Skip to main content

ECG 3-Normal Sinus Rhythm (NSR)


•    Etiology: the electrical impulse is formed in the SA node and conducted normally.

•    This is the normal rhythm of the heart; other rhythms that do not conduct via the typical pathway are called arrhythmias.


NSR Parameters
•    Rate                60 - 100 bpm    
•    Regularity            regular
•    P waves            normal
•    PR interval            0.12 - 0.20 s
•    QRS duration        0.04 - 0.12 s
Any deviation from above is sinus tachycardia, sinus bradycardia or an arrhythmia



Arrhythmia Formation
Arrhythmias can arise from problems in the:
•    Sinus node
•    Atrial cells
•    AV junction
•    Ventricular cells


SA Node Problems
The SA Node can:
fire too slow--- Sinus Bradycardia

fire too fast--- Sinus Tachycardia




Atrial Cell Problems
Atrial cells can:

•    fire occasionally from a focus ---Premature Atrial Contractions (PACs)

•    fire continuously due to a looping re-entrant circuit ----Atrial Flutter 



Atrial Cell Problems
Atrial cells can also:
• fire continuously from multiple foci Atrial Fibrillation

or
fire continuously due to multiple micro re-entrant “wavelets” Atrial Fibrillation




AV Junctional Problems
The AV junction can:

•    fire continuously due to a looping re-entrant circuit--Paroxysmal   Supraventricular Tachycardia
•    block impulses coming from the SA Node--AV Junctional Blocks



Ventricular Cell Problems
Ventricular cells can:
•    fire occasionally from 1 or more foci --Premature Ventricular Contractions (PVCs)
•    fire continuously from multiple foci--Ventricular Fibrillation
•    fire continuously due to a looping re-entrant circuit--Ventricular Tachycardia

Popular posts from this blog

Gray’s Anatomy 40th Edition free Download

Gray’s Anatomy: The Anatomical Basis of Clinical Practice, Expert Consult – Online and Print, 40 Ed Churchill Livingstone | 2008 | ISBN: 0443066841 | 1576 pages | CHM | 75 MB Meticulously enhanced and updated artwork throughout – with 2,000 images now in full color – provide a more consistent, coherent view of every anatomical detail, providing practitioners across all specialties with the best, most clinically helpful visual understanding available. * 200 completely new radiologic, CT, MR, and other imaging studies vividly capture anatomy as it is primarily seen by physicians. Gray’s Anatomy is the most Handy book of medical students who are engaged in anatomy trouble. Anatomy is really a tough subject and without proper reference book, all is in vein. So download it as soon as you can http://www.6ybh-upload.com/q4p8gwmi10qg/Gray's_Anatomy_40th_Edition.rar Find Us O Facebook -  http://www.facebook.com/med.saisayan

MICROBIOLOGY LECTURES

TO DOWNLOAD A LECTURE CLICK ON X mark AGAINST THE TOPIC Lecture PPT Introduction to MMID X Intro I: virus structure and classification X Intro II: laboratory virology X Intro III: pathogenesis & genetics X DNA viruses I: papillomaviruses X DNA viruses II: adeno, parvo and polyomaviruses X (-) RNA viruses I: influenza virus X (-) RNA viruses II: measles, mumps, parainfluenza and respiratory syncytial viruses X (-) RNA viruses III: rhabdovirus (rabies) and reoviruses (rotavirus, diarrhea) X (+) RNA viruses I: ente...

PHARMACOLOGY POWERPOINT PRSENTATIONS

Acute Poisoning Antiplatelet & Anticoagulant drugs Antihypertensive treatment Common Poisonings Drug Development Course Introduction Investigation of Secondary Hypertension Pharmacokinetics & Therapeutic Drug Monitoring Prescribing I Prescribing II Revision Lecture (Phase III) - Seminar handouts and slides Treatment of Anaphylaxis Treatment Algorithms for Anaphylaxis Treatment of Asthma & COPD Treatment of Diabetes Mellitus Treatment of Hyperlipidemias Ischaemic heart disease Heart failure / Dyslipidaemias Dysrhythmias Respiratory pharmacology Gastro-intestinal / liver Introduction to prescribing Neuro-pharmacology Endocrine / Diabetes Analgesics / Anti-inflammatories Rena...