10 Introducing the Ventricular Rhythms 1

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 their site 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 that patient assessment is the most important indicator of clinical significance

Components of Electrical Conduction System of the Heart

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 Single ectopic (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) The underlying cadence of SA node is not interrupted by a PVC nor is SA node depolarized PVC is usually followed by a compensatory pause Presence of compensatory pause, coupled with wide, bizarre, and premature QRS complex’s are highly suggestive indicators of PVCs

Compensatory Pause

Premature Ventricular Complexes (Contractions) (PVC) PVC may fall between two sinus beats without interfering with the rhythm Referred to as an interpolated 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

PVC Patterns of Occurrence

Premature Ventricular Complexes

Premature Ventricular Complexes - Unifocal

Premature Ventricular Complexes - Multifocal

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

Ventricular Bigeminy and Couplet PVCs

Ventricular Bigeminy

Ventricular Trigeminy

R on T

Idioventricular Rhythms Also termed ventricular 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 usually less than 40 bpm, and cardiac output is usually compromised

Agonal Rhythm Agonal rhythm is when the idioventricular rhythm falls below 20 bpm Frequently may be seen as the last-ordered semblance of a heart rhythm when either resuscitation is unsuccessful or after successful defibrillation

Idioventricular Rhythms Causes include extensive myocardial damage, secondary to acute myocardial infarction, or failure of higher pacemakers Is considered a lethal rhythm and treatment must be immediate and aggressive

Idioventricular Rhythms

Accelerated Idioventricular Rhythm May occur when the rate of the ectopic pacemaker exceeds 40 bpm Commonly accepted rate is 40-100 bpm There are no P waves or PR intervals noted

Accelerated Idioventricular Rhythm

Accelerated Idioventricular Rhythm May occur in conjunction with myocardial ischemia Can be mistaken for ventricular tachycardia Imperative that you remember to always assess and treat the patient, rather than the monitor or EKG strip

Ventricular Tachycardia Rhythms This rhythm is one in which three or more PVCs arise in sequence at a rate greater than 100 bpm This rhythm commonly overrides the normal pacemaker of the heart Often occurs rapidly and is initiated 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 for less than 30 seconds, it is a nonsustained rhythm,or simply a run of V tach

Ventricular Tachycardia

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

Ventricular Tachycardia Rhythm

Torsades De Pointes Similar to ventricular tachycardia Morphology of QRS complexes shows variations in width and shape Resembles a turning about or twisting motion along base line May result from Hypokalemia, hypomagnesemia, tricyclic antidepressant drug overdose, use of antidysrhythmic drugs, or combination of these

Torsades De Pointes

Torsades De Pointes Finding and treating the underlying cause of the rhythm is essential Magnesium is the pharmacologic treatment of choice Key to recognizing torsades is the variation of QRS morphology, or shape

Ventricular Fibrillation Is a fatal dysrhythmia Is the most frequent initial rhythm occurrence in sudden cardiac arrest Tends to occur in the initial hours following an acute myocardial infarction Occurs as a result of multiple weak ectopic foci in the ventricles

Ventricular Fibrillation Myocardial cells appear to quiver rather than depolarize normally No coordinated atrial or ventricular contraction, and no palpable pulse Electrical impulses initiated by multiple ventricular sites; impulses are not transmitted through normal conduction pathway

Ventricular Fibrillation Waveforms appear as disorganized, rapid, irregular waves whose morphology varies vastly No well-organized QRS complexes Death will occur if immediate treatment is not established

Ventricular Fibrillation Classified as either Fine ventricular fibrillation Ventricular fibrillation waves less than 3 mm of amplitude Coarse ventricular fibrillation Ventricular fibrillation waves with amplitudes greater than 3 mm Course fib is generally more irregular than fine fib

Ventricular Fibrillation Patient assessment is critical in that artifact, or loose leads can resemble ventricular fibrillation Treat the patient… not the monitor Causes include Acute MI, myocardial ischemia, drug toxicity or overdose, hypoxia, and other causes

Ventricular Fibrillation

Ventricular Fibrillation (Fine)

Ventricular Fibrillation (Coarse)

Ventricular Asystole The absence of all ventricular activity Also called cardiac standstill or asystole Asystole is represented by a flat line, and is the absence of all cardiac electrical activity

Ventricular Asystole It may be difficult to distinguish asystole from fine VF; you must always check two different leads to definitively identify asystole Often follows unsuccessful resuscitation attempts May be caused by Massive MI, cardiac trauma, ventricular aneurysm, and complete heart blocks

Ventricular Asystole

Ventricular Asystole (Cardiac Standstill, Asystole)

Pulseless Electrical Activity The absence of a palpable pulse and myocardial muscle activity with presence of organized electrical activity on the cardiac monitor Represents a clinical condition, the patient is clinically dead despite some type of organized rhythm on monitor

Pulseless Electrical Activity Formerly termed electromechanical dissociation, or EMD Causes include Profound hypovolemia, massive myocardial damage, ventricular rupture, pulmonary embolism, acidosis, cardiac tamponade, hypothermia, hyperthermia, drug overdose, hypokalemia, hyperkalemia, or tension pneumothorax

Clinical Significance of Ventricular Dysrhythmias Premature ventricular complexes Little or no significance in patient’s without history of heart disease May even relate that their caffeine or stress have increased the “palpitations” Cardiac output may be compromised if PVCs are frequent Administration of oxygen may abate the PVCs

Idioventricular Rhythm Majority are symptomatic Due to decreased heart rate, may develop decreased cardiac output, weakness, dizziness, hypotension, and alterations in mental status A thorough patient assessment is conducted to determine whether rhythm is perfusing

Clinical Significance of Ventricular Tachycardia May be perfusing (producing a palpable pulse) or nonperfusing (producing no palpable pulse) Due to rapid heart rate, ventricles do not have time to empty and refill = cardiac output compromised Treatment is based on the absence or presence of a palpable pulse as well as the patient’s clinical picture

Clinical Significance of Ventricular Dysrhythmias If V tach is perfusing and stable Treatment consists of oxygen administration, IV lifeline, and pharmacologic intervention If V tach patient becomes clinically unstable (as evidenced by hypotension, SOB, and CP) Synchronized cardioversion is indicated

Clinical Significance of Ventricular Fibrillation There is no cardiac output, no perfusion If not treated immediately, patient will not sustain life The presence of fine V fib Indicates rhythm has been present for extended period of time

Clinical Significance of Ventricular Fibrillation Treatment includes CPR, defibrillation (360 J, one shock using monophasic or equivalent biphasic wave forms), airway control, IV lifeline, and drug intervention

Clinical Significance of Asystole Signals a complete termination of ventricular activity Check in two leads to rule out the presence of fine V fib Treatment includes CPR, IV lifelines, endotracheal intubation, and pharmacologic intervention

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