• The Korean Journal of Physiology and Pharmacology
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• v.4 no.3
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• pp.253-261
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• 2000

Head-out water immersion induces marked increase in the cardiac stroke volume. The present study was undertaken to characterize the stroke volume change by analyzing the aortic blood flow and left ventricular systolic time intervals. Ten men rested on a siting position in the air and in the water at $34.5^{circ}C$ for 30 min each. Their stroke volume, heart rate, ventricular systolic time intervals, and aortic blood flow indices were assessed by impedance cardiography. During immersion, the stroke volume increased 56%, with a slight (4%) decrease in heart rate, thus cardiac output increased ${\sim}50%.$ The slight increase in R-R interval was due to an equivalent increase in the systolic and diastolic time intervals. The ventricular ejection time was 20% increased, and this was mainly due to a decrease in pre-ejection period (28%). The mean arterial pressure increased 5 mmHg, indicating that the cardiac afterload was slightly elevated by immersion. The left ventricular end-diastolic volume index increased 24%, indicating that the cardiac preload was markedly elevated during immersion. The mean velocity and the indices of peak velocity and peak acceleration of aortic blood flow were all increased by ${\sim}30%,$ indicating that the left ventricular contractile force was enhanced by immersion. These results suggest that the increase in stroke volume during immersion is characterized by an increase in ventricular ejection time and aortic blood flow velocity, which may be primarily attributed to the increased cardiac preload and the muscle length-dependent increase in myocardial contractile force.

• The Korean Journal of Nuclear Medicine
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• v.21 no.1
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• pp.33-37
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• 1987

Attenuated end-diastolic and end-systolic left ventricular counts which obtained from cardiac gated blood pool scan were corrected using experimentally calculated attenuation coefficient $(\mu=0.13/cm)$ and depth of center of left ventricle. This method was confirmed to be correct experimentally using phantom balloon. To compare the accuracy of attenuated and attenuation-corrected left ventricular volume measurement, authors studied 10 patients with ischemic heart disease who underwent both gated blood pool scan and X-ray contrast ventriculography within a week. The attenuated and attenuation-corrected left ventricular volume measured by count method correlated with contrast ventriculographic volumes; however, attenuation corrected measurement was correlated more closely.

• Clinical and Experimental Pediatrics
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• v.50 no.11
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• pp.1041-1048
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• 2007

Not a few patients in children and adolescents are suffering from right ventricular (RV) dysfunction resulting from various conditions such as chronic lung disease, left ventricular dysfunction, pulmonary hypertension, or congenital heart defect. The RV is different from the left ventricle in terms of ventricular morphology, myocardial contractile pattern and special vulnerability to the pressure overload. Right ventricular failure (RVF) can be evaluated in terms of decreased RV contractility, RV volume overload, and/or RV pressure overload. The management for RVF starts from clear understanding of the pathophysiology of RVF. In addition to correction of the underlying disease, management of RVF per se is very important. Meticulous control of volume status, inotropic agents, vasopressors, and pulmonary selective vasodilators are the main tools in the management of RVF. The relative importance of each tool depends on the individual clinical status. Medical assist device and surgery can be considered selectively in case of refractory RVF to optimal medical treatment.

• Investigative Magnetic Resonance Imaging
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• v.12 no.1
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• pp.40-48
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• 2008

Purpose : We sought to determine the early change of ventricular geometry and function after concomitant surgeries of modified Dor procedure and mitral valve annuloplasty by using magnetic resonance imaging. Materials and Methods : We enrolled 21 patients with dilated heart failure who underwent modified Dor procedure (n=8), mitral valve annuloplasty (n=6), or both surgeries (n=7). Cine MRI was used to assess left ventricular dimensions and function before and after surgery. We measured the left ventricular end-diastolic and end-systolic volumes and the dimensions of the left ventricular long-axis and short-axis. Left ventricular stroke volume, ejection fraction, and sphericity index were calculated from these measurements. These parameters were analyzed and compared between three different surgery groups to explain the combined effect of the concomitant surgeries. Results : MRI was performed within average $12\;{\pm}\;15$ days (range 1-58 days) before and $38\;{\pm}\;50$ days (range 7- 231 days) after the surgery. The patients who underwent concomitant surgeries had more profound enlargement of left ventricle and decreased contractility prior to surgery than those in the patients who underwent single surgical procedure. Left ventricular end-diastolic volume and endsystolic volume significantly decreased in all patients regardless of surgery type after surgery. Ejection fraction significantly increased only in the patients who got modified Dor procedure without mitral valve annuloplasty (25.4% to 40.7%). Sphericity index increased in patients with modified Dor procedure but decreased in patients with mitral valve annuloplasty (0.65 to 0.78 vs. 0.75 to 0.65). In the patients who underwent concomitant surgeries showed no significant change in sphericity index after surgery. Conclusion : The early change of the left ventricular geometry and function after the concomitant surgeries with modified Dor procedure and mitral valve annuloplasty in patients with dilated heart failure includes a marked reduction in left ventricular volume and in stroke volume. The shape of the left ventricle does not change because the effect of sphericity index decrease from mitral valve annuloplasty is counteracted by the effect of sphericity index increase from modified Dor procedure. Improvement of left ventricular ejection fraction is not the early change after the concomitant surgeries.

• Journal of Chest Surgery
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• v.29 no.8
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• pp.867-874
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• 1996

This study was designed to assess the left ventricular peak systolic pressure/end-systolic volume (PSP/ESV) ratio in predicting symptomatic improvement with valve replacement in patients with aortic regurgitation and enlarged left von'lrlcular volume. We studied 21 patients (15 men and 6 women aged 15 to 60 years) with moderate or severe aortic regur- gitation, no other cardiovascular abnormalities and left ventricular end-systolic volume over 60 m11m2. In this group we assessed the preoperative variables which routinely were measured at cardiac catheterlzation to predict symptomatic improvement with valve replacement. Six months after operation, symptoms were alleviated in 13 patients(62%), and unchanged in 8()8%). By multivariate analysis, the PSP/ESV rati was a strong predictor for functional class 6 months after surgery(p=0.005) and also for change- in functional class prior to an operation to 6 months postoperatively(p=0.0)2). By 6 months after receiving valve replacement, all patients with a ratio over 1. 71 mmHglml/m'were in functional class I or II , in contrast, of those with a ratio < 1.71 mmHg/ml/m2, 40% were in functional class III. The PSP/ESV ratio may help to predict which patients with aortic regurgitation and enlarged left ven- tricular end-systolic volume will have symptomatic improvement with valve replacement.

• Korean Journal of Radiology
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• v.22 no.10
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• pp.1619-1627
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• 2021

Objective: This study used cardiac magnetic resonance imaging (MRI) to compare the characteristics of left ventricular remodeling in patients with primary aldosteronism (PA) with those of patients with essential hypertension (EH) and healthy controls (HCs). Materials and Methods: This prospective study enrolled 35 patients with PA, in addition to 35 age- and sex-matched patients with EH, and 35 age- and sex-matched HCs, all of whom underwent comprehensive clinical and cardiac MRI examinations. The analysis of variance was used to detect the differences in the characteristics of left ventricular remodeling among the three groups. Univariable and multivariable linear regression analyses were used to determine the relationships between left ventricular remodeling and the physiological variables. Results: The left ventricular end-diastolic volume index (EDVi) (mean ± standard deviation [SD]: 85.1 ± 13.0 mL/m² for PA, 75.9 ± 14.3 mL/m² for EH, and 77.3 ± 12.8 mL/m² for HC; p = 0.010), left ventricular end-systolic volume index (ESVi) (mean ± SD: 35.2 ± 9.8 mL/m² for PA, 30.7 ± 8.1 mL/m² for EH, and 29.5 ± 7.0 mL/m² for HC; p = 0.013), left ventricular mass index (mean ± SD: 65.8 ± 16.5 g/m² for PA, 56.9 ± 12.1 g/m² for EH, and 44.1 ± 8.9 g/m² for HC; p < 0.001), and native T1 (mean ± SD: 1224 ± 39 ms for PA, 1201 ± 47 ms for EH, and 1200 ± 44 ms for HC; p = 0.041) values were higher in the PA group compared to the EH and HC groups. Multivariable linear regression demonstrated that log (plasma aldosterone-to-renin ratio) was independently correlated with EDVi and ESVi. Plasma aldosterone was independently correlated with native T1. Conclusion: Patients with PA showed a greater degree of ventricular hypertrophy and enlargement, as well as myocardial fibrosis, compared to those with EH. Cardiac MRI T1 mapping can detect left ventricular myocardial fibrosis in patients with PA.

• Journal of Biomedical Engineering Research
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• v.36 no.5
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• pp.198-203
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• 2015

The purpose of the study is to examine the effects of pacemaker location on cardiac pumping efficacy theoretically. We used a three-dimensional finite element cardiac electromechanical model of canine ventricles with models of the circulatory system. Electrical activation time for normal sinus rhythm and artificial pacing in apex, left ventricular free wall, and right ventricular free wall were obtained from electrophysiological model. We applied the electrical activation time maps to the mechanical contraction model and obtained cardiac mechanical responses such as myocardial contractile ATP consumption, stroke work, stroke volume, ejection fraction, and etc. Among three artificial pacing methods, left ventricle pacing showed best performance in ventricular pumping efficacy.

• Journal of Chest Surgery
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• v.50 no.2
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• pp.71-77
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• 2017

Background: Cardiac computed tomography (CT) has emerged as an alternative to magnetic resonance imaging (MRI) for ventricular volumetry. However, the clinical use of cardiac CT requires external validation. Methods: Both cardiac CT and MRI were performed prior to pulmonary valve implantation (PVI) in 11 patients (median age, 19 years) who had undergone total correction of tetralogy of Fallot during infancy. The simplified contouring method (MRI) and semiautomatic 3-dimensional region-growing method (CT) were used to measure ventricular volumes. Results: All volumetric indices measured by CT and MRI generally correlated well with each other, except for the left ventricular end-systolic volume index (LV-ESVI), which showed the following correlations with the other indices: the right ventricular end-diastolic volume index (RV-EDVI) (r=0.88, p<0.001), the right ventricular end-systolic volume index (RV-ESVI) (r=0.84, p=0.001), the left ventricular end-diastolic volume index (LV-EDVI) (r=0.90, p=0.001), and the LV-ESVI (r=0.55, p=0.079). While the EDVIs measured by CT were significantly larger than those measured by MRI (median RV-EDVI: $197mL/m^2$ vs. $175mL/m^2$, p=0.008; median LV-EDVI: $94mL/m^2$ vs. $92mL/m^2$, p=0.026), no significant differences were found for the RV-ESVI or LV-ESVI. Conclusion: The EDVIs measured by cardiac CT were greater than those measured by MRI, whereas the ESVIs measured by CT and MRI were comparable. The volumetric characteristics of these 2 diagnostic modalities should be taken into account when indications for late PVI after tetralogy of Fallot repair are assessed.

• Journal of Chest Surgery
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• v.21 no.2
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• pp.223-230
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• 1988

Emax, end-systolic pressure-volume relationship, has been established as a new concept which can be representative of ventricular contractility itself since 1970s. Comparing to ejection fraction[EF], Emax is independent of preload and afterload. However Emax has not been proved precisely in non-thoracotomized condition because current methods have limitation in measuring ventricular chamber volume accurately in in viva state. The Dynamic Spatial Reconstructor[DSR], high speed computerized tomography, can measure ventricular chamber volume accurately throughout cardiac cycle in non-thoracotomized state. So Emax and EF of the left ventricle was tried to measure precisely in in vivo condition with DSR. Emax was compared to EF to estimate its ability to evaluate ventricular contractility. 5 mongrel dogs, weighing 15-16kg, were used for measuring Emax and EF of the left ventricle in 3 or 4 different loading conditions using DSR. Emax value in 5 dogs was from 2.62 to 10.49. Each dog has one Emax value regardless of loading conditions. However EF in 5 dogs varies depending on loading conditions. The conclusions are that Emax is useful in in viva state and EF varies depending on loading conditions. So Emax should be tried to use in clinical situation rather than EF because it is always representative of contractility itself regardless loading conditions in in viva state.

• Korean Circulation Journal
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• v.53 no.6
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• pp.406-417
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• 2023

Background and Objectives: Pathophysiological changes of right ventricle (RV) after repair of tetralogy of Fallot (TOF) are coupled with a highly compliant low-pressure pulmonary artery (PA) system. This study aimed to determine whether pulmonary vascular function was associated with RV parameters and exercise capacity, and its impact on RV remodeling after pulmonary valve replacement. Methods: In a total of 48 patients over 18 years of age with repaired TOF, pulmonary arterial elastance (Ea), RV volume data, and RV-PA coupling ratio were calculated and analyzed in relation to exercise capacity. Results: Patients with a low Ea showed a more severe pulmonary regurgitation volume index, greater RV end-diastolic volume index, and greater effective RV stroke volume (p=0.039, p=0.013, and p=0.011, respectively). Patients with a high Ea had lower exercise capacity than those with a low Ea (peak oxygen consumption [peak VO₂] rate: 25.8±7.7 vs. 34.3±5.5 mL/kg/min, respectively, p=0.003), while peak VO₂ was inversely correlated with Ea and mean PA pressure (p=0.004 and p=0.004, respectively). In the univariate analysis, a higher preoperative RV end-diastolic volume index and RV end-systolic volume index, left ventricular end-systolic volume index, and higher RV-PA coupling ratio were risk factors for suboptimal outcomes. Preoperative RV volume and RV-PA coupling ratio reflecting the adaptive PA system response are important factors in optimal postoperative results. Conclusions: We found that PA vascular dysfunction, presenting as elevated Ea in TOF, may contribute to exercise intolerance. However, Ea was inversely correlated with pulmonary regurgitation (PR) severity, which may prevent PR, RV dilatation, and left ventricular dilatation in the absence of significant pulmonary stenosis.