CHAPTER 36: Care of Patients with Dysrhythmias

Dysrhythmias are abnormal rhythms that affect its ability to pump OXYGENATED blood throughout the body. *CAD, electrolyte imbalance,, changes in oxy and drug toxicity can cause dysrhythmias Specialized myocardial cells regulate heart rate, rhythm and possess: 1. automaticity (pacing function): ability of cardiac cells to generate an electrical impulse spontaneously and repetitively. Normally, only primary pacemaker cells (sinoarial, SA, nodes) can generate the impulse. *in times of myocardial ischemia, any cardiac cell may produce electrical impulse 2. excitability: ability of non-pace maker cells to response to electrical impulse and to dedpolarize (become positive from negative state) 3. conductivity: ability to send electric stimulus from cell membrane to cells membrane. Therefore, excitable cells depolarize in rapid succession until every cell is positively charged. Conduction is messed up when conduction is too rapid or slow *wave of depolarization is depicted as the P wave and QRS complex 4. contractility: ability of atrial and ventricular muscles to shorten fiber length in response to electrical impulse, causing sufficient pressure to push blood forward through the heart. *contractility is the mechanical activity of the heart Cardiac conduction: SA node . conducts impulses at rate of 60-100 bpm . sympathetic system increases rate, parasym decreases it . impulse moves through atrium (atrial depolarization) **reflected in P wave . atrial contraction should follow atrial depolarization AV node . contains bundle of his and consists of “transitional zone”