CET NHA Certified EKG Technician - Set 5 - Part 1

Correct Answer: About sixty beats per minute

The three hundred method divides three hundred by the number of large boxes between R waves, giving sixty beats per minute for five boxes. Memorizing the sequence three hundred, one fifty, one hundred, seventy-five, sixty, and fifty speeds estimation. Option a is incorrect because one hundred fifty beats per minute corresponds to two large boxes between R waves, not five. The wider R-to-R interval described represents a much slower rhythm than the one fifty range. Option c is incorrect because thirty beats per minute would correspond to ten large boxes between R waves, twice the interval described. Such a slow rhythm sits well below the five-box scenario in the question. Option d is incorrect because one hundred beats per minute corresponds to three large boxes between R waves rather than five. The wider interval in the scenario points to a slower rhythm than one hundred.

Correct Answer: About eighty beats per minute

The six-second method multiplies the QRS count in a six-second strip by ten, so eight QRS complexes give eighty beats per minute. This method is preferred for irregular rhythms where R-R intervals vary widely. Option a is incorrect because forty per minute would require only four QRS complexes in the same window. The patient's strip shows twice that many beats, so the rhythm is faster than the forty range suggests. Option b is incorrect because six QRS complexes in six seconds would multiply out to sixty per minute under the same method. The technician counted more than six on this strip, which pushes the calculation above sixty. Option c is incorrect because reaching one hundred per minute would require ten QRS complexes in a six-second window. With only eight visible beats on the strip, the rhythm stays comfortably below the hundred-per-minute threshold.

Correct Answer: About one hundred beats per minute

The fifteen hundred method divides fifteen hundred by the small-box count between R waves, so fifteen hundred divided by fifteen equals one hundred beats per minute. This method gives precise results for regular rhythms. Option b is incorrect because seventy-five beats per minute corresponds to twenty small boxes between R waves rather than fifteen. The shorter interval points to a faster rate than seventy-five. Option c is incorrect because sixty beats per minute corresponds to twenty-five small boxes between R waves. The fifteen-box interval is too short to produce a sixty-per-minute rate. Option d is incorrect because fifty beats per minute corresponds to thirty small boxes between R waves, double the interval described. The shorter R-R interval in the scenario produces a much faster rate.

Correct Answer: Count the flutter or P waves per minute

The atrial rate is counted by identifying the atrial activity, in this case flutter waves, and counting them over a measured interval. The ventricular rate counts QRS complexes, and in atrial flutter the two rates often differ. Option a is incorrect because counting QRS complexes gives the ventricular rate rather than the atrial rate, which can be quite different in atrial flutter. The two rates need separate counts in arrhythmias with AV block patterns. Option b is incorrect because the calibration mark length sets the gain reference and has nothing to do with rate counting. The standardization mark and rate counting are entirely separate concepts. Option d is incorrect because the patient's pulse reflects ventricular contractions felt at the radial artery and does not show atrial activity. Pulse and atrial rate often differ in atrial flutter and other AV-block rhythms.

Correct Answer: Three large boxes give one hundred

The memorized sequence is three hundred, one fifty, one hundred, seventy-five, sixty, and fifty for one through six large boxes between R waves. Three large boxes gives one hundred beats per minute under this rule. Option a is incorrect because one large box between R waves gives three hundred beats per minute, the start of the memorized sequence. One box represents a much faster rate than one hundred. Option b is incorrect because two large boxes between R waves gives one hundred fifty beats per minute, not one hundred. The sequence steps down at each interval rather than landing on one hundred at two boxes. Option c is incorrect because four large boxes between R waves gives seventy-five beats per minute, the next step down from one hundred. Four boxes is a slower rate than the question's target value.

Correct Answer: Atrial fibrillation with narrow QRS

An irregularly irregular rhythm with no discernible P waves and narrow QRS complexes is the textbook presentation of atrial fibrillation. The chaotic atrial activity replaces organized P waves with fibrillatory undulations on the baseline. Option b is incorrect because sinus arrhythmia is irregular but has clear P waves before every QRS and varies with respiration. The presence of P waves rules out fibrillation as the underlying rhythm. Option c is incorrect because normal sinus rhythm is regular with consistent R-R intervals and a P wave before every QRS. The irregularly irregular pattern described does not match a normal sinus rhythm. Option d is incorrect because atrial flutter with two-to-one block typically produces a regular ventricular rhythm around one hundred fifty with visible sawtooth flutter waves. Flutter would show waves, not the absence of organized atrial activity.

Correct Answer: First-degree AV block by criteria

A PR interval longer than zero point twenty seconds that is constant and conducts every P wave is the defining criterion for first-degree AV block. The block is usually benign and reflects slowed conduction through the AV node. Option a is incorrect because normal sinus rhythm requires the PR interval to be within zero point twelve to zero point twenty seconds. A consistently prolonged PR interval moves the rhythm out of the normal category into first-degree block. Option b is incorrect because Mobitz type one second-degree block features progressively lengthening PR intervals followed by a dropped QRS. A constant prolonged PR with every beat conducted is a different and more benign pattern. Option d is incorrect because third-degree complete AV block features atrial and ventricular activity that are completely dissociated rather than reliably conducted with each P. Every-beat conduction rules out complete block.

Correct Answer: Bundle branch block or ventricular origin

A QRS duration over zero point twelve seconds indicates a wide complex, which suggests bundle branch block, ventricular origin, paced beats, hyperkalemia, or drug effect. The wide QRS reflects abnormal or slowed conduction below the AV node. Option a is incorrect because a normal narrow QRS is below zero point twelve seconds by definition. The fourteen-hundredths measurement clearly exceeds the narrow QRS threshold and does not fit the normal category. Option c is incorrect because sinus tachycardia is defined by an elevated rate rather than a wide QRS. Sinus tachycardia at rest still uses the normal conduction pathway and produces narrow complexes unless a separate conduction issue is present. Option d is incorrect because first-degree AV block involves a prolonged PR interval rather than a wide QRS. PR and QRS are separate intervals with separate normal ranges.

Correct Answer: Torsades de pointes polymorphic VT

A prolonged QT interval increases the risk of torsades de pointes, a polymorphic ventricular tachycardia with QRS complexes that appear to twist around the baseline. This rhythm can degenerate into ventricular fibrillation if not corrected. Option a is incorrect because atrial fibrillation arises from atrial chaotic activity rather than from QT prolongation. AFib and long QT are not specifically linked as cause and effect on the EKG. Option b is incorrect because sinus tachycardia simply reflects elevated rate from physiologic or pharmacologic stimulation. Long QT does not predispose to sinus tachycardia, so the relationship in this question runs in another direction. Option c is incorrect because first-degree AV block involves prolonged PR conduction at the AV node rather than the ventricular repolarization issue that drives torsades. The two findings have different mechanisms entirely.

Correct Answer: Normal sinus rhythm

A regular rhythm at sixty to one hundred beats per minute with a P wave before every QRS, normal PR interval, and narrow QRS defines normal sinus rhythm. All five criteria of the systematic approach are met here. Option b is incorrect because sinus bradycardia requires a rate below sixty beats per minute. The seventy-five rate described falls in the normal range rather than the bradycardia range. Option c is incorrect because sinus tachycardia requires a rate above one hundred beats per minute. The seventy-five rate sits below the tachycardia threshold and does not meet the criterion. Option d is incorrect because atrial fibrillation is irregularly irregular with no discrete P waves. The regular rhythm with clear P waves described in the scenario rules out fibrillation entirely.

Correct Answer: Hyperkalemia from kidney failure

Tall, peaked, narrow T waves are the earliest classic finding of hyperkalemia, which often appears in patients with kidney failure. Worsening hyperkalemia adds prolonged PR, wide QRS, and eventually a sine wave pattern. Option a is incorrect because hypokalemia typically produces ST depression, flattened or inverted T waves, and prominent U waves rather than tall peaked T waves. The two potassium abnormalities cause opposite T wave changes. Option b is incorrect because hypocalcemia typically prolongs the QT interval rather than producing peaked T waves. Calcium effects target the ST segment and overall QT length rather than T wave shape directly. Option d is incorrect because hypercalcemia typically shortens the QT interval and may produce J waves rather than tall peaked T waves. The calcium effects on the EKG involve QT rather than T wave morphology specifically.

Correct Answer: Atrial flutter with two-to-one conduction

Atrial flutter typically has an atrial rate of two hundred fifty to three hundred fifty with sawtooth waves, and a two-to-one conduction ratio produces a regular ventricular rate near one hundred fifty. The pattern fits classic flutter. Option a is incorrect because atrial fibrillation is irregularly irregular and lacks the organized sawtooth waves of flutter. The regular ventricular response and discrete atrial waves rule out fibrillation as the rhythm. Option b is incorrect because multifocal atrial tachycardia features at least three different P-wave morphologies and an irregular ventricular response. Sawtooth waves and a regular rate do not match the multifocal pattern. Option c is incorrect because sinus tachycardia features normal upright P waves before every QRS rather than the sawtooth waves seen in flutter. Sinus tachycardia uses the SA node origin and has different morphology.

Correct Answer: Sinus bradycardia with normal conduction

A regular rhythm below sixty beats per minute with normal P waves, PR interval, and narrow QRS meets the criteria for sinus bradycardia. The SA node still acts as the pacemaker, just at a slower rate than normal. Option b is incorrect because junctional escape rhythm typically lacks normal upright P waves before every QRS and may show inverted or absent P waves. The presence of normal P waves rules out junctional origin. Option c is incorrect because normal sinus rhythm requires the rate to be between sixty and one hundred. The forty-five rate falls below that range and meets bradycardia criteria. Option d is incorrect because idioventricular rhythm features wide QRS complexes from a ventricular pacemaker, not the narrow QRS described. Idioventricular rhythms also typically lack any visible P waves.

Correct Answer: Mobitz type one second-degree block

Progressively lengthening PR intervals followed by a dropped QRS describes Mobitz type one second-degree AV block, also called Wenckebach. The classic teaching is longer, longer, longer, drop, then you have a Wenckebach. Option a is incorrect because first-degree AV block has a constant prolonged PR interval with every beat conducted, not progressive lengthening with dropped beats. The two blocks have different patterns and different prognoses. Option c is incorrect because Mobitz type two block has a constant PR interval for conducted beats with sudden dropped beats, not progressive lengthening. The two Mobitz patterns differ in whether the PR varies before the drop. Option d is incorrect because third-degree complete AV block features atrial and ventricular activity that are completely dissociated with no conducted relationship. A pattern that resets after a drop is not complete block.

Correct Answer: Mobitz type two second-degree block

A constant PR interval with sudden dropped QRS without prior lengthening describes Mobitz type two second-degree AV block. This block usually sits below the AV node and carries a higher risk of progression to complete heart block. Option a is incorrect because first-degree AV block conducts every beat with a prolonged but constant PR interval. The presence of dropped beats rules out first-degree block, which has no dropped QRSs at all. Option b is incorrect because Mobitz type one features progressively lengthening PR intervals before the drop, not constant PRs with sudden drops. The two Mobitz types are distinguished by exactly this difference. Option d is incorrect because sinus arrhythmia is a normal variant with respiratory variation in rate, not a conduction block with dropped beats. Sinus arrhythmia has every P followed by a QRS, just at varying intervals.

Correct Answer: Third-degree complete AV block

Third-degree complete AV block features atrial and ventricular activity that march completely independently of each other, with the atria continuing at their rate and an escape pacemaker driving the slower ventricular rate. The dissociation is the defining feature. Option a is incorrect because sinus bradycardia has a P wave before every QRS at a consistent slow rate. The dissociation between atria and ventricles described in the scenario is incompatible with sinus bradycardia. Option b is incorrect because atrial flutter shows sawtooth waves and a consistent conduction ratio to the ventricles even when the block ratio is high. The complete absence of relationship between P and QRS rules out flutter. Option c is incorrect because junctional rhythm originates from the AV junction and typically lacks normal upright P waves before every QRS. The atrial rate at eighty with a separate slow ventricular rate fits a complete block.

Correct Answer: Premature ventricular complex

A premature ventricular complex appears as an early wide bizarre QRS without a preceding P wave, usually followed by a compensatory pause. The wide complex reflects ventricular origin that bypasses the normal conduction pathway. Option b is incorrect because a premature atrial complex has a preceding early P wave and a narrow QRS, since the impulse uses the normal conduction system from above. The wide QRS rules out atrial origin entirely. Option c is incorrect because a premature junctional complex has a narrow QRS and may have an inverted or absent P, but the QRS itself is not wide and bizarre. Junctional origin still uses the normal His-Purkinje system below. Option d is incorrect because a normal sinus beat occurring early is not technically premature in the ectopic sense and would have a narrow QRS with a preceding P. The wide bizarre morphology rules out a normal beat.

Correct Answer: Pulseless ventricular tachycardia

A regular wide-complex tachycardia with no P waves and a pulseless patient is pulseless ventricular tachycardia, which is a shockable rhythm. Treatment requires immediate CPR and defibrillation as part of advanced cardiac life support. Option a is incorrect because atrial fibrillation with aberrancy would be irregularly irregular rather than regular. The regular pattern described rules out fibrillation as the underlying rhythm. Option b is incorrect because sinus tachycardia uses the normal conduction system and produces narrow QRS complexes. A wide-complex tachycardia at this rate is not sinus tachycardia. Option d is incorrect because asystole shows a flat line with no electrical activity on the monitor. The wide-complex tachycardia described is the opposite of the absent electrical activity that defines asystole.

Correct Answer: Ventricular fibrillation

Ventricular fibrillation is a chaotic, irregular pattern with no identifiable QRS complexes and is the most common shockable rhythm in cardiac arrest. Immediate defibrillation and high-quality CPR are the treatments that improve survival in this rhythm. Option a is incorrect because atrial flutter shows organized sawtooth waves and usually some QRS complexes from conducted beats. The chaotic pattern with no QRS rules out flutter immediately. Option c is incorrect because asystole is a flat line with no electrical activity rather than chaotic waves. The two rhythms look very different on the monitor and require different responses, with asystole being non-shockable. Option d is incorrect because pulseless electrical activity shows an organized rhythm on the monitor with no pulse, not chaotic waves without QRS. PEA features structured electrical activity while VF produces only chaos on the strip.

Correct Answer: Asystole, high-quality CPR and epinephrine

Asystole on the monitor with confirmation in two leads is a non-shockable rhythm treated with high-quality CPR and epinephrine while searching for reversible causes. Defibrillation has no role because there is no organized electrical activity to convert. Option a is incorrect because asystole is explicitly non-shockable, and defibrillating a flat line provides no benefit and may delay effective interventions. CPR and medication, not shock, are the appropriate response. Option b is incorrect because ventricular fibrillation appears as chaotic waves rather than a flat line and is treated with defibrillation, not CPR alone. Both the rhythm name and the treatment plan are mismatched in this option. Option c is incorrect because observing a pulseless patient quietly while in arrest is never appropriate and would let the patient die without intervention. Any pulseless arrest demands immediate active resuscitation.