A cardiac rhythmOften refers to a discernible pattern in time or distance between QRS complexes and/or P waves. characterized by occasional P wavesA wave generated from the depolarization of the atria; the P wave is upright when originating from the SA node. The P wave represents the depolarization of the right and left atria. The P wave begins with the first deviation... without a QRSThe electrical representation of ventricular depolarization; the atrial repolarization is also a part of the QRS. ECG interpretation relies heavily on the QRS complex. The QRS complex represents the depolarization of the ventricles. The repolarization of the atria is also... (lonely Ps) and a fixed PR intervalA period measured on rhythm strip paper that measures a wave and a segment; the distance measured is equal to time taken as an ECG is voltage over time; a PR interval for example is measured from the beginning of...; 1 lonely P wave may be present or consecutive lonely P waves – this is a serious rhythm with potential significant effects on cardiac outputWhat is it? Why is it Vital? The amount of blood pumped out of the ventricle in a minute (most often refers to the blood pumped by the left ventricle) What is cardiac output? Simply, cardiac output is the amount....
Atrioventricular blocksAtrioventricular blocks (AV blocks) result from a conduction disturbance at or just below the AV junction. The 3rd step of the 3 step process prompts us to check the P waves and the PR interval. Abnormal PR intervals and lonely... (AV blocks) result from a conduction disturbance at or just below the AV junctionConducts the impulse through the fibrous plate that separates the atria and the ventricles; consists of the AV node and the bundle of His; functions also to slow the conduction speed to allow for atrial conduction prior to ventricular conduction.... The 3rd step of the 3 step process prompts us to check the P waves and PatternPattern refers to the repeating components of an ECG rhythm in a predicative order. An ECG rhythm that is initiated by one of several intrinsic pacemaker sites of a heart will often generate a regular, even rhythm pattern. This can..., with particular attention to the PR interval. Abnormal PR intervalsThe time and interval measured from the beginning of the P wave to the beginning of the QRS; should be called the PQ interval; normal PR interval is 0.12-0.20 seconds. The PR interval is measured from the start of the... and lonely ‘P’ waves define the type of AV block.
From a clinical perspective, the severity of a block is similar to the severity of burns. The higher the degree of burn the more aggressive the treatment. Similar escalation in treatment is required for higher levels of AV blocks. The affects of 2nd degree type II and 3rd degree AV blocks on cardiac output can be much more significant than the affects of 2nd degree type I and 1st degree AV blocks.
Second Degree AV Blocks have lonely P waves with a PR interval that confirms an atrioventricular association. There are 3 varieties of 2nd degree AV block: 2nd degree AV block Type IA cardiac rhythm characterized by occasional P waves without a QRS (lonely Ps) and an observable pattern of progressive lengthening of the PR interval followed by a P wave without a QRS (dropped QRS) – the PR interval then shortens... (sometimes called WenckebachA physiologist of the late 19th and early 20th century, who is responsible for the discovery of the Second Degree AV Block Type I and Type II. Second Degree AV Block Type I Metaphorically, picture the junction as a gate....); 2nd degree AV block Type II (sometimes called MobitzA physiologist who in the 1920s discovered the 2nd degree AV heart blocks – Type I and Type II; note that the physiologist Wenckebach is reputed to accomplish similar discoveries 15-20 years earlier. 1. Six Second ECG Guidebook (2012), T Barill, p. 199 II); and a hybrid of the two called 2nd degree AV block 2:1 conduction.
Second Degree AV Block Type II is a significant dysrhythmiaUsed interchangeably with arrhythmia, refers to any abnormal rhythm – not normal sinus rhythm or sinus tachycardia. 1. Six Second ECG Guidebook (2012), T Barill, p. 196 due to 1) its unpredictability; 2) its potential to cause consecutive dropped QRS complexes and 3) its tendency to progress to a complete heart blockAlso known as complete heart block, the supraventricular impulse is blocked at the junction or high in the bundle branches; as a result, the myocardium above the block depolarizes independently of the myocardium below the block; characteristics of this rhythm... (third degree AV block). Second degree AV block is identified with lonely ‘P’ waves and a fixed PR interval. The metaphorical gate is either open or closed.
Second degree AV block Type II occurs at the level of the bundle branchesThe bundle of His terminates in the right and left bundle branches, insulated rapidly conducting electrical pathways that connect with the Purkinje network and thus begin depolarizing waves across the ventricles; the left bundle branch splits into three smaller branches... (common) or at the bundle of HisPart of the AV junction, the bundle of His conducts the impulse through the fibrous plate that separates the atria and the ventricle; the bundle of His is also a pacemaker, firing at 40-60/minute. The bundle of His serves as... (much less common). This dysrhythmia often has includes aberrant conductionFor about 15% of rhythms with wide QRS complexes, impaired bundle branch conductivity prolongs ventricular depolarization. Ischemia, infarction, and antiarrythmics can slow or block transmission of an impulse along these bundle branches. The resulting widening of the QRS complex is... through the ventriclesThe larger chambers of the heart (3 times the volume and muscle thickness than the atria), responsible for the pumping of blood to the lungs and the rest of the body. (bundle branch blockSince the bundle branches are insulated – they are encapsulated with a fibrous sheath – an obstacle to conduction in any bundle (i.e. ischemia or infarct) results in the impulse not carried through to the ventricle; as a result, the...). Causes of second degree AV block type II include cardiac ischemiaThe ability to identify cardiac ischemia, injury and infarction is vital in the management of the majority of cardiac emergencies. Most sudden cardiac deaths are associated with an ischemic episode. Patient deaths due to an acute myocardial infarction (MI) typically... and an anteroseptal myocardial infarctionWhen combined with congruent clinical findings, a diagnosis of an anteroseptal myocardial infarction (MI) is strongly supported. Since the anteroseptal region of the heart involves the left ventricle, it is prudent to continue the investigation into the lateral region that....
1. Six Second ECG GuidebookA Practice Guide to Basic and 12 Lead ECG Interpretation, written by Tracy Barill, 2012 Introduction The ability to correctly interpret an electrocardiogram (ECG), be it a simple six second strip or a 12 lead ECG, is a vital skill... (2012), T Barill, p. 125-127, 205