Lege Artis Medicinae

[Pathophysiology of myocardial ischemia and reperfusion]

PAPP Zoltán1, ÉDES István1

JUNE 01, 2000

Lege Artis Medicinae - 2000;10(06)

[Complete and long lasting loss of coronary circulation results in myocardial cell death (ischemic necrosis). Short lasting ischemia (few minutes) is well tolerated and it may bring certain protection against recurrent ischemia (ischemic preconditioning). Contractile force promptly diminishes following the onset of ischemia and the changes in the intracellular ATP or Ca2+ concentration do not explain this phenomenon. With the progression of ischemia, myocardial relaxation ceases and hypertonic muscle activation appears (ischemic contracture). During myocardial reperfusion following short-term ischemia, arrhythmias often develop and pump function is regularly depressed transiently (myocardial stunning). Permanent reduction in coronary blood supply results in sustained ventricular dysfunction (hibernation). It has been established, that pathologic processes leading to ischemic injury are distinct from those of reperfusion injury. Cellular events are complicated (Ca2+-overload, free radical injuries, activation of proteolytic processes, energy loss, membrane damage, hypercontracture, etc.), and complete understanding of the background of ischemic/reperfusion disorders is still awaited. ]

AFFILIATIONS

  1. Debreceni Egyetem, Orvos- és Egészségtudományi Centrum, Orvostudományi Kar, Kardiológiai Klinika, Debrecen

COMMENTS

0 comments

Further articles in this publication

Lege Artis Medicinae

[Infectiosus diseases - Past, present, future]

SZALKA András

[The complex interactions between microorganisms and humans include the well known, traditional infectious diseases and also the symbiotic relationship with the human endogenous normal flora. Forty years ago everybody was convinced that medicine would soon be able to eradicate most of the infectious diseases. Perception of victory over infectious diseases has been blunted in recent years by nosocomial infections and by the new and re-emerging diseases. The spectrum of infectious diseases is expanding and many of those once thought conquered are increasing in numbers. Moreover, the problems of infection are present in all aspects of medicine and with the field turning more and more complex its challenge for practitioners has become increasingly demanding. It is now clear, that at the dawn of the new millennium infectious disease remains the number one killer in the world. ]

Lege Artis Medicinae

[Practical aspects of screening for microalbuminuria in diabetic patients]

JERMENDY György, FARKAS Klára, NÁDAS Judit, DARÓCZY Atilla, PÉTERFALI Éva

[INTRODUCTION - The importance of measuring microalbuminuria is well established, however, controversy still exists regarding the type of urine specimen to be used for detecting early renal impairment of diabetic patients. PATIENTS AND METHODS – To evaluate practical aspects, albumin concentration and albumin to creatinine ratio of first void urine samples as well as urinary albumin excretion in timed specimens were determined by immunoturbidimetric method 3 times within 3 weeks in 192 adult diabetic patients (136 men, 56 women; type 1/type 2: 90/102; age: 51.4=10.8 years; duration of diabetes: 15.3+9.1 years; body mass index: 27.9+4.6 kg/m2; HbA1c: 8.5+1.5 %; actual blood pressure: 13814/82+8 mmHg; serum creatinine: 94+20 umol/l; x+SD). RESULTS - According to the urinary albumin excretion values, one third of patients (31.2%-30.7%-34.4%) were normoalbuminuric (<30 mg/24 hours), more than half of the patients (55.8%-57.3%-53.6%) proved to be microalbuminuric (30-300 mg/24 hours), while the remaining group of patients (13.0%-12.0%–12.0%) was macroalbuminuric (>300 mg/24 hours). Comparing the results of successive measurements good correlation was found between the same laboratory values (urinary albumin excretion: K=0.64; K=0.67; urinary albumin concentration: K=0.60; K=0.62; albumin to creatinine ratio: K=0.54; K=0.61; first vs. second and second vs. third measurements, respectively). The percentage of patients being in the same range of albuminuria (i.e. normo-, micro-or macroalbuminuria) at successive measurements was 79.7-81.2% with urinary albumin excretion values, 77.1-77.6% with urinary albumin concentration and 74.5-78.6% with albumin to creatinine ratio. Good correlations were found between urinary albumin excretion and urinary albumin concentration (K=0.54; 0.54; 0.57) and nearly the same correlations were observed between urinary albumin excretion and albumin to creatinine ratio (K=0.49; 0.47;0.54) at different series. Using values of urinary albumin excretion for comparison at all measurements, 79.3% sensitivity and 69.5% specifity were found for urinary albumin concentration whereas 74.6% sensitivity and 68.8% specifity were documented for albumin to creatinine ratio. CONCLUSION - Beside the standard measurement of urinary albumin excretion in timed urine samples, the use of the more convenient morning urinary spot collection could also provide useful results (urinary albumin concentration or albumin to creatinine ratio) for detecting early renal involvement in diabetic patients. ]

Lege Artis Medicinae

[Hypertension And BPH Intervention Trial]

MATOS Lajos

Lege Artis Medicinae

[Postnatal development of the human hippocampal formation]

SERESS László

[Jean Piaget's theory suggests that cognitive development proceeds in discrete steps. The first is the sensorimotor period that happens in the first two years of life. In recent years it became clear, that it is necessary to have an intact and mature hippocampus for adequate memory formation, both in experimental animals and humans. In the present study, the morphological development of the human hip pocampus was correlated with the developmental changes of intellectual development. Our results suggest that neuronal cell formation of the human hippocampus terminates several weeks before birth. In the dentate gyrus, a small number (less than 1%) of granule cells are still formed around birth. Immature granule cells migrate through the hilar region to their final position in the granule cell layer during the first six postnatal months. Light microscope studies of individual neurons indicate that connections between granule cells and their target neurons are not yet formed at birth. Such connections develop during the third postnatal year. If the development of the synaptic connections is damaged in experimental animals, the hippocampal function will be permanently impaired. Newborns may have basic synaptic circuits for memory formation, but the postnatal morphological changes suggest the significant modification of the hippocampal circuits happening continuously from the newborn age until late childhood. These changes may cause the phenomenon of the "infantile amnesia". ]

Lege Artis Medicinae

[Scientific Browser]

All articles in the issue

Related contents

Lege Artis Medicinae

[Stress adaptation of te myocardium in the presence of systemic disorders]

FERDINANDY Péter

[Effective therapeutic strategies for protecting the ischemic myocardium are much sought after. Ischemic heart disease in humans is a complex disorder often associated with other systemic diseases such as dyslipidemia, hypertension and diabetes mellitus exerting multiple biochemical effects on the myocardium. Ischemic preconditioning of myocardium is a well-described adaptive response where brief exposure to ischemia markedly enhances the ability of the heart to tolerate a subsequent ischemic episode. The underlying cellular and molecular mechanisms of pre conditioning have been extensively investigated in the hope of identifying new therapeutic approaches for the protection of the ischemic myocardium. However, most studies have been undertaken in animal models where ischemia was applied in the absence of other diseases, therefore the clinical relevance is questionable. In this article, we review different ways how systemic disease could modify preconditioning response and we also emphasise the importance of further pre-clinical studies for the specific examination of preconditioning in the presence of other complicating disease. ]

Lege Artis Medicinae

[Ischemic preconditioning of the myocardium; The clinical experience]

SIMON Kornél, SZELIER András

[The authors give an account of the pathomechanism of ischemic preconditioning. This complex adaptation is achieved by the joint compliance of perfusion, metabolism, function and morphology. The process is triggered by repeated ischemic attacks when transmitter substances are liberated during ischemia, as seen in previous experiments. These modulators are the possible substrates of pharmacologic preconditioning. The principle of parallel treatment of perfusion and metabolism is reviewed with its clinical importance. The clinical manifestations of ischemic preconditioning and the pharmacological approach to mimic preconditioning in the clinical setting are discussed. It is established, that the self-repair mechanisms of the organism can not prevent grave macroangiopathy with its consequences. Persisting ischemia during preconditioning signals the necessity of urgent clinical examinations and effective treatment. By saving time with myocardial adaptation, there will be good chance for the patient to have a successful revascularisation intervention.]

Lege Artis Medicinae

[Antianginal effects of verapamil]

KÉKES Ede

[Verapamil is the prototype of the calcium antagonists. Administration of the drug produces a beneficial antianginal effect due to de creased preload and afterload through vasodilation without marked reflex tachycardia and also due to a special influence on myocardium (negative inotropy and positive lusitropy) in all forms of ischaemic heart disease. Verapamil is also a strong coronary dilator drug. Verapamil was given in doses of 240–360 mg daily. The investigators concluded that exercise tolerance increased and the number of anginal attacks and nitroglycerin (sublingual) consumption decreased. The rate-pressure product is reduced on verapamil. Its cardio protective effect on myocardial structure is still an object of discussion.]