how does hear conduct impulse
The heart contracts and relaxes in response to electrical stimulation that originates in the sinoatrial (SA) node, the hearts pacemaker.
The impulse passes through the heart as a progressive wave if stimulation via conduction tracts through the right and left atria to the atrioventricular (AV) node where there is a pause allowing the ventricles to fill. The impulse then passes through the bundle of His and down the right and left bundle branches, carrying the electrical impulse to the right and left ventricles.
The Purkinje fibres, located at the end of each bundle branch transmit the impulse throughout each ventricle, causing them to contract.
The spread of electricity creates an electrical field around the heart.
what is ECG
An ECG or electrocardiogram is a graphical representation of the electrical impulses generated by the heart during the cardiac cycle.
what does ECG shows
It shows 2 basic electrical processes:
Depolarisation (the spread of electrical stimulus through the heart muscle) producing the P wave from the atria and the QRS from the ventricles.
Repolarisation (the return of the stimulated muscle to the resting state) producing the T wave.
The electrical impulses are conducted to the body’s surface, where they are detected by electrodes placed on the limbs and chest
The electrodes carry the electrical impulses to a continuously running graph that plots the ECG wave pattern
The appearance of the ECG wave pattern helps diagnose any abnormalities in electrical conduction through the heart
The 12 lead ECG shows 12 different views of the heart. The location of pathologic change within the heart, which alters the electrical activity can usually be pinpointed with the use of an ECG
what does P wave, PR interval, QRS complex, ST segment, T wave, U wave and QT interval mean?
under what circumstances you need to take ECG
Chest pain – typical or atypical
Heart rate/rhythm determination
Effect of medications (especially cardiac)
Effects of systemic disease of the heart (renal, pulmonary etc)
Effects of electrolyte imbalances
what do you need before conduct ECG
Identify anxiety level
Educate as required
Assure the patient about the safety of the procedure
Prepare the patient for the procedure.
Remove clothing to expose only chest and arms
Place patient in supine position
Instruct patient to lie still without talking and not to cross their legs
steps for ECG
1. wash hand, skin prep, wipe site with alcohol or to shave hair
2. apply self adhering electrodes and attach leads
for a 12 lead ECG: attach chest (precordial) leads:
V1 4th ICS at right sternal border
V2 4th ICS at left sternal border
V3 midway between V2 and V4
V4 5th ICS at midclavicular line
V5 left anterior axillary line at level of V4
V6 left midaxillary line at level of V4 (ICS)
limb leads, one lead on each limb. place electrodes firmly on the flat on the flat surface just above the wrists and ankles.
3. connect power cord and turn machine one
what r the major component of cardiac assessment
– The major elements of the cardiac exam include observation, palpation and, most importantly, auscultation (percussion is omitted). Initially, the patient should rest supine with the upper body elevated 30 to 45 degrees.
– assessment of pulse and blood pressure are important elements of the cardiac exam.
– An ecg is a component of the assessment
– The evaluation of the cardiovascular system focuses on the heart, but should also include an assessment for disease in the arterial system throughout the body. Atherosclerosis, the most common cardiovascular ailment in the western world, is a systemic disease.
what r the subjective data for cardiac assessment
– Past health history
– Medications –
– Lifestyle questions
physical examination on cardiac assessment
– General appearance
– Physical assessment: head-to-toe
– Percussion ( eliminated)
what r you looking for pulse in the cardiac assessment
– Irregularities of heart rhythm
– Quality, weak, bounding
– Pulse deficit, apical vs. radial
– Take for 1 full minute
– Check with ECG
what is precordium
– The area on the anterior chest wall overlying the heart and great vessels
– Heart is located between the lungs in the middle third of the thoracic cage, called the mediastinum
what is the position of the heart
– The heart extends from the second to the fifth intercostal space
– From the right border of the sternum to the left midclavicular line
what r the landmark for precordium
– Landmarks of the precordium include:
– Suprasternal notch
– Angle of Louis (Sternal angle)
– Midsternal line (MSL)
– Midclavicular line (MCL)
– Anterior, middle & posterior axillary lines (AAL, MAL, PAL)
– Intercostal spaces (ICS) 2nd right, 2nd left & 5th left
what area listen for heart sound
PQRST for angina
Encourage patient to notify staff immediately when pain occurs
Perform PQRST assessment
Administer oxygen according to protocol
Record P,BP, RR
Record an ECG if pain new in onset, severe or lasts > 10 mins.
Administer pain medication as ordered
Assess effectiveness of treatment
Notify medical officer
Repeat ECG at least half hourly while pain persists and when patient is pain free.