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The present article discusses the thoughts of Gregory of Nazianzus in relation to virtual reality especially man-made virtual reality in all its forms. We argue that the benefits of virtual reality, such as freedom, imagination, creativity can be paradoxically curtailed by virtual reality itself, since it is highly subjective and as its medium shows, can be an a priori matrix and prison for the human being. Gregory of Nazianzus, building his theology on a firm basis on substance and contemplation, offers a way out, where one acknowledges everything around us as beneficial and beautiful and therefore free, but this must be based on a firm grounding of truthfulness and guidance offered by an all-encompassing form of Divine love and creativity.

An enlargement of the diameter of the right descending branch (RDB) of the pulmonary artery in chest radiographs may serve as a sign of pulmonary arterial hypertension. We tried at first to establish exactly the normal values for men and women of different age, analysing the radiographs of 112 healthy subjects. There is a relationship of RDB diameter to sex and age. We compared the RDB diameters in 95 men suffering from chronic bronchitis with the pulmonary arterial pressure, flow, and resistance, and with the right ventricular work: a highly significant relationship of RDB diameter to all but the blood flow values was found. Considering (in men over 40 years of age) a diameter of the RDB of 18 mm. or more as pathological, the reliability of the diagnosis of pulmonary hypertension in chronic bronchitis was 72·2% with readable films, or 64·2% when not reliably readable chest films were included. Nevertheless, a similar comparison in patients with mitral stenosis indicates that the radiographic picture of pulmonary hypertension differs according to the initial disease. Here we discuss the factors which may influence the RDB diameter. [ABSTRACT FROM PUBLISHER]

The authors present their experience with total hip replacement in patients with ankylosing spondylitis. In the period of 1985-1997 they performed in total 66 total hip replacements in 41 patients. Of the total number of the used implants 24 were fully cemented (the average follow-up - 13 years), 3 were hybrid and 39 cementless (the average follow-up - 6 years). The results of total hip replacements were assessed on the basis of Harris score (HS). The outcomes of the two subgroups, i. e. cemented and cementless implants, were statistically evaluated and compared. The group of hybrid implants was not statistically evaluated due to a small size of the subgroup. In both evaluated groups of implants the results were very favourable (the average HS value in cemented: 86,2 in cementless: 86,4). The occurrence of periarticular ossifications was minimal in both groups. Of the post-operative complications we recorded one case of displacement of the implant which was solved by closed reduction under general anesthesia. Two cases required re-operation of the loosened cementless cup. There occurred no infect. On the basis of the evaluation of the average 13-year results of cemented implants the use of this type of total hip replacement in patients with M. Bechterev is recommended. The question remains whether the same positive values will be produced after the same time interval also by cementless implants as we still do not have results from a 10-year follow-up. Key words: ankylosing spondylitis, total hip replacement.

Pulmonary artery input impedance (PAII) expresses the opposition of pulmonary vessels to pulsatile blood flow, in the same way that vascular resistance expresses opposition to steady flow. PAII spectrum includes information concerning not only the mean blood flow, pressure and resistance, but also proximal vessels stiffness, pulse wave velocity and arterial wave reflection. It is an adequate expression of the right ventricular afterload, and it is quite suitable for the description of the right-ventricular-pulmonary arterial interaction. Pulsatile properties must be taken into account, for instance, to understand the effects of pulmonary vasodilation on cardiac output. Characteristic PAII is increased in pulmonary hypertension due to stenosis, pulmonary thromboembolic disease, and in unexplained pulmonary hypertension.

Using two-dimensional echocardiography (ECHO), the authors examined within one week preceding right-sided catheterization of the right ventricle (RV) 44 patients. Of three tested ECHO techniques for calculation of right ventricular volumes and/or function the best correlations were obtained by the method of evaluation of area-length of the right ventricle from two orthogonal projections (apical 4-cavity and subcostal with visualization of the outflow portion of the RV). The following correlations were assessed: telediastolic volume--r = 0.831, telesystolic volume--r = 0.815 stroke volume--r = 0.810 and ejection fraction (EF)--r = 0.752 (p less than 0.001 for all correlations). The tested method enables us at the same time to screen at least existing right ventricular dysfunction (sensitivity 0.68; specificity 0.82). In the presence of tricuspidal insufficiency (TI) increase in right ventricular function occurs which may mask its existing failure (dependence of EF on the mean pressure level in pulmonary artery was proved only in patients without TI--r = 0.594). We assume that information on right ventricular function is important not only in diseases affecting primarily the right heart but also in advanced stages of left-sided failure. Follow-up of the natural course of the disease and the effect of provided treatment by the non-invasive ECHO method is thus useful not only in research but also in clinical practice.

We employed two-dimensional echocardiography for the assessment of right ventricular (RV) volumes and/or function in a series of 44 patients. The results of three different echocardiographic approaches were compared with the data obtained from single-plane RV angiography following ultrasound within a 7-day interval. Only the echocardiographic area length method with two orthogonal imaging planes employed (apical 4-chamber and subcostal projections) yielded the beneficial results. The correlations between echocardiographic and angiographic RV volume estimates were rather high (end-diastolic volume: r = 0.83, end-systolic volume: r = 0.82, stroke volume: r = 0.81) and satisfactory in ejection fraction (r = 0.75). Using the method mentioned, the differentiation of patients with an angiographic evidence of RV failure (echocardiographic ejection fraction less than 0.55) from those without it was possible with a sensitivity of 0.68 and a specificity of 0.82. Concerning the clinical impact of the presented study, we can recommend the technique in question as a screening procedure for the detection of changes in RV function exceeding 12% (95% confidence limits).

The effect of nitrates was monitored in 16 patients with precapillary, and in 12 patients with postcapillary pulmonary hypertension (PH). The patients had haemodynamic examination on acute administration of 10 mg of isosorbide nitrate (ID) in infusion and after 2-month therapy with 120 mg of isosorbide dinitrate retard daily. Acute ID administration decreased filling pressure of both ventricles, pulmonary and aortic pressure, pulmonary and systemic resistance and increased blood flow. No significant difference was found between the two types of PH. Long-term administration resulted in a statistically significant decrease in filling pressure (in both ventricles) and pulmonary pressure, even though the decrease was less pronounced than those seen following acute administration. Again, no statistical differences were noted between the two types of PH. While acute administration of nitrates decreases both preload and afterload, chronic administration decreases only preload. The implications of this finding for therapeutic practice are discussed.

Using the pulsed Doppler system with a high reparative frequency (HPRF), the authors made within 1 hour and 3 days after diagnostic right-sided catheterization 38 measurements of the trans-tricuspid pressure gradient in 31 consecutive patients. To the gradient calculated from the absolute velocity of flow through the jet of tricuspid regurgitation the authors added two different arbitrarily determined pressure values in the right atrium to obtain the systolic pressure in the right ventricle--RVSP (which assuming the absence of an obstruction between the right ventricle and pulmonary artery equals the systolic pressure in this artery). The calculated RVSP from the Doppler assessment correlated highly significantly with the directly manometrically obtained values of the same indicator (r = 0.973; p less than 0.001). An even closer correlation was obtained when using a differentiated estimate of the pressure in the right atrium/according to the filling of the jugular veins) (r = 0.977; p less than 0.001). From the RVSP values the authors tried to predict the presence of pulmonary hypertension (PH) diagnosed from the median pressure in the pulmonary artery (PAP greater than or equal to 20 mm Hg which was considered conclusive). Using the arbitrarily assessed range of systolic PH greater than 35 mm Hg, the sensitivity of the ultrasonographic estimate was 79% with a 60% specificity, while when the criterium of greater than 40 mm Hg was used, the corresponding values were 64% and 90%.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of 2-month treatment with isosorbide dinitrate (120 mg day-1), nifedipine (2 x 20 mg day-1) and their combination has been assessed in 16 patients with mild to moderate chronic cardiac failure. Isosorbide dinitrate decreased right atrial (-23%), pulmonary wedge (-20%) and pulmonary arterial (-17%) pressures but did not significantly change either cardiac output or systemic and pulmonary vascular resistance. Nifedipine increased cardiac output (+13%) and decreased systemic and pulmonary vascular resistance (both -17%) with no change of pressures. Combined therapy with both drugs decreased ventricular filling pressures (-8% and -15%), systemic (-20%) and pulmonary (-13%) arterial pressures, increased cardiac output (+26%) and decreased both systemic (-29%) and pulmonary (-29%) vascular resistances. Changes during exercise were almost the same as at rest. The effect of both drugs was more pronounced in patients with more severely pathological haemodynamic measurements before treatment. We conclude that combined treatment with both preload- and afterload-reducing agents can preserve or even potentiate a favourable haemodynamic effect of individual drugs.

Using Doppler method (HPRF and CW regime), the authors assessed the peak velocity of flow in an aortal spurt in 41 patients with aortal stenosis. For calculation of the transaortal pressure gradient they used a modified Bernoulli equation. The values of the calculated gradients were compared with those obtained by direct manometric assessment during catheterization of the heart after an interval of several hours to five days. Combination of two Doppler techniques correlated closely with direct assessment (r = 0.811; p less than 0.001). By application of the continuity equation in the best records of spectral analysis of velocity curves the authors calculated in 8 patients the area of the reduced aortal orifice which was very close to the area calculated by means of Hakki's formula from direct haemodynamic indicators (r = 0.948; p less than 0.001). In 33 patients the authors quantified by Doppler method the severity of aortal regurgitation from the ratio of forward and backward flow in the descending portion of the aortal arch (expressed as the % regurgitation fraction--RF). The RF values correlated well with the angiographic semiquantitative scale of severity of aortal insufficiency (r = 0.805; p less than 0.001), although they enabled the authors only to make a partial differentiation of haemodynamically severe regurgitations and mild or insignificant ones. The authors conclude that the Doppler approach makes it possible to evaluate sufficiently accurately the severity of aortic valve disease (in insufficiencies the authors recommend a more comprehensive approach), which when correctly applied and interpreted, can make non-invasive clinical diagnosis more accurate and thus permits also more accurate indication of surgical treatment of these patients.

Decompensated cor pulmonale is a clinical syndrome manifested by signs of congestive heart failure in pulmonary disease. The authors emphasize that the haemodynamic characteristic of the syndrome differs substantially from the classical picture of chronic heart failure: the cardiac output is usually normal at rest and sometimes even during exercise, signs of impaired contractility of the right ventricle are absent and the effect of cardiac glycosides is minimal. It is possible that the clinical syndrome of decompensated cor pulmonale is caused mainly by respiratory failure and subsequent impaired function of some organs, in particular the kidney.