Early diastolic left ventricular inflow pressures in normal subjects and patients with dilated cardiomyopathy. Reconstruction from pulsed Doppler echocardiography

From digital image processing of colour Doppler M-mode maps to noninvasive evaluation of the left ventricular diastolic function: a dedicated software package

Noninvasive estimation of diastolic pressure gradients has recently been validated using the space-temporal velocity distribution available from colour Doppler M-mode (CDM). However, the methods currently applied for analysing CDM patterns of left ventricular (LV) filling have limitations, such as lack of automation, subjective variability and limited use of digital velocity map. For this reason, we have developed software able to acquire and process the CDM maps; thus, providing an easily interpretable graphical and numerical display. The pressure field is obtained by approximating the derivatives with centred finite differences via the incompressible Navier-Stokes equations. After digital filtering of the noise and the removal of the colour black spots, the velocity field is utilised to compute the pressure gradient field and the pressure values by spatial integration. It is concluded that automatic quantification of colour CDM patterns is feasible and will be a strategic tool in the investigation of one of the most intriguing topics in cardiology.

Reduced early diastolic inflow velocities in the antero-posterior transverse direction in the left ventricle of patients with dilated cardiomyopathy

In patients with dilated cardiomyopathy (DCM), the left ventricular (LV) inflow jet is narrow and has a high pressure gradient. A pulsed Doppler restrictive transmitral flow pattern is a characteristic feature of severe left ventricular disease. However, Doppler flow analysis is limited by the angle between the blood flow jet and the ultrasonic beam. In this study we used gated magnetic resonance imaging (MRI) to investigate the inflow velocity in the LV transverse directions during early diastole in patients with DCM.

METHODS

We studied 10 patients with DCM (mean age: 47 y). Ten age-matched healthy volunteers were also examined. Gradient echo images of the LV were obtained. Left ventricular short axis phase contrast images were obtained at the level of the mitral valve tip and 1 cm inside the LV. Long axis images were also obtained. Through-plane peak velocities at peak early diastolic filling were measured along the LV long axis, antero-posterior short axis, and right-left short axis. Blood velocity was measured in 50 ms blocks.

RESULTS

Early diastolic inflow velocity along the long axis, especially at the center of the LV, was well preserved in DCM. However, the inflow velocity in the antero-posterior transverse direction of the LV (i.e., in the direction of mitral valve excursion) was significantly reduced in DCM.

CONCLUSIONS

Early diastolic inflow velocity in the antero-posterior transverse direction of the LV is reduced in patients with DCM indicating that the vector component of the forces acting in the antero-posterior transverse direction of the LV may be decreased in patients with DCM during early diastolic filling.

Comparison of ventricular pressure relaxation assessments in human heart failure: quantitative influence on load and drug sensitivity analysis

OBJECTIVES

We contrasted various methods for assessing ventricular pressure decay time constants to test whether sensitivity to slight data instability or disparities between model-assumed and real decay are systematically altered by cardiac failure. We hypothesized that such discrepancies could result in apparent increased relaxation sensitivity to load and drug stimulation.

BACKGROUND

Deviation of relaxation behavior from model-assumed waveforms may be worsened by failure, enhancing instability and apparent load and drug sensitivity of commonly used indexes.

METHODS

Pressure-volume relations were measured in patients with normal (n = 14), hypertrophic (hypertrophic cardiomyopathy [HCM], n = 15) and dilated-myopathic (dilated cardiomyopathy [DCM], n = 37) hearts before and during preload reduction or inotropic stimulation. Relaxation parameters (monoexponential [ME] model assuming zero-T(in) or non-zero-T(D), T(F) asymptote:, hybrid logistic-T(L), linear-T(LR), and pressure halftime-T(1/2)) were contrasted regarding sensitivity to slight data range manipulation and loading or drug changes.

RESULTS

In DCM, T(D) and T(F) prolonged 15% to 25% (p < 0.0001) by deletion of only 1-2 data points, whereas this had minimal effect on controls or HCM. This stemmed from systematic deviation of relaxation from an ME decay in DCM. T(1/2) and T(in) were highly sensitive to pure pressure offsets, whereas T(L) was most stable to both manipulations in all hearts. As a result, T(D) and T(F) appeared to be much more sensitive to systolic load in DCM than T(1/2) or T(L) and disproportionately sensitive to increased cyclic adenosine monophosphate (cAMP).

CONCLUSIONS

Relaxation consistently deviates from an ME decay in DCM resulting in instability and amplified relaxation systolic load or drug dependence of ME-based indexes in failing versus control (or HCM) hearts. The hybrid-logistic method improves quantitative analyses by providing more consistent data fits with all three heart types.

Magnetic resonance velocity mapping of transtricuspid velocity profiles in dilated cardiomyopathy

To investigate the velocity profiles and jet sizes of transtricuspid inflow by magnetic resonance imaging (MRI), we examined seven dilated cardiomyopathy (DCM) patients (mean age 37 +/- 15 years) and 20 normal subjects (mean age 32 +/- 7 years). We used a Siemens Magnetom Impact Expert (1.0 T) together with a surface receiver coil. Electrocardiographic gating, triggered by the R wave, was performed. Cine gradient echo images were obtained in the short axis of the right ventricle. Velocity mapping of right ventricular inflow was obtained at peak early diastolic filling. Velocity profile curves across the tricuspid inflow were obtained at 1-cm intervals from the tricuspid ring up to 3 cm into the cavity. Maximum/mean velocities in both groups were 1.1 +/- 0.1 at the ring level, unchanged at 1 cm from the tricuspid ring, and thereafter increased to 1.4 +/- 0.3 at 2 cm and 1.5 +/- 0.3 at 3 cm as peak velocity fell. Jet cross-sectional area was 10.4 +/- 2.1 cm2 at the ring level, and was unchanged at the 3-cm level in the normal subjects. However, in patients with DCM it was smaller than that in normals, and decreased in proportion to the distance from the tricuspid ring. Thus, tricuspid inflow velocity showed a relatively flat profile at the tricuspid ring and tip levels, becoming more dispersed at 2 and 3 cm from the ring. The cross-sectional area of the right ventricular inflow jet in the DCM patients was small and decreased in proportion to the distance from the tricuspid ring, although it appeared to be relatively constant in normal subjects.