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Biomedical subjects

I Dvorák

Publications and source records attributed to I Dvorák.

At least 19 recordsLinked to original sources
PubMed1996

[Comparison of dynamic and isometric loading in echocardiographic examinations in patients with ischemic heart disease].

The objective of the work was to compare functional indicators of the left ventricle during isometric (HG) and dynamic (Ergo) echocardiographic load examinations in patients with different grades of ischaemic heart disease. In group A they compared results in 34 patients with affection of three coronary arteries and in group B 15 patients with 1-2 coronary arteries affected. They evaluated the systolic, diastolic blood pressure, heart rate (HR), the index of the diastolic end volume EDV/m2, the index of the systolic end volume ESV/m2, Limacher's index for evaluation of left ventricular motility and the left ventricular ejection fraction (EF) at rest and after both types of loads. The EDV/m2 index increased in group A by 5.2 ml during an isometric load and by 10.4 ml during a dynamic load, in group B it increased by 1.6 and 7.0 ml resp. The values of the ESV/m2 index increased in group A by 8.5 ml during the isometric load and by 14.0 ml during the dynamic load, in group B by 4.1 and 10.8 ml resp. EF values at rest were similar in both groups: group A: 51.4%, B: 51.5%. During the isometric load the EF declined to 45.3% in group A and to 47,1% in group B. During the dynamic load the EF declined to 42% in group A and 42.5 in group B. The dynamic load produces, as compared with the isometric one, a statistically more significant drop of Limacher's index and greater volumetric changes of the left ventricular cavity in the group with 1-2 affected coronary arteries, as compared with the isometric load. In patients with three affected coronary arteries the volumetric changes during an isometric load are comparable with changes after a dynamic load.

Coronary Disease↗
PubMed1996

[Importance of dipyridamole transesophageal echocardiography in the diagnosis of ischemic heart disease].

The importance of dipyridamol echocardiography in the diagnosis of ischaemic heart disease (IHD) was described repeatedly. Nevertheless in roughly 20% patients the transthoracic echocardiographic examination at rest is inaccurate or cannot be carried out because the ultrasonic visibility is poor. In these patients transoesophageal dipyridamol echocardiography (TEE Dip) can provide a suitable alternative. This is why the authors evaluated 36 patients examined on account of IHD before and after administration of 0.80 mg/kg dipyridamol. The left ventricle was visualized in the transgastric short axis and from the apical view. Angiography revealed significant stenosis of the coronary arteries in 23 patients. In 18 patients after administration of dipyridamol new motility disorders developed, in 5 patients with motility of the left ventricular wall, impaired at rest, no new disorder of kinetics developed, i.e. the test was falsely negative. Thirteen patients had no signs of stenosis of the coronary arteries and three developed disorders of the motility of the left ventricular wall. The sensitivity of TEE Dip for the diagnosis of left ventricular ischaemia was 78% and the specificity 79%. Dipyridamol load transoesophageal echocardiography is a method suitable for clinical application with a still satisfactory sensitivity and very good specificity and it can be implemented without involving the risk of serious side-effects.

Adult↗
PubMed1995

[The effect of dipyridamole on pulmonary venous flow in patients with ischemic heart disease].

In 56 patients with ischaemic heart disease the authors evaluated the blood flow in the pulmonary veins, using transoesophageal echocardiography by the pulsed Doppler technique in the left upper pulmonary vein. They assessed the peak systolic velocity (pVS), the systolic integral time-velocity (S-VTI), the peak diastolic velocity (pVD) and the integral time velocity in the diastolic part of the flow (D-VTI). They found a statistically significant correlation between the ratio pVS/pVD and the LVEDP assessed by the invasive method (r = 0.812). In 36 patients the authors evaluated the flow rate and time-velocity integral at rest and after administration of 0.78 mg/kg dipyridamol by the i.v. route. In 17 patients with affections of 2 or 3 coronary arteries (group A) after the administration of dipyridamol an increase of the maximal flow rate occurred in the diastolic portion of the flow (at rest 54.7 +/- 12.5, after dipyridamol 64.9 +/- 14.8 cm/s). The systolic flow velocities did not change in this group of patients (at rest 52.2 +/- 3.0, after dipyridamol 54.3 +/- 14.0 cm/s). In 19 patients with a negative coronarographic finding (group B) or with stenosis of one coronary artery after dipyridamol administration the systolic peak velocity increased (from 58.0 +/- 10 to 70.2 +/- 14.8 cm/s). The pVD values increased slightly after dipyridamol (at rest 42.5 +/- 14.3, after dipyridamol 52.1 +/- 15.6 cm/s).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗
PubMed1993

[Evaluation of physical rehabilitation in myocardial revascularization using echocardiography].

The authors investigated 155 patients, mean age 50.6 years, after revascularization of the myocardium. The group was divided at random into a group with a high intensity of physical rehabilitation (A) and a medium and low rehabilitation group (B). The rehabilitation programme comprised physical exercise at least three times per week for at least 30 mins. with a dynamic load up to 80% of the maximum heart rate in group A and up to 40% in group B. The mean initial haemodynamic indicators in both groups were equal (LVEDP 17.5 mm Hg and 16.5 resp. and EF 52.3% and 50.5% resp. in group A and B). Six months after revascularization the mean values of work tolerance increased in group A more than in group B (58.6 kJ, as compared with 44.2 kJ) and this difference is even greater after three years (70.4 kJ as compared with 51.5 kJ). The mean values of the ejection fraction (EF) at rest do not differ in the two groups after 6 months nor after 3 years (51.3% in group A, as compared with 54.6% in group B after 6 months, and 55.2% vs. 53.7% resp. after three years). The EF after a dynamic load after 6 months and 3 years does not differ in the two groups either (57.2% vs. 56.4% after 6 months and 55.1% vs. 54.5% after three years). Similar results were also obtained on evaluation of the mobility index of the walls at rest and after a dynamic load.(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiography↗
PubMed1993

[Significance of pulmonary vein flow for the determination of left ventricular filling pressure].

The aim of the submitted study was to evaluate the blood flow in the pulmonary veins by transoesophageal Doppler echocardiography which is the ideal method for recording the blood flow in the pulmonary veins as the ultrasound probe is closely behind the left atrium. In 35 patients with ischaemic heart disease the authors evaluated the blood flow in the pulmonary veins to assess whether the rate of the blood flow in these vessels can serve a non-invasive estimate of the end-diastolic pressure in the left ventricle (LVEDP). It was revealed that venous blood flow has in the majority of cases two anterior peaks during ventricular systole, one anterior peak during diastole and one negative peak during atrial contraction. In patients with normal LVEDP the peak rate and integral time-velocity of the flow curve is greater during systole, while in patients with a higher LVEDP these parameters are higher during diastole. Dopplerian assessment of the flow in the pulmonary veins is safe, relatively non-invasive and simple. This method makes possible rapid visual estimates of the end-diastolic pressure in the left ventricle.

Blood Flow Velocity↗
PubMed1992

[Transesophageal stress echocardiography].

The authors submit their initial experience with the work protocol of transoesophageal loading echocardiography, which they used in 148 patients. The method is meant in the first place for individuals where the records of classical transthoracic echocardiography in 10-25% are difficult to visualize by echocardiography or patients who for any reasons cannot be subjected to common loading examinations. The informative capacity of this method is almost 100%. It makes it possible to evaluate every accurately filling and ejection indicators as well as changes in the motility of cardiac walls.

Contraindications↗
PubMed1992

[Echocardiographic evaluation of the left ventricle in mild hypertension treated with physical exercise].

The authors submit findings of haemodynamic changes during long-term treatment of mild hypertension by physical training. Using this method, blood pressure was normalized in all subjects. The authors conclude that physical activity has a similar impact on the haemodynamics of mild hypertension as drugs which reduce the tension of the sympathetic nerve. A surprising finding was the diminution or complete disappearance of cardiac hypertrophy in this treatment.

Adult↗
PubMed1991

Bopindolol: Czechoslovak experience with a new beta blocker in the treatment of hypertension.

Bopindolol is a nonselective beta blocker with mild intrinsic sympathomimetic activity. One of the drug's main benefits is its prolonged effect, lasting for 24 hours, which makes it possible to administer bopindolol in a single daily dose, a fact that may improve patient adherence to therapy. A double-blind study was performed in two centers, comparing bopindolol with metoprolol in 86 hypertensive patients. Baseline diastolic blood pressure (BP) was 100 to 120 mm Hg. The effects of bopindolol or metoprolol on BP and heart rate were similar: return to normal values was achieved in 70% of patients with either drug. A 6-month study at another center found that bopindolol did not affect the levels of total cholesterol, low-density and high-density lipoprotein cholesterol or triglycerides. Another 12-month study documented a decrease in total cholesterol, apolipoprotein (apo) A1 and apo B. The apo A/B ratio rose, thus improving the atherosclerotic index. No deterioration of glucose tolerance or immunoreactive insulin response to glucose was seen after 6 months of bopindolol administration. Bopindolol satisfactorily modifies not only resting but also exercise BP during isometric and isotonic load, thus reducing BP fluctuation during physical activities of the hypertensive patient. The drug exerts no effect on renal and liver function, electrolyte balance and hematologic parameters. Bopindolol is a very useful drug of first choice in mild and moderate hypertension. Bopindolol's main advantages include its prolonged action, good tolerance and a beneficial effect on risk factors of atherosclerosis (lipid and carbohydrate metabolism).

Adolescent↗
PubMed1991

Antihypertensive effect of isradipine on blood pressure at rest and during exercise.

After three months of treatment with isradipine, 20 patients with mild hypertension had reduced their resting blood pressure (BP) from 157/103 to 132/85 mm Hg and their BP during isometric exercise from 192/124 to 166/105 mm Hg. The isradipine dose necessary to normalize BP (both at rest and post-exercise) was 1.25 mg twice daily (2 x 1/2 tablet) in 50% of patients and 2.5 mg twice daily (2 x 1 tablet) in 25%. In the remaining 25% of patients, isradipine was combined with 1 mg/day bopindolol. There were virtually no accompanying side effects; in particular, reflex tachycardia was negligible or absent. It is concluded that isradipine is a reliable antihypertensive treatment in mild-to-moderate hypertension.

Adrenergic beta-Antagonists↗
PubMed1991

Pharmacokinetics and tolerance of 7-methoxytacrine following the single dose administration in healthy volunteers.

7-methoxy-tetrahydroaminoacridine (7-MEOTA) is a new reversible cholinesterase inhibitor. Forty-eight young male volunteers divided into six dosage groups were included into a single-dose pharmacokinetic study with either oral (p.o.) or intramuscular (i.m.) administration. The dose of 7-MEOTA was 2, 4 or 8 mg/kg body weight p.o. or 0.5, 1 or 2 mg/kg body weight i.m. in the respective six dosage groups. The plasma levels data were fitted to an open one-compartmental model. The compound showed cholinomimetic adverse effects in 2 subjects with the blood levels exceeding 1,500 micrograms/l. The red blood cells levels paralleled those in plasma and were 2.5 times higher. The tmax was 4 hours and 1 h, t1/2 8.7 +/- 3.9 hours and 6.5 +/- 5.8 hours in case of p.o. and i.m. administration, respectively. The apparent clearance (D/AUC) was 5 times higher following p.o. administration, reflecting the differences in bioavailability.

Administration, Oral↗
PubMed1990

Isradipine in monotherapy and in combination with bopindolol: results of a 3-month multicentre study in hypertensives.

The antihypertensive effect and safety of treatment of hypertension with isradipine, a Ca antagonist of dihydropyridine group in monotherapy and in combination with the betablocker bopindolol was assessed in a multicentre study joined by six Czechoslovak centres. When administered alone to 102 patients with essential hypertension stages I and II, isradipine was effective in 59%. Forty-one per cent of patients required combined therapy. The treatment led to a marked decrease in diastolic BP in smokers and non-smokers alike. A significant rise in ALP was observed during therapy in both therapeutic regimens. A significant decrease in cholesterolaemia was found in patients treated with the isradipine-bopindolol combination. No serious adverse effects were seen during three-month follow-up.

Administration, Oral↗
PubMed1989

[Use of the postural test in stress echocardiography].

The authors introduced and evaluated the clinical importance of the echocardiographic positional test for the detection of left ventricular insufficiency after exercise. They found that in decompensated ischaemic patients, contrary to healthy subjects, left ventricular ejection indicators deteriorate. Latent left ventricular weakness in ischaemic patients without clinical signs of heart failure is revealed by positional reduction of the rate of shortening of the circumferential fibre. The authors conclude that this test does not fully replace the work load examination. The change of position is, however, a simple, preliminary functional test which may be useful in patients with ischaemic heart disease for checking treatment, rehabilitation and the selection of subjects for further aimed examinations.

Coronary Disease↗
PubMed1989

Analysis of metabolic systems with complex slow and fast dynamics.

We briefly review the results of other authors concerning the analysis of systems with time hierarchy, especially the Tikhonov theorem. A theorem, recently proved by the authors, making possible rigorous analysis of systems with complex fast dynamics is stated and discussed. A model example of a simple enzymatic reaction with product activation and slow (genetically driven) enzyme turnover is rigorously studied. It is shown that even in such a simple model there exist certain regions of parameters for which fast variables oscillate. Thus the classical Tikhonov theorem is not applicable here and we are forced to use another method--for example the author's presented theorem--or a purely numerical solution. These two methods are compared.

Enzymes↗
PubMed1989

[Diastolic function of the left ventricle in incipient hypertension].

The authors provide evidence that changes of diastolic indicators precede in incipient hypertension the impaired left ventricular function. In marginal hypertonics and in particular in stage 1 hypertonics they found by echocardiography that, as compared with healthy normotonic subjects, sings of impaired relaxation in the early diastole. This is apparent from the significant prolongation of the time constant of relaxation at rest and the maximal speed of relaxation which are due to the early filling of the left ventricle. To increase the sensitivity of the echocardiographic examination of left ventricular functions the isometric loading test proved useful.

Adult↗
PubMed1989

[Echocardiographic orientation evaluation of the function of the left heart ventricle].

The authors discuss the possibility to make use of a simple echocardiographic indicator of left ventricular function--the angle formed by the anterior cusp of the mitral valve and the line of the interventricular septum, assessed from a four-chamber tracing (angle M). Based on echocardiographic examination of 87 subjects they established their own standards. They consider values above 30 degrees as pathological, suggesting impaired left ventricular function. The M angle correlates significantly with invasive (final diastolic pressure in the left ventricle, ejection fraction) and with non-invasive (top speed of shortening of the circumferential fibre) indicators of left ventricular function. The authors assume that this simple, quick screening of left ventricular function will prove helpful, in particular in subjects where visualization by one-dimensional echocardiography from a parasternal approach is difficult. In practice it can be also applied for evaluation of left ventricular function during loads, in particular in dynamic echocardiography.

Cardiomyopathy, Dilated↗
PubMed1989

[Changes in blood pressure in mild forms of hypertension after long-term physical training].

The authors submit the results of a long-term study of the treatment of mild hypertension by physical training. Its advantage, as compared with medicamentous treatment, is the physiological effect on the organism, its financially unpretentious character, and if the population is seriously informed, its wide application. The authors found in general a poor approach to physical activity, in particular among young people due to lack of information on the importance of physical activity. They conclude that physical training is the method of choice in the treatment of mild forms of hypertension. The blood pressure attained normal levels after this treatment in liminal hypertonics as well as hypertonics stage I.

Adult↗