MOC Questions

Cardiology Review® Online, June 2008, Volume 25, Issue 6

Preparing for the American Board of Internal Medicine Maintenance of Certification

The following questions can assist candidates for the Maintenance of Certification Exam in Cardiovascular Disease prepare for this test. We hope you find this helpful and welcome your feedback.

These questions were prepared by Hal A. Skopicki, MD, PhD.

Questions

  1. In heart failure, all of the following are activated by a decrease in cardiac output and serve as counterregulatory mechanisms that try to maintain end-organ perfusion, EXCEPT: Release of plasma renin, angiotensin II, and aldosterone. Tachycardia and ventricular dilation. Increase in systemic vascular resistance. Sodium and volume retention. TNF α and PGI2 release.

  1. All of the following statements about cardiovascular physical examinations are true, EXCEPT: Rales in patients with chronic heart failure have a low sensitivity, high specificity, low negative predictive value, and high positive predictive value for detecting concomitant elevated pulmonary capillary wedge pressure. Jugular venous distension has been associated with a low sensitivity and a high specificity for suggesting elevated left ventricular filling. Jugular venous distension has been associated with a low negative predictive value and a high positive predictive value for detecting left ventricular dysfunction in patients undergoing cardiac catheterization for dyspnea or chest pain. The presence of jugular venous distension in symptomatic patients with left ventricular dysfunction is associated with an increased risk of hospitalization for heart failure and death from progressive pump failure. Rales and peripheral edema are present in 75% of patients admitted to the hospital for acutely decompensated heart failure.

  1. Which patient would gain the most from an implantable cardioverter defibrillator (ICD)? A 33-year-old woman who is found to have right ventricular outflow tract tachycardia on a 12-lead electrocardiogram. A 68-year-old patient who sustained an inferior wall myocardial infarction (MI) 12 years earlier and is recently found to have a left ventricular ejection fraction (LVEF) of 0.28 on echocardiography despite receiving maximal medical therapy. A 71-year-old woman who has class II heart failure and an LVEF of 0.46. Her medical history includes VT arrest upon reperfusion of an anterior wall MI. A 22-year-old woman with a mutation in her SCNA gene and a family history of Brugada syndrome in her brother. A patient with hypertrophic cardiomyopathy (myosin heavy chain mutation) and a left ventricular outflow tract gradient of 14 mm Hg during exercise.

  1. Which of the following guidelines for driving are indicated for patients who have received an implantable cardioverter defibrillator (ICD)? Patients who receive ICDs for primary prevention should avoid driving for at least 4 weeks after ICD implantation. Although their driving is not restricted after this period, they should be informed that loss of consciousness is possible. Once an ICD delivers appropriate therapy for ventricular tachycardia (VT) or ventricular fibrillation (VF), the patient should not be allowed to drive again. Once an ICD delivers appropriate therapy for VT or VF, those implanted with an ICD should be allowed to drive again if placed on antiarrhythmic medication. After an episode of VF or sustained VT that leads to implantation of an ICD, a patient may be allowed to drive after 3 months if there is no evidence of recurrence and ICD firing. Compared with guidelines for noncommercial motorists, the primary- and secondary-prevention driving guidelines for commercial vehicles generally require longer intervals after ICD placement and without documented events before driving can resume.

  1. You are asked to consult on the case of a 24-year-old woman who died suddenly while participating in a swimming competition and was successfully defibrillated in the field. She is found to have a prolonged QTc interval on an electrocardiogram. All of the following statements about long QT (LQT) syndrome are true, EXCEPT: Patients with LQT1 usually have cardiac events preceded by exercise or swimming. LQT2 is associated with an arrhythmic event after an emotional event or exposure to an auditory stimulus. Patients with LQT3 have defective potassium channel opening. LQT syndrome associated with congenital deafness may indicate the presence of Jervell and Lang-Nielsen syndrome. LQT syndrome associated with skeletal abnormalities, such as short stature and scoliosis, may be present in LQT7 (Andersen’s syndrome).

  1. All of the following statements about the inherited forms of long QT (LQT) syndrome are true, EXCEPT: LQT1 and Jervell and Lang-Nielsen syndrome (JLN1-2) are associated with mutations of the KCNQ1 (KVLQT1) gene, and LQT5 is associated with mutations of the KCNE1 gene; all of these syndromes affect the potassium. LQT2 is associated with mutations of the HERG (KCNH2) gene while LQT6 is associated with mutations of the MiRP1 (KNCE2) gene; both of these syndromes affect the potassium IKr. LQT3 is associated with a gain of function mutation of the sodium channel SCN5A. LQT4 is associated with mutations of the ANK2 (ANKB) gene that affects sodium, potassium, and calcium currents. QT prolongation usually occurs secondary to defects in calcium channel function.

  1. Congenital long QT (LQT) syndrome may be associated with all of the following, EXCEPT: Prolongation of the QT interval, torsade de pointes, and T-wave alternans. Persistent hypokalemia and hypomagnesemia. Wide-based T waves that are most frequently seen in LQT1 syndrome. Notched T waves that are most commonly seen in LQT2 syndrome. T waves that appear normal with a long, isoelectric ST segment that is usually seen in LQT3 syndrome.

  1. Which of the following statements concerning hypertrophic cardiomyopathy with LV outflow obstruction is TRUE? Outflow tract obstruction can be increased with exercise, moving from squatting to standing, and with the Valsalva maneuver. Outflow tract obstruction is increased with isometric handgrip. Diastolic anterior motion of the mitral leaflet with mid-diastolic contact of the ventricular septum contributes to the functional obstruction. alpha blockers and disopyramide worsen the obstruction by decreasing myocardial contractility. Successful alcohol ablation in obstructive hypertrophic cardiomyopathy eliminates the risk of sudden death.

  1. A 72-year-old woman with left lower extremity leg swelling is referred to you by her family practitioner. A previous workup demonstrates a normal duplex venous ultrasound and a normal D-dimer level. She notes that although her legs have always been a little large, her left leg has been a bit swollen recently, which is more noticeable at the end of the day and improves slightly upon raising her legs. She reports no shortness of breath with exertion, orthopnea, or paroxysmal nocturnal dyspnea. Physical examination reveals a blood pressure of 108/80 mm Hg, a regular heart rate of 72 beats per minute (bpm), and an unlabored respiratory rate of 16 breaths per minute. Her neck veins are flat and no hepatojugular reflex (HJR) is present. She is able to lie flat on the examining table for more than 10 minutes. The patient has left leg pitting edema to the mid thigh, which involves her ankle, foot, and toes that appear square. No skin breakdown is present. Echocardiography reveals mild concentric left ventricular hypertrophy, and Grade I diastolic dysfunction without left atrial enlargement or right ventricular dysfunction. Which of the following would be the next best step in evaluating the patient? Cardiac catheterization to assess occult ventricular dysfunction. Cardiac magnetic resonance imaging (MRI) to assess right ventricular function. Lymphoscintigraphy to rule out lipoedema. Abdominal and pelvic ultrasonography or computed tomography. Lower extremity vascular flow studies.

  1. You are asked to consult on the case of a 36-year-old woman with increasing shortness of breath. The patient underwent cardiac transplantation 5 years earlier due to intractable heart failure associated with peripartum cardiomyopathy. She had an uncomplicated post-transplant course, but experienced a few episodes of Grade I rejection. A cardiac biopsy 3 months earlier showed no rejection. The patient’s immunosuppressive regimen included cyclosporin and mycophenolate mofetil. She reports dyspnea on exertion that has progressed over the past 6 to 8 months. A computed tomography (CT) scan of the chest 2 weeks earlier was unremarkable. On physical examination, she has a blood pressure of 155/76 mm Hg, a regular pulse at 92 beats per minute, and an unlabored respiratory rate of 23 breaths per minute. She is afebrile and has no jugular venous distension, but bibasilar rales are present. She has a clearly audible S4, but no murmurs are discernable despite provocative maneuvers. Her electrocardiogram (ECG) reveals normal sinus rhythm, an incomplete right bundle branch block that is unchanged from her previous ECG, and a questionable new repolarization abnormality in leads II, III, and aVF. An echocardiogram reveals mild general left ventricular hypokinesis and no valvular abnormalities. Cardiac enzymes and serum B-type natriuretic peptide are unremarkable. You suggest: CT scanning to rule out an opportunistic pulmonary infection. Cardiac biopsy to rule out cardiac allograft rejection. Cardiac biopsy and coronary angiography to rule out transplant atherosclerosis. Exercise and stress reduction and provide reassurance. Transthoracic echocardiography to rule out endocarditis.

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Answers

1: E

Multiple neurohormones are activated in response to a decrease in cardiac output due to heart failure. The formulation of the neurohormonal hypothesis has been supported by multiple clinical trials demonstrating the favorable effects of neurohormonal antagonists (β-blockers, angiotensin-converting enzyme inhibitors, and aldosterone antagonists). Moreover, the degree of activation of these antagonists has been associated with patient survival. The inflammatory state present in heart failure has been linked to increased circulating levels of several cytokines, especially TNF α and PGI2, both of which are vasodilatory in nature. Data from several studies have shown that these cytokine levels increase as functional capacity deteriorates; thus, it is surprising that TNF α inhibition so far has failed to alter the natural history of congestive heart failure.

Sources

Circulation

Packer M. Neurohormonal interactions and adaptations in congestive heart failure. . 1988;77(4):721-730.

J Am Coll Cardiol

Benedict CR, Johnstone ED, Weiner DH, et al, for the SOLVD investigators. Relation of neurohumoral activation to clinical variables and degree of ventricular dysfunction: a report from the registry of studies of left ventricular dysfunction. . 1994;23(6):1410-1420.

Circulation

Francis GS, Benedict C, Johnstone DE, et al, for the SOLVD investigators. Comparison of neuroendocrine activation in patients with left ventricular dysfunction with and without congestive heart failure. A substudy of the Studies of Left Ventricular Dysfunction (SOLVD). . 1990; 82(5):1724-1729.

Circulation

Swedberg K, Eneroth P, Kjekshus K, et al. Hormones regulating cardiovascular function in patients with severe congestive heart failure. . 1990;82(5):1730-1736.

N Engl J Med

Levine B, Kalman J, Mayer L, et al. Elevated circulating levels of TNF in severe chronic heart failure. . 1990;323(4):236-241.

Circulation

Deswal A, Bozkurt B, Seta Y, et al. Safety and efficacy of a soluble P75 tumor necrosis factor receptor (Enbrel, etanercept) in patients with advanced heart failure. . 1999;99(25):3224-3226.

Int J Cardiol

Anker SD, Coats AJ. How to RECOVER from RENAISSANCE? The significance of the results of RECOVER, RENAISSANCE, RENEWAL, and ATTACH. . 2002;86(2-3):123-130.

2: E

In the setting of chronic heart failure, there are strong correlations between the detection of rales or the presence of jugular venous distension and the presence of an elevated left ventricular filling pressure. Confounding issues include body habitus along with intervening right ventricular dysfunction, pulmonary hypertension, and tricuspid valve disease. Despite these challenges, a retrospective analysis of the Studies of Left Ventricular Dysfunction (SOLVD) treatment trial showed an elevated risk of heart failure hospitalization (relative risk [RR] 1.32; 95% confidence interval [CI], 1.08-1.62; P < .01), death or hospitalization for heart failure (RR 1.30; 95% CI; 1.11-1.52; P < .005), and death from pump failure (RR 1.37; 95% CI, 1.07-1.75; P < .05) in patients with elevated jugular venous distension. A multitude of studies of patients with heart failure and volume overload showed that rales (sensitivity, 60%-80%) and peripheral edema (sensitivity, 20%-50%) may be absent; thus, a patient’s entire clinical picture must be considered.

Sources

JAMA

Stevenson LW, Perloff JK. The limited reliability of physical signs for estimating hemodynamics in chronic heart failure. . 1989;261(6): 884-888.

J Am Coll Cardiol

Butman SM, Ewy GA, Standen JR, et al. Bedside cardiovascular examination in patients with severe chronic heart failure: importance of rest or inducible jugular venous distension. . 1993;22(4): 968-974.

Congest Heart Fail

Rame JE, Dries DL, Drazner MH. The prognostic value of the physical examination in patients with chronic heart failure. . 2003;9(3):170-5, 178.

Am J Med

Drazner MH, Rame JE, Dries DL. Third heart sound and elevated jugular venous pressure as markers of the subsequent development of heart failure in patients with asymptomatic left ventricular dysfunction. . 2003;114(6):431-437.

3: B

ICDs improve survival in patients with a history of life-threatening ventricular arrhythmias. Several recent trials have shown that ICDs also serve as primary prophylaxis against sudden cardiac death in patients at high risk for ventricular arrhythmias; this includes patients with LVEF 0.35 and New York Heart Association class II or III heart failure as well as patients with a history of MI and LVEF of < 0.30. Other class IA indications for ICD implantation include cardiac arrest due to ventricular fibrillation or ventricular tachycardia not due to a transient or reversible cause; nonsustained VT in patients with coronary artery disease; a prior MI; left ventricular dysfunction; and inducible VF or sustained VT at electrophysiologic study that is not suppressible by a class I antiarrhythmic agent. Class IB indications include spontaneous sustained VT in association with structural heart disease; syncope of undetermined origin with clinically relevant, hemodynamically significant sustained VT; or VF induced at electrophysiologic study when drug therapy is ineffective, not tolerated, or not preferred. Although the future promise of genetic testing is great, it is currently rudimentary and the findings are difficult to apply in practice.

Sources

Circulation.

Schoenfeld MH. Contemporary pacemaker and defibrillator device therapy: challenges confronting the general cardiologist. 2007; 115(5):638-653.

4: E

Recommendations for ventricular tachyarrhythmias do not specifically target patients with ICDs. Rather, they target the risk of arrhythmia recurrence and, in the event of recurrence, the risk of syncope or loss of control. Patients who receive ICDs for primary prevention should avoid driving for at least 1 week after ICD placement and should then be informed that loss of consciousness is possible while driving. After an episode of VT following implantation of an ICD, a patient could be allowed to drive after 6 months without documented VT and ICD firing. Because the consequences of VT complications can be disasterous for commercial drivers and airline pilots, the driving guidelines for such patients with primary- and secondary-prevention ICDs are stricter. The Canadian Cardiovascular Society Consensus Conference defined a private driver as one who drives fewer than 36,000 km or spends less than 720 hours behind the wheel annually, drives a vehicle weighing less than 11,000 kg, and does not earn a living by driving.

Sources

Circulation.

Epstein AE, Baessler CA, Curtis AB, et al. Addendum to “Personal and public safety issues related to arrhythmias that may affect consciousness: Implications for regulation and physician recommendations: A medical/ scientific statement from the American Heart Association and the North American Society of Pacing and Electrophysiology.” Public safety issues in patients with implantable defibrillators. A scientific statement from the American Heart Association and the Heart Rhythm Society. 2007;115(9):1170-1176.

Circulation

Epstein AE, Miles WM, Benditt DG, et al. Personal and public safety issues related to arrhythmias that may affect consciousness: implications for regulation and physician recommendations. A medical/scientific statement from the American Heart Association and the North American Society of Pacing and Electrophysiology. . 1996;94(5):1147-1166.

J Am Coll Cardiol.

Grubb BP. Driving and implantable cardioverter-defibrillators. A clearer view. 2007;50(23):2241-2242.

Can J Cardiol.

Consensus Conference, Canadian Cardiovascular Society. Assessment of the cardiac patient for fitness to drive. 1992,8(4):406-419.

5: C

QT intervals corrected (QTc) for a heart rate longer than 0.44 seconds are generally considered abnormal, although a normal QTc can be slightly prolonged in women (up to 0.46 sec). The Bazett equation is used to calculate the QTc: QTc = QT/root of the R-R interval. In LQT syndrome, QT prolongation is due to overload of myocardial cells with positively charged ions during ventricular repolarization. Morphology may be illustrative. LQT1 is characterized by a broad-based T wave, while LQT3 shows a prolongation of the QT interval caused by stretching of the ST segment followed by a narrow and peaked T wave. Individuals with the LQT1 genotype experience about 90% of their fainting events during physical activity. LQT2 syndrome is associated with an arrhythmic event after an emotional event or exposure to an auditory stimulus (eg, doorbells, telephone ring, etc). Patients with LQT3 usually experience events during nighttime sleep. The LQT7 gene encodes for an inward repolarizing of current protein found in both cardiac and skeletal muscle, resulting in concomitant skeletal abnormalities, such as short stature or scoliosis. Those with an abnormal LQT gene but without a prolonged QT interval may also have an increased risk of sudden death.

Sources

N Engl J Med

Priori SG, Schwartz PJ, Napolitano C, et al. Risk stratification in the long- QT syndrome. . 2003;348(19):1866-1874.

J Electrocardiol.

Ackerman MJ. Genotype-phenotype relationships in congenital long QT syndrome. 2005;38(4 suppl):64-68.

J Cardiovasc Med.

Napolitano C, Bloise R, Priori SG. Long QT syndrome and short QT syndrome: how to make correct diagnosis and what about eligibility for sports activity. 2006;7(4):250-256.

6: E

Genetic testing for known mutations in deoxyribonucleic acid (DNA) samples from patients is becoming accessible. Although identification of an LQT syndrome genetic mutation confirms the diagnosis, a negative result may be of limited diagnostic value because it is estimated that fewer than 50% of patients with LQT syndrome have known mutations. The three most common forms of long QT syndrome are LQT1, LQT2 (both potassium channel gene mutations), and LQT3 (a sodium channel gene mutation). In LQT3 syndrome, caused by mutations of the SCN5A gene for the sodium channel, a gain-of-function mutation causes persistent inward sodium current in the plateau phase, which contributes to prolonged repolarization. Jervell and Lang-Nielsen syndrome has been associated with two gene defects (KVLQT1 or KCNE1), which affect the potassium IKs channel. It is important to review the electrocardiograms (ECGs) of family members of a patient with LQT syndrome so that detailed histories of sudden blackouts or fainting can be obtained; however, an absence of ECG findings of the syndrome in family members does not rule out the presence of LQT syndrome in these individuals.

Sources

Expert Rev Mol Diagn.

Ching CK, Tan EC. Congenital long QT syndromes: clinical features, molecular genetics, and genetic testing. 2006; 6(3):365-374.

Genet Med.

Modell SM, Lehmann MH. The long QT syndrome family of cardiac ion channelopathies: a HuGE review. 2006;8(3):143-155.

J Electrocardiol.

Lankipalli RS, Zhu T, Guo D, et al. Mechanisms underlying arrhythmogenesis in long QT syndrome. 2005;38(4 suppl):69-73.

7: B

Hypokalemia and hypomagnesemia are secondary causes of QT prolongation and repolarization abnormalities. In LQT syndrome, QT prolongation is due to overload of myocardial cells with positively charged ions during ventricular repolarization. In LQT1, LQT2, LQT5, LQT6, and LQT7, potassium ion channels are blocked, are opened with a delay, or are open for a shorter period than they are in normally functioning channels. These changes decrease the potassium outward current and prolong repolarization. LQT1 is characterized by a broad-based T wave, while LQT3 shows a prolongation of the QT interval caused by stretching of the ST segment, which is followed by a narrow and peaked T wave. LQT1 gene defects result in abnormalities of IKs and the slowly deactivating, delayed rectifier potassium channel, resulting in decreased outward potassium current and channels remaining open longer than usual, delaying ventricular repolarization. LQT2 gene mutations result in an abnormal IKr and in the rapidly activating, rapidly deactivating, delayed rectifier potassium channel, causing rapid closure of the potassium channels and a decrease in the normal rise in IKr. LQT3 syndrome, caused by gain-of-function mutations of the SCN5A gene encoding the sodium channel, results in persistent inward sodium current in the plateau phase, which contributes to prolonged repolarization. Loss-of-function mutations in the same gene may lead to Brugada syndrome. LQT1 carriers usually have broad-based T waves, LQT2 carriers show low-amplitude T waves with high incidence of notches, and LQT3 carriers frequently have an extended ST segment with a relatively narrow peaked T wave.

Sources

Circulation.

Moss AJ, Zareba W, Benhorin J, et al. ECG T-wave patterns in genetically distinct forms of the hereditary long QT syndrome. 1995;92(10):2929-2934.

J Cardiovasc Electrophysiol.

Antzelevitch C. Molecular genetics of arrhythmias and cardiovascular conditions associated with arrhythmias. 2003;14(11):1259-1272.

8: A

Left ventricular outflow tract obstruction is due to systolic anterior motion of the mitral leaflet. Interventions that decrease myocardial contractility (eg, â-blockers and disopyramide) can reduce the obstruction, whereas obstruction can be increased with augmentation of contractility (exercise) or when there is a decreases in ventricular volume (eg, during the strain phase of the Valsalva maneuver and moving from squatting to standing). In a single-center study that provides the largest available database on survival after alcohol ablation of the septum secondary to hypertrophic obstructive cardiomyopathy, in-hospital mortality rates were low, but the risk of sudden death was not completely eliminated.

Sources

Clin Res Cardiol.

Kuhn H, Lawrenz T, Lieder F, et al. Survival after transcoronary ablation of septal hypertrophy in hypertrophic obstructive cardiomyopathy (TASH): a 10-year experience. 2008;97(4):234-243.

Nat Clin Pract Cardiovasc Med.

Miller MA, Gomes JA, Fuster V. Risk stratification of sudden cardiac death in hypertrophic cardiomyopathy. 2007;4(12):667-676.

N Engl J Med.

Lembo NJ, Dell’Italia LJ, Crawford MH, et al. Bedside diagnosis of systolic murmurs. 1988;318(24):1572-1578.

9: D

The absence of dyspnea and the results of the echocardiogram strongly suggest that cardiac etiologies, specifically left ventricular systolic or diastolic dysfunction, are not the cause. While right ventricular dysfunction may be present despite a normal echocardiogram due to incomplete imaging of the right ventricle, there is no elevated jugular venous distension, abdominal distention, or hepatojugular reflex is absent. The unilateral nature of the swelling argues against hepatic vein thrombosis or higher intravascular tumor invasion. Lipidema is a nonpainful and chronic infiltration of the leg with fatty deposits. It is marked by the absence of foot involvement and no change in symptoms after leg elevation. A limited MRI can demonstrate the fatty infiltration. Lower extremity swelling with foot and toe involvement that results in “toe-squaring” is characteristic of lymphedema. The overlying skin takes on a waxy texture with peau d’orange changes and skin thickening. While compression is the treatment of choice, in the absence of congenital or traumatic causes, lymph node compression due to cancer should be considered.

Source

Am Fam Physician.

Powell AA, Armstrong MA. Peripheral edema. 1997;55(5):1721-1726.

10: C

Transplant vasculopathy is the single most important factor limiting long-term functioning of solid organ allografts. Fifty percent of transplant recipients will have significant disease within 5 years of transplantation, and 90% will have significant vasculopathy within 10 years. Although immunosuppressive agents counter acute allograft rejection, they do not alter the natural history of transplant vasculopathy. The vasculopathy presents with diffuse, intimal, and hyperplastic lesions that lead to ischemic graft failure; thus, retransplantation is often required. Transplanted hearts are denervated so angina pectoris may not be present. While risk factors such as obesity, diabetes, and hypertension should continue to be managed aggressively, transplant atherosclerosis occurs independent of the usual coronary risk factors and increases over time after transplantation. While organ rejection or opportunistic infection are possible, they are less likely.

Sources

Heart Fail Clin.

Sipahi I, Starling RC. Cardiac allograft vasculopathy: an update. 2007;3(1):87-95.

Circ Res.

Mitchell RN, Libby P. Vascular remodeling in transplant vasculopathy. 2007;100(7):967-978.