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Ventricular Rhythms
Cardiac Electrophysiology III: ventricular rhythms
| Question | Answer |
|---|---|
| What two things should you consider with fast, wide QRS complex rhythms? | Ventricular tachycardia (ominous) or supraventricular tachycardia with aberrant conduction (functional bundle branch block) |
| What factors favor diagnosis of ventricular tachycardia in a fast, wide QRS complex rhythm? | 1) history of coronary artery disease and decreased EF, 2) Atrioventricular dissociation, 3) Capture or "fusion" beats. Almost sure if there is history of CAD and depressed ejection fraction (EF) |
| What are the forms in which ventricular ectopic beats typically manifest on an ECG? | Single premature vetricular contraction (PVC), couplets (two ventricular beats in a row), bigemy or trigemy (every 2nd or 3rd beat is a ventricular ectopic beat); accelerated idioventricular rthym, ventricular tachycardia, ventricular fibribillation |
| If wide complex beats are seen in a normal heart, how should you treat it? | No evidence that treatment of ventricular arrhythmias (PVCs) improves excellent prognosis (benign); need no therapy. If K or Mg levels abnormal, replacement therapy may help. If symptomatic: beta blockers (1st line) or antiarrhythmics, though unecessary |
| What possible problems should you watch out for in treating wide complex beats in patients with an abnormal heart? | Pro-arrhythmic effects of drugs or Na+ or K+ channel abnormalities (e.g. long QT syndromes) |
| When are accelerated idioventricular rhythms (Slow V Tach) seen? | (80 bpm) In recovery phase of an acute MI; doesn't have same prognosis as ventricular tachycardia; difference from VT is slight. |
| What causes a fusion or "fusion" beat? What diagnosis does it favor? | Seen in AV dissociation, it occurs when ventricle simultaneously activated by native conductive system and the ventricular beat. |
| What does ventricular fibrilation look like on an ECG? Prognosis? Typically seen when? | Fast (~300 bpm); looks like sawtooth pattern; poor prognosis (but they are not all the same!); rhythm seen in cardiac arrest |
| What 3 things determine the mortality of a ventricular arrhythmia? | 1) type of ventricular arrhtyhmia, 2) existence of CAD, 3) degree of LV dysfunction |
| The CAST study found that administering flecainide, encainide, and morizicine to patients with >6 PVC's/hour resulted in ___ mortality compared to placebo | worse |
| Should Class IC drugs be used to treat arrhythmias? Why or why not? | NOT (atrial or ventricular) in patients with CAD and a decreased EF because of increased mortality in this population |
| Should Class IA drugs be used to treat arrhythmias? Why or why not? | Should be avoided, as well as sodium channel blockers |
| What antiarrhythmic drugs appear to be ok to give to patients? | Class III (Amiodarone, d,l-sotalol, and dofetilide) since they do not appear to increase mortality |
| What is the predictive value of EPS and Holter at predicting drug efficacy for suppression of VT? | Not very good |
| All available atiarrhythmic drugs except for ___, ___, and ___ increase mortality in the post MI population | Amiodarone, sotalol, dofetilide; these drugs only have a "neutral" effect on mortality |
| In survivors of sudden cardiac death (SCD), or sustained ventricular tachycardia, do ICD or antiarrhythmics provide lower mortality? What type of prevention is this? | ICDs provide lower mortality; SECONDARY PREVENTION |
| What's the recommendation for primary prevention for patients succeptible for ventricular tachycardia in CAD? | Patients with significant LV dysfuction regardless of etiology should be considered for ICD therapy (primary prevention) even without observed ventricular ectopy |
| What ECG abnormality is associated as a risk factor for Torsade de Pointes? | Long QT interval |
| How do you make the diagnosis of acquired (drug induced) long QT syndrome? What are the possible causes? | Prolonged corrected QT interval (QTc) in a patient without prior evidence of a long QT interval; can be due to drugs or metabolic imbalance |
| What is the most common cause of acquired long QT syndrome? | Use of QT prolonging antiarrhythmic drug |
| How do you make the diagnosis of congenital long QT syndrome? | Prolonged corrected QT interval (Qtc) ina patient with syncope with a family history of unexplained death in relatives under the age of 30 |
| What genetic defect causes congenital long QT syndrome? | Genetic defect in DNA coding voltage dependent K+ channels (KVLQT1) and cardiac Na+ channels (SCN5A) |
| What are the two forms of congenital long QT syndromes and how are they inherited? | Romano-Ward (autosomal dominant); Jervell-Lange-Nielsen (autosomal recessive; associated with congenital deafness) |
| Brugada syndrome: type of disorder; how is it diagnosed? | Inherited ion channel abnormality; leads to increased risk of sudden death; characterized by abnormal ST segment in ECG lead V1 and V@ |
| What other conditions (4) are at higher risk for ventricular arrhythmias in the abscence of ischemic and non-ischemic cardiomyopathies? | Mitral valve prolapse; hypertrophic cardiomyopathy; patients post surgical valve replacement; corrected congenital heart disease |
| Mitral valve prolapse management: risk of sudden death; work up; warning signs; treatment | low (non-zero) incidence of SCD; work up unwarranted unless palpitations, presyncope, or syncope present (Holter or Event recorder or EP study); risk mostly due to mitral regurg and LV dysfunction; beta blockers |
| Hyptertrophic cardiomyopathy management: risk of sudden death; work up; warning signs; treatment | Increased risk for SCD; markers: syncope or presyncope, nonsustained ventricular tachycardia, palpitations, FH of SCD; EP study and guided therapy only if these risk factors present |
| Post aortic valve replacement: risk of sudden death; work up; warning signs; treatment | 15% to 20% of late deaths follow aortic valve replacement sudden; may be due to VT, as increased ectopy following aortic valve replacement; may benefit from EP study if symptomatic palpitations arise |
| Adults with corrected congenital heart disease: what congenital heart defect most at risk of sudden death; work up; warning signs; treatment | Tetralogy of Fallot (most likely to see in clinical practice); atrial scars increased incidence of atrial arrhythmias (esp afib); ventricular scars may lead to VT; more extensive repairs --> increased risk for Vent. arrhythmias |
Created by:
karkis77
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