Pulmonary hypertension associated with human immunodeficiency virus infection. Report of two cases and review of the literature.

Recent reports have suggested a possible association between HIV-1 infection and "idiopathic" pulmonary hypertension (PH), but the pathogenetic role of the viral agent has not been fully defined yet. We report the cases of two white males positive for human immunodeficiency virus type 1 (HIV-1) who presented with clinical and hemodynamic diagnosis of pulmonary hypertension. They were heterosexual, non-hemophiliac, heroin abusers with no signs of clinical AIDS. Neither one of the patients had opportunistic lung infections or any other cause of secondary pulmonary hypertension. In one case, peculiar clinical and electrocardiographic features of PH were associated with signs of thrombotic thrombocytopenic purpura (TTP). The association between PH and HIV-1 infection might be explained by a severe alteration of pulmonary endothelial cell homeostasis secondary to HIV-1 viral infection.

The mechanism of the physiologic disappearance of the third heart sound with aging.

The third heart sound (S3) is often present in children and adolescents but is not present in most adults. Applying at the left ventricle a mathematical model, the mechanism of the disappearance of S3 was studied employing the frequency analysis of the sound and echocardiographic data. The existence of a significant correlation between the spectrum energy of S3 and the diameter and thickness of the left ventricle at the moment of S3 in 25 healthy subjects (aged 21 +/- 7 years) allowed us to interpret the origin of S3 based on a viscoelastic oscillating system. Once the left ventricle starts vibrating it behaves as a simple physical model composed of a mass (m), a spring (k) and a viscous element. The abrupt deceleration of the blood mass (m) against the left ventricular walls (k) triggers the vibration of the system according to the equation Fd = 1/2 pi.square root of k/m.square root of 1 - zeta 2, where Fd is the natural damped frequency and zeta is the damping factor. The equation shows that the vibrating system can oscillate only if zeta is < 1. During the growth of the individual the increased myocardial mass may lead to augmented viscous forces causing a gradual increase in zeta until the system becomes overdamped and consequently unable to vibrate causing the disappearance of S3.

An estimation of the left ventricular diastolic function from the spectral analysis of the fourth heart sound. A Doppler validated study in hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is a typical primary cardiac disease characterized by diastolic abnormal function due to both prolonged relaxation and decreased compliance (Sanderson et al., 1977; Spirito & Maron, 1990). Since the contribution of the atrial systole to ventricular filling is usually increased, the appearance of a fourth heart sound (S4) is a common finding in HCM. This sound is related to the ventricular compliance and to the atrial contractility. It is generated during the rapid setting into vibration of the left ventricular walls that results from the rapid rush of the blood due to the atrial contraction (Nishimura et al., 1989; Tavel, 1978). The aim of this study is to look for relationships between the frequency peak of S4 and various mono- and two-dimensional echocardiographic parameters in order to identify those cardiac structures involved in its genesis and obtaining an estimation of the stiffness of the acoustic vibrating system with a simply vibratory model (Baracca et al., 1991).

The response of the ageing heart to regular physical exercise. An echo and Doppler study.

In upper middle age healthy subjects the functional cardiac reserve is known to be decreased (Port et al., 1980; Aubert et al., 1994). On the other hand regular physical exercise improves the cardiovascular function (Nishimura et al., 1980). The aim of this study was to establish whether regular physical exercise is associated with a significant change in the ageing process of the cardiovascular system.

Genesis and acoustic quality of the physiological fourth heart sound.

The genesis of the fourth heart sound (S4) is commonly related to the rapid set in vibration of the left ventricular walls, resulting from the rapid inflow of the blood due to the atrial contraction (Nishimura et al., 1989). S4 can be recorded in normal young subjects as an expression of physiologic atrial dynamics but it is more common in pathologic conditions characterized by decreased ventricular distensibility (Tavel, 1978). Employing the spectral analysis of heart sounds (Longhini et al., 1979; Longhini et al., 1981; Aubert et al., 1984) we searched for the relationship between different components of the frequency spectrum of S4 and various echocardiographic parameters, with the aim of identifying the cardiac structures involved in its genesis (Longhini et al., 1989; Baracca et al., 1991).

Sudden cardiac arrest in a teenager as first manifestation of Takayasu's disease.

A 14-year-old girl was rescued from a sudden cardiac arrest at school. Aortography disclosed mild aortic root dilation with aortic valve incompetence and subocclusion of coronary ostia and left common carotid artery. An emergency aortocoronary bypass operation was undertaken, but the patient did not recover from cardiopulmonary bypass. Postmortem disclosed massive myocardial infarction. The microscopic feature of arterial involvement was consistent with giant cell Takayasu's arteritis. The abrupt clinical presentation in this teenager with coronary ostial subocclusion is very unusual.

A new, noninvasive method to monitor the aging of bioprosthetic valves in the mitral position.

Bioprosthetic valves undergo a tissue degeneration of unpredictable onset and amount. This process alters the structure and function of the valve and consequently shortens its lifespan. The echocardiographic technique usually used in the follow-up of these patients does not provide accurate information concerning the amount of prosthesis tissue degeneration. A new technique has been developed based on the spectral analysis of the first heart sound, which enables the evaluation of prosthetic leaflet stiffness. The Young's modulus (E) and stress (s) of the valve leaflets were derived as functions of the inner diameter of the heterograft and its primary vibration frequency, which can be obtained from the frequency spectrum of the first heart sound. Thirty-six patients with a mitral bioprosthetic valve were studied. Fifteen had thickening or calcification, or both, of the valvular leaflets at echocardiographic examination. In patients with a normal valve, E and s showed a good correlation with the duration of implantation (r = 0.909, p < 0.001; and r = 0.828, p < 0.001; respectively). Patients with abnormal leaflets had values of E and s that were greater than the theoretical values expected for their duration of implantation. The procedure is sensitive, accurate and easy to perform, and enables monitoring of the aging of the prosthetic valve and early identification of valve tissue degeneration. Together with echocardiography, this procedure yields a more complete evaluation of prosthetic valves for the follow-up of patients.

Non-invasive estimation of the diastolic elastic and viscoelastic properties of the left ventricle.

The present study applies a non-invasive method to the quantitative evaluation of left ventricular stiffness in normal subjects and in patients with ischaemic heart disease (IHD). We have studied 20 patients with IHD and 25 healthy subjects. The third heart sound (S3) was detectable in all patients. We have correlated the energy spectrum of S3, divided into 15 Hz bands, with a series of echocardiographic parameters. The existence of a significant correlation between the spectrum energy and the diameter and thickness of the left ventricle at the moment of S3 allowed us to explore the possibility of interpreting the origin of S3 based on a mathematical model. Our hypothesis has been that, once the left ventricle starts vibrating, it behaves as a simple physical model composed of a mass and an elastic element. To this purely elastic model one can add a factor accounting for viscosity, with a damping effect, to obtain a more complex viscoelastic model. The stiffness coefficient 'k' was computed in both models from the peak frequency of S3 and the left ventricular mass at the moment of S3. Furthermore, in the viscoelastic model, the damping element 'c' was also computed. Both parameters--k and c--were significantly increased in the group with IHD compared with the control group. Although a simplification of the vibrating system, these models make it possible to obtain non-invasively information on the characteristics of the left ventricle through the combined use of echocardiography and spectral analysis of S3.

The effect of captopril on peripheral hemodynamics in patients with essential hypertension: comparison between oral and sublingual administration.

A comparative study of the effects of oral and sublingual captopril on the hemodynamics of the peripheral musculocutaneous vasculature was carried out on ten patients with essential hypertension. Both routes of administration of captopril lead to lower blood pressure and decreased regional resistance, and to an increased arterial blood flow at rest. The first measurable effect and the peak effect on blood pressure and peripheral hemodynamics appear slightly earlier with sublingual administration. The data provided in this study support the usefulness of the sublingual route in clinical situations in which oral administration of captopril is not feasible.

Clinical value of the pitch of the third heart sound in ischemic heart disease.

The study investigates the genesis of the third heart sound (S3) in ischemic heart disease based on a mass-spring model. In such a system, the natural frequency of vibration, Fn, depends on the elastic constant, k, and the mass, m, according to the following relationship: Fn = 1/2 pi square root of k/m. To identify the cardiac structures representing k and m, the correlations between the energy of the S3 spectrum and the echocardiographic parameters were searched for. The results are consistent with a model in which k is represented by the thickness of the left ventricle and m by its blood content. The k/m ratio emerges as an important determining factor of the acoustic quality of S3, and yields information on the dysfunction of the left ventricle in ischemic heart disease.

A mass-spring model hypothesis of the genesis of the physiological third heart sound.

A study on the genesis of the third heart sound (S3) based on the mass-spring model is presented. In such a system the natural frequency of vibration depends on the stiffness constant and the mass according to a physical law. The amplitude versus frequency spectra of S3 of 19 patients were obtained using the FFT algorithm together with mono- and two-dimensional echocardiographic parameters. Each echo parameter was correlated with the relative energy contained in each of the 15 Hz bands in which the normalized average spectrum of S3 of each subject was divided. The relative energy of each band was related to echocardiographic parameters. Significant correlation coefficients were found between the diameter of the left ventricle measured at the end of the rapid filling phase. The thickness of the posterior wall and of the interventricular septum at this moment, and the energy contained in certain frequency bands. The statistical correlations we have revealed are consistent with the model postulated in our hypothesis.