Jieun Kim

W. Frank Peacock

Clinical Highlights

The most common ED presentation of patients with dilated cardiomyopathy is decompensated heart failure (HF). Dyspnea is the most common complaint. Other complaints suggesting HF include dyspnea on exertion, orthopnea, peripheral edema, weight gain, paroxysmal nocturnal dyspnea, cough, and fatigue. Because HF may be preceded by myocardial ischemia, risk factors for coronary artery disease should be ascertained. Conditions that worsen or precipitate HF should be considered in the differential diagnosis and include myocardial ischemia, uncontrolled hypertension, arrhythmias, dietary, and medication noncompliance. Physical examination assists in evaluating HF, with vital signs and airway stability being paramount. Pulmonary rales, peripheral edema, jugular venous distention, hepatojugular reflux, and the presence of extra heart sounds identify fluid overload. Skin mottling, indicating poor perfusion, is associated with increased acute mortality.

Appropriate testing includes an electrocardiogram (ECG) to evaluate myocardial ischemia, a chest x-ray (CXR) to assess for pulmonary edema, and lab testing for troponin, natriuretic peptide levels, renal function, electrolytes, and hemoglobin.

The salient differential diagnoses include other conditions manifesting as acute dyspnea (pulmonary embolism, chronic obstructive pulmonary disease exacerbation, or pneumonia), pathology presenting as acute volume overload or edema (eg, renal failure and liver failure), and pump failure resulting from acute myocardial infarction (AMI), acute valve dysfunction, or pericardial disease.

ED Care and Disposition

At initial presentation, the patient’s airway should be evaluated and the need for noninvasive ventilation or endotracheal intubation considered. Hypertensive HF responds remarkably well to vasodilation, which may be performed via sublingual nitroglycerin until intravenous (IV) access is obtained. IV nitroglycerin is well tolerated and large doses may be required for relief of symptoms. Patients may initially be in extremis and may require rapid resuscitation. Conversely, inotropes may be indicated in the setting of symptomatic hypotension. In the volume-overloaded patient, loop diuretics may be administered after blood pressure control has been obtained, but are not necessarily critical upon initial presentation due to relatively slow onset of effect.

Disposition is dependent on the interventions required, with ICU admission indicated if airway control or vasoactive agents are necessary. Additionally, comorbidities may also prompt similar placement. The presence of coexistent renal insufficiency is particularly ominous, and identifies a cohort in whom aggressive therapy is required, as does elevated troponin, unstable vital signs, or markedly high natriuretic peptide levels. The absence of these findings, coupled with initial hypertension and symptoms that respond to therapy, identifies a cohort that is likely to be successfully managed in a 24-hour short stay unit.

Pearls and Pitfalls

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  Failure to aggressively treat hypertension may result in respiratory arrest.

  
  
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  Negative natriuretic peptides effectively rule out the presence of myocardial strain. However, as ventricular strain occurs in many conditions (eg, AMI and acute pulmonary embolus), elevated levels must be considered in clinical context; natriuretic peptides are falsely lowered in obesity and elevated in renal injury.

Kristi Colbenson

Sean Collins

Clinical Highlights

Restrictive cardiomyopathy (RCM) is a biventricular diastolic dysfunction without ventricular dilation or hypertrophy. It is a rare form of heart failure (HF) caused by pathologic inflammation, thrombosis, infiltration, and fibrosis within the myocardium and endocardium. RCMs are classified as primary or secondary. These underlying disease processes lead to restrictive filling, reduced diastolic volume, and though systolic function is preserved, a reduced cardiac output. Patients clinically present with classic acute HF signs and symptoms (Table 7.1). Diagnostically, ECG findings include low voltage and conduction abnormalities. Unique to RCM is that the chest x-ray (CXR) lacks cardiomegaly until late in the disease when bi-atrial enlargement leads to the appearance of cardiomegaly. Bedside ultrasound will reveal a normal left ventricle with preserved systolic function. Formal echocardiogram findings include a restrictive pattern of ventricular filling (early diastolic filling velocity and decreased isovolumic relaxation time) with increased atrial contribution. Ultimate diagnosis lies in a myocardial biopsy.

The differential diagnosis includes aortic stenosis, cardiac tamponade, hypertrophic cardiomyopathy, hypertensive heart disease, and constrictive pericarditis. Nearly identical in presentation, differentiating constrictive pericarditis from RCM is difficult, but imperative, as constrictive pericarditis is curable through surgical intervention. Constrictive pericarditis will have a low natriuretic peptide level compared to elevated levels in RCM. Also, calcifications on CXR are specific for constrictive pericarditis.

ED Care and Disposition

The mainstay of treatment is supportive, as no existing treatment improves long-term outcome. The goals of therapy are to reduce symptoms of diastolic dysfunction while maintaining cardiac output and controlling for possible complications. Low to medium dose diuretics improve systemic and pulmonary congestion from diastolic dysfunction. However, cautious diuresis must be employed as RCM requires high diastolic pressures to maintain cardiac output. Small changes in filing pressures dramatically reduce cardiac index. Routine use of beta and calcium channel blockers is debatable in RCM due to deleterious effects on blood pressure and right ventricle function. However, in the setting of tachycardia, calcium channel blockers are used to improve rate control and maximize diastolic function by improving ventricular relaxation and increasing ventricular filling time.

Anatomic changes in RCM predispose patients to arrhythmias and thromboembolic events. Atrial fibrillation is the most common complication in RCM, and is disastrous due to loss of atrial contraction needed to maintain preload. First-line treatment is amiodarone, as it maintains cardiac output. Digoxin can be used, but is contraindicated in amyloidosis as it precipitates arrhythmias. Cardioversion must be used with caution as infiltrative processes damage the intrinsic pacemaker; thus, cardioversion may cause complete heart block. Patients with RCM are at increased risk for ventricular thrombus formation. Specifically, endocardial fibrosis can lead to progressive obliteration of the left ventricle from thrombus formation. Finally, treatment of the underlying disease process can be initiated in the emergency room through the use of high-dose steroids to treat underlying inflammation in Loeffler syndrome and sarcoidosis.

Pearls and Pitfalls

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  RCM presents as acute diastolic HF. Its pathophysiology is unique in that systolic function is preserved and there is a lack of ventricular dilation or hypertrophy.

  
  
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  Supportive care through diuresis must be performed with caution as high preloads are required to maintain cardiac output.

  
  
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  Anticipate arrhythmias due to infiltrative processes in the conduction pathways; because of this, cardioversion may lead to complete heart block.

Nicholas R. Phillips

Clinical Highlights

Hypertrophic cardiomyopathy (HCM) is an important diagnosis to consider in the ED. Previously known as idiopathic hypertrophic subaortic stenosis (IHSS) or hypertrophic obstructive cardiomyopathy (HOCM), this entity is the most common cause of sudden death in young athletes. It is defined by left ventricular hypertrophy that is not due to another secondary cause such as valvular disorders or hypertension. Familial HCM is inherited as an autosomal dominant trait and is a relatively common disorder affecting approximately 1 in 500 adults. There are numerous different mutations that can lead to HCM, each with differing amounts of severity and leading to varying degrees of abnormal accumulation of cardiac myocytes.