Cardiac Monitoring Skills NRSG450 Module One

Goals Student Will Be Able To Discuss Cardiac Monitoring And Correctly Place Chest Leads. Student Will Be Able To Interpret A Rhythm Strip For Cardiac Rate, Wave Morphology, Direction, Duration And Relationships To Other Waves. Student Will Recognize Normal From Abnormal Rhythms. Student Will Recognize Basic Sinus, Atrial, Junctional And Ventricular Rhythm Variations. Student Will Identify Lethal Rhythms.

Background of Electrical Flow of the Heart Electricity stimulates the heart muscle to contract. It spreads through the heart sequentially changing the polarity of the cell’s interior from negative to positive (depolarization). This causes contraction of the muscle. The internal cell positive polarity changes back to negative (repolarization) and the muscle relaxes. This process proceeds through cell-to-cell communication and high speed tracts in the atria and ventricles.

Anchoring the Information Electricity stimulates the heart muscle to contract. The internal cell is Negatively charged at rest. Stimulating the change of the cell’s internal and external polarity is called Depolarization. Depolarization produces Contraction of the muscle. Repolarization is the return of the internal cell negative polarity and muscle Relaxation. Depolarization and repolarization occur Sequentially. These processes proceed through Cell-to-cell communication and high speed tracts.

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Background of Electrical Flow of the Heart Depolarization-repolarization involves the exchange movement of sodium and potassium across the cell wall with calcium modulation. This exchange sets the rate of the electrical spread. This process, including a rest period, is called the action potential curve. Butler.cc.tut.fi Action Potential Curve Intracellular Cell wall Extracellular

Background of Electrical Flow of the Heart Each heart cell is able to start the depolarization process – automaticity. Excitability is term given to a cell responsiveness to a electric stimulus. The ability of a cell to transmit a stimulus to another cell is contractivity. Contractility is a measure of the cell’s ability to contract upon electrical stimulus. These processes are influenced by the autonomic nervous systems & medications.

Background of Electrical Flow of the Heart The sino-atrial (SA) node is usually the group of cells that trigger depolarization. This is why the SA node is known as the heart’s pacemaker. The SA node usually sets the heart’s rate at 60 – 100 beats per minute.

Anchoring the Information Depolarization and repolarization involves the exchange movement of Sodium and Potassium across the cell wall with calcium modulation. This exchange sets the Rate of the electrical spread and muscle Contraction.

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Anchoring the Information Ability to start the depolarization process. Measure of cell’s ability to contract. Cell’s responsiveness to a electric stimulus. Ability of cell to transmit a stimulus to another cell. These processes are influenced by the autonomic nervous systems & medications Automaticity Autonomic nervous system Conductivity Contractility Excitability

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Background of Electrical Flow of the Heart The flowing electricity is summarized to give a general direction. This is called the vortex. The vortex is the electrical direction viewed on the monitor. Electrical flow toward a positive electrode gives a upward deflection. Flow away from the positive electrode gives a downward deflection. cc.stimula.edu Lead II + -

Background of Electrical Flow of the Heart A straight line is called the isoelectric line. It is seen when no electrical flow is detected in the heart.

Reading the Electrical Flow of the Heart The electrical activity of the heart is picked up be electrodes, travels through the wires to a heated stylus and transferred to specially designed EKG paper.

Reading the Electrical Flow of the Heart EKG is recorded on graph paper traveling at 25mm per second The horizontal axis is time. –1 small block=1mm=0.04 sec –5 small blocks= 1 big block = 5mm = 0.2 sec –5 big blocks = 1 second –30 big blocks = 6 seconds The vertical axis is voltage. –1 small block =.01 mv –10 small blocks=2 big blocks = 1 mv

Reading the Electrical Flow of the Heart One heart beat or an electrical wave propagation Depolarization wave Heart muscle contraction

Reading the Electrical Flow of the Heart

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Reading the Electrical Flow of the Heart p wave = atrial depolarization Accounts for the time electrical stimulation moves across the atria. Duration 0.06 – 0.12 sec (2 small blocks> 4 small blocks) Located before QRS complex Height 2-3 mm ( mv) Shape rounded & positive (upright) Suran rutgers.edu

Reading the Electrical Flow of the Heart PR interval involves the atrial and nodal depolarization Measure from beginning of p wave to the beginning of the QRS Duration 0.12 – 0.20 sec

Reading the Electrical Flow of the Heart Ventricular depolarization is represented by the QRS complex locationlocation Location follows the PR interval. Duration seconds Amplitude dependent on Lead (~5-30 mm) Configuration dependent on Lead Deflection usually a combination of negative and positive, varies with leads Schwimmin

Reading the Electrical Flow of the Heart ST segment from the end of the S wave to the beginning of T wave Usually isoelectric, May be from mm from the isoelectric line

Reading the Electrical Flow of the Heart T wave is ventricular repolarization Location follows the s wave Configuration is round & smooth (looks like a big p wave) Deflection is usually positive

Reading the Electrical Flow of the Heart QT segment is measured from the beginning of the QRS complex to the end of the T wave. Duration is rate dependent Not routinely measured

Reading the Electrical Flow of the Heart