Diastolic dysfunction overview

Diastolic dysfunction Microchapters
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Overview
Classification
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Differentiating Diastolic dysfunction from other Diseases
Epidemiology and Demographics
Natural History, Complications and Prognosis
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Diagnostic Criteria
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Physical Examination
Laboratory Findings
Echocardiography
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Assistant Editor(s)-in-Chief: Rim Halaby

Overview

Congestive heart failure and cardiac dysfunction are not interchangeable definitions. Whereas heart failure is a clinical definition that illustrates the occurrence of symptoms of fatigue, dyspnea, and fluid overload; cardiac dysfunction is a mechanical definition that includes abnormalities in heart contraction (called systolic dysfunction) or abnormalities in heart relaxation and filling (called diastolic dysfunction) or both.

Therefore, diastolic dysfunction refers to a mechanical dysfunction of the heart during the diastolic phase of the cardiac cycle in the presence or absence of any clinical symptoms. When clinical symptoms are present on top of the mechanical dysfunction of the heart, the condition is called diastolic heart failure.

Diastole is the phase of the cardiac cycle when the heart ( i.e. ventricle) is not contracting but is actually relaxed and filling with blood that is being returned to it, either from the body (into right ventricle) or from the lungs ( into left ventricle). The mechanical abnormality in diastolic dysfunction is characterized by a decrease in the ventricular filling in the context of an elevated left ventricular end diastolic pressure and a normal ejection fraction.

Diastolic dysfunction is caused by decrease cardiac muscle relaxation or increased stiffness. The ejection fraction of the heart is preserved in this type of dysfunction.

Systolic and diastolic dysfunction commonly occur in conjunction with each other.

Classification

Grade I

The mildest form is called an "abnormal relaxation pattern", or grade I diastolic dysfunction. On the mitral inflow Doppler echocardiogram, there is reversal of the normal E/A ratio. This pattern may develop normally with age in some patients, and many grade I patients will not have any clinical signs or symptoms of heart failure.

Grade II

Grade II diastolic dysfunction is called "pseudonormal filling dynamics". This is considered moderate diastolic dysfunction and is associated with elevated left atrial filling pressures. These patients more commonly have symptoms of heart failure, and many have left atrial enlargement due to the elevated pressures in the left heart.

Grade III

Grade III diastolic dysfunction is associated with "restrictive filling dynamics". This is a severe forms of diastolic dysfunction, and patients tend to have advanced heart failure symptoms.

Class III diastolic dysfunction patients will demonstrate reversal of their diastolic abnormalities on echocardiogram when they perform the Valsalva maneuver. This is referred to as "reversible restrictive diastolic dysfunction".

Grade IV

Grade III diastolic dysfunction is associated with "restrictive filling dynamics". This is a severe forms of diastolic dysfunction, and patients tend to have advanced heart failure symptoms.

Class IV diastolic dysfunction patients will not demonstrate reversibility of their echocardiogram abnormalities, and are therefore said to suffer from "fixed restrictive diastolic dysfunction".

Pathophysiology

Diastolic dysfunction is the impairment of the heart muscle in its ability to properly relax and fill with blood during diastole. Diastolic dysfunction is mainly the result of either impaired myocardial relaxation or increased cardiac muscle stiffness. As a result, the pressure in the left ventricle increases at the end of diastole and causes a build up of pressure in the left atrium and consequently in the pulmonary circulation. The result is pulmonary edema and dyspnea.

Normally, with reference to the left side of the heart, blood flows from the lungs, into the pulmonary veins, into the left atrium, through the mitral valve, and finally into the left ventricle. Diastolic dysfunction is the inability of the heart to properly relax and fill with blood during diastole.

Underlying Causes of Diastolic Dysfunction

Impaired extent and/or speed of myocardial relaxation

• Myocardial relaxation is an ATP dependent process regulated by the rate of re-uptake of cytoplasmic calcium into the sarcoplasmic reticulum.
• Low concentration of calcium, as seen in ischemia, is associated with a slowed down myocardial relaxation.

Increased myocardial stiffness

• Myocardial stiffness can be secondary to cardiac muscle hypertrophy (for example as seen in hypertension). Concentric hypertrophy (increased mass and relative wall thickness) and remodelling (normal mass but increased wall thickness) are associated with diastolic dysfunction due to impaired filling.
• Myocardial stiffness can be the result of infiltrative diseases like amyloidosis.
• Scarred heart muscle, occurring after a heart attack, are relatively stiff.
• Diabetes can be a cause of cardiac stiffness as a result of glycosylation of the heart muscle.

Extrinsic constraints

• Extrinsic constraints can be seen in pericardial compression.

Chamber dilatation

• Severe systolic dysfunction that has led to ventricular dilation can be associated with diastolic dysfunction. When the ventricle has been stretched to a certain point, any further attempt to stretch it more, as by blood trying to enter it from the left atrium, meets with increased resistance and thus decreased compliance.

Miscelleneous

• In mitral stenosis, blood cannot readily flow out from the left atrium into the left ventricle since the valve between those two heart chambers is blocked which causes the blood to back up into the left atrium and, eventually, the lungs. Pulmonary edema may result.
• Diastolic dysunction secondary to mitral stenosis is especially seen when the heart rate is elevated, as occurs in exercise and pregnancy. Thus, there will be insufficient time for the blood to traverse the narrowed passageway (i.e. mitral valve) between the left atrium and left ventricle.

Sequence of Events in Diastolic Dysfunction

• Impaired cardiac muscle relaxation or/and decreased left ventricular compliance lead to delay in left ventricular filling.
• Left ventricular end diastolic pressure will become high.
• Pulmonary capillary pressure increases.
  • As a result of hydrostatic forces, this high pressure leads to leaking of fluid (i.e. transudate) from the lung's blood vessels into the air-spaces (alveoli) of the lungs. The result is pulmonary edema, a condition characterized by difficulty breathing, inadequate oxygenation of blood, and, if severe and untreated, death. Life threatening episodes of pulmonary edema can occur due to sudden decompensation. This is called flash pulmonary edema. The left ventricle diastolic pressure rises progressively prior to the acute onset failure.
• It is worth re-emphasizing that the pulmonary edema that can develop as a result of diastolic dysfunction is not due to poor pumping function of the left ventricle. Indeed, it has resulted from the left ventricle's inability to readily accept blood trying to enter it from the left atrium.
• In the setting of a stiff left ventricle, it is more difficult for blood to flow into it from the left atrium. In such a situation, filling can be maintained by a combination of coordinated left atrial pumping (i.e. beating) and a relatively slow heart rate. The former actively pumps blood into the stiff left ventricle, and the latter can allow for sufficient time for blood to passively enter the left ventricle from the left atrium.
• Conditions that increase the heart rate, for example exercise and pregnancy, decrease the diastolic filling time and hence worsens the diastolic dysfunction in the setting of a non-compliant heart.

Causes

In alphabetical order:

• Amyloidosis
• Aortic stenosis
• Constrictive pericarditis
• Diabetes
• Effusive-constrictive pericarditis
• Glycogen storage disease
• Hemochromatosis
• Hypereosinophilic syndrome
• Hypertrophic heart diseases(for example, as seen in hypertension)
• Hypertrophic obstructive cardiomyopathy (HOCM)
• Infiltrative diseases ( for example, amyloidosis)
• Ischemia
• Mitral stenosis
• Myocardial infarction and scar
• Pericardial effusion
• Restrictive cardiomyopathy
• Sarcoidosis
• Systolic dysfunction

Differentiation of Diastolic Dysfunction from Systolic Dysfunction

• Characteristics of systolic dysfunction:
  • Large, dilated, eccentrically hypertrophied ventricles
  • Impaired blood ejection during systole
  • Decreased cardiac output and ejection fraction
  • Normal or decreased blood pressure
  • Can occur in any age and more frequent in men than in women
  • Presence of S3 gallop
• Characteristics of diastolic dysfunction:
  • Small, thickened, concentrically hypertrophied ventricles
  • Large atria
  • Impaired blood filling during diastole
  • Normal ejection fraction
  • Systemic elevation of the blood pressure
  • Occurs mainly in elderly women
  • Presence of S4 gallop

Differentiation of Diastolic Dysfunction from other Disorders

• Cardiac tumors
• High output cardiac failure
• Mitral regurgitation
• Mitral stenosis
• Pericardial diseases - constrictive pericarditis, cardiac tamponade
• Right heart failure
• Valvular heart disease

Epidemiology and Demographics

The prevalence of diastolic dysfunction has increased and it is more common in females and the elderly.

Prognosis

Until recently, it was generally assumed that the prognosis for individuals with diastolic dysfunction and associated, intermittent pulmonary edema was better than those with systolic dysfunction. In fact, in two studies appearing in the New England Journal of Medicine in 2006, evidence was presented to suggest that the prognosis in diastolic dysfunction is the same as that in systolic dysfunction

Common Symptoms

The clinical manifestations of diastolic heart failure are as follows-

• Dyspnea on ordinary exertion or greater shortness of breath with usual activities
• Paroxysmal nocturnal dyspnea or awakening at night with shortness of breath
• Ankle edema or swelling of the feet and legs
• Orthopnea or sleeping on pillows
• Hemoptysis or frothy sputum
• Paroxysmal nocturnal dyspnea or awakening at night with shortness of breath
• Syncope or passing out
• Weakness

Less Common Symptoms

• Fainting
• Fatigue
• Syncope or passing out
• Life threatening flash pulmonary edema.

In a cross sectional survey of 2042 randomly selected residents of Olmstead County, Minnesota, diastolic dysfunction was often not accompanied by recognized CHF but was associated with marked increases in all-cause mortality. Thus, possibility of asymptomatic diastolic heart failure should also be kept in mind..

The manifestations of overt systolic and diastolic heart failure are similar. Patients with diastolic dysfunction may have an exacerbation of their symptoms in the following settings:

• Tachycardia, increased heart rate would hamper proper and complete filling of left ventricle.
• Hypertension, especially if it is acute in onset or refractory to treatment increases the stress on the walls of the ventricle, which in turn leads to hypertrophy and impaired filling.
• Atrial fibrillation leads to poor coordination between atrial and ventricular contraction and contributes to further reduction in filling.
• Acute ischemia, leads to diastolic dysfunction which increases left atrial pressure and causes pulmonary edema.

Physical Examination

In general, signs of both left sided heart failure and right sided heart failure are present. Signs that represent acute left sided failure include cool clammy skin, cyanosis, rales,and a gallop rhythm. Signs that represent right sided failure include an elevated JVP, pedal edema, ascites, hepatomegaly, a parasternal heave and hepatojugular reflux. Commonly signs of both left and right sided failure are present.

Laboratory Findings

Plasma brain natriuretic peptide (BNP) or N-terminal pro b-type natriuretic peptide (NT-proBNP) can be used to diagnose heart failure when diagnosis is unclear. BNP levels are lower in diastolic dysfunction when compared with systolic dysfunction.

Echocardiography

Echocardiography can be used to diagnose diastolic dysfunction. No one single echocardiographic parameter can confirm a diagnosis of diastolic heart failure. Multiple echocardiographic parameters have been proposed as sufficiently sensitive and specific, including mitral inflow velocity patterns, pulmonary vein flow patterns, E:A reversal, tissue Doppler measurements, and M-mode echo measurements (i.e. of left atrial size). Algorithms have also been developed which combine multiple echocardiographic parameters to diagnose diastolic heart failure.

Treatment

The chronic treatment of diastolic dysfunction involves aggressive management of the underlying disorder that is causing the diastolic dysfunction such as diabetes or hypertension. Mild diastolic dysfunction that is well tolerated requires no specific treatment. Rate control is an important part of the acute therapy of the patient with diastolic heart failure. It takes a longer period of time for a stiff left ventricle to fill, and therefore rate control is a critical part of the acute therapy of diastolic dysfunction.

Acute Treatment of Diastolic Heart Failure

Rate Control

It takes a longer period of time for a stiff left ventricle to fill, and therefore rate control is a critical part of the acute therapy diastolic dysfunction. Furthermore, in atrial fibrillation there is a failure of atrial kick to augment the filling of the left ventricle.

Diuresis

Diuresis may reduce acute volume overload.

Relief of Ischemia

Acute myocardial ischemia leads to diastolic dysfunction which increases left atrial pressure and causes pulmonary edema.

Chronic Treatment of Diastolic Heart Failure

Afterload Reduction

There is some evidence that calcium channel blocker drugs may be of benefit in reducing ventricular stiffness in some cases. Likewise, treatment with angiotensin converting enzyme inhibitors such as enalapril, ramipril, and other ACE inhibitors may be of benefit due to their effect on ventricular remodeling.

ACA/AHA 2009 Guidelines for the Diagnosis and Management of Heart Failure in Adults: Patients With Heart Failure and Normal Left Ventricular Ejection Fraction (DO NOT EDIT)

Class I

"1. Physicians should control systolic and diastolic hypertension in patients with heart failure and normal left ventricular ejection fraction, in accordance with published guidelines. (Level of Evidence: C)"

"2. Physicians should control ventricular rate in patients with heart failure and normal left ventricular ejection fraction and atrial fibrillation. (Level of Evidence: C)"

"3. Physicians should use diuretics to control pulmonary congestion and peripheral edema in patients with heart failure and normal left ventricular ejection fraction. (Level of Evidence: C)"

Class IIa

"1. Coronary revascularization is reasonable in patients with heart failure and normal left ventricular ejection fraction and coronary artery disease in whom symptomatic or demonstrable myocardial ischemia is judged to be having an adverse effect on cardiac function. (Level of Evidence: C)"

Class IIb

"1. Restoration and maintenance of sinus rhythm in patients with atrial fibrillation and heart failure and normal left ventricular ejection fraction might be useful to improve symptoms. (Level of Evidence: C)"

"2. The use of beta-adrenergic blocking agents, ACEIs, ARBs, or calcium antagonists in patients with heart failure and normal left ventricular ejection fraction and controlled hypertension might be effective to minimize symptoms of heart failure. (Level of Evidence: C)"

"3. The usefulness of digitalis to minimize symptoms of heart failure in patients with heart failure and normal left ventricular ejection fraction is not well established. (Level of Evidence: C)"