Chapter-12 Electrocardiography

BOOK TITLE: Manual of Clinical and Practical Medicine

1. Sainani GS
2. Sainani Rajesh G
Publishing Year
Author Affiliations
1. Grant Medical College and J.J.Hospital, Mumbai, Maharashtra, India, Endocrine and Diabetes Centre, Visakhapatnam, India, Jaslok Hospital and Research Centre, Mumbai; Armed Forces (for life); Chicago Medical School and Mount Sinai Hospital, Chicago, USA; 10 Other Foreign Universities & Several Indian Universities, CSI, Jaslok Hospital and Research Centre, Mumbai, Maharashtra, India, Jaslok Hospital and Research Centre, Mumbai, Maharashtra, India; National CSI, Jaslok Hospital & Research Centre, Mumbai, Maharashtra, India; Grant Medical College & JJ Hospital, Mumbai, Maharashtra, India; National Academy of Medical Sciences, New Delhi, India, Emeritus International Advisor, Royal College of Physicians, London; Chicago Medical School and Mount Sinai Hospital, Chicago, USA, Jaslok Hospital and Research Center; Grant Medical College and JJ Hospital, Mumbai, Maharashtra, India
2. Jaslok Hospital and Research Center, Mumbai, Maharashtra, India, Jaslok Hospital and Research Centre, Bhatia Hospital, Mumbai, Maharashtra, India, Royal Melbourne Hospital, Australia; Jaslok Hospital, Sir HN Reliance Foundation Hospital and Bhatia Hospital, Mumbai; GI Physiology & Motility Laboratory, Digestive Diseases and Endoscopy Centre, Motiben Dalvi Hospital, Mumbai, Maharashtra, India
Chapter keywords
Electrocardiogram, ECG, electrocardiography, acute myocardial infarction, AMI, ischemic heart disease, cardiac arrhythmia, electrolyte disturbance, digitalis toxicity


Electrocardiogram (ECG) is a graphic record of electrical activity of the heart. It is a useful tool for diagnosis of conditions, such as acute myocardial infarction (AMI), ischemic heart disease, cardiac arrhythmias, electrolyte disturbances and digitalis toxicity. For a beginner, pattern recognition is very useful. For thorough understanding, one has to learn spatial vectorial analysis. Conventional ECG is recorded at a paper speed of 25 mm/second. One small square (equal to 1 mm) measures 0.04 seconds while one big square (equal to 5 mm) measures to 0.2 seconds. Voltage is measured along vertical axis. This chapter covers the deflections, conduction system of heart, and 12 lead ECGs with interpretation. P wave is due to atrial depolarization. It is the sum of right and left atrial activations (early part of P wave represents right atrial electrical activity and terminal part represents left atrial activity). P wave is upright in most leads except aVR. It is best seen in leads II and VI.

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