Regular rhythms can almost always be quickly identified with just steps #2 (Is the QRS narrow or wide?) and #3 (Check the 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... 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...). Simple, basic and fast. These rhythms would include sinus rhythms, atrial rhythms, junctional rhythmsA cardiac rhythm that occurs as a backup pacemaker when the sinus node fails to initiate an impulse; the junction typically fires at 40-60/minute; the P wave is either absent or inverted. A cardiac rhythm is usually named first by... and ventricular rhythms of varying rates. The irregular rhythms – those with pauses, extra beats, or which have a chaotic pattern – often demand closer inspection.
Checking for a regular rhythm patternAn 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 also be referred to as a regularly regular rhythm. For regular rhythms, sometimes the... simply involves determining whether the R-R intervalThe distance between the top of the R waves. Figure 4.15 The Normal Q Wave and QT Interval Figure 4.15 illustrates the Q wave, QT interval and the R-R interval. A normal QT interval should be less than half the... is consistent. This often can be accomplished with a quick visual snapshot of the rhythmOften refers to a discernible pattern in time or distance between QRS complexes and/or P waves.. Are the QRS complexes evenly spaced?
P wave
A P wave typically precedes each QRS complexThe 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.... A P wave represents the electrical wave crossing the atrial myocardiumThe muscle layer of the heart; the middle layer that is responsible for contraction of the heart. The muscular myocardium is the thickest layer and the workhorse of the heart. It is composed of specialized muscle and electrical cells that.... While a P wave can come in many shapes, most common are upright P waves indicative of sinus rhythms.
– Upright P wave – sinus origin
– Inverted or absent P wave – junctionConnects the atria to the ventricle and slows the impulse conduction speed sufficiently to allow for atrial kick; the junction consists of the AV node and the bundle of His; the junction is a supraventricular structure. 1. Six Second ECG... origin
– biphasic or changed P wave from normal – atrial origin
When identifying (naming) a rhythm, the first word in the name locates the origin of the electrical impulse. Since the majority of all rhythms originate above 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. (supraventricularLocated above the ventricle – includes the bundle of His, AV node, atria and the SA node. 1. Six Second ECG Guidebook (2012), T Barill, p. 206), the shape of the P wave matters.
Normal P wave criteria: upright in leads I, II and aVF, and biphasic (parts up and down facing) in lead V1. Height is less than 2.5 mm (.25 mVmilliVolt; the ECG is usually calibrated to display 1mV = 10mm of amplitude. 1. Six Second ECG Guidebook (2012), T Barill, p. 200). Width of the P wave should be less than .12 seconds. A normal P wave suggests a sinus node site of electrical impulse initiation.
Abnormal P waveA normal wave is typically upright in leads I, II and aVF, and biphasic in lead V1. An abnormal P wave can possess several alternate characteristics including a misshapen P wave (bifid shape), a P wave lasting longer than 115...: when the P wave is larger – higher than 2.5 mm in lead II – atrial enlargementAtrial enlargement and dilation can be caused by tricuspid and bicuspid (mitral) valve disease, hypertension, and ventricular hypertrophy among other causes. A P wave can change with atrial enlargement to be taller than 2.5 mm in leads I, II and... is a possibility. A 2-hump (bifid) P wave also speaks to atrial enlargement.
PR IntervalThe 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...
The 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... that begins with the beginning of the P wave and ends with the beginning of the QRS complexA collection of waveforms (i.e. QRS complex and the ECG complex). 1. Six Second ECG Guidebook (2012), T Barill, p. 194 is called the PR interval (PRI). The interval includes the time taken for the electrical wave to cross the atriaRight and left atria (1/3 volume and muscle mass of the ventricles) pump blood to the ventricles. Chambers and Layers of the Heart 1. Six Second ECG Guidebook (2012), T Barill, p. 190 (atrial depolarizationThe rapid influx of positive ions (sodium and/or calcium) into a cell – depolarization is necessary for contraction to occur. A depolarizing wave moves through the myocardium on average along a trajectory or vector. A vector is a force moving...) AND the time taken to cross the junction (AV nodeIs located in the inferior aspect of the right atria; functions to slow the conduction speed to allow for atrial conduction prior to ventricular conduction (atrial kick); also serves as a pacemaker if the SA node fails to fire. The... and 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...).
Normal PR Interval: a normal PR interval is .12-.20 seconds (3-5 mm).
Abnormal PR Interval: a PR Interval of more than .20 seconds is called 1st degree AV block. This can be a normal finding. A prolonged PR interval can point to nodalCommonly refers to the junction; for example, junctional rhythm is also known as nodal rhythm; may also refer to the sinoatrial node. 1. Six Second ECG Guidebook (2012), T Barill, p. 200 conduction slowing from medications (beta blockers, calcium channel blockers, and digoxin) or electrolyte imbalance (hyperkalemiaBlood potassium level higher than normal limits. Table 6.5 Normal and Abnormal Characteristics of ECG Waveforms Table 6.5 provides a non-exhaustive list of cardiac conditions that are associated with a variety of abnormal ECG waveforms. Arriving at a useful interpretation...). A short PR intervalA PR interval shorter than normal (less than 0.12 seconds) occurs commonly with junctional rhythms (the impulse begins somewhere in the AV junction) because part of the conduction pathway - the atria and part of the AV junction - is... can occur with preexcitation syndromes and with junctional rhythms.
Pattern
The pattern of components of an ECGElectrocardiogram; also called an EKG; a representation of electrical voltage measured across the chest over a period of time. 1. Six Second ECG Guidebook (2012), T Barill, p. 196 can offer considerable meaning. IntrinsicCharacteristic or property natural to the heart and its structures. 1. Six Second ECG Guidebook (2012), T Barill, p. 198 pacemakers such as the sinus node, AV node, bundle of His and Purkinje networkA matrix of fibres located throughout the myocardium that connects the impulse from the bundle branches to the myocardial tissue. The bundle branches and the Purkinje network facilitate rapid depolarization throughout the ventricles. The Purkinje network also creates a typical... all can produce a rhythm. The pattern of their impulse firing is typically regular.
Occasionally a node fires less than completely regular but a pattern remains. For example, a sinus arrhythmiaA cardiac rhythm that originates from the SA node without the usual regular rhythm indicative of sinus rhythm; this rhythm is common for children and for elderly adults; it presents as a narrowing of the R-R interval during inspiration and... is present when the sinus node speeds up and slows down over succesive beats i.e. increasing rateHeart Rate; calculated by counting the number of QRS complexes in six seconds and multiplying by 10; rate is also determined by measuring the number of large squares between two R waves; i.e. –1 large square = heart rate of 300/minute. followed by a decreasing rate. A common connection is increasing HR with inspiration and decreasing HR with expiration. This is more likely with the very young and the elderly.
When the rhythm pattern is off in some way, a closer look is always advisable. For example, a rhythm without any pattern – complete chaos – speaks to a fibrillation. Chaotic pattern with QRS complexes is atrial fibrillationOne of the most common dysrhythmias, the atria have a host of sites that are concurrently firing at a combined rate of 350-600/minute; since the junction allows maximum 240 impulses through per minute, the result is a chaotic rhythm most... in high probability. Chaotic pattern without recognizable QRS complexes point to the lethal rhythm ventricular fibrillationA chaotic unorganized cardiac rhythm with several firing regions within the ventricles; the result is uncoordinated ventricular activity and NO cardiac output – a lethal dysrhythmia; fine ventricular fibrillation defines an amplitude less than 3 mm; coarse ventricular fibrillation has....
As well, occasional early beats are likely premature atrial, junctional or ventricular complexes – PACEarly QRS complexes (usually narrow) make the ECG rhythm pattern irregular. Atrial impulses are preceded by abnormal P waves, often biphasic, but always distinct from the P waves generated by a sinus node. Premature atrial complexes (PAC) are typically benign,..., PJCA narrow QRS complex that arrives distinctly earlier than expected can be a premature atrial complex or a premature junctional complex (PJC). A PJC can be preceded by an inverted P wave, no P wave (timing places the inverted P..., PVCA wide QRS complex that arrives early is called a premature ventricular complex (PVC). A PVC has a width of 0.12 seconds or longer. The elongated period of ventricular depolarization is caused by an abnormal, less efficient pathway of ventricular.... Lonely P waves – P waves without associated QRS complexes after – are typical of second and thrid degree AV blocks. Pauses in QRS complexes can point to disease of the sinus node.