Abnormalities of diastolic function precede dilated cardiomyopathy associated with Duchenne muscular dystrophy.
Explore the source record for details and available documents.
Age Distribution↗
Biomedical subjects
Erik C Michelfelder
Publications and source records attributed to Erik C Michelfelder.
Impaired systemic ventricular relaxation affects postoperative short-term outcome in Fontan patients.
OBJECTIVES: Systemic ventricular end-diastolic pressure has been used as a predictor of outcome in patients undergoing the Fontan operation. However, this index only evaluates late diastolic function and does not assess active ventricular relaxation during the phase of early diastole, a key component of systemic venous pathway flow. This study sought to examine whether impaired preoperative systemic ventricular relaxation, expressed as the time constant of isovolumic relaxation (tau), affects short-term postoperative outcome in Fontan patients. METHODS: All patients who underwent Fontan operation between May 1998 and November 2001 were enrolled. Tau was calculated from digitized preoperative systemic ventricular pressure tracings. Standard preoperative invasive indices were also recorded and analyzed. These independent variables were then entered into a multiple stepwise regression model, with length of intensive care unit stay, length of hospital stay, and prolonged pleural effusion as outcome variables. RESULTS: Twenty-seven patients fulfilled inclusion criteria. Systemic left ventricle predominated, and all patients had undergone prior staged palliation. Extracardiac Fontan was the commonest operative technique. Of the independent variables examined, tau was the only statistically significant predictor of length of intensive care unit stay (P <.001) and length of hospital stay (P =.002). None of the independent variables predicted pleural effusion greater than 10 days. CONCLUSIONS: Tau was the only significant preoperative invasive predictor of short-term outcome in the Fontan patients. This illustrates the importance of systemic ventricular relaxation and highlights the need for a more comprehensive assessment of diastolic function before the Fontan operation.
Adolescent↗
Pancreatitis in Fontan patients is related to impaired ventricular relaxation.
BACKGROUND: Pancreatitis following cardiopulmonary bypass is a well-known complication in adults undergoing cardiac surgery. However, the occurrence of pancreatitis in pediatric patients undergoing repair of congenital heart disease is under-appreciated. Post-Fontan patients are particularly prone to postoperative pancreatitis. In an effort to identify specific perioperative factors predictive of postoperative pancreatitis, we retrospectively reviewed a group of Fontan patients. METHODS: From June 1996 to June 2001, 40 patients underwent a modified Fontan operation. Four patients developed acute pancreatitis postoperatively. The preoperative, intraoperative, and postoperative hemodynamics and ventricular function parameters were retrospectively analyzed and compared to 10 randomly selected Fontan patients who did not have pancreatitis. Preoperative echocardiographic and angiographic data, including digitized ventricular pressure tracings, were reviewed to obtain ventricular relaxation time constant (tau), pulmonary vascular resistance (PVR), ventricular end diastolic pressure (VEDP), positive dp/dt and negative dp/dt values. RESULTS: Patients developing acute pancreatitis had very high mortality (50%) compared to no mortality in the control group. The mean preoperative tau was significantly prolonged (41 ms vs 26 ms in control group, p < 0.001), and pre operative systemic output (Qs) lower in the pancreatitis group (mean 2.75 L/min/m2) compared with controls (Qs of 5.09 L/min/m2, p < 0.03). CONCLUSIONS: Impaired ventricular relaxation and decreased preoperative cardiac output are predictive of increased risk of postoperative pancreatitis in Fontan patients. Evaluation of preoperative diastolic function in these patients may provide additional insights in to clinical outcome following the Fontan procedure.
Acute Disease↗
Color M-mode and Doppler tissue evaluation of diastolic function in children: simultaneous correlation with invasive indices.
OBJECTIVE: The purpose of this study was to explore the validity of diastolic indices derived from color M-mode Doppler and Doppler tissue imaging in a heterogeneous group of pediatric patients by comparing them with simultaneously obtained invasive indices of diastolic function. METHODS: A total of 20 children undergoing left heart catheterization had echocardiographic images recorded simultaneously with high-fidelity left ventricular (LV) pressure tracings. Transmitral Doppler, pulmonary vein Doppler, Doppler tissue imaging, and color M-mode Doppler flow propagation velocity were recorded. LV peak negative dP/dt, the time constant of isovolumic relaxation, and LV end-diastolic pressure were compared with the echocardiographic indices. RESULTS: The ratio of peak E-wave mitral velocity/propagation velocity correlated significantly with LV end-diastolic pressure (r = 0.71; P <.001). Propagation velocity correlated with the time constant of isovolumic relaxation (r = -0.56; P =.01) and peak negative dP/dt (r = 0.50; P <.03). Septal mitral annular myocardial velocity correlated significantly with the time constant of isovolumic relaxation (r = -0.58, P =.01). CONCLUSION: The newer diastolic indices derived from color M-mode Doppler and Doppler tissue imaging appear to be a helpful adjunct in the noninvasive assessment of diastolic function in children.
Adolescent↗
Moderate-dose dobutamine maximizes left ventricular contractile response during dobutamine stress echocardiography in children.
BACKGROUND: Assessment of ventricular contractile reserve by dobutamine stress echocardiography (DSE) may be a powerful tool for detection of subclinical ventricular dysfunction, however, the hemodynamic dose-response relationship during DSE in children has not been established. METHODS: To characterize changes in hemodynamics and ventricular contractility during DSE in children, 26 participants (age 8.3 +/- 4.8 years; 17 male/9 female) with normal resting left-ventricular function underwent DSE. Participants with abnormal wall motion at rest or during DSE, or rejection were excluded. Left ventricular M-mode echocardiography and carotid pulse tracings were obtained at each stage for calculation of shortening fraction, velocity of circumferential fiber shortening (VCFc), and end-systolic wall stress (WS). Contractility was expressed as the difference between actual and predicted VCFc for measured WS. Dose-response curves for shortening fraction, VCFc, WS, and contractility (the difference between actual and predicted VCFc for measured WS) were obtained. RESULTS: Stepwise changes in contractility, systolic blood pressure, WS, and left ventricular shortening fraction were observed at doses up to, but not beyond, 20 microg/kg/min. Increases in double product were observed at doses up to 30 microg/kg/min. CONCLUSIONS: DSE at a dobutamine dose of 20 microg/kg/min is optimal to fully assess contractile reserve in children. Lesser doses may provide insufficient stress, whereas higher doses may incur unnecessary increases in myocardial oxygen consumption and side effects.
Adolescent↗
Does assessment of pretest probability of disease improve the utility of echocardiography in suspected endocarditis in children?
OBJECTIVE: To compare the yield rate (YR) of echocardiography when evaluating children with suspected infectious endocarditis (IE) in both the actual clinical setting and in the hypothetic setting where strict clinical criteria are applied. Study design Medical records of 101 children undergoing echocardiography for suspected IE were reviewed. Echocardiograms with positive findings were identified and the actual diagnostic YR was calculated. With the use of clinical criteria proposed by von Reyn (VR), the probability of IE was retrospectively classified as (1) rejected, (2) possible, or (3) probable. Theoretic YR of echocardiography was calculated for each classification. RESULTS: The actual YR of echocardiography was 12% (12/101). The YR of echocardiography by VR class was 0% in rejected, 20% in possible, and 80% in probable cases (chi(2) = 55.1, P <.0001). Echocardiography did not change the probability of IE in any patient classified as rejected, but allowed reassignment of disease probability in a significant proportion of patients with possible or probable IE. CONCLUSIONS: The YR of echocardiography was significant when clinical probability of IE was intermediate-to-high, and low, with marginal clinical utility, when clinical probability was low. Strict pretest assessment of disease probability may lead to more effective utilization of echocardiography in this population.
Bacteria↗
Cardiovascular physiology during supine cycle ergometry and dobutamine stress.
PURPOSE: This study compared cardiac hemodynamics during supine cycle ergometry and dobutamine stress. METHODS: Thirty-two healthy volunteers (19 female, 13 male, 23.5 +/- 3.5 yr old) completed respective tests on separate days and in random order. Heart rate, blood pressure, and cardiac output were recorded at baseline and peak stress. Echocardiographic measures included left ventricular end-diastolic dimension, fractional shortening, heart rate corrected velocity of circumferential fiber shortening, end-systolic wall stress, and the difference between measured and predicted fiber shortening for measured wall stress. RESULTS: Compared with peak exercise, dobutamine infusion resulted in lower cardiac output (12 +/- 2 vs 16 +/- 4 l x min(-1), P < 0.0001), heart rates (163 +/- 7 vs 175 +/- 12 beats x min(-1), P < 0.0001), and systolic blood pressure (160 +/- 22 vs 185 +/- 20 mm Hg, P < or = 0.0001). Echocardiography demonstrated smaller left ventricular end-diastolic dimension (4.2 +/- 0.7 vs 4.5 +/- 0.7 cm, P = 0.013), higher fractional shortening (0.55 +/- 0.07 vs 0.50 +/- 0.06%, P < 0.001), higher VCFc (2.07 +/- 0.36 vs 1.54 +/- 0.20 circs x s(-1), P < 0.001) higher VCFdiff (0.94 +/- 0.35 vs 0.48 +/- 0.20 circs x s(-1), P < 0.001), and lower end-systolic wall stress (25 +/- 11 vs 42 +/- 16 g x cm(-2), P < 0.001). The stress-velocity relationship during dobutamine demonstrated higher y-intercept and steeper slope, indicating greater load-independent contractility. CONCLUSION: The cardiovascular adaptation to exercise and dobutamine stress differ significantly. Cardiac output during peak exercise is greater than during peak dobutamine secondary to increased heart rate and stroke volume. Despite a greater increase in contractility and decrease in afterload, a smaller increase in cardiac output during dobutamine stress may be secondary to limited ventricular preload.
Adaptation, Physiological↗
Effect of superior cavopulmonary anastomosis on the rate of tricuspid annulus dilation in hypoplastic left heart syndrome.
Explore the source record for details and available documents.
Anastomosis, Surgical↗
Conversion to digital technology improves efficiency in the pediatric echocardiography laboratory.
BACKGROUND: Although the videotape method (VTM) is commonly used to record and intrepret ecocardiographic images, many pediatric echocardiographers are considering acquiring to, interpreting from, and storing their images to digital disk using the single-beat digital acquisition method (SBM). The paucity of image redundancy using SBM should translate into improved laboratory efficiency compared with VTM, but hard data are lacking. The purpose of this study was to test the hypothesis that the time to acquire images to videotape using VTM and to disk using SBM would be the same for normal hearts and corresponding congenital heart diseases, but interpretation times would be shorter using SBM. METHODS: We measured the times to acquire and interpret 403 echocardiograms using standard VTM from Children's Hospital in Cincinnati, Ohio, and 352 echocardiograms acquired using SBM from Children's Hospital in San Diego, Calif. Diagnostic categories at each site included: (1) normal, (2) simple shunt or isolated valve disease, and (3) multiple-lesion disease. RESULTS: As a group, SBM echocardiograms included more hemodynamic measurements and took more time to acquire (P <.037), but less time to read (P <.001) than corresponding images acquired using VTM. Using SBM, it took more time to acquire normals and isolated valve or shunt lesions, whereas the average time to acquire multiple-lesion disease was the same using both VTM and SBM. With SBM, in contrast, interpretation times were significantly less for all corresponding diagnoses. CONCLUSION: SBM studies took longer to acquire because more hemodynamic measurements were acquired, but they were read in less time than corresponding VTM studies even though all videotapes were replayed in search fast-forward mode. Pediatric echocardiographers can increase their laboratory efficiency by converting from VTM to SBM.
Analog-Digital Conversion↗