BACKGROUND: The cardiac electrophysiological characteristics differ significantly among mammalian species or among various disease processes. However, difficulties in the procedures for harvesting and isolating tissue have precluded studies using human cardiac specimens. METHODS: The outward K+ -currents were recorded in human atrial myocytes isolated from patients undergoing open heart surgery. The electrophysiological characteristics of the voltage-dependent outward currents were investigated using a whole-cell patchclamp technique. RESULTS: Using depolarizing step pulses, the transient outward currents were activated within 10 msec, which slowly inactivated thereafter. After inactivation, the sustained components of the outward currents remained for up to 5.0 seconds of depolarizing step pulses. While the inactivating component was almost completely inactivated at potentials >+30 mV, the non-inactivating component showed only 10-15% inactivation. The non-inactivating component was highly sensitive to 4-AP and was inhibited by >80% at a concentration of 0.2 mM, while the inactivating component was inhibited by only 25%. The delayed rectifier potassium currents were not recorded. The ratios of the amplitudes of the inactivating and non-inactivating components varied. CONCLUSION: Two components of the voltage dependent outward K+ currents in human cardiac tissue were identified, which could be separated according to their kinetic and pharmacologic properties.
Atrial Appendage ; Humans* ; Muscle Cells* ; Patch-Clamp Techniques ; Potassium ; Potassium Channels ; Thoracic Surgery

BACKGROUND: Clinical and experimental studies have suggested that brain death may cause hemodynamic, electrocardiographic, functional or histopathologic changes of the heart. METHODS: Brain death was induced by increasing intracranial pressure(ICP) abruptly by intermittent bolus injection of saline(model ) or gradually by continuous infusion of saline(model ) to the epidural catheter in 5 mongrel dogs, respectively. Hemodynamic and biochemical changes during the process of brain death and histopathologic changes of the myocardium were analyzed and compared in two brain death models, and the association of apoptosis was also evaluated. RESULTS: 1) Two predominant subsets of acute contraction band lesion were produced in both brain death models : paradiscal and holocystic contraction band lesions. Both contraction band lesions were more prevalent in brain death model . 2) The frequency of both contraction band lesions was lowest in the epicardial layer and highest in the endocardial layer in both models, but no correlation was observed between the degree of contraction band lesions and ICP, LV maximum +dp/dt or catecholamine levels. There was no statistical difference between any of the LV circumferential blocks and either type of contraction band lesion, and transaxial distribution was not also different in both models. 3) There was no remarkable histopathologic changes in the analysis of major epicardial coronary arteries. Apoptotic cells were suggested in the scattered myocytes in the light microscopy and apoptosis was detected by in situ nick end labeling method. Electron microscopy revealed a condensation of nuclear chromatin and convolution of nuclear membrane in those myocytes. CONCLUSIONS: Myocardial changes due to brain were observed frequently, and few apoptotic cells were found in the brain death heart. Studies on the treatment strategy to minimize damages of myocardial structure and function caused by brain death should be followed in the near future.
Animals ; Apoptosis ; Brain Death* ; Brain* ; Catheters ; Chromatin ; Coronary Vessels ; Dogs ; Electrocardiography ; Heart ; Hemodynamics ; In Situ Nick-End Labeling ; Microscopy ; Microscopy, Electron ; Muscle Cells ; Myocardium* ; Nuclear Envelope

No abstract available.
Bias (Epidemiology) ; Interpersonal Relations ; Stereotyping

Management of cardiac arrhythmias involves antiarrhythmic drugs (AADs), catheter ablation, pacemakers, and implantable defibrillators. The effects of AADs are mediated by blocking various cardiac ion channels, mostly the cardiac sodium, calcium, or potassium channels. A simple classification of AADs based upon the target sites of drug action is useful for clinical application of AADs for common cardiac arrhythmias. Atrioventricular nodal blocking agents are useful for management of tachycardias with the atrioventricular node as a part of the reentrant circuit. Membrane active AADs are used for tachycardias occurring within the atrium or ventricle. Recent large randomized clinical trials have failed to show any beneficial effects of AADs for reducing cardiac mortality in patients with heart failure and at risk of sudden cardiac death or in patients with atrial fibrillation. In spite of these limitations, AAD medication remains an important initial or adjunctive therapy in the management of cardiac arrhythmias.
Anti-Arrhythmia Agents ; Arrhythmias, Cardiac ; Atrial Fibrillation ; Atrioventricular Node ; Calcium ; Catheter Ablation ; Death, Sudden, Cardiac ; Defibrillators, Implantable ; Heart Failure ; Humans ; Ion Channels ; Membranes ; Potassium Channels ; Sodium ; Tachycardia

Regular physical activity provides a variety of health benefits, including improvement in cardiopulmonary or metabolic status, reduction of the risk of coronary artery disease or stroke, prevention of cancer, and decrease in total mortality. Exercise-related cardiac events are occasionally reported during highly competitive sports activity or vigorous exercises. However, the risk of sudden death is extremely low during vigorous exercise, and habitual vigorous exercise actually decreases the risk of sudden death during exercise. The cause of sudden death is ischemic in older subjects (> or =35 years old), while cardiomyopathies or genetic ion channel diseases are important underlying pathology in younger (<35 years old) victims. The subgroup of patients who are particularly at higher risk of exercise-related sudden death may be identified in different ways, such as pre-participation history taking, physical examination and/or supplementary cardiac evaluation. Limitations exist because current diagnostic tools are not sufficient to predict a coronary artery plaque with potential risk of disruption and/or an acute thrombotic occlusion. Proper and cost-effective methods for identification of younger subjects with cardiac structural problems or genetic ion channel diseases are still controversial.
Cardiomyopathies ; Coronary Artery Disease ; Coronary Vessels ; Death, Sudden ; Death, Sudden, Cardiac ; Exercise ; Heart ; Humans ; Insurance Benefits ; Ion Channels ; Motor Activity ; Physical Examination ; Sports ; Stroke

The hypokalemic periodic paralysis is characterized by intermittent falccid paralysis of extremities with spontaneous recovery. It is rarely accompanied by cardiac arrhythmia, especially fatal ventricular tachycardia or torsades de pointes. We observed a 29 year old man, who had suffered from intermittent periodic paralysis and fatal ventricular tachyarrhythmia. He had the first episode of muscle weakness in his low grade of elementary school, which lasted for 20 -30 hours. Similar episodes of muscle weakness occurred 1 -7 times per year, especially after carbohydrate rich food. On admission to emergency room, his chief complaints were generalized weakness and chest tightness, serum potassium level was 1.6mEq/l, and four extremities showed Grade 0 motor weakness. His electrocardiography(ECG) showed Atrioventricular dissociation due to sinus tachycardia and accelerated junctional rhythm, intraventricular conduction distrubance. During intravenous potassium administration, ECG showed sustained ventricular tachycardia and cardiovascular collapse occurred. So we carried out resuscitation and cardioversion. After resuscitation, he recovered from cardovascular collapse and ECG showed sinus tachycardia. But during continuous monitoring ECG showed torsades de pointes with cardiovascular collapse. We carried out resuscitation and defibrillation repeatedly. Serum potassium level was 1.7 - 1.8mEq/L at that time. After successful resuscitation, ECG showed sinus rhythm, and his mental status was fully recovered. After he admitted to intensive care unit, paralytic attack and cardiac arrhythmia did not occurred any more. Serum potassium level was maintained between 3.9 -6.1lmEq/L during his hospital days. He was fully recovered but could not take any medications(e.g. acetazolamide, potassium supplying agent and antiarrhythmic drugs) due to severe gastrointestinal disturbances. During the 30 months of postdischarge period, he experienced three mild paralysis attacks, but they were not accompanied by chest tightness, palpitation or syncope.
Acetazolamide ; Adult ; Arrhythmias, Cardiac* ; Electric Countershock ; Electrocardiography ; Emergency Service, Hospital ; Extremities ; Heart Block ; Humans ; Hypokalemia ; Hypokalemic Periodic Paralysis* ; Intensive Care Units ; Muscle Weakness ; Paralysis ; Potassium ; Resuscitation ; Syncope ; Tachycardia ; Tachycardia, Sinus ; Tachycardia, Ventricular ; Thorax ; Torsades de Pointes

The aconite root has been used in oriental medicine to improve metabolism of debilitated patient and to cure acute dysuria, cardiac weakness, gout, neuralgias and rheumatism. The crude drug "bu-shi" or "cho-oh", which is obtained from the Aconitum roots, contains the potent poisons aconitine, mesaconitine, jesaconitine, and hypaconitine, which are C
Aconitine ; Aconitum* ; Adult ; Alkaloids ; Animal Experimentation ; Arrhythmias, Cardiac* ; Dizziness ; Dysuria ; Gout ; Hemodynamics ; Humans ; Medicine, East Asian Traditional ; Metabolism ; Nausea ; Neuralgia ; Poisons ; Rheumatic Diseases ; Shock* ; Tachycardia ; Tachycardia, Ventricular ; Torsades de Pointes ; Ventricular Fibrillation ; Vomiting

BACKGROUND: Pacing-induced atrial electrical remodeling (AER) is characterized by shortening of atrial effective refractory period (A-ERP) and its altered rate adaptation. In paroxysmal atrial fibrillation (AF), periods of AF occur with interveneing normal sinus rhythm (NSR) when atria recover from the preceding AER. Previous episodes of AF may precondition the atrial myocardium and cause different time course of AER in subsequent episodes of AF. But the influence of the preceding AER on the subsequent AER has not been described. METHODS: Four mongrel dogs were anesthetized with enflurane. After thoracotomy, silicon band with 3 pairs of electrodes was sutured to the lateral wall of the left atrium. Atrial pacing was performed after 2 wks of recovery and autonomic blockade. Pacing protocol consisted of rapid atrial pacing (RAP) at 500 bpm (for 60 min) and recovery in NSR (for 60 min) which was repeated three times. A-ERP was measured every 10 min. The same pacing protocol was repeated after pretreatment with verapamil (0.1 mg/kg/hr). RESULTS: 1) With 60 min of RAP, A-ERP decreased significantly (126+/-6 ms vs. 105+/-7 ms, p<0.005). 2) After cessation of pacing, A-ERP returned to 98% of baseline value in 15 minutes. Recovery from AER occurred faster than AER (78 vs 21 ms/h). 3) After pretreatment with verapamil, RAP decreased A-ERP from 127+/-5 ms to 116+/-5 ms. AER, the reduction in A-ERP, was significantly attenuated by pretreatment with verapamil (deltaERp=17+/-7 vs. 9+/-0.2 %, p<0.05). 4) When RAPs were repeated, AER showed a tendency of acceleration, but it was not statistically significant (deltaERp=22 ms, 24 ms, 28 ms at the end of 60 min pacing for the 1st, 2nd, 3rd pacing). CONCLUSION: RAP induced AER in conscious dog atria and it was reduced by pretreatment with calcium channel blocking agent, verapamil. Upon repeated atrial stimulations, AER did not accelerate or decelerate when the atria recovered from the preceding AER.
Acceleration ; Animals ; Atrial Fibrillation ; Atrial Remodeling* ; Calcium ; Calcium Channels ; Dogs* ; Electrodes ; Enflurane ; Heart Atria ; Myocardium ; Silicones ; Thoracotomy ; Verapamil

OBJECTIVES: Few disciplines in medicine encompasses such wide diagnostic and treatment modalities as cardiology. A traditional text and education system is limited in its efficacy to convey such variety. In order to address this problem, a comprehensive computer-aided education system that compiles and links the current knowledge of cardiovascular diseases is proposed. An availability of such system through CD-ROM and world wide web will contribute undoubtedly to the promotion and betterment of current understandings of cardiology all over the world. METHODS AND RESULTS:1) The information about the cardiovascular diseases has been complied and organized. Multimedia medical information includes text, audio features that allow the users to study actual sounds, and visual aids (slides, real-time demonstration, and schematic illustrations).2) Cardiology education system can be approached according to "Disease module" or "Laboratory test module". One can readily look up the disease of interest and see the results of different tests. Or one can choose the laboratory test or physical examination and study the differences among the diseases. "Self test module" is also available to help user's self assessment of his/her understanding of cardiovascular diseases.3) This cardiology education program is conveniently stored in CD-ROM and can also be accessible through the world wide web (http://med.chungbuk.ac.kr/~mccho/ web-cardiology/alogo.html). CONCLUSION: A multimedia approach for the study of cardiovascular diseases has been developed and is now avaliable in CD-ROM. The same information can be obtained from our home page through the world wide web.
Audiovisual Aids ; Cardiology* ; Cardiovascular Diseases ; CD-ROM ; Education* ; Internet* ; Multimedia ; Physical Examination ; Self-Assessment