Cardio Exam 3: Tsu Arrhythmias Pre-Work

Heart Rate → Determined by ______

• Normal SA Node pacing is ______ bpm

• SA node pacing <60 bpm is bradycardia

• SA node pacing >100 bpm is tachycardia

SA node, 60-100

Abnormal Heart Rhythms

• Bradycardia → ______

• Supraventricular arrhythmias → ______

• Ventricular arrhythmias → ______

AV blocks, Aflutter, Afib, and SVT, Vtach, Torsades de Pointes, and Asystole

3 Types/Degrees of AV Blocks

• 1st degree (______ severity of Sxs)

• 2nd degree

  • Mobitz type 1 (Wenckebach)

  • Mobitz type 2

• 3rd degree (______ severity of Sxs)

low, high

______

• Impulse conduction slowed (partial block) at AV node for a fixed interval

• Usually asymptomatic

• Common etiologies

• Many due to drugs: usually the AV nodal blockers (BBs, non-DHP CCB, digoxin)

• Any condition that stimulates the parasympathetic nervous system (e.g. vasovagal reflex)

• PR >0.2 seconds all P waves conduct through (followed by QRS complex)

1st Degree AV Block

1st Degree AV block

• Impulse conduction ______ (partial block) at AV node for a fixed interval

• Usually ______

• Common etiologies

• Many due to drugs: usually the AV nodal blockers (______)

• Any condition that stimulates the ______ (e.g. vasovagal reflex)

• PR >0.2 seconds ______ (followed by ______)

slowed, asymptomatic, BBs, non-DHP CCB, and digoxin, parasympathetic nervous system, all P waves conduct through, QRS complex

2nd Degree AV block

• Mobitz type 1 (Wenckebach)

  • ______, and then ______ fails to follow

  • Which means lost ______ → ______

  • Usually ______

  • Can be due to drugs (AV node blockers) or parasympathetic nervous system

conduction progressively slows at AV node, QRS complex, ventricular contraction, decreases CO, asymptomatic

2nd Degree AV block

• Mobitz type 2

  • ______ the AV node

  • ______ is regular

  • Can be symptomatic if ______

  • ______ = constant + random ______ are dropped

  • Note in Mobitz type 1, it’s a ______, whereas here it is ______

block is below, atrial rate, bradycardia, PR interval, QRS complexes, predictable dropping of QRS complexes, random timing

______

• Complete heart block

• “AV” dissociation: atrium + ventricles are independent

• No P waves are conducting

  • Ventricle = 30-40 BPM when it is not receiving input from SA node so patients are generally symptomatic due to the bradycardia

• Requires pacemaker to control the ventricular rate

3rd degree AV block

3rd Degree AV Block

• ______

• “AV” dissociation: atrium + ventricles are ______

• ______ are conducting

  • ______ = 30-40 BPM when it is not receiving input from SA node so pts are generally symptomatic due to the ______

• Requires ______ to control the ventricular rate

complete heart block, independent, No P waves, Ventricle, bradycardia, pacemaker

AV Block Treatment

• Depends on ______

• Remove cause of AV block, if applicable

• Permanent pacemaker

severity of Sxs,

Question:

• A gradual lengthening of the PR interval leading to a predictable drop in a QRS complex is called ______ AV block.

2nd degree Mobitz 1

Paroxysmal Supraventricular Tachycardia (PSVT)

• ______, ______ firing of SVT ______ focus

• Rate usually ~______

• May appear as fast rate with ______ or ______

• Foci impulses are usually conducted through to ______

sudden, rapid, automaticity, 150-250, absence of P waves, abnormal-looking P waves, ventricles

PSVT Management

• Non-pharm therapy

  • Mild-Moderate Sxs

    • ______

      • ______, ______, ______ 

  • Severe Sxs (eg. ______)

    • ______

Vagal Techniques, carotid sinus massage, valsalva maneuver, ice water facial, syncope, angina, and HF, Direct Current Cardioversion (DCC)

PSVT Management

• Pharmacological therapy

  • ______ → ______

  • Depress conduction through ______, ______-dependent tissue → ______

  • Depress conduction through ______, ______-dependent tissue → ______

Increases vagal tone, digoxin, slow, Ca, Adenosine, BB, and non-DHP CCB, fast, Na, Quinidine, Procainamide, Disopyramide, and Flecainide

Radiofrequency Ablation

• Destroys ______ pathway

• ______ in 85-98% of patients

• Replaces need for anti-arrhythmic therapy 

accessory, prevents PSVT

Question: Which statement is most accurate regarding SVT?

1. It is usually caused by SA node reentry

2. Mild symptoms can be treated with vagal maneuvers

3. Nodal blocking medications are more effective than ablation

4. Most medications work by blocking the K channel

2

QT interval

• Measured from the beginning of the ______ to the end of the ______

• The QT interval varies with ______

• When the ______ ↑, ______ ↓

• A ______ QT interval can predispose pts to the formation of dangerous rhythms (e.g. ______)

• The QT interval should be corrected for differences in ______

• The QTc or “corrected QT” can be calculated using Bazett’s formula

• Prolonged QTc:

  • Males: >450 msecs

  • Females: >460 msecs

  • Highest risk of TdP >500 msecs

• QTc prolongation

  • Genetic, electrolyte abnormalities, many meds

    • Really important for pharmacists to monitor

    • Increases risk of TdP

QRS complex, T wave, HR, HR, QT interval, prolonged, torsades de pointes, HR

Question: Which statement regarding QT and QTc intervals is most accurate?

1. QT is related to QTc by correcting for the variability in heart rate

2. Prolonged QT, but not QTc, increases risk for torsades de pointes

3. There is highest risk of TdP when QTc > 400 msecs

1

______ is the most common sustained atrial arrhythmia

• The focus of our in-class lecture will be on this topic

• Two main issues to treat

  • Stroke prevention with ______

  • Treatment of tachyarrhythmia Sxs with ______

Purpose: Calculate this score in ______. to determine their ______, and therefore if they need anticoagulation

Afib, anticoags, rate and rhythm control, all pts with Afib, risk of stroke

• GH is a 76 year old, 74 kg Caucasian female how is newly diagnosed with AF. Her past medical history is significant for hypertension, diabetes, myocardial infarction 2010, and overactive bladder. Her medications include amlodipine, metoprolol, metformin, glyburide, aspirin, and oxybutynin.

• Vitals: BP 136/84 mmHg, HR 72 bpm, RR 18

• Labs: Scr 1.1 (WNL), LFTs 40/52 (WNL), K 4.5 (3.5 – 5.0), Na 138 (135 – 145 )

What is GH’s CHADS2-VASc score?

6

• GH is a 76 year old, 74 kg Caucasian female how is newly diagnosed with AF. Her past medical history is significant for hypertension, diabetes, myocardial infarction 2010, and overactive bladder. Her medications include amlodipine, metoprolol, metformin, glyburide, aspirin, and oxybutynin.

• Vitals: BP 136/84 mmHg, HR 72 bpm, RR 18

• Labs: Scr 1.1 (WNL), LFTs 40/52 (WNL), K 4.5 (3.5 – 5.0), Na 138 (135 – 145 )

What do you recommend for antithrombotic therapy for GH?

Oral Anticoagulant, such as Warfarin or DOACs (dosing for prevention of stroke in Afib is different than for treatment of VTE)