In recent years, diastolic function has received greater recognition for its impact on overall cardiac performance. Diastole is no longer regarded as a passive phase of the cardiac cycle, but rather as a complex sequence of interrelated events, which are dependent on loading conditions, heart rate, and contractility, and ultimately influence the systolic function of the left ventricle (LV). Studies have suggested that patients with diastolic dysfunction presenting for cardiac surgery are prone to hemodynamic instability and potentially worse outcomes1 and that patients with diastolic heart failure are at increased risk for decompensation in the perioperative period.2 Therefore, the perioperative echocardiographer should be familiar with the pathophysiology of diastolic heart failure and understand how to monitor and optimize diastolic function. Although advances in ultrasound technology have rendered Doppler echocardiography the clinician's “Rosetta Stone” for diastolic function evaluation, this chapter will familiarize readers with all the echocardiographic techniques routinely employed to assess LV diastolic function, as well as more modern and sophisticated methods of diastolic function assessment, explain the significance of these diastolic indices, and provide a diagnostic algorithm to evaluate perioperative diastolic function.
CLINICAL IMPORTANCE OF DIASTOLIC DYSFUNCTION
Diastolic dysfunction is defined as the inability to fill the LV to an adequate end-diastolic volume at a normal left atrial (LA) pressure. It represents a mechanical dysfunction of the LV, characterized by either impaired relaxation only or impaired relaxation and decreased compliance. Diastolic dysfunction may be absent at rest and may be unmasked by exercise, stress, or various perioperative events (tachycardia, pneumoperitoneum, positive pressure ventilation).3 Additionally, diastolic dysfunction may be present despite the absence of clinical signs and symptoms of heart failure. When these symptoms occur, the diagnosis of diastolic heart failure (or heart failure with preserved ejection fraction [EF]) is made. Therefore, whereas diastolic dysfunction describes a cardiac mechanical abnormality, diastolic heart failure represents a clinical syndrome.
Heart failure has an increasing prevalence in the United States.4 If current trends continue, 8.5 million Americans will suffer heart failure in 2030.5 Presently, heart failure is the most common cause of hospital admission in patients over 65 years of age, accounting for approximately 1 million admissions annually in the United States at a cost exceeding $15 billion.6 Nearly half of these patients, however, have a preserved EF.7 The prevalence of diastolic heart failure is age dependent, increasing from less than 15% in patients younger than 45 years of age to 35% in those between the ages of 50 and 70 years, and more than 70% in patients older than 70 years.8 The increased prevalence of diastolic dysfunction in the elderly appears to be related to the coexistence of diseases associated with aging such as hypertension, coronary artery disease, aortic stenosis, and cardiomyopathies that alter the normal LV structure and lead to deterioration of the LV diastolic properties. However, the etiology of heart failure with preserved EF ...