• The Korean Journal of Pharmacology
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• v.21 no.2
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• pp.119-127
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• 1985

The renal function is under regulatory influence of the central nervous system, mainly through activation of sympathetic nerve to the kidney, and it was recently reported that clonidine, an agonist to ${\alpha}_2$-adrenoceptors, induces diuresis and natriuresis when injected directly into a lateral ventricle of the rabbit brain (i.c.v.). This study was undertaken, therefore, to obtain further information as to the role of the central ${\alpha}_2$-adrenoceptors in regulating renal function, by observing the effects of i.c.v. yohimbine, a specific antagonist of adrenoceptors of ${\alpha}_2$-type, on the rabbit renal function, and to elucidate the mechanism involved in it. With 10 ${\mu}g/kg$ i.c.v. of yohimbine sodium excretion transiently increased along with increasing tendency of urine flow, renal plasma flow and glomerular filtration rate. These responses decreased with increasing doses. With 100 and 300 ${\mu}g/kg$ i.c.v. marked antidiuresis and antinatriuresis as well as profound decreases of renal perfusion and glomerular filtration were noted. Systemic blood pressure transiently increased. In reserpinized rabbits, 100 ${\mu}g/kg$ yohimbine i.c.v. did not produce any significant changes in urine flow, sodium excretion as well as in renal hemodynamics. The pressor response was also abolished. In preparations in which one kidney was denervated and the other left intact as control, i.c.v. yohimbine elicited typical antidiuretic antinatriuretic response in the innervated control kidney, whereas the denervated experimental kidney responded with marked diuresis and increases in excretory rates of sodium and potassium and in osmolar clearance in spite of absence of increased filtration and perfusion . Systemic blood pressure responded as in the normal rabbits. These observations indicate that i.c.v. yohimbine affects renal function in dual ways in opposite directions, the first being the antidiuretic antinatriuretic effects which results from decreased renal perfusion and glomerular filtration due to sympathetic activation and which is predominantly expressed in the normal rabbits, and the second less apparent effect being the diuretic and natriuretic action which is not mediated by nerve pathway but brought about by some humoral mechanism and which is effected by decreased sodium reabsorption in the tubules, possibly of the proximal portion.

• Journal of Chest Surgery
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• v.30 no.4
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• pp.378-382
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• 1997

To evaulate the effectiveness and risk factors for shunt failure of the Blalock-Taussig shunt in neonates, we analyzed the 21 neonates who were undergone Blalok-Taussig shunt operation at Dong-A University Hospital from December 1991 to Feburary 1996. We evaluated operative mortality, patency of the shunt. and distortion of pulmonary artery. We also determined the risk factors for the shunt failure. Age at operation was from 1 day to 30 days(mean 11.7 days). We ghts were 2.4 to 4.5kg(mean 3.1 kg). The underlying lesions included severe tetralogy of Fallot with pulmonary stenosls or atresia(N=11) and single ventricle varieties with. pulmonary stenosis or atresia(N=10). Prostaglandin El was given in 13 neonates prior to operation. The mean preoperative(prior to prostaglandin El therapy) and postoperative arterial oxygen tension were 30.1 mmHg and 46.3 mmHg respectively(P(0.01). The shunt was performed through a left thoracotomy in 11 patients and through a right thoracotomy In 10. A 5 mm graft was used in 15 patients and a 4 mm graft in 6 patients. The incidence of early shunt occlusion was 9.5%(2 patients). The hospital mortality was 9.5%(2 patients with early shunt occlusion). Univariate analysis revealed that body weight of 2.6 kg or less(p=0.021), pulmonary artery size of 3mm or less(p=0.008), and 4 mm graft (p=0.021) were risk factors predictive of early shunt failure. The patency rate of the shunt in hospital survivors was 100% at mean ollow-up of ll.3 months(There was not death or reoperation related to shunt failure). 10 patients were catheterized during postoperative follow-up. There was no significant distorsion of pulmonary artery. So we concluded that the modified Blalock-Taussig shunt in neonates was excellent in the hospital survivors.

• The Korean Journal of Nuclear Medicine
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• v.30 no.1
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• pp.112-117
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• 1996

Objective: Standard stress/rest Tc-99m MIBI and T1-201 myocardial perfusion study have some limitations such as stress/rest image overlap for Tc-99m-MIBI, low energy for T1-201 and long period of study time for two separate studies. Separate acquisition rest T1-201/stress Tc-99m MIBI dual isotope study is a potentially efficient myocardial perfusion imaging protocol that combines the high resolution of Tc-99m for stress perfusion assessment and T1-201 for viability assessment. This study assessed the usefulness and diagnostic accuracy for this new approach. Methods: We tried to evaluate sensitivity and specificity of dual isotope separate acquisition protocol in 67 patients. Immediately after resting T1-201 SPECT data was acquired, dipyridamole stress Tc-99m MIBI myocardial perfusion study was performed. Visual analysis was carried out qualitatively with 0 to 3 scoring system for 17 segments of left ventricle in the reconstructed horizontal long axis and short axis slices. Results: Total study was completed within 3 hours. In angiographic correlation, dual isotope SPECT demonstrated high sensitivity(85%) and in a small group of patients, high specificity was also observed (100%). Conclusion: Combined thallium-201/stress Tc-99m MIBI SPECT displayed similiar diagnostic accuracy to protocol using stress/rest Tc-99m MIBI SPECT. This protocol was completed in shorter period than the previous protocols and therefore enhance laboratory throughput and patients convenience.

• The Korean Journal of Nuclear Medicine
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• v.28 no.3
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• pp.317-325
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• 1994

The accuracy of dipyridamole stress/rest $^{99m}Tc$-MIBI myocardial imaging for detection of ischemia depends on reproducible image interpretation. To evaluate the reproducibility of visual assessment, agreement in interpretation among two independent observers, blind-ed to clinical data, was evaluated in SPECT images of 131 patients (94 males, 38 females; mean age $58{\pm}7yr$) with suspected coronary artery disease who underwent both dipyridamole stress/rest $^{99m}Tc$-MIBI myocardial SPECT and coronary angiography. The left ventricle was divided into twenty-nine segments in stress and rest SPECT images and each segment was visually graded according to a five-point scale (segmental score : 0=normal, 1=equivocal, 2=mild decrease, 3=severe decrease and 4=absent uptake). Overall concordance of segmental scoring between the two observers was 80%. The Pear-son's correlation coefficient (r) of the segmental scores for stress and rest images were 0.67 and 0.65, respectively, while the difference in score between the two images showed a correlation of 0.45 (all p<0.001). Agreement between two observers in final SPECT diagnosis as absence or presence of disease was 93%. The degree of agreement in segmental scoring showed no difference between patients with or without agreement as to the presence of disease. Therefore it appeared that cases with inconcordant diagnosis between the 2 observers were mainly due to a difference in individual threshold for interpretating the significance of a particular decreased uptake area rather than to a difference in perceiving the degree of the hypoactivity Thus, establishment of individual optimum thresholds in visual interpretation of myocardial SPECT may be helpful to improve reproducibility and accuracy of scan diagnosis.

• The Korean Journal of Pharmacology
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• v.11 no.2
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• pp.29-40
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• 1975

1. Sites of the cardioaccelerating action of nicotine, DMPP, McN-A-343, AHR-602, tyramine, angiotensin and neostigmine were investigated in spinal rabbits. 2. The cardioaccelerating action of the above substances was substantially weak in reserpine-pretreated rabbits. The accelerating action was scarcely observed after propranolol administration. 3. Tetrodotoxin and guanethidine did not affect the cardioacceleration due to nicotine, DMPP, tyramine and isoproterenol, but they markedly weakened that due to McN-A-343, AHR-602, angiotensin and neostigmine. 4. Chlorisondamine blocked the cardioacceleration by nicotine and DMPP; atropine that by McN-A-343 and AHR-602. 5. Appropriate doses of isoproterenol, nicotine, DMPP, McN-A-343, tyramine, angiotensin and neostigmine, when administered into the right auricle, produced almost the same degree of cadia acceleration as when they were given to the right ear vein. AHR-602 did not produce significant cardioacceleration through this route. 6. Nicotine, DMPP and neostigmine when injected into the right auricle produced marked cardioacceleration, whereas they produced little action when injected into the left ventricle. Isoproterenol and tyramine produced more marked effect by the intraauricular route than the intraventricular one. 7. McN-A-343, AHR-602 and angiotensin produced more marked cardioacceleration by the intraventricular administration than the intraauricular one. The intraventricular AHR-602 produced marked cardioacceleration. 8. It is inferred that the sites of cardioaccelerating action of nicotine, DMPP, and tyramine will be either the terminals of the adrenergic nerves or the extraneuronal stores of norepinephrine and that of McN-A-343, AHR-602, angiotensin and neostigmine will be the adrenergic neurons in the heart. The sites on which nicotine, DMPP, tyramine and neostigmine will act are chiefly distributed in the auricular tissues and those on which McN-A-343, AHR-602, and angiotensin act chiefly in the ventricular tissues.

• Journal of Chest Surgery
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• v.38 no.2 s.247
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• pp.123-131
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• 2005

Background: The number of elderly patients undergoing coronary artery bypass grafting (CABG) is increasing. Elderly patients are at increased risk for a variety of perioperative complications and mortality. We identified determinants of operative complications and mortality in elderly patients undergoing CABG. Material and Method: Between January 1995 and July 2003, 91 patients older than 75 years underwent isolated CABG at Asan Medical Center. There were 67 men and 24 women with mean age of $77.0\pm2.4$ years. Thirty clinical or hemodynamic variables hypothesized as predictors of operative mortality were evaluated. Result: CABG was performed under emergency conditions in 5 patients. The internal thoracic artery was used in 85 patients and 10 patients received both internal thoracic arteries. The mean number of distal anastomosis was 3.7 per patient. Operative mortality was $3.3\%$. Twenty-two patients had at least one major postoperative complication. Low cardiac output syndrome was the most common complication, followed by reoperation for bleeding, pulmonary dysfunction, perioperative myocardial infarction, stroke, acute renal failure, ventricular arrhythmia, upper gastrointestinal bleeding, infection, and delayed sternal closure. None were the predictors of mortality. Renal failure, peripheral vascular disease, emergency operation, recent myocardial infarction, congestive heart failure, New York Heart Association (HYHA) class III or IV, Canadian Cardiovascular Society (CCS) angina scale III or IV, and low left ventricle ejection fraction below $40\%$ were univariate predictors of overall complications. Actuarial probability of survival was $94.9\%,\;89.8\%,\;and\;83.5\%$ at postoperative 1, 3 and 5 years respectively. During the follow-up period $93.3\%$ of patients were in NYHA class I, or II and $91.1\%$ were free from angina. Conclusion: Although operative complication is increased, CABG can be performed with an acceptable operative mortality and excellent late results in patients older than 75 years.

• Korean Journal of Radiology
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• v.23 no.3
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• pp.298-307
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• 2022

Objective: This study aimed to evaluate the effect of implementing the consensus statement from the Asian Society of Cardiovascular Imaging-Practical Tutorial 2020 (ASCI-PT 2020) on the reliability of cardiac MR with late gadolinium enhancement (CMR-LGE) myocardial viability scoring between observers in the context of ischemic cardiomyopathy. Materials and Methods: A total of 17 cardiovascular imaging experts from five different countries evaluated CMR obtained in 26 patients (male:female, 23:3; median age [interquartile range], 55.5 years [50-61.8]) with ischemic cardiomyopathy. For LGE scoring, based on the 17 segments, the extent of LGE in each segment was graded using a five-point scoring system ranging from 0 to 4 before and after exposure according to the consensus statement. All scoring was performed via web-based review. Scores for slices, vascular territories, and total scores were obtained as the sum of the relevant segmental scores. Interobserver reliability for segment scores was assessed using Fleiss' kappa, while the intraclass correlation coefficient (ICC) was used for slice score, vascular territory score, and total score. Inter-observer agreement was assessed using the limits of agreement from the mean (LoA). Results: Interobserver reliability (Fleiss' kappa) in each segment ranged 0.242-0.662 before the consensus and increased to 0.301-0.774 after the consensus. The interobserver reliability (ICC) for each slice, each vascular territory, and total score increased after the consensus (slice, 0.728-0.805 and 0.849-0.884; vascular territory, 0.756-0.902 and 0.852-0.941; total score, 0.847 and 0.913, before and after implementing the consensus statement, respectively. Interobserver agreement in scoring also improved with the implementation of the consensus for all slices, vascular territories, and total score. The LoA for the total score narrowed from ± 10.36 points to ± 7.12 points. Conclusion: The interobserver reliability and agreement for CMR-LGE scoring for ischemic cardiomyopathy improved when following guidance from the ASCI-PT 2020 consensus statement.

• Journal of Chest Surgery
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• v.36 no.12
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• pp.929-936
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• 2003

We analysed the surgical outcomes of immediate reoperations after mitral valve repair. Material and Method: Eighteen patients who underwent immediate reoperation for failed mitral valve repair from April 1995 through July 2001 were reviewed retrospectively. There were 13 female patients. The mitral valve disease was regurgitation (MR) in 12 patients, stenosis (MS) in 3, and mixed lesion in 3. The etiologies of the valve disease were rheumatic in 9 patients, degenerative in 8, and endocarditis in 1. The causes of reoperation was residual MR in 13 patients, residual MS in 4, and rupture of left ventricle in 1. Fourteen patients had rerepair for residual mitral lesions (77.8%) and four underwent replacement. Result: There was no early death. After mean follow-vp of 33 months, there was one late death. Echocardiography revealed no or grade 1 of MR (64.3%) in 9 patients and no or mild MS in 11 patients (78,6%). Reoperation was done in one patient. The cumulative survival and freedom from valve-related reoperation at 6 years were 94% and 90%, respectively. The cumulative freedom from recurrent MR and MS at 4 years were 56% and 44%, respectively. Conclusion: This study suggests that immediate reoperation for failed mitral valve repair offers good early and intermediate survival, and mitral valve rerepair can be successfully performed in most of patients. However, because mitral rerepair have high failure rate, especially in rheumatic valve disease, adequate selections of valvuloplasty technique and indication are important to reduce the failure rate of mitral rerepair.

• The Korean Journal of Nuclear Medicine
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• v.38 no.6
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• pp.486-491
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• 2004

Purpose: factor analysis and independent component analysis (ICA) has been used for handling dynamic image sequences. Theoretical advantages of a newly suggested ICA method, ensemble ICA, leaded us to consider applying this method to the analysis of dynamic myocardial $H_2^{15}O$ PET data. In this study, we quantified patients' blood flow using the ensemble ICA method. Materials and Methods: Twenty subjects underwent $H_2^{15}O$ PET scans using ECAT EXACT 47 scanner and myocardial perfusion SPECT using Vertex scanner. After transmission scanning, dynamic emission scans were initiated simultaneously with the injection of $555{\sim}740$ MBq $H_2^{15}O$. Hidden independent components can be extracted from the observed mixed data (PET image) by means of ICA algorithms. Ensemble learning is a variational Bayesian method that provides an analytical approximation to the parameter posterior using a tractable distribution. Variational approximation forms a lower bound on the ensemble likelihood and the maximization of the lower bound is achieved through minimizing the Kullback-Leibler divergence between the true posterior and the variational posterior. In this study, posterior pdf was approximated by a rectified Gaussian distribution to incorporate non-negativity constraint, which is suitable to dynamic images in nuclear medicine. Blood flow was measured in 9 regions - apex, four areas in mid wall, and four areas in base wall. Myocardial perfusion SPECT score and angiography results were compared with the regional blood flow. Results: Major cardiac components were separated successfully by the ensemble ICA method and blood flow could be estimated in 15 among 20 patients. Mean myocardial blood flow was $1.2{\pm}0.40$ ml/min/g in rest, $1.85{\pm}1.12$ ml/min/g in stress state. Blood flow values obtained by an operator in two different occasion were highly correlated (r=0.99). In myocardium component image, the image contrast between left ventricle and myocardium was 1:2.7 in average. Perfusion reserve was significantly different between the regions with and without stenosis detected by the coronary angiography (P<0.01). In 66 segment with stenosis confirmed by angiography, the segments with reversible perfusion decrease in perfusion SPECT showed lower perfusion reserve values in $H_2^{15}O$ PET. Conclusions: Myocardial blood flow could be estimated using an ICA method with ensemble learning. We suggest that the ensemble ICA incorporating non-negative constraint is a feasible method to handle dynamic image sequence obtained by the nuclear medicine techniques.