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 DIASTOLIC HEART FAILURE: DO MEASUREMENTS WORK? Alina Nicoara, MD, FASE Duke University Medical Center A lot of advancement into the understanding of diastolic function and how to diagnose it came from a better understanding of the physiology of diastole. As we all know diastole starts at aortic valve closure and includes four phases: isovolumic relaxation, rapid or early filling, diastasis or slow filling at slow heart rates and the final phase atrial contraction. In reality, diastole begins during the second half of systolic ejection when the relaxation of the subendocardium begins. Relaxation continues during isovolumic relaxation and into rapid filling. So even if the left ventricle starts to fill, in the normal heart the intraventricular pressure continues to decline creating that suction effect which accounts for 75-­‐80% of the filling occuring in early diastole. Relaxation depends on systolic events such as synchronicity, timing and velocity of contraction. On the other hand systolic performance depends on load and ventricular chamber geometry. Systole and diastole are highly interrelated and one cannot consider one independently of the other. There are two separate clinical entities related to diastolic events, which have emerged over the past two decades: diastolic dysfunction and diastolic heart failure. While a normal heart can fill at low pressures, when diastolic dysfunction occurs, the pressure-­‐volume relationship moves leftward and upward; the heart fills at relatively higher pressure, however a normal stroke volume is maintained. Patients with diastolic dysfunction are asymptomatic at rest; they may become symptomatic with exertion, tachyarrhythmias, or loss of atrial contraction. Diastolic heart failure (DHF) or heart failure with preserved ejection fraction (HFpEF) is a true heart failure syndrome, with effort intolerance, evidence of venous congestion and low cardiac output. HFpEF is a growing health problem associated with significant morbidity and associated with an increased risk of in-­‐hospital, short-­‐term and long-­‐term mortality. The prevalence of HFpEF is increasing out of proportion when compared with heart failure with reduced ejection fraction (HFrEF) and its prognosis is worsening. Among elderly women living in the community, HFpEF comprises 90% of incident heart failure cases. 60% of surgical patients 65 years of age or older have diastolic filling abnormalities with preserved ejection fraction. Therefore, diastolic dysfunction and diastolic heart failure represent underestimated pathology with a high risk of decompensation in the perioperative period due to arrhythmias, tachycardia, fluid shifts, myocardial ischemia, myocardial edema, or pericardial restraint. Short of performing cardiac catheterization and magnetic resonance imaging, echocardiography is the only modality that has proven versatile and reliable in both identifying those patients with heart failure on the basis of left ventricular diastolic dysfunction and excluding the presence of other cardiac conditions that can lead to heart failure with normal ejection fraction in the absence of diastolic dysfunction. Doppler measurements of transmitral and pulmonary veins flows, tissue Doppler imaging of the mitral annular velocities and color M-­‐mode of the transmitral flow have created the possibility of noninvasively evaluating diastolic function and filling properties. However, these techniques are complex and no single measurement on its own reflects diastolic function. Thus, a comprehensive assessment of a number of variables is required to evaluate diastolic function as correctly as possible. Staging of diastolic function according to the 2009 American Society of Echocardiography (ASE) recommendations for diastolic function evaluation: Doppler echocardiography also offers the possibility of diagnosing elevated left ventricular filling pressures. In HFpEF, the evaluation of filling pressures starts with the E/E’ ratio. A septal E/E’ ≥ 15 (lateral E/E’ ≥ 12, or average ≥ 13) has been found to indicate an elevated left atrial (LA) pressure, while a ratio <8 (septal, lateral, or average) is associated with normal LA pressures. In the intermediary range (E/E’ 9-­‐
14) an assessment of filling pressures should include other parameters (LA size, deceleration time, mitral inflow pattern, etc) Recognizing the limitations of the comprehensive algorithm in the intraoperative environment, Swaminathan et al investigated the feasibility and reliability of a simplified algorithm in a large retrospective study of diastolic function assessment by transesophageal echocardiography in patients undergoing surgical coronary artery revascularization. In this simplified algorithm, diastolic dysfunction was graded based only on the mitral annulus E’ velocity and the E/E’ ratio. Applying the ASE recommended algorithm only 60% of the patients included in the study were assigned a diastolic function grade; using the simplified algorithm, 99% of the patients were assigned a grade. However, any grading system is relevant only if it carries prognostic information and identifies patients at high risk for adverse outcomes. When comparing the prognostic value of the two algorithms, there was no significant discrimination among different grades of diastolic dysfunction assigned by the comprehensive algorithm and event-­‐free survival. On the other hand, the simplified algorithm had prognostic value showing that each grade of increasing diastolic dysfunction was associated with a higher risk of major cardiac adverse events. Originally thought to be due solely to left ventricular diastolic dysfunction, HFpEF is much more complex and several studies using newer measurements of left ventricular mechanics have shown that systolic function is not entirely normal. In a study assessing systolic function by longitudinal and circumferential strain by deformational analysis, both types of strain were reduced in patients with HFpEF compared to the control group with longitudinal strain being most abnormal. Reduced longitudinal strain was most common in the patients with ejection fraction in the lower range (45% to 54%) but was also present in 50% of the patients with normal ejection fraction. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. Gillebert TC, De Pauw M, Timmermans F. Echo-­‐Doppler assessment of diastole: flow, function and haemodynamics. Heart 2013;99:55-­‐64. Hayley BD, Burwash IG. Heart failure with normal left ventricular ejection fraction: role of echocardiography. Current opinion in cardiology 2012;27:169-­‐80. Bhatia RS, Tu JV, Lee DS et al. Outcome of heart failure with preserved ejection fraction in a population-­‐based study. The New England journal of medicine 2006;355:260-­‐9. Gelzinis TA. New Insights Into Diastolic Dysfunction and Heart Failure With Preserved Ejection Fraction. Seminars in cardiothoracic and vascular anesthesia 2013. Kitzman DW, Upadhya B. Heart failure with preserved ejection fraction: a heterogenous disorder with multifactorial pathophysiology. Journal of the American College of Cardiology 2014;63:457-­‐9. Kraigher-­‐Krainer E, Shah AM, Gupta DK et al. Impaired systolic function by strain imaging in heart failure with preserved ejection fraction. Journal of the American College of Cardiology 2014;63:447-­‐56. Matyal R, Hess PE, Subramaniam B et al. Perioperative diastolic dysfunction during vascular surgery and its association with postoperative outcome. Journal of vascular surgery 2009;50:70-­‐6. Nicoara A, Whitener G, Swaminathan M. Perioperative Diastolic Dysfunction: A Comprehensive Approach to Assessment by Transesophageal Echocardiography. Seminars in cardiothoracic and vascular anesthesia 2013. Owan TE, Hodge DO, Herges RM, Jacobsen SJ, Roger VL, Redfield MM. Trends in prevalence and outcome of heart failure with preserved ejection fraction. The New England journal of medicine 2006;355:251-­‐9. Paulus WJ, Tschope C, Sanderson JE et al. How to diagnose diastolic heart failure: a consensus statement on the diagnosis of heart failure with normal left ventricular ejection fraction by the Heart Failure and Echocardiography Associations of the European Society of Cardiology. European heart journal 2007;28:2539-­‐50. Swaminathan M, Nicoara A, Phillips-­‐Bute BG et al. Utility of a simple algorithm to grade diastolic dysfunction and predict outcome after coronary artery bypass graft surgery. The Annals of thoracic surgery 2011; 91:1844-­‐
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