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CVPR: CV Unit I > Arrhythmias > Flashcards

Flashcards in Arrhythmias Deck (13):

EKG features of normal sinus rhythm

  • a normal P wave (atrial depolarization), PR interval (resistance to conduction at the AV node), QRS complex (ventricular depolarization), and a T wave (ventricular repolarization).

  • Normal sinus rate in adults is 60-100 bpm. 

  • Normal PR interval is 0.12-0.20 seconds. 

  • Widening of the QRS, preceded by a normal P wave and a normal PR interval→rhythm is still sinus. 

  • Rate and regularity of rhythm may vary slightly with respiration.


Sinus tachycardia definition/common conditions

  • regular, fast heart rate (>100 bpm)
  • commonly occurs during exercise or emotional stress
  • no treatment is generally needed, but in patients with coronary artery disease the increased cardiac oxygen demand may precipitate angina
  • Sinus tachycardia is associated with hyperthyroidism.
  • If treatment is needed, a beta-blocker is usually effective.


Sinus bradycardia definition/common conditions

  • regular, slow heart rate (<60 bpm)
  • common in normal individuals, especially athletes and requires no treatment
  • Sinus bradycardia may produce syncope during intense vagal activation as in fainting for which atropine is an effective tx
  • Often occurs with small inferior wall infarctions that increase vagal tone.
  • Can cause syncope, lightheadedness or fatigue in elderly patients with age-related dysfunction→sick sinus syndrome. Treatment may require placement of an electronic pacemaker.


Atrial rhythms definition

  • rhythms originating in the atria
  • e.g. atrial fibrillation or atrial flutter


Junctional (nodal) rhythms definition

  • Regular, narrow (normal) QRS complex with no antecedent P waves.

  • region surrounding the AV node = “junction” and rhythms originating there are called junctional rhythms. 

  • They may be either slow or fast. They are a regular rhythm usually with narrow QRS complexes. 

  • P waves are often not seen because they are buried within the QRS complex or they may occur very shortly before or after the QRS.  

  • P waves that are seen often inverted because they are conducted upward from the AV node rather than downward from the SA node.


Ventricular rhythm

  • rhythms originating in the ventricle
  • e.g. ventricular tachycardia or ventricular fibrillation


Causes, EKG features of first-degree AV block

  • Causes: drug-induced (beta-blockers, some calcium blockers, digitalis), conduction system disease.
  • EKG features: PR interval is greater than 0.2 seconds (one large block on the EKG).

  • This is a benign condition that can proceed to more serious types of block.


Causes, EKG features of second-degree AV block

  • Causes: conduction system disease, high vagal tone, excessive effects of drugs.
  • EKG features: Some P waves conduct normally to ventricles but others do not. Patterns vary.
  • If the rate is too slow to slow to support cardiac output adequately, syncope or confusion may occur requiring a pacemaker.


Causes, EKG features of third-degree AV block

  • Causes: av node or junctional failure with aging, infarct or disruption during cardiac surgery—rarely caused by drugs.

  • EKG features: Both Ps and QRSs show regular rhythm, but they are at different rates. With P rate > QRS rate.

  • May cause syncope or sudden death. Usually requires a pacemaker.


Causes, EKG features, clinical manifestations, and tx of atrial fibrillation

  • EKG features: irregularly irregular ventricular rhythm. No p waves.

  • Causes: NI subjects, aging, post-operative, heart disease, hyperthyroidism

  • Clinical manifestations: rapid heart rate (syncope, ischemia, heart failure), loss of atrial kick (heart failure), atrial thrombi (embolic stroke).

  • Treatment: anticoagulation, rate control with drugs, cardioversion—electrical or drugs, ablation.


Causes, EKG features, clinical manifestations, and tx of atrial flutter

  • EKG features: P waves (flutter waves) at rate of 240-320 bpm. Pulse may be regular or irregular. Ventricular rates vary widely—typically rapid if untreated.
  • Complications: atrial flutter has some risk of embolic stroke due to clot in the left atrium, and may result in rapid ventricular rates that are poorly tolerated.
  • Treatment: anticoagulation, rate control with drugs, cardioversion, ablation.


Causes, EKG features, clinical manifestations, and tx of ventricular tachycardia

  • EKG features: repetitive wide-abnormal QRS complexes, no p-wave
  • Causes: fibrosis, infiltrate, dilation, long path length permitting reentry.
  • Clinical manifestations: very bad. Abnormal ventricular contraction
  • Treatment: emergency defibrillation.


Causes, EKG features, clinical manifestations, and tx of ventricular fibrillation

  • EKG features: abnormal, abnormal, abnormal—all noise, no p waves, no QRS complexes, no T waves.
  • Causes: can progress from ventricular tachycardia. Heart failure.
  • Clinical manifestations: very bad. No ventricular contraction.
  • Treatment: immediate emergency defibrillation.