Biomedical subjects

P Dobsák

Publications and source records attributed to P Dobsák.

5 recordsLinked to original sources

PubMed2003

Total artificial heart: the adaptation and pathophysiological deviations in the recipient.

In the short historical review the principal technical and pathophysiological approaches of the Czech total artificial heart (TAH) research are emphasized. Survival was endangered by arterial and venous hypertension, especially the central venous pressure (CVP) increase, mineralization of driving diaphragms, thromboembolization, and infection. By the appropriate combination of antihypertensive, antimineralization, and anticoagulation treatment and of measures against infection, the survival of the experimental calves was increased (the longest one was 314 days of pumping). Technical and constructional improvement of the blood pumps was another cause of successful experiments. All details are issued in the references.

Adaptation, Physiological↗

PubMed2003

Microvessels of bulbar conjunctiva in UPTAH goats.

Aiming to observe directly the microcirculation after total artificial heart (TAH) implantation, we performed a long-term follow-up in 2 goats using conjunctival angioscopy. A short segment of parallel arteriole and venule was photographed and analyzed on computer picture program (magnification 40x). Three main parameters were measured: arteriole diameter, venule diameter, and arteriovenous ratio (A/V ratio). The intrathoracically implanted TAH was the undulation pump total artificial heart (UPTAH) with cardiac output of 100 ml/kg/min. To stabilize the peripheral hemodynamics a 1/R biofeedback control system was used. Our results provided only elementary data about morphology of bulbar microvessels. The main finding was the tendency to general vasoconstriction, more intensive on the venous side (*P < 0.05 in one goat). We did not observe any pathological shapes (e.g., tortuosities, varicosities, or sludge); this result could be attributed to the high effectivity of 1/R control method. These preliminary results should be considered only as an attempt to apply the widely used clinical method of conjunctival angioscopy to the conditions of TAH.

Animals↗

PubMed2003

[Combined training in patients with systolic left ventricular dysfunction].

The objective of the work was to evaluate the effect of eight-week combined training on the performance, aerobic capacity and basic haemodynamic parameters in patients with systolic dysfunction of the left ventricle and to assess its safety. The investigation comprised 26 patients, men mean age (x +/- SD) 61.8 +/- 11.1 years with coronarographically verified chronic ischaemic heart disease and with a left ventricular ejection fraction lower than 40% (EF 35 +/- 4%). Before the beginning and after completion of the rehabilitation programme (eight weeks) a spiroergometric examination was made, up to the symptom-limited maximum. Fitness elements were included after 2 weeks of aerobic training. The lesson lasted 60 mins. and included warming up (10 mins.), aerobic load on an ergometer with an intensity of the load at the level of the anaerobic threshold (20 mins.), the stage of fitness training on a combined training machine (20 mins) and the relaxation stage (10 mins). In the fitness stage the patients started to exercise at the 30% level, after two weeks at the 60% level 1-RM (one repetition maximum) The results showed after eight-week combined training a significant (p < 0.05) increase of the maximum achieved performance (from 104 +/- 27 to 132 +/- 32 W) in patients with systolic left ventricular dysfunction. There was a significant increase in the capacity of the transport system expressed by the value of the maximum oxygen uptake (from 1545 +/- 312 to 1740 +/- 359 ml.min-1) and MET (from 5.3 +/- 1.3 to 6.0 +/- 1.4). There was a significant decrease of the blood pressure at rest, systolic and diastolic, and of the baseline value of the heart rate at rest and of the "product rate, pressure"--RPP. Changes in the EF were not significant.

Exercise Therapy↗

PubMed2000

Electronmicroscopic changes in selected vital organs after long-term total artificial heart pumping in animal experiments.

Electronmicroscopic (EM) evaluation of selected vital organs (liver, kidney, lung) informs us about otherwise hardly detectable changes during total artificial heart (TAH) pumping. In our experiments, we compared 2 groups of long-surviving animals in which the TAH TNS-BRNO pneumatic device was implanted (TNS-BRNO-II and VII in 45 experiments, TNS-BRNO-III in 1 experiment, and TNS-BRNO-VIII in 1 experiment). In 4 experiments, the Rostock TAH (NABEL, TAH Research Center, Rostock, Germany) was implanted. One group of 22 animals with an average survival of 162 days (the longest, 293 days) was submitted to an antihypertensive treatment; another 1 of 29 calves with an average survival of 98 days (the longest, 173 days) was untreated. The evaluation was performed using a scale (0 to 3) based on very precisely fixed criteria. EM pathologic changes documented various stages of ischemic damage. Except for the liver, no significant difference was found between both groups, despite the substantially prolonged survival in the treated group. Very important was the general state of mitochondria, endoplasmic reticulum, and nucleus. Further, the state of glomerular podocytes in the kidney and the state of interalveolar septa and of pneumocytes constituting the air-blood barrier for gas exchange in the lungs are especially important. In some animals of both groups, the EM findings were completely normal, especially in the lung.

Animals↗

PubMed1994

Instrumentation of ramus circumflexus compromises the innervation of coronary artery and myocardium.

A fine non-compressing methacrylate ring was implanted on the ramus circumflexus (RC) in 13 dogs. After the animals survived 7-14 days, the distribution and the rate of the Wallerian degeneration was studied in coronary arteries and myocardium by means of the formaldehyde induced fluorescence (FIF) technique and the transmission electron microscopy. The density of vasomotor innervation in the main arterial trunks was expressed as the number of transsected terminals per 1 mm2 of the transversally sectioned media; the density of adrenergic terminals in the myocardium was determined by the point-counting method. A compact scar encompassing the ring was found. The scar compressed some perivascular nerves. As a consequence, by about 40% of terminals degenerated in the RC. The innervation of the branching of this artery was compromised as well. Moreover, the density of nerve terminals in myocardium decreased around the whole circumference of the ventricles and in the septum, equally by 29%. The value was lower than that found after the instrumentation of ramus interventricularis anterior (50%). The results indicate (i) a compromise of the innervation of coronary artery and myocardium after the instrumentation of RC; (ii) the different decrease in density of nerve terminals in the myocardium suggests that majority of adrenergic nerve supply for ventricle myocardium is running along ramus interventricularis anterior.

Animals↗