Gross structural abnormalities Structural changes that occur with<unk>  are often radically different from those associated with<unk><unk>  with reduced<unk><unk>  <unk> . Many patients experience increased thickening of the ventricular wall in comparison to chamber size, termed concentric hypertrophy. This leads to increased left ventricular mass and is typically accompanied by a normal, or slightly reduced, end diastolic filling volume. Conversely,<unk>  is typically associated with eccentric hypertrophy, characterized by an increase in cardiac chamber size without an accompanying increase in wall thickness. This leads to a corresponding increase in left ventricular end diastolic volume. Cellular abnormalities Cellular changes generally underlie alterations in cardiac structure. In<unk>  cardiomyocytes have been demonstrated to show increased diameter without an increase in length; this is consistent with observed concentric ventricular hypertrophy and increased left ventricular mass.<unk>  cardiomyocytes exhibit the opposite morphology; increased length without increased cellular diameter. This too is consistent with eccentric hypertrophy seen in this condition. Changes in the extracellular environment are of significant importance in<unk>  disease. Particularly, regulation of genes that alter fibrosis contribute to the development and progression of<unk> . This regulation is dynamic and involves changes in fibrillar collagens through increased deposition as well as inhibition of enzymes that break down extracellular matrix components (matrix metalloproteinases, collagenases). While early stage<unk>  is associated with a significant disruption of extracellular matrix proteins initially, as it progresses fibrotic replacement of myocardium may occur, leading to scarring and increased interstitial collagen. Fibrotic changes in<unk>  are more variable. Though there is typically an increased amount of collagen observed in these patients it is usually not dramatically different from<unk> hy individuals. Diastolic dysfunction Wiggers diagram, depicting the cardiac cycle. Two complete cycles are illustrated. Diastolic alterations in<unk>  are the predominating factor in impaired cardiac function and subsequent clinical presentation. Diastolic dysfunction is multifaceted, and a given patient may express diverse combinations of the following: incomplete myocardial relaxation, impaired rate of ventricular filling, increased left atrial pressure in filling, increased passive stiffness and decreased distensibility of the ventricle, limited ability to exploit the Frank-Starling mechanism with increased output demands, increased diastolic left<unk>  or pulmonary venous pressure. Diastolic<unk>  appears when the ventricle cannot be filled properly because it cannot relax because its wall is thick or rigid. This situation presents usually a concentric hypertrophy. In contrast, systolic<unk><unk>  has usually an eccentric hypertrophy. Diastolic<unk>  is characterized by an elevated diastolic pressure in the left ventricle, despite an essentially normal/physiologic end diastolic volume (EDV). Histological evidence supporting diastolic dysfunction demonstrates ventricular hypertrophy, increased interstitial collagen deposition and infiltration of the myocardium. These influences collectively lead to a decrease in distensibility and elasticity (ability to stretch) of the myocardium. As a consequence, cardiac output becomes diminished. When the left ventricular diastolic pressure is elevated, venous pressure in lungs must also become elevated too: left ventricular stiffness makes it more difficult for blood to enter it from the left atrium. As a result, pressure rises in the atrium and is transmitted back to the pulmonary venous system, thereby increasing its hydrostatic pressure and promoting pulmonary edema. End Diastolic Pressure Volume Relationship It may be misguided to classify the volume-overloaded<unk>  as having diastolic dysfunction if it is behaving in a stiff and non-compliant manner. The term diastolic dysfunction should not be applied to the dilated<unk> . Dilated ("remodeled")<unk> s have increased volume relative to the amount of diastolic pressure, and therefore have increased (not decreased) distensibility. The term diastolic dysfunction is sometimes erroneously applied in this circumstance, when increased fluid volume retention causes the<unk>  to be over-filled (High output cardiac<unk> . Although the term diastolic<unk><unk>  is often used when there are signs and symptoms of<unk><unk>  with normal left ventricular systolic function, this is not always appropriate. Diastolic function is determined by the relative end diastolic volume in relation to end diastolic pressure, and is therefore independent of left ventricular systolic function. A leftward shift of the end-diastolic pressure-volume relationship (i.e. decreased left ventricular distensibility) can occur both in those with normal and those with decreased left ventricular systolic function. Likewise,<unk><unk>  may occur in those with dilated left ventricular and normal systolic function. This is often seen in valvular<unk>  disease and high-output<unk><unk> . Neither of these situations constitutes a diastolic<unk><unk> . Stiffening of the left ventricle contributes<unk> , a condition that can be prevented with exercise. In diastolic<unk><unk> , the volume of blood contained in the ventricles during diastole is lower than it should be, and the pressure of the blood within the chambers is elevated. Diastole During diastole, the ventricular pressure falls from the peak reached at the end of systole. When this pressure falls below the atrial pressure, atrio-ventricular valves open (mitral valve at left side and tricuspid valve at right side) and the blood passes from the atria into the ventricles. First, ventricles are filled by a pressure gradient but near the end, atria contract (atrial kick) and force more blood to pass into ventricles. Atrial contraction is responsible for around 20% of the total filling blood volume. (In atrial fibrillation, this additional 20% filling volume is lost and the patient may experience systolic<unk><unk>  symptoms). Complete left ventricular filling is essential to maintain maximum cardiac output. Left ventricular filling is dependent upon ventricular relaxation and compliance, mitral valve area, atrio-ventricular gradient, atrial contraction and end-systolic volume. Diastole has four phases: isovolumetric relaxation, rapid filling, diastasis and atrial contraction. All of these phases can be evaluated by Doppler echocardiography. Non-diastolic dysfunction Though<unk>  is characterized by a normal<unk><unk> , this parameter is a rather poor index of the<unk> 's contractile function. Some studies have shown that metrics of load independent contractility (such as left ventricular stiffness) reveal diminished systolic function in<unk>  patients compared to<unk> hy controls, and are corroborated by tissue Doppler findings that reveal changes in longitudinal contraction and motion abnormalities. While these systolic impairments may be minimal at rest, they become more exaggerated with increased demand, as seen in exercise. Pulmonary hypertension and right ventricular dysfunction Most<unk>  patients exhibit pulmonary hypertension which is significantly associated with increased morbidity and mortality. Left atrial and pulmonary venous pressure increases in<unk>  due to diastolic insufficiency thus increasing pulmonary artery pressure. In patients with advanced<unk>  changes in the pulmonary vasculature may develop, leading to pre-capillary pulmonary hypertension. Right ventricular dysfunction is also common in<unk>  patients, occurring in 20-35% of patients. This right ventricular dysfunction is more common in patients with more advanced<unk>  as well as those with pulmonary hypertension and lower<unk><unk> s.<unk>  rate Cardiac output is dependent on stroke volume and<unk>  rate. A significant portion (55-77%) of<unk>  patients are unable to increase<unk>  rate to compensate for increased output demand (as in the setting of exercise); this is termed chronotropic incompetence. Combined with the characteristic deficit in stroke volume observed in<unk>  patients, many individuals display poor exercise tolerance. Dyssynchrony Non-simultaneous contraction of the left and right ventricle, dyssychrony, is present in up to 58% of<unk>  patients. However, dyssynchrony is also common in<unk>  and its role in<unk>  in particular remains obscure. While therapies for dyssynchrony, such as biventricular pacing provide benefits to<unk>  patients, no benefit is appreciable in<unk>  patients at this time. Systemic abnormalities Patients with<unk> , in addition to cardiac abnormalities, display changes in (endothelial) microvascular function, skeletal muscle metabolism and in fat distribution and character throughout the body. The importance of these changes is demonstrated in that stable, non-decompensated patients seem to benefit from exercise; specifically increased VO2 max and exercise tolerance. However, this benefit appears to be derived from changes in muscle and vasculature as opposed to directly on the<unk> , which displays minimal change in output following exercise training.
Heart failure with preserved ejection fraction
Ischemic cardiomyopathy
Diabetic cardiomyopathy
Hypertrophic cardiomyopathy
Dilated cardiomyopathy
Restrictive cardiomyopathy
Alcoholic cardiomyopathy
Amyloid cardiomyopathy