Cardiology



Cardiology


Simon Shakar

Ronald Zolty

Joann Lindenfeld



Acute Pericarditis and Cardiac Tamponade



  • What are the most common causes of acute pericarditis?


  • What is cardiac tamponade?


  • Does acute pericarditis often result in cardiac tamponade?


  • What are the signs and symptoms of pericarditis and tamponade?


  • How is the echocardiogram helpful in the diagnosis of pericarditis or tamponade?


  • What is the treatment for cardiac tamponade?



Discussion



  • What are the most common causes of acute pericarditis?

    The most common causes of acute pericarditis are idiopathic, viral infection, uremia, myocardial infarction MI), trauma, cardiac surgery, and neoplasm.


  • What is cardiac tamponade?

    Cardiac tamponade results from accumulation of fluid within the pericardium. As fluid accumulates, intrapericardial pressure increases, limiting filling of the heart and reducing stroke volume. As intrapericardial pressure rises, cardiac filling is increasingly limited. Ultimately, pressures equalize in the left atrium, pulmonary vasculature, right atrium, and superior vena cava (SVC); ventricular filling is progressively impaired and circulatory collapse ensues.


  • Does acute pericarditis often result in cardiac tamponade?

    Acute pericarditis results in tamponade only rarely. Tamponade is more common in end-stage renal disease and neoplastic disease despite the frequent absence of an identifiable episode of acute pericarditis in these conditions.


  • What are the signs and symptoms of pericarditis and tamponade?

    The most common symptom of acute pericarditis is chest pain. The pain is generally sharp and is worse with cough, deep inspiration, and recumbency. A pericardial friction rub is the most common finding in acute pericarditis. It often has three components that occur in systole, and early and late diastole when the heart is moving and the pericardial surfaces rub against one another. Symptoms of tamponade depend on the degree of hemodynamic compromise. The common symptoms of pericardial effusion with tamponade include dyspnea (80%), cough (30%), orthopnea (25%), and chest pain (20%). The common signs of pericardial effusion with tamponade are jugular venous distension and tachycardia (both nearly 100%), pulsus paradoxus (89%), systolic blood pressure ≤90 mm Hg (52%), and pericardial rub (22%).


  • How is the echocardiogram helpful in the diagnosis of pericarditis or tamponade?

    The echocardiogram is the most accurate and easily available tool to detect and quantify pericardial fluid. However, it is often not of diagnostic value in acute pericarditis because the absence of pericardial fluid does not exclude the diagnosis of acute pericarditis, especially in idiopathic or viral pericarditis. In patients with pericarditis due to neoplasm, bacterial infection, trauma, or cardiac surgery, the echocardiogram may provide helpful information about the etiology of the effusion. For example, metastases may be visible on the pericardial surfaces.

    The echocardiogram is the most commonly used technique for the diagnosis of cardiac tamponade. Typical findings in addition to the presence of pericardial fluid include right atrial and right ventricular diastolic collapse, exaggerated respiratory changes in tricuspid and mitral valve flow, and plethora of the inferior vena cava. Because the limitation of cardiac filling is progressive as the effusion increases, findings of tamponade may be detected by
    echocardiogram before the classically described clinical triad of hypotension, paradoxical pulse, and increased systemic venous pressure.


  • What is the treatment for cardiac tamponade?

    Cardiac tamponade requires immediate treatment to relieve the increased end-diastolic pressure and inadequate ventricular filling. The treatment of cardiac tamponade consists of withdrawal of fluid from the pericardial space, generally through a needle inserted percutaneously—a procedure called pericardiocentesis. Pericardiocentesis may be performed using echocardiographic guidance to place a needle or a catheter in the intrapericardial space or in the cardiac catheterization laboratory using fluoroscopic guidance. Intravenous (IV) fluids such as blood or saline may be used, but only as a temporizing measure. Volume administration is useful only in hypovolemic patients. In normovolemic patients, the administration of fluid may exacerbate the intrapericardial pressure.



Case Discussion



  • What is the most likely clinical diagnosis of this patient’s chest pain?

    The most likely clinical diagnosis of this patient’s chest pain is acute idiopathic or viral pericarditis. Relatively common causes of acute chest pain that must be considered are MI or ACS, pericarditis, aortic dissection, pneumonia, pulmonary embolus, costochondritis, and pneumothorax. The pertinent features of the history and physical examination that lead to this diagnosis are that the pain was preceded by a viral prodrome and was very clearly positional and exacerbated by inspiration, which strongly suggests pericardial pain. Pericardial pain does not improve with NTG, but the lack of response to NTG does not exclude an acute MI. The patient’s vital signs were stable except for a slight fever and tachycardia that are also very frequent in either acute pericarditis or MI. The absence of tachypnea, together with the normal examination findings and normal D-dimer, make acute pulmonary embolization unlikely. Acute costochondritis is often positional but associated with exquisite pain on palpation of the involved costochondral junction, and is not associated with ECG changes. If the examination and chest radiographic findings are normal and there is no past history of smoking, forceful coughing, or trauma, the likelihood of acute pneumothorax is low.

    The remaining two diagnoses, acute pericarditis versus MI, can often be differentiated on the basis of the history and physical examination findings, the ECG, and troponin. The sharp quality of the substernal chest pain, which is associated more with the recumbent position, deep breathing, and coughing, and which is improved by sitting up, is atypical for MI but a classic symptom of pericarditis. The ECG was initially more consistent with pericarditis but an acute MI could not be excluded. The absence of significant coronary obstruction strongly argued against an acute MI, a finding confirmed by the normal troponin.


  • On the basis of your clinical impression of this patient’s presentation, what features would be expected on the ECG?

    Sinus tachycardia and ST-segment elevation are often the earliest ECG findings, although the absence of ECG changes does not exclude the diagnosis of pericarditis.
    The typical changes of acute pericarditis often evolve over hours or days and are thought to be caused by a myocardial current of injury due to inflammation. The ECG in acute pericarditis evolves usually through four stages over several days. There is early diffuse ST-segment elevation in stage 1. This differs from the ST-segment elevation of acute MI, which is usually localized (anterior, inferior, or lateral), with the ST segments convex upward. In pericarditis, the ST-segment elevation is concave upward and usually involves all the leads except aVR and V1. Stage 2 is defined by normalization of the ST segments and stage 3 is characterized by the development of diffuse T-wave inversions. In stage 4, the T waves return to their normal configuration. PR segment depression is also common in the early phases of acute pericarditis even in the absence of ST-segment elevation and is strongly suggestive of acute pericarditis. An important exception is in pericarditis following an acute MI, in which typical ECG changes of pericarditis may not be present or may be atypical.


  • Is a normal troponin helpful in excluding an acute MI?

    A normal troponin 8 or more hours after the onset of chest pain generally excludes acute MI but does not exclude ACS. However, a mildly elevated troponin may be present with acute myopericarditis. Myocarditis is an inflammatory disease of the cardiac muscle, which can be caused by a variety of different illnesses, many of which are infectious. Typically, myocarditis is associated with cardiac enzyme elevation that reflects myocardial necrosis. When chest pain occurs in the setting of myocarditis it may be associated with concomitant pericarditis and is called myopericarditis.


  • What is the most effective treatment for acute pericarditis?

    In the treatment of idiopathic or viral pericarditis, the goals of therapy are relief of pain and resolution of inflammation. First-choice therapy is the administration of nonsteroidal antiinflammatory drugs (NSAIDs) or aspirin. The administration of colchicine alone or in combination with NSAIDs might be another therapeutic alternative. The use of corticosteroids is usually reserved for patients with pericarditis secondary to autoimmune disease.


  • What is the most likely cause of the hypotension in this patient?

    The hypotension in this patient is most likely due to the cumulative effects of the medications he has been given (morphine and NTG). The accumulation and potentiation of medications, especially in the elderly, is a common clinical problem in the acute care setting. The combination of morphine and NTG in this patient may have induced sufficient vasodilation to cause hypotension.

    Bleeding is also a possible cause of the hypotension. The administration of IV heparin, aspirin, and platelet glycoprotein IIb-IIIa inhibitor agents may result in gastrointestinal bleeding and melanotic stools. The absence of jugular venous distention and a paradoxical pulse argues against tamponade, but these findings may be absent with vasodilation or volume depletion. A more worrisome possibility is hemorrhagic pericarditis, especially because a new friction rub is heard. If the hypotension does not resolve quickly with discontinuation of NTG and morphine, an echocardiogram is indicated to exclude cardiac tamponade.




Suggested Readings

Imazio M, Bobbio M, Cecchi E, etal. Colchicine in addition to conventional therapy for acute pericarditis: results of the COlchicine for acute PEricarditis (COPE) trial. Circulation 2005;112(13):2012–2016.

LeWinter MM, Kabbani S. Pericardial diseases. In: Braunwald E, ed. Heart disease: a textbook of cardiovascular medicine, 7th ed, Philadelphia: WB Saunders, 2005:1757.

Merce J, Sagrista-Sauleda J, Permanyer-Miralda G, etal. Correlation between clinical and Doppler echocardiographic findings in patients with moderate and large pericardial effusion: implications for the diagnosis of cardiac tamponade. Am Heart J 1999;138:759–764.

Spodick DH. Acute cardiac tamponade. N Engl J Med 2003;349:684–690.

Troughton RW, Asher CR, Klein AL. Pericarditis. Lancet 2004;363:717–727.


Acute Pulmonary Edema



  • What are the two most common underlying mechanisms of pulmonary edema?


  • What are the most common causes of acute cardiogenic pulmonary edema?


  • What is the immediate treatment of acute cardiogenic pulmonary edema?


Discussion



  • What are the two most common underlying mechanisms of pulmonary edema?

    Acute pulmonary edema can have a cardiogenic or noncardiogenic etiology. In cardiogenic pulmonary edema, a high pulmonary capillary pressure is responsible for the transudation of protein-poor fluid into the lungs caused by an imbalance of Starling’s forces. With acute rises in pulmonary capillary pressure, the pulmonary lymphatics cannot rapidly increase the rate of fluid removal; as a result, pulmonary edema occurs.

    Noncardiogenic pulmonary edema is caused by altered alveolar capillary permeability due to acute lung injury. Transudation of fluid into the alveolar space is not dependent on an elevated pulmonary capillary wedge pressure but is exacerbated by an elevated pulmonary capillary pressure. The disorders most frequently resulting in increased permeability pulmonary edema are the acute respiratory distress syndrome (ARDS) and, less commonly, high altitude and neurogenic pulmonary edema.


  • What are the most common causes of acute cardiogenic pulmonary edema?

    The most common causes of acute cardiogenic pulmonary edema are acute ischemia and accelerated hypertension, both causing a sudden increase in left ventricular end-diastolic pressure. Both etiologies result in a stiff left ventricle and decreased diastolic ventricular compliance, impairing ventricular filling during diastole (diastolic dysfunction). Systolic dysfunction may also occur. Other causes of acute cardiogenic pulmonary edema include acute mitral regurgitation such as might result from acute ischemia or a ruptured chordae
    tendinea, or infectious endocarditis, or discontinuation of antihypertensive medications. Acute pulmonary edema may be precipitated by rapid atrial fibrillation or other dysrhythmias. Infection, physical or environmental stresses, changes or noncompliance with medical therapy, dietary indiscretion, or iatrogenic volume overload are less common, but important, causes.


  • What is the immediate treatment of acute cardiogenic pulmonary edema?

    The immediate treatment of acute cardiogenic pulmonary edema should consist of oxygen therapy to maintain an oxygen saturation within the normal range (95% to 98%), noninvasive positive-pressure ventilation if oxygen saturation remains low [i.e., continuous positive airway pressure (CPAP) or bi-level positive airway pressure (BiPAP)], IV diuresis with furosemide or other loop diuretics, IV morphine, and IV vasodilators with NTG, nitroprusside, or angiotensin-converting enzyme (ACE) inhibitors. The patient should be sitting upright unless hypotension is present. If the patient has an ACS, therapy should be dominated by intervention to minimize ischemic injury. If the acute pulmonary edema is associated with shock, IV inotropic drugs such as milrinone or dobutamine may be necessary. If severe hypertension is present, IV nitroprusside or other rapidly acting agents such as labetalol should be given to lower systemic blood pressure. Noninvasive positive-pressure ventilation with CPAP or BiPAP has been shown to reduce the need for invasive mechanical ventilation in patients with acute cardiogenic pulmonary edema and even to reduce mortality compared with standard therapy (oxygen by face mask, diuretics, and nitrates); the same has been shown in a recent meta-analysis study. (see section on Essential Hypertension and Hypertensive Emergencies).




Case Discussion



  • What is causing the pulmonary edema in this patient?

    There are several causes of the pulmonary edema in this patient.



    • MI impairs both the systolic and diastolic function of the left ventricle. A loss of the contractile function of the large anterior wall of the left ventricle (systolic dysfunction) and acute stiffening of the damaged myocardium (diastolic dysfunction) lead to elevated filling pressures of the left ventricle and the left atrium. Elevated pulmonary venous and pulmonary capillary pressures produce an imbalance in the Starling’s forces, resulting in the transudation of fluid into the interstitium and then into the alveolar space.


    • Atrial fibrillation with a rapid ventricular response (170 beats per minute) contributes to the pulmonary edema because (a) the loss of atrial systolic contraction impairs left ventricular filling, which further elevates the left atrial pressure; (b) the rapid ventricular rate results in significant shortening of diastolic filling time further impairing filling of the left ventricle; and (c) the rapid ventricular rate increases myocardial oxygen demands, which may increase ischemia, which in turn worsens the pulmonary edema.


    • Hypertension, especially when chronic and poorly controlled, produces a stiff, hypertrophied myocardium causing elevated ventricular filling pressures. In the setting of acute MI, an increase in blood pressure caused by anxiety, pain, a catecholamine surge, and peripheral vasoconstriction augments the afterload against which the already compromised left ventricle has to work. This leads to a further elevation in ventricular filling pressures, and worsens any ischemia and mitral regurgitation already present.


    • Anxiety secondary to the pain and breathlessness is likely to increase the heart rate and blood pressure, thereby contributing to pulmonary edema by increasing the afterload.


    • A systolic murmur in this setting most likely represents mitral regurgitation secondary to ischemia and papillary muscle dysfunction or, less commonly, rupture of papillary muscle, or an acute ventricular septal defect (VSD). Both acute mitral regurgitation and a VSD result in a systolic murmur at the lower left sternal border. When mitral regurgitation is acute and severe, the systolic murmur may be soft and may not be holosystolic because the left atrial pressure increases rapidly in systole decreasing the mitral regurgitation jet and murmur. The murmur of VSD is generally loud, harsh, and holosystolic due to the vibration of the muscular ventricular septum and a high pressure gradient between the left and right ventricles throughout systole.


  • What medical therapy should be used to treat this patient acutely, and why?

    The most important intervention in this patient is acute reperfusion. An acute coronary angiography will define the coronary anatomy. Percutaneous coronary intervention (PCI) with angioplasty and/or coronary stenting will be indicated if there is no papillary muscle rupture or VSD. Cardiac surgery is necessary if either repair of a VSD or mitral valve replacement for papillary muscle rupture is necessary.
    There are several components to the acute supportive treatment of this patient’s pulmonary edema. The administration of oxygen to maintain arterial oxygen saturation above 90% is important because the alveolar edema interferes with adequate oxygen diffusion. Noninvasive positive-pressure support ventilation is also beneficial and should be used in patients who are still hypoxic despite medical treatment. Morphine (1 to 3 mg at a time in an IV push) diminishes anxiety and decreases central sympathetic outflow, thereby reducing both venous and arterial vasoconstriction, resulting in decreases in ventricular preload and afterload, respectively. Morphine should not be given to patients with diminished sensorium or respiratory drive or hypercapnia because it may precipitate respiratory arrest. Furosemide (20 to 80 mg in a slow IV push) or other loop diuretics cause immediate venodilation, followed by diuresis within approximately 5 to 10 minutes. IV sodium nitroprusside may be used to reduce blood pressure if hypertension is present. NTG, administered as sublingual tablets or by IV drip, relieves the pulmonary edema by producing venodilation and treating acute ischemia. Digoxin may be used to slow the ventricular response to atrial fibrillation. IV diltiazem or a β-blocker may be used to reduce the ventricular response if the patient can tolerate a negative inotropic agent.

    Multiple studies comparing NTG to furosemide or morphine sulfate have demonstrated greater efficacy and safety and a faster onset of action for NTG. Although ACE inhibitors are generally considered the cornerstone for treating chronic heart failure (HF), several very small studies have demonstrated good results for treatment of acute pulmonary edema with this class of agent. Nevertheless, ACE inhibitors should be used with extreme caution in patients with hypotension or significantly impaired renal function.

    It has been demonstrated that systemic infusion of nesiritide has beneficial hemodynamic actions but may cause significant hypotension and no significant benefit in clinical outcomes compared with IV NTG. Also, some concerns have been raised that nesiritide may be associated with an increased risk of death and worsening renal function.



Suggested Readings

Annane D, Bellissant E, Pussard E, etal. Placebo-controlled, randomized, double-blind study of intravenous enalaprilat efficacy and safety in acute cardiogenic pulmonary edema. Circulation 1996;94(6):1316–1324.

Beltrame JF, Zeitz CJ, Unger SA, etal. Nitrate therapy is an alternative to furosemide/morphine therapy in the management of acute cardiogenic pulmonary edema. J Card Fail 1998;4:271–279.

Cotter G, Metzkor E, Kaluski E, etal. Randomized trial of high-dose isosorbide dinitrate plus low-dose furosemide versus high-dose furosemide plus low-dose isosorbide dinitrate in severe pulmonary edema. Lancet 1998;351:389–393.

Pierard LA, Lancelotti P. The role of ischemic mitral regurgitation in the pathogenesis of acute pulmonary edema. N Engl J Med 2004;35:1681–1684.

Sackner-Bernstein JD, Kowalski M, Fox M, etal. Short-term risk of death after treatment with nesiritide for decompensated HF: a pooled analysis of randomized controlled trials. JAMA 2005;293:1900–1905.


Ware LB, Matthay MA. Clinical practice. Acute pulmonary edema. N Engl J Med 2005;353:2788–2796.


Aortic Dissection



  • What is acute aortic dissection?


  • What is the most common cause of aortic dissection in the general population, in men younger than 40 years, and in women younger than 40 years?


  • What is the most sensitive initial diagnostic test for aortic dissection?


  • Where are the most common points of origin for aortic dissections?


Discussion



  • What is acute aortic dissection?

    Acute aortic dissection results from a tear in the aortic intima. Driven by systemic pressure, arterial blood enters the diseased media of the vessel. Within this layer, blood creates a separation plane as it dissects the aorta longitudinally. The area of dissection filled with blood is called the false lumen. The shear forces of the dissecting blood can cause additional intimal tears. As the false lumen fills with blood, it may compress the true lumen, resulting in obstruction of major arteries. Infrequently, dissection can be initiated by hemorrhage into the media without an intimal tear.


  • What is the most common cause of aortic dissection in the general population, in men younger than 40 years, and in women younger than 40 years?

    In the ascending aorta, the most common cause of aortic dissection in the general population is medial degeneration usually associated with aging and hypertension. In the abdominal aorta, atherosclerosis plays a more important role. In men younger than 40 years, the most common cause of dissection is Marfan’s syndrome associated with the more typical cystic medial degeneration lesions. In women younger than 40 years, 50% of all dissections occur during pregnancy.


  • What is the most sensitive initial diagnostic test for aortic dissection?

    The sensitivities of transesophageal echocardiography (TEE), magnetic resonance imaging (MRI), and computed tomography (CT) scan for detection of dissection are similar, with TEE probably having a slight advantage. In most cases, the preferred initial modality is CT scanning because of availability, safety, and convenience. If the patient is not stable, TEE should be considered first as it can be performed in a monitored setting where acute medical therapy can be administered.


  • Where are the most common points of origin for aortic dissections?

    The most common point of origin for ascending aortic dissection is within 2 in. of the aortic valve. For descending aortic dissection, this point is at
    the ligamentum arteriosum, just beyond the takeoff of the left subclavian artery.



Case Discussion



  • What tests would you do first to establish a working diagnosis?

    The first procedure to perform is a careful physical examination. Your examination in this patient confirms the ER findings, but the blood pressure in the left arm is 190/110 mm Hg, and the right arm blood pressure is still 80/40 mm Hg. The discrepancy in pulse and blood pressure between the right and left arms is strongly suggestive of aortic dissection involving the proximal aortic arch. The finding of aortic insufficiency is consistent with involvement of the proximal ascending aorta. A chest radiograph should also be obtained. It is likely to show a widened mediastinum with aortic knob intimal calcium separated from the adventitial border by 1.2 cm. This “calcium sign” is defined as a separation that exceeds 1.0 cm, and it is pathognomonic for aortic dissection. An ECG should also be obtained to determine
    if there is an acute MI, which may result from occlusion of the coronary artery by the dissection. In this patient, the ECG shows diffuse, nonspecific ST-segment and T-wave changes. On the basis of the history of “tearing” pain and these findings, the likelihood of aortic dissection is deemed high in this patient.


  • How are aortic dissections classified, what are the causes, and what are the common signs and symptoms?

    Several classifications for aortic dissection have been proposed, but the most commonly used is the following DeBakey classification:



    • Type I: Dissection originating in the ascending aorta, extending to or beyond the aortic arch


    • Type II: Dissection limited to the ascending aorta


    • Type III: Dissection originating in the descending aorta and extending distally down the aorta or, rarely, extending retrograde into the aortic arch and ascending aorta

    Another classification is the Daily or Stanford scheme that is simpler, and as follows:



    • Type A: All dissections involving the ascending aorta, regardless of the site of origin


    • Type B: All dissections not involving the ascending aorta

    DeBakey types I and II and Stanford A both involve the ascending aorta and are termed proximal dissections, and DeBakey III and Stanford B involve the descending aorta and are termed distal dissections.

    The treatment of aortic dissection depends on whether the dissection involves the proximal or distal aorta. The clinical manifestations are determined by involvement of arterial branches of the aorta (the right brachiocephalic artery in this patient), the aortic valve (aortic insufficiency in this patient) or coronary arteries, or both. A dissection that reaches proximally into the pericardial space can cause tamponade. Approximately two thirds of aortic dissections are proximal, whereas one third is distal.

    The etiology of nontraumatic aortic dissection involves degeneration of the collagen and elastin fibers of the media of the aorta, which usually occurs in patients experiencing a chronic arterial stress, such as hypertension. A specific type of medial degeneration called cystic medial necrosis occurs in patients with Marfan’s and Ehlers-Danlos syndromes.

    Other predisposing factors for dissection include congenital coarctation of the aorta, bicuspid aortic valve, atherosclerosis, Noonan’s and Turner’s syndromes, and giant cell arteritis. Direct external trauma as well as intravascular trauma due to arterial catheterization and intraaortic balloon pumps may result in aortic dissection. Aortic trauma during cardiac surgery, especially aortic valve replacement, may rarely result in dissection.

    The incidence of aortic dissection peaks in the sixth and seventh decades. There is a preponderance of male patients with a male-to-female ratio of 2:1.

    The most common symptom at presentation, seen in more than 90% of patients, is sudden onset of severe chest pain that is immediately maximal in intensity. The pain is unbearable, and often described as a sharp, tearing or ripping sensation. This differentiates it from that of an MI, which is frequently crescendo in nature and
    pressure-like. The pain can migrate usually following the path of dissection. Anterior chest pain is usually associated with a proximal dissection, whereas an interscapular pain indicates a distal dissection. The differential diagnosis of aortic dissection includes MI or ischemia, a thoracic nondissecting aneurysm, musculoskeletal pain, mediastinal tumors, and pericarditis.

    Other signs and symptoms of acute aortic dissection depend on involvement of major arterial branches or the aortic valve and are more common with proximal dissection. Aortic insufficiency occurs in up to two thirds of all cases of proximal dissection and is due to dilation of the aortic root, hematoma interfering with leaflet coaptation, tearing of the annulus or leaflet, or a combination of these. Aortic insufficiency is the most common cause of HF in these patients. Neurologic deficits can include stroke, paraplegia, or altered consciousness. Other complications include Horner syndrome resulting from superior cervical ganglion compression and left recurrent laryngeal nerve paralysis causing hoarseness. The involvement of major arterial branches can lead to myocardial, mesenteric, or renal infarctions.

    Rupture of an aortic dissection is more common with the proximal type and can cause acute hemopericardium with cardiac tamponade or a left pleural effusion. Rupture into the airways or esophagus can result in hemoptysis or hematemesis.


  • What initial therapy is indicated to stabilize this patient’s condition?

    Medical therapy is indicated initially to stop the progression of the dissection. The patient should be admitted to an intensive care unit with hemodynamic monitoring. Medical therapy is aimed at reducing the mean arterial blood pressure and the velocity of the left ventricular ejection (arterial dP/dt) to minimize arterial shear stress.

    Sodium nitroprusside is a direct vasodilator and decreases arterial pressure in a dose-dependent manner. The aim is to reduce systolic blood pressure to 100 to 120 mm Hg as long as there is adequate organ perfusion. Nitroprusside increases dP/dt if used alone and the administration of β-blocking agents blunts this effect. If there are no contraindications to β-blockers, they should be given intravenously to reach a heart rate of 60 to 80 beats per minute. Esmolol, a short-acting IV β-blocker, may be particularly useful because it can be titrated minute-to-minute to reduce heart rate. Labetalol is also a good choice for the treatment of acute aortic dissection because it is both an α- and β-blocking drug. In patients who have a contraindication to β-blockers, calcium channel blockers such as verapamil or diltiazem delivered by IV route could be used to decrease heart rate and blood pressure.


  • Because aortic dissection is thought to be present, what imaging techniques should be done to confirm the diagnosis of aortic dissection and assist in planning further therapy?

    A transthoracic echocardiogram is a quick and noninvasive modality to confirm aortic insufficiency, assess segmental left ventricular systolic function, and assess the proximal aortic root for the presence of dilation. However, it has poor sensitivity especially for distal dissections. In general, TEE, CT, and MRI are the imaging modalities used to detect dissection.

    TEE is much more sensitive for the detection of dissection, likely the most sensitive of the imaging modalities. It is limited, however, in its capability to assess the distal ascending aorta and the proximal arch. It can assess the proximal aorta, the degree
    of aortic insufficiency, left ventricular function, the presence of pericardial effusion, and often permits visualization of the proximal coronary arteries. Therefore, it offers a more complete assessment of the disease and its complications. In hemodynamically unstable patients, this test can be quickly performed at the bedside while treatment is being provided concomitantly, making it the procedure of choice in this instance.

    MRI is highly sensitive and specific in assessing these patients and can visualize the entire thoracic aorta in one view. Using gadolinium, the presence of aortic insufficiency as well as involvement of major branch vessels can be assessed in a large number of patients (i.e., the subclavian or carotid artery). This technique cannot be used in patients with pacemakers and defibrillators. MRI scanners limit access to the patient during the test for up to 30 to 40 minutes, which is disadvantageous in unstable patients.

    A contrast CT scan (especially helical CT) is good for defining the extent of an aortic dissection, that is, proximal versus distal. CT angiography can also assess involvement of major aortic branches. Its major advantages are very high sensitivity and availability. A disadvantage is that it rarely defines the site of the intimal tear.

    The previous gold standard for the diagnosis of aortic dissection was aortography. This modality can define the site of the intimal tear, the severity of aortic insufficiency, coronary artery involvement, and the extent of the dissection—proximal versus distal. However, aortography has been shown to have a lower sensitivity compared with the other modalities discussed above. Therefore, the current gold standard varies depending on the availability of imaging modalities. A helical CT is available in most institutions and is very accurate. A TEE, especially in unstable patients, has been recommended as the first test by the European Society of Cardiology. MRI is considered by many as the first test to be performed but is not always available.


  • What definitive therapy should be instituted?

    Untreated acute aortic dissection is associated with 25% mortality at 24 hours and a death rate of more than 75% at 1 month. In general, surgical repair is preferred for acute proximal dissection or in distal dissections when vital organ or limb compromise is present, for rapid expansion or formation of a saccular aneurysm, for rupture, in the presence of uncontrolled pain, or in patients with Marfan’s syndrome. Medical therapy (reducing the blood pressure and dP/dt) is adequate for uncomplicated acute distal dissections as there is less risk of complications. It is also recommended in chronic (present for >2 weeks) proximal or distal dissections as these patients have survived the period of highest mortality risk.


  • What long-term care is indicated for this patient?

    It is essential to rapidly control the patient’s hypertension and decrease the rate of pressure rise in the left ventricle, preferably with βblockers. The long-term prognosis in hospital survivors is good, with an actuarial survival rate only slightly worse than that for age-matched subjects. The type of dissection or therapy used does not influence the outcome after discharge from the hospital. The highest risk for recurrent dissection or aneurysm expansion is in the first 2 years. Careful follow-up during this initial period is important to ensure adequate blood pressure control and monitor for recurrence. This would include physical examination and chest x-rays. Serial imaging with CT scanning, TEE, or MRI should also be part of this follow-up.




Suggested Readings

Hagan PG, Nienaber CA, Isselbacher EM, etal. The international registry of acute aortic dissection (IRAD): new insights into an old disease. 2000;283(7):897–903.

Nienaber CA, Eagle KA. Aortic dissection: new frontiers in diagnosis and management: part I: from etiology to diagnostic strategies. Circulation 2003;108:628–635.

Nienaber CA, Eagle KA. Aortic dissection: new frontiers in diagnosis and management: Part II: therapeutic management and follow up. Circulation 2003;108:772–778.

Sabik JF, Lytle BW, Blackstone EH, etal. Long-term effectiveness of operations for ascending aortic dissections. J Thorac Cardiovasc Surg 2000;119(5):946–962.


Chronic Heart Failure



  • What are the most common underlying diseases causing chronic HF in the U.S. population?


  • Is HF always associated with a decreased ejection fraction (EF)?


  • What is myocardial remodeling and what are its consequences?


  • Which drug classes have been shown to prolong survival in patients with HF?


  • What devices have been shown to prolong survival in patients with HF?


Discussion



  • What are the most common underlying diseases causing chronic HF in the U.S. population?

    In the United States and most developed countries, hypertension and ischemic heart disease are the most common causes of HF. Valvular heart disease and cardiomyopathy are less common causes, but are still frequently encountered.


  • Is HF always associated with a decreased EF?

    Systolic dysfunction is defined as a decrease in contractile function most commonly measured as a decrease in EF. Many patients with HF have a decreased EF. However, almost half of all patients with HF have a normal EF. In some of these patients, diastolic dysfunction is the cause. Diastolic dysfunction results when the heart is stiff and ventricular filling is impaired, resulting in increased end-diastolic pressures. Patients may have diastolic dysfunction with or without systolic dysfunction. Typical signs and symptoms of HF occur with either normal or abnormal EF. Typically, the prevalence of HF with a normal EF is most common in elderly women.


  • What is myocardial remodeling and what are its consequences?

    After myocardial injury with resulting systolic dysfunction, there is often a progressive deterioration in the structure and function of the ventricular myocardium—a process termed myocardial remodeling. Myocardial remodeling is characterized by progressive ventricular enlargement and decreasing EF. This progressive remodeling is at least partially responsible for the high
    mortality rates in patients with HF. Although the specific molecular and cellular events that lead to remodeling are not entirely understood, many factors that promote remodeling have been described. These mechanisms include increased wall stress and activation of the renin–angiotensin and β-adrenergic systems. Blockade of these systems would be expected to slow or prevent myocardial remodeling and improve survival in patients with HF and systolic dysfunction.


  • Which drug classes have been shown to prolong survival in patients with HF?

    In patients with HF due to a decreased EF, ACE inhibitors and β-adrenergic receptor antagonists β-blockers) have been shown to improve survival. Angiotensin-receptor blockers (ARBs) are probably equivalent to ACE inhibitors and may be substituted, especially if there is intolerance to ACE inhibitors due to cough. Either aldosterone antagonists or ARBs also improve survival when added to ACE inhibitors and β-blockers, but care must be taken to monitor patients carefully to avoid hyperkalemia; the use of all four drug classes together is not advised for most patients because of the risk of hyperkalemia. Digoxin may be helpful to improve symptoms but does not improve survival. Loop diuretics such as furosemide, bumetanide, and torsemide clearly relieve congestion caused by salt and water retention but have not been shown to improve survival. The combination of hydralazine and isosorbide dinitrate improves survival in African Americans with systolic dysfunction and New York Heart Association (NYHA)’s class III—IV HF.

    In patients with HF and normal EF only one major trial has been conducted. This trial using the ARB candesartan did not show a significant benefit on hospitalization or mortality rate. Loop diuretics are valuable in relieving congestive symptoms in these patients but no clinical trials have been conducted.


  • What devices have been shown to prolong survival in patients with HF?

    Patients with significant systolic dysfunction (EF ≤35%), and NYHA class II-III heart failure have improved survival when an internal cardiac defibrillator (ICD) is implanted. The ICD detects serious ventricular arrhythmias and corrects them either with pacing or a shock. Cardiac resynchronization therapy (CRT) is based on the concept that patients with left ventricular systolic dysfunction often have ventricular dyssynchrony. Dyssynchrony is most often seen when the QRS duration is 120 milliseconds or more and most clinical trials have used this QRS duration as an entry criteria. Dyssynchrony means that the left ventricular contraction is discoordinated, resulting in a lower stroke volume and increased wall stress. By pacing both the ventricular septum (with a pacer in the right ventricular apex) and the lateral wall of the left ventricle (through a pacer advanced through the coronary sinus into a lateral coronary vein) the coordination of ventricular contraction is improved, increasing cardiac output. In patients with an EF of 35% or less and HF, CRT improves symptoms, hospitalizations, and mortality.




Case Discussion



  • Does this patient have left, right, or biventricular failure?

    This patient has findings indicating both right and left ventricular failure (biventricular failure). The cool extremities, tachycardia, and narrow pulse pressure suggest poor forward cardiac output and could reflect either right or left ventricular failure. A left ventricular S3 gallop and pulmonary rales are signs of left ventricular
    failure. The bibasilar dullness suggests the presence of bilateral pleural effusions, which may be seen in the setting of either right or left ventricular dysfunction. The apical murmur most likely represents mitral regurgitation because it is loudest at the apex, it radiates to the axilla, and it does not change with respiration. We do not know from the history whether the patient had a preexisting valvular disorder. Secondary mitral or tricuspid regurgitation occurs commonly in patients with ventricular enlargement and dysfunction due to distortion of the supporting structures of the atrioventricular valves. Tricuspid regurgitation causes a large V wave in the jugular venous pulse.

    There are many signs of right ventricular failure in this patient. Elevated central venous pressure is apparent from the patient’s jugular venous distention. Kussmaul’s sign is the lack of a fall in the jugular venous pressure with inspiration and is due to the right ventricle’s inability to handle the augmented venous return. It may be encountered in patients with right ventricular failure or constrictive pericardial disease. The patient’s enlarged liver is the result of hepatic congestion stemming from increased back pressure on the hepatic vein. The pitting edema in the lower extremities is caused by elevated hydrostatic pressure in the venous system, resulting in extravasation of fluid into the interstitial space of the ankles, where the forces of gravity are the greatest.


  • An S3 is heard, but no S4. Why?

    An S3 is a low-frequency sound heard 0.13 to 0.16 second after S2. An S3 occurs at the end of the rapid phase of ventricular filling and is most likely due to the vibration of the chordae tendineae or the left ventricular wall with rapid filling, and may arise from the right or left ventricle. A left ventricular S3 is best heard with the bell of the stethoscope at the cardiac apex. A right ventricular S3 is also best heard with the bell, but is most audible at the lower left sternal border or over the epigastrium. An S3 is a normal finding in children or young adults, but in middle-aged or older patients it is usually a sign of volume overload most often due to HF, as it is in this patient.

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Jul 8, 2016 | Posted by in GENERAL & FAMILY MEDICINE | Comments Off on Cardiology

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