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Biomedical subjects

H Pokar

Publications and source records attributed to H Pokar.

18 recordsLinked to original sources
PubMed1991

The effects of aprotinin on hemostatic function during cardiac surgery.

The mechanism of action by which large doses of aprotinin decrease blood loss during cardiac surgery is not completely understood. In a prospective, controlled study, 30 patients undergoing cardiac surgery were given high-dose aprotinin in accordance with a commonly used regimen. Twenty untreated but otherwise comparable patients served as the control group. The effects of aprotinin therapy during cardiopulmonary bypass on coagulation parameters, the kallikrein-kinin system, fibrinolysis, platelet stimulation, and the release of elastase from neutrophils were studied. The fibrinolysis parameters were the only measurements that showed clear and significant differences between the two groups. Aprotinin almost completely inhibited the formation of fibrin and fibrinogen degradation products. It is assumed that inhibition of systemic fibrinolysis and suppression of local fibrinolysis contribute to the hemostatic action of aprotinin. The study did not demonstrate a significant protective effect of aprotinin on platelets. In addition, the dose of aprotinin administered did not affect the kallikrein-kinin system of elastase. Therefore, these data suggest that the previously demonstrated hemostatic effects of aprotinin derive primarily from its antifibrinolytic action.

Aged↗
PubMed1991

Abdominal aortic aneurysm repair after renal transplantation with extracorporeal bypass.

The successful resection of an abdominal aortic aneurysm is presented in a patient who had undergone kidney transplantation 4 years previously. Because the transplanted kidney is more sensitive to ischemia than a normal one, a femoro-femoral bypass with a pump oxygenator was used for perfusion of the transplanted kidney during crossclamping. During the clamping time of 40 minutes kidney perfusion was maintained with a perfusion pressure of 60 to 80 mmHg and the flow was 600 to 1000 ml/min. A collagen-seeded Dacron graft (diameter: 18 mm, length: 12 mm) was interposed. The postoperative course was uncomplicated. We believe that performing the femoro-femoral bypass with a pump oxygenator is an effective and simple method for kidney protection in such operations.

Aorta, Abdominal↗
PubMed1990

[Central nervous system risk factors in heart surgery].

Serious complications involving the central nervous system in the course of cardiac surgical procedures have become rare. Nevertheless, CNS dysfunctions still are observed in a considerable number of patients, exceeding by far the number of those at risk from preoperative neurological hazards. The influence of extracorporeal circulation performance and hypothermia on the physiology of cerebral autoregulation, as well as microembolization events seem to be crucial factors in this context. The resulting regional or global posthypoxic changes in brain metabolism may lead to the manifestation of various neurologic and psychiatric disorders in the postoperative course. These often minor disturbances of CNS function can only be detected regularly and diagnosed correctly in a prospective way by consulting specialists in neurology, psychiatry and psychology, as performed at the Department of Thoracic- and Cardiovascular Surgery of the University Hospital in Hamburg since 1974, and currently in use an international multicenter study. We found postoperative neurological abnormalities in more than 50% of our patients. While irreversible brain damage occurred in only 0.5% of cases, about twothird exhibited transient symptoms that were no longer apparent after 8-10 days postoperatively. Obvious psychopathological symptoms were noted in 10% of cases after surgery, and minor, likewise transient, psychiatric disturbances were seen in up to 50% of patients; 20% suffered from long-lasting psychic problems. The subjective complaints in these cases exceeded the results of objective assessments to a remarkable amount. The discussion focuses on a critical valuation of clinical and supplementary examination techniques and on the potential pathophysiologic mechanisms induced by extracorporal circulation.

Brain Damage, Chronic↗
PubMed1990

[Noncardiac risk factors in heart surgery--the blood coagulation system].

Diagnostics and therapy in coagulation disorders are presented. A special emphasis is given to alterations of blood coagulation in cardiac surgery. No major rule can be defined for this particular field. All disturbances of blood coagulation may become clinically overt in highly variable combinations, thus representing no or high risk to patients conditions. This implies that the actual risk has to be estimated individually for every patient and that the risk of the cardiac disorder has to be considered in view of the risk of the operation plus potential disturbances in coagulation. The latter in order to be assessed appropriately, clearly requires a laboratory specialised in diagnostics of coagulation, as well as a highly experienced coagulation physiologist for decision making. Following this policy, we have not been forced to disagree about extracorporeal circulation for cardiac surgery in most instances. Problems have been confined to patients suffering from various hepatic disorders or from impaired platelet functions.

Blood Coagulation Disorders↗
PubMed1989

[Disorders of fascicular conduction following coronary surgery: etiology and clinical relevance].

Seventy-one consecutive patients undergoing coronary artery bypass grafting (CABG) were studied prospectively. New fascicular conduction defects (FCD) were evident in 51 patients (72%) 1 h after cardioplegic cardiac arrest, in 40 patients (56%) after 2 h, in 29 patients (41%) on the first postoperative day, and in 14 patients (20%) on the seventh postoperative day. Right bundle branch block was the most common type of FCD, followed by left anterior hemiblock. FCD were related to longer aortic cross-clamp time, higher age (p less than 0.025), frequency of wall motion abnormalities (p = 0.033), the number of diseased (p = 0.007) and bypassed vessels (p less than 0.0005), a greater intra- (p = 0.018) and postoperative (p = 0.017) demand for catecholamines, a more complicated postoperative course (p = 0.005), and a longer stay in the intensive care unit (p less than 0.01). Ischemic damage to the conduction system during cardioplegic cardiac arrest appears to be the most likely explanation for new FCD after CABG. Severe coronary heart disease contributes to their development. Hence, adequate myocardial preservation is of crucial importance. FCD are associated with increased perioperative morbidity, according to other studies, also with poorer long-term prognosis, especially in case of a left bundle branch block. In this subset a closer follow-up may be indicated.

Arrhythmias, Cardiac↗
PubMed1979

Hemofiltration during extracorporeal circulation (ECC).

In cardiac surgery hemofiltration can be used: 1. to balance fluids during ECC, especially in long-term perfusion; 2. to carry out open heart procedures in patients with terminal renal insufficiency; 3. to treat acute hyperkalemia. The model of the 12.5 by 4.5 cm DIAFILTER TM and the model of operation are described. The compounds of the ultrafiltrate (UF) are identical with that of plasma water. Particles with a molecular weight of less than 50,000 can pass freely across the filtration membrane. The filtration capacity is 100 cc/min UF (Q blood: 300 cc/min, pressure across the membrane 600 mm Hg and hematokrit (Hkt) 25%). The technical details of operation are explained. Its general use as well as its simplicity is demonstrated in 10 patients.

Adult↗
PubMed1979

Clinical application of cardioplegia in aortic cross-clamping periods longer than 150 minutes.

Out of more than 1000 patients operated upon by means of cardioplegia in profound myocardial hypothermia (15 degrees - 20 degrees C) aortic crossclamping time exceeded 150 min in 26 cases. The average clamping time in this group of patients was 169 +/- 22 min (150 to 227 min). The average duration of the cardioplegic coronary perfusion was 35 +/- 21 min (14 to 99 min). The following procedures were performed. Aneurysmectomy of the ascending thoracic aorta combined with valve replacement (n = 7); valve replacement combined with aorto-coronary bypass procedures (n = 9); multiple valve replacement (n = 3); multiple coronary grafting (n = 6) and one complicated reoperation. Three patients (11.5%) died, none intraoperatively and none as the result of a heart failure connected with the operation.

Adenosine Triphosphate↗
PubMed1978

[Replacement of the thoracic aorta by sealed dacron prostheses (author's transl)].

Dacron prostheses for replacement of the thoracic aorta were sealed with bioadhesive following the Viennese method. Native human fibrinogen was brought to coagulation by adding thrombin. Factor XIII was also added in order to accelerate polymerisation and to reinforce fibrin formation in the presence of thrombin and CaCl2, thus producing a stable thrombus. In order to avoid local fibrinolysis a fast but short-acting as well as a slow but longer-acting antifibrinolytic agent was added. This method was applied in twenty patients. The prostheses remained completely impermeable to blood after resuming circulation in spite of full heparinization. No post-operative haemorrhages from the prostheses were observed.

Aorta, Thoracic↗
PubMed1977

[The regulation of the circulatory system in the early postoperative period after open-heart surgery during physical therapy and orthostatic exercise (author's transl)].

17 patients, who underwent open heart procedures, were examined during and after standardized exercises at the first, second and third postoperative day. At 10 defined time intervals the following parameters were measured: arterial blood pressure, right and left atrial pressure and in the pulmonary artery, arterial and venous blood gases and cardiac output by thermodilution. Oxygen consumption and cardiac index were calculated. The results show that the majority of patients after open heart surgery are well able to adjust to additional work load even early postoperatively.

Adult↗
PubMed1976

[Long-term cardiac arrest by cardioplegic coronary perfusion (author's transl)].

UNLABELLED: The Mg++ aspartate-procaine-cardioplegia has been proven in animal experiments as well as from 1970 til 1975 in more than 1000 open-heart-procedures by a myocardial temperature of 32 degrees C and aortic crossclamping time up to 40 minutes superior to all other known procedures of cardiac preservations. To guarantee a safe myocardial protection of the arrested heart for a remarkable longer period of total ischemia, we further developed the cardioplegic technique in the animal lab, and use it now clinically. PRINCIPLE: The arrest is induced by cardioplegia (Mg++ aspartate-procaine), than the arrested heart is cooled down to 15-20 degrees C by cardioplegic coronary perfusion maintaining the oxidative metabolism. The perfusion is stopped. The begin of ischemia is still under normal ATP-levels and continuous cardioplegia. TECHNIQUE: 1. Crossclamping of the aorta; 2. cardioplegic induced cardiac arrest by Mg++ aspartate-procaine (Kirsch); 3. Surface cooling of the heart; 4. Coronary perfusion by hypothermic cardioplegic solution (8-10 min, flow 80-120 ml/min, perfusion pressure maximal 30 mmHg). Perfusate: O2-saturated, erythrocyte free, 6% hydroxyethyl starch solution added 2 mM Mg++ aspartate, 4 mM procaine, 50 mM Na+, 5 mM K+, 0,5 mM Ca++, 25 mM HCO3-, 10 mM glucose, 200 mM mannitol, 250 mg/l 6-methylprednisolone. RESULTS: 84 patients (29 ACVB; 55 valve replacements); crossclamping time: 71 min (SD 22); total time of ischemia: 57 min (SD 18; max 96, min. 27 min); reperfusion time restoring normal excitation-contraction of the heart: 3 min (SD 2); weaning off bypass: 23 min (SD 14). Hemodynamic 12 h postop.: SO2 venous 76% (SD 6). No sympathicomimetics were used. Only 30% of myocardial ATP is splitted after 120 min of cardiac arrest. Electron microscopic findings show only small, reversible alterations of fine structure.

Adenosine Triphosphate↗
PubMed1975

[Metabolism and ultrastructure of magnesium aspartate-procaine arrested hearts of rabbit and man (author's transl)].

In normothermia, mild, and deep hypothermia the metabolism and the electron microscopic structure were investigated in human and rabbit heart muscle after magnesium aspartate-procaine cardioplegia. In comparison to plain ischaemic arrest splitting of adenine nucleotides and glycogen was significantly reduced in all experiments with the induced cardioplegic arrest. For 40 min at 32 degrees C almost no changes in ultrastructure were seen in heart muscle after induced arrest, while severe and/or irreversible damages were seen in the cell structure of the heart muscle due to plain ischaemic arrest.

Adenine Nucleotides↗
PubMed1975

[Diagnosis, frequency and importance of the "low-output-syndrome" in the postoperative period after mitral valve replacement (author's transl)].

From 1970 until 1975 single mitral valve replacement was carried out in 162 patients using Björk-Shiley disc prostheses. The surgical mortality (within 30 days postoperatively) was 9.3% (n=15). Out of these 15 patients 9 died due to myogenic cardiac insufficiency. 21 patients with "Low-output-Syndrome" due to myogenic insufficiency however survived. The improvement of intraoperative myocardial protection since 1972 (using hypothermia and cardioplegic induced cardiac arrest) reduced the frequency of myogenic cardiac insufficiency to 1%. Unrelated to the above mentioned we saw in 18.5% of all patients after ECC-procedures a temporary "Low-output-Syndrome" after the 3rd postoperative day due to pericardial effusion.

Cardiac Output↗
PubMed1975

[Artificial respiration as treatment of postoperative complications after cardiovascular surgery: indication, technique, results (author's transl)].

From 1972 to 1974 524 patients underwent surgery with extra corporal circulation. 83 (15,8%) patients had to be postoperatively ventilated for a prolonged period or reintubed after a symptomfree interval due to anticipated or manifested complications. 31 (37%) out of these expired. There was no death due to the prolonged ventilation itself, shown by the group, in which the causes for the above treatment were others but respiratory failure or insufficiency. All patients of this group survived. Indications, technique and results are described and discussed.

Germany, West↗
PubMedDate not supplied

Metabolism and fine structure of the Mg++-procaine-arrested perfused heart.

Arrested rabbit hearts were perfused in normothermia for up to two hours by a cardioplegic erythrocyte-containing solution having an increased Mg++-, procaine-, and a reduced NaCl-content. After this time, hearts did not reveal any sign of anoxic or toxic damage in their metabolic pattern, in their ultrastructural picture, and in their functional capacity after reanimation. Despite a small loss in adenine nucleotide content, the ATP/ADP ratio and the PC content were raised. The contents of glycogen and glycolytic intermediates were normal or slightly reduced. After two hours of perfusion mitochondria showed no swelling, their membrane structure was unaltered. The myofibrils were well aggregated. The number of glycogen granules was increased. Hearts were reanimated after two hours of cardioplegia and could be loaded by pressure and volume.

Adenosine Diphosphate↗
PubMedDate not supplied

Metabolism and structure of the magnesium aspartate-procaine-arrested ischaemic heart of rabbit and man.

The fine structure and the content in energy-rich phosphate compounds, glycogen, and metabolites of the Embden-Meyerhoff-pathway in rabbits hearts or human papillary muscles arrested by magnesium aspartate-procaine are investigated in normothermia and mild or deep hypothermia. In all experimental conditions the break-down of adenine nucleotides and glycogen was distinctly retarded in cardioplegia compared to ischaemic arrest. While e.g. an ATP-content of 3.6 mumole/g wet weight was found after 40 min. at 32 degrees C in the magnesium asparate-procaine arrested heart, it dropped down to 1.3 mumole/g in the ischaemically arrested heart. In cardioplegia after 60 min at 15 degrees C the in vivo contents of ATP and glycogen were determined. The rate in metabolic changes in the magnesium aspartate-procaine arrested human papillary muscle was in the range of that recorded in the arrested rabbit heart. The ultrastructural appearance of the cardioplegically arrested heart did not differ from that of the controls after 20 min at 32 degrees C or 120 min at 15 degrees C. In hearts arrested by cardioplegia 40 min at 32 degrees C first signs of ischaemic lesions e.g. mild swelling of mitochondria and few rarefications in mitochondrial matrix were observed. Because of the significantly improved preservation of the fine structure of the heart and retardation of ischaemically provoked changes in cardiac metabolism, the method of inducing heart arrest by cardioplegia should also clinically be given preference to methods of arresting the heart by ischaemia.

Adenosine Triphosphate↗
PubMedDate not supplied

Induced ischemic cardiac arrest. Clinical and experimental results with magnesium-aspartate-procaine solution (Cardioplegin).

The risk of open heart surgery can be lowered by combination of different methods of myocardial protection. 1. Cardioplegia with a potassium free Mg-1-aspartate and Procaine-solution (Cardioplegin). 2. Coronary perfusion after ischemia longer than 35-40 minutes in case of excessive left ventricular hypertrophy or failure. 3. Hypothermia. Surface cooling gives an additional safety if coronary perfusion is not ideal possible in case of multiple coronary stenoses. For patients with this dispositions a continuous coronary perfusion with cardioplegic solution might be advisable, as it was presented by Gercken in his paper. This method was used three times already in human, but is still in an experimental stage.

Animals↗