Acute Cardiorenal Syndrome

Abstract

Cardiorenal syndromes are broadly defined as disorders of the heart and kidneys whereby acute or chronic dysfunction in one organ may induce acute or chronic dysfunction of the other. The syndromes represent the intersection and overlap of two very common conditions facing practitioners, and an understanding of the complex bidirectional interactions of these organ systems is paramount for their management. In this chapter, we focus on the common situation whereby patients with acute decompensated heart failure or acute coronary syndrome experience abrupt worsening of kidney function known as acute kidney injury. This has been termed acute cardiorenal syndrome. This chapter reviews the definition, epidemiology, pathophysiology, manifestations, and treatment of acute cardiorenal syndrome, highlighting the need for further breakthroughs in management of this condition.

Keywords

cardiorenal syndrome, acute kidney injury, heart failure, acute decompensated heart failure, acute coronary syndrome

Cardiorenal syndromes are broadly defined as disorders of the heart and kidneys, whereby acute or chronic dysfunction in one organ induces acute or chronic dysfunction of the other. The syndromes represent the intersection and overlap of two very common conditions, heart disease and kidney disease, and an understanding of the complex bidirectional interactions of these organ systems is paramount for their management.

In this chapter, we focus on the common situation whereby patients with acute decompensated heart failure (ADHF) or acute coronary syndrome (ACS) experience abrupt worsening of kidney function known as acute kidney injury (AKI). This is termed acute cardiorenal syndrome (CRS). Other types of CRS include a more indolent form of chronic kidney disease arising in patients with longer term heart failure, termed chronic CRS. This and additional subtypes are highlighted in Box 29.1 but are not discussed in this chapter.

Box 29.1

Definition and Classification of the Cardiorenal Syndromes

Cardiorenal Syndromes

General Definition

Disorders of the heart and kidneys, whereby acute or chronic dysfunction in one organ may induce acute or chronic dysfunction in the other

Acute CRS (Type 1)

Acute worsening of cardiac function leading to kidney dysfunction

Chronic CRS (Type 2)

Chronic abnormalities in cardiac function leading to kidney dysfunction

Acute Renocardiac Syndrome (Type 3)

Acute worsening of kidney function causing cardiac dysfunction

Chronic Renocardiac Syndrome (Type 4)

Chronic abnormalities in kidney function leading to cardiac disease

Secondary CRS (Type 5)

Systemic conditions causing simultaneous dysfunction of the heart and kidney

CRS , Cardiorenal syndrome.

Definition and Epidemiology of Acute Cardiorenal Syndrome

Acute CRS is defined as an acute worsening of cardiac function leading to kidney dysfunction. ADHF can represent acute presentation of de novo heart failure or, more frequently, acute decompensation of chronic heart failure and typically is characterized by rapid worsening of the typical signs and symptoms of heart failure (shortness of breath, pulmonary rales, congestion on chest radiograph, raised jugular venous pressure, and peripheral edema), as highlighted in Box 29.2 and Table 29.1 . However, heart failure is a heterogeneous condition with various clinical presentations and multiple contributing factors. Although depressed left ventricular function is an important feature of heart failure, many patients presenting with ADHF have preserved left ventricular ejection fraction, and in roughly one-third of patients, ACS precipitates the decompensation. Accordingly, the hemodynamic derangements found in patients with ADHF are highly variable and to certain degrees overlapping, potentially including acute pulmonary edema with hypertension, severe peripheral fluid overload, isolated severe right heart failure with hepatic congestion, ascites and edema, cardiogenic shock, hypotension, and so on ( Fig. 29.1 ). The European Society of Cardiology (ESC) schematic for characterizing patients based on presence or absence of congestion (“wet” or “dry”) and hypoperfusion (“cold” or “warm”) is depicted in Table 29.2 . In addition, Table 29.3 lists the ESC diagnostic criteria and presenting clinical phenotypes of the various heart-failure syndromes as relating to reduction or preservation of ejection fraction.

Box 29.2

Definition of Heart Failure

Heart failure is a clinical syndrome in which patients have the following features:

•

Symptoms typical of heart failure
- •
  
  Breathlessness at rest or on exercise, fatigue, tiredness
•

Signs typical of heart failure
- •
  
  Tachycardia, tachypnea, pulmonary rales, pleural effusion, raised jugular venous pressure, peripheral edema, hepatomegaly
•

Objective evidence of a structural or functional abnormality of the heart at rest
- •
  
  Cardiomegaly, third heart sound, cardiac murmurs, abnormality on echocardiogram, raised concentration of natriuretic peptide

Modified from the 2008 European Society of Cardiology Guidelines for the Diagnosis and Treatment of Acute and Chronic Heart Failure.

Table 29.1

Common Clinical Manifestations of Heart Failure

Dominant Clinical Features	Symptoms	Signs
Peripheral edema/congestion	Breathlessness Tiredness, fatigue Anorexia	Peripheral edema Raised jugular venous pressure Pulmonary edema Hepatomegaly, ascites Fluid overload (congestion) Cachexia
Pulmonary edema	Severe breathlessness at rest	Pulmonary crackles, effusion Tachycardia, tachypnea
Cardiogenic shock (low cardiac output state)	Confusion Weakness Cold periphery	Poor peripheral perfusion Systolic blood pressure less than 90 mm Hg Anuria or oliguria
High blood pressure (hypertensive heart failure)	Breathlessness	Usually elevated blood pressure Left ventricular hypertrophy Preserved ejection fraction
Right heart failure	Breathlessness Fatigue	Evidence of right ventricular dysfunction Raised jugular venous pulsation Peripheral edema, hepatomegaly

Adapted from the 2008 European Society of Cardiology Guidelines for the Diagnosis and Treatment of Acute and Chronic Heart Failure.

Table 29.2

Clinical Profiles of Patients With Acute Heart Failure

	Congestion Absent	Congestion Absent
Hypoperfusion absent	Warm-Dry	Warm-Wet
Hypoperfusion present	Cold-Dry	Cold-Wet

Congestion present is defined by the presence of pulmonary or peripheral edema, orthopnea or paroxysmal nocturnal dyspnea, peripheral (bilateral) edema, jugular venous dilatation, congestive hepatomegaly or hepatojugular reflux, or gut congestion or ascites. Hypoperfusion is suggested by cool and sweaty extremities, oliguria, confusion, lightheadedness, or narrow pulse pressure.

Adapted from the European Society of Cardiology; Heart Failure Association of the ESC (HFA); et al. ESC guidelines for the diagnosis and treatment of acute and chronic heart failure 2016. Eur Heart J. 2016;37:2129–2200.

Table 29.3

Definition of Heart Failure With Preserved, Midrange, and Reduced Ejection Fraction

Type of HF	HFrEF	HFmrEF	HFpEF
Criteria	Symptoms ± signs	Symptoms ± signs	Symptoms ± signs
	LV ejection fraction <40%	LV ejection fraction 40%–49%	LV ejection fraction ≥50%
		Elevated natriuretic peptides	Elevated natriuretic peptides
		Structural heart disease and/or diastolic dysfunction	Structural heart disease and/or diastolic dysfunction