Clinical Electrophysiology IV Flashcards
1
Q
Evaulation of Cardiac Arrhythmias
- Symptoms due to an abnormal rhythm
- Goal of arrhythmia evaluations
A
- Symptoms due to an abnormal rhythm
- Palpitations: unusual awareness of the heart beta
- Tachycardia: rapid heart beat
- Syncope: loss of consciousness
- Presyncope: dizziness, lightheadedness
- Chest pain
- Goal of arrhythmia evaluations
- Correlate symptoms w/ rhythm abnormality
2
Q
12 Lead ECG
- General
- Assessment
- Pros
- Cons
A
- General
- Noninvasive tool
- First step
- Assessment
- Heart rate
- Conduction disease or abnormalities like WPW syndrome
- Evidence of a prior MI
- Evidence of various atrial or ventricular arrhythmias
- Pros
- Painless
- Widely available
- Inexpensive
- Cons
- Limited to a single 10 second recording of heart rhythm
3
Q
Ambulatory or Holter Monitoring
- General
- Assessment
- Pros
- Cons
A
- General
- Noninvasive tool
- Records heart rhythms for 24 hours
- Assessment
- Frequency of ectopic beats
- Average heart rate
- Episodies of tachycardia & bradycardia
- Pros
- Can see if the rhythm distrubances or symptoms occur at least once during the 24-hour period
- Cons
- Possible to miss an arrhythmic episode if an event doesn’t occur during the 24-hour period
- may fail to correlate symptoms w/ an abnormal rhythm
4
Q
Patient Activated Event (“Loop,” “King of Hearts”) Recorders
- General
- Pros
- Cons
A
- General
- Noninvasive tool
- Patients activate the recorder when they feel symptoms
- Rhythm recorded on the device is transmitted via telephone to the central station for interpretation
- Pros
- Assesses symptoms that occur less than daily buare are likely to occur ina reasonable period of time
- Cons
- Patients may not be able to activate the recorder at the time of the symptoms due to physical frailty or syncope
5
Q
Implantable Loop Recorder
A
- Noninvasive tool
- Automatically records when it senses pauses, slow or fast HRs, or when the patient notices symptoms
6
Q
Cardionet
- General
- Pros
A
- General
- Noninvasive tool
- External loop recorder
- Wearable monitor w/ a base unit that continuously transmits the rhythm to a central monitoring center for interprtetation & monitoring
- Pros
- Good for patients that may not have time to activate a monitor prior to syncope or who don’t “feel” the arrhythmia (ex. atrial fibrillation)
7
Q
Signal Average ECG (SAECG)
- General
- Assessment
- Cons
A
- General
- Noninvasive tool
- Based on the assumption that areas of arrythmogenic ventricular muscle exhibit slow conduction that will be manifested as small potentials near the end of the QRS complex
- Late potentials aren’t seen on the avg ECG b/c of filtering that limits noise
- If hundreds of QRS complexes are averaged, the “random noise” is cancelled out & these “late potentials” can be seen
- Assessment
- Assesses patient’s risk of sudden cardiac death
- Predicts future mortality after a MI
- Not correlated w/ a symptom
- Cons
- Specificity is decreased if a patient has a baseline conduction abnormality (ex. BBB) or the noise level of the SAECG > 0.5
8
Q
Heart Rate Variability (HRV)
- General
- Methods
- Assessment
- Pros
A
- General
- Noninvasive tool
- Looks at cyclic changes in HR by analyzing the time b/n consecutive heart beats
- Methods
- Standard statistical methods
- Time domain analysis
- Transformation into the frequency domain
- Uses the Fast Fourier Transform
- Frequency domain analysis
- Standard statistical methods
- Assessment
- Arrhythmic risk
- Decreases in parasympathetic (primarily vagal) activity are associated w/ increased mortality in post-MI patients
- Pros
- Decreased HR variability better predicts arrhythmic events than the SAECG, stress test, or EF measurements
9
Q
T Wave Alternans
- General
- Assessment
A
- General
- Noninvasive tool
- Look sfor microvolt changes in the size of the t wave
- Alternating patterns of big & small amplitude t waves correlate w/ an increased risk for ventricular arrhythmias
- Assessment
- Patients who aren’t at risk for cardiac arrhythmias
10
Q
Electrophysiology (EP) Study
- General
- Method
- Programmed electrical stimulation
- Specialized studies
A
- General
- Invasive tool
- Gold standard for evaluating cardiac arrhythmias
- Method
- Insert catheters to record intracardiac signals from critical regions of the cardiac conducting system
- Catheters are normally placed near the SA node, AV node, Bundle of His, & RV apex
- Programmed electrical stimulation
- Catethers introduce pacing sitmuli & record to study the conducting system or induce arrhythmias (typically those w/ a reentrant mechanism)
- Specialized studies
- Catheters are placed into hte LV, LA, or coronary sinus
- Recordings of conduction times & location where conduction fails or is blocked allows assessment of SA & AV nodal function
- Determiens the need for a permanent pacemaker
11
Q
Computer Based Mapping Systems
A
- Invasive tools
- Introduce extra stimuli to reproduce reentrant arrhythmias
- Ex. VT associated w/ CAD, many types of SVT
- Map the location of the focus or circuit responsible for the abnormal rhythm
- Use GPS-like technology to construct 3D images of cardiac activation
- Speeds ablation
- Makes it possible to perform new procedures
12
Q
Vaugn-Williams Antiarrhythmic Drugs: Classification & Representative Drugs
- Class I
- IA
- IB
- IC
- Class II
- Class III
- Class IV
A
- Class I: sodium channel blockers
- IA
- Procainamide
- Quinadine
- DIsopyramide
- IB
- Lidocaine
- Mexilitine
- Tocainide
- IC
- Flecainide
- Encainide
- Propafenone
- IA
- Class II: beta blockers
- Propranolol
- Atenolol
- Metoprolol
- Timolol
- Naldolol
- Esmolol
- Class III: potassium channel blockers
- Amiodarone
- Bretylium
- NAPA
- Sotalol
- Dofetilide
- Class IV: calcium channel blockers
- Verapamil
- Diltiazem
- Nifedipine
13
Q
Vaugn-Williams Antiarrhythmic Drugs: Effects
- Class I
- IA
- IB
- IC
- Class II
- Class III
- Class IV
A
- Class I: sodium channel blockers
- IA
- Increase AP duration & Effective Refractory Period (ERP)
- Increase QRS & QT duration
- Decrease slope phase 0
- IB
- Neutral effect on ERP
- Decrease AP & QT duration
- Decrease slope phase 0
- IC
- Neutral effect on ERP & AP duration
- Decrease slope phase 0 & 4
- IA
- Class II: beta blockers
- Increase AV nodal refractoriness
- Decrease AV conduction
- Decrease chronotropy
- Class III: potassium channel blockers
- Increase AP duration & ERP
- Increase PR interval
- Increase QRS duration
- Increase QT duration
- Class IV: calcium channel blockers
- Increase ERP of AV node
- Block slow Ca2+ current
14
Q
Vaugn-Williams Antiarrhythmic Drugs: Side Effects
- Class I
- Class II
- Class III
- Amiodarone
- Sotolol
- Dofetilide
- Class IV
A
- Class I: sodium channel blockers
- *GI distress
- CNS symptoms
- Allergic reactions
- *Lupus
- Thrombocytopenia
- Pro-arrhythmia
- *Syncope (Quinidine)
- Class II: beta blockers
- Hypotension
- Bradycardia
- Worsening CHF
- Worsening asthma or COPD
- Class III: potassium channel blockers
- Amiodarone
- *Pulmonary toxicity
- Bradycardia
- GI symptoms
- *Thyroid & liver abnormalities (hypothyroidism)
- Sotolol
- Class II effects + pro-arrhythmia
- Contraindicated in patients w/ renal dysfunction
- Dofetilide
- Torsade de pointes
- Contraindicated in patients w/ renal dysfunction
- Amiodarone
- Class IV: calcium channel blockers
- Hypotension
Bradycardia - Worsening AV block
- Liver function abnormalities
- Hypotension
15
Q
Medical Therapy for Supraventricular Arrhythmias
- Treatment for supraventricular arrhythmias
- Treatment for supraventricular arrhythmias where the AV node is part of the arrhythmia circuit
- Treatment not effective in atrial rhythm abnormalities
A
- Treatment for supraventricular arrhythmias
- Class IA, IC, & III antiarrhythmic drugs
- Treatment for supraventricular arrhythmias where the AV node is part of the arrhythmia circuit
- Class IA, IC, & III antiarrhythmic drugs
- Class II & IV antiarrhythmic drugs for their AV nodal blocking properties
- Treatment not effective in atrial rhythm abnormalities
- Class IB antiarrhythmic drugs