Provided is an ECG image of Ventricular tachycardia.
Identify the wave pattern and describe it.
Rapid, regular wide QRS complexes with no visible P waves.
Chaotic electrical activity with no identifiable QRS complexes.
Early P waves with a different shape followed by a normal QRS.
Progressive lengthening of the PR interval until a QRS is dropped.
The Correct Answer is A
Choice A rationale
Ventricular tachycardia is characterized by rapid, repetitive firing from an ectopic focus or reentrant circuit within the ventricular myocardium. Because the impulse does not follow the rapid His-Purkinje system, ventricular depolarization is slow and inefficient, resulting in QRS complexes wider than 0.12 seconds. The high rate, typically 100 to 250 beats per minute, overrides the sinus node, meaning P waves are buried or dissociated. This severely compromises cardiac output due to reduced filling time.
Choice B rationale
Chaotic electrical activity without any identifiable QRS complexes describes ventricular fibrillation. In this state, the ventricles merely quiver and do not provide any effective contraction or cardiac output. This is a pulseless rhythm that requires immediate defibrillation to restore organized activity. While ventricular tachycardia is also dangerous, it maintains organized QRS complexes, whereas fibrillation is a total loss of electrical and mechanical organization, appearing as a wavy or jagged baseline on the ECG.
Choice C rationale
Early P waves with a different shape followed by a normal QRS are known as premature atrial contractions. These occur when an irritable focus in the atrium fires before the next expected sinus impulse. The resulting QRS is usually narrow because the impulse still travels through the normal ventricular conduction system. This is a common, often benign finding and does not resemble the wide, rapid, and potentially lethal ventricular complexes seen in tachycardia.
Choice D rationale
A progressive lengthening of the PR interval until a QRS complex is dropped is the hallmark of Mobitz Type I or Wenckebach second-degree heart block. This occurs due to a delay at the atrioventricular node that worsens with each beat until conduction fails entirely for one cycle. This is an atrial-ventricular conduction issue, not a primary ventricular arrhythmia. Ventricular tachycardia does not involve PR interval cycles as the ventricles are firing independently.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
Choice A rationale
Thickening of the ventricular walls and the septum is the hallmark of hypertrophic cardiomyopathy, not pericarditis. In that condition, the muscle tissue becomes abnormally thick, which can make it harder for the heart to pump blood and may lead to arrhythmias. Pericarditis does not involve the growth or thickening of the myocardium itself; it is strictly a disorder of the protective layers surrounding the heart. Explaining the condition this way would be scientifically inaccurate.
Choice B rationale
Acute pericarditis is defined as the inflammation of the pericardium, which is the thin, two-layered membranous sac that encloses the heart. This inflammation often leads to chest pain that worsens with deep breathing or lying flat and may produce a pericardial friction rub. The inflammation can be caused by infections, autoimmune disorders, or trauma. This statement correctly identifies the anatomical location and the pathological process involved, making it the most appropriate explanation for patient education.
Choice C rationale
Excessive stretching of the ventricles is associated with dilated cardiomyopathy, a condition where the heart chambers enlarge and the muscle weakens. This stretching results in a decreased ejection fraction and signs of heart failure. Pericarditis involves the external sac and does not primarily cause the heart muscle to stretch out. Using this description would confuse the patient about the nature of their diagnosis, as it describes a structural muscle failure rather than an inflammatory process.
Choice D rationale
Compression of the myocardium due to fluid accumulation describes a pericardial effusion or cardiac tamponade. While these can be complications of acute pericarditis, they are not the definition of the disease itself. Pericarditis is the inflammation of the membranes, which may or may not lead to significant fluid buildup. It is important to distinguish the primary inflammatory cause from the potential secondary effect of fluid pressure to ensure the patient understands why they have pain.
Correct Answer is A
Explanation
Choice A rationale
Sinus tachycardia is defined by a heart rate exceeding 100 beats per minute, originating from the sinoatrial node. The rhythm remains regular because the electrical impulses follow the normal conduction pathway through the atria and ventricles. Each QRS complex is preceded by a visible P wave, and the PR interval remains within the normal range of 0.12 to 0.20 seconds. This rhythm is often a physiological response to stress, fever, exercise, or pain.
Choice B rationale
A heart rate between 60 and 100 beats per minute with a regular rhythm defines normal sinus rhythm. In this state, the sinoatrial node fires at a standard physiological pace, and the electrical conduction through the heart is unimpeded. Because sinus tachycardia specifically refers to a rate that is faster than this normal range, this choice does not accurately describe the wave pattern in question. It represents a healthy cardiac electrical state rather than a tachycardic one.
Choice C rationale
An irregular rhythm with changing P wave morphology is characteristic of rhythms like wandering atrial pacemaker or multifocal atrial tachycardia. These conditions involve multiple ectopic foci within the atria competing for dominance, rather than a single impulse from the sinoatrial node. In true sinus tachycardia, the P waves should look identical to one another because they are all generated from the same location. Therefore, this description is inconsistent with the diagnostic criteria for sinus tachycardia.
Choice D rationale
A rapid rate without visible P waves and narrow QRS complexes is typical of supraventricular tachycardia or atrial fibrillation, depending on the regularity of the rhythm. In sinus tachycardia, the P wave must be present and clearly associated with the QRS complex because the rhythm originates from the sinus node. The absence of P waves suggests that the rhythm is originating from a different part of the atrium or the atrioventricular junction, which is incorrect.
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