• Journal of information and communication convergence engineering
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• v.19 no.2
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• pp.93-101
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• 2021

Cardiac arrhythmias are common heart diseases and generally cause sudden cardiac death. Electrocardiogram (ECG) is an effective tool that can reveal the electrical activity of the heart and diagnose cardiac arrhythmias. We propose detection of P waves based on QRST cancellation zero-one substitution. After preprocessing, the QRST segment is determined by detecting the Q wave start point and T wave end point separately. The Q wave start point is detected by digital analyses of the QRS complex width, and the T wave end point is detected by computation of an indicator related to the area covered by the T wave curve. Then, we determine whether the sampled value of the signal is in the interval of the QRST segment and substitute zero or one for the value to cancel the QRST segment. Finally, the maximum amplitude is selected as the peak of the P wave in each RR interval of the residual signal. The average detection rate for the QT database was 97.67%.

• Journal of Chest Surgery
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• v.28 no.5
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• pp.437-442
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• 1995

We developed an experimental model of brain death using dogs. Brain death was caused by increasing the intracranial pressure[ICP suddenly by injecting saline to an epidural Foley catheter in five female mongrel dogs[weight, 20-25Kg .Hemodynamic and electrocardiographic changes were evaluated continuously during the process of brain death. 1. Abrupt rise of ICP after each injection of saline followed by a rapid decline to a new steady-state level within 15 minutes and the average volume required to induce brain death was 7.6$\pm$0.8ml.2. Body temperature, heart rate, mean pulmonary arterial pressure, left ventricular[LV enddiastolic pressure and cardiac output was not changed significantly during the process of brain death, but there was an increasing tendency.3. Mean arterial pressure and LV maximum +dP/dt increased significantly at the time of brain death.4. Hemodynamic collapse was developed within 140 minutes after brain death.5. Marked sinus bradycardia followed by junctional rhythm was seen in two dogs and frequent VPB`s with ventricular tachycardia was observed in one dog at the time of brain death. Hyperdynamic state develops and arrhythmia appears frequently at the time of brain death. Studies on the effects of brain death on myocardium and its pathophysiologic mechanism should be followed in the near future.

• Journal of Chest Surgery
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• v.9 no.2
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• pp.198-206
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• 1976

A Total of Forty eight patients underwent open-heart surgery for correction of tetralogy of Fallot at the Seoul National University Hospital from January 1974 to October 1976, with an overall survival rate of 77 per cent. Operative mortality varied according to severity of the lesion, age of the patient, nature of previous surgical treatment and presence or absence of an outflow tract patch across the pulmonary valve ring. Eleven patients died in the early postoperative period and thirty seven patients were discharged from the hospital alive. A patch of the right ventricular outflow tract and pulmonary annulus was required to relieve pulmonic stenosis in 24 patients. There were 10 deaths in this group (42%) as compared to 1 death in the group of 24 patients who were corrected without a patch. Operative mortality was especially higher when an inlay patch was placed across the pulmonary valve ring. This may be related to the possibly greater anatomic severity of these cases and to the longer operating time when a patch was used. The electrocardiogram showed right ventricular hypertrophy in 35 cyanotic patients. Intraventricular conduction was normal in 34 patients before operation. It was normal postoperatively in only 5 of 34 patients in this group who survived surgery. Complete right bundle branch block appeared at operation in 21 patients, and 8 patients developed incomplete right bundle branch block. Major causes of death were progressive cardiac failure (4), Complete atrioventricular dissociation (3), bleeding (2), cardiac tamponade (1), and sudden cardiac arrest (1)

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1665-1668
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• 2008

Arrhythmia causes sudden cardiac death. In the past, there were medical limitations in finding the cause of arrhythmia. As an alternative solution for research of arrhythmia, there have been studies to find the causes of arrhythmia by producing a virtual heart model. Medically, arrhythmia has two main causes: abnormal occurrence of action potential and abnormal conduction of action potential. Based on these, the tachycardia, which is one of the arrhythmia, was manifested and the phenomenon of ventricular fibrillation was numerically analyzed in this study. For this purpose, an electrophysiological model of ventricular cells was implemented, which was subsequently applied to the reaction-diffusion partial differential equation to interpret the macroscopic conduction phenomenon in two-dimensional tissues. The ventricular fibrillation refers to a condition where several irregular waves occur in cardiac tissue, whose generation mechanism is pathologically related to the cardiac tissue.

• Journal of Chest Surgery
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• v.4 no.1
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• pp.43-50
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• 1971

Three patients who sustained penetrating stab wound of the heart have been treated successfully by emergency thoracotomy in the Department of Thoracic Surgery, Chonnam University Hospital. There were two knife and one glass wound. The location of the injury were all on the right ventricle, but in one patient, it was penetrated to ventricular septum. All patients were in shock with a systolic pressure under 60 mmHg when admitted to the emergency room. In one of the three patients, blood pressure was not detectable and subsequently cardiac arrest. Two patients required immediate thoracotomy because of intrathoracic hemorrhage and increased pericardial tamponade and the other one required prompt thoracotomy because of sudden onset of cardiac arrest. There were no death postoperatively. Two patients are living without any complication in 4 years and 4 weeks after operation. One who had penetrating wound to ventricular septum, turned to cardiac decompensation, but he is living now in 4$\frac{1}{2}$ years after operation. Exploratory thoracotomy should be performed immediately in all the patients in whom a penetrating wound of the heart or pericardial tamponade following a penetrating wound of the chest wall is suspected.

• Clinical and Experimental Pediatrics
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• v.46 no.10
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• pp.996-1002
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• 2003

Purpose : In Rett syndrome patients, the incidence of sudden death is greater than that of the general population, and cardiac electrical instability including fatal cardiac arrhythmia is a main suspected cause. In this study, we are going to find out the possible cause of the higher risk of sudden death in Rett patients by the evaluation of heart rate variability, a marker of cardiac autonomic activity and corrected QT intervals. Methods : Diagnosis of Rett syndrome was made by molecular genetic study of Rett syndrome (MECP2 gene) or clinical diagnostic criteria of Rett syndrome. Heart rate variability and corrected QT intervals were measured by 24 h-Holter study in 12 Rett patients, and in 30 age-matched healthy children with chief complaints of chest pain or suspected heart murmurs. The were compared with the normal age-matched control. Results : Patients with total Rett syndrome, classic Rett syndrome, and Rett variants had significantly lower heart rate variability(especially rMSSD)(P<0.05) and longer corrected QT intervals than age-matched healthy children(P<0.05). Sympathovagal balance expressed by the ratio of high to low frequency(LF/HF ratio) also showed statistically significant differences between the three groups considered(P<0.05). Conclusion : A significant reduction of heart rate variability, a marker of autonomic disarray, suggests a possible explanation of cardiac dysfunction in sudden death associated with Rett syndrome.

• Proceedings of the Korean Biophysical Society Conference
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• 1999.06a
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• pp.64-64
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• 1999

Amitriptyline has been known to induce QT prolongation and ventricular arrhythmias such as torsades de pointes which causes sudden death. We studied the effects of amitriptyline on the human ether-a-go-go-related gene (HERG) channel expressed in Xenopus oocytes.(omitted)

• Journal of Chest Surgery
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• v.27 no.10
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• pp.838-845
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• 1994

From April, 1982 to December, 1992, multiple valve replacement was performed in 100 patients. Mitral and aortic valve replacement were done in 86 patients, 9 underwent mitral and tricuspid valve replacement, 4 patients underwent triple valve replacement and 1 patient underwent aortic and tricuspid valve replacement. Of the valve implanted, 100 were St. Jude, 64 Duromedics, 19 Carpentier-Edwards, 13 Bj rk-Shiley, 6 Ionescu-Shiley, and 2 Medronics.The hospital mortality rate was 15%[15 patients] and the late mortality rate was 7%[7 patients], the mortality rate was high in early operative period but decreased with time[20% at 1986, 18.2% at 1987, 9.5% at 1988, 11.1% at 1989, 12.5% at 1990, 11.8% at 1991, 0% at 1992]. The causes of death were low cardiac output in 8, sudden death in 3, CHF in 3, bleeding in 2, cerebral thromboembolism in 1, leukemia in 1, multiorgan failure in 1 and so on. The actuarial survival rate excluding operative death was 73% at 10 years.

• Journal of Chest Surgery
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• v.22 no.6
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• pp.970-979
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• 1989

From April 1982 to December, 1988, multiple valve replacement was performed in 49 patients. Mitral and aortic valve replacement were done in 42 patients, 4 underwent mitral and tricuspid valve replacement and 3 patients underwent triple valve replacement. Of the valve implanted, 50 were Duromedics, 21 St. Jude, 13 Bjork-Shiley, 9 Carpentier-Edwards, 6 Ionescu-Shiley, and 2 Medtronic. The hospital mortality rate was 28.5 % [14 patients] and the late mortality rate was 6.1 % [3 patients], the mortality rate was high in early operative period but decreased with time. [20% at 1986, 18.2 % at 1987, 9.5% at 1988] The causes of death were low cardiac output in 8, congestive heart failure in 2, multiple organ failure in 1, LV rupture in 1, intracerebral hemorrhage in 1 and sudden death in l. The actuarial survival rate excluding operative death was 77% at 7 years.

• Journal of Chest Surgery
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• v.28 no.12
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• pp.1113-1121
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• 1995

From August, 1986 to December, 1993, mitral valve replacement was performed in 178 patients. Of the valve implanted, 114 were St.Jude Medical, 47 Duromedics, 16 Carpenter-Edward and 1 Ionesc-Shiley. The hospital mortality rate was 2.8%[5 patients and the late mortality rate was 7.5%[13 patients . The causes of hospital death were LV rupture in 1, renal failure in 1, cardiac tamponade in 1, valve malfunction in 1 and hypoxic brain damage in 1. The causes of late death were sudden death in 6, congestive heart failure in 4, brain ischemic injury in 3. Follow-up was done on 155 surviving patients : mean follow-up period was 50.94$\pm$8.04 months. The actual survival rate was 88.2% at 8 years. We concluded, therefore, that good clinical results could be achieved with mitral valve replacement in mid-term follow-up, and long-term follow-up is also necessary.