered mental status, or signs of shock. While heart rate is a factor, the presence of poor perfusion dictates the urgency and type of intervention.

The recommended current milliamperes (mA) output for transcutaneous pacing is:

Answer: set 2 mA above capture dose

When initiating transcutaneous pacing, the current (mA) is gradually increased until both electrical capture (QRS complex followed by a T wave) and mechanical capture (palpable pulse) are achieved. To ensure consistent pacing and prevent loss of capture due to minor patient movement or impedance changes, the current should then be set at 2 mA above this determined capture threshold.

The demand rate for transcutaneous pacing ought to be set at:

Answer: Began at 60-80/min and adjusted dependent on the clinical outcome.

For transcutaneous pacing, the initial demand rate should typically be set between 60-80 beats per minute. This range is generally sufficient to improve cardiac output and alleviate symptoms of bradycardia. The rate should then be adjusted based on the patient's clinical response, aiming for the lowest effective rate that resolves symptoms and maintains adequate perfusion.

You should check the carotid pulse after starting external pacing to ensure mechanical capture.

Answer: FALSE

Checking the carotid pulse is often unreliable during transcutaneous pacing because the strong electrical impulses can cause muscle contractions in the neck, which may be mistaken for a true pulse. To confirm mechanical capture, it is more reliable to assess a peripheral pulse (e.g., femoral or radial), blood pressure, or end-tidal CO2 for signs of improved perfusion. These methods provide a more accurate assessment of the heart's pumping effectiveness.

Which of the following requires transcutaneous pacing (standby pacing) preparation?

Answer: all of the above

Transcutaneous pacing (TCP) should be prepared and available for patients with symptomatic bradycardia, especially those at high risk for progression to complete heart block or asystole. This includes conditions like third-degree AV block, Mobitz type II second-degree AV block, and unstable sinus bradycardia, as these rhythms can lead to severe hemodynamic compromise requiring immediate pacing intervention. Therefore, all listed conditions warrant preparation for TCP.

What is the bradycardia algorithm's epinephrine infusion rate?

Answer: 2-10 micrograms/min

In the ACLS bradycardia algorithm, if atropine is ineffective and pacing is unavailable or ineffective, an epinephrine infusion may be considered for symptomatic bradycardia. The recommended infusion rate for epinephrine in this context is 2-10 micrograms per minute. This dosage helps to increase heart rate and myocardial contractility, thereby improving cardiac output and perfusion.

What would you do if transcutaneous pacing and medication don't work?

Answer: Transvenous pacing

If initial interventions for symptomatic bradycardia, such as atropine, transcutaneous pacing, and chronotropic infusions, fail to improve the patient's condition, the next step in the ACLS algorithm is to consider transvenous pacing. Transvenous pacing is a more invasive but often more effective and reliable method for long-term pacing in refractory bradycardia. It involves inserting a pacing wire directly into the heart via a central vein.

The next rhythm is a whole block. Which entire block definition is correct.

Answer: There is no obvious connection between P waves and QRS complexes, and the impulse produced in the SA node of the atrium does not spread to the ventricles.

A complete heart block, also known as third-degree AV block, is characterized by a total dissociation between atrial and ventricular activity. The SA node fires normally, producing P waves, but none of these impulses are conducted to the ventricles. Instead, the ventricles are paced by an escape rhythm originating from a lower pacemaker site, resulting in independent atrial and ventricular rates with no consistent PR interval.

Which of the subsequent statements is false?

Answer: second degree AV block type II=Mobitz I

The statement 'second degree AV block type II = Mobitz I' is false. Second-degree AV block Type I is known as Wenckebach, characterized by a progressively lengthening PR interval followed by a dropped QRS complex. Second-degree AV block Type II (Mobitz II) is characterized by a constant PR interval with intermittent, unexpected dropped QRS complexes, indicating a more severe block.

Determine the following rhythm.

Answer: sinus bradycardia

Sinus bradycardia is an electrocardiographic rhythm originating from the sinoatrial (SA) node, characterized by a regular rhythm, normal P waves preceding every QRS complex, and a heart rate below 60 beats per minute. All other parameters, such as PR interval and QRS duration, are typically within normal limits. This rhythm indicates a slower-than-normal but otherwise physiologically appropriate heart rhythm originating from the heart's natural pacemaker.