Cardiac Dysrhythmias Advanced Questions & Answers

What is the pacemaker of the heart normally? - ANSWERSSA Node. Where does the SA node originate? - ANSWERSUpper right atrium. What is the pathway of conduction in the heart? - ANSWERSSA node - atria - AV node - bundle of his - bundle branches - purkinje fibers - ventricles. What does stimulation of the vagus nerve cause? - ANSWERSDecreased firing of the SA node and slowed impulse conduction of the AV node. What does stimulation of the sympathetic nerves cause? - ANSWERSIncreased firing of the SA node and increased impulse through the AV node, and cardiac contractility. What does the P wave represent? - ANSWERSTime for the passage of the electrical impulse through the atrium causing atrial depolarization (contraction). What is the normal P wave duration? - ANSWERS0.06 - 0.12. What is a possible variation cause of a P wave? - ANSWERSDisturbance in conduction within the atria. What does the PR interval represent? - ANSWERSThe measure from the beginning of the P wave to the beginning of the QRS complex, represents time taken for impulse to spread through the atria, AV node, and bundle of his, the bundle branches and purkinje fibers, to a point of immediately preceding ventricular contraction. What is the normal PR interval? - ANSWERS0.12 - 0.20. What is a possible variation cause with PR interval? - ANSWERSDisturbance in conduction usually in the AV node, bundle of his, or bundle branches but can be atria as well. What does the QRS interval represent? - ANSWERSMeasure from beginning to end of QRS complex, represent time taken for depolarization (contraction) of both ventricles (systole). What is the normal QRS interval? - ANSWERS0.12. What is a possible variation cause with the QRS interval? - ANSWERSDisturbance in conduction in the bundle branches or in the ventricles. What does the ST Segment represent? - ANSWERSMeasure from the S wave of the QRS complex to the beginning of the T wave; represents time between ventricular depolarization and repolarization (Diastole); should be isoelectric (flat). What is the normal ST segment? - ANSWERS0.12. What is a possible variation cause with the ST segment? - ANSWERSDisturbance usually caused by ischemia, injury or infarction. What does the T wave represent? - ANSWERSRepresents time for ventricular repolarization, should be upright. What is the normal T wave? - ANSWERS0.16. What is a possible variation cause for a T wave? - ANSWERSDisturbance usually caused by electrolyte disturbances; ischemia or infarction. What does the QT interval represent? - ANSWERSMeasured from beginning of the QRS to end of the T wave, represents time taken for entire electrical depolarization and repolarization of the ventricles. What is the normal QT interval? - ANSWERS0.34 - 0.43. What is the possible variation cause for a QT interval? - ANSWERSDisturbance usually affected repolarization more than depolarization and cause by drugs, electrolyte imbalances, and change in hr. What is the normal firing of the SA Node? - ANSWERS60 - 100 times/min. What is the normal firing of the AV Node? - ANSWERS40 - 60 times/min. What is the normal firing of the Bundle of HIS/Purkinje Fibers? - ANSWERS20 - 40 times/min. What are the characteristics of Normal Sinus Rhythm? - ANSWERS60 - 100 bpm, regular, normal P wave/PR and QRS. What are characteristics for Sinus Bradycardia? - ANSWERS 60 bpm and regular, normal P wave/PR and QRS. What are causes of Sinus Bradycardia? - ANSWERSMay be normal in athletes and sleep, response to carotid artery massage, valsalva maneuver, hypothermia, increased ICP, vagal stimulation and meds. What disease states cause Sinus Bradycardia? - ANSWERSHypothyroidism, increased ICP, hypoglycemia, and inferior wall MI. What are the signs/symptoms of Sinus Bradycardia? - ANSWERSPale, cool skin, hypotension, weakness, angina, dizziness, syncope, confusion, disorientation SOB. What is treatment for Sinus Bradycardia? - ANSWERSAtropine for the patient with symptoms. Pacemaker may be required. Drugs - hold or d/c. What is the characteristics of Sinus Tachycardia? - ANSWERS101 - 200 bpm and regular. Normal P/PR and QRS. What are the causes of Sinus Tachycardia? - ANSWERSPhysiologic stressors such as exercise, fever, hypotension, hypovolemia, anemia, hypoxia, hypoglycemia, MI, HF, hyperthyroidism, anxiety and fear. Drugs. What are the signs and symptoms of Sinus Tachycardia? - ANSWERSDizziness, dyspnea, hypotension due to decreased CO, angina, infarction. What is the treatment for Sinus Tachycardia? - ANSWERSTreat the underlying cause. Vagal maneuvers can be attempted. IV beta blockers can reduce HR and decrease myocardial oxygen consumption. What are the characteristics of Atrial Flutter? - ANSWERS200 - 350 bpm and regular, ventricular or 100 bpm and may be regular or irregular. Abnormal P wave shape, sawtooh pattern, more flutter waves the qrs complexes, no measure PR and normal QRS usually. What causes Atrial Flutter? - ANSWERSCoronary artery disease, hypertension, mitral valve disorder, pulmonary embolism, chronic lung disease, cor pulmonale, cardiomyopathy, hyperthyrodisim, drugs - dig, quinidine and epi. What are the possible side effects of Atrial Flutter? - ANSWERSDecrease CO, HF, and increased risk of stroke.