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A detailed explanation of various cardiac rhythms, including normal sinus rhythm, sinus bradycardia, sinus tachycardia, premature atrial contractions (pacs), paroxysmal supraventricular tachycardia (psvt), and atrial flutter. It includes definitions, ecg characteristics, clinical associations, clinical significance, and treatment options for each rhythm. Designed to help students understand the fundamentals of dysrhythmias and their management.
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dysrhythmia aka arrhythmia - Correct answer - abnormal cardiac rhythms which can cause disturbances of: rate, rhythm, or both rate and rhythm how are dysrhythmias identified? - Correct answer Electrographic Waveform Analysis (ECG) what controls the rate and rhythm of the heartbeat? - Correct answer the heart's electrical system explain the heart's electrical system - Correct answer Each electrical signal (impulse) begins in a group of cells called the sinus node or sinoatrial (SA) node. The SA node is located in the right atrium. In a healthy adult heart at rest, the SA node sends an electrical signal to begin a new heartbeat 60 to 100 times a minute. (This rate may be slower in very fit athletes.) From the SA node, the electrical signal travels through the right and left atria. It causes the atria to contract and pump blood into the ventricles. The electrical signal then moves down to a group of cells called the atrioventricular (AV) node, located between the atria and the ventricles. Here, the signal slows down slightly, allowing the ventricles time to finish filling with blood. The electrical signal then leaves the AV node and travels to the ventricles. It causes the ventricles to contract and pump blood to the lungs and the rest of the body. The ventricles then relax, and the heartbeat process starts all over again in the SA node. normal sinus rhythm (characteristics) - Correct answer 1. Rate:60-100 beats/min Rhythm: regular
Rhythm: regular
-HR varies with underlying rate and frequencies of the PAC, and the rhythm is irregular. P wave has a different shape from the P wave that originates from SA node, or it may be hidden in the preceding T wave. PR interval may be shorter or longer but its within normal limits. QRS is usually normal. If the QRS is .12 sec or more, abnormal conduction through the ventricles occurs
ectopic focus - Correct answer pacemaker location other the SA node vagal stimulation - Correct answer response caused by stimulation of right vagus nerve. After transmission excitation of the Parasympathetic ganglia ACh is released in the SA node which causes slowing or stopping of the heart. -rate of depolarization is decreased vagal maneuvers: -Valsalva maneuver -carotid massage -coughing ganglia - Correct answer An anatomically distinct collection of sensory or motor neuron cell bodies within the Peripheral NS vagus nerve - Correct answer 10th cranial nerve -interfaces with autonomic parasympathetic control of the heart and the GI tract PSVT - Correct answer -dysrhythmia starting at in ectopic focus anywhere above the bifurcation of the bundle of His -In PSVT, abnormal conduction of that electricity causes the atrium, and secondarily the ventricles, to beat very rapidly. -It is referred to as paroxysmal, because the rapid rate can occur sporadically and without warning and may also stop on its own -The rapid heartbeat may last a few seconds or many hours. Often the PSVT resolves before the patient reaches a health care professional. -In many patients with PSVT, there is a "wiring" problem in the AV node and instead of having just one pathway for electricity to travel to the ventricle, there are two. This allows electricity to circle back and cause the atrium to beat more quickly than it should normally. -PSVT is one of many electrical abnormalities that cause the atrium to beat too quickly. -termination may result in systole for a brief period PSVT: clinical associations - Correct answer --> in normal heart PSVT is associated with: overexertion emotional stress deep inspiration and stimulants --> also associated with rheumatic heart disease, digitalis toxicity, CAD and or cor pulmonale
-in AFL, the atria (upper chambers) of the heart beat too fast, which results in atrial muscle contractions that are faster than and out of sync with the lower chambers (ventricles) -the impulse travels in the atria in an organized circular motion or "circuit" in the atria, causing the atria to beat faster than the ventricles -AV node can delay signals to ventricles, so there is usually some AV blocks in a fixed ratio of flutter waves to QRS complexes Atrial Flutter clinical associations - Correct answer -->rarely occurs in a healthy heart associated with: CAD, HTN, mitral valve disorders, pulmonary embolus, chorine lung disease, hyperthyroidism, cardiomyopathy, corpulmonale, and use of drugs such as digoxin, quinidine, and epinephrine Atrial Flutter characteristics - Correct answer -atrial rate is 200- 350. -ventricular rate is based on conduction ratio. --> In 2:1 conduction, the ventricular rate is typically ~ 150. -Atrial rhythm is regular, and ventricular rhythm is usually regular. -The atrial flutter waves represent atrial depolarization followed by repolarization. -The PR interval is variable and not measurable. The QRS complex is usually normal. -Bc the AV node can delay signals from the atria, there is usually some AV block in a fixed ratio of flutter waves to QRS complexes. supraventricular - Correct answer means above the ventricles so afib and a flutter are these as well Atrial Flutter vs Atrial Fibrillation - Correct answer similar but -in AFib, the heart beats fast and in no regular pattern or rhythm. -with AFL, the heart beats fast, but in a regular pattern. The fast but regular pattern of AFL is what makes it special. makes a very distance sawtooth pattern on ECG -at times, atrial flutter and Afib may coesxit -both include reentry of the impulse in the atria but atrial flutter is a systematic circuit and Afib is a chaotic reentry pathway
reentry rhythm - Correct answer Re-entrant arrhythmias occur when an electrical impulse recurrently travels in a tight circle within the heart, rather than moving from one end of the heart to the other and then stopping classifying arrhythmias - Correct answer -by rate (normal sinus rhythm, tachycardia, bradycardia) or mechanism (automaticity, reentry, junctional, fibrillation) -During an arrhythmia, the heart can beat too fast, too slow, or with an irregular rhythm. what is atrial flutter caused by? - Correct answer -caused by a reentrant rhythm in either the right or left atrium. -For each cycle around the loop, there results an electric impulse that propagates through the atria. Atrial Flutter clinical significance - Correct answer the higher ventricular rates (>100) and loss of atrial "kick" (contraction) that are associated with AFL decreases CO (cardiac output) -this can cause serious consequences such as HF -patients with AFL have an increased risk of stroke bc of the risk or thrombus formation in the atria from the stasis blood -warfarin is given to prevent stroke in patients with AFL cardiac output - Correct answer (mL blood/min) -The volume of blood the heart (ventricles) pump through the circulatory system in a minute. -The amount of blood put out by the LEFT VENTRICLE of the heart in one contraction is called the STROKE VOLUME. -The stroke volume and the heart rate determine the cardiac output. A normal adult has a cardiac output of 4.7 liters (5 quarts) of blood per minute. CO= stroke volume X HR Since the heart is a 'demand pump', that pumps out whatever blood comes back into it from the venous system, it is effectively the amount of blood returning to the heart that determines how much blood the heart pumps out (CO). Atrial Flutter Treatment - Correct answer primary goal: slow the ventricular response by increasing AV block. -drugs used to control ventricular rate include: calcium channel blockers and Beta-adrenergic blockers
pericarditis --> often develops acutely with thyrotoxicosis, alcohol intoxication, caffeine use, electrolyte imbalance, stress, cardiac surgery AFIB: ECG characteristics - Correct answer -during fibrillation, atrial rate may be as high as 350-600 beats/min -P waves are replaced by chaotic fibrillary (f) waves -ventricular rate varies and the rhythm is usually irregular -when ventricular rate is between 60-100 it is atrial fibrillation with a "controlled ventricular response" -atrial fibrillation with ventricular rate >100 is AFib with a "rapid (or uncontrolled, ) ventricular response. -The PR interval is not measurable A) Rate/Rhythm: Atrial: 350-600 / Regular Ventricular: > or < 100 / may be regular or irregular B) P wave : Fibrillatory (f) waves C) PR interval: not measurable D) QRS complex: normal (usually ) Afib (AHA) - Correct answer -multiple ectopic foci -may be paroxysmal (beginning and ending spontaneously, or persistent ( >7 days) -in Afib the atria beat irregularly (quiver) instead of beating effectively to move blood into the ventricles -In AF, the normal regular electrical impulses generated by the sinoatrial node in the right atrium of the heart are overwhelmed by disorganized electrical impulses usually originating in the roots of the pulmonary veins (left atrium), ectopic foci -This leads to irregular conduction of ventricular impulses that generate the heartbeat. AF may occur in episodes lasting from minutes to days (paroxysmal AF) or may be permanent in nature (persistent). -Many medical conditions increase the risk of AF, in particular mitral stenosis (narrowing of the mitral valve of the heart). --> -In AF, the heart's electrical signals don't begin in the SA node. Instead, they begin in another part of the atria or in the nearby pulmonary veins. The signals don't travel normally. They may spread throughout the atria in a rapid, disorganized way. This can cause the atria to fibrillate. Signal re circulates through atrium but in a chaotic path
-The faulty signals flood the AV node with electrical impulses. As a result, the ventricles also begin to beat very fast. However, the AV node can't send the signals to the ventricles as fast as they arrive. So, even though the ventricles are beating faster than normal, they aren't beating as fast as the atria. [controlled or uncontrolled ventricular response ] -controlled ventricular response: ventricular contraction is 60-100 /min -uncontrolled ventricular response: ventricles contract more than 100 beats/ min -Thus, the atria and ventricles no longer beat in a coordinated way. This creates a fast and irregular heart rhythm. when does Afib occur? - Correct answer AF occurs if rapid, disorganized electrical signals cause the heart's two upper chambers—called the atria- to fibrillate fibrillate - Correct answer The term "fibrillate" means to contract very fast and irregularly Atrial Fibrillation: Clinical significance - Correct answer Fib results in a decrease in CO bc of ineffective atrial contractions (loss of atrial kick) and/or a rapid ventricular response. -Thrombi (clots) form in the atria bc of blood stasis. an emboli zed clot may develop and move to the brain, causing a stroke. -Afib accounts for as many as 17% of all strokes Afib: treatment - Correct answer -->goals:
-these dysrhythmias are treated according to the pts tolerance of the rhythm and the pts clinical condition Junctional Dysrhythmias: Clinical association - Correct answer associated with: CAD HR Cardiomyopathy electrolyte imbalance inferior MI rheumatic heart disease
-accelerated junctional rhythm/ junctional tachycardia caused by drug toxicity, the drug is stopped. In absence of digitalis toxicity, B Blockers, Ca channel blockers, and amiodarone are used for rate control. Cardioversion should NOT be used First degree AV block - Correct answer every impulse is conducted to the ventricles but the time of AV conduction is prolonged (This causes the prolonged PR interval). -After impulse moves through AV node, the ventricles usually respond normally. First degree AV block: clinical associations - Correct answer MI CAD rheumatic fever hyperthyroidism electrolyte imbalance vagal stimulation drugs (ex: digoxin, Bblockers, Ca channel blockers) First degree AV block: clinical significance - Correct answer -not usually serious but can be a sign of higher degrees of AV block. -pts are Asymptomatic -no treatment First degree AV block: ECG - Correct answer PR prolonged (>.20) bc of prolonged conduction of AV node Second degree AV block - Correct answer type 1: Mobitz or Wenkeback heart block (SVT) and type 2: Mobits II heart block third degree AV block - Correct answer complete heart block -no impulses from atria are conducted to the ventricles
-treatment: atropine to increase HR, temporary pacemaker nonconductive - Correct answer not able to conduct heat or electricity or sound Second Degree AV block type I (Mobitz II) - Correct answer -almost always a disease of the distal conduction system (His-Purkinje System). -characterized on a surface ECG by intermittently nonconducted P waves not preceded by PR prolongation and not followed by PR shortening Secondary AV block type II - Correct answer -P wave is non conducted w/o progressive PR lengthening. This usually occurs in a block in one of the bundle branches is present -PR interval normal or prolonged but fixed
-rhythm irregular or regular -AV dissociation may be present, with P waves occurring independently of QRS complex -atria may be polarized in a retrograde fashion by ventricles -P wave usually buried in QRS complex -PR not measurable -QRS distorted and wide (>.12) -T wave in opposite direction of QRS complex Forms of VT - Correct answer -depend on QRS configuration
-AV dissociation may be present, with p waves occurring independently of the QRS complex -The atria may be depolarized by the ventricles in retrograde fashion -the P wave is usually buried in the QRS complex -PR interval is not measurable -QRS complex is distorted in appearance and wide (>.12) -T wave is in the opposite direction of the QRS complex VT: ECG Chart - Correct answer A) Heart Rate: 150- B) Rhythm: regular or irregular C) P wave: not visible D) PR interval: not measurable E) QRS complex: wide and distorted Ventricular Fibrillation (VF) - Correct answer -->condition in which there is uncoordinated contraction of the cardiac muscle of the ventricles in the heart, making them quiver rather than contract properly -a severe derangement of the heart rhythm characterized on ECG by irregular waveforms of varying shapes and amplitudes. -This represents the firing of multiple ectopic foci in the ventricle. -mechanically the ventricle is simply "quivering", with no effective contraction, and consequently no CO occurs. -VF is lethal