EP III and IV Flashcards
Findings favoring the diagnosis of ventricular tachycardia
History of coronary artery disease and decreased EF,
Atrioventricular dissociation,
Capture or fusion beats.
If the patient has coronary artery disease and a depressed ejection fraction (EF), the wide complex tachycardia is almost certainly ventricular tachycardia.
what are the types of ventricular beats?
Single Premature Ventricular Contractions (PVC’s)
Couplets, bigeminy and trigeminy
accelerated idioventricular rhythm (>3 ventricular beats at rate under 120 bpm)
ventricular tachycardia (>3 ventricular beats at rate over 120 bpm)
how do you treat an asymptomatic patient with wide complex beats?
none unless K or Mg levels abnormal which you should treat
how do you treat a symptomatic patient with a normal heart that has wide complex beats?
no need unless interfering with daily activities, in which case you should give a beta blocker (1st line) or antiarrhythmic
what are some problems that arise in treating patients with abnormal hearts that have wide complex beats?
treatment may be pro-arrhythmic
a Na+ or K+ channel abnormality may make treatment more dangerous
what is accelerated idioventricular rhythm?
it is a wide QRS complex beat that is slower than ventricular tachycardia
often seen in recovery of acute MI
not the same prognosis as VTach
What is ventricular tachycardia?
wide QRS complex rhythm
to differentiate from functional BBB look for AV dissociation (or fusion beats)
what is the ventricular fibrillation prognosis?
often very poor unless terminated with defibrillation (but not always)
common during cardiac arrest
The type of ventricular arrhythmia, existence of CAD, degree of LV dysfunction increase the risks
What was the Cardiac Arrhythmia Suppression Trial (CAST)?
To determine if suppression of ventricular ectopy would decrease mortality.
Patients with 6 or more PVC’s per hour, a prior MI and an abnormal EF were eligible for enrollment.
Flecainide, encainide and morizicine were compared to placebo in this population.
The CAST trial was terminated early when analysis demonstrated a worse mortality with treatment than with the placebo.
Should you use Class IC in patients with arrhythmias?
no –> increased mortality
should you use class IA drugs in patients with ventricular arrhythmias?
no
should you use use class III drugs in patients with ventricular arrhythmia?
yes: amiodarone,dl-sotalol and dofetilide
neutral effect on mortality
what is the most effective treatment for the secondary prevention of SCD?
ICD
How does ICD effect survival in vtach?
most beneficial for those with EF <35 and those with ischemia
patients with non-ischemica cardiomyopathy would benefit just as equally from amiodarone
what treatment leads to the best survival in patients with significant LV dysfunction?
ICD
what do you do for patients with ventricular arrhythmia but no evidence of CAD
drug induced long QT? most likely a QT prolonging antiarrhythmic (dofetilide)
metabolic induced?
or congenital long QT syndrom
How do you diagnose congenital long QT syndrome? What is the mortality?
prolonged corrected QT interval (Qtc) in a patient experiencing syncope with a family history of unexplained death in relatives under the age of 30. Abnormality is genetic defect in the DNA coding voltage dependent potassium channels (KVLQT1) and cardiac sodium channels (SCN5A). The mortality in the year following the onset of syncope is 20% and 50% in the following 5 years
what are the forms of congenital long QT syndrome
Romano-Ward : autosomal dominant inheritance
Jervell-Lange-Nielsen : autosomal recessive, associated with congenital deafness
what is brugada syndrome?
inherited ion channel abnormality that leads to an increased risk of sudden death is characterized by an abnormal ST segment in ECG lead V1 and V2
What are the markers of increased SCD risk in patients with hypertrophic cardiomyopathy?
Syncope or presyncope
Nonsustained ventricular tachycardia
Palpitations
Family history of sudden cardiac death.
How does scarring effect onset of arrhythmias?
Atrial scars lead to increased incidence of atrial arrhythmias, especially atrial fibrillation Ventricular scars (related to VSD repair and correction of pulmonary stenosis) predispose to ventricular arrhythmias
what drugs dor supraventricular arrhythmias respond to?
Vaughn-Williams Class Ia, Ic and III drugs
Vaughn-Williams Class II and IV may be useful if the AV node is involved
Vaughn-Williams Ib drugs do not appear to be useful in the treatment of supraventricular rhythms.
what drug has been shown to reduce the risk of stroke in patients with atrial fibrillation and flutter?
warfarin and to a lesser degree aspirin
How do you treat a symptomatic and unstable patient with atrial fibrillation
restore sinus rhythm
how do you treat a minimally or asymptomatic patient with atrial fibrillation?
rate control or rhythm control
how do you treat recurrent paroxysmal atrial fibrillation?
anticoagulation and rate control
how do you treat recurrent persistent atrial fibrillation?
anticoagulation and rate control
how do you treate a patient with atrial fibrillation and disabling symtoms?
antiarrhythmic drug
how do you treat a patient with permanent atrial fibrillation?
anticoagulation and rate control
what is cardioversion and what do you use it for?
use electricity of drugs to restore of sinus rhythm
how long after return to sinus rhythm should a patient remain on anticoagulants?
3 weeks
what is ablation therapy?
RF energy applied to critical portion of tachycardia circuit
For AV node reentrant tachycardia and SVT associated with WPW, the cure rate is > 95% with ablation.
What are Class I indications for Brady Therapy (pacemaker therapy)
Symptomatic Bradycardia,,
Asystole > 3.0 seconds
Symptomatic complete or high grade AV block,
Asymptomatic complete heart block with an escape rate < 40 bpm.
What are Class I indications for Tachy Therapy - defibrillator (ICD) therapy
Sudden cardiac death not due to a transient or reversible cause,
Sustained, spontaneous VT,
Severe LV dysfunction that persists despite appropriate therapy.
