![]() Sinus tachycardia displays a regular, usually narrow-complex tachycardia, with normal P waves preceding each QRS complex ( Fig. Walls MD, in Rosen's Emergency Medicine: Concepts and Clinical Practice, 2018 Sinus Tachycardia Consider carotid sinus massage or adenosine to distinguish sinus node reentry tachycardia (which will usually terminate) from ST (which will only slow without terminating). Sinus node reentry tachycardia, generally an uncommon form of supraventricular tachycardia, can mimic ST in P-wave morphology. ST with first-degree AV block may be difficult to diagnose if the sinus P wave is buried in the T wave ( Fig. Atrial tachycardia or atrial flutter with 2:1 block may be mistaken for ST but usually does not have distinct upright P waves evident in leads II, III, aVF ( Fig. It is present during exercise but can occur at rest when associated with any number of conditions. Sinus tachycardia (ST) is characterized by a sinus P wave at a rate of more than 100 per minute, usually followed by a QRS complex that is usually narrow (but may be wide in the presence of an underlying BBB) ( Fig. Nora Goldschlager MD, in Arrhythmia Essentials (Second Edition), 2017 Description ![]() Patients with a low ejection fraction may be unable to increase their stroke volume to compensate for the reduction in heart rate, and as a result the β-blocker–mediated decrease in heart rate can cause an abrupt and dangerous decrease in blood pressure.īrian Olshansky MD. However, β-blockers must be used with caution in patients susceptible to bronchospasm and in patients with impaired cardiac function. Treatment may include IV administration of a β-blocker to lower the heart rate and decrease myocardial oxygen demand. Strategies to decrease the likelihood of sinus tachycardia include avoidance of vagolytic drugs such as pancuronium, ensuring adequate anesthetic depth, maintenance of euvolemia, correction of hypercarbia, avoidance of hypoxemia, antibiotic treatment of suspected infection, use of the lowest effective dose of inotropic support for heart failure (many inotropes increase heart rate), and prompt treatment of myocardial ischemia ( Table 8.1). During tachycardia the length of diastole is shortened more than the length of systole, so the time for coronary artery blood flow is decreased at the same time as cardiac work is increased by the tachycardia. In patients with ischemic heart disease, diastolic dysfunction, or CHF, the heart rate increase above normal sinus rhythm can lead to significant clinical deterioration because of increased oxygen demand, increased wall stress, and a decrease in coronary perfusion. Potential intraoperative causes include sympathetic stimulation, vagolytic drug administration, hypovolemia, “light” anesthesia, hypoxia, hypercarbia, heart failure, cardiac ischemia, fever, and infection. Reasons for sinus tachycardia range from simple to complex. If a specific cause of sinus tachycardia can be determined, it should be treated. ![]() Treatment of sinus tachycardia is directed toward correcting the underlying cause. Sinus tachycardia is usually well tolerated in young healthy patients. Intake of substances such as caffeine and cocaine may also cause sinus tachycardia. It can occur in an awake patient as part of the normal physiologic response to stimuli (e.g., fear, pain, anxiety) or as a pharmacologic response to medications such as atropine, ephedrine, or other vasopressors. Sinus tachycardia without hemodynamic instability is not life-threatening. It is the most common supraventricular dysrhythmia in the operating room. Typically it is a nonparoxysmal increase in heart rate that speeds up and slows down gradually. Sinus tachycardia is caused by acceleration of SA node discharge due to either sympathetic stimulation or parasympathetic suppression. The PR interval is normal unless a co-existing conduction block exists. The ECG shows a normal P wave before every QRS complex. When sinus rhythm exceeds 100 bpm, it is considered sinus tachycardia. Normal sinus rhythm in a patient at rest is under the control of the sinus node, which fires at a rate of 60–100 bpm. Hines MD, in Stoelting's Anesthesia and Co-Existing Disease, 2018 Sinus Tachycardia
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