click below
click below
Normal Size Small Size show me how
Cardiac EP IV
Cardiac Electrophysiology IV--evaluation and tx
Question | Answer |
---|---|
What is the first tool used in the evaluation of a patient with palpitations? | The 12 lead ECG |
What are the pros + limitations of using an ECG? | painless, widely available, inexpensive; single 10 sec recording of the heart rhythm |
If the heart beat doesn't occur within the 10 sec of an ECG, what can be used to monitor for up to 24 hours (noninvasive)? | Holter or Ambulatory monitoring; can provide beat by beat analysis of the rhythm; most helpful if symptoms occur at least once every 24 hours |
When should loop recorders be used? What are the limitations of using a loop recorder? | Useful if symptoms less frequent (once ever 2-6 weeks); patient wears recorder and activates it (must be conscious) when they get symptoms; information transmitted via telephone to central station |
What's an alternative to a loop recorder if the patient is frail or if the symptom includes frank syncope? | Implantable loop recorder automatically activate when it senses pauses, slow, or fast heart rates; DOES REQUIRE SUBCUTANEOUS IMPLANTATION |
When is signal averaged ecg useful? What types of ECG abnormalities affect the reliability of the measurement? | Assessment of risk for significant ventricular arrhythmias and predicting mortality after an MI. Specificity is decreased with baseline conduction abnormalities. |
What is heart rate variability (HRV) technique useful for? | examines cyclic changes in HR; time between consecutive beats analyzed in either time or frequency domain; decreased HRV may predict arrhythmic events |
What is decreased parasympathetic activity to the heart associated with? | increased mortality; inspect using Heart rate variability (HRV) |
What is the T-wave alternas method? What is it useful for? | Looks at microvolt changes in T-wave amplitude; studies suggest that negative predictive power of test could be used to identify low risk population |
What is the gold standard for the evaluation of cardiac arrhythmias? | The electrophysiology study (EP); invasive |
What information does the EP study provide? | Assessment of 1) SA and AV node function, 2) intracardic conduction times and localization of heart block 3) reproducing reentrant arrhythmias 4) mapping of circuits reponsible for abnormal rhythm, 5) 3D mapping of heart circuits |
Vaughn-Williams Class I drugs | Essentially Na+ Channel blockers: Procainamide, Quinadine, Disopyramide |
Vaughn-Williams Class II drugs | Beta adrenergic blockers |
Vaughn-Williams Class III | K+ channel blockers |
Vaughn-Williams Class IV | Ca++ channel blockers |
What 2 notable antiarrhythmics do not fit in the Vaughn-Williams classification? | Adenosine and digoxin |
Vaughn-Williams Class IA drug actions | increase AP duration and ERP, increased QRS and QT duration, decreased slope phase 0 |
Vaughn-Williams Class IB drug actions | decreased AP and QT duration; no change in ERP; decreased slope phase 0 |
Vaughn-Williams Class IC drug actions | no change in ERP and A duration; decreased slope phase 0 & 4 |
Vaughn-Williams Class II drug actions | Decreased AV conduction, increased AV nodal refractoriness, decreased chronotropy |
Vaughn-Williams Class III drug actions | Increase AP duration and ERP; increased PR interval; increased QRS duration; increased QT duration |
Vaughn-Williams Class IV drug actions | Increased ERP of AV node, blocks slow Ca++ channel current |
Vaughn-Williams Class I side effects | GI distress, CNS symptoms, allergic reactions, lupus, thrombocytopenia, pro-arrhythmias, syncope |
Vaughn-Williams Class II side effects | Hypotension, Bradycardia, worsening CHF, worsening asthma or COPD |
Vaughn-Williams Class III side effects | Amidarone: pulmonary toxicity, bradycardia, GI symptoms, thyroid and liver abnormalities. Sotalol: All class II side effects + proarrhythmia. Dofetilidie: torsade de Pointes |
Vaughn-Williams Class IV side effects | Hypotension, bradycardia, worsening AV lock, Liver function abnormalities |
In general, what Tx are available for patients with supraventicular arrhythmias? What if AV node is involved? | VW Class Ia, Ic, and III drugs; II and IV if AV ivolved; Ib do not appear useful |
How do you treat atrial fibrillation? | Prevent embolic complications and treat abnormal rhythm |
With afib, what risk factors are associated with high risk for stroke? Moderate? Low? | RHEUMATIC VALVULAR DISEASE. CHF within last 3 months, history of hypertension or arterial thromboemboli, global LV dysfunction, LA size > 4.7 cm, left sided valvular abnormalities. No risk factors and < 60 yoa |
What two drugs have been shown to been effective in reducing the risk of stroke in patients with afib? | Warfarin (coumadin) and aspirin; warfarin shown to lower risk the most. |
CHADS2 risk factors | Prior stroke or TIA (high); Age>75 yoa, hypertension, diabetes mellitus, heart failure |
How should you treat a patient with afib that is symptomatic and unstable? Minimally or asymptomatic? | Symptomatic + unstable: restore sinus rhythm; Minimally/asymptomatic: rate control or rhythm control |
Anticoagulation and rate control are needed for: | recurrent paroxysmal atrial fibrillation and recurrent persistent atrial fibrillation |
Antiarrhythmic drug therapy is needed for A.fib. patients if: | disabling symptoms are present |
What are the only recommendations for patients with permanent atrial fibrillation? | Anticoagulation and rate control |
What are some of the advantages + disadvantages of using digoxin for rate control during a.fib.? | Advantages: inexpensive, widely available. Disadvantages: poorly controls rate during activity, digitalis toxicity serious problem |
What are some of the advantages + disadvantages of using beta and calcium channel blockers for rate control during a.fib.? | Advantages: controls rate well during activity, relatively inexpensive, widely available. Disadvantages: effective rate controlling doses can have intolerable side effects |
What are some of the advantages + disadvantages of using amiodarone for rate control during a.fib.? | Advantages: may help restore sinus rhythm, widely available. Disadvantages: pulmonary and thyroid side effects, interactions with other drugs (e.g. warfarin), can lead to bradycardia, long half-life |
What are some of the advantages + disadvantages of using AV node ablation for rate control during a.fib.? | Advantages: complete control of ventricular rate. Disadvantages: requires life long permanent pacemaker |
How do you treat atrial fibrillation in a patient with Wolff-Parkinson-White Syndrome? | AVOID DIGOXIN, as blocking AV node allows atrial activity to escape through accessory pathway; treat with procainamide to slow both AV node and accessory pathway |
How do you treat VT in patients with CAD? | ICD shown to be more effective than drug therapy (amiodarone not as effective as ICD in both ischemic and non-ischemic pop) |
How do you treat patients with AV node reentrant tachycardia and SVT associated with WPW? | Ablation therapy: radiofrequency energy applied to critical portion of the tachycardia circuit; very low morbidity and almost no mortality |
Ablation therapy can be used to treat... | Supraventricular tachycardias and ventricular tachycardias |
Brady Theray-pacemaker therapy | Class I indications: symptomatic bradycardia; asystole > 3.0 seconds; symptomatic complete or high grade AV block; asymptomatic complete heart block with an escape rate <40 bpms |
Tachy therapy--defibrillator (ICD) therapy | Class I Indications: sudden cardiac death not due to transient or reversible cause; sustained, spontaenous VT; severe LV dysfunction that persists despite appropriate therapy |
How would you treat a patient with BBB and 1) Class III or IV CHF despite optimal medical therapy, 2) Ejection fraction less than 36%, and 3) QRS that is at least 120 ms in duration | Bi-ventricular pacing; up to 75% show improvement with reduction in LV size and increases in LV ejection fraction |