Diastolic Ventricular Interaction and Ventricular Diastolic Filling

Because the ventricles share a common septum, the filling of one may influence the compliance of the other, a phenomenon known as direct diastolic ventricular interaction (DVI). This interaction is markedly enhanced when the force exerted by the surrounding pericardium is raised (pericardial constraint). In health, in the resting state, we operate near the top of the flat component of a J-shaped pericardial stress–strain relation. Therefore, pericardial constraint (and hence DVI) is only minor. When right ventricular volume/pressure acutely increases, such as during exercise, massive pulmonary embolism, or right ventricular infarction, pericardial constraint increases and significant DVI develops. In this setting, the measured left ventricular intracavitary diastolic pressure markedly overestimates the true left ventricular filling pressure, because the external forces must be subtracted. Although the pericardium can grow during chronic cardiac enlargement, we present evidence that in certain chronic disease processes, including heart failure, DVI may also be important.     

Diastolic dysfunction

Opinion statement Heart failure is a leading cause of hospital admissions in North America. Approximately half of patients with symptoms of heart failure have normal or minimally impaired systolic function and are therefore diagnosed, by exclusion, with diastolic dysfunction. The therapy of diastolic dysfunction to date is largely unsatisfactory. There have been few outcome-based clinical trials to guide clinicians, and most treatments have been empirically derived from the data from systolic heart failure studies. In general, acute management consists of central volume reduction with loop diuretics and long-acting nitrates. In some cases improvement in left ventricular filling can be achieved by reducing heart rate, usually with either β blockers or calcium channel blockers. The role of digoxin is unclear and it should be used with caution. Theoretically, it has the capacity to further impair ventricular function, but one of the few trials in diastolic heart failure suggested that it improves symptoms and reduces hospitalization. Renin-angiotensin system blockade is a very attractive therapeutic avenue; angiotensin-converting enzyme inhibitors and angiotensin receptor blockers effectively reduce afterload, induce regression of left ventricular hypertrophy in excess of their blood pressure-lowering effect, and confer survival benefits to patients at high risk for cardiovascular death. Although the results of a recent trial using an angiotensin receptor blocker in patients with primarily diastolic heart failure were unimpressive, renin-angiotensin system blockade should still be considered because of its aforementioned benefits. The long-term management of these patients includes a careful assessment for and treatment of myocardial ischemia, treatment of hypertension, and reduction in left ventricular hypertrophy. For the treatment of ischemia, long-acting nitrates and calcium channel blockers may be particularly useful. The results of new trials in this area are expected soon, and hopefully therapy that directly targets the pathophysiologic pathways of this important disease is on the horizon.     

Effects of Eprosartan on Diastolic Function and Neurohormones in Patients with Hypertension and Diastolic Dysfunction

Objective  

To compare the effects of an angiotensin receptor blocker(ARB)-based regimen versus a non-ARB based regimen on diastolic function and neurohormones in patients with hypertension and diastolic dysfunction.     

Diastolic heart failure

Diastolic heart failure (DHF) is estimated to occur in 40% to 50% of patients with heart failure. Evidence suggests that DHF is primarily a cardiogeriatric syndrome that increases from approximately 1% at age 50 years to 10% or more at 80 years. DHF is also more likely to occur in older women who are hypertensive or diabetic. Although survival is better in patients with DHF compared with systolic heart failure, mortality rates for patients with DHF are four times higher than those for healthy, community-dwelling older adults. The increase in DHF is anticipated to continue during the next several decades largely because of the aging of the population; increase in risk factors associated with hypertension, diabetes, and obesity; and ongoing technologic advances in the treatment of cardiovascular disease. Few clinical trials have evaluated therapy in this population, so evidence about the effectiveness of treatment strategies for DHF is limited. Future research should target novel interventions that specifically target patients with DHF who are typically older and female, and experience exertional intolerance and have a considerably reduced quality of life.     

Diastolic filling dynamics in patients with aortic stenosis

Left ventricular filling dynamics were investigated in 24 patients with aortic stenosis (AS). Biplane cineangiography was performed with simultaneous micromanometry in these 24 patients and in six control subjects. Twelve of the patients with AS had moderate hypertrophy with a left ventricular muscle mass index of less than 180 g/m2 (ASI group) and 12 had severe hypertrophy with an index of 180 g/m2 or more (AS2 group). Filling dynamics were also evaluated postoperatively in eight patients in the AS1 and six patients in the AS2 group. Preoperatively, end-diastolic and end-systolic volume indexes were larger and ejection fraction was lower in the AS2 compared with the control or AS1 group. Percent volume increase during the first half of diastole (%V1) was smaller in the AS1 than in the AS2 group. Peak filling rate in the first half of diastole (PFR 1) was higher in the AS2 than in the control or in AS1 group, while peak filling rate in the second half of diastole (PFR2) was considerably greater in the AS1 group than in the other two groups. The time constant of left ventricular pressure decline, an index of the rate of relaxation, was prolonged in the AS2 group. In contrast, mitral valve opening pressure (MVOP) was significantly higher in this group than in the other two groups. The constant of left ventricular chamber stiffness was slightly but not significantly greater in both AS groups than in the control subjects. After surgery in patients in the AS1 group, preoperatively reduced %V1 had increased and preoperatively enhanced PFR2 had decreased. In patients in the AS2 group, excluding one with a persistent low ejection fraction after surgery, preoperatively enhanced PFR1 decreased in association with a decrease in MVOP. Thus, left ventricular filling dynamics vary in patients with AS depending on the degree of left ventricular hypertrophy and systolic function. In patients with AS and moderate hypertrophy %V1 is slightly reduced but is compensated for by a forceful atrial contraction. In those with severe hypertrophy and systolic dysfunction increased driving pressure allows %V1 to remain within normal limits, despite prolonged left ventricular relaxation and decreased elastic recoil. Both changes in left ventricular filling dynamics tend to normalize after surgery in association with a reduction in left ventricular hypertrophy and/or an improvement of systolic function.     

舒张性心功能不全

1992年,Braunwald把心力衰竭定义为“由于心收缩功能不正常,心脏不能泵出组织代谢所需要的相应血液,或仅能通过提高充盈后方能达到此目的的病理生理状态”。从而根据发病机制将以往的心力衰竭分成了“低心输出量”和“充盈压增高”两类。后来学者建议将二者进一步命名为收缩性心功能不全(systolic cardiac dysfunction,收缩性     

舒张功能不全心力衰竭研究的现状

约有50％充血性心力衰竭患者左室射血分数并未下降,这一亚群心力衰竭患者与左室射血分数下降心力衰竭患者存在许多明显的差异,目前已引起了相当的重视。现就其定义、诊断、流行病学调查情况、临床特点、治疗方法及预后等问题的现状作一简要的介绍。     

Diastolic dysfunction in patients with congenital heart disease

As noted in the introduction of this article, a comprehensive evaluation of diastolic function in all known congenital heart defects is not feasible; however, by demonstrating several representative anatomic and genetic abnormalities where diastolic dysfunction may have clinical significance, it is hoped that scaffolding has been established which will provide structure for further study on this intriguing and influential component of function in patients with CHD. Understanding the contribution of diastole to overall ventricular function may be shown to have important implications in the recommendations for timing or potential benefit of surgical intervention. Or, to state differently, if diastolic dysfunction precedes that of systolic, would a rigorous analysis of diastole in the presurgical patient provide a more sensitive algorithm for intervention? The means for noninvasive assessment of diastolic function, primarily by spectral Doppler echocardiography, or using echocardiography in conjunction with other modalities, should allow for a comprehensive accrual of data in this patient population.     

Diastolic Mitral Regurgitation

An 89-year-old female with a history of hypertension presented to the hospital with symptoms of fatigue. Her electrocardiogram (ECG) showed high-grade atrioventricular (AV) block, so a transthoracic echocardiogram was obtained to assess for structural heart abnormalities (Figure 1). Color Doppler showed mild mitral regurgitation (MR) extending into diastole. Temporal interrogation of the MR jet using continuous wave Doppler confirmed the diastolic component.Open in a separate windowFigure 1The hemodynamic elements of this mitral regurgitation (MR) are dissected and explained. MR: mitral regurgitation; LA: left atrial; LV: left ventricle; LVEDP: left ventricular end-diastolic pressure.Diastolic MR is generally described in the setting of AV dissociation. In patients with high-degree AV block and underlying sinus rhythm, the prolonged diastolic time with accompanying superimposed left atrial (LA) contractions will lead to a significant elevation in left ventricular end-diastolic pressure (LVEDP), creating a reverse gradient favoring flow from the left ventricle back into the LA during diastole. Diastolic MR also can occur with substantial elevations in LVEDP in restrictive cardiomyopathies and acute severe aortic regurgitation.     

Diastolic heart failure

Diastolic heart failure is a distinct clinical entity increasingly seen in older patients and requires special awareness to make the diagnosis. Although no single laboratory test is identified for making a confident diagnosis of diastolic dysfunction as the pathogenetic mechanism for heart failure, a constellation of echocardiographic and radionuclear findings are helpful in most cases. Invasive assessment of LV diastole is laborious, requiring high-fidelity pressures and accurate measures of volumes, and these are rarely needed to diagnose the condition. It appears that prognosis is significantly better for those with normal systolic function, when compared with congestive heart failure caused by impaired systolic pump function. Finally, the therapeutic approaches are substantially different for the two groups. It must be emphasized that even patients with predominant myocardial systolic dysfunction have some combined diastolic dysfunction as well. This latter group is difficult to treat. However, improvement in systolic pump function, when markedly impaired, must take precedence in management strategies.     

Diastolic mitral regurgitation in patients with hypertrophic cardiomyopathy

An analysis of the left ventricular angiograms of 31 patients with hypertrophic cardiomyopathy revealed diastolic mitral regurgitation in 4, a prevalence of 12.9%. The clinical, echocardiographic, angiographic, and hemodynamic data of these patients were reviewed. Diastolic mitral regurgitation could not be attributed to arrhythmia, PR interval prolongation, atrioventricular dissociation, aortic insufficiency, or aortic stenosis. Reduced left ventricular compliance was evidenced by elevated end-diastolic pressure following angiography and reduced diastolic E-F slope on echocardiography. It is speculated that the rapid inflow of blood into a poorly compliant ventricle established a turbulent flow pattern that resulted in the "floating" of blood back into the left atrium.     

Diastolic heart failure

Primary diastolic failure is typically seen in patients with hypertensive or valvular heart disease as well as in hypertrophic or restrictive cardiomyopathy but can also occur in a variety of clinical disorders, especially tachycardia and ischemia. Diastolic dysfunction has a particularly high prevalence in elderly patients and is generally associated, with low mortality but high morbidity. The pathophysiology of diastolic dysfunction includes delayed relaxation, impaired LV filling and/or increased stiffness. These conditions result typically in an upward displacement of the diastolic pressure-volume relationship with increased end-diastolic, left atrial and pulmo-capillary wedge pressure leading to symptoms of pulmonary congestion. Diagnosis of diastolic heart failure requires three conditions: (1) presence of signs or symptoms of heart failure; (2) presence of normal or slightly reduced LV ejection fraction (EF > 50%) and (3) presence of increased diastolic filling pressure. Assessment of diastolic function can be performed with several non-invasive (2D- and Doppler-echocardiography, color Doppler M-mode, Doppler tissue imaging, MR-myocardial tagging, radionuclide ventriculography) and invasive techniques (micromanometry, angiography, conductance method). Doppler-echocardiography is the most useful tool to routinely measure diastolic function. Different techniques can be used alone or in combination to assess LV diastolic function, but most of them are dependent on heart rate, pre- and afterload. The transmitral flow pattern remains the starting point, since it is easy to acquire and rapidly categorizes patients into normal (E > A), delayed relaxation (E < A), and restrictive (E > A) filling patterns. Invasive assessment of diastolic function allows determination of the time constant of relaxation from the exponential pressure decay during isovolumic relaxation, and the evaluation of the passive elastic properties from the slope of the diastolic pressure-volume (= constant of chamber stiffness) and stress-strain relationship (= constant of myocardial stiffness). The prognosis of diastolic heart failure is usually better than for systolic dysfunction. Diastolic heart failure is associated with a lower annual mortality rate of approximately 8% as compared to annual mortality of 19% in heart failure with systolic dysfunction, however, morbidity rate can be substantial. Thus, diastolic heart failure is an important clinical disorder mainly seen in the elderly patients with hypertensive heart disease. Early recognition and appropriate therapy of diastolic dysfunction is advisable to prevent further progression to diastolic heart failure and death. There is no specific therapy to improve LV diastolic function directly. Medical therapy of diastolic dysfunction is often empirical and lacks clear-cut pathophysiologic concepts. Nevertheless, there is growing evidence that calcium channel blockers, beta-blockers, ACE-inhibitors and AT2-blockers as well as nitric oxide donors can be beneficial. Treatment of the underlying disease is currently the most important therapeutic approach.     

Diastolic heart failure

Opinion statement