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Understand ventricular rhythms, including origins, components, and characteristics. Learn to identify and differentiate various rhythms like PVC, VT, VF, and asystole on EKG. Clinical implications discussed.
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10 Introducing the Ventricular Rhythms
Introducing the Ventricular Rhythms • Objectives • Discuss the origin of the ventricular rhythms • Review specific components of the electrical conduction system of the heart • Identify premature ventricular contractions, including EKG characteristics • Identify idioventricular rhythm, including EKG characteristics • Differentiate idioventricular rhythm and accelerated idioventricular rhythm
Introducing the Ventricular Rhythms • Objectives (continued) • Identify ventricular tachycardia, including EKG characteristics • Identify ventricular fibrillation, including EKG characteristics • Identify ventricular asystole, including EKG characteristics • Discuss pulseless electrical activity • Discuss the clinical significance of the ventricular rhythms
Origin of the Ventricular Rhythms • The rhythms are classified according to the heart structure in which they begin, or theirsite of origin • The sinoatrial (SA) node or the AV junctional tissues fails to generate an impulse • If this failure develops,the VENTRICLES will assume the role of pacing the heart
Origin of the Ventricular Rhythms • Rhythms that are initiated in the area of the ventricular are called ventricular rhythms • Ventricular rhythms are the least efficient of the heart’s pacemakers; you should recall thatpatient assessmentis the most important indicator of clinical significance
Origin of the Ventricular Rhythms • Impulses that are ventricular in origin begin in the lower ventricular musculature • Impulse may travel in retrograde (backward) direction to depolarize the atria • Impulse may travel antegrade (forward) to depolarize the ventricles • Either way, the normal conduction pathway is bypassed
Origin of the Ventricular Rhythms • Due to bypass, ventricular rhythms will display QRS complexes that are wide (greater than or equal to 0.12 seconds)and bizarre in appearance • Absence of P waves because they are hidden or buried in QRS complex • Remember that QRS complexes of supraventricular rhythms are commonly less than 0.12 seconds in duration
Premature Ventricular Complexes (Contractions) (PVC) • Individual complexes rather than an actual rhythm • Singleectopic(out-of-place)complex that occurs earlier then the next expected complex • Arises from an irritable site in the ventricles • The significance of PVCs is based entirely upon the patient’s clinical condition
Premature Ventricular Complexes (Contractions) (PVC) Premature Ventricular Complexes (Contractions) (PVC) • The underlying cadence of SA node is not interrupted by a PVC nor is SA node depolarized • PVC is usually followed by acompensatory pause • Presence of compensatory pause, coupled with wide, bizarre, and premature QRS complex’s are highly suggestive indicators of PVCs
Premature Ventricular Complexes (Contractions) (PVC) Premature Ventricular Complexes (Contractions) (PVC) • PVC may fall between two sinus beats without interfering with the rhythm • Referred to as aninterpolated beat • PVCs appear in many different patterns and shapes • The morphology, or shape, of the PVC is based on the site of origin of the ectopic focus
Premature Ventricular Contractions (Complexes) OR PVCs • PVCs often indicate myocardial irritability; multifocal PVCs are more serious then unifocal PVCs • Salvos • Runs of ventricular tachycardia • Any indication of increased myocardial irritability dictates that the patient be carefully evaluated and managed
Idioventricular Rhythms • Also termedventricular escape rhythms,considered a last-ditch effort of the ventricles to try to prevent cardiac standstill • Means SA node and AV node have failed • Rate usuallyless than 40 bpm,and cardiac output is usually compromised
Agonal Rhythm • Agonal rhythmis when the idioventricular rhythm fallsbelow 20 bpm • Frequentlymay be seen as the last-ordered semblance of a heart rhythm when eitherresuscitation is unsuccessfulor aftersuccessful defibrillation
Idioventricular Rhythms • Causesinclude extensive myocardial damage, secondary to acute myocardial infarction, or failure of higher pacemakers • Is consideredalethal rhythmand treatment must beimmediate and aggressive
Accelerated Idioventricular Rhythm • May occur when the rate of the ectopic pacemaker exceeds40 bpm • Commonly accepted rate is40-100 bpm • There are no P waves or PR intervals noted
Accelerated Idioventricular Rhythm • May occur in conjunction with myocardial ischemia • Can be mistaken for ventricular tachycardia • Imperative that you remember toalways assess and treat the patient,rather than the monitor or EKG strip
Ventricular Tachycardia Rhythms • This rhythm is one in whichthree or more PVCs arise in sequence at arate greater than100 bpm • This rhythm commonly overrides the normal pacemaker of the heart • Often occurs rapidly and isinitiated by a PVC or by PVCs occurring in rapid succession
Ventricular Tachycardia Rhythms • If rhythm is sustained, patient’s clinical condition may rapidly deteriorate • A sustained rhythm is one that lasts for more than 30 seconds • If lasts forless than 30 seconds,it is anonsustained rhythm,or simplya run of V tach
Ventricular Tachycardia • Is classified (based on assessment of the patient’s clinical presentation)as either pulseless V tach or V tach with a pulse • Immediate treatment is based on the presence or absence of a palpable pulse • Pulseless V tach • Immediate defibrillation
Ventricular Tachycardia • Treatment of V tach with a pulse is based on patient’s clinical picture • Hemodynamically unstable • (Low blood pressure, shortness of breath, etc.)Immediate cardioversion is considered • Hemodynamically stable • ( Normal blood pressure, absence of chest pain, and no notable change in mental status )Drug intervention is appropriate
Ventricular Tachycardia • Causes may include • Myocardial ischemia, hypoxia, electrolyte imbalances, increased anxiety or physical exertion, and underlying heart disease
Torsades De Pointes • Similar to ventricular tachycardia • Morphology of QRS complexes showsvariations in width and shape • Resembles aturning aboutor twisting motionalong base line • May result from • Hypokalemia, hypomagnesemia, tricyclic antidepressant drug overdose, use of antidysrhythmic drugs, or combination of these