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Biomedical subjects

Jae K Oh

Publications and source records attributed to Jae K Oh.

At least 19 recordsLinked to original sources

Simple risk models to predict surgical mortality in acute type A aortic dissection: the International Registry of Acute Aortic Dissection score.

BACKGROUND: Surgical mortality for acute type A aortic dissection is frequently related to preoperative clinical conditions. We report a predictive score to identify risk of death that may be helpful to assist surgeons who are considering whether to proceed with surgical correction in the case of patients in extreme clinical risk. METHODS: Surgical outcome of 682 patients enrolled in the International Registry of Acute Aortic Dissection from 1996 to 2003 was analyzed. Two different models were used. The initial model included only preoperative variables such as demographics, history, symptoms, signs, and diagnostic methods (model 1). The second model also tested intraoperative hemodynamic and surgical variables (model 2). A bedside risk prediction tool to predict operative mortality in individual patients was developed. RESULTS: The overall in-hospital surgical mortality was 23.9%. Independent preoperative predictors of mortality in model 1 were age greater than 70 years, prior cardiac surgery, hypotension (systolic blood pressure less than 100 mm Hg) or shock at presentation, migrating pain, cardiac tamponade, any pulse deficit, and electrocardiogram with findings of myocardial ischemia or infarction. In model 2, other predictors of surgical death were intraoperative hypotension, a right ventricle dysfunction at surgery, and a necessity to perform coronary revascularization. An independent predictor for favorable surgical outcome was right hemiarch replacement. CONCLUSIONS: Surgery in unstable patients with acute type A aortic dissection can be highly unsuccessful. The International Registry of Acute Aortic Dissection risk models predict in-hospital mortality using a multivariable risk prediction tool, useful for surgeons and patients as they consider their surgical risk and the pros and cons of embarking on high-risk surgery.

Acute Disease↗

The effect of 18 h of simulated high altitude on left ventricular function.

High altitude produces increased pulmonary capillary pressure by hypoxia induced pulmonary vasoconstriction. It is also possible that hypoxia results in mildly elevated left ventricular (LV) filling pressures that may contribute to the elevated capillary pressures. This study investigates the impact of simulated high altitude on global and regional echocardiographic measures of LV performance and filling pressure. Seventeen healthy individuals underwent transthoracic echocardiography, including tissue Doppler of the septal mitral annulus and basal segments before and after an 18-h overnight stay in a high altitude simulation tent with a FiO(2) of 12%, simulating an altitude of approximately 4,000 m above sea level. In simulated high altitude, the ratio of early transmitral flow velocity to early myocardial relaxation velocity increased 22%, P < 0.001, and the Index of Myocardial Performance increased 30%, P < 0.01 due to an 58% increase in the isovolumic relaxation time (IVRT), P < 0.001. Simulated high altitude leads to a reduction in LV performance with an accompanying increase in markers of LV filling pressure. The significant changes in filling pattern and IVRT in the setting of normal and unchanged systolic function, indicates that hypoxia induces mild diastolic dysfunction in young healthy individuals.

Acclimatization↗

Mitral valve surgery in heart failure: insights from the Acorn Clinical Trial.

OBJECTIVE: The study objective was to evaluate in a prospective, randomized, multicenter trial the safety and efficacy of mitral valve surgery with and without the CorCap cardiac support device (Acorn Cardiovascular, St Paul, Minn) in patients with New York Heart Association Class II to IV heart failure. BACKGROUND: Although mitral valve surgery has been performed successfully in patients with heart failure, the safety and long-term efficacy have not been established in a multicenter prospective trial. Cardiac support devices that reduce ventricular wall stress and promote beneficial reverse remodeling have been proposed as a new treatment option as a stand-alone procedure and as an adjunct to mitral valve surgery. METHODS: A subgroup of 193 patients were enrolled in the mitral valve repair or replacement stratum of the Acorn Clinical Trial; 102 patients were randomized to the mitral valve surgery alone group (control) and 91 patients were randomized to mitral valve surgery with implantation of the CorCap cardiac support device. Patients were followed for a median duration of 22.9 months. RESULTS: For the entire mitral valve surgery group, the 30-day operative mortality rate was only 1.6% at 30 days. Mitral surgery was associated with progressive reductions in left ventricle end-diastolic volume, left ventricle end-systolic volume, and left ventricular mass, and increases in left ventricle ejection fraction and sphericity index, all consistent with reverse remodeling. Recurrence of clinically significant mitral regurgitation was uncommon. Quality of life, exercise performance, and New York Heart Association functional class were all improved. Finally, the addition of the CorCap cardiac support device led to greater decreases in left ventricular end-diastolic volume and left ventricular end-systolic volume, a more elliptical shape, and a trend for a reduction in major cardiac procedures and improvement in quality of life compared with mitral surgery alone. CONCLUSIONS: These findings suggest that there is clear benefit to the surgical elimination of mitral regurgitation and that there is additional benefit with the CorCap cardiac support device. Given the improvement in left ventricle structure and function, along with a low mortality rate, physicians should strongly consider offering mitral valve surgery in combination with the CorCap cardiac support device to patients with heart failure who are on an optimal medical regimen.

Cardiac Surgical Procedures↗

Outcome of patients with low ejection fraction undergoing coronary artery bypass grafting: renal function and mortality after 3.8 years.

BACKGROUND: There are few data regarding medium-term outcome of coronary artery bypass grafting (CABG) in patients with severe left ventricular (LV) systolic dysfunction, particularly in the modern era, and even less assessing preoperative factors that might identify patients at highest risk. METHODS AND RESULTS: Three hundred seventy-nine consecutive patients with LV ejection fraction < or = 35%, who underwent isolated first CABG between 1995 and 1999 were studied. Potential preoperative and perioperative predictors of outcome were recorded and patients followed-up for a median of 3.8 years. The primary study end-point was all-cause mortality. The 30-day, 1-year, and 3-year survival rates were 94.5%, 88%, and 81%, respectively. The independent predictors of mortality were preoperative estimated glomerular filtration rate (hazard ratio [HR], 0.98; 95% confidence interval [CI], 0.97 to 0.99 per mL/min/1.73 m2; P<0.001) and age (HR, 1.03; 95% CI, 1.01 to 1.06 per year; P=0.005). CONCLUSIONS: Patients with significant LV systolic dysfunction undergoing isolated CABG using contemporary techniques have a good medium-term survival. Renal dysfunction is the strongest independent predictor of mortality.

Aged↗

Left atrial size: physiologic determinants and clinical applications.

Left atrial (LA) enlargement has been proposed as a barometer of diastolic burden and a predictor of common cardiovascular outcomes such as atrial fibrillation, stroke, congestive heart failure, and cardiovascular death. It has been shown that advancing age alone does not independently contribute to LA enlargement, and the impact of gender on LA volume can largely be accounted for by the differences in body surface area between men and women. Therefore, enlargement of the left atrium reflects remodeling associated with pathophysiologic processes. In this review, we discuss the normal size and phasic function of the left atrium. Further, we outline the clinically important aspects and pitfalls of evaluating LA size, and the methods for assessing LA function using echocardiography. Finally, we review the determinants of LA size and remodeling, and we describe the evidence regarding the prognostic value of LA size. The use of LA volume for risk stratification is an evolving science. More data are required with respect to the natural history of LA remodeling in disease, the degree of LA modifiability with therapy, and whether regression of LA size translates into improved cardiovascular outcomes.

Atrial Function↗

Transient midventricular ballooning syndrome: a new variant.

We describe a new variant of transient left ventricular (LV) ballooning in North American Caucasian patients in which only the midventricle is affected. The patients described in this case series initially presented with emotional or physical stress and had similarities to transient apical ballooning syndrome; however, this variant is unique in that the transient ballooning involves the midventricle with hypercontractility of the apical and basal segments. The presentation, clinical features, and transient nature of the reported cases in this series are similar to transient LV apical ballooning and suggest a shared pathophysiologic etiology. Sparing of the apical segment with involvement of midventricle only supports etiologies not related to an epicardial coronary artery distribution. Although the pathophysiologic mechanism of the transient ventricular ballooning syndromes and other cases of catecholamine-associated transient ventricular dysfunction are not well understood, the emergence of this new variant raises further questions in the understanding of the "brain-heart" relationship.

Aged↗

Relation of left atrial volume to B-type natriuretic peptide levels in patients with stable chronic heart failure.

This study assessed the relation between B-type natriuretic peptide (BNP) and echocardiographic indexes of left ventricular (LV) filling pressure in 53 patients with stable heart failure and without significant valvular dysfunction. Left atrial volume indexed to body surface area (LAVi), an indicator of chronic LV filling pressure, was correlated with BNP (r = 0.692, p <0.001) and was the strongest independent predictor of elevated levels in this cohort. LAVi was also the best predictor of BNP >or=100 pg/ml, with an area under the receiver-operating characteristic curve of 0.85 (95% confidence interval 0.74 to 0.96, p <0.001). Using the optimal cutoff of >31 ml/m(2), LAVi had a sensitivity of 92% and a specificity of 65% for BNP >or=100 pg/ml. Patients with LAVi >31 ml/m(2) had a median BNP of 122 pg/ml, compared with 21 pg/ml in patients with LAVi <or=31 ml/m(2) (p <0.001). These findings suggest that in patients with stable heart failure, BNP levels are related to chronic LV filling pressures. This may help explain the relatively modest correlation between BNP and acute measures of LV filling and the heterogeneity in BNP levels in patients with stable heart failure.

Aged↗

Diastolic heart failure can be diagnosed by comprehensive two-dimensional and Doppler echocardiography.

There are many myocardial and non-myocardial conditions that cause heart failure with normal left ventricular ejection fraction (LVEF). Among them, diastolic heart failure (heart failure due to diastolic dysfunction) is the most common cause of heart failure with normal LVEF. Diastolic heart failure easily can be diagnosed by comprehensive two-dimensional and Doppler echocardiography, which can demonstrate abnormal myocardial relaxation, decreased compliance, and increased filling pressure in the setting of normal LV dimensions and preserved LVEF. Therefore, diastolic heart failure should always be considered when LVEF is normal on two-dimensional echocardiography in patients with clinical evidence of heart failure. The diagnosis can be confirmed if Doppler echocardiography and myocardial tissue imaging provide evidence for impaired myocardial relaxation (i.e., decreased longitudinal velocity of the mitral annulus during early diastole and decreased propagation velocity mitral inflow), decreased compliance (shortened mitral A-wave duration and mitral deceleration time), and increased filling pressure (shortened isovolumic relaxation time and an increased ratio between early diastolic mitral and mitral annular velocities). Early identification of diastolic dysfunction in asymptomatic patients by the use of echocardiography may provide an opportunity to manage the underlying etiology to prevent progression to diastolic heart failure.

Blood Flow Velocity↗

Wall motion score index and ejection fraction for risk stratification after acute myocardial infarction.

BACKGROUND: The prognostic importance of regional systolic function, as assessed by wall motion score index (WMSI), compared with global function, as assessed by left ventricular ejection fraction (LVEF), has not been assessed in large populations after acute myocardial infarction. METHODS: Echocardiograms, including the assessment of WMSI and LVEF, were performed in 767 patients with acute myocardial infarction at a median of 1 day (25th and 75th percentiles 0-2 days) after admission. Patients were followed for a median of 19 months (range 12-28 months). Cox proportional hazards models were constructed for the primary study end point (all-cause mortality) and for a secondary end point (hospitalization for congestive heart failure). RESULTS: During follow-up (median 40 months; range 32-50 months), 216 patients died and 54 patients were hospitalized for congestive heart failure. By univariate analysis, both LVEF (P < .0001) and WMSI (P < .0001) were powerful predictors of all-cause mortality. By a forward conditional Cox model, WMSI proved to be an independent predictor of death (hazard ratio 1.15 per 0.2-unit increase, 95% CI 1.10-1.21, P < .0001). When WMSI was included in the model, LVEF did not provide additional prognostic information (P = .77). Wall motion score index also proved to be an independent predictor of hospitalization for congestive heart failure (hazard ratio 1.21 per 0.2-unit increase, 95% CI 1.07-1.37, P = .002), whereas LVEF did not (P = .56). CONCLUSION: Both LVEF and WMSI provide powerful prognostic information after acute myocardial infarction; however, the predictive power of WMSI is greater.

Aged↗

Accuracy, reproducibility, and comparability of Doppler tissue imaging by two high-end ultrasound systems.

INTRODUCTION: Doppler tissue imaging is a new technology for quantitative evaluation of myocardial motion and contractility, and is available in several ultrasound systems. This study evaluates the comparability, accuracy, and reproducibility of measurements of velocity, strain rate, and strain by two high-end ultrasound systems. METHODS: Accuracy was assessed by imaging a tissue-mimicking gelatin phantom, and the comparability of measurements in the right ventricular free wall and interventricular septum was assessed in 20 healthy participants. Reproducibility was evaluated by repeated recordings in vitro and in a random subset of patients. RESULTS: In vitro, a high degree of accuracy was found in both systems, with one system measuring slightly lower values than the reference values (mean difference 0.35 +/- 0.18 cm/s, P < .001). Values higher than the reference values were measured by both systems for strain and strain rate. In vivo, no systematic differences in measured velocities, strain rate, and strain were found; however, wide limits of agreement were seen for strain and strain rate. Measurements of tissue velocity, strain, and strain rate were well reproducible, nevertheless wide variation was found in both systems (coefficient of variation = 9%-19%). CONCLUSION: For clinical purposes, both systems have sufficient accuracy for measurements of tissue velocity. The variation in measurements of strain rate and strain by Doppler tissue imaging should be taken into account when designing studies using this new technology. Approaches to potentially reduce this variation should be addressed in future studies.

Echocardiography, Doppler↗

Echocardiographic indices of increased left ventricular filling pressure and dilation after acute myocardial infarction.

The relationship between echocardiographic indicators of acute and chronic left ventricular (LV) filling pressure and LV dilation after acute myocardial infarction was assessed in 47 patients. The ratio of early transmitral flow velocity to early mitral annulus velocity (E/e') reflects acute LV filling pressure and the indexed volume of the left atrium is an indicator of chronic LV filling pressure. E/e' was higher (19 vs 10, P = .001) among patients who experienced a greater than 15% increase in indexed LV end-diastolic volume (remodeling group, n = 10). Receiver operating characteristic curve analysis confirmed that E/e' was a predictor of remodeling (area under the curve 0.83, P = .002). Patients with E/e' greater than 15 had a mean increase in indexed LV end-diastolic volume of 9.3 versus 1.7 mL/m2 in patients with E/e' 15 or less (P = .01). Multivariable regression analyses confirmed that E/e' was the strongest independent predictor of remodeling in this cohort (odds ratio 1.39, P = .01). There was no relationship between indexed volume of the left atrium and LV dilation. These data suggest that the E/e' ratio may be a useful predictor of LV dilation after acute myocardial infarction. In particular, an E/e' ratio greater than 15 identifies patients at increased risk.

Aged↗

Impact of preload and afterload on global and regional right ventricular function and pressure: a quantitative echocardiography study.

BACKGROUND: Several quantitative echocardiographic measures of global and regional right ventricular (RV) function have been proposed, but knowledge of the impact of increases in preload and afterload is limited. METHODS: Seventeen healthy participants were exposed to increased preload by rapid infusion of 30 mL/kg of saline over 15 minutes, and to increased afterload simulated in an 16- to 18-hour stay in a controlled hypoxic environment (fractional concentration of oxygen in inspired gas = 12.3%). Two-dimensional, Doppler, and Doppler tissue echocardiography evaluations were performed to evaluate global and regional RV function, with changes evaluated by paired analysis. RESULTS: Peak tricuspid regurgitation velocity increased in both conditions, whereas the RV end-diastolic diameter and acceleration time of the pulmonary forward flow only increased with increased preload and afterload, respectively. Estimates of RV function and contractility remained stable: no changes in the RV isovolumic acceleration (1.6 +/- 0.6 vs 1.6 +/- 0.4 and 1.3 +/- 0.4 cm/s2) or tricuspid annular plane systolic excursion (2.5 +/- 0.4 vs 2.5 +/- 0.3 and 2.6 +/- 0.3 cm) were seen (baseline compared with increased afterload and preload, respectively). The RV index of myocardial performance was increased with increased afterload (0.26 +/- 0.08 vs 0.34 +/- 0.13, P < .05), whereas no changes with increased preload were seen. Changes in loading conditions did not affect the regional strain. CONCLUSION: Moderate volume and pressure loading of the RV induces detectable changes in the RV pressure and morphology. Modern echocardiographic measures of systolic RV function seem stable with moderate increases in preload and afterload.

Adult↗

The prognostic value of pulmonary vascular capacitance determined by Doppler echocardiography in patients with pulmonary arterial hypertension.

OBJECTIVES: We sought to determine if a novel measurement of pulmonary vascular (PV) capacitance (PVCAP) by Doppler echocardiography predicts all-cause mortality in patients with primary pulmonary arterial (PA) hypertension (PPAH). BACKGROUND: The prognosis of patients with PPAH is variable and has been difficult to predict using clinical or hemodynamic parameters. PVCAP is a measure of the workload on the right ventricle (RV) and we recently have shown that PVCAP determined by cardiac catheterization is a strong predictor of survival. This same hemodynamic information to calculate PVCAP can be derived from Doppler echocardiography. Therefore, the purpose of this study was to determine if PVCAP from noninvasive Doppler echocardiography would be a useful measure of survival in patients with PPAH. METHODS: We analyzed clinical and hemodynamic variables on all patients with PPAH who had a right heart catheterization and echocardiogram from January to December 1999. Because capacitance is directly proportional to stroke volume and inversely proportional to PA pulse pressure, PVCAP was defined as stroke volume/pulse pressure. PVCAP was derived noninvasively from a comprehensive 2-dimensional and Doppler echocardiogram. Using the peak systolic tricuspid regurgitation velocity and the end-diastolic pulmonary regurgitation velocity, the modified Bernoulli equation was used to calculate the PA systolic and diastolic pressures, respectively. Stroke volume was obtained using the volumetric flow through the left ventricular outflow tract. PVCAP was then analyzed as a predictor of mortality, adjusting for other known modifiers of risk. RESULTS: In all, 54 patients (13 men) were studied with a mean age of 44 +/- 11 years, ejection fraction of 62 +/- 11%, and RV systolic pressure of 90 +/- 21 mm Hg. In all, 24% were in World Health Organization (WHO) class II, 52% in class III, and 24% in class IV. During follow-up of 1498 +/- 108 days, 12 patients died. The strongest noninvasive predictor of mortality was PVCAP (risk ratio 3.0/mL/mm Hg decrease in PVCAP, 95% confidence interval 1.2-8.0, P = .0212). WHO class, RV index of myocardial performance, RV systolic pressure, and RV ejection time were weaker predictors. PVCAP was also a stronger predictor of mortality than invasively determined PV resistance, right atrial pressure, and mean PA pressure. In multivariate analysis, PVCAP was the only noninvasive predictor of mortality. In quartile analysis the lowest PVCAP quartile had a 4-year mortality of 39% whereas the highest PVCAP had a mortality of 7%. CONCLUSION: The novel measure of PVCAP, as determined by Doppler echocardiography, is a strong noninvasive predictor of mortality in patients with PPAH and adds prognostic value to conventional risk markers.

Adult↗

Role of biplane and biplane echocardiographically guided 3-dimensional echocardiography during dobutamine stress echocardiography.

Image acquisition time and wall-motion score of conventional 2-dimensional (2D) dobutamine stress echocardiography (DSE) were compared with those of biplane and 3-dimensional (3D) DSE in 50 patients (age 67 +/- 13 years) with regular rhythms during clinically indicated DSE. Commercially available systems were used for the study. We used a conventional transducer for 2D and a matrix-array transducer (x4 or x3-1) for two biplane (60- and 120-degree) images and one 3D full-volume image. Image quality was scored as 1 = good; 2 = adequate; and 3 = inadequate. Segmental wall-motion scores for each method were analyzed in blinded fashion. Acquisition times of biplane (9.3 +/- 2.8 seconds) and biplane-guided 3D (additional 2.6 +/- 1.0 seconds) echocardiography were significantly shorter than those of conventional 2D DSE (60.0 +/- 26.7 seconds) (P < .001). Image quality was adequate or good in 94% for biplane and 96% for 3D echocardiography. Agreement of segmental wall-motion score was present in 87.6% of segments for 2D versus biplane and 85.9% for 2D versus 3D at baseline and in 88.0% for 2D versus biplane and 87.4% for 2D versus 3D at peak stress. Acquisition of biplane or biplane-guided 3D volumetric data during DSE with use of a new matrix-array transducer was feasible and shortened image acquisition time without affecting the diagnostic yield compared with conventional 2D imaging.

Aged↗

Abnormal longitudinal myocardial functional reserve assessed by exercise tissue Doppler echocardiography in patients with hypertrophic cardiomyopathy.

BACKGROUND: Previous studies have shown that mitral annular velocities are reduced in patients with hypertrophic cardiomyopathy (HCM). However, the response of systolic and diastolic velocities of the mitral annulus to exercise in patients with HCM has not been explored previously. Because pathologic left ventricular (LV) hypertrophy is associated with myocardial fibrosis, particularly in the subendocardium, we hypothesized that mitral annular systolic and diastolic velocities during exercise and at rest would be abnormal in patients with HCM. METHODS: Mitral septal annular systolic (S') and early diastolic (E') velocities were measured at rest and during graded supine bicycle exercise (25 W, 3-minute increments) in 40 patients with HCM (29 male, mean age 56 years) and 41 age- and sex-matched control subjects. LV diastolic and systolic longitudinal function reserve index were calculated using a new formula. RESULTS: There were no significant differences in mitral inflow velocities (early mitral filling velocity [E], E/A, deceleration time of E velocity [DT]) at rest between the two groups except late mitral filling (A) velocity, which was higher in control group. Increase in E' with exercise was significantly smaller in patients with HCM compared with control subjects (1.7 +/- 1.3 vs 3.4 +/- 2.5 cm/s from base to 25 W, P = .0006; 2.2 +/- 1.9 vs 4.5 +/- 2.8 cm/s from base to 50 W, P = .0002). Although LV ejection fraction at rest was significantly higher in patients with HCM compared with that of control subjects (71 +/- 7 vs 66 +/- 7, P = .0019), S' at rest (6.0 +/- 1.2 vs 6.8 +/- 1.1 cm/s, P = .011) was significantly lower in patients with HCM. Although a significant increase in S' was detected with exercise in control subjects, increase in S' with exercise was blunted in patients with HCM (6.4 +/- 1.4 vs 8.5 +/- 2.5 cm/s at 25 W, P = .0004; 7.0 +/- 1.4 vs 9.5 +/- 2.4 cm/s at 50 W, P < .0001). Longitudinal systolic (0.37 +/- 0.85 vs 1.47 +/- 1.75 cm/s at 25 W, P = .0034; 0.79 +/- 1.08 vs 2.32 +/- 1.66 cm/s at 50 W, P = .0001) and diastolic (1.29 +/- 1.06 vs 2.84 +/- 2.12 cm/s at 25 W, P = .0002; 1.63 +/- 1.46 vs 3.77 +/- 2.31 cm/s at 50 W, P < .0001) function reserve index was significantly lower in patients with HCM compared with that of control subjects. CONCLUSION: Augmentation of LV longitudinal function during exercise is blunted in patients with HCM, suggesting longitudinal functional reserve and resting longitudinal function is abnormal in these patients.

Cardiomyopathy, Hypertrophic↗