Effects of venous return reduction in hypertensive patients: is there a Doppler diastolic dysfunction index independent of preload reduction?

Operative contractility: A functional concept of the inotropic state

1. Initial unsuccessful attempts to evaluate ventricular function in terms of the 'heart as a pump' led to focusing on the 'heart as a muscle' and to the concept of myocardial contractility. However, no clinically ideal index exists to assess the contractile state. The aim of the present study was to develop a mathematical model to assess cardiac contractility. 2. A tri-axial system was conceived for preload (PL), afterload (AL) and contractility, where stroke volume (SV) was represented as the volume of the tetrahedron. Based on this model, 'operative' contractility ('OperCon') was calculated from the readily measured values of PL, AL and SV. The model was tested retrospectively under a variety of different experimental and clinical conditions, in 71 studies in humans and 29 studies in dogs. A prospective echocardiographic study was performed in 143 consecutive subjects to evaluate the ability of the model to assess contractility when SV and PL were measured volumetrically (mL) or dimensionally (cm). 3. With inotropic interventions, OperCon changes were comparable to those of ejection fraction (EF), velocity of shortening (Vcf) and dP/dt-max. Only with positive inotropic interventions did elastance (Ees) show significantly larger changes. With load manipulations, OperCon showed significantly smaller changes than EF and Ees and comparable changes to Vcf and dP/dt-max. Values of OperCon were similar when AL was represented by systolic blood pressure or wall stress and when volumetric or dimensional values were used. 4. Operative contractility is a reliable, simple and versatile method to assess cardiac contractility.

Effect of the Valsalva manoeuver on diastolic filling indices in patients with essential hypertension

In some hypertensive patients, echocardiographic examination does not reveal any pathologic finding in spite of a documented blood pressure elevation. In our study, we investigated the effect of preload reduction with Valsalva manoeuver on transmitral flow velocities in hypertensive patients with normal mitral flow pattern and compared the results with a healthy control group. Sixty-eight patients without evidence of coronary artery disease or heart failure (28 female, 40 male, age 50 +/- 7) were divided in two groups according to their E/A ratio as those with diastolic dysfunction (n = 36) and without diastolic dysfunction (DD(-): n = 32). DD(-) patients and the control group (n = 20) performed Valsalva manoeuver and their pulsed-Doppler mitral flow measurements were repeated at the strain phase. During Valsalva manoeuver, E wave velocity decreased in all subjects. In the controls, peak A velocity showed a similar decline and E/A ratio remained over 1.0. However, in 72% of DD(-) patients A velocity did not change or increased and their E/A ratio fell below 1.0. In 47% of the patients with an E/A ratio reversal after Valsalva manoeuver, myocardial perfusion scintigraphy revealed reversible defects whereas none of the patients whose E/A ratio remained over 1.0 had perfusion defects. It is concluded that: (1) in hypertensive patients with normal E/A ratio Valsalva manoeuver should be performed in order to unmask a probable false normal finding, (2) an important percent of hypertensive individuals have left ventricular relaxation abnormalities, and (3) diastolic dysfunction develops together with a decrease in coronary reserve.

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.

Atrial ejection force: a noninvasive assessment of atrial systolic function

OBJECTIVES

The purpose of this study was to define atrial ejection force and to develop a method for its noninvasive measurement from echocardiographic data.

BACKGROUND

Assessment of diastolic function through measurement of the components of ventricular filling has largely neglected the vigor of atrial systole, in part because this has been difficult to quantify. However, atrial ejection force, defined as that force exerted by the left atrium to accelerate blood into the left ventricle during atrial systole, can be assessed noninvasively by combined two-dimensional imaging and Doppler echocardiography. This index of atrial function, based on classic newtonian mechanics, provides a physiologic assessment of atrial systolic function.

METHODS

To evaluate the usefulness of atrial ejection force, we studied the return of left atrial ejection force in 29 patients after elective cardioversion for atrial fibrillation. Transmitral Doppler inflow patterns at rest were assessed immediately after cardioversion and at 24 h, 1 week, 1 month and > 3 months later. A healthy adult group (n = 10) served as control subjects.

RESULTS

After successful cardioversion, atrial ejection force was significantly depressed compared with that in the control group (5.2 +/- 6.8 vs. 16.3 +/- 4.7 kdynes; p < 0.0001). Over successive weeks, atrial ejection force improved in the subgroup of patients who remained in sinus rhythm (n = 18), whereas no improvement was seen during the period of maintained sinus rhythm in the patients with subsequent reversion to atrial fibrillation (n = 11).

CONCLUSIONS

Atrial ejection force provides a physiologic assessment of atrial systolic function and is a potentially useful index for assessing atrial contribution to diastolic performance. In patients who successfully underwent cardioversion from atrial fibrillation, atrial ejection force improved over several weeks only in the subgroup in which sinus rhythm was maintained.