The rate of change of left ventricular volume in man. II. Diastolic events in health and disease

Exercise physiology of the left atrium: quantity and timing of contribution to cardiac output

Although the phases of left atrial (LA) function at rest have been studied, the physiological response of the LA to exercise is undefined. This study defines the exercise behavior of the normal left atrium by quantitating its volumetric response to graded effort. Healthy subjects (n = 131) were enrolled from the Health eHeart cohort. Echocardiograms were obtained at baseline and during ramped supine bicycle exercise. Left ventricular volume index, stroke volume index (LVSVI), left atrial end-systolic volume index (LAESVI), left atrial end-diastolic volume index (LAEDVI), and left atrial emptying fraction (LAEF), reservoir fraction, and conduit fraction were analyzed. The LVSVI increased with low exercise but did not increase further with peak exercise; cardiac output increased through the agency of heart rate. The LAESVI and LAEDVI decreased and the LAEF increased with exercise. As a result, the LA reservoir volume index was static throughout exercise. The reservoir fraction decreased from 46% at rest to 40% with low exercise (P < 0.001) in association with increased LVSVI and remained similar at peak exercise. The conduit volume index increased from 20 mL/m² at rest to 24 mL/m² at low exercise and stayed the same at peak exercise. Similarly, the conduit fraction increased from 54% at rest to 60% at low exercise (P < 0.001) and did not change further with peak exercise. Although atrial function increased with exercise, the major contribution to the augmentation of LV stroke volume is LA conduit fraction, a marker of active ventricular relaxation. Furthermore, the major determinant of raising cardiac output during high-level exercise is heart rate.NEW & NOTEWORTHY Diseases of the left atrium (LA) are major sources of disability (e.g., strokes and fatigue), but its exercise physiology has been unstudied. Such knowledge may allow early recognition of disease and suggest therapies. We show that in normal subjects, low-level exercise decreases LA volume and increases its ejection fraction. However, these changes offset each other volumetrically, and the contribution to LV filling from a full to an empty LA (reservoir function) is static. Higher levels of exercise do not change LA reservoir contribution. Blood flowing directly from the pulmonary vein to LV (conduit flow) impelled by augmented LV active relaxation (suction) is the major source of a modest increase in LV stroke volume. The major source of increased cardiac output with exercise is heart rate. During all stages of exercise, the LA works hard but only to keep up. We believe that our findings provide an additional set of benchmarks through which to quantitate LA pathology and gauge its progression.

Numerical Study of Atrial Fibrillation Effects on Flow Distribution in Aortic Circulation

Atrial fibrillation (AF) is the most common type of arrhythmia, which undermines cardiac function. Atrial fibrillation is a multi-facet malady and it may occur as a result of other diseases or it may trigger other problems. One of the main complications of AF is stroke due to the possibility of clot formation inside the atrium. However, the possibility of stroke occurrence due to the AF and the location from which an embolus dispatches are subject of debate. Another hypothesis about the embolus formation during AF is thrombus formation in aorta and carotid arteries, embolus detachment and its movement. To investigate the possibility of the latter postulation, the current work suggests a parametric study to quantify the sensitivity of aortic flow to four common AF traits including lack of atrial kick, atrial remodelling, left ventricle systolic dysfunction, and high frequency fibrillation. The simulation was carried out by coupling several in-house codes and ANSYS-CFX module. The results reveal that AF traits lower flow rate at left ventricular outflow tract, which in general lowers blood perfusion to systemic, cerebral and coronary circulations. Consequently, it leads to endothelial cell activation potential (ECAP) increase and variation of flow structure that both suggest predisposed areas to atherogenesis and thrombus formation in different regions in ascending aorta, aortic arch and descending thoracic aorta.

Impaired left ventricular diastolic function in T2DM patients is closely related to glycemic control

BACKGROUND

Left ventricular (LV) diastolic dysfunction commonly is observed in individuals with type 2 diabetes mellitus (T2DM). We employed transthoracic echocardiography (TTE) and cardiac magnetic resonance imaging (CMRI) to investigate the hypothesis that LV diastolic dysfunction in T2DM is associated with poor glycemic control.

METHODS

Forty subjects, 21 with normal glucose tolerance (NGT) and 19 with T2DM, were studied with CMRI and TTE to assess LV function. Early-to-late transmitral flow ratio (E/A) and deceleration time (DecT) were assessed with both modalities. Normalized (to body surface area) end-diastolic volume (EDV/BSA) and normalized peak LV filling rate (pLVFR/BSA) were assessed with CMRI. Early transmitral flow velocity to septal velocity (E/e') and isovolumetric relaxation time (IVRT) were measured using TTE. Dimensional parameters were normalized to body surface area (BSA).

RESULTS

CMRI measurements demonstrated impaired E/A (1.13 ± 0.34 vs 1.62 ± 0.42, P < .001), increased DecT (174 ± 46 ms vs 146 ± 15, P = .005), as well as lower EDV/BSA (63 ± 10 vs 72 ± 9 mL/m2, P < .01) and pLVFR/BSA (189 ± 46 vs 221 ± 48 mL s-1 m-2, P < .05) in T2DM subjects. TTE measurements revealed lower E/A (1.1 ± 0.4 vs 1.4 ± 0.2, P < .001) and E/e' (6.8 ± 1.5 vs 8.7 ± 2.0, P < .0001) with higher DecT (203 ± 22 ms vs 179 ± 18, P < .001) and IVRT (106 ± 14 ms vs 92 ± 10, P < .001) in T2DM. Multiple parameters of LV function: E/ACMRI (r = -.50, P = .001), E/ATTE (r = -.46, P < .005), pLVFR/BSA (r = -.35, P < .05), E/e' (r = -.46, P < .005), EDV/BSACMRI (r = -.51, P < .0001), EDV/BSATTE (r = -.42, P < .01) were negatively correlated with HbA1c. All but E/e' also were inversely correlated with fasting plasma glucose (FPG).

CONCLUSIONS

Impaired LV diastolic function (DF) was found in T2DM subjects with both CMRI and TTE, and multiple LVDF parameters correlated negatively with HbA1c and FPG. These results indicate that impaired LVDF is inversely linked to glycemic control in T2DM patients.

Non-invasive measurement of volume-time curves in patients with mitral regurgitation and in healthy volunteers, using a new operator-independent screening tool

Left ventricular volume-time curves (VTCs) provide hemodynamic data, and may help clinical decision making. The generation of VTCs using echocardiography, however, is time-consuming and prone to inter-operator variability. In this study, we used a new non-invasive, operator-independent technique, the hemodynamic cardiac profiler (HCP), to generate VTCs. The HCP, which uses a low-intensity, patient-safe, high-frequency applied AC current, and 12 standard ECG electrodes attached on the thorax in a pre-defined pattern, was applied to five young healthy volunteers, five older healthy volunteers, and five patients with severe mitral regurgitation. From the VTCs generated by the HCP, the presence or absence of an isovolumetric contraction phase (ICP) was assessed, as well as the left ventricular ejection time (LVET), time of the pre-ejection period (tPEP), and ratio of the volumes of the early (E) and late (A) diastolic filling (E _V/A _V ratio), and compared to 2D transthoracic echocardiography (2D TTE) at rest. The reproducibility by two different operators showed good results (RMS  =  5.2%). For intra-patient measurement RMS was 2.8%. Both LVET and the E _V/A _V ratio showed a strong significant correlation between HCP and 2D TTE derived parameters (p  <  0.05). For tPEP, the correlation was still weak (p  =  0.32). In all five patients with mitral regurgitation, the ICP was absent in the VTC from the HCP, whereas it was present in the 10 healthy volunteers, which is in accordance with pathophysiology. We conclude that the HCP seems to be a method for reproducible VTC generation, and may become a useful early screening tool for cardiac dysfunction in the future.

Influence of valve size, orientation and downstream geometry of an aortic BMHV on leaflet motion and clinically used valve performance parameters

The aim of this study was to reconcile some of our own previous work and the work of others to generate a physiologically realistic numerical simulation environment that allows to virtually assess the performance of BMHVs. The model incorporates: (i) a left ventricular deformable model to generate a physiological inflow to the aortic valve; (ii) a patient-specific aortic geometry (root, arch and descending aorta); (iii) physiological pressure and flow boundary conditions. We particularly studied the influence of downstream geometry, valve size and orientation on leaflet kinematics and functional indices used in clinical routine. Compared to the straight tube geometry, the patient-specific aorta leads to a significant asynchronous movement of the valve, especially during the closing of the valve. The anterior leaflet starts to close first, impacts the casing at the closed position and remains in this position. At the same time, the posterior leaflet impacts the pivoting mechanisms at the fully open position. At the end of systole, this leaflet subsequently accelerates to the closed position, impacting the casing with an angular velocity of approximately -477 rad/s. The valve size greatly influences the transvalvular pressure gradient (TPG), but does not change the overall leaflet kinematics. This is in contrast to changes in valve orientation, where changing valve orientation induces large differences in leaflet kinematics, but the TPG remains approximately the same.

Is Peri-Operative Isolated Systolic Hypertension (ISH) a Cardiac Risk Factor?

We are presenting a review of Isolated Systolic Hypertension (ISH) as a cardiovascular risk factor with emphasis on the perioperative period.

Isolated systolic hypertension is associated with aging and is the most frequent subtype (65%) among patients with uncontrolled hypertension. ISH is strongly associated with increased risks of cardiac and cerebrovascular events exceeding those in comparably aged individuals with diastolic hypertension. Patients with ISH show an increase in left ventricular (LV) mass and an increase in the prevalence of left ventricular hypertrophy (LVH). These LV changes increase cardiovascular events and frequently lead to diastolic dysfunction (DD). Treatment to reduce elevated systolic blood pressure has been shown to reduce the risk of cardiovascular events.

In the perioperative setting, essential hypertension has not been found to be a significant risk factor for cardiac complications. Most of the studies were based on the definition of essential hypertension and underpowered in sample size. The significance of perioperative ISH, however, is not well studied, partly due to its recognition only fairly recently as a cardiovascular risk factor in the non-surgical setting, and partly due to the evolving definition of ISH.

Perioperative cardiac complications remain a significant problem to the healthcare system and to the patient. Although the incidence of perioperative cardiac complications is prominent in high-risk patients as defined by the Revised Cardiac Risk Index (RCRI), the bulk of the cardiac complications actually occur in low-risk group. Currently, little understanding exists on the occurrence of perioperative cardiac complications in low- risk patients. A factor such as ISH, with its known pathophysiological changes, is a potential perioperative risk factor.

We believe ISH is an under-recognized perioperative risk factor and deserves further studying. Our research group has recently been funded by the Heart Stroke Foundation (HSF) to examine ISH as a perioperative risk factor (PROMISE Study).

Note: Human heartbeat measurement on the basis of current generated by electrostatic induction

In this study, we developed an effective nonattached, noncontact technique for measurement of the human heartbeat. This method detects the human heartbeat by measuring the current generated by variations in the capacitance between a given electrode and the human body. An electrode is placed a few centimeters from the subject's chest, and the electrostatic induction current (on the order of picoamperes) flowing through the electrode is then detected. We propose an occurrence model for the electrostatic induction current generated by variations in the electrostatic capacitance generated because of the human heartbeat, with respect to a given measurement electrode. Furthermore, we compared waveforms of the human heartbeat simultaneously obtained by using conventional electrocardiography (ECG) and our proposed electrostatic induction method. The waveform obtained using the proposed method had the same cycle as that obtained using conventional ECG. This confirms that we can detect the human heartbeat under nonattached, noncontact conditions.

High temporal resolution SSFP cine MRI for estimation of left ventricular diastolic parameters

PURPOSE

To obtain high temporal resolution (HTR) magnetic resonance (MR) steady-state free-precession (SSFP) cine cardiac images by using multichannel radiofrequency (RF) hardware and parallel imaging techniques; to study the effect of temporal resolution; and to compare the derived left ventricular (LV) diastolic filling parameters with echocardiographic results.

MATERIALS AND METHODS

HTR images were acquired in 13 healthy volunteers using a 1.5 T scanner with 32 RF channels and sensitivity encoding (SENSE) and k-t broad-use linear-acquisition speedup technique (k-t BLAST) imaging techniques. LV diastolic parameters were calculated and compared to conventional echocardiographic indices such as the isovolumic relaxation time (IVRT) and E/A ratio. The need for HTR was assessed and the MR results were compared with echocardiographic results.

RESULTS

The HTR (approximately 6-ms) images yielded higher peak filling rates, peak ejection rates, and peak atrial filling rates. A progressive decline in filling and ejection rates was observed with worsening temporal resolution. The IVRTs and E/A ratios measured with MR versus echocardiography were in broad agreement. Also, SENSE and k-t BLAST yielded similar diastolic functional parameters.

CONCLUSION

With SENSE or k-t BLAST and modern hardware, HTR cine images can be obtained. The lower temporal resolutions (30-50 ms) used in clinical practice reduce LV filling rates by <or=30% and may hinder characterization of transient phenomena such as the IVRT.

Impact of diastolic dysfunction severity on global left ventricular volumetric filling - assessment by automated segmentation of routine cine cardiovascular magnetic resonance

OBJECTIVES

To examine relationships between severity of echocardiography (echo) -evidenced diastolic dysfunction (DD) and volumetric filling by automated processing of routine cine cardiovascular magnetic resonance (CMR).

BACKGROUND

Cine-CMR provides high-resolution assessment of left ventricular (LV) chamber volumes. Automated segmentation (LV-METRIC) yields LV filling curves by segmenting all short-axis images across all temporal phases. This study used cine-CMR to assess filling changes that occur with progressive DD.

METHODS

115 post-MI patients underwent CMR and echo within 1 day. LV-METRIC yielded multiple diastolic indices - E:A ratio, peak filling rate (PFR), time to peak filling rate (TPFR), and diastolic volume recovery (DVR80 - proportion of diastole required to recover 80% stroke volume). Echo was the reference for DD.

RESULTS

LV-METRIC successfully generated LV filling curves in all patients. CMR indices were reproducible (< or = 1% inter-reader differences) and required minimal processing time (175 +/- 34 images/exam, 2:09 +/- 0:51 minutes). CMR E:A ratio decreased with grade 1 and increased with grades 2-3 DD. Diastolic filling intervals, measured by DVR80 or TPFR, prolonged with grade 1 and shortened with grade 3 DD, paralleling echo deceleration time (p < 0.001). PFR by CMR increased with DD grade, similar to E/e' (p < 0.001). Prolonged DVR80 identified 71% of patients with echo-evidenced grade 1 but no patients with grade 3 DD, and stroke-volume adjusted PFR identified 67% with grade 3 but none with grade 1 DD (matched specificity = 83%). The combination of DVR80 and PFR identified 53% of patients with grade 2 DD. Prolonged DVR80 was associated with grade 1 (OR 2.79, CI 1.65-4.05, p = 0.001) with a similar trend for grade 2 (OR 1.35, CI 0.98-1.74, p = 0.06), whereas high PFR was associated with grade 3 (OR 1.14, CI 1.02-1.25, p = 0.02) DD.

CONCLUSIONS

Automated cine-CMR segmentation can discern LV filling changes that occur with increasing severity of echo-evidenced DD. Impaired relaxation is associated with prolonged filling intervals whereas restrictive filling is characterized by increased filling rates.

Effect of reduced total blood volume on left ventricular volumes and kinetics in type 2 diabetes

AIM

Although impaired left ventricular (LV) diastolic function is commonly observed in patients with type 2 diabetes, it remains unclear whether the impairment is caused by altered LV relaxation or changes in LV preload. The purpose of this study was to examine the influence of LV function and LV loading conditions on stroke volume in men with type 2 diabetes.

METHODS

Cardiac magnetic resonance imaging scans were performed in eight men with type 2 diabetes and 11 non-diabetic men matched for age, weight and physical activity level. Total blood volume was determined with the Evans blue dye dilution technique.

RESULTS

End-diastolic volume (EDV), the ratio of peak early to late mitral inflow velocity (E/A) and stroke volume were lower in men with type 2 diabetes than in non-diabetic individuals. Peak filling rate and peak ejection rate were not different between diabetic and non-diabetic individuals; however, men with type 2 diabetes had proportionally longer systolic duration than non-diabetic individuals. Heart rate was higher and total blood volume was lower in men with type 2 diabetes. The lower total blood volume was correlated with a lower EDV in men with type 2 diabetes.

CONCLUSIONS

Men with type 2 diabetes have an altered cardiac cycle and lower end-diastolic and stroke volume. A lower total blood volume and higher heart rate in men with type 2 diabetes suggest that changes in LV preload, independent of changes in LV relaxation or contractility, influence LV diastolic filling and stroke volume in this population.

Diastolic dysfunction: a link between hypertension and heart failure

Diastolic heart failure is characterized by the symptoms and signs of heart failure, a preserved ejection fraction and abnormal left ventricular (LV) diastolic function caused by a decreased LV compliance and relaxation. The signs and symptoms of diastolic heart failure are indistinguishable from those of heart failure related to systolic dysfunction; therefore, the diagnosis of diastolic heart failure is often one of exclusion. The majority of patients with heart failure and preserved ejection fraction have a history of hypertension. Hypertension induces a compensatory thickening of the ventricular wall in an attempt to normalize wall stress, which results in LV concentric hypertrophy, which in turn decreases LV compliance and LV diastolic filling. There is an abnormal accumulation of fibrillar collagen accompanying the hypertension-induced LV hypertrophy, which is also associated with decreased compliance and LV diastolic dysfunction. There are no specific guidelines for treating diastolic heart failure, but pharmacological treatment should be directed at normalizing blood pressure, promoting regression of LV hypertrophy, preventing tachycardia and treating symptoms of congestion. Preventive strategies directed toward an early and aggressive blood pressure control are likely to offer the greatest promise for reducing the incidence of diastolic heart failure.

Dual-source CT with improved temporal resolution in assessment of left ventricular function: a pilot study

OBJECTIVE

Functional analysis using MDCT has been limited by insufficient temporal resolution. The aim of this study was to assess the performance of a dual-source CT system with improved temporal resolution in the determination of both volume- or time-dependent functional parameters and regional wall motion in comparison with cine MRI.

SUBJECTS AND METHODS

Twenty patients (15 of whom had previous myocardial infarction) were prospectively examined using dual-source CT. MRI was used as the standard of reference. Using the Simpson's method, ventricular volumes were determined for the whole of the cardiac cycle and results compared using Parson's correlation and Bland-Altman analysis. Regional wall motion was assessed on cine images and compared using weighted kappa statistics.

RESULTS

Dual-source CT revealed a strong correlation with cine MRI regarding the quantification of end-diastolic volume (r = 0.98), end-systolic volume (r = 0.99), stroke volume (r = 0.96), and ejection fraction (r = 0.95). Good correlation was obtained for peak ejection rate (r = 0.79) and peak filling rate (r = 0.84), whereas agreement proved only moderate for time-to-peak ejection rate (r = 0.68) or time-to-peak filling rate from end-systole (r = 0.64). The mean difference for ejection fraction was negligible (bias, 0.72%). Good agreement between both techniques was likewise found for regional wall motion (kappa = 0.88).

CONCLUSION

With the improvement of temporal resolution between 42 and 83 milliseconds, dual-source CT not only enables accurate assessment of global functional parameters, but it also allows for quantification of time-dependent variables and reliable evaluation of regional wall motion.

Frequency and determinants of early rapid filling abnormality

BACKGROUND

The frequency and determinants of early rapid diastolic filling abnormalities in the community and in cardiac patients are poorly understood.

METHODS AND RESULTS

Early left ventricular (LV) rapid filling was assessed via equilibrium radionuclide angiocardiography in 70 community volunteers (LV ejection fraction [EF] > or = 0.50) and 778 cardiac patients, all aged at least 45 years. The frequency of early rapid filling and the independent clinical, therapeutic, and hemodynamic variables predictive of early rapid filling abnormality were determined. Depending on the parameter assessed, early rapid filling was abnormal in 27% to 54% of the community volunteers, 34% to 53% of cardiac patients with an LVEF of 0.50 or greater, and 42% to 67% of cardiac patients with an LVEF lower than 0.50. On the basis of multivariate analysis, models of clinical, therapeutic, and hemodynamic variables were modestly predictive of early rapid filling abnormality. Age, sex, valvular insufficiency, hypertension, digoxin use, and heart rate were independent determinants of early rapid filling.

CONCLUSIONS

In participants aged older than 44 years, early rapid filling was frequently abnormal in the community volunteers and in patients with an LVEF of 0.50 or greater and was most common in patients with an LVEF lower than 0.50. Clinical, therapeutic, and hemodynamic variables had modest independent predictive value for early rapid filling abnormality.

Analysis of global systolic and diastolic left ventricular performance using volume-time curves by real-time three-dimensional echocardiography

BACKGROUND

Left ventricular (LV) volume-time curves (VTC) have been described to provide quantitative data on the dynamics of global LV performance beyond ejection fraction. However, generation of VTCs by conventional 2-dimensional imaging techniques is inherently limited because of inaccurate geometric volume assumptions. We, therefore, studied whether the new concept of volumetric scanning as realized by real-time 3-dimensional echocardiography (RT-3DE) can be used to provide accurate VTCs.

METHODS

In 30 healthy participants, VTCs were generated from 18 to 24 absolute LV volumes per second by transthoracic RT-3DE and compared with magnetic resonance imaging (MRI) used for reference. LVs were traced manually in 9 to 11 parallel, short-axis planes and volumes calculated by disk method. From VTCs, we determined peak ejection rate (PER), peak early filling rate (PFR), time to PER and PFR, and end-diastolic and end-systolic volumes. For initial clinical application, 2 patient groups of coronary (n = 15) and hypertensive heart disease (n = 16) were studied.

RESULTS

In healthy participants, VTCs agreed with MRI (mean errors: PER, -39 +/- 67 mL/s; PFR, -18 +/- 84 mL/s; time to PER, 8 +/- 21 milliseconds; time to PFR 4 +/- 18 milliseconds [not significant vs 0]) whereas VTCs in coronary and hypertensive groups revealed significantly impaired diastolic function. Scanning time for VTCs was only 1 to 2 minutes by RT-3DE and 8 +/- 2 minutes by MRI (P <.001) and time for offline analysis was 22 +/- 5 minutes versus 24 +/- 4 minutes by MRI (not significant).

CONCLUSIONS

Generation of VTCs by RT-3DE is feasible and shows excellent agreement with MRI used for reference. Thus, VTCs by RT-3DE is a promising new approach providing access to quantitative information on global LV performance such as LV filling rates that is currently unavailable for the cardiologist.

Use of electron beam tomography to quantify cardiac diastolic function

The examples provided in this article indicate that EBT, in addition to allowing for detailed descriptions of cardiac anatomy and contraction characteristics in man, can also be used to evaluate global and regional LV diastolic function using an approach previously validated for applications in radionuclide angiography. EBT is an established imaging modality that has been shown to be highly applicable to quantitative determination of ventricular mass, RV and LV volumes, and global and regional ventricular systolic and diastolic function in a variety of cardiac pathologic states. The attractiveness of EBT lies not so much in a single determination of systolic function or diastolic filling in a given individual, but in the strength of an easily acquired, highly reproducible, and accurate serial imaging method in patients following pharmacologic or interventional therapy for a specific cardiac disease.

The echo-Doppler evaluation of left ventricular diastolic function. A current perspective

The role of left ventricular (LV) diastolic function in health and disease is still incompletely understood and under appreciated by most primary care physicians and many cardiologists. Physical examination, electrocardiogram, and chest radiographs are unreliable in making the diagnosis of LV diastolic dysfunction in most individuals, and invasive measurements of cardiac pressures, rates of LV relaxation, and LV compliance are costly, clinically impracticable as they carry increased risk, and require special catheters and software analysis programs. The authors address the definition of LV diastolic dysfunction, history of diastole, LV filling patterns, pulmonary venous flow velocity variables, additional ancillary data, practical echo-Doppler evaluation of LV diastolic function, and limitations.

Unsolved problems in diastole

It is now recognized that a sizable portion of patients who exhibit symptoms of congestive heart failure have relatively well-preserved systolic function, but have significantly elevated LV filling pressures. This syndrome, termed "diastolic heart failure," is associated with various conditions such as aging, anatomic abnormalities, hypertension, ischemic disease, tachycardia, and atrial fibrillation. Advances in the proper medical and surgical management of these patients will depend on the continued delineation of the basic physiologic mechanisms that account for normal and pathologic cardiac diastolic function. This goal can only be achieved by the integration of information acquired from basic science investigations conducted in vitro and in vivo, mathematic modeling simulation studies, and prospective, community-based investigations that characterize the incidence, prevalence, and natural history of the disease. In addition, randomized clinical trials will be needed to determine the optimal treatment strategies for this group of patients--strategy choices undoubtably complicated by a disease whose treatment is influenced to a large extent by its origin. The future therapies evaluated in these randomized clinical trials will most likely range from medical therapies that target either the heart directly or the peripheral vascular system, to surgical interventions such as direct myocardial revascularization, to gene therapy. Finally, it is worth mentioning one more unresolved issue that is of general practical concern not only to the physiologist studying diastolic function, but also to the clinician: whether or not it is even feasible to develop a single, sensitive, specific, clinically relevant index of diastolic function that is free from the contaminating influences of rate, contractility, and load. As observed by Glantz 20 years ago, developing indexes with the hope that one might fully delineate the left ventricle's diastolic properties, rather than concentrating on discovering the physiologic significance of such indexes, is probably counterproductive. More recently, in a related article, Slinker implied that an operational definition of any aspect of cardiac function must allow for the measurement of that function over an adequate range of essential variables. Therefore, as previously mentioned, the physiologist studying cardiac function has the daunting task of trying to understand, in a precise way, how the processes and mechanisms of the various phases of the cardiac cycle couple together to produce either a normal or abnormal functioning heart. It seems clear that because of the complex weave of factors that control overall cardiac diastolic function, the derivation of any single index that adequately describes LV diastolic function in vivo may not be possible.

Right ventricular diastolic function in patients with hypertrophic cardiomyopathy--an invasive study

To assess diastolic function of the right ventricle (RV) in patients with hypertrophic cardiomyopathy (HCM), biplane RV angiograms and RV pressures were analyzed in 19 HCM patients and in 13 normal subjects. RV and left ventricle (LV) pressures were measured using catheter-tip manometers. RV volumes were obtained from frame-by-frame tracings of angiograms. Ventricular relaxation was assessed by the time constant of isovolumic pressure decay (T). The peak filling rate (PFR) and the time to PFR (TPFR) were used as parameters of early diastolic filling, and the right atrial contribution to RV filling (%AF) was used as a parameter of late diastolic filling. The T for the RV was significantly prolonged in HCM patients. However, there was no significant correlation between the T for the RV and LV, nor did the T for the RV correlate with the RV ejection fraction or interventricular septal wall thickness. The TPFR, but not PFR, was significantly greater in HCM patients, and the %AF tended to be increased in HCM, but not significantly. The RV diastolic pressure-volume relations in the HCM patients shifted upward. In conclusion, impaired isovolumic relaxation and delayed diastolic filling and decreased diastolic distensibility are present in the RV of HCM patients.

Cardiac mechanical energy and effects on the arterial tree

Blood flow pulsatility is the result of the heart's activity as a pump unable to develop steady flow, and its interaction with the arterial tree. Thus, the heart is a cyclic energy generator whose adequate function requires the two phases of this cycle to be normal. Diastolic properties determine the degree of filling of the ventricles and the strength of the following systole. Systole, in turn, must generate enough energy to overcome forces opposing ejection. These can be divided into internal (the mechanical characteristics of the ventricle itself) and external loads (the characteristics of the arterial tree). As a result, hydraulic energy is imparted to blood (external ventricular work) that manifests itself as blood pressure and flow. Given the cyclic nature of cardiac activity, the external ventricular work has steady and pulsatile components. The steady component is energy lost during steady flow because of vascular resistance, and the pulsatile work is that lost in arterial pulsations and mainly depends on the aortic impedance. Thus, the characteristics of the arterial tree will determine the relative contribution of these two components to blood flow and the efficency of the heart. In addition, the arterial tree modifies the different waves (pressure and flow) traveling in the circulation. These modifications have important consequences for cardiac function. The ventricle and the arterial tree constitute a coupled biological system, and its overall performance is a function of the behavior of each unit at any given moment.

Effects of cardiac output on Doppler transmitral and transtricuspid flow velocity patterns in very low birth weight infants

We studied effects of cardiac output on Doppler transmitral and transtricuspid flow velocities in 24 appropriate for gestational age premature infants. We measured peak flow velocity of early diastole (peak E) and atrial contraction (peak A), ratio of peak flow velocity of early diastole to atrial contraction (peak E/A), total flow velocity-time integral, the first third filling fraction, peak filling rate normalized to stroke volume, and deceleration time (DT). Cardiac output was calculated as the product of the aortic flow velocity-time integral, aortic valve area, and heart rate. The cardiac output increased significantly with advancing gestational age and body weight (r = 0.78 and 0.86, P < 0.01, respectively). With increasing cardiac output, the transmitral as well as transtricuspid peak E, peak E/A, and total flow velocity-time integral increased significantly without any change in the peak filling rate normalized to stroke volume, peak A, and deceleration time. The transmitral as well as transtricuspid peak E did not correlate with the heart rate. Although these results do not establish whether changes in ventricular relaxation process or in cardiac output is responsible for the progressive increase in the peak E and peak E/A. Unchanged peak filling rate normalized to stroke volume of the left and right ventricles suggest that changes in cardiac output with maturity is, in fact, one of the important contributory factors. This evidence should be borne in mind in interpreting ventricular diastolic filling as an index of ventricular diastolic function in premature infants.

Canadian consensus recommendations for the measurement and reporting of diastolic dysfunction by echocardiography: from the Investigators of Consensus on Diastolic Dysfunction by Echocardiography

Abnormalities of diastolic filling are increasingly recognized as a cause of symptoms and predictors of outcome in patients with most forms of heart disease. Noninvasive assessment of diastolic filling is possible in almost all patients, but accurate evaluation must relate echocardiographic Doppler measurements to the complex physiologic and hemodynamic factors responsible for normal and abnormal filling. This evaluation has been facilitated by recent correlation of Doppler measurement of mitral and pulmonary venous inflow with hemodynamic studies. These studies have confirmed that when a careful, integrated approach is taken, Doppler flow patterns can document a progressive pattern of abnormality in many conditions. Impaired left ventricular (LV) relaxation is seen early and is recognized by a decrease in early transmitral LV filling and an increased proportion of filling during atrial contraction. As abnormalities progress, increasing LV chamber stiffness and elevated left atrial pressure lead to a "pseudonormal" filling pattern that previously has caused considerable confusion. This can be unmasked by careful evaluation of pulmonary venous inflow and the use of the Valsalva maneuver. When marked diastolic abnormalities are present, LV filling has restrictive features characterized by rapid early filling, a very stiff left ventricle with high filling pressures, and a poor prognosis. Routine measurement of indexes of diastolic filling have been hampered by uncertainty as to what should be measured, what techniques should be used, definition of normal values, and a clear method of reporting findings. This report represents the efforts of a Canadian consensus group to define a national standard for the performance and reporting of echocardiographic Doppler studies of diastolic filling.

Assessment of posterior aortic wall motion using echocardiogram in patients with atrial fibrillation

BACKGROUND AND HYPOTHESIS

Noninvasive evaluation of left ventricular (LV) diastolic function was performed on 12 patients with atrial fibrillation (AF) using posterior aortic wall echocardiogram and a parameter for determining the optimal heart rate in patients with chronic atrial fibrillation was considered.

METHODS

Subjects were divided into two groups; one with no underlying cardiac disease (AF only group; n = 7) and the other with dilated cardiomyopathy (DCM group; n = 5). Left atrial emptying index (LAEI) obtained from the posterior aortic wall echocardiogram was used as the parameter of LV diastolic function, and R-R interval-LAEI relation and minimum R-R interval showing LAEI = 1.0 were investigated and compared between the two groups.

RESULTS

There was a good correlation between R-R interval and LAEI until LAEI of 1.0 was obtained in all patients. Slope of the regression line was significantly steeper in the AF only group than in the DCM group, and minimum R-R interval showing LAEI = 1.0 was significantly shorter in the AF only group.

CONCLUSION

Assessment of R-R interval-LAEI relation was useful for the noninvasive evaluation of LV diastolic function, and this parameter could be used for clinical application to determine the optimal heart rate in atrial fibrillation.

The assessment of left ventricular filling dynamics using an online automatic border detection algorithm: comparison with cineventriculography

An echocardiographic system has been developed that performs automatic endocardial border detection and instantaneously calculates and displays a waveform of left ventricular cavity area versus time. The purpose of this study was to compare measurements of left ventricular filling dynamics from automatic border detection echocardiography with similar measurements from cineventriculography. Thirty-three patients undergoing cardiac catheterization had automatic border detection echocardiography performed within 45 minutes of cineventriculography. Ten patients had normal catheterization findings and 23 had cardiac disease. The automatic border detection waveforms generated from two echocardiographic views were measured to determine the fraction of filling occurring during the early diastolic rapid filling phase and during the filling phase resulting from atrial contraction. Similar fractions were derived from curves generated from frame-by-frame measurements of cineangiographic volumes. Results were analyzed by correlating echocardiographic and cineventriculographic results, and by a limits of agreement analysis (limits of agreement were +/- 2 standard deviations of the mean difference between echocardiography and cineventriculography). There were significant correlations between echocardiography and cineventriculography for each of the parameters studied. The best results were obtained for the apical four-chamber view (rapid filling fraction r = 0.72, P < 0.0001, atrial filling fraction r = 0.56, P < 0.001). Differences in filling patterns between normal and abnormal patient groups detected by cineventriculography were also detected by automatic border detection echocardiography. However, broad limits of agreement were observed, that may limit the ability of the automatic border detection system to reliably predict cineventriculographic results in an individual patient. Automatic border detection echocardiography can provide information about left ventricular filling dynamics that is similar to that obtained from frame-by-frame analysis of cineventriculograms. However, the variability in the results may limit the application of the technique in individual patients.

Heart failure with normal systolic function: a common disorder in older people

OBJECTIVE

To review the incidence, pathophysiology, significance, diagnosis, and treatment of heart failure with normal systolic function in older patients.

DATA SOURCE

Scientific reports of diastolic ventricular dysfunction in both the general population and the geriatric population were identified from repeated searches of the MEDLINE database and citations from appropriate articles.

STUDY SELECTION

Studies were included only if they demonstrated proper methodology, were from a reputable source, and were published in a peer-reviewed journal.

DATA EXTRACTION AND SYNTHESIS

Relevant data were obtained from the articles, with special importance placed on studies designed to examine older patients exclusively or as part of a subgroup in a larger study. Emphasis was placed on data pertaining to the pathophysiology, prognosis, and diagnosis of patients with diastolic dysfunction compared with normals and patients with systolic dysfunction as an etiology of heart failure. Therapeutic interventions were selected for the presence of prospective data with concrete end points such as mortality, functional class, exercise capacity, and regression of left ventricular hypertrophy.

CONCLUSION

Diastolic ventricular dysfunction is a significant problem in older people, with at least 40% of older heart failure patients having diastolic dysfunction as the etiology of their heart failure. The pathophysiology of diastolic dysfunction is varied but usually involves impaired left ventricular relaxation and/or increased ventricular stiffness, each partially related to normal aging changes, as well as underlying cardiovascular diseases. The significance of heart failure caused by diastolic dysfunction is great, with increased morbidity and mortality compared with other cardiac diseases that have the same preserved systolic function. Diagnosis of diastolic dysfunction can be clinically difficult and often requires further testing to determine if diastolic dysfunction is present. At this time, no therapy specifically treats diastolic dysfunction, but several medications, such as diuretics, calcium channel blockers, beta blockers, and angiotension-converting enzyme inhibitors, offer symptomatic relief and may prevent progression of the disorder.

Doppler evaluation of normalized peak filling rate in early neonatal period

In conclusion, the NPFR value did not change during the early neonatal period. The fact that this index does not change suggests that it might be useful as a parameter for diastolic filling, assuming that there is no significant diastolic filling change in the left ventricle over this time frame.

Quantitative hemodynamics by Doppler echocardiography: a noninvasive alternative to cardiac catheterization

Doppler echocardiography has greatly enhanced the information provided by two-dimensional echocardiography. By providing information concerning pressure gradients, intracardiac pressures, volumetric flow, and diastolic filling of the heart, most hemodynamic information that in the past could be obtained only from cardiac catheterization can now be provided accurately and noninvasively by Doppler echocardiography. Future developments in instrument technology and understanding of the various Doppler velocity curves should further aid in the ability to obtain a complete, noninvasive hemodynamic assessment of the patient with cardiac disease.

Assessment of right ventricular diastolic filling in patients with coronary artery disease

To assess right ventricular (RV) diastolic filling in coronary artery disease (CAD), with special reference to the involved lesions of the coronary arteries and left ventricular (LV) systolic function, gated radionuclide ventriculography was performed at rest in 106 patients with single-vessel CAD. Based on the site of coronary arterial involvement, patients were classified into three groups: left anterior descending CAD, right CAD, and left circumflex CAD. Patients in each group were further subdivided according to normal or decreased LV ejection fraction, resulting in six groups. Seventeen normal subjects were examined as a control group. Time-activity and its first-derivative curves were computed for the right and left ventricles. RV systolic function was normally preserved in all six groups, even when LV systolic function was damaged severely. The ratio of peak RV filling rate to peak RV ejection rate was significantly decreased in all six groups compared with that in control subjects, indicating that RV filling was impaired in patients with CAD. The ratio was below the lower limit of normal in 14 (23%) of 62 patients with normal LV systolic function and in 13 (30%) of 44 patients with impaired LV systolic function. None of the control subjects showed a decreased ratio of peak RV filling rate to peak RV ejection rate. Thus, in patients with CAD, RV filling is impaired, which may be independent of the site of coronary arterial involvement and of the LV or RV systolic function.

Rate-dependent hemodynamic responses during incremental atrial pacing in chronic constrictive pericarditis before and after surgery

Chronic constrictive pericarditis is a frequent cause of diastolic dysfunction, and results in impaired ventricular filling. Unlike in normal subjects, ventricular filling in constrictive pericarditis occurs almost entirely in the initial one third of diastole, and cardiac output is dependent predominantly on heart rate. Tachycardia impairs ventricular filling in normal subjects, but its effects in patients with constrictive pericarditis have not been studied. The effect of increasing heart rate alone with atrial pacing on the central and peripheral hemodynamics of patients with untreated chronic constrictive pericarditis before and after pericardiectomy was evaluated. Increased heart rate with atrial pacing increased cardiac output, whereas stroke volume remained unchanged up to heart rates of 140 beats/min. Further increases in heart rate resulted in reductions of cardiac output and stroke volume. There were no significant changes in ventricular filling pressures. Infusion of 300 ml of saline solution at peak pacing rates did not improve cardiac output. After successful surgical pericardiectomy, the hemodynamic effects of atrial pacing returned to normal. It is concluded that moderate tachycardia improves the hemodynamic profile of patients with constrictive pericarditis.

Time-course of left atrial performance during coronary artery occlusion followed by reperfusion in anesthetized dogs by densitometric analysis of digital atrioventriculographic images

The left atrial (LA) function during coronary artery occlusion followed by reperfusion using densitometric analysis of digital atrioventriculographic images was evaluated. Eight anesthetized dogs underwent atrioventriculography at baseline, 10 and 60 min after left circumflex coronary artery (LCX) occlusion and 5, 30, 60, and 120 min of reperfusion. Time-density curves were obtained for LA and left ventricle (LV). The ratios of passive atrial video-densitometric change (VC) to total VC (Passive Ratio), and active VC to total VC (Active Ratio) were calculated. Left ventricular ejection fraction (LVEF), peak ejection rate (PER), and peak filling rate (PFR) were derived. Active Ratio, an index of atrial contraction, increased to 144%, and Passive Ratio decreased to 75% of baseline at 60 min of LCX occlusion. Two hours after reperfusion, both Active and Passive Ratios returned to control level. While LVEF reduced to 70%, PER to 67%, LV peak positive dP/dt to 88% of baseline at 60 min after occlusion, and remained depressed at 2 h after reperfusion. However, PFR, LV peak negative dP/dt and LV isovolumic pressure decay rate showed recovery at 2 h after reperfusion. There were significant correlations between PFR and Passive Ratio (r = 0.41), and between Active and Passive Ratios (r = 0.55). Thus, time-course of recovery of LV post-ischemic systolic and diastolic function was different. Return of LA function to control level during 2 h after reperfusion may be depend on recovery of LV diastolic function.

Pitfalls in the echo-Doppler assessment of diastolic dysfunction

The Doppler echocardiographic assessment of diastolic function is an essential part of the evaluation of heart failure, pericardial diseases, restrictive and infiltrative cardiomyopathies, and many other conditions. However, the echocardiographic evaluation of diastolic function has several limitations. The sonographer and physician must understand the technical factors, the effects of physiological and pathophysiological conditions, and the dynamics of pseudonormalization, all of which affect the evaluation. This article will review the most recent data essential for the proper performance and interpretation of a transthoracic or transesophageal Doppler echocardiographic examination of diastolic function.

Asymmetrical septal hypertrophy in patients with hypertension: a type of hypertensive left ventricular hypertrophy or hypertrophic cardiomyopathy combined with hypertension?

To determine whether asymmetrical septal hypertrophy (ASH) in patients with essential hypertension (HT) is a type of hypertensive left ventricular (LV) hypertrophy or hypertrophic cardiomyopathy (HCM) combined with HT, we investigated a group of 7 hypertensive patients with ASH compared with 12 HCM patients and 10 healthy controls using radionuclide angiography and right ventricular endomyocardial biopsy. The LV time-volume curve and its first and second derivative curves were constructed from cardiac output and time-activity curves constructed by combined forward and reverse-gating from the R wave. The LV wall thickness and ejection fraction were significantly greater in both the HT and HCM groups than in the control group, whereas there were no differences in these indices between the HT and HCM groups. Rapid filling volume index and rapid filling fraction showed significantly lower values in the HCM group than in the control group (p < 0.005). In contrast to the HCM group, these indices in the HT group did not differ from those in the control group. The time to peak filling rate was prolonged in the control, hypertension, and HCM groups in increasing order. Histopathological study revealed a higher incidence of myocardial cell disarray in the HCM than in the HT group. The above results suggest that ASH in hypertensive patients is a type of hypertensive LV hypertrophy.

Quantitative dynamics of left ventricular emptying and filling as a function of heart size and stroke volume in pure aortic regurgitation and in normal subjects

Quantitative understanding of the dynamics of left ventricular (LV) emptying and filling as the left ventricle dilates but maintains ejection fraction is limited. Cine computed tomography was used to quantify peak LV emptying and filling characteristics in 30 patients with normal ejection fraction but variable end-diastolic and stroke volumes. Group I consisted of 15 normal male patients and group II of 15 male patients with chronic, well-compensated, isolated aortic regurgitation. For each patient global LV volumes, absolute peak emptying and peak early diastolic filling rates and the timing of these maximal slopes were quantified. Mean arterial pressure and heart rate were within the normal range and ejection fraction and ages similar between groups I and II. Between-group analyses showed significantly increased end-diastolic and stroke volumes in group II compared with group I but nearly identical end-systolic volumes. Likewise, absolute peak emptying and filling rates were significantly greater in group II than in group I patients. The ratio of peak emptying rate to peak filling rate remained constant between groups. Timing of peak emptying and filling were similar in both groups. Absolute LV peak emptying and filling rates were found to vary linearly with end-diastolic and stroke volumes in all subjects examined. However, referencing peak emptying or peak filling rates to end-diastolic or total stroke volumes eliminated intergroup differences. Thus, in the presence of preserved ejection fraction and normal arterial pressure, the dynamic rates of LV emptying and early diastolic filling increase in direct proportion to absolute end-diastolic and stroke volumes, but the ratio of peak emptying to peak filling rate remains constant.

Implications of third heart sounds in patients with valvular heart disease. The Veterans Affairs Cooperative Study on Valvular Heart Disease

BACKGROUND

The presence of third heart sounds in patients with valvular heart disease is often regarded as a sign of heart failure, but it may also depend on the type of valvular disease.

METHODS

We assessed the prevalence of third heart sounds and the relation between third heart sounds and cardiac function in 1281 patients with six types of valvular heart disease.

RESULTS

The prevalence of third heart sounds was higher in patients with mitral regurgitation (46 percent) or aortic regurgitation (28 percent) than in those with aortic stenosis (11 percent) or mitral stenosis (8 percent). The left ventricular ejection fraction was significantly lower (P less than 0.001) when a third heart sound was detected in patients with aortic stenosis (0.38, vs. 0.56 in those without third heart sounds) or mixed aortic valve disease (0.40 vs. 0.55). However, the ejection fraction was only slightly lower in patients with mitral regurgitation and third heart sounds (0.51 vs. 0.57, P = 0.03). The pulmonary-capillary wedge pressure was higher (P less than 0.001) when a third heart sound was detected in patients with aortic stenosis (18.6 mm Hg, vs. 12.1 mm Hg in those without third heart sounds). There was no association between the wedge pressure and third heart sounds in patients with mitral regurgitation. The prevalence of third heart sounds increased with the severity of mitral regurgitation.

CONCLUSIONS

In patients with mitral regurgitation, third heart sounds are common but do not necessarily reflect left ventricular systolic dysfunction or increased filling pressure. In patients with aortic stenosis, third heart sounds are uncommon but usually indicate the presence of systolic dysfunction and elevated filling pressure.

Changes of diastolic function induced by cigarette smoking: an echocardiographic study in patients with coronary artery disease

In 28 chronic smokers (11 women, 17 men, 53 +/- 10 years old) with coronary artery disease (greater than 75% stenosis), left ventricular (LV) relaxation and filling behavior was assessed before and after inhalation of 0.9 mg nicotine (1 cigarette) by echocardiography. The following acute nicotine-mediated changes were noted (one-sided Wilcoxon test): heart rate increased from 67 to 81 beats/min (p greater than .001); the early diastolic flow (E wave) integral decreased from 49 to 39 mm (p less than .001); the late diastolic flow integral (A wave) increased from 36 to 41 mm (p less than .01). Consecutively, the ratio between E and A wave flow integrals decreased from 1.4 to 0.9 (p less than .001); the atrial contribution to LV filling rose from 42 to 53% (p less than .001); and the isovolumetric relaxation period increased from 89 to 122 ms (p less than .001). In cigarette smokers with coronary artery disease acute administration of nicotine hence causes a shift of mitral blood flow from early (E wave) to late (A wave) diastole and a prolongation of the isovolumetric relaxation time. Thus, cigarette smoking significantly affects LV diastolic function independently of its role as a risk factor for coronary atherosclerosis.

Left atrial afterload mismatch in hypertrophic cardiomyopathy

To investigate left atrial (LA) booster pump function in hypertrophic cardiomyopathy (HC), LA and left ventricular pressure-volume loops were estimated in 5 control subjects, 6 patients with essential hypertension and 11 patients with HC. Investigation of LA preload revealed that LA pressure and volume immediately before LA contraction were both increased in patients with hypertension (10 +/- 5 mm Hg, 71 +/- 19 ml/m2) compared with control subjects (7 +/- 1 mm Hg, 59 +/- 6 ml/m2), and even more increased in patients with HC (16 +/- 7 mm Hg, 81 +/- 25 ml/m2). Investigation of LA afterload revealed that the left ventricular chamber stiffness constant was higher in patients with hypertension (0.035 +/- 0.015) than in control subjects (0.028 +/- 0.009), and even more increased in patients with HC (0.056 +/- 0.017). LA stroke work index was higher in patients with hypertension (116 +/- 34 mm Hg.ml) and HC (115 +/- 19 mm Hg.ml) than in control subjects (87 +/- 23 mm Hg.ml). Investigation of LA ejection revealed that LA stroke index was higher in patients with hypertension (24 +/- 5 ml/m2) than in control subjects (18 +/- 4 ml/m2) and patients with HC (18 +/- 2 ml/m2), and LA ejection fraction was lower in patients with HC (23 +/- 6%) than in control subjects (32 +/- 7%) and patients with hypertension (34 +/- 8%). In patients with HC, LA function curve showed a shift to the lower right, and LA stroke index was inversely correlated (r = -0.76) with LA afterload. This study suggests that LA booster pump failure due to LA afterload mismatch exists in HC.

Importance of left ventricular systolic function in the assessment of left ventricular diastolic function with Doppler transmitral flow velocity recording

To study the effect of left ventricular systolic function on the Doppler transmitral flow velocity pattern, Doppler echocardiographic variables were correlated with hemodynamic indexes in 11 control subjects and 58 patients with heart disease. All underwent cardiac catheterization performed with use of a Millar micromanometer. The time constant of left ventricular isovolumetric pressure decrease and left ventricular end-diastolic myocardial stiffness was calculated. The 58 patients were classified into two groups according to ejection fraction: group I (n = 30; ejection fraction greater than 55%) and group II (n = 28; ejection fraction less than 50%). Compared with the control subjects, patients in group I had impairment only of left ventricular relaxation (time constant 47 +/- 9 vs. 38 +/- 3 ms; p less than 0.01), whereas patients in group II had, in addition to impaired left ventricular relaxation (time constant 52 +/- 11 vs. 38 +/- 3 ms; p less than 0.01), increased preload, increased pulmonary capillary pressure (12 +/- 8 vs. 5 +/- 3 mm Hg; p less than 0.01) and increased myocardial stiffness (2,018 +/- 980 vs. 1,050 +/- 218 g/cm2; p less than 0.01). In group I, there was a significant partial correlation coefficient between the time constant and deceleration half-time (r = 0.54). In group II, a strong correlation existed between myocardial stiffness and peak atrial filling velocity (r = -0.71) and between myocardial stiffness and the ratio of peak atrial to peak rapid filling velocity (r = -0.71).(ABSTRACT TRUNCATED AT 250 WORDS)

A densitometric method for quantitative analysis of the left ventricle performance using i.v. digital subtraction angiography

In this paper we present a method we used to provide quantitative description of the systolic and diastolic temporal function of the left ventricle (LV). Additional parameters, such as peak filling and ejection rates, times to end systole and end diastole, and temporal changes in slow and fast filling are obtained. The volumes associated with these parameters are also calculated. Correlation between LV volume changes during the cardiac style and corresponding "density" variations was confirmed. Time-density curves were obtained from selected cardiac cycles in each study. We used the polynomial fitting technique to fit the time density curves and developed a computer algorithm for deriving the relevant parameters. Data from a total of 18 patients with ischemic heart or valvular diseases, who underwent I.V. ventriculography was analysed using our method. Some of these patients were forwarded for repeated digital subtraction angiography (DSA) examination before and after intervention therapy to evaluate the effectiveness of treatment. In comparison to the geometric method for the analysis of LV performance, our method is generally faster and simpler to employ. The method was effective in detecting variations in the peak ejection and filling rates in our group of patients before and after interventional therapy.

Left ventricular diastolic filling in patients with coronary artery disease without myocardial infarction

Left ventricular diastolic dysfunction at rest was studied in 24 patients with coronary artery disease but no evidence of previous myocardial infarction. Seven patients with normal coronary arteries were studied as control. Diastolic filling was analyzed by the serial left ventricular volume and 14 radial axes from the gravity point of the left ventricle with cine left ventriculography. There were no differences in the systolic function between coronary artery disease and the normal control. Peak filling rate was decreased significantly in the groups with left anterior descending artery disease (LAD, p less than 0.05) and multivessel disease (MVD, p less than 0.05), but not in the group with right coronary artery disease (RCA). Time to peak filling rate was prolonged in each group of LAD (p less than 0.05), RCA (p less than 0.05), and MVD (p less than 0.001), compared with controls. The time-volume curve showed disturbed rapid filling in the LAD and RCA groups, and also both depressed rapid and slow filling in the MVD group. In the LAD group, the filling fraction was decreased significantly at the time of 25% of the diastolic period (p less than 0.001) and radial distension to the anterior wall was decreased at the time of 25%, 50%, and 75% of the diastolic period, compared with controls. In the RCA group, the filling fraction (p less than 0.001) and radial distension to the posterior wall were decreased only at the time of 25% of the diastolic period. In the MVD group, filling fraction and radial distension to the most wall were decreased at 25%, 50%, and 75% of the diastolic period.(ABSTRACT TRUNCATED AT 250 WORDS)

The inheritance of left ventricular structure and function assessed by imaging and Doppler echocardiography

The heritability of left ventricular structure and function was studied in 53 pairs of monozygotic and dizygotic twins, aged 18 to 31 years, by means of M-mode and Doppler echocardiography. A significant fraction of the phenotypic variances of left ventricular wall thickness was explained by genetic variance. For the left ventricular internal dimension, however, no genetic effect was found after correction for body weight. After appropriate adjustment a genetic component of 32% was found for aortic peak flow velocity, 55% for stroke distance, and 47% for minute distance. The early and late diastolic peak flow velocities at the mitral valve showed a genetic component estimated at 43% and 26%, respectively. The inheritance of the late/early diastolic peak flow velocity ratio was estimated at 53%. In conclusion, these data suggest a significant genetic component for left ventricular structural features but not for cavity dimension. A significant influence of heredity was detected for left ventricular inflow and outflow characteristics.

Doppler echocardiographic transmitral peak early velocity does not directly reflect hemodynamic changes in humans: importance of normalization to mitral stroke volume

Doppler echocardiographic transmitral peak early velocity normalized to the time-velocity integral during diastole is equivalent to volumetric peak filling rate normalized to stroke volume. To compare the pathophysiologic validity of normalized and nonnormalized peak early flow velocity, pulsed Doppler echocardiography with simultaneous high fidelity left ventricular pressure measurements was performed in 52 patients with coronary artery disease. Left ventricular loading conditions were changed by intravenous administration of norepinephrine in 15 patients and synthetic atrial natriuretic polypeptide in 15 others. Norepinephrine increased nonnormalized and normalized peak early flow velocities in association with significantly elevated end-diastolic, peak systolic and mitral valve opening pressures and decelerated the time constant of left ventricular isovolumetric pressure decline. Atrial natriuretic polypeptide did not change either nonnormalized or normalized peak early flow velocity, despite significant reductions in end-diastolic, peak systolic and mitral valve opening pressure and an accelerated time constant. Normalized peak early flow velocity showed the highest univariate correlation with long-term change in mitral valve opening pressure (n = 52, r = 0.67, p less than 0.0001). It provided a modest univariate correlation (n = 30, r = 0.74, p less than 0.0001) with immediate change in mitral valve opening pressure during norepinephrine infusion, whereas this correlation was lower (n = 30, r = 0.57, p less than 0.001) during polypeptide infusion. However, multivariate regression analysis relating normalized peak velocity with long- and short-term changes in end-diastolic, peak systolic and mitral valve opening pressures, time constant and constant of left ventricular chamber stiffness improved the correlation coefficients (r = 0.80 to 0.85, all p less than 0.0001). In contrast, neither univariate nor multivariate correlations of nonnormalized velocity with long- and short-term changes in these hemodynamic variables were satisfactory. Thus, nonnormalized peak early flow velocity does not directly reflect underlying hemodynamic changes in humans. Normalization to mitral stroke volume clarifies the dependence of peak early flow velocity on the determinants of early diastolic filling. When left ventricular early diastolic filling is evaluated by Doppler echocardiography, normalized peak early flow velocity should be taken into consideration.

Mechanism of augmented left atrial pump function in myocardial infarction and essential hypertension evaluated by left atrial pressure-dimension relation

To analyze left atrial (LA) pump function in normal subjects, in patients with essential hypertension and in patients with a healed myocardial infarction, LA dimension (aortic-root echogram) and pressure (catheter-tip manometer) were simultaneously recorded in 25 patients (8 normal subjects, 7 with hypertension and 10 with myocardial infarction). The pressure-dimension relation of the left atrium was composed of 2 loops: the A loop (expressing the pump function of the left atrium) and the V loop. LA dimension at the beginning of active LA shortening was significantly greater in hypertensive subjects (33 +/- 3 mm) and in those with myocardial infarction (32 +/- 4 mm) than in normal subjects (28 +/- 3 mm) (p less than 0.01, p less than 0.05, respectively). The area of the A loop significantly increased in subjects with hypertension (48 +/- 3 mm Hg.mm, p less than 0.01) and in subjects with myocardial infarction (29 +/- 10 mm Hg.mm, p less than 0.05), compared with normal subjects (20 +/- 8 mm Hg.mm). The mean fractional shortening velocity of the left atrium significantly increased in subjects with hypertension, compared with normal subjects and those with myocardial infarction (p less than 0.05 for both). LA peak wall tension during the LA active contraction period significantly increased with hypertension and with myocardial infarction, compared with normal subjects (p less than 0.01, p less than 0.05, respectively). The area of the A loop was directly proportional to the LA dimension at the beginning of active LA shortening (r = 0.53), p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Left ventricular diastolic function during short-term positive end-expiratory pressure ventilation in dogs

Simultaneous recordings of left ventricular (LV) pressure and volume (sonomicrometry) were made in acutely instrumented dogs anaesthetized with pentobarbital during intermittent positive pressure ventilation with zero and positive end-expiratory pressure at 10 and 20 cmH2O (PEEP10 and PEEP20). Pericardial pressure was measured continuously in order to obtain transmural LV pressure. PEEP reduced LV end-diastolic volume and transmural pressure significantly. This was accompanied by significantly reduced stroke volume. LV peak diastolic filling rate, calculated as dV/dtmax, was significantly reduced when PEEP was applied, independent of LV volume alterations. LV diastolic compliance, assessed by the slope of LV pressure-volume relationship during LV filling, decreased significantly with increasing PEEP levels. A positive correlation was observed between reductions in peak diastolic filling rate and reductions in end-diastolic volume. The reduced peak diastolic filling rate, on the other hand, was closely correlated to reduced LV diastolic compliance. Isovolumetric relaxation rate (T) increased slightly at the highest PEEP level. This could, however, not be related to a reduced LV diastolic filling rate. The close association between reduced LV diastolic compliance and reduced diastolic filling rate may indicate that a tamponade-like effect is involved in the reduction of LV preload observed during PEEP ventilation.

Patterns of global and regional systolic and diastolic function in the normal right ventricle assessed by ultrafast computed tomography

A detailed evaluation of global and regional systolic function and diastolic filling of the human right ventricle has not been previously reported. Ultrafast computed tomography enables simultaneous imaging of the right and left ventricles at an 8 mm slice thickness with a scanning rate of 17 frames/s (50 ms acquisition intervals). In 10 normal men (mean age 26 +/- 4 years) early diastolic filling data were fit to a third order polynomial curve and the peak rate of diastolic filling and time to peak filling were determined globally and regionally at three distinct ventricular levels (apex to base) within each ventricle. The right and left ventricular stroke volumes were not statistically different (89 +/- 8 ml and 90 +/- 8 ml, p = NS), neither were the peak filling rates as referenced to the stroke volume (4.9 +/- 0.9 and 5.3 +/- 0.8 stroke volumes/s, p = NS). Time to peak filling rate was not different between the two ventricles (154 +/- 33 and 161 +/- 18 ms, p = NS). However, reference of stroke volumes and absolute peak filling rates to end-diastolic volumes demonstrated lower dynamic values for the right ventricle (ejection fraction: right ventricle 57 +/- 4%; left ventricle 68 +/- 5%, p less than 0.05, and peak filling rate: right ventricle 2.7 +/- 0.4 end-diastolic volumes/s; left ventricle 3.6 +/- 0.5, p less than 0.05, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Doppler assessment of right ventricular filling dynamics during volume loading in ischemic heart disease

To assess the effects of volume loading on right ventricular (RV) filling dynamics, the RV inflow pattern was recorded using pulsed Doppler echocardiography (PDE) during dextran infusion in 7 normal subjects (Group I) and 24 patients with ischemic heart disease. The patients with ischemic heart disease were divided into three groups according to the left ventricular (LV) and RV ejection fractions (EF). Group II consisted of 11 patients whose LVEF and RVEF exceeded 50%. Group III consisted of 7 patients whose LVEF was lower than 50% and RVEF was higher than 50%. Group IV was comprised of 6 patients whose LVEF and RVEF were lower than 50%. Peak flow velocity of the RV rapid filling wave in early diastole [R(T)] and that of the atrial contraction wave [A(T)] were measured, and the ratio of A(T) to R(T) [A(T)/R(T)] in each cardiac cycle was calculated. In some of the subjects, simultaneous right-sided cardiac catheterization was performed with a Swan-Ganz thermodilution catheter. The LV and RV function during volume loading were calculated according to the following formulae: delta Stroke volume index (SVI)/delta pulmonary artery wedge pressure (PAWP) and delta SVI/delta right atrial pressure (RAP), respectively. After dextran infusion, R(T) increased significantly in Groups I, II, and III, but not in Group IV. The A(T) and A(T)/R(T) ratio remained unchanged in all groups. The percent change of the R(T) correlated well with delta SVI/delta RAP (r = 0.56, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)