Cardiovascular Flashcards
(143 cards)
1
Q
What is the most likely diagnosis?
A
Abdominal aortic aneurysm (AAA).
2
Q
What are the major branches of the aorta below the diaphragm?
A
Blood flow to the major organs is of special concern with an AAA. The inferior phrenic arteries, celiac trunk, middle suprarenal arteries, renal arteries, superior mesenteric artery, testicular arteries, inferior mesenteric artery, lumbar arteries, and the common iliac arteries are located below the diaphragm.
3
Q
What is the three-layer composition of muscular arteries?
A
4
Q
An increased risk of AAA is associated with defects in the genes coding for which proteins?
A
5
Q
Once the aortic wall is disrupted in AAA, how does coagulation proceed?
A
6
Q
What are the risk factors for AAA?
A
7
Q
What are the treatment options for AAA?
A
8
Q
What is the most likely diagnosis?
A
Aortic stenosis.
9
Q
What factors increase the risk of Aortic stenosis?
A
10
Q
What type of murmur is caused by Aortic Stenosis?
A
11
Q
How is Aortic Stenosis associated with congestive heart failure (CHF)?
A
12
Q
What complications are associated with Aortic Stenosis?
A
13
Q
What is the appropriate treatment for Aortic Stenosis?
A
14
Q
What is the most likely diagnosis?
A
15
Q
What risk factors increase a person’s likelihood of developing Stable angina?
A
16
Q
What is the pathophysiology of stable angina?
A
Endothelial injury resulting from various factors, including hyperlipidemia, smoking, and hypertension, can lead to monocytic and lipid infiltrates into the subendothelium (fatty streaks), release of growth factors leading to smooth muscle cell proliferation into the intima (proliferative plaque), and subsequent development of foam cells and complex atheromas with calcification and ischemia of the intima.
17
Q
Which arteries are most commonly affected in stable angina?
A
Atherosclerosis preferentially affects the branching points of arteries or areas of turbulent blood flow including the proximal coronary arteries, popliteal arteries, renal arteries, carotid arteries, and arteries of the circle of Willis.
18
Q
What complications are commonly associated with stable angina?
A
In addition to angina, other complications of atherosclerotic injury include aneurysms, myocardial infarction, stroke, ischemia, and ischemic bowel disease.
19
Q
What are the 3 major forms of angina?
A
1. Stable angina: Chest pain with exertion; responds to nitroglycerin.
2. Unstable angina: Chest pain at rest secondary to thrombus in a branch. May not completely respond to
nitroglycerin; antithrombic agents and heparin may also be required.
3. Prinzmetal angina: Chest pain at rest, secondary to coronary artery spasm. Treatment includes calcium
channel blockers.
20
Q
What is the likely diagnosis?
A
Atrial fibrillation.
21
Q
What clinical and electrocardiographic abnormalities are commonly associated with AF?
A
Lightheadedness, palpitations, anxiety, pallor, and diaphoresis are commonly associated with atrial fibrillation. Likewise, as in this patient, heart rate is elevated and borderline hypotension is possible. Electrocardiogram (ECG) shows an absence of P waves, irregular R-R intervals, and tachycardia, as in this patient. Irregularly irregular uncoordinated atrial contractions can lead to tachycardia and stasis of blood in the left atrium; the development of clot within the heart often ensues.
22
Q
What is the appropriate treatment for AF?
A
23
Q
How do heparin and warfarin work together to treat AF?
A
Given intravenously, heparin activates antithrombin III. Its effectiveness is determined by partial thromboplastin time (which reflects activity of the intrinsic pathway). Given orally, warfarin impairs the synthesis of vitamin K–dependent clotting factors (II, VII, IX, and X). It is monitored by prothrombin time (extrinsic pathway).
24
Q
Why does paradoxical coagulation sometimes occur after starting warfarin therapy?
A
Warfarin also inhibits the synthesis of protein C and protein S. Because proteins C and S inhibit factors Va and VIIIa, a deficiency in these proteins promotes coagulation.
25
What is the most likely diagnosis?
Cardiac myxoma of the left atrium. Most myxomas arise from the mural endocardium and measure 1–15 cm.
26
What is the epidemiology of Cardiac myxoma?
Primary tumors of the heart are rare. Myxomas account for approximately 50% of benign tumors in the heart. The majority (75%) are located in the left atrium, although all chambers can be affected. The typical age of onset is 30–60 years. Familial occurrences have been reported in approximately 5% of cases via autosomal dominant transmission. These are associated with a younger age of presentation and higher rates of recurrence.
27
What are 3 complications of left atrial myxomas?
Complications from left atrial myxomas can be categorized as follows:
1. Embolization occurs in 40%–50% of cases with tumor fragments lodging in distal organs (eg, brain, heart, or extremities).
2. Infection is rare but may lead to further complications with embolization.
3. Obstruction of the mitral or pulmonary venous orifices may occur, resulting in pulmonary hypertension
and right heart failure.
28
How can the results of the cardiac examination be explained?
Splitting of S1 is accentuated as the tumor is extruded from the mitral orifice. P2 can also be louder if the tumor obstructs the mitral orifice or pulmonary venous return. The third heart sound is produced by the tumor “plopping” within the atrium during diastole.
29
What pathology does the ECG in Figure 5-5 depict?
Second-degree atrioventricular (AV) block type I, also known as Mobitz type I block or Wenckebach block. Progressive lengthening of the PR interval from one beat to the next is seen until finally a beat is dropped (a P wave is not followed by a QRS complex).
30
What is the pathophysiology of Mobitz type I block (Wenckebach block)?
Second-degree AV block type I occurs secondary to impaired conduction at the level of the AV node, such that atrial impulses fail to reach the ventricles. Given the location of the patient’s prior MI, it is possible that it may have compromised the conductive ability of his AV node. An MI involving the right coronary artery may disrupt blood supply to the sinoatrial [SA] node and atrioventricular [AV] node. By contrast, involvement of the left anterior descending coronary artery causes infarction of the His-Purkinje system.
31
How is Heart Block classified?
32
What is the appropriate treatment for Mobitz type I block (Wenckebach block)?
Often, no treatment is necessary in asymptomatic patients with a second-degree Mobitz type I block. In symptomatic patients, atropine or isoproterenol may be used, or a pacemaker may be required.
33
What is the most likely diagnosis?
Coarctation of the aorta occurs two to five times more often in males than in females.
34
In Coarctation of the aorta, which part of the aorta is typically affected?
35
What is the characteristic finding on physical examination in patient's with coarctation of the aorta?
Auscultation over the chest and/or back may reveal a midsystolic ejection murmur. A continuous murmur over the chest may also be heard in older individuals who have developed collateral circulation. Weak, delayed pulses in the lower extremities are also characteristic of coarctation.
36
What chromosomal abnormality is associated with Coarctation of the aorta?
Coarctation of the aorta is associated with Turner syndrome (45,XO).
37
What findings on physical examination, ECG, and x-ray of the chest often develop over time in patients with Coarctation of the aorta?
38
What is the most likely diagnosis?
This constellation of clinical findings, including cardiac manifestations, a “blueberry muffin” rash, and the maternal history strongly suggest congenital rubella syndrome (CRS). Rubella virus (RV) is an RNA virus of the Togaviridae family, and it is associated with an 85% risk of congenital defects if acquired in the first 12 weeks of pregnancy. Other infections acquired in utero that can present with rash and ocular findings can be recalled with the ToRCHeS acronym: Toxoplasmosis, other infections, Rubella, Cytomegalovirus infection, Herpes simplex, and Syphilis.
39
What laboratory test in the neonate can help confirm this diagnosis?
Congenital Rubella Syndrome (CRS)
40
What laboratory test in the neonate can help confirm the diagnosis of congenital rubella syndrome?
Viral culture of nasal secretions or monthly serology testing for anti-rubella IgM antibody with rising titers can establish a laboratory CRS diagnosis.
41
What cardiac anomalies are associated with the murmur seen in this patient?
42
What other symptoms are common in patients with congenital rubella syndrome (CRS)?
Primary rubella infection early in pregnancy results in defective organogenesis. The classic permanent abnormalities include cataracts, retinopathy, heart defects, and sensorineural deafness. Transient abnormalities include meningoencephalitis, thrombocytopenia with or without purpura, and bony radiolucencies. Since CRS is a persistent infection, more abnormalities, such as developmental difficulties and progressive panencephalitis, can occur.
43
What is the appropriate treatment for congenital rubella syndrome (CRS)?
Since no therapy currently exists for CRS, the focus is on prevention through vaccination. Rubella vaccine contains live, attenuated rubella virus and therefore is contraindicated in pregnant women. Rubella has been eliminated in the United States and Scandinavia but persists elsewhere because of inadequate vaccination programs.
44
Which area of the heart is affected by this obstruction?
The LAD runs along the anterior interventricular (IV) groove and supplies the anterior right and left ventricles as well as the anterior IV septum. The LAD is the most common coronary artery to become occluded.
45
From what vessel does the LAD originate?
The left main artery bifurcates, in most people, to the LAD and the circumflex artery (Figure 5-9).
46
What are the branches of the right coronary artery (RCA), and what territories do they supply?
The RCA first travels in the atrioventricular (AV) groove then wraps around the inferior border of the heart to the posterior IV groove. In 80% of people, the SA nodal artery is the first branch of the RCA. Other branches of the RCA include the right marginal, posterior descending (in 80% of people) and AV nodal arteries.
47
During which part of the contraction cycle do coronary arteries fill?
The coronary arteries have maximal blood flow during diastole and minimal flow during systole. This is due to their location above the cusps of the aortic valve, which obstructs flow into the coronary arteries when the valve opens during systole.
48
What biomarkers indicate myocardial injury?
Creatine kinase (CK) is an enzyme that is found in muscle tissue throughout the body and may become elevated from damage to muscle cells. Elevated CK levels are not specific to myocardial infarction (MI) and may be seem in rhabdomyolysis, myocarditis, and myositis. CK-MB is an isoenzyme of CK that is expressed in higher levels in cardiac muscle and is thus more specific for myocardial necrosis. Cardiac troponin I and T are sensitive and specific markers of damage to the heart.
49
What is the timing of biomarker release after myocardial injury?
CK levels rise within 4–8 hours, peak at 12–24 hours, and return to baseline by 4 days. The CK-MB isoenzyme curve peaks slightly earlier and is cleared within 48 hours. Troponin I and T may be detected as early as 2 hours after MI but usually rise by 6 hours, peak at 12 hours, and return to baseline by 7–10 days, making the test useful to identify patients with delayed presentations of MI.
50
What is the most likely diagnosis?
Left heart failure (LHF) is evidenced by orthopnea, paroxysmal nocturnal dyspnea, dyspnea on exertion, and mild edema.
51
What are the common causes of Left heart failure (LHF) ?
Hypertension, myocardial infarction, valvular heart disease, myocarditis, and cardiomyopathies are associated with the development of LHF.
52
What symptoms help differentiate right heart failure from left heart failure?
Right heart failure is characterized by compromised venous return. This can manifest as ascites, significant edema of the lower extremities, jugular venous distention, and hepatosplenomegaly secondary to liver and spleen congestion.
53
This patient is at risk for which other conditions?
LHF is the most common cause of right heart failure. In addition, her history of smoking increases her risk for chronic lung disease. This can lead to cor pulmonale, characterized by right ventricular hypertrophy and failure due to pulmonary congestion in patients with lung disease or pulmonary hypertension. Emphysema is commonly associated with cor pulmonale.
54
What are the likely findings on gross pathology?
Hemosiderin-laden macrophages in the lung are commonly seen in LHF. If LHF leads to right heart failure, patients may develop chronic passive liver venous congestion (called nutmeg liver). Congestion in the central region of the hepatic lobule causes deposition of red/brown pigment from blood cells and can lead to centrilobular necrosis.
55
What is the most likely diagnosis?
Deep venous thrombosis (DVT) is most common in the lower extremities. Hospitalized patients are at high risk for DVT and the associated complications of pulmonary embolism. Risk of DVT is higher in surgical patients than medical patients and is particularly high for patients who have had hip or knee surgery.
56
How is VTE diagnosed?
The level of D-dimer, a fibrin degradation product, is often elevated in DVT. Assays for D-dimer are highly sensitive and have a low false-negative rate in symptomatic patients. A negative D-dimer test therefore may exclude DVT in low-risk patients. In DVT-prevalent populations (eg, surgical patients), additional tests may be used to diagnose or confirm DVT, especially deep venous ultrasonogram with examination for the flow abnormalities (that would be present with a thrombus). Other tests include MRI and venography.
57
In what conditions other than DVT is D-dimer elevated?
D-dimer may be elevated in a number of inflammatory conditions including liver disease, autoimmune disease, malignancy, surgery, and in elderly patients. D-dimer therefore has a low specificity for DVT.
58
What are the risk factors for DVT?
Risk factors of DVT are described by the Virchow triad. Stasis may increase secondary to surgery, immobility, paresis, increasing age, heart failure, pregnancy, or obesity. Vessel injury may result from smoking, prior DVT, catheterization, or varicose veins. Numerous hereditary conditions result in hypercoagulability. Other hypercoagulable states include malignancy, estrogen therapy, acute medical illnesses, inflammatory bowel disease, and nephrotic syndrome.
59
What conditions should be included in the differential diagnosis of DVT?
Numerous conditions can mimic DVT, including the following: muscle strain or tear, lymphedema, venous valvular insufficiency, popliteal cysts, and cellulitis.
60
What is the anatomy of the major deep veins in the lower extremities?
The anterior tibial, posterior tibial, and peroneal veins converge at the lower popliteal fossa to form a single popliteal vein. The popliteal vein continues medially to become the superficial femoral vein. The deep femoral vein runs laterally and joins the superficial femoral and great saphenous vein in the femoral canal to form the common femoral vein. Thrombus formation in the superficial veins of the legs (thrombophlebitis) has a low risk of thromboembolization or pulmonary embolism formation and thus is not routinely treated with anticoagulation.
61
What is the most likely diagnosis?
Dilated cardiomyopathy (DCM) is defined as a left ventricular (LV) EF < 40% and a ventricular chamber with increased diastolic and systolic volumes. In this patient, it is likely of ischemic etiology. DCM is a major cause of congestive heart failure in young people. Males and African Americans are at an increased risk for DCM.
62
What are causes of Dilated cardiomyopathy (DCM)?
here are many causes of DCM, but they can be broadly categorized as primary or secondary. Primary causes of DCM include idiopathic or genetic factors. Secondary causes of DCM include ischemia, hypertension, valvular disease, drugs (alcohol, cocaine, doxorubicin), infectious disease (Chagas disease, coxsackievirus), vitamin B deficiency, and postpartum state.
63
What typical signs and symptoms are associated with Dilated cardiomyopathy?
DCM results in depressed systolic pump function and the typical symptoms of myocardial failure, as seen in this patient. Enlargement of the ventricle dilates the annulus and displaces the papillary muscles. This can result in the holosystolic murmur of mitral regurgitation. The subsequent increase in early diastolic atrium-to-ventricle flow results in the diastolic rumble. Prior MIs are characterized by deep, broad Q waves. The presence of Q waves in the precordial leads suggests an old anterior MI.
64
What is the pathogenesis of Dilated cardiomyopathy (DCM)?
After an MI, it is hypothesized that the reduced peripheral (particularly renal) perfusion leads to fluid retention in an attempt to increase cardiac output. This ultimately results in cardiac remodeling. Figure 5-10 shows the relationship between renin- angiotensin and autonomic nervous system activation and cardiac myocyte cell death.
65
What is cardiac remodeling?
Following MI, necrotic muscle cells are replaced by proliferating fibroblasts and collagen deposition. The development of scar tissue in the myocardium thins the ventricle walls, reshapes the ventricle, and ultimately adversely affects cardiac function.
66
What is the appropriate treatment for Dilated cardiomyopathy (DCM)?
Angiotensin-converting enzyme inhibitors and β-blockers are appropriate in symptomatic patients, because they slow the remodelling process and reduce myocardial workload, respectively. In so doing, they improve cardiac output and reduce mortality. Diuretics may be used in volume-overloaded patients. In some cases, anticoagulation may be required, as there is a predilection for thrombi to form in a dilated cardiac chamber. Digitalis may also improve the EF, but survival benefit is uncertain. Aldosterone antagonists have been shown to provide a mortality benefit in patients with severe heart failure symptoms.
67
What is the most likely diagnosis?
Acute endocarditis caused by Staphylococcus aureus. The man’s new heart murmur suggests a possible valvular lesion as the source of infection. In this case, a Gram stain that demonstrates gram-positive organisms in clusters suggests staphylococci.
68
Which valvular structure is most commonly affected in Acute endocarditis?
In the general population, endocarditis most frequently involves the mitral valve. Common organisms include staphylococcal and streptococcal species. In intravenous (IV) drug users, however, the tricuspid valve is most commonly involved. In these cases, venous blood contaminated by nonsterile venipuncture crosses the tricuspid valve first.
69
What other microorganisms are associated with acute endocarditis?
Acute endocarditis develops in previously normal valves; S aureus, Neisseria gonorrhoeae, and Streptococcus pneumoniae are common culprits. Subacute endocarditis is diagnosed in previously abnormal or damaged valves and is often secondary to previous rheumatic fever. Viridans streptococci, Staphylococcus epidermidis, enterococci, and Candida are common causes of subacute endocarditis.
70
What is acute endocarditis called when it occurs with systemic lupus erythematosus?
Libman-Sacks endocarditis, or “sterile endocarditis,” occurs with systemic lupus erythematosus. This condition is believed to result from autoimmune damage to cardiac valves.
71
What characteristic of the Staphylococcus aureus microbe confers resistance antibiotics?
Penicillin resistance by S aureus develops through the secretion of penicillinase (a β-lactamase), which inactivates penicillin. Vancomycin resistance develops through the acquisition of a gene that changes the vancomycin binding site from a D-ala D-ala sequence to D-ala D-lac on bacterial cell wall precursors. Loss of the binding site results in resistance to vancomycin.
72
What are the complications of Acute endocarditis caused by Staphylococcus aureus?
A serious complication of endocarditis is embolization of valvular vegetations. Embolization to the brain, liver, kidneys, and bone may lead to abscess and may have profound neurological and physiological effects. Small pieces of vegetations may embolize peripherally leading to Roth spots (retinal hemorrhages), Janeway lesions (nontender hemorrhagic lesions on palms or soles), and Osler nodes (tender lesions on palms or soles).
73
What is the most appropriate treatment for acute endocarditis?
The best treatment for infective endocarditis is IV antibiotics targeted at the causative agent.
74
What is the most likely diagnosis?
Hypertrophic cardiomyopathy (HCM) is suggested by the patient’s age, symptoms, family history of sudden death (a common presentation in young people with HCM), murmur, and ECG findings. It is characterized by the overgrowth of myocardium with myocardial disarray.
75
What is the epidemiology of Hypertrophic cardiomyopathy?
HCM is believed to be the most common genetic cardiovascular disorder. Its overall prevalence is estimated to be 1:500 to 1:1000. No gender preference is observed, and clinical manifestation varies by age.
76
How should the ECG findings in Figure 5-11 be interpreted?
77
What is the classic murmur associated with Hypertrophic cardiomyopathy?
78
What major classes of pharmacologic agents may benefit a patient with Hypertrophic cardiomyopathy?
β-Adrenergic antagonists are used to decrease heart rate, myocardial oxygen consumption, and outflow tract gradient and to increase diastolic filling time.
Calcium channel blockers are used to decrease inotropy and chronotropy and improve diastolic relaxation. Verapamil is preferred because it acts primarily on the heart rather than the blood vessels and so has minimal effects on the afterload.
79
What additional symptoms would indicate an emergent situation?
Blood pressure goals in most patients are < 140/90 mm Hg; the goal is lower in patients with diabetes or other comorbid conditions. Hypertensive urgency is characterized by severely elevated blood pressure (systolic > 180 mm Hg or diastolic > 110 mm Hg) without evidence of end-organ damage. Hypertensive emergencies are characterized by severely elevated blood pressure with signs of end-organ damage including mental status changes, stroke, myocardial infarction, and renal failure.
80
What is the primary treatment for this condition?
Lifestyle modification is attempted before pharmacologic therapy is undertaken. This includes moderate dietary sodium restriction, weight reduction in obese patients, avoidance of smoking and excess alcohol intake, increased fruit and vegetable intake, and regular aerobic exercise.
81
What is the initial pharmacologic therapy of choice for hypertension?
The initial pharmacologic therapy of choice is a thiazide diuretic, which inhibits sodium chloride reabsorption in the distal tubule, thereby promoting diuresis. Compared to other classes of diuretics, these drugs are equally effective and less expensive. Chlorthalidone has the longest half-life and the best evidence to support its use. Hydrochlorothiazide is also frequently used.
82
What are the mechanism of action and major toxicities of angiotensin-converting enzyme (ACE) inhibitors?
ACE inhibitors, such as captopril and enalapril, are particularly useful when comorbidities such as diabetes mellitus with microalbuminuria and left heart failure coexist with hypertension. These drugs work by inhibiting ACE, thereby reducing levels of angiotensin II and preventing inactivation of bradykinin (a vasodilator). Toxicities include cough, angioedema, taste changes, hypotension, fetal renal damage, rash, and hyperkalemia. Angiotensin II receptor blockers such as losartan have a decreased incidence of cough as an adverse effect.
83
What are the mechanisms of action and major toxicities of β1-adrenergic blockers?
β1-Selective blockers (acebutolol, betaxolol, esmolol, atenolol, and metoprolol) are particularly useful
in decreasing mortality after ischemic events and in patients with congestive heart failure. They work by blocking β-adrenergic receptors, slowing the heart rate, and decreasing blood pressure. Although β1-specific antagonists have fewer respiratory adverse effects than nonspecific β-blockers (such as propranolol), major adverse effects include bradycardia, congestive heart failure, atrioventricular block, sedation, sleep alteration, and impotence.
84
What are the mechanisms of action and major toxicities of calcium channel blockers?
Calcium channel blockers such as nifedipine (which is more specific for vasculature than verapamil and diltiazem) block voltage-dependent L-type calcium channels of smooth and cardiac muscle, thereby reducing muscle contractility. They are particularly useful when hypertension is not adequately controlled with the above agents. Major toxicities include cardiac depression, peripheral edema, flushing, dizziness, and constipation.
85
What is the most likely diagnosis?
Kawasaki disease (mucocutaneous lymph node syndrome). Commonly presents with fever lasting > 5 days, erythematous rash (Figure 5-12), edema in the conjunctivae, lips, and mouth (“strawberry tongue”), palmar and solar erythema, cervical lymphadenitis, and mucositis.
86
What is the pathophysiology of Kawasaki disease?
This acute autoimmune disorder is characterized by necrotizing, systemic vasculitis of small and medium- sized vessels as well as veins. Although the exact cause is unknown, it is believed to be triggered by infection evidenced by the fact that Kawasaki disease usually does not occur prior to the age of 6 months, a period of life in which maternal antibodies still circulate in the infant.
87
Which patients are most commonly affected by Kawasaki disease?
Kawasaki disease is most common in children 6 months to 5 years old. Individuals of Asian ancestry are more often affected.
88
What is the most appropriate treatment for Kawasaki disease?
High-dose aspirin and intravenous immunoglobulin G are the preferred treatment. Steroids are used only after failure of first-line treatment. Patients should be treated as promptly as possible to prevent acute complications, including coronary aneurysm, myocardial infarction, severe heart failure, and hydrops of the gallbladder.
89
Which other infectious diseases commonly present as palmar and solar erythema?
Syphilis, Rocky Mountain spotted fever, meningococcemia, and coxsackievirus A infection can also present as palmar and solar erythema.
90
What is the most likely diagnosis?
Mitral valve prolapse (MVP), a condition found in 0.6%–2.4% of the population, is the most common valvular heart disease. Most cases are asymptomatic and discovered incidentally. However, left atrial enlargement may occur, resulting in occasional benign supraventricular arrhythmia that the patient perceives as palpitations. Men and women are affected equally. MVP is defined by the echocardiographic measurement of the superior displacement of one or both mitral leaflets into the left atrium (LA).
91
What is the pathogenesis of Mitral Valve prolapse?
MVP is multifactorial in origin with an autosomal dominant pattern of inheritance in some families. It can occur as a result of changes within the valvular tissue, geometric disparities between the left ventricle and mitral valve, and connective tissue disorders, such as Marfan syndrome (prevalence of 91%) and Ehlers- Danlos syndrome (6%).
92
How does standing and squatting affect the timing of the systolic click in MVP?
In MVP, the systolic click represents the sudden tensing of the mitral valve apparatus as the leaflets prolapse into the left atrium during systole and occurs when the left ventricle reaches a critical volume (CV) during ventricular contraction. Standing decreases the end-diastolic volume (EDV) by reducing systemic afterload and venous return, thereby allowing the CV to be reached earlier. The click therefore is heard closer to S1. In contrast, squatting increases the EDV. The click is thus heard closer to S2.
93
What are the major complications of Mitral Valve Prolapse (MVP)?
MVP typically has a benign prognosis. A poorer prognosis is more likely in male, elderly patients with a systolic murmur, thickened and redundant mitral leaflets, or left atrial or ventricular hypertrophy. The most common complication is infective endocarditis as the mitral valve is partially damaged and therefore at increased risk for bacterial colonization. Other complications of MVP include severe mitral valve regurgitation, and cerebrovascular ischemic events. Risk stratification by clinical examination and echocardiography is necessary.
94
What is the most likely diagnosis?
Chest pain that occurs at rest is commonly seen in unstable angina, subendocardial infarction, and transmural infarction. However, only unstable angina presents without damage to the myocardium, and hence does not produce a troponin leak. In this condition, the flow of a coronary vessel is limited to the extent that it cannot meet the metabolic demand of the heart, but it does not cause death of myocardial tissue. Rest and dilation of the coronary vessels (nitroglycerin) improve the pain. Given his history of coronary heart disease, unstable angina is most likely.
95
What is the mechanism of action of nitroglycerin?
Nitrates undergo denitration that results in the liberation of nitric oxide (NO) in vivo. NO activates guanylyl cyclase, thereby increasing cyclic guanosine monophosphate (cGMP) concentrations and stimulating cGMP-dependent protein kinases. In smooth muscles this results in the dephosphorylation of myosin light chains and inhibition of calcium entry and increases potassium channel activity. This ultimately leads to vasorelaxation. Clinically, this leads to a reduction in preload (venous relaxation) and a reduction in afterload (some arterial relaxation). As the heart operates at lower pressures, myocardial oxygen demand is also reduced. Furthermore, nitroglycerin dilates coronary vessels, improving myocardial oxygenation. If combined with a phosphodiesterase inhibitor such as sildenafil, life-threatening hypotension may result.
96
How can ECG studies differentiate between ischemia, subendocardial infarction, and transmural infarction?
Inverted T waves and pathologic Q waves occur once the infarction progresses (Figure 5-13A). In the event of a subendocardial infarction, the subtotal occlusion of the feeding artery allows the epicardial side of the myocardium to remain viable while the endocardial side is starved of nutrients. Subendocardial infarctions appear as inverted T waves without ST-segment changes on ECG. Stable and unstable angina pectoris lead to ST-segment depression in at least two contiguous leads (Figure 5-13B). Transmural infarction features ST-segment elevation > 1 mm in at least two contiguous leads.
97
What is the most likely diagnosis?
Acute myocardial infarction (AMI) most often results from a thrombotic event in a coronary artery due to plaque rupture. Myocardial tissue dies (infarction) if perfusion is not reestablished.
98
How does diabetes affect the presentation of myocardial infarction?
Typical myocardial infarctions feature crushing chest pain that may radiate to the arms, back, or jaw. However, since patients with diabetes are prone to develop neuropathies, pain signals from the heart may not be relayed to the brain effectively, resulting in myocardial infarctions without chest pain or atypical pain patterns. A special instance in all patients regardless of diabetes is the inferior MI, caused by an occlusion of the right coronary artery. It commonly presents with abdominal discomfort but no chest pain.
99
What serum markers are useful in making a diagnosis of Acute myocardial infarction?
Serum cardiac markers such as creatinine kinase-MB fraction (CK-MB) and cardiac-specific troponin I (cTnI and cTnT), are released into the blood at varying times in response to cardiac tissue necrosis after AMI. cTnI, which is more specific than the other markers for AMI, is used within the first 4 hours, and cTn1 levels may remain elevated for 7–10 days. CK-MB levels peak about 20 hours after the onset of coronary artery occlusion and usually return to baseline within 48 hours.
100
What complications are associated with an acute MI?
101
What is the most likely diagnosis?
Pericarditis often presents with diffuse ST-segment elevation, positional chest pain, and friction rub. The latter is due to inflammation of the pericardium, resulting in decreased production of lubrication. The typical friction rub has three phases (atrial contraction, ventricular contraction, and ventricular relaxation).
102
What is an ECG likely to show in pericarditis?
Classic findings of pericarditis include diffuse ST-segment elevations and PR-segment depression (Figure 5-14). This is in contrast to the ST-segment elevations in some MIs, in which the elevations are limited to ischemic regions (contiguous leads). Likewise, the J point (where the QRS-complex transitions into the ST segment) is usually a smooth curve in pericarditis but abrupt in transmural infarction, allowing distinction when multivessel infarction is suspected.
103
How is pericarditis classified?
There are three types of pericarditis: serous, fibrinous and hemorrhagic. Risk factors for the development of serous pericarditis include systemic lupus erythematosus, rheumatoid arthritis, and uremia. Preceding viral infection is also possible cause of serous pericarditis, as is the case in this patient. Risk factors for fibrinous pericarditis include uremia, myocardial infarction (Dressler syndrome), and rheumatic fever. Risk factors for hemorrhagic pericarditis include tuberculosis and malignancy.
104
Which physical examination and ECG findings would be suspicious for cardiac tamponade in a patient with pericarditis?
Tamponade is the compression of the heart by fluid in the pericardium, which inhibits diastolic filling, reducing the amount of blood available for the heart to pump (reduced cardiac output). This results in systemic hypotension and elevated jugular venous pressure. The fluid around the heart also causes distant, or muffled, heart sounds. Pulsus paradoxus, a decrease in arterial blood pressure by > 10 mm Hg during inspiration, is also a sign of tamponade. Electrical alternans, a beat-to-beat variation in the amplitude of the QRS complex, may also be noted.
105
What is the most likely diagnosis?
The patient’s severe gastrointestinal symptoms that are out of proportion to the physical signs elicited suggest mesenteric ischemia. Given the sudden onset, this is most likely a thrombotic event. Ischemia affecting the small bowel initially presents with severe pain; peritoneal signs develop later. Ischemia of the large bowel is less painful and typically presents with hematochezia.
106
What composes the arterial supply of the intestines?
The superior mesenteric artery (SMA) supplies part of the duodenum and part of the head of the pancreas (the territory of inferior pancreaticoduodenal artery), jejunum, ileum, ascending colon, and proximal two-thirds of the transverse colon. The inferior mesenteric artery (IMA) supplies the hindgut, which includes the distal third of the transverse colon, the descending colon, the sigmoid colon, and the rectum. This is schematically shown in Figure 5-15.
107
What is the most appropriate treatment for a patient with mesenteric ischaemia?
Blood flow must be restored urgently. Thrombolytic medications may resolve the thrombus but also predispose the patient to severe gastrointestinal bleeding upon reperfusion. Hence, a surgical approach is favored (thrombectomy, bypass). In addition, any necrotic segments of the intestine must be surgically removed.
108
What is the most likely diagnosis?
Patent ductus arteriosus (PDA) is indicated by the characteristic continuous “machine-like” murmur and physical examination.
109
What is the purpose of the ductus arteriosus?
The ductus arteriosus (DA) typically originates from the origin of the left pulmonary artery to connect to the lower aspect of the aortic arch at the origin of the left subclavian artery. Before birth, it shunts blood away from the pulmonary vasculature (right-to-left shunt), because the lungs are fluid filled and do not provide oxygenation. Patency is maintained during fetal life by the low arterial oxygen tension and circulating prostaglandins produced largely by the placenta. Upon birth, blood pressure in the pulmonary circulation drops because of the lower resistance in the pulmonary vessels, reversing the blood flow through the DA.
110
What is the pathogenesis of this condition?
The DA typically closes within 2–3 days of birth and becomes the ligamentum arteriosum. This spontaneous closure occurs from a combination of factors, including the increased partial pressure of oxygen secondary to lung-mediated oxygenation, the removal of the vasodilatory effects of prostaglandin E2 (PGE2) derived from the placenta, and a decreased number of PGE2 receptors. Inadequate closure of the DA results in a PDA and permits a left-to-right blood shunt that increases volume load of the left ventricle and the pulmonary arteries.
111
What is the prognosis of a patent ductus arteriosus?
The additional stress on the heart and lungs derived from the left-to-right shunt eventually results in left ventricular hypertrophy and ultimately heart failure, vascular damage, and pulmonary hypertension. Regardless of size, a PDA also increases the risk for infective endocarditis. Pharmaceutical closure can often be achieved with a prostaglandin inhibitor, such as indomethacin. Otherwise, a surgical or catheter-based closure may be required.
112
What is the most likely diagnosis?
This patient has polyarteritis nodosa with palpable purpura and other common symptoms such as weight loss, inflammatory markers, and evidence of vasculitis in her retina.
113
What is the pathophysiology of Polyarteritis nodosa?
Polyarteritis nodosa is an autoimmune disorder characterized by segmental, transmural inflammation of small and medium-sized arteries due to necrotizing immune complexes. Vessels supplying the kidneys, heart, liver, and gastrointestinal tract are most often involved.
114
What laboratory test can help establish the diagnosis of Polyarteritis nodosa?
The presence of perinuclear antineutrophilic cytoplasmic antibody (P-ANCA) correlates with disease activity. P-ANCAs are more commonly seen in small-artery disease. Furthermore, antibody testing against hepatitis B may strengthen the diagnosis, as approximately 30% of cases of polyarteritis nodosa are associated with this infection.
115
What other small to medium vasculitides could this patient have?
Churg-Strauss syndrome is a variant of polyarteritis nodosa characterized by eosinophilia and asthma. Autoantibodies mostly target blood vessels in the lungs, but in the late stage other organ systems can become involved (including the skin). Wegener granulomatosis features ANCAs that damage blood vessels in the upper respiratory tract and kidney. However, it can also involve joints, skin, and the gastrointestinal tract.
116
What complications may be seen in polyarteritis nodosa?
Inflammation of the small and medium-sized arteries induces a local state of hypercoagulability. This may lead to thromboses and subsequent ischemia or infarction of distal tissues. Unfortunate individuals have suffered strokes and heart attacks, but ischemia is possible in any organ system. Damaged arteries are at risk for aneurysms. Treatment with prednisone and cyclophosphamide, however, produces remission or even cure in approximately 85% of affected individuals and prevents these complications.
117
What is the most likely diagnosis?
This patient has rheumatic heart disease. Mitral stenosis (fish-mouth buttonhole deformity) is often seen in patients with previous rheumatic fever infection. This disease primarily affects the mitral and aortic valves; involvement of tricuspid and pulmonary valves is rare. This condition is not commonly seen in the United States.
118
What hemodynamic changes occur in the heart in rheumatic heart disease?
Left atrial diastolic pressure increases in cases of mitral stenosis because the left atrium must pump against a small, stiff valve. This can increase pulmonary hydrostatic pressure, leading to pulmonary congestions and edema. Eventually, right heart failure ensues.
119
What pathogen is responsible for the underlying infection in Rheumatic heart disease?
Rheumatic heart disease is a result of group A β-hemolytic streptococci infection. Valvular heart disease, as in this patient, often occurs many years after the acute infection. Antistreptolysin O antibodies are often seen in patients long after the acute infection resolves.
120
What is the appropriate treatment for Rheumatic heart disease?
Cautious use of diuretics and sodium restriction to relieve pulmonary congestion is recommended. Surgery for valve replacement may be indicated for patients with severe symptoms. Prophylactic antibiotics for endocarditis are indicated for all invasive procedures, including dental work.
121
What is the most likely diagnosis?
Biopsy of the temporal artery reveals temporal arteritis. An elevated erythrocyte sedimentation rate and elevated C-reactive protein levels are nonspecific markers associated with temporal arteritis.
122
Which histopathologic features are associated with Temporal arteritis?
Temporal arteritis is a systemic vasculitis of large and medium-sized vessels. It is not restricted to the temporal artery. Mononuclear infiltrates in vessel walls and frequent giant cell formations are expected findings (Figure 5-16).
123
What is the appropriate treatment for Temporal arteritis?
Corticosteroids should be started as soon as possible. Nonsteroidal anti-inflammatory drugs can be given for pain.
124
What complications are associated with Temporal arteritis?
Without treatment, blindness in one or both eyes due to involvement of the ophthalmic artery or posterior ciliary arteries is the most common complication. Patients may also have fever, fatigue, new-onset headache, and jaw or arm claudication. More serious complications, such as thoracic aneurysm, occur less frequently. Additionally, temporal arteritis is often associated with polymyalgia rheumatica, a syndrome that features pain and stiffness in muscles and joints of the hips, shoulders, and neck. It is thought to have an autoimmune etiology.
125
What is the most likely diagnosis?
Tetralogy of Fallot (TOF) (cyanotic congenital heart disease known as “blue baby syndrome”) presents as dyspnea on exertion, such as feeding or crying. Exertion results in systemic vasodilation, which lowers left-sided resistance, thereby increasing the right-to-left shunting of blood. Bypass of oxygen exchange in the lungs causes hypoxia and cyanosis. Squatting significantly increases systemic (left-sided) resistance, reducing the amount of blood shunted and alleviates symptoms.
126
What anatomic findings are characteristic of Tetralogy of Fallot?
Anatomic findings in TOF are as follows: Pulmonary stenosis (1); Right ventricular hypertrophy (2); Overriding aorta (deviation of the origin of the aorta to the right) (3); and Ventricular septal defect (VSD; 4); (mnemonic: PROVe).
127
Which developmental defect is responsible forTetralogy of Fallot?
In TOF, the infundibular septum (the portion of the septum adjacent to the outflow tracts) is anteriorly and superiorly displaced during development, leaving a hole in the ventricular septum (Figure 5-17). This displacement also causes pulmonary stenosis by blocking flow to the pulmonary artery; the result is increased pressure on the right side of the heart and right ventricular hypertrophy.
128
What is the characteristic radiologic finding in Tetralogy of Fallot?
X-ray of the chest typically shows a boot-shaped heart, due to right ventricular hypertrophy and the absence of a pulmonary artery shadow above the left side of the heart. An echocardiogram with Doppler mode shows the altered pattern of blood flow.
129
What additional physical finding is commonly associated with Tetralogy of Fallot?
Clubbing of the fingers may appear in adults (Figure 5-18) secondary to chronic hypoxemia. It is believed that the lungs secrete growth factors in patients with chronic hypoxia, resulting in abnormal tissue growth that first becomes evident in the distal phalanges.
130
What is the most likely diagnosis for this condition?
Truncus arteriosus (TA) accounts for 1% of congenital cardiac malformations. It is also associated with DiGeorge syndrome, as is the case in this patient.
131
What is the characteristic anatomy in Truncus arteriosus (TA)?
The TA is the embryologic precursor that normally separates into the aorta and pulmonary artery by formation of the spiral septum. Persistent TA is caused by failure of the spiral septum to develop and thereby failure of aorta and pulmonary artery to septate. Normally, neural crest cells that are present in the TA grow in a spiral formation, separating the two outflow tracts and forming the intertwined aorta and pulmonary artery. If this septum fails to form, a single outflow tract persists (Figure 5-19A). A ventricular septal defect (VSD) is always present; lack of a VSD in the setting of TA is incompatible with life and results in stillbirth. Instead of separate aortic and pulmonary valves, there is one truncal valve with two to six leaflets (leading to the characteristic absence of S2 splitting). Surgical repair of these defects is required for survival (Figure 5-19B).
132
What are the reasons for this patient’s symptoms?
The clinical presentation depends on the amount of pulmonary flow. High pulmonary flow ultimately increases arterial oxygen saturation, reducing risk of cyanosis. However, this patient likely has low pulmonary flow; this results in central cyanosis and earlier presentation with congestive heart failure, which is indicated by the tachycardia and respiratory distress.
133
What is the most likely diagnosis?
Wolff-Parkinson-White (WPW) syndrome (also known as preexcitation syndrome).
134
What is the pathophysiology of Wolff-Parkinson-White (WPW) syndrome?
In a normal heart, the only excitatory pathway between the atria and ventricles is the atrioventricular (AV) node. In WPW, the presence of an abnormal band of myocytes creates an accessory conduction pathway, distinct from the AV node, between the atrial and ventricular systems Because the myocytes contain sodium channels, whereas the AV node has calcium channels, excitation often progresses faster through the accessory pathway than the AV node.
135
Why is the PR interval on ECG shortened in Wolff-Parkinson-White (WPW) syndrome?
The PR interval is the interval between atrial excitation (the P wave) and ventricular excitation (the QRS complex). Thus, it is analogous to the conduction time through the AV node. It is shortened in WPW syndrome because AV conduction occurs via a faster, accessory pathway (frequently, the bundle of Kent), which bypasses the AV node.
136
What would be the consequence if a patient with Wolff-Parkinson-White (WPW) syndrome developed atrial fibrillation?
The consequences would be potentially lethal. Atrial fibrillation has an atrial rate of up to 300 excitations/ min. In a normal heart, the AV node is still refractory when subsequent depolarizations arrive and maximally allows a ventricular rate of approximately 150 depolarizations/min. However, the accessory pathway has a short refractory period and may transmit excitatory impulses at their atrial rate. Ventricular contraction at up to 300/min does not allow enough time for ventricular filling and sudden cardiac death occurs.
137
Why are class II and class IV antiarrhythmic drugs not useful in Wolff-Parkinson-White (WPW) syndrome?
Class II and IV antiarrhythmic agents, the β-blockers and calcium channel blockers, may not be useful in patients with WPW syndrome because they increase AV node refractoriness and decrease AV node conduction velocity. They do not slow conduction over accessory pathways, and may even shorten the refractory period for accessory pathways. This may increase ventricular response to atrial fibrillation or flutter, causing hemodynamic collapse. Instead, quinidine, disopyramide, and procainamide may be used to control arrhythmias in this syndrome.
138
What is the appropriate treatment for Wolff-Parkinson-White (WPW) syndrome?
For most patients with WPW syndrome, electrophysiologic ablation is performed to ablate the accessory pathway. Cure is achieved in 90% of cases with no need for medication.
139
What is the most likely diagnosis?
Wegener granulomatosis. Necrotizing granulomatous vasculitis of small and medium-sized vessels leads to manifestations in the kidney and lungs (Figure 5-21).
140
What laboratory test can help establish a diagnosis of Wegener granulomatosis?
The presence of C-ANCA is associated with Wegener granulomatosis, which must be differentiated from Goodpasture syndrome, an autoimmune disorder that also presents with hemoptysis and renal disease (Table 5-2). Instead of C-ANCA antibodies, Goodpasture syndrome features anti–glomerular basement membrane antibodies (anti-GBM).
141
What are the likely findings on gross pathology of the kidney in Wegener granulomatosis?
Renal involvement in Wegener granulomatosis commonly manifests as a pauci-immune or type III rapidly progressive glomerulonephritis. Immunofluorescence reveals no antibodies or immune complex deposition. By contrast, Goodpasture syndrome shows linear deposition of anti-GBM antibodies.
142
If a patient with Wegener granulomatosis also had severe renal dysfunction, which treatment should be avoided?
Methotrexate, although therapeutic, can be nephrotoxic in patients with Wegener granulomatosis. Preferred treatments include other immunosuppressants such as cyclophosphamide and corticosteroids.
143
What other findings are common in patients with Wegener granulomatosis?
Perforation of the nasal septum (the so-called “saddle-nose” deformity; Figure 5-22), chronic sinusitis, mastoiditis, cough, hemoptysis, hematuria, and RBC casts are common findings in patients with Wegener granulomatosis. See Table 5-2 for the distinguishing features of Wegener granulomatosis and Goodpasture syndrome.
