Biomedical subjects

J Malík

Publications and source records attributed to J Malík.

At least 19 recordsLinked to original sources

PubMed2005

Second derivative of the finger arterial pressure waveform: an insight into dynamics of the peripheral arterial pressure pulse.

The study investigated second derivative of the finger arterial pressure waveform (SDFAP) in 120 healthy middle-aged subjects and in 24 subjects with essential hypertension. SDFAP consists of 5 sequential waves 'a'-'e'. Their normalized magnitudes (B/A, C/A, D/A, and E/A) were calculated. In multivariate regression analysis, B/A and C/A correlated only with age. D/A independently correlated with age, heart period, mean blood pressure (MBP), body height, and gender. E/A independently correlated with age and MBP. D/A and E/A were higher (0.42+/-0.16 vs. 0.33+/-0.14, p = 0.05 and 0.63+/-0.15 vs. 0.45+/-0.14, p < 0.001), while B/A and C/A were lower (1.04+/-0.16 vs. 1.20+/-0.17, p = 0.002 and 0.09+/-0.15 vs. 0.26+/-0.20, p = 0.001) in hypertensives compared to sex- and age-matched controls. After the adjustment for MBP, heart period, and body mass index (ANCOVA), independent discriminative power was preserved only for indices B/A and C/A (p = 0.001 and 0.021, respectively). Therefore, B/A and C/A provide additional information about simple clinical characteristics and might reflect the structural alteration of the arterial wall in hypertensive subjects.

Adult↗

PubMed2004

[Wall shear stress and endothelium].

Blood flow influences the luminal side of vessel wall by a frictional force known as wall shear stress (WSS). This local hemodynamic factor is an important determinant of endothelial gene expression and of endothelial phenotype. The effect of WSS depends on its magnitude and direction, as well as on the characteristic of vessel geometry and blood flow. WSS seems to be a critical determinant of vessel caliber, vascular remodeling and restenosis and plays a role in intimomedial hyperplasia. Research is concentrated especially on the influence of WSS on atherosclerotic plaque formation.

Endothelium, Vascular↗

PubMed2003

[Ultrasonography of complications in vascular access for dialysis: initial experience].

BACKGROUND: Vascular access complications represent leading morbidity of hemodialyzed patients. Duplex Doppler ultrasonography is used rarely in the diagnosis of vascular access complications, despite its simplicity and widespread availability. Our first experience with this method is described, namely the most frequent indications, findings and the access blood flow correlation. METHODS AND RESULTS: 356 examinations of both natural and polytetrafluoroethylene (PTFE) accesses at 193 patients were performed. The 7.5 MHz linear array ultrasound transducer of Hewlett-Packard SONOS 2000 device was used. Both arterial and venous parts of fistulas were examined in all cases. Screening examinations represented the most frequent indication, the hemodynamically significant stenosis the most frequent finding. Only 12.5% of PTFE-shunts and 25.8% of natural fistulas were described as normal. Mean blood flow through antebrachial and brachial accesses was 575 and 1070 ml/min, respectively. CONCLUSIONS: Prevalence of vascular access complications (especially that of stenoses) is high. Wider use of this method could bring significantly improved care for the dialysed patients.

Arm↗

PubMed2003

[Would ultrasonography contribute to the early detection of clinically silent dialysis access stenoses?].

BACKGROUND: Stenoses are leading factors limiting dialysis vascular access patency. Both physical and haemodynamic examinations are used in stenoses screening. To estimate potential advantage of ultrasonography as a screening measure, we calculated both sensitivity and specificity of clinical (nephrological) diagnoses of access stenoses compared with ultrasound. METHODS AND RESULTS: 268 examinations of 193 subjects were included into this comparison. Linear-array 7.5 MHz ultrasound probe were used for whole-length access examination. Sensitivity of clinical examination was 35.8%, specificity 92.8%. Sensitivity did not differ significantly according to the stenosis localization. CONCLUSIONS: Ultrasound use in dialysis access screening would considerably increase the number of stenoses diagnosed in-time. On the contrary, clinical suspicion on access stenosis is highly specific, therefore it is not indispensable to confirm it by ultrasound.

Adolescent↗

PubMed2003

[Total body composition in adult patients with growth hormone deficiency before and after its administration].

Effect of growth hormone (GH) on the growth and development of children is generally known. Effects of GH in adults are favorable, though. The aim of the work was to verify effects of GH administration on body composition in adult patients with GH deficit (GHD). The authors examined 15 adult patients with GHD originated in 13 of them in adulthood and in two of them in childhood. Their mean age was 43.9 +/- 11.3 years, the mean body mass was 80.0 +/- 15.2 kg. The GH deficit was verified by the stimulation insulin tolerance test. For the period of 12 months, they were subcutaneously administered recombinant human GH in a substitution dose of 0.5 to 1.5 IU/m2 body surface/day. A stable substitution of the hormone was applied for the period of at least six months in all these patients provided any deficit of other hormones had not been demonstrated. The examination by whole-body dosimeter Lunar DPX-L was made in the patients before the GH treatment began and after 12 months of therapy. It enabled to determine the amount of lean body mass (LBM) and fatty mass. After 12 months of GH treatment the mean level of insulin-like growth factor (IGF-I) was increased (P = 0.002). A statistically significant increase of total LBM (48.6 +/- 9.8 vs. 50.8 +/- 9.9 kg, P = 0.004) developed, the fatty mass did not change. Nine of these 15 patients were further followed and the administration of GH proceeded for six months. The densitometric examination was repeated, but no change of LBM was observed. The administration of GH was halted and after the period of 12 months the whole-body densitometric examination was done. The increase of LBM lasted. The amount of fat mass did not change, a decrease of fatty mass was observed after the GH administration ended. After 12 months of GH treatment there was also an increase of maximal output reached on bicycle ergometer (157.3 +/- 34.2 vs. 197.5 +/- 68.1 W, P = 0.006). A positive correlation between LBM and maximal output reached on bicycle ergometer before GH administration (r = 0.58, P = 0.02) was observed. A favorable effect of the substitution dose of GS administered to adult patients with GHD on the increase of LBM and physical output was confirmed.

Adult↗

PubMed2002

[Heart rate turbulence--a new ECG predictor for risk of sudden death].

Heart Rate Turbulence (HRT) is a newly described physiological chronotropic response of sinus rhythm following a single ventricular premature beat (VPB) consisting of early acceleration and later deceleration of heart rate. Using two large independent cohorts of postinfarction patients, the absence of HRT was retrospectively validated to be a potent multivariate risk predictor, stronger than a number of currently available risk stratifiers. Although exact pathophysiological mechanism of HRT remains speculative, it is now believed that HRT arises from the haemodynamic changes and baroreceptor reflexes that occur following a VPB. Therefore, HRT descriptors (Turbulence Onset and Turbulence Slope) may serve as very reasonable, Holter--based surrogates of baroreflex sensitivity available in clinical practice. The aim of this review is to summarise the current knowledge on pathophysiological mechanisms of HRT and to discuss practical problem of its detection.

Death, Sudden, Cardiac↗

PubMed2000

[Function and dysfunction of the endothelium].

Endothelium is a multi-functional barrier separating blood from interstitium. It plays a role in coagulation, inflammation, angiogenesis and it has vasomotor functions. The endothelial dysfunction can be considered as an initial stage of atherosclerosis. Using morphological and biochemical methods it is possible to study the influence of cardiovascular risk factors on the vessels and the effect of therapeutic interventions. A short review of endothelial functions, endothelial dysfunction and its quantification methods is presented in this article.

Blood Coagulation↗

PubMed1998

[Relation of the thickness of the intima and media of the common carotid artery, atherosclerotic plaque in the carotids and manifestations of atherosclerosis in the vessels of the lower extremity in comparison to coronary atherosclerosis].

BACKGROUND: Concomitant occurrence of carotid atherosclerosis, coronary artery disease (CAD) and peripheral vascular disease (PVD) has been described in a number of studies. The objective of the present trial was to assess the degree of correlation between atherosclerosis of the carotid beds as well as PVD and the extent of CAD. METHODS AND RESULTS: Carotid morphologies of 170 patients in total (121 men, 49 women), ranging between 23 and 81 years in age were assessed ultrasonographically. Their carotid beds searched for plaques, stenoses and occlusions. In all patients intima-media thickness (IMT) of the common carotid artery (CCA) were measured ultrasonographically. In addition, case histories of PVD were taken. CAD was proved angiographically in 138 patients. Plaques in carotid beds were found in 98 patients, carotid artery stenoses > 75% were found in 4 patients whereas complete carotid occlusion was not detected in any patient. Clinically manifested PVD was found in 20 patients. A significant difference in IMT of the CCA was assessed by t-test between patients having and not having CAD (0.67 +/- 0.16 mm vs. 0.87 +/- 0.24 mm; P < 0.0001). The correlation between the IMT of the CCA and extent of CAD was weak (r = 0.30, p < 0.01). A positive correlation between carotid plaque occurrence and the number of CAD-affected arteries was statistically assessed (Trend test: P = 0.0001). The sensitivity of incidence of plaques on the carotid beds for prediction of CAD was 64%, the specificity 72%, the positive predictive value 91% and the negative predictive value 32%. The sensitivity of clinically manifested PVD for prediction of CAD was 15%, the specificity 100%, the positive predictive value 100% and the negative predictive value 21%. CONCLUSIONS: The authors confirmed a statistically significant but weak correlation between IMT of the CCA and severity of CAD. They found a positive trend between the occurrence of carotid plaques and the number of CAD-affected arteries. The presence of carotid plaques and clinically manifested PVD were confirmed as a reliable positive predictive factors for CAD.

Adult↗

PubMed1998

[Treatment of hypopituitarism in adults with growth hormone improves improves the thickness of the arterial intima].

BACKGROUND: Increased mortality of hypopituitary adults with atherosclerotic vascular disease is commonly explained by growth hormone deficiency and forms the main argument for the growth hormone replacement. At the same time it is known that the growth hormone-IGF-I axis stimulates the vessel wall proliferation as an initial step of atherosclerosis. Investigation of the arterial intima thickness in hypopituitary adults with duplex ultrasound system and its follow up during the growth hormone therapy may clarify these effects of growth hormone on the vessel wall. METHODS AND RESULTS: Luminal diameter, maximal blood flow velocity and arterial intima thickness of common carotid arteries was measured with colour duplex ultrasound system in 15 adults with hypopituitarism before and after one year therapy with recombinant growth hormone. The results were compared with healthy controls matched for gender, age, blood pressure and weight. The luminal diameter did not changed during the therapy with growth hormone and was the same in patients and controls. Maximal blood velocity in hypopituitary patients before the therapy was lower than in control subjects (74.8 +/- 13.9 cm/s vs. 94.0 +/- 21.0 cm/s), but the statistical difference was only borderline. Arterial intima thickness was significantly thinner in hypopituitary patients when compared with controls (0.56 +/- 0.1 mm vs. 0.71 +/- 0.12 mm, p < 0.001) but became thicker after the treatment and was not any more different from the controls (0.56 +/- 0.1 mm vs. 0.66 +/- 0.1 mm, p < 0.001). CONCLUSIONS: In hypopituitary adults the arterial intima thickness of common carotid arteries is less than in healthy controls. The reduced thickness was normalised after one year treatment with growth hormone. Atheromatous plaques were not found either before or after the treatment. Duplex ultrasound measurement may be one of the means of checking of the effects of growth hormone therapy.

Adult↗

PubMed1997

[Cardiogenic shock in acute myocardial infarct].

Based on clinical records (three years) the authors assessed the characteristics of patients with cardiogenic shock during myocardial infarction (48 of 270 patients with infarctions, i.e. 18%). The mortality of these patients was 77%. The incidence of cardiogenic shock evidently rose with age in both sexes and amounted to as much as 35% in the most advanced age groups. Other "risk factors" for the development of shock were arterial hypertension and diabetes. By dividing patients with myocardial infarction and cardiogenic shock into first infarctions (55%) and re-infarctions (45%) it was found that other risk factors for the development of cardiogenic shock are anterior localization of the infarction in first infarctions, and in re-infarctions it is in particular the number of previous infarctions (as they increase the size of the infarction focus). The authors point out that it is essential to pay increased attention to patients with acute infarction to prevent the development of cardiogenic shock (attempt thrombolytic treatment, treatment focused on prevention of ischaemia and arrhythmias). Apply also during its treatment thrombolysis or possibly PTCA.

Adult↗

PubMed1995

[Initial experience of an endocrinologist with the treatment of hypophyseal adenomas with the Leksell gamma knife].

BACKGROUND: Surgery of pituitary adenomas is not quite satisfactory so far and in some patients it is associated with a high risk. Conventional radiotherapy is only partly successful. Only few hospitals have experience with treatment of pituitary adenomas with Leksell's gamma knife. The objective of the presented paper is to give an account of the authors' own results of treatment of pituitary adenomas by irradiation with Leksell's gamma knife. METHODS AND RESULTS: The treated group comprised 13 patients (6 women, 7 men, 25-72 years old, median 44 years) with a pituitary adenoma. Hormonally active acromegaly was recorded in 9 patients, a prolactinoma in one female patient, afunctional adenoma in 3 patients. Twelve patients had been operated already previously, 3 of them twice. For visualization of the pituitary magnetic resonance (NMR) was used on a Magnetom apparatus 1.5 Tesla, Siemens Co. before surgery and one year after surgery. As hormonal indicators the following were examined: growth hormone (GH) profile in the course of the day and during the thyroliberin test (TRH), insulin-like growth factor I (IGF I), the prolactin level, the thyrotropin level (TSH) during the thyrotropin releasing hormone test (TRH) test the thyroxine level (T4) and the triiodothyronine level (T3), the plasma concentration of adrenocorticotropin (ACTH), the cortisol level, plasma testosterone level and 17-beta estradiol level. Complete recovery was achieved only in one female patient with acromegaly 18 months after irradiation, and in one patient with a prolactinoma a partial decline of hormone levels was recorded without detectable changes in the size of the adenoma. Only one female patient developed hypopituitarism. No other complications were recorded. CONCLUSIONS: Stereotactic irradiation with Leksell's gamma knife is valuable for treatment of pituitary adenomas and it is well tolerated therapy. Its effect is manifested only after several months. Complications in the sense of hypopituitarism may occur.

Adenoma↗

PubMed1988