• 대한의용생체공학회:의공학회지
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• 제18권1호
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• pp.37-44
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• 1997

In this paper, the power spectral analysis of heart rate variability(HRV) was performed to evaluate effects of orthostatic stress with head-up tiIt on autonomic nervous system(ANS) for 25 healthy male subjects(age : 24 $\pm$ 5 yr.) and a new method was proposed to assess the autonomic balance. The ECG and respiration signals were recorded at tiIt angles of $0^{\circ}$, $45^{\circ}$, $90^{\circ}$and $0^{\circ}$ successively for 10 minutes per each stage under the condition of frequency controlled respiration(0.25Hz). Heat rate(HR) gradually increased ils the angle increased Similarly, according to the increment of angle, normalized low frequency component(0.05-0.15Hz) gradually increased, whereas normalized high frequency component (0.20-0.30Hz) was reduce4 From these results it is speculated that orthostatic stress head-up tiLt, results in the prevalence of sympathetic tone in autonomic balance with the increment of sympathetic tone and the decrement of parasympathetic tone, which seems to meanthat autonomic nervous system plays a major role in compensating for disturbances of cardiovascular system due to it.

• Annals of Clinical Neurophysiology
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• 제1권1호
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• pp.64-69
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• 1999

Background : Syncope was defined as transient loss of consciousness and postural tone. The mechanisms of changes in cerebral hemodynamics during syncope have not been fully evaluated. Transcranial Doppler Ultrasonography can continuously monitor the changes in cerebral hemodynamics during head-up tilt (HUT). TCD could reveal the different patterns of changes in cerebral hemodynamics during syncope. Syncope without hypotension or bradycardia could be detected by TCD. We investigated the changes in cerebral blood flow velocity during HUT using TCD in 33 patients with a history of recurrent syncope or presyncope of unknown origin. Methods & Results : The positive responses were defined as presyncope or syncope with hypotension, bradycardia, or both. During HUT without isoproterenol infusion, there were a $86{\pm}23%$ drop in DV and a $41{\pm}34%$ drop in SV in 5 patients with positive reponses, and mean changes in those were less than 10% in patients with negative reponses (p=.00, p=.00). During HUT with isoproterenol infusion, TCD showed a $80{\pm}18%$ drop in diastolic velocity in 14 patients with positive reponses, and a $47{\pm}10%$ drop in that in patients with negative reponses (p=.00), however the change in systolic velocity did not differ. TCD showed three patterns during positive responses; loss of all flow, loss of end diastolic flow, and a decrease in diastolic velocity. Loss of consciousness occurred in the patients with loss of all flow or end-diastolic flow during positive reponses. Conclusions : TCD shows different patterns of changes in cerebral hemodynamics during HUT. TCD can be used to investigate the pathophysiology of neurocardiogenic syncope.

• Clinical and Experimental Pediatrics
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• 제64권11호
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• pp.582-587
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• 2021

Background: Syncope is a common problem in children and adolescents. However, a large proportion of syncope cases have no underlying cause. Purpose: This study aimed to identify the factors affecting the severity of syncope using tissue Doppler imaging (TDI). Methods: This retrospective study included 61 children and adolescents with syncope who underwent echocardiography. The head-up-tilt test (HUT) was performed when there was a more severe syncopal event. We compared the echocardiographic findings between the execute HUT and nonexecute HUT, negative HUT result and positive HUT result, and normal electrocardiogram (ECG) and abnormal ECG groups. Data were analyzed using an unpaired t test post hoc analysis. Results: In the execute and nonexecute HUT groups, the odds ratios were 0.55 for medial E/E' (P=0.040) and 0.64 for lateral E/E' (P=0.049). Comparison of the results of the decreased, normal, and increased groups for lateral E/E' revealed a significant difference in the execution HUT and nonexecute HUT groups (overall, P=0.004; decreased vs. increased, P=0.003; normal vs. increased, P=0.050). Conclusion: Medial E/E' and lateral E/E' were decreased in patients with severe syncopal events. These findings suggest that the presence of left ventricular diastolic deterioration may cause hypoperfusion even in the absence of organic causes and, consequently, increase syncope severity and frequency. The TDI measured by echocardiography can be used as an index to predict syncope recurrence and/or severity.

• Annals of Clinical Neurophysiology
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• 제12권2호
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• pp.61-65
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• 2010

Background: Orthostatic hypotension (OH) refers to a fall in systolic blood pressure (BP) of 20 mmHg or more, or in diastolic BP of 10 mm Hg or more within 3 minutes of standing up. The head-up tilt test (HUT) is the most useful, but potentially invasive test for the diagnosis of OH. The purpose of this study was to identify the usefulness of spontaneous baroreflex sensitivity (sBRS). Methods: Ninety one patients with orthostatic intolerance, in whom the HUT data were available, were included in the study. Patients were classified into HUT-positive (group I) and HUT-negative (group II) group. Twenty five healthy volunteers served as normal controls, and were designated as group III. In all subjects, beat-to-beat BP and heart rate were recorded using BeatScope 1.1a. We collected the 50 sBRS data in each patient in a supine position. The average value of one to ten of 50 sBRS data was defined as sBRS10, one to twenty as sBRS20, one to thirty as sBRS 30, one to forty as sBRS 40, and one to fifty as sBRS 50. Differences in sBRS10 and sBRS50 levels were statistically analyzed and compared between groups I, II, and III. Results: No significant difference in the sBRS50 level was found between Groups II and III. sBRS50 was significantly lower in Group I than in Groups II and III (p<0.05), and the same pattern of differences was observed for sBRS40, sBRS30, sBRS20, and sBRS10. Conclusions: Patients with OH showed significantly lower sBRS levels than HUT-negative patients or normal controls. Our study implies that a supine-position sBRS would provide additional diagnostic information for OH.

• The Korean Journal of Physiology
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• 제19권2호
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• pp.139-153
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• 1985

기립 및 도립의 체위면화가 두부 및 하지의 혈액순환계에 미치는 영향을 관찰하고, atropine의 정주에 의한 부교감신경의 차단이 체위변화에 대한 심맥관계의 내성을 증가시키는 지를 보기위하여 개를 경사대에 수평위로 고정하여 수동적으로 기립 및 도립위로 체위를 변화시키고, 각 체위에서 10분간 유지시켜 경동맥, 외경정맥, 고동맥 및 고정맥의 분시 혈류량, 분시 심박수 및 분시 호흡수, 그리고 혈액의 pH, $PCO_2$, $PO_2$ 및 Hct를 측정하였다. 다시 수평위에서 atropine 0.5mg을 1회 정주한 후 위의 실험과정을 반복하여 시행하고 atropine투여전과 비교 관찰하였던 바 다음과 같은 결과를 얻었다. 기립시 두부 및 하지 동정맥혈의 분시 혈류량은 감소하였고, 특히 두부로 가는 혈류량의 감소가 더 컸으나, atropine의 투여는 경동맥의 분시 혈류량의 감소를 억제하였다. 도립시 두부 및 하지의 분시 혈류량은 유의한 변화를 보이지 않았고, 개체에 따라 변화양상도 다르게 나타났다. atropine의 투여는 투여전에 비하여 유의한 차이를 보이지 않았다. 분시 심박수는 기립 및 도립시 모두 증가하였다. atropine의 투여는 수평위에서 분시 심박수는 투여전 보다 증가하나, 체위변화에 의한 분시 심박수의 증가를 경감시켰다. 분시 호흡수는 개체에 따라 변화양상에 차이가 있으나, 대체로 기립시는 감소하고 도립시는 증가하였다. atropine의 투여는 기립 및 도립시 다 같이 분시 호흡수의 변화를 억제하였다. 혈액소견은 기립시 정맥철의 pH 및 $PO_2$는 감소하였고, $PCO_2$는 증가하나 동맥혈의 $PCO_2$는 감소하였다. 도립시 동정맥혈의 소견은 수평위에 비해 별 변화가 없었으며 , atropine의 투여후도 기립 및 도립시 모두에서 투여전에 비하러 유의한 변하는 없었다. Hct는 기립 및 도립시 증가하였으며 atropine투여에 의한 변화는 관찰할 수 없었다. 이상에서와 같이 atropine의 투여는 기립시 두부로 가는 혈류량을 증가시키며, 기립 및 도립시 발생할 수 있는 분시 심박수의 과도한 증가를 억제함으로서 체위변화에 대한 심맥관계의 내성을 증가시키는데 어느정도 효과가 있다고 하겠다.

• The Korean Journal of Physiology
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• 제7권1호
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• pp.13-21
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• 1973

An attempt was made to study circulatory and respiratory responses to the passive tilt. Anesthetized dogs were tilted from horizontal to upright $(+90^{\circ})$ and head down $(-90^{\circ})$ position. The arterial blood pressure was decreased in the upright position and was decreased slightly in the head down position comparing to that in the horizontal position. Cardiac index also decreased in the both upright and head down positions. The total systemic vascular resistance was slightly increased in the upright position and was markedly increased in the head down position. The mean pulmonary arterial pressure was significantly decreased in the both upright and head down positions. The total pulmonary vascular resistance was decreased in the both upright and head down positions. Oxygen consumption was slightly decreased in the upright position, whereas it was slightly increased in the head down position. The A-V $O_2$ difference (vol. %) was slightly increased in the upright position and increased in the head down position. From the above results, process of the circulatory compensation to the gravity in the Passive tilting test was discussed. Neuronal cardiovascular regulation to the gravity and tile adaptation of capacitance vessles to hydrostatic stress and oxygen consumption concerning anoxic endurance of the brain were also discussed.

• Clinical and Experimental Pediatrics
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• 제52권7호
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• pp.798-803
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• 2009

목 적 : 실신은 소아와 청소년들에게 흔히 발생되는 증상으로 혈관 미주신경성 실신이 가장 흔한 형태다. 이 연구의 목적은 원인불명의 실신 및 그와 유사한 증상으로 내원한 소아청소년기 환자들에게 기립 경사 검사(head-up tilt test, HUT)의 반응과 진단적 가치를 검토해 보고자 하였다. 방 법 : 2003년 5월부터 2008년 3월까지 전북대학교병원에 실신 및 실신 전 증상을 주소로 HUT를 하고 임상적으로 혈관 미주신경성 실신이 의심되는 160명(남 82명, 여 78명, 7-20세)을 대상으로 임상 양상 및 HUT 결과와 그 반응에 대해 의무기록을 통하여 후향적 조사를 시행하였다. HUT는 70도 경사에서 45분간 시행하였으며 일부는 isoproterenol 0.5-1.0 ug/min 주사를 이용하였으며 이 환아들을 소아군(7-12세, 39명, $10.59{\pm}1.60$세), 청소년군(13-20세, 121명, $15.93{\pm}2.28$세)으로 분류하여 두 군 간의 HUT 양성률과 그 반응유형을 비교해 보았다. 결 과 : 대상 환아 160명 중에서 양성반응인 환아는 92명(57.5%)이었고, 남녀 비는 차이가 없었다. 양성 반응은 혼합형이 70례로 제일 흔한 반응이었고, 혈관억제형이 12례, 무수축을 동반하지 않은 심장억제형이 6례, 무수축을 동반한 심장억제형이 4례이었다. 실신의 원인을 규명하는데 HUT를 비롯하여 혈액흉부 방사선 촬영, 심전도와 24시간 holter 검사 및 운동부하검사, 뇌파 검사, 뇌 단층촬영과 뇌 자기공명검사, 심초음파 검사 등이 시행되었다. 또한 연령대에 따른 HUT의 양성 반응률 비교는 소아군 43.6% (17/39), 청소년군 62% (75/121)이었고, 혼합형 반응이 소아 군에서 15명(38.4%)에서 청소년군 55명(45.0%)으로 청소년군이 더 높은 양성률을 보였으나 두 그룹간의 통계학적으로 의미 있는 차이는 없었다. 결 론 : HUT는 혈관 미주신경성 실신이 의심되는 병력과 진찰 소견이 정상인 소아에서 여러 다른 검사 방법에 우선하여 시행함으로써 실신의 원인을 규명하는데 유용하다.

• Annals of Clinical Neurophysiology
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• 제25권1호
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• pp.27-31
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• 2023

Orthostatic dizziness is feeling dizzy or lightheaded when standing up. Hemodynamic orthostatic dizziness can be caused by autonomic dysfunction such as orthostatic hypotension or postural tachycardia syndrome. The interpretation of the autonomic function test results in patients with orthostatic dizziness is crucial for diagnosing and managing the underlying condition. The head-up tilt and Valsalva tests are especially important for evaluating adrenergic function in patients with hemodynamic orthostatic dizziness. However, it is important to note that autonomic function tests do not cover the entire diagnostic process, since their findings need to be considered along with the detailed history and physical examination results of the patient because various differential diagnoses exist for orthostatic dizziness. Ensuring appropriate treatment by interpreting the autonomic function test results can help to determine the improvement of and prevents falls from orthostatic dizziness.

• Annals of Clinical Neurophysiology
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• 제21권1호
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• pp.30-35
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• 2019

Background: Postural tachycardia syndrome (POTS) refers to the presence of orthostatic intolerance symptoms associated with a heart rate increment of greater than 30 beats/min, usually up to 120 beats/min, on head-up tilt test. Symptoms related to POTS are usually light-headedness, palpitations and tremor, but syncope can also occur. The pathophysiology of POTS is heterogeneous and its prognosis is uncertain. Methods: We prospectively evaluated patients who met the criteria for POTS, at baseline and follow-up, using composite autonomic symptom scores and autonomic tests to assess the autonomic function. We compared the clinical and autonomic test results between baseline and follow-up. Results: Sixty-eight patients met the inclusion criteria for POTS and forty-five patients were ultimately followed up for at least 1 year after baseline. The patients were predominantly young females (84%), with a mean age of 21 years. Most patients showed improved orthostatic symptoms and more than a quarter of patients had no longer met the criteria for POTS at follow-up. Conclusions: Most patients had a benign outcome in that they could resume their daily activities without great limitations. Our results demonstrated a relatively favorable prognosis in most patients with POTS.

• Clinical and Experimental Pediatrics
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• 제65권1호
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• pp.47-52
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• 2022

Background: An adequate large-scale pediatric cohort based on nationwide administrative data is lacking in Korea. Purpose: This study aimed to differentiate patients with VVS by autonomic dysfunction severity using the composite autonomic severity score (CASS) and compare the clinical manifestations and prognosis between patient subgroups. Methods: We retrospectively reviewed the medical records of 66 VVS patients divided into 3 groups by CASS. To compare the differences between these groups, we analyzed VVS type, triggers, prodromal symptoms, management of syncope, and prognosis between patients with mild versus moderate autonomic dysfunction. Results: Of our 66 patients with VVS, 41 had mild autonomic dysfunction (62.1%) and 25 had moderate autonomic dysfunction (37.9%). We found no significant intergroup differences in age, sex, inducible factor (P=0.172), prodromal symptoms, laboratory findings, head-up tilt test, type of syncope, or prognosis (P=0.154). Conclusion: We found no evidence that autonomic dysfunction degree is affected by VVS characteristics, test findings, parameters, or prognosis; therefore, no further evaluations are needed to classify autonomic dysfunction severity.