Prospects for prevention of sudden coronary death.
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Coronary Disease↗
Biomedical subjects
M Vrána
Publications and source records attributed to M Vrána.
Dogs at high or low risk of ventricular fibrillation. An experimental study of acute myocardial ischaemia.
In the last 15 years, measurement of the ventricular fibrillation threshold (VFT) after ligation of the coronary artery in anaesthetised dogs has become our standard method for the evaluation of the stabilizing effect of antifibrillation drugs. Analysis of a group of 143 dogs revealed that in 75 animals the VFT 8 minutes after the ligation of the coronary artery dropped to less than 1 mA (high risk group), while in the remaining 68 dogs the decrease was smaller and not below 1 mA (low risk animals). The difference between the groups could be seen already before the ligation of the coronary artery. The high risk animals had a lower VFT and a higher heart rate. The groups also differed in the response to drugs administered 15 minutes after the ligation of the coronary artery. Metipranolol, a liposoluble beta blocker of the beta 1 and 2 cardiac receptors (Trimepranol Spofa 0.3 mg.kg-1 b.w.), increased greatly the VFT in both groups already 8 minutes after the injection of the drug and eliminated the difference between the groups. Flunitrazepam (Rohypnol Hoffmann-La Roche 0.25 mg.kg-1 b.w.) increased the VFT less than metipranolol and the difference between the groups disappeared only 30 minutes after its injection. Celiprolol (Selectol Linz Chemie 3.0 mg.kg-1 b.w.) blocking beta 1 and stimulating beta 2 receptors as well as trimecaine (sodium channel blocker, Mesocain Spofa 3.0 mg.kg-1 b.w.) led only to a small insignificant increase in the VFT and the difference between the groups of dogs remained.(ABSTRACT TRUNCATED AT 250 WORDS)
Acute Disease↗
[The patient after heart transplantation].
The data of the first 100 patients undergoing heart transplantation in the period between January 1984 and May 1993 were analyzed. Of this group, 57 patients are alive. Out of the total of 43 deaths, 14 patients died from graft failure within the first postoperative days, 6 died from surgical complications, 11 from infection, 10 deaths were due to accelerated coronary atherosclerosis, and 2 patients died from tumours. Early mortality rates (within 30 days since surgery) were 37% and 17% in patients operated on between 1984-88 and between 1989-93, respectively. The health condition of heart transplant recipients is affected by side effects of immunosuppressive therapy. Forty per cent of patients re-develop systemic hypertension within the first post-transplantation year. Five years after transplantation, hypertension is detected in 60% of patients. Elevated serum creatinine levels are present in 70% of patients by the end of the first post-transplantation year. In the ensuing period, there is no progression in renal function impairment, which does not require cyclosporin withdrawal and is not associated with the development of hypertension. In the first post-transplantation year, 45% of patients are markedly obese. All patients with overweight and obesity show markedly raised levels of serum cholesterol. Another undesirable effect (mainly due to corticosteroid therapy) is the development of ulcers in 16% of patients. Heart transplantation has become an established method at the Institute for Clinical and Experimental Medicine in Prague. Despite the above pitfalls, heart transplantation substantially prolongs the life of patients and dramatically alters the quality of their life.
Adolescent↗
[Variation in the R-R intervals on the electrocardiogram. A new diagnostic method in cardiology].
Periodic heart rate fluctuation depends on the oscillation of sympathetic and vagal activation of the heart. Periodic retardation and acceleration of heart rate related to respiration and to blood pressure changes can be registered on the ECG as the "variability of R-R intervals". Testing procedures of the variability of R-R intervals at rest, during deep breathing, daily activities, during exercise and other stress tests are described in the paper. For the evaluation of the R-R interval's variability, current statistical methods are used (e.g. mean with standard deviation, variation coefficient, mean beat to beat differences in R-R intervals etc.). Power spectral analysis in the variability of 200-600 successive R-R intervals commonly performed today uses either rapid Fourier transformation or the autoregulation model. The analysis shows high- and low frequency peaks corresponding to the rapid and slow oscillations in heart rate. Evaluation of the R-R interval variability, especially using power spectrum analysis, gave good results in testing drugs, e.g., beta blockers, calcium antagonists and antiarrhythmic drugs. Variability of R-R intervals is reduced in conditions affecting the cardiac autonomous nervous system such as diabetes. It is also decreased in patients with ischaemic heart disease and in those with cardiac failure of different aetiology. The decrease is not an expression of the disease itself: it shows an alteration in neurovegetative tonicity in the particular disease condition. The decreased variability of R-R intervals in patients with ischaemic heart disease has an important prognostic value. The predominance of the sympathetic over the depressed vagal activity signalizes an increased risk of sudden coronary death.
Electrocardiography↗
Heart protection by cardioplegic solutions containing oxyhemoglobin pretreated by carbontetrachloride and freeze-drying with sucrose.
A technologically improved variant of native stroma-free oxyhemoglobin (SFH) pretreated by carbontetrachloride and freeze-drying with 240 mM sucrose were reconstituted in a properly diluted ionic solution to reach the final concentration of 66 g oxyhemoglobin/L, osmolality 280-320 m0sm and pH 7.4. Cardioplegia of isolated rat heart was induced and maintained by this solution without recirculation for 3 h at 20 degrees C prior to heterotopic allo-transplantation of the graft. Evaluation of the survival and performance of each graft after 24 h and extent of tissue necroses indicated that the given standardly produced SFH variant ensured reproducible heart preservation from ischemic and reperfusion injury similarly as did the renown crystalloid cardioplegic solution CUSTODIOL.
Animals↗
A comparison of the protective effect of a modified StTH solution and HTK-B on the energy and functional status of the isolated rat heart.
Using a model of the isolated beating rat heart, the authors compared the protective effect of St. Thomas Hospital cardioplegic solution enriched with glucose and mannitol (StTH-M) and Bretschneider solution (HTK-B). Results showed that, during 120-minute global ischaemia in cardioplegia, StTH-M was able to maintain levels of high-energy phosphates comparable with those found in a group of hearts perfused with HTK-B at 20 degrees C only when the temperature had been decreased to 12-15 degrees C. Under these conditions, repair of metabolic and functional parameters during post-ischaemic perfusion was also similar in both groups.
Animals↗
Analgosedation raises baroreflex sensitivity in acute myocardial ischaemia.
Acute local myocardial ischaemia is associated with a decrease in baroreflex sensitivity while electrical instability (vulnerability) of ventricles increases. Co-administration of a benzodiazepine and a potent analgesic (analgosedation) has been found to raise both baroreflex sensitivity and ventricular fibrillation threshold. Pharmacological modulation of neurovegetative ionization of the heart in the early phase of ischaemia is a promising method for preventing sudden coronary death.
Animals↗
[Directed sympathetic denervation of the heart--an actual therapeutic method or myth?].
Aimed sympathetic denervation of the heart, i. e. bilateral removal of the stellate ganglion Th 1-Th 3 was used in Czechoslovakia since 1981 in eight patients who were followed up for prolonged periods. The patients were operated on account of angina at rest which caused deterioration of the quality of their lives. In case of extensive affection of the coronary arteries surgical treatment was not feasible and pharmacological treatment did not bring relief. At the time of a five-year check up 7 patients survived. All patients reported relief and their efficiency during ergometry improved. Four of the patients worked for several years. The authors discuss whether the above treatment is still justified.
Adult↗
[The effect of mechanical support of the heart on the extent of experimental myocardial necrosis. I].
The authors investigated the influence of mechanical cardiac support with a non-pulsating blood flow on the size of an ischaemic after ligature of the descendent branch of the left coronary artery in the dog. As compared with a control group of experimental animals where mechanical cardiac support was not used, the size of the necrotic focus of the heart muscle diminished by 50% (p less than 0.01). In some of the experimental animals the size of the necrotic focus did not change despite the use of a mechanical cardiac support. Analysis of haemodynamic parameters (assessed and calculated) revealed that for the fate of the necrotic focus of the myocardium the degree of relief (decompression) of the left ventricle is decisive. In complete relief the necrosis diminishes in size.
Animals↗
[Metabolic aspects of hypothermic extracorporeal circulation].
The submitted paper is devoted to some aspects of metabolic and immunity reactions of the organism to extracorporeal circulation. The authors focused attention in particular on a correlation of the whole-body oxygen consumption and the blood sugar level. Surprising findings comprise the rise of the whole-body oxygen consumption which occurs before the tissue temperature rises. As far as toxic oxygen radicals are concerned, their release is individual. It is, however, important that during the perfusion proper the activation of the immune system is suppressed. The course of the extracorporeal circulation was satisfactory from the clinical aspect; despite that it cannot be considered physiological, as also apparent from some biochemical findings.
Blood Glucose↗
[Possibilities of limiting myocardial infarct in an experiment].
A total of 31 dogs were investigated with the aim to evaluate possibilities of pharmacological reduction of ischaemic perfusion damage of the heart muscle. In the experiment two-hour complete ischaemia was used (ligature of the ramus interventricularis anterior) and a subsequent two-hour period of reperfusion. The magnitude of the infarction focus evaluated as the percentage of the ischaemic risk area, using the triphenyltetrazolium method, extended by colour detection of collaterals, was evaluated. Furthermore the authors also evaluated the prevalence of ventricular dysrhythmias in the reperfusion period. In a group of 10 dogs treated by N-acetylcysteine, 100 mg per kg body weight, the authors revealed on comparison with 11 dogs of the control group a diminution of the infarction focus by 32.7%. By addition of Panthenol, 50 mg/kg to N-acetylcysteine in another 10 dogs, a diminution of the infarction by 49% was achieved. The magnitude of the infarction focus was 55.0 +/- 7.0% in the control group, 37.0 +/- 12.6% in dogs treated with N-acetylcysteine (p less than 0.01) and 28.0 +/- 13.3% after administration of N-acetylcysteine and Panthenol (p, as compared with control, again less than 0.01). N-acetylcysteine reduces also significantly the prevalence of ventricular dysrhythmias in the reperfusion period. As compared with the control group this difference is most marked after 60 minutes have elapsed following release of the ligature (p less than 0.001).
Acetylcysteine↗
Prevention of sudden coronary death.
The following results were obtained in an experimental study in the dogs in general pentobarbital anaesthesia: Lidocaine type antiarrhythmics (lidocaine, Xylocaine ASTRA, Ethmozin USSR) administered shortly before artery ligation have a pro-fibrillation effect. This effect is indirectly proportional to the ischaemic focus development. A 3rd-generation beta blocker with intrinsic sympathetic activity (celiprolol, Selectol Chemie-Linz) had the same electrostabilizing effect on the ventricles in the acute phase of ischaemia as a 1st-generation beta blocker (metipranolol, Trimepranol SPOFA). The 3rd-generation blocker, however, stopped short of provoking a drop in the heart rate invariably associated with the 1st-generation beta blocker. The analgesic fentanyl (G. Richter) in combination with benzodiazepine (m,idazolam, Dormicum Hoffmann-La Roche) inducs analgosedation. In this way the dose of the analgetic can be reduced and yet the analgesia and electrostability of the heart remain the same. Due to the lower dose of the analgesic there is a lesser decrease in the heart rate and blood pressure. Analgosedation can be discontinued by administering an antagonist-agonist of benzodiazepines (flumazenil, Anexate Hoffmann-La Roche) or an antagonist of potent analgesics (butorphanol, Beforal SPOFA) without the risk of eliminating, at the same time, the electrostabilizing effect of analgosedation on the ischaemically damaged ventricles of the heart. For the prevention of sudden coronary death due to ventricular fibrillation in the acute phase of local myocardial ischaemia we can, on the basis of our experimental results, recommend analgosedation and the use of beta blockers with intristic sympathetic action. The use of lidocaine antiarrhythmics may lead to a reduction in the electric stability of the heart ventricles the ischaemic focus is developing under a certain "critical" blood level of the antiarrhythmics.
Adrenergic beta-Antagonists↗
Analgosedation-enhanced baroreflex sensitivity in acute local myocardial ischaemia.
In acute local myocardial ischaemia produced in mongrel dogs, the sensitivity of baroreflex decreased as electrical instability (vulnerability) of cardiac ventricles increased. Simultaneous administration of a benzodiazepine and a powerful analgesic (analgosedation) augmented both baroreflex sensitivity and ventricular fibrillation threshold. Modulation of neurovegetative activation of the heart by drugs in the early stage of ischaemia holds promise as a potential technique of sudden coronary death prevention.
Animals↗
[The cardioplegic solution, Plegisol].
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Animals↗
Cardioprotective effects of N-acetylcysteine: the reduction in the extent of infarction and occurrence of reperfusion arrhythmias in the dog.
We have studied the cardioprotective effect of N-acetylcysteine in the dog. In mongrel dogs of either sex, the left anterior descending coronary artery was ligated for a period of 2 hours behind the origin of its first diagonal branch. After this period, dogs in a treated group were administered 100 mg of N-acetylcysteine/kg body weight while a control group remained untreated. This was followed by a 2-hour period of reperfusion. The extent of necrosis was determined using the triphenyltetrazolium method. Presence or absence of collaterals was established at the same time. The incidence of ventricular arrhythmias was monitored throughout the study. Compared with 11 dogs of the control group, 10 dogs treated with N-acetylcysteine showed a decrease of 32.7% in the extent of infarction. The extent of infarction, expressed as the percentage of the left ventricular myocardium at risk, was 55.0 +/- 7.0% in the control group and 37.0 +/- 12.6% in the treated group (P less than 0.01). N-acetylcysteine also statistically significantly decreased the incidence of ventricular arrhythmias over the period of reperfusion. Compared with the control group, the difference was evident as early as the first 5-10 minutes of reperfusion, becoming most pronounced at the 60th minute (P less than 0.001). We conclude that N-acetylcysteine is effective in limiting the extent of infarction and significantly reduces the incidence of reperfusion ventricular arrhythmias.
Acetylcysteine↗
[Electrical instability of the heart ventricles during focal myocardial ischemia].
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Animals↗
[N-acetylcysteine: its effect on myocardial infarct in dogs].
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Acetylcysteine↗
[Therapeutic embolization of the venous bed using Vilan 500 in animal experiments].
The experiment in four dogs verified a suitability of the Czechoslovak preparation Vilan 500, a copolymer of polyvinyl acetate - polyvinyl alcohol in 93% ethanol, for the embolism of venous vascular bed in the percutaneous, transfemoral catheterization way. In all four cases there was a complete occlusion of embolized spermatic or pararenal veins, verified by a control angiography after one hour and after three months. The prepared venous samples were also examined by histology and changes indicating intraluminar thrombotization and subsequent fibrous reconstruction were observed. In view of the results reached it may be concluded that the catheterization technique and the use of Vilan 500 is suitable as an alternative of non-surgical solution of varicocele.
Animals↗