9When placing the precordial chest leads across the thorax, the clinician places the electrodes under the pectoralis major & not over the breasts.
10In The Chest Cavity, The Heart Is Positioned With The Right Ventricle Lying Anteriorly & Medially While The Left Ventricle Lies Anterolaterally & Posteriorly
11Therefore, Leads V1 & V2 Lie Directly Over The Right Ventricle Therefore, Leads V1 & V2 Lie Directly Over The Right Ventricle. Their Line Of Sight Is To View The Electrical Activity Coming From The Right Ventricle.
12Leads V3 & V4 Lie Directly Over The Interventricular Septum Leads V3 & V4 Lie Directly Over The Interventricular Septum. Their Line Of Sight Is To View The Electrical Activity Of The Interventricular Septum.
41The PR Interval Represents The Time Period Encompassing Atrial Depolarization Up To But Not Including The Start Of Ventricular Depolarization.
42“A major portion of the PR interval reflects the slow conduction through the AV node which is controlled by the sympathetic-parasympathetic balance within the autonomic nervous system”.Marriott’s Practical Electrocardiography, 9th ed., Galen S. Wagner, pg 39, 1994
43Duration : The Adult PR Interval Is Normally Between 3-5 mm Or. 12 - Duration : The Adult PR Interval Is Normally Between 3-5 mm Or Seconds In Duration. Some Cardiologists Will Say It Is Normal Out To .22 Seconds (5 1/2 mm)
44If The PR Interval Is Longer Than 5 mm, It Is Called A Prolonged PR Interval & May Indicate The Presence Of An AV Block.
46The PR Interval Shortens During Exercise Because Of The Sympathetic Tone That Predominates Over The Heart.
47If The PR Interval Could Not Shorten, Along With Other Segments In The EKG, Then Acceleration Of Heart Rate During Exercise Would Be Difficult If Not Impossible.
48In Young Children, The PR Interval Is Shorter Than In Adults In Young Children, The PR Interval Is Shorter Than In Adults. The Child’s Heart Rate Is Also Faster.
49In A 1 Year Old Child At Rest, The Normal P-R Interval Is Typically In A 1 Year Old Child At Rest, The Normal P-R Interval Is Typically .11 sec. Or Slightly Under 3 mm.
50For Children Who Are 6 Years Of Age, The P-R Interval At Rest Is For Children Who Are 6 Years Of Age, The P-R Interval At Rest Is .13 Seconds Or Slightly Over 3 mm.
51In Children 12 Years Of Age, The P-R Interval At Rest Will Be In Children 12 Years Of Age, The P-R Interval At Rest Will Be .14 Seconds Or About 3.5 mm.
52In Grown Adults 18 Years Of Age And Older, The P-R Interval At Rest Will Be 3-5 mm In Length.
53Prolonged P-R Intervals Are Symptomatic Of : AV Blocks Due To Coronary Disease & Rheumatic Fever.
54Sometimes, Prolonged P-R Intervals Not Related To Heart Disease, Can Be Seen In Healthy Athletes - An Aberration Called A Normal Variant. This Can Be Seen In About ~ 1% - 2% Of The Healthy, Young Population.
56Shortened P-R Intervals Are Seen In Patients With Pheochromocytoma And Wolfe-Parkinson-White Syndrome
57Pheochromocytoma is a tumor in the adrenal medulla that results in a greater-than-normal release of catecholamines. The high blood concentration of catecholamines causes the heart rate to accelerate.
58Wolff-Parkinson-White Syndrome is a medical condition in which atrioventricular myocardial accessory pathways electrically pre-excite the ventricles to contract producing an extremely short PR interval.
59These accessory electrical pathways are remnants of fetal pathways that did not disappear after birth. The Bundle Of Kent has been implicated as a common aberrant pathway in W-P-W.
60W-P-W occurs in ~. 15% -. 20% of the population or 2:1,000 people W-P-W occurs in ~ .15% - .20% of the population or 2:1,000 people. Patients with W-P-W are otherwise healthy.
61W-P-W effects men more than women and can evolve into atrial and ventricular dysrhythmias with a general mortality up to 4% of the effected population.
62Patients with W-P-W often complain of episodic symptoms that include chest discomfort, dizziness, and palpitations.
105So...., The Classic Signs Of An Acute MI In Progress Are : Elevated ST SegmentInverted T WavePresence Of A Q Wave
106Anterior Wall Infarction Signs Of AnAnterior Wall Infarction
107Anterior Wall Infarction An anterior wall MI is usually caused by an occlusion of the LADEKG changes are seen in any of the precordial chest leads - V1 - V6
108ST Segment Changes With An Acute Anterior MI ST segment elevation in V1-V6 and in Leads I and aVL (the lateral wall leads).Reciprocal ST segment depression in Leads II, III & aVF (the inferior leads)
129ST Segment Depression May Be A Permanent Part Of The EKG Tracing.
130At Rest The Patient May Have A Normal ST Segment At Rest The Patient May Have A Normal ST Segment. However, It May Become Depressed As The Person’s Exercise Level Is Increased Above The Heart’s Ability To Receive Adequate Perfusion.
131The ST segment depression will begin to appear as the heart becomes ischemic It will continue to be more depressed the more ischemic the heart becomes.
132The ST segment will normalize once the exercise intensity is reduced to a level in which the heart receives enough perfusion to support the work that is being demanded.
133The T Wave The T Wave Represents Repolarization Of The Ventricles. Repolarization Proceeds From The Apex Of The Heart To The Base Of The Heart.
134In Normal Hearts, The T Wave Is Usually Upright In Leads I, II, III, aVF, aVL, & V2-V6.
135In Normal Hearts, The T Wave Will Usually Be Upside Down In aVR And V1.
136The Normal Duration Of The T Wave Is About 1-2 mm.
137Normal Amplitude For The T Wave Is Highly Variable.