A 62-year-old man with coronary artery disease (CAD) presents with presyncope. His physical examination is normal except for bradycardia (pulse 56 beats/min) and an irregular pulse. The electrocardiogram (ECG) shows Wenckebach’s type atrioventricular (AV) block. Which of the following are you most likely to see on the ECG?
Wenckebach, or type I second-degree AV block, is characterized on ECG by progressive lengthening of the PR interval until there is a nonconducted P wave. The magnitude of PR lengthening declines with each beat, so the RR intervals characteristically shorten prior to the dropped beat. It is almost always caused by abnormal conduction across the AV node, and the QRS complex is usually of normal duration.
A 72-year-old woman had a pacemaker inserted 4 years ago for symptomatic bradycardia because of AV nodal disease. She is clinically feeling well and her ECG shows normal sinus rhythm at a rate of 68/min but no pacemaker spikes. Her pacemaker only functions when the ventricular rate falls below a preset interval. Which of the following best describes her pacemaker function?
The ventricular inhibited (VVI) pacemaker functions when the heart rate falls below a preset interval. If a QRS is detected, the pacemaker is inhibited. If a QRS is not sensed, the pacing stimulus is not inhibited and the ventricle is stimulated.
A 42-year-old man develops shortness of breath (SOB) and chest pain 7 days after an open cholecystectomy. His blood pressure is 145/86 mm Hg, pulse is 120/min, respirations 24/min, and oxygen saturation of 97%. Pulmonary embolism is clinically suspected. Which of the following is the most common ECG finding of pulmonary embolism?
Sinus tachycardia is the most common ECG finding in pulmonary embolism. The specific ECG signs of pulmonary embolism such as the S1, Q3, T3 are rarely seen except in cases of massive pulmonary embolism. In submassive pulmonary emboli, the ECG may show nonspecific ST changes and sinus tachycardia. On occasion, pulmonary embolism can precipitate atrial flutter or fibrillation. One of the most useful roles of the ECG is to rule out MI when a massive embolism is present.
A 63-year-old woman develops exertional angina and has had two episodes of syncope. Examination shows a systolic ejection murmur with radiation to the carotids and a soft S 2. Which of the following is the most likely diagnosis?
Aortic stenosis is most likely to be associated with angina pectoris, syncope, and exertional dyspnea. Exertional syncope is caused by either systemic vasodilation in the presence of fixed or inadequate cardiac output, an arrhythmia, or both. Syncope at rest is most frequently a result of a transient ventricular tachyarrhythmia.
A 42-year-old man with known valvular heart disease develops a fever for 1 week. He appears unwell; findings include a pansystolic murmur at the apex that radiates to the axilla and a soft S1 sound. He has petechiae on his conjunctival sac, linear hemorrhages under a few fingernails, and painful, tender, and erythematous nodules on some of the distal fingertips. Which of the following is the most responsible mechanism for these physical findings?
Common findings in infective endocarditis include petechiae, Roth’s spots, Osler’s nodes, Janeway lesions, splinter hemorrhages, stroke, and infarction of viscera, or extremities. Many of the complications are thought to be embolic but may include vasculitis. Autopsy studies reveal that many systemic emboli go unrecognized. Brain, lung, coronary arteries, spleen, extremities, gut, and eyes are common locations for emboli.
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Which of the following antiarrhythmic drugs mediates its effect by interfering with movement of calcium through the slow channel?
The slow channel for calcium assumes considerable importance in the region of the sinus node and AV node. For verapamil, this results in both antiarrhythmic and negative inotropic effects. Different classes of calcium channel blockers have differential effects on these slow channels, explaining the different clinical properties of the various calcium channel blocking drugs.
A 67-year-old man presents with an anterior myocardial infarction (MI) and receives thrombolytic therapy. Three days later, he develops chest pain that is exacerbated by lying down, and his physical findings are normal except for a friction rub. His ECG shows evolving changes from the anterior infarction but new PR-segment depression and 1-mm ST-segment elevation in all the limb leads. Which of the following is the most likely diagnosis?
Pericarditis secondary to transmural infarction is very common and most cases appear within 4 days. The most common manifestation of pericarditis is a friction rub along the left sternal border. It is evanescent, lasting only a few days. The pain is usually perceived by the patient to be different than that of the infarct. It is worsened by inspiration, swallowing, coughing, or lying down. It frequently is associated with a low-grade fever
Which of the following best describes the effect of calcium ions on the myocardium?
Positively inotropic is the best description of the effect of calcium ions on the myocardium Calcium plays a role in excitation– contraction coupling, and in possible drug effects and heart failure.
A 22-year-old primagravida woman develops hypertension at 28 weeks. She is asymptomatic and the examination is normal except for 1+ pedal edema. Her complete blood count, liver enzymes, and electrolytes are normal. The urinalysis is positive for proteinuria. Which of the following is true for this type of hypertension?
In the past, there was concern that rigorous drug treatment would harm the fetus. Studies now show benefit in controlling pressure with drugs, but ACE inhibitors are contraindicated because they might cause renal abnormalities in the fetus. Women who develop hypertension during pregnancy have a higher risk of developing hypertension in later life.
A 61-year-old man has a non-ST-elevation MI and is admitted to the coronary care unit. The following day, he develops bradycardia but no symptoms. His blood pressure is 126/84 mm Hg, pulse 50/min, and on examination, the heart sounds are normal, with no extra sounds or rubs. His ECG has changed. Which of the following ECG findings is the best indication for this patient to receive a pacemaker?
There is a possible indication (but not an obligation) to insert a temporary pacemaker if a new LBBB occurs. If LBBB and a Mobitz type II AV block occur, there is general agreement on the usefulness of pacing. Temporary pacemaker is not required for first-degree block. For second-degree block of the Wenckebach type (usually with an inferior infarction), pacing is only required if symptoms of bradycardia and hypotension cannot be controlled medically. The necessity for temporary pacing during an acute myocardial infarction (AMI) does not necessarily indicate that permanent pacing will be required.
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Auscultation of the heart of a 17-year-old boy reveals an increased intensity of the pulmonary component of the second heart sound. He complains of dyspnea on exertion but no other cardiac or pulmonary symptoms. Which of the following explanations is the most likely cause of his dyspnea?
Pulmonary hypertension is associated with an increased intensity of the second heart sound, which coincides with the end of the T wave on ECG. It is the pulmonic component of the second heart sound that is increased. Pulmonary stenosis can cause dyspnea on exertion but auscultation will reveal a systolic murmur and decreased second heart sound (pulmonic component). As well, there may be prominent a waves in the jugular venous pulse, a right ventricular heave, an ejection click, and a right ventricular fourth heart sound. When signs and symptoms are apparent, the pulmonary hypertension is usually moderate to severe.
A 22-year-old woman complains of palpitations and has a regular heartbeat at a rate of 170/min, with a blood pressure of 110/70 mm Hg. The rate abruptly changes to 75/min after applying carotid sinus pressure. Which of the following is the most likely diagnosis?
The patient most likely has PSVT, since the tachycardia terminates after carotid sinus massage (CSM). CSM increases vagal tone (parasympathetic) which decreases AV nodal conduction and terminates AV node re-entry arrhythmias. Sinus tachycardia differs from PSVT tachycardia in that it does not start or stop abruptly. In PSVT, the QRS is usually narrow without clearly discernible P waves. A wide QRS in PSVT can result from a preexisting bundle branch block, or a functional bundle branch block secondary to the tachycardia. This can make the distinction from a ventricular arrhythmia quite difficult.
A 73-year-old man has angina pectoris on exertion, but an angiogram reveals noncritical stenosis of the coronary arteries. This occurs most frequently with which of the following valvular heart diseases?
In the absence of critical CAD, angina pectoris occurs most frequently with aortic stenosis. AMI is usually due to associated atherosclerotic coronary occlusion.
A patient with new-onset syncope has a blood pressure of 110/95 mm Hg and a harsh systolic ejection murmur at the base, radiating to both carotids. Auscultation of the second heart sound at the base might reveal which of the following findings?
In aortic stenosis, the first sound is usually normal; the second sound is characteristically diminished because of the increased ventricular pressure and the stenotic valve is less mobile. There can be a single S2 either because A2 and P2 are superimposed or A2 is absent or very soft. Severe aortic stenosis may be accompanied by paradoxical splitting of S2.
A 69-year-old woman complains of easy fatigue and one episode of presyncope. On examination of the jugular venous pressure (JVP), there are irregular large a waves. The ECG has fixed PP and RR intervals but varying PR intervals. Which of the following conditions is this most likely caused by?
AV dissociation is the independent beating of atria and ventricles and is recognized on the ECG by fixed PP and RR intervals but variable PR intervals. AV block is one cause of AV dissociation
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A 57-year-old man has an anterior MI. It is complicated by the development of heart failure. Nitroglycerin would be a useful first medication under which circumstances?
Nitroglycerine is usually used in the setting of severe pulmonary congestion with adequate blood pressure. With significant hypotension, inotropic agents are generally administered prior to nitroglycerine
A 28-year-old man develops viridans group streptococci septicemia. Which of the following cardiac lesions has the highest risk of developing endocarditis?
Aventricular septal defect is considered a relatively high-risk lesion for infective endocarditis. Mitral valve prolapse with regurgitation, asymmetric septal hypertrophy, and pure mitral stenosis are considered an intermediate risk. Atrial septal defects of the secundum type are considered low risk.
A 47-year-old woman has new-onset transient right arm weakness and word finding difficulty symptoms lasting 3 hours. She is also experiencing exertional dyspnea, and had a syncopal event 1 month ago. Her echocardiogram reveals a cardiac tumor in the left atrium, it is pendunculated and attached to the endocardium. Which of the following is the most likely cause of this lesion?
The myxoma is a solitary globular or polypoid tumor varying in size from that of a cherry to a peach. About 75% are found in the left atrium, and most of the remainder in the right atrium. The clinical presentation is with one or more of the classical triad of constitution symptoms (fatigue, fever, anemia), embolic events, or obstruction of the valve orifice.
A 72-year-old woman has new-onset atrial flutter with a ventricular rate of 150/min. She is hemodynamically stable with a blood pressure of 155/90 mm Hg, but is experiencing palpitations. Which of the following drugs is the best intravenous choice for controlling the heart rate?
Diltiazem and verapamil may be of help in both acute paroxysms of atrial flutter and chronic management. The other choices have no effect on the AV node to slow down flutter, and atropine accelerates AV conduction. At times, catheter ablation of the flutter pathway is required in chronic atrial flutter. Surgical ablation is reserved for cases where other surgical interventions are required.
Several of the older patients in your practice intend to pursue exercise programs. They have no cardiac symptoms, but some do have vascular risk factors such as diabetes or hypertension. In these patients, which of the following is true about exercise electrocardiography?
Please select 2 correct answers
Exercise electrocardiography represents an increasingly popular noninvasive method for early detection of latent ischemic heart disease. As with other diagnostic tests, the exercise ECG is of most clinical value when the pretest probability of disease is moderate (i.e., 30–70%). In men over 40 and women over 50 who plan to start vigorous exercise, use of exercise ECG is possibly, but not definitely, supported by the evidence (class IIb).
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