The rhythm in strip four is sinus bradycardia with bigeminal premature ventricular complexes (PVCs), that appear to be R-on-T PVCs. Using the 6 second method the atrial rate is regular at 40 bpm, whilst the ventricular rate is irregular at 80 bpm. The P waves are smooth and rounded, though the second P wave is slightly pointed, and are 0.12 seconds in duration. The PR interval is slightly prolonged at 0.24 seconds and there is approximately 1 mm of depression. The QRS complex is normal at 0.08 seconds in duration. The QT interval is difficult to determine as the PVC complexes cut the T wave off, however it is less than half of the R-R interval. The ST segment has 1 mm of depression. The T wave appears upright in beat 1 but is indeterminable in beats 3 and 4.
There are many reasons that people experience PVCs. Some of these include acid-base or electrolyte imbalances, coronary artery disease, cardiomyopathy, medications, exercise, heart failure, hypoxia, stress, anxiety, stimulants such as caffeine or tobacco, valvular heart disease, or ventricular aneurysm (Aehlert, 2018, p. 170). It is important for the nurse caring for a patient with PVCs to assess the patient for chest pain, dizziness, lightheadedness, dyspnea, and to perform vital signs at regular intervals (Farzam & Richards, 2021, History and Physical). When assessing the patient, it is important that the nurse assess that the PVCs have mechanical capture. The patient will need to be on a telemetry monitor and the nurse should be prepared to perform 12-lead ECGs and draw labs (Farzam & Richards, 2021, Evaluation). The nurse should also anticipate cardiology evaluation. This rhythm is dangerous as the R-on-T PVCs could precipitate ventricular fibrillation or ventricular tachycardia (Aehlert, 2018, p. 169-170). I would expect the patient to be treated with oxygen and antiarrhythmic medications, but because the underlying rhythm is sinus bradycardia the nurse should also be prepared to treat the patient for this rhythm. Treatment would also depend on 12-lead ECG analysis and symptoms that the patient is experiencing, i. e. if the rhythm is in response to coronary syndrome or myocardial infarction, which may be the case as the ST segment does have some minor depression.
Aehlert, B. (2018). ECGs made easy. Elsevier.
Farzam, K., & Richards, J. (2021). Premature ventricular contraction. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK5329