Biomedical subjects
Publications and source records attributed to M A Fogel.
Persistent fifth aortic arch was suspected by echocardiography and confirmed by magnetic resonance imaging (MRI) in an infant with a heart murmur. Selected images including three dimensional reconstruction from MRI demonstrating this very rare congenital anomaly are presented.
BACKGROUND: Although the interposition of left ventricular apical to descending aorta conduits has diminished with the advent of the Ross-Konno operation, it remains a useful option. We reviewed our institutional experience imaging these conduits and tested the hypothesis that the gradient across the native left ventricular outflow tract (LVOT) by echocardiography correlated with the conduit gradient by cardiac catheterization. In a patient with an unobstructed conduit, no gradient should exist across the native LVOT. METHODS: This was a retrospective review of the echocardiography, cardiac catheterization, magnetic resonance imaging (MRI) data, and history of 9 patients with these conduits over an 8-year period. In 7 of 9 patients, 8 conduit obstruction events were assessed by Doppler interrogation of the native LVOT and by cardiac catheterization. Five patients underwent 6 MRI scans. RESULTS: In all cases of obstruction diagnosed by catheterization (56.3 +/- 21.9 mm Hg), Doppler echocardiography demonstrated gradients across the native LVOT (69.3 +/- 21.2 mm Hg, r = 0.67). Because 2D echocardiography could not visualize the entire conduit in any patient, 2- and 3-dimensional MRI was used successfully to evaluate anatomy and identify the site of obstruction. All patients manifested conduit obstruction. Four (44%) of 9 patients died, 3 underwent the Ross operation, 1 continues to live with his original conduit, and 1 was lost to follow-up. CONCLUSIONS: A gradient by Doppler interrogation of the native LVOT is an indirect means of assessing conduit obstruction. MRI is a useful tool to complement anatomic diagnosis by echocardiography. Conduit obstruction is common, and late mortality rates appear to be high.
BACKGROUND: Intracardiac baffles and extracardiac conduits have been used in the reconstructive surgery of a broad spectrum of congenital cardiac malformations. Periodic evaluation of these structures may not lend itself readily to echocardiographic and angiographic imaging. The purpose of the study was to describe the experience of our institution with the use of magnetic resonance imaging (MRI) in evaluating conduits and baffles and to describe the simplified approach we developed to image these structures, which allows for grouping individual lesions into broad categories. METHODS AND RESULTS: We retrospectively reviewed our MRI experience in visualizing these structures from 1989-1996. One hundred thirty-nine patients underwent MRI to visualize 144 structures (116 baffles, 28 conduits). The 116 baffles included 86 Fontan, 16 Mustard, 6 Senning, 6 left ventricle to aorta, 1 right ventricle to aorta, and 1 pulmonary vein to left atrium baffle. The 28 conduits included 15 right ventricle to pulmonary artery, 4 left ventricular apical to aorta, 2 left ventricle to pulmonary artery, 3 aorta to aorta, 2 inferior vena cava to left atrium conduits, and 2 aortic root replacements. Of the 3 aortic-aortic conduits, 1 was in conjoined twins. Both inferior vena cava-left atrial conduits were in a Baffes procedure. An infectious mass missed by echocardiography in a right ventricle to pulmonary artery conduit was visualized by MRI. With multiplanar reconstruction, contiguous images were stacked atop each other and resliced to define the salient points of the anatomy. Three-dimensional reconstruction further added to this delineation. All structures were visualized successfully, and an assessment of obstruction was made. Multiple examples of conduit and baffle narrowing were diagnosed by spin echo and cine MRI and were subsequently confirmed by catheterization and surgical inspection. CONCLUSION: MRI, with multiplanar and 3-dimensional reconstruction, is useful in examining the variety of baffles and conduits used in congenital heart surgery. MRI can add to the care of patients whose echocardiographic windows or whose angiographically overlapping structures do not allow adequate delineation of conduits and baffles.
BACKGROUND: Most of what is known about diastolic function in normal infants is derived from flow and pressure measurements. Little is known about regional diastolic strain and wall motion. METHODS AND RESULTS: Magnetic resonance tissue tagging was performed in 11 normal infants to determine regional diastolic strain and wall motion. Tracking diastolic motion of the intersection points and finite strain analysis yielded regional rotation, radial displacement, and E(1) and E(2) strains at 3 short-axis levels (significance was defined as P<0.05). E(2) "circumferential lengthening" strains were significantly greater at the lateral wall, regardless of short-axis level, whereas E(1) "radial thinning" strains were similar in all wall regions at all short-axis levels. In general, no differences were noted in strain dispersion within a wall region or in endocardial/epicardial strain at all short-axis levels. At all short-axis levels, septal radial motion was significantly less than in other wall regions. No significant differences in radial wall motion between short-axis levels were noted. Rotation was significantly greater at the apical short-axis level in all wall regions than in other short-axis levels, and it was clockwise. At the atrioventricular valve, septal and anterior walls rotated slightly clockwise, whereas the lateral and inferior walls rotated counterclockwise. CONCLUSIONS: Diastolic biomechanics in infants are not homogeneous. The lateral walls are affected most by strain, and the septal walls undergo the least radial wall motion. Apical walls undergo the most rotation. These normal data may help in the understanding of diastolic dysfunction in infants with congenital heart disease.
BACKGROUND: A complete understanding of fluid mechanics in Fontan physiology includes knowledge of the caval contributions to right (RPA) and left (LPA) pulmonary arterial blood flow, total systemic venous return, and relative blood flow to each lung. METHODS AND RESULTS: Ten Fontan patients underwent cine MRI. Three cine scans of the pulmonary arteries were performed: (1) no presaturation pulse, (2) a presaturation pulse labeling inferior vena cava (IVC) blood (signal void), and (3) a presaturation pulse labeling superior vena cava (SVC) blood. The relative signal decrease is proportional to the amount of blood originating from the labeled vena cava. This method was validated in a phantom. Whereas 60+/-6% of SVC blood flowed into the RPA, 67+/-12% of IVC blood flowed toward the LPA. Of the blood in the LPA and RPA, 48+/-14% and 31+/-17%, respectively, came from the IVC. IVC blood contributed 40+/-16% to total systemic venous return. The distributions of blood to each lung were nearly equal (RPA/LPA blood=0.94+/-11). CONCLUSIONS: In Fontan patients with total cavopulmonary connection, SVC blood is directed toward the RPA and IVC blood is directed toward the LPA. Although the right lung volume is larger than the left, an equal amount of blood flow went to both lungs. LPA blood is composed of equal amounts of IVC and SVC blood because IVC contribution to total systemic venous return is smaller than that of the SVC. This technique and these findings can help to evaluate design changes of the systemic venous pathway to improve Fontan hemodynamics.
Abnormal ventricular systolic torsion is present during histological rejection in adult cardiac transplant patients. Because biomechanical properties of transplanted hearts in the baseline state have not been studied in children, pediatric patients were evaluated to quantify ventricular wall motion and strain. Eight transplant studies and eight normal controls were evaluated. Magnetic resonance tagging was performed to determine radial shortening, twist, and strain in four ventricular anatomic areas at two short-axis levels. Controls had counterclockwise twist. Six transplant studies had clockwise twist, six had akinetic regions, and all had regions of no twist. One demonstrated paradoxical motion of the septum. A comparison between transplant patients and controls revealed strain to be similar in all regions except one (superior wall at the atrioventricular valve level) and strain distribution to be different only in two of eight regions. Pediatric transplant patients demonstrate regional wall motion abnormalities in the absence of rejection. Compared with normal controls, the transplanted left ventricle maintains normal strain in the presence of abnormal twist. This may be a compensatory mechanism and have clinical implications.
BACKGROUND: Left ventricular (LV) effects on right ventricular (RV) function are well known. Less is understood about the effect of the RV on systemic LV mechanics. To determine this interaction, we compared systemic LVs with and without an RV mechanically coupled to them. METHODS AND RESULTS: MR myocardial tagging was used to examine 18 subjects with systemic LVs: 10 with functional single LVs (SLV) and 8 normal subjects (NL). Tracking the systolic motion of the intersecting stripes were used to determine regional twist and radial motion. Finite strain analysis was applied to derive principal strains at the atrioventricular valve (AVV) and apical short-axis levels and in 4 anatomic wall regions. Similar E1 (circumferential shortening) strain and heterogeneity of strain were noted between SLV and NL except in the septal wall. At the septal wall, NL displayed greater absolute strain (AVV=-0.16+/-0.02, apex=-0.17+/-0.02) and less heterogeneity of strain than SLV (AVV= -0.12+/-0.02, apex=-0.13+/-0.02). Similar E2 (wall thickening) strain and heterogeneity of strain were also noted between SLV and NL except again at the septal wall. At the septal wall, SLV displayed greater absolute E2 strain (AVV=0.17+/-0.08, apex=0.19+/-0.09) and less heterogeneity of strain than NL (AVV=0.07+/-0.07, apex=0.05+/-0.05). SLV twisted significantly less counterclockwise than NL in 6 of 8 wall regions and actually twisted clockwise at the AVV lateral wall. Although there was no significant difference between groups in radial wall motion, the septal and inferior walls of SLV demonstrated significantly less radial motion compared with other SLV walls. CONCLUSIONS: A major influence of the RV on systemic LV strain and radial motion occurs in the septal wall, whereas absence of the RV causes marked differences in LV twist. These findings may yield clues to the long-term functioning of the SLV and be useful in determining strategies for RV augmentation of LV function.
BACKGROUND: This study examined the results of a Fontan operation for patients with acquired atresia of one main branch pulmonary artery. METHODS: The data for 7 patients identified as having a hypoplastic left pulmonary artery discontinuous from the right pulmonary artery were compared with those for 65 patients with continuous pulmonary arteries who consecutively underwent a completion Fontan procedure. RESULTS: No significant differences were found preoperatively with respect to right atrial pressure, aortic saturation, ventricular end-diastolic pressure, pulmonary artery pressure, pulmonary blood flow, or pulmonary vascular resistance. In the first 24 postoperative hours, there were no significant differences in heart rate, urine output, systemic venous pressure, or pulmonary venous pressure. Also, data regarding hospitalization length, effusions, and mortality were similar between the two groups. Postoperative systemic arterial saturation was lower in the one-lung group. There were no early postoperative deaths in the one-lung group, and 5 of the 7 patients are long-term survivors. CONCLUSIONS: A completion Fontan procedure can be successfully performed in patients with a hypoplastic and discontinuous left pulmonary artery, although postoperative systemic arterial saturation is not as high as in patients with continuous pulmonary arteries.
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Magnetic resonance imaging is a unique and insightful tool for the assessment of structure and function in congenital heart disease. For anatomic assessment, the large field of view, lack of limitation by patient size, and ability to create three-dimensional surface displays from routine imaging acquisitions offer several advantages over other modalities. The ability of magnetic resonance imaging to assess the volume and mass of bizarre ventricular shapes accurately and myocardial tissue and blood tagging as well as phase encoded velocity mapping has enhanced research in pediatric cardiology. Newer techniques, such as oxygen-sensitive magnetic resonance imaging and echo-planar magnetic resonance imaging, promise even further advances in research and in clinical applications.
Vancomycin use is common in hemodialysis patients, due in part to the ease of dosing, but can lead to the development of resistant organisms, including vancomycin-resistant enterococcus. Alternate antibiotics may be equally effective and allow similar dosing in the chronic hemodialysis population. A retrospective review of culture results from a 217-patient, non-hospital-based outpatient hemodialysis center was performed over a 7-month period. Wound and blood culture sensitivity to cefazolin, vancomycin, cefazolin plus gentamicin, and vancomycin plus gentamicin was analyzed. Cefazolin was equivalent to vancomycin for empiric treatment of clinically significant infections in a population with a low rate of methicillin-resistant Staphylococcus aureus infection. Cefazolin plus gentamicin was superior to vancomycin alone. The vancomycin plus gentamicin combination did provide minimally broader coverage than the cefazolin plus gentamicin combination. A prospective pharmacokinetic analysis of postdialysis cefazolin dosing was performed in anuric chronic hemodialysis patients dialyzed with polysulfone dialyzers. Peak, predialysis, and postdialysis cefazolin levels were obtained. Nondialysis clearance of cefazolin was sufficiently low (k(e), 0.027; t(1/2), 26.4 hours) and dialysis clearance sufficiently high (k(e), 0.254; t(1/2), 3.19 hours) to provide for safe and effective peak and trough cefazolin levels with postdialysis dosing in anuric hemodialysis patients. In conclusion, cefazolin alone or with gentamicin in an appropriate empiric antibiotic choice in chronic hemodialysis patients dialyzed in a nonhospital setting with low methicillin-resistant S. aureus infection rates. For infections with documented sensitivity to cefazolin, a 1 g intravenous dose postdialysis (750 mg in patients weighing <50 kg) is safe and effective.
In this study we investigated the patterns of pulmonary venous flow in children with functional single ventricles to obtain a better understanding of the determinants of transpulmonary blood flow. Sixty-eight patients with functional single ventricles and aortopulmonary shunt (n = 34, group I), or superior cavopulmonary connection (n = 34, group II) underwent transesophageal Doppler echocardiographic assessment of flow in the left upper pulmonary vein before undergoing the next stage of surgery. Twelve patients from group II also underwent simultaneous evaluation of superior vena caval flow. Biphasic forward pulmonary venous flow was noted in 62 patients in sinus rhythm (S wave in systole, D wave in diastole); in 6 patients with junctional rhythm, significant early systolic reversal of flow was present. Both the S- and D-wave velocity-time integrals (VTI) were greater in group I than in group II (S(VTI) 9.9 +/- 4.2 vs 8.0 +/- 2.6, p = 0.02; D(VTI) 8.0 +/- 3.5 vs 4.2 +/- 2.6, p <0.001). In both groups, pulmonary venous flow was predominantly systolic; however, the proportion of flow during ventricular systole was significantly greater in group II than in group I (S(VTI)/D(VTI) group II: 2.4 +/- 1.5; group I 1.4 +/- 0.5, p = 0.001; percent systolic fraction of pulmonary venous flow group II = 67%, group I = 56%, p <0.001). Analysis of superior vena caval flow in group II revealed a single predominant wave with onset at early systole and peak in late systole at a mean of 150 ms after the pulmonary venous S-wave peak. Our data suggest that ventricular systole (i.e., atrial relaxation, atrioventricular valve descent) asserts great influence on transpulmonary blood flow in the functional single ventricle.
BACKGROUND: A high incidence of pulmonary arteriovenous malformations (PAVMs) has been reported in patients who have polysplenia and congenital heart disease after superior cavopulmonary anastomosis. Interruption of hepatic venous return to the pulmonary circulation is believed to potentiate the development of PAVMs. Surgical inclusion of hepatic flow in the pulmonary circulation may result in their resolution. METHODS: We reviewed 3 patients with congenital heart disease and polysplenia in whom PAVMs developed and who had subsequent hepatic vein inclusion in the pulmonary circulation. RESULTS: Patients underwent superior cavopulmonary connection at a median age of 8 months. The PAVMs were diagnosed at a median duration of 8 months after operation (arterial saturation <75% in room air). Hepatic venous flow was included in the pulmonary circulation at operation. Resolution of PAVMs occurred at a median duration of 7 months after operation (arterial saturation >90% in room air). CONCLUSIONS: Surgical inclusion of hepatic venous blood in the pulmonary circulation results in the resolution of PAVMs. Electively associating the hepatic veins with the pulmonary vasculature may prevent the development of PAVMs in patients who are at risk.
BACKGROUND: The aorta that has undergone an aorta-pulmonary artery anastomosis may not exhibit the same velocity profile as the nonreconstructed aorta, whose velocity profile is thought to be uniform across the vessel diameter (plug flow). This may have an impact on fluid dynamics and will alter Doppler flow calculations. Our objective was to determine the impact of surgical reconstruction on the velocity and flow profiles of the reconstructed ascending and descending aorta. METHODS: Using a magnetic resonance imaging tagging technique that labels flowing blood (bolus tagging), we studied 22 patients (mean age, 8.6 +/- 4.7 years) who had had a Fontan procedure. A cine sequence labeled the blood and acquired the image after 20 ms in the middle of the ascending aorta and behind the left atrium in the descending aorta. The repetition time was 50 ms. RESULTS: The reconstructed ascending aorta displayed a velocity profile skewed anteriorly, whereas in the nonreconstructed aorta, the velocity profile was flat. Reconstructed aortas also displayed flows that were higher anteriorly, took a longer time to reach maximum velocity, and were less like "plug" flow than the nonreconstructed aorta. The descending aorta, regardless of whether aortic reconstruction was present, displayed velocity profiles (at various phases of systole) skewed posteriorly. CONCLUSIONS: The reconstructed aorta displays disturbed flow, and the velocities across the ascending aortic diameter are more varied than those in aortas without reconstruction and are skewed anteriorly. The descending aortic velocity profile in children is skewed posteriorly, regardless of whether aortic reconstruction is present. This information may help design and build a "better" aortic reconstruction.
OBJECTIVES: Our objectives were twofold: (1) to determine cardiac and respiratory dependency of systemic venous pathway flow of patients having the Fontan operation with a total cavopulmonary connection and (2) to describe the velocity profile. Systemic venous pathway flow is hypothesized to be mostly respiratory dependent, to be laminar, and to have a smooth velocity profile. METHODS: Twenty-two patients having the Fontan operation (aged 8.6 +/- 4.7 years) underwent magnetic resonance blood tagging (bolus tagging). Systemic venous pathway spin-echo images parallel to the blood flow were used as a localizer. A saturation pulse labeled the blood, and a cine image was acquired at the inferior and superior venae cavae and midportion of the baffle in the systemic venous pathway, triggered to the electrocardiogram and gated to both end-expiration and end-inspiration. Repetition time was 50 msec. RESULTS: Flow in the systemic venous pathway was laminar throughout its course and was found to be phasic to both cardiac and respiratory cycles. Approximately 70% of flow was cardiac dependent, and the rest was respiratory. Highest flow occurred near end-systole and early diastole and in inspiration. Lowest flow occurred in diastasis. Velocity was highest and flow least "pluglike" in the mid-baffle area during cardiac or respiratory imaging (45 +/- 17 and 32 +/- 11 cm/sec, respectively). CONCLUSION: A substantial amount of pulmonary blood flow in patients who have undergone a total cavopulmonary connection type of Fontan operation has a cardiac component. Furthermore, we confirm that this flow is laminar but nonuniform across the systemic venous pathway. Highest flows occurred near end-systole and early diastole, as well as in inspiration, and the lowest flow occurred in diastasis. This information may help in designing the systemic venous pathway and optimizing medical management.
OBJECTIVES: The objectives of this study were to define physiologic effects on and a clinical correlate to coronary blood flow during volume unloading surgery in patients with aortic atresia. METHODS: Twenty-two patients with aortic atresia (group I, 13 patients with stage I reconstruction undergoing hemi-Fontan operation; group II, 9 patients with hemi-Fontan undergoing Fontan operation) underwent perioperative transesophageal echocardiography. Doppler spectral patterns, peak velocity, velocity time integral, and blood flow in the native ascending aorta were measured. Preoperative hemodynamics and postoperative clinical data were analyzed. Significance was defined as p < 0.05. RESULTS: Higher values of coronary blood flow (982.9 +/- 321.7 vs 548.6 +/- 333.8 ml/min per square meter), velocity time integral (20.7 +/- 5.6 vs 12.6 +/- 4.0 cm), and peak velocity (96.1 +/- 21.4 vs 51.0 +/- 18.2 cm/sec) were found before operation in group I than after operation and in group II at both times. Flow changed from predominately systolic in preoperative group I to both systolic and diastolic after operation and in group II. Before operation in groups I and II, a number of hemodynamic parameters such as superior vena cava oxygen saturation correlated with coronary blood flow dynamics. After operation in group II, urine output (r = 0.86) and central venous pressure (r = -0.85) correlated with coronary blood flow dynamics. CONCLUSION: Coronary blood flow parameters were higher in group I as a result of the increased energy needs required to pump to two circulations. No changes were found in group II. A number of coronary blood flow parameters correlated with preoperative hemodynamics and postoperative clinical data. These parameters appear to be useful in assessing the performance status of the myocardium after the Fontan operation, consistent with the notion that myocardial perfusion relates directly to ventricular function.