Biomedical subjects
Publications and source records attributed to M A Fogel.
Visualization of extracardiac conduits was evaluated comparing angiography, echocardiography, and magnetic resonance imaging with 3-dimensional reconstructions. Magnetic resonance imaging afforded visualization of the conduit in its entirety in a higher percentage of patients than the other 2 imaging modalities.
OBJECTIVES: We sought to test the hypothesis that late ventricular geometry and performance changes occur in functional single ventricles as they progress through staged Fontan reconstruction. BACKGROUND: Indexes of ventricular geometry and performance are important in evaluating the functional state of the heart. Magnetic resonance imaging determines these indexes in complex ventricular shapes with minimal geometric assumptions. Previous studies have shown that 1 week after hemiFontan, the mass/volume ratio markedly increases. METHODS: Multiphase, multislice, spin echo (n = 5) and cine (n = 30) magnetic resonance imaging was performed in 35 patients with a functional single ventricle (1 week to 12 years old) at various stages of Fontan reconstruction (15 in the pre hemiFontan stage, 11 after [6 to 9 months] the hemiFontan procedure and 9 after [1 to 2 years] the Fontan procedure). Volume and mass were calculated at end-systole and end-diastole. Ventricular output was then obtained. Ventricular centroid motion was also calculated. RESULTS: No difference was noted (power > 72%) from the pre hemiFontan stage to 6 to 9 months after the hemiFontan procedure in (mean +/- SD) end-diastolic volume (104 +/- 24 vs. 123 +/- 40 cc/m2), mass (171 +/- 46 vs. 202 +/- 61 g/m2), ventricular output (7.9 +/- 2.2 vs. 6.6 +/- 2.4 liters/min per m2) or centroid motion (6.9 +/- 2.8 vs. 6.7 +/- 2. mm/m2). Patients in the Fontan group demonstrated a marked decrease in all indexes, indicating significant volume unloading and decrease in mass and ventricular performance. Mass/volume ratio was not significantly different among all three groups. CONCLUSIONS: No geometric and performance changes from the volume-loaded stage are noted 6 to 9 months after the hemiFontan procedure; however, major changes occur 1 to 2 years after the Fontan procedure. The dramatic changes in the mass/volume ratio seen early after the hemiFontan procedure were not detected at 6 to 9 months. Furthermore diminution of mass, volume and ventricular performance are present at least 2 years after the Fontan procedure.
To determine if strain and wall motion are enhanced in the left ventricle (LV) in a chronically afterload-reduced milieu, a magnetic resonance tagging technique was used to examine 19 subjects: 11 with transposition of the great arteries who have undergone an atrial inversion operation (TGA-LV, 11.6 +/- 4.3 yr postoperative) and eight normal adults. Finite strains (E1), regional twist, and radial motion were calculated at the atrioventricular valve and apical short axis levels in four anatomic wall regions. Strain was greatest in TGA-LV patients (-0.20 +/- 0.02 at the atrioventricular valve septal wall) and was significantly greater than controls in six out of eight regions. Marked differences were noted in the distribution of strain between TGA-LV and normal subjects as well as within the TGA-LV group. Ten of 11 LV of TGA-LV patients twisted clockwise in the lateral or inferior walls and counterclockwise in other walls (more counterclockwise than control subjects), whereas control LV twisted uniformly counterclockwise. The lateral wall of TGA-LV demonstrated the greatest radial inward motion, whereas controls demonstrated uniform radial inward motion. We conclude that the biomechanics of the LV faced with a chronic afterload reduction is enhanced; a marked increase in regional strain is observed in TGA-LV patients. Abnormalities in the distribution of strain were also observed. Markedly abnormal clockwise twist and increased lateral wall motion were demonstrated in TGA-LV patients.
When comparing means, there is no difference between right and left SVC saturations, and the difference does not affect cardiac output calculations. Because of the wide variability between right and left SVC saturations and their calculated cardiac output within patients, along with the higher correlation of left versus right SVC saturation with pulmonary artery saturation, the Fick-derived cardiac index calculation should be interpreted with caution when a left SVC is present. A prospective study with near-simultaneous sampling in all vessels should be undertaken.
BACKGROUND: Ventricular-ventricular interaction is known to occur in normal human heart. To determine whether it plays a role in the function of single right ventricles, systemic right ventricles were compared with and without a left ventricle mechanically coupled to it. METHODS AND RESULTS: A noninvasive magnetic resonance tagging technique (spatial modulation of magnetization [SPAMM]) that lays intersecting stripes down on the myocardium was used to examine 18 patients with systemic right ventricles: 7 with a single right ventricle who have undergone the Fontan procedure (age, 38.8 +/- 8.9 months) and 11 with transposition of the great arteries who have undergone an atrial inversion operation (age, 16.3 +/- 3.9 years). The motion of the intersection points was tracked through systole to determine regional twist and radial shortening. Shortening rates also were evaluated. Finite strain analysis was applied to the grid lines using Delaunay triangulation, and the two-dimensional strain tensor and principal E1 strains were derived for the various anatomic regions. Basal and apical short-axis planes through the ventricular wall were categorized into four distinct regions spaced equally around the circumference of the slice. We observed the following results. (1) Strain was greatest and heterogeneity of strain was least in patients with transposition of the great arteries who were status post atrial inversion operation (six of eight regions). Marked differences were noted in the distribution of strain within a given region, from endocardium to epicardium, and from atrioventricular valve to apical plane between patient subtypes and those with a normal left ventricle. (2) Contrary to the normal subject studied by the use of the same method, for both patient subtypes, there was counterclockwise twist in one region, clockwise twist in the posterior or inferior wall, and a transition zone of no twist at which the two regions of twist met. Normal human adult left ventricles studied in short-axis twist uniformly counterclockwise as viewed from apex to base. (3) Radial inward motion was greatest in the superior wall of both types of systemic right ventricle. The inferior walls of Fontan patients and the posterior (ie, septal) walls of patients with transposition of the great arteries, status post atrial inversion, moved paradoxically in systole. The shortening rate at the atrioventricular valve of patients with transposition of the great arteries, status post atrial inversion, was significantly lower than at the apex or in Fontan patients. CONCLUSIONS: Marked differences in regional wall motion and strain were demonstrated in systemic right ventricles, depending on whether a left ventricle was present to augment its function. Ventricular-ventricular interaction appears to play an important role in affecting the biomechanics of systemic right ventricles. These observations were markedly different from those in the normal systemic left ventricle. These techniques demonstrate tools with which we can begin to evaluate surgical outcomes using regional myocardial mechanics and may provide a clue to single right ventricle failure.
MR imaging allows functional evaluation of the ventricles of the entire heart because it evaluates cardiac anatomy three-dimensionally. Such evaluation is independent of chamber size and shape, and virtually independent of mathematical assumptions. Applying standard measurements of volume and function in children who have undergone multi-staged Fontan operations, we have shown diminished ventricular volumes and mass, and decreased cardiac indices, in post-Fontan procedure. These variations may be predictive of ultimate outcome in these complex patients.
To determine whether systolic regional wall deformation and motion, which may be used as an index of mechanical function, change with surgical intervention in patients with a functional single ventricle, a noninvasive magnetic resonance tagging technique was used to examine 33 such patients at all stages of Fontan reconstruction. The systolic motion of the intersection points was tracked to determine regional twist and radial shortening. Finite strain analysis was applied to the grid lines, and principal E1 strains were derived. The results were as follows. 1) Fontan and prebidirectional cavopulmonary anastomosis (hemiFontan) groups had the highest compressive strains, and regional heterogeneity of strain was least in the Fontan group. 2) Fontan patients had endocardial/epicardial strain different from the other surgical subgroups as well as the normal left ventricle, while the pre- and post-hemiFontan groups had basal/apical short-axis strain different from Fontan patients and normal subjects. 3) Functional single left ventricles had a different strain distribution across wall regions and surgical subgroup from functional single right ventricles. 4) Contrary to the normal human adult studied by the same method, which twists uniformly counterclockwise, 31 of 33 single ventricles, regardless of ventricular morphology or surgical subgroup, twisted counterclockwise in one region, clockwise in another, and met at a "transition zone" of no twist, which had the highest strains of all regions. 5) Radial contraction was greatest in the superior walls and least at the inferior walls of single-ventricle patients regardless of morphology. In the Fontan group, the inferior walls moved paradoxically. In conclusion, markedly different strain characteristics are noted at each stage of Fontan reconstruction, across various wall regions, and between ventricular morphological groups. Differences in regional wall motion were demonstrated in functional single ventricles throughout Fontan reconstruction regardless of morphology, and differences in associated strains and radial contraction were noted across various wall regions and surgical subgroups. These may play an important role in the energetics of the heart and the long-term viability of the single ventricle.
BACKGROUND: Because pulmonary artery size is considered by most investigators to be a major prognosticator of outcome in patients undergoing staged Fontan reconstruction, the objective of the present study was to determine the efficacy of noninvasive measures in determining pulmonary artery size. METHODS AND RESULTS: This study analyzed the T1-weighted, spin-echo magnetic resonance and echocardiographic images of 36 functional single-ventricle patients throughout stages of Fontan reconstruction (prebidirectional and postbidirectional cavopulmonary anastomosis and after Fontan) and compared them with angiography images at cardiac catheterization. Magnetic resonance imaging had a high degree of agreement with angiography, with the McGoon index agreeing better than the Nakata index and absolute right and left pulmonary diameters. Although echocardiography had fair agreement with angiography, it agreed less well and had a wider standard deviation than magnetic resonance imaging for all indexes and measurements and, based on the prediction interval, would be a poorer prospective measure of pulmonary artery size in this population. In addition, echocardiography was a poorer measure of pulmonary artery size as the size of the vessel increases. Magnetic resonance imaging correctly detected five of five patients with nonconfluent branch pulmonary arteries and six of six patients with stenoses, whereas echocardiography was unable to visualize any of the patients with nonconfluent branch pulmonary arteries with certainty and only two of six (33%) with stenoses. CONCLUSIONS: Magnetic resonance imaging is a useful, noninvasive tool to determine pulmonary artery size in patients undergoing Fontan reconstruction and is superior to echocardiography. Echocardiography was a fair predictor of pulmonary artery size, but magnetic resonance imaging agreed with angiography better than echocardiography and outperformed echocardiography in diagnosing branch pulmonary artery discontinuity and stenoses. Magnetic resonance imaging may avoid unnecessary cardiac catheterization, especially in older patients, and may obviate the need for jugular or subclavian catheterization in those who have undergone bidirectional cavopulmonary anastomosis.
It has been previously demonstrated that total heart volume (contents of pericardium) throughout the cardiac cycle varies by < 5% and location of center of mass by < 3 mm. The hypothesis has thus developed that for maximal efficiency, the heart should expend minimal energy in displacing extracardiac structures by maintaining a constant intracycle total heart volume and center of mass. This is achieved in the normal heart mainly by a piston-like movement of the atrioventricular valve plane toward the ventricular apex. As this has never been studied in the single ventricle heart or at various stages of Fontan reconstruction, it is conceivable that these patients may not exhibit the constancy of total heart volume and location of center of mass, which may lead to a poor outcome in some. The total heart volume and center of mass relationship was therefore evaluated in 25 children (0.4 to 237 months) with functional single ventricles at all stages of Fontan reconstruction using multiphase, multislice spin-echo or cine-magnetic resonance imaging. No significant difference was seen in variation between total heart volume and maximal volume between patients before bilateral cavopulmonary anastomosis (hemiFontan) (5.1 +/- 2.9%), after hemiFontan (3.6 +/- 1.6%) and after Fontan (8.2 +/- 7.7%); however, in 4 of 10, 1 of 8 and 5 of 7 patients, respectively, the total heart volume varied by < 5%. Across surgical subgroups, significant differences were found in the center of mass displacement (total, anteroposterior and superoinferior planes) but not in directionality of displacement.(ABSTRACT TRUNCATED AT 250 WORDS)
In passive Heymann nephritis (PHN) glomeruli exhibit marked basement membrane expansion around subepithelial immune deposits but they fail to show any change in mRNA levels of type IV collagen, laminin or fibronectin by Northern and slot-blot analysis, or in the amount or distribution of type IV collagen or laminin by immunohistology for up to 12 weeks after disease onset. On the other hand, in situ hybridization (ISH) revealed the appearance of positive cells exhibiting mRNA for the alpha 1 chain of rat type I collagen two to three weeks after the onset of PHN in all glomeruli of all rats. Positive cells persisted for at least eight weeks. In many glomeruli, the location of the clusters of silver grains suggested that they were in visceral epithelial cells. In controls injected with normal sheep IgG, and in early PHN (< 11 days after sheep anti-Fx1A), glomeruli were negative but cells in the renal capsule and adventitia of vessels showed strong ISH and served as positive controls. RNAse pre-treatment and the "sense" probe gave appropriately negative results. RNA from PHN glomeruli contained an alpha 1 type I collagen transcript of the same size as that from rat fibroblasts. These results show that the evolution of glomerular basement membrane expansion in rat membranous nephropathy coincides with the induction of a matrix gene that is not normally expressed in glomerular cells. Further, they suggest that the intercalation of ectopically-expressed matrix molecules may contribute to the production of a disorganized basement membrane.
To evaluate the efficacy of chest roentgenograms and echocardiograms in identifying pulmonary venous pathway obstruction in patients after the modified Fontan procedure, the records of 297 patients who underwent 307 Fontan procedures between 1984 and 1990 were reviewed. Twelve cases of pulmonary venous pathway obstruction documented by autopsy (3 cases) or cardiac catheterization (9 cases with an A wave gradient greater than or equal to 4 mm Hg) were found in 10 patients (mean age 43 +/- 28 months). The mechanisms of obstruction included narrow pulmonary vein ostia in six cases, narrow left atrial outlet in four and atrial baffle obstruction in three. Two causes of obstruction were present in one case. No patient had pulmonary venous congestion on chest roentgenograms. Pathway diameters indexed to 3 square root of body surface area with two-dimensional echocardiography were found to be 6.8 +/- 1.2 mm/3 square root of m2 in the subcostal frontal view, 7.9 +/- 0.6 mm/3 square root of m2 in the subcostal sagittal view and 6.5 +/- 1.7 mm/3 square root of m2 in the apical "four-chamber" view. These values differed significantly from those in 11 age-matched patients undergoing the Fontan procedure without pulmonary venous pathway obstruction documented by catheterization (p = 0.001). With pulsed Doppler ultrasound, there was a relatively narrow range of velocities distal to the obstruction (1.3 to 2.5 m/s). In five of the seven cases with pulsed Doppler measurements, flow was continuous and the Doppler spectral recordings were not phasic. Thus, in patients who have undergone the Fontan procedure and have pulmonary venous pathway obstruction 1) chest roentgenography cannot be used as a screening tool; 2) distal velocities as low as 1.3 m/s occur, usually with nonphasic, continuous forward flow; and 3) pathway diameters indexed to 3 square root of body surface area may be used as an output-independent parameter to cross-check Doppler data.
The distribution and synthetic rate of glomerular basement membrane components was examined in the Passive Heymann Nephritis model of experimental membranous nephropathy. The extensive tissue injury that developed included subepithelial electron-dense deposits, podocyte foot process effacement, and expansion of the glomerular basement membrane. Levels of mRNA for type IV collagen, laminin, and fibronectin from isolated glomeruli was quantitated by slot-blot analysis and showed no change in experimental animals as compared to controls at either 1 week, 3 weeks, or 3 months after disease induction. Immunoelectron microscopy with gold-labeled anti-laminin IgG revealed no difference in the number of particles bound to the glomerular basement membrane of experimental animals and controls. Immunofluorescence with both type IV collagen antisera and anti-laminin antibody showed no difference in the intensity or pattern of staining. Despite extensive glomerular damage and glomerular basement membrane thickening, no evidence was found for either an increase in the synthetic rate of type IV collagen, laminin, or fibronectin or for an accumulation of basement membrane laminin within the damaged glomeruli. Alternate processes, such as diminished density of matrix components or accumulation of other unmeasured matrix constituents, presumably account for the expansion of the glomerular basement membrane seen in experimental membranous nephropathy.
Sixty-three angina patients were recruited to participate in a two-week, randomized, open-label, crossover, multicenter trial to compare patient acceptance of two transdermal nitroglycerin delivery systems, Minitran and Transderm-Nitro (TDN). Patients were enrolled if they had stable angina and had been on a stabilized dose (5, 10, or 15 mg/24 hr) of Nitro-Dur II (ND II) for at least one month before entering the study. Patients with a bias against TDN or with any of the contraindications for transdermal nitroglycerin therapy were excluded. During the two consecutive one-week treatment periods, the patients received their prestudy dose regimen of Minitran and TDN in random order. Patients completed daily diaries, weekly questionnaires, and poststudy patient preference evaluation forms. Of the 63 patients who completed the study, 70% preferred Minitran overall (P less than or equal to 0.001), 24% preferred TDN, and 6% had no overall preference.
To determine the correlation between electrocardiographic (ECG) findings and anatomy utilizing echocardiography in children with pressure- or volume-loaded left ventricles, we analyzed the preoperative ECG tracings of 19 patients who underwent surgery for significant aortic stenosis and 12 patients who underwent cardiac catheterization or surgery for clinically significant ventricular septal defects. We then compared them with a group of 21 normal controls. The left ventricular muscle mass in these patients was calculated from echocardiograms using the simplified cubed formula. Posterior and septal wall thickness and cavity size were significantly greater in the aortic stenosis group than in the normal group. Only cavity size was significantly greater in the ventricular septal defect group than in the normal group. Eighteen aortic stenosis patients (95%) and ten ventricular septal defect patients (83%) had a left ventricular muscle mass greater than 2 standard deviations above the mean for the normal group. Significant differences were found in the voltages of SV1 + RV6 and in the voltage of RV6 alone between normals, aortic stenosis patients, and ventricular septal defect patients regardless of age. Using conventional ECG criteria for left ventricular hypertrophy, the highest sensitivity in aortic stenosis patients (67%) and ventricular septal defect patients (60%) was modest. The likelihood ratio for a positive test in either group was the best for SV1 + RV6 > 98th centile for age; RV6 > 98th centile for age was the best single measurement. No correlation was found between voltage and any measurable hemodynamic or anatomic data. Conventional pediatric ECG criteria for left ventricular hypertrophy have only modest sensitivity regardless of whether the heart is under pressure or volume load. Because left ventricular muscle mass can be precisely determined by echocardiography, these ECG criteria should be applied cautiously.
With the advent of cardiac magnetic resonance imaging and high-resolution echocardiography, cardiac catheterization is unnecessary in clinical protocols in the "routine" single ventricle patient. Catheterization adds little to clinical care in these cases, and there are significant risks and costs associated with it. Catheterization should be reserved for cases in which noninvasive evaluations are equivocal, conflictory, demonstrate deterioration, or needed for intervention. This article delineates the role of noninvasive evaluations relative to cardiac catheterization in the routine single ventricle patient.
Magnetic resonance imaging (MRI) is a unique and insightful tool for the assessment of physiology and function in congenital heart disease, in both the preoperative and postoperative state. MRI can accurately measure the volume and mass of unusual ventricular shapes, perform myocardial tissue and blood tagging, and can measure velocity and flow using phase-encoded velocity mapping. This has added new dimensions to research in pediatric cardiology. Newer techniques such as oxygen-sensitive MRI and echo-planar MRI promise further advances in the field. This article describes contemporary MRI studies of the physiology of complex congenital heart disease.
The right ventricle is often subject to both pressure and volume overload in congenital heart disease. Evaluating right ventricular function in both the native lesion and after surgery in light of these loading conditions, presents a unique challenge for investigators studying these misshapen hearts. The purpose of this article is to briefly delineate what is generally known about right ventricular function in congenital heart disease and to touch on some noninvasive imaging modalities which have helped shed some light on this matter.
OBJECTIVES: The purpose of this study was to determine the diagnostic accuracy of fetal echocardiography in evaluating anatomic details of the single ventricle heart and the outcome of fetuses diagnosed with this anomaly. STUDY DESIGN: This is a retrospective study of 57 fetuses in which the results of fetal echocardiography were compared with the diagnoses at postnatal echocardiography, and postnatal surgical outcome was reviewed. RESULTS: Diagnostic accuracy was present in predicting morphology of the predominant ventricle, visceral situs, presence of pulmonary or aortic outflow tract obstruction, and presence of obstructed pulmonary venous outflow (sensitivity 100%). However, the ability to predict for a ductal dependent pulmonary circulation was poor (sensitivity 63%). Errors were made in the fetal assessment of ventricular size and viability such that in three cases, postnatal plans were altered toward a two-ventricular intervention. Of the 57 fetuses, intervention was elected in 37 (75%). Termination or nonintervention was elected in 14, and and 6 died before intervention. Of those operated on, 71% are presently alive after various stages of intervention. CONCLUSIONS: Accurate diagnosis of the fetal single ventricle heart is possible, and outcome is improving. Caution must be used in judging ventricular size and in predicting ductal dependent pulmonary circulation.