Chapter 22: Acute Heart Failure

INTRODUCTION

Acute heart failure covers a wide spectrum of illness, with symptoms ranging from a gradual increase in leg swelling, shortness of breath, or decreased exercise tolerance to the abrupt onset of pulmonary edema and respiratory distress. While the term congestive heart failure was historically used to describe volume overload, current terminology describes patients as having acute heart failure when they present with an acute exacerbation of chronic heart failure or when new-onset heart failure is diagnosed. Heart failure has a poor prognosis with an approximately 50% mortality rate within 5 years of initial diagnosis. The most common precipitating factors of acute heart failure are atrial fibrillation, acute myocardial infarction or ischemia, discontinuation of medications (diuretics), increased sodium load, drugs that impair myocardial function, and physical overexertion.

CLINICAL FEATURES

No single historical or physical finding is sensitive and specific enough to accurately diagnose acute heart failure in all patients. On physical examination, patients with acute heart failure may present with dyspnea, frothy pink sputum, or respiratory distress. Patients are frequently tachycardic and hypertensive, and a third heart sound (S3) may be identified on auscultation. Abdominojugular reflux and jugular venous distension may also be seen.

Acute heart failure can be further classified as follows:

1. Hypertensive acute heart failure is characterized by signs and symptoms of acute heart failure with relatively preserved left ventricular function, systolic blood pressure >140 mmHg, a chest radiograph compatible with pulmonary edema, and symptom onset less than 48 hours.

2. Pulmonary edema presents with respiratory distress, rales on chest auscultation, reduced oxygen saturation from baseline, and characteristic chest radiograph findings.

3. Cardiogenic shock is characterized by evidence of tissue hypoperfusion and systolic blood pressure <90 mmHg.

4. Acute-on-chronic heart failure has signs and symptoms of acute heart failure that are mild to moderate and do not meet criteria for hypertensive heart failure, pulmonary edema, or cardiogenic shock. Systolic blood pressure is typically <140 mmHg and >90 mmHg, associated with increased peripheral edema, and has symptom onset over several days.

5. High-output failure presents with high cardiac output, tachycardia, warm extremities, and pulmonary congestion.

6. Right heart failure is a low-output syndrome with jugular venous distention, hepatomegaly, and variable hypotension.

DIAGNOSIS AND DIFFERENTIAL

Commonly, patients with acute heart failure present with dyspnea and the differential diagnosis may include other conditions such as COPD, asthma, pneumonia, pneumothorax, pleural effusion, pulmonary embolus, and acute coronary syndrome. There is no single diagnostic test for heart failure; it is a clinical diagnosis based on the history, physical examination, and diagnostic testing. The most useful historical parameter is a history of acute heart failure. The symptom with the highest sensitivity for diagnosis is dyspnea on exertion (84%) and the most specific symptoms are paroxysmal nocturnal dyspnea, orthopnea, and edema (77% to 84%).

Chest radiographs showing pulmonary venous congestion, cardiomegaly, and interstitial edema are the most ...