Heart Beats: Rhythm Self-Quiz: Fast and Deadly
Mr. M, 52, comes to the ED complaining of intermittent palpitations, shortness of breath, and lightheadedness. Triage takes Mr. M back into the treatment area after a quick evaluation. His vital signs are BP, 140/80; pulse, 148 and regular; respirations, 18; and SpO2, 97% on room air.
While a colleague obtains peripheral I.V. access, you attach a cardiac monitor, which shows sinus tachycardia with frequent premature ventricular contractions (PVCs). Next, you use the SAMPLE mnemonic to conduct a secondary survey:
Signs and symptoms: palpitations, shortness of breath with exertion; lightheadedness when changing from a supine to a sitting position; no chest pain, nausea, or other signs and symptoms
Allergies: none known
Medications: none
Past medical history: none
Last meal: light breakfast 2 hours ago
Event history: signs and symptoms started about a half-hour ago while working in his basement.
Mr. M says that now his chest "feels funny," and he feels as if he 's "going to pass out." Mr. M becomes unresponsive, apneic, and pulseless and the monitor shows a wide-complex tachycardia.
In a previous Heart Beats, we reviewed the five basic steps of rhythm analysis:
* Determine the rhythm by measuring the distance between R waves and noting any variations in R-wave regularity. Determine if a 0.12-second or greater variance exists between the shortest and longest R-wave variations.
Figure. Rhythm strip
* Calculate the heart rate, using the rapid rate calculation (counting the number of R waves in a 6-second strip and multiplying by 10 to calculate the heart rate per minute), for regular or irregular rhythms. For a regular rhythm, you can also use the precise rate calculation: Count the number of small squares between two consecutive R waves, and divide this number into 1,500 (the number of small squares in a 1-minute rhythm strip) to obtain the heart rate in beats per minute. Report the atrial and ventricular rates
While a colleague obtains peripheral I.V. access, you attach a cardiac monitor, which shows sinus tachycardia with frequent premature ventricular contractions (PVCs). Next, you use the SAMPLE mnemonic to conduct a secondary survey:
Signs and symptoms: palpitations, shortness of breath with exertion; lightheadedness when changing from a supine to a sitting position; no chest pain, nausea, or other signs and symptoms
Allergies: none known
Medications: none
Past medical history: none
Last meal: light breakfast 2 hours ago
Event history: signs and symptoms started about a half-hour ago while working in his basement.
Mr. M says that now his chest "feels funny," and he feels as if he 's "going to pass out." Mr. M becomes unresponsive, apneic, and pulseless and the monitor shows a wide-complex tachycardia.
In a previous Heart Beats, we reviewed the five basic steps of rhythm analysis:
* Determine the rhythm by measuring the distance between R waves and noting any variations in R-wave regularity. Determine if a 0.12-second or greater variance exists between the shortest and longest R-wave variations.
Figure. Rhythm strip
* Calculate the heart rate, using the rapid rate calculation (counting the number of R waves in a 6-second strip and multiplying by 10 to calculate the heart rate per minute), for regular or irregular rhythms. For a regular rhythm, you can also use the precise rate calculation: Count the number of small squares between two consecutive R waves, and divide this number into 1,500 (the number of small squares in a 1-minute rhythm strip) to obtain the heart rate in beats per minute. Report the atrial and ventricular rates
References: 1. American Heart Association. Advanced Cardiovascular Life Support (ACLS) Provider Manual. Dallas, TX: American Heart Association; 2011. [Context Link] 2. Compton S. Ventricular tachycardia. eMedicine. http://emedicine.medscape.com/article/159075-overview. [Context Link] RESOURCE 2010 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2010;122(18 suppl 3):S640-S933.