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Biomedical subjects

C E Clark

Publications and source records attributed to C E Clark.

At least 19 recordsLinked to original sources

Thoracolumbar osteotomy for postsurgical sagittal imbalance.

A prospective study of 12 patients with sagittal plane imbalance after multiple surgeries for scoliosis is reported. Reconstruction was attempted by posterior thoracolumbar junction osteotomy. Eighty-seven degrees of thoracic kyphosis (ending at L3) was improved to forty-one degrees (ending at T12). Lumbar lordosis was increased from 21 to 30 degrees, beginning at L1 afterward (L3 before). 8.7 cm posterior displacement of the sagittal weight-bearing axis was achieved. No permanent complications ensued. The procedure, without anterior surgery, corrects the deformity at the apical area. Cotrel-Dubousset instrumentation secured correction and fixation.

Adult

Prevention of the crankshaft phenomenon.

Factors favoring development of the crankshaft phenomenon after posterior spinal fusion include immaturity and large residual deformity. Eight patients at high risk to develop the crankshaft phenomenon underwent periapical anterior growth arrest and fusion before posterior instrumentation and fusion. With follow-up to skeletal maturity, 0% developed crankshaft phenomenon. Anterior growth arrest and fusion before a posterior procedure is recommended in scoliosis patients at high risk to develop the crankshaft phenomenon.

Child

Fusion levels and hook patterns in thoracic scoliosis with Cotrel-Dubousset instrumentation.

This study reports the results of treatment of adolescents with King Types 2, 3, and 4 idiopathic curves using Cotrel-Dubousset instrumentation. Imbalance was seen in Types 2 and 4 curves when distraction direction hook patterns crossing the thoracolumbar junction were employed. Imbalance was not seen when a modified hook pattern employing compressing forces across the thoracolumbar junction was employed. No imbalance was observed in Type 3 curves using the basic right thoracic curve hook pattern. In Type 4 curves, a second modified hook pattern is required to obtain improved correction and balance. The mechanism of production of imbalance is explained by a three dimensional analysis of the deformity and of the forces generated by the Cotrel-Dubousset system.

Adolescent

Cotrel-Dubousset instrumentation.

Cotrel-Dubousset Instrumentation (CDI) presents a diversified posterior implant system applicable in any situation requiring posterior spinal instrumentation. It acts in the three dimensions of the spine, frontal-sagittal-axial. Correct hook site selection and direction provide spinal balance in three dimensions. The double major idiopathic scoliosis is an appropriate model on which to learn the principles of usage of CDI Results of CDI in a wide variety of spinal pathology have been excellent. There is a learning curve for CDI, hook placement being the most significant. Pitfalls and complications can be avoided.

Bone Screws

Abnormal right ventricular size and ventricular septal motion after atrial septal defect closure: etiology and functional significance.

Postoperative echocardiogram often demonstrate persistent right ventricular dilatation and paradoxic ventricular septal motion after repair of an atrial septal defect. To determine the prevalence, causes and significance of these echocardiographic abnormalities, 31 patients were studied with catheterization and echocardiography before and after repair of an atrial septal defect. Before operation, every patient manifested right ventricular dilatation, and all but one had abnormal septal motion. After operation, right ventricular dilatation was noted in 24 (77%) and abnormal septal motion in 21 (68%) patients despite the absence of residual left to right shunting in 30 (97%). These echocardiographic abnormalities could be correlated with age at operation and length of postoperative follow-up study but did not correlate with the degree of preoperative right ventricular enlargement or with shunt size or right ventricular pressure before or after operation. There was no associated functional deficit as demonstrated by the normal maximal oxygen consumption in all 13 patients who underwent treadmill exercise testing 5 to 38 months after operation; these patients included 9 with persistent right ventricular enlargement and abnormal septal motion.

Adolescent

Prevalence and characteristics of disproportionate ventricular septal thickening in patients with coronary artery disease.

Echocardiographic or necropsy studies were performed in 151 patients with coronary artery disease. Prevalence of disproportionate septal thickening (septal to free wall ratio greater than or equal to 1.3) was 11%. An abnormally increased septal-free wall ratio in these patients had two principal etiologies. First, it was a manifestation of genetically transmitted hypertrophic cardiomyopathy, as evidenced by disproportionate septal thickening in first degree relatives. Second, it was due to disproportionate septal thickening which did not appear to be a manifestation of genetically transmitted hypertrophic cardiomyopathy. This latter conclusion was suggested by negative echocardiographic studies in some families of patients with both coronary artery disease and disproportionate septal thickening. In addition, numerous disorganized cardiac muscle cells, characteristically present in patients with genetically transmitted hypertrophic cardiomyopathy, were absent from the septum of all patients with disproportionate septal thickening studied at necropsy. Although the mechanism responsible for this secondary type of disproportionate septal thickening is unknown, our results indicate that the presence of disproportionate septal thickening in a patient with coronary artery disease does not, per se, indicate the coexistence of genetically transmitted hypertrophic cardiomyopathy.

Coronary Disease

Electrocardiographic findings in patients with obstructive and nonobstructive hypertrophic cardiomyopathy.

One hundred and thiry-four patients with hypertrophic cardiomyopathy were evaluated by standard 12-lead electrocardiography. Normal electrocardiograms were extremely uncommon, occurring in less than 7% of each subgroup of patients (i.e., those with or without either symptoms or obstruction to left ventricular outflow), with the exception of those who were both asymptomatic and had no left ventricular outflow obstruction. Even in this subgroup, however, normal electrocardiograms occurred in only 27% of patients. Repolarization abnormalities and left ventricular hypertrophy were the most common abnormalities, occurring in 81% and 62%, respectively, of the total population. A broad spectrum of other electrocardiographic abnormalities was found, but none was unique to hypertrophic cardiomyopathy. Patients with vs those without electrocardiographic left ventricular hypertrophy or left atrial abnormality had significantly (P less than 0.005) greater mean ventricular septal thickness (22 +/- 0.6 vs 19 +/- 0.6 mm) and left atrial dimension (48 +/- 1 vs 40 +/- 1 mm) measured by echocardiography, and signficantly (P less than 0.01) higher mean pulmonary capillary wedge pressure (16 +/- 1 vs 10 +/- 1 mm Hg) and left ventricular end-diastolic pressure (20 +/- 1 vs 15 +/- 1 mm Hg). The high prevalence and diverse nature of electrocardiographic abnormalities suggest that any patient with an unusual and unexplained electrocardiogram should be suspected of having hypertrophic cardiomyopathy even if the physical examination is normal, as is often the case in patients without obstruction.

Cardiomyopathy, Hypertrophic

Cytogenetic abnormalities in orthopedic patients.

Patients with orthopedic problems may also have chromosomal abnormalities. Individuals who present with subtle clinical findings suggestive of a known syndrome resulting from a chromosomal abnormality, such as Klinefelter syndrome, Turner syndrome, or any of the known trisomiers, should be investigated further in order to confirm the diagnosis. In addition, those patients who have multiple congenital abnormalities in several systems should also have chromosome analysis. This should be done not only to gain new information in regard to chromosome abnormalities, but also to establish a diagnosis for the individual and thus provide proper genetic counseling for the family. If the clinical picture strongly suggests a chromosomal abnormality, and routine karyotyping does not demonstrate one, it is imperative that one or more banding techniques be utilized before a chromosomal abnormality can be ruled out.

Abnormalities, Multiple

Sudden infant death syndrome (SIDS). Echocardiographic studies in relatives of infants with SIDS.

Echocardiographic studies were performed in 42 sets of parents who had at least one infant with Sudden Infant Death Syndrome (SIDS). Asymmetric septal hypertrophy (ASH) was detected by echocardiography in one member of only 5 percent of the 42 sets of parents. Echocardiograms were also obtained in three other sets of parents who had infants with SIDS (selected because their infants showed small foci of disorganized cardiac muscle cells in the ventricular septum, similar to those present in patients with typical ASH but less marked in severity). ASH was present in one member of each of these three sets of parents. Ventricular septal-to-posterobasal left ventricular wall thickness ratios in the five subjects in this study with echocardiographically determined ASH ranged from 1.3 to 1.7, although only one individual showed marked thickening of the ventricular septum (22 mm). Thus, SIDS and ASH do not appear to be commonly associated conditions.

Cardiomyopathy, Hypertrophic

Prevalence and characteristics of disproportionate ventricular septal thickening in patients with acquired or congenital heart diseases: echocardiographic and morphologic findings.

Echocardiographic and necropsy studies were performed in 304 patients with various cardiac diseases. The overall prevalence of disproportionate ventricular septal thickening (septal to free wall ratio greater than or equal to 1.3) was 10%. However, it was related to the type of cardiac lesion. Prevalence was high (greater than 20%) in pulmonary stenosis or primary pulmonary hypertension, lower (less than 15%) in Eisenmenger syndrome or aortic or mitral valvular disease and was not present in atrial or ventricular septal defect. In right ventricular overload, prevalence of disproportionate septal thickening correlated with increasing ventricular systolic pressure. None of 16 patients with disproportionate septal thickening studied at necropsy showed marked disorientation of cardiac muscle cells in the ventricular septum, characteristic of genetically transmitted asymmetric septal hypertrophy (ASH). Furthermore, disproportionate septal thickening was demonstrated by echocardiography in only one of 59 first degree relatives of patients with disproportionate septal thickening and associated cardiac diseases. Thus, disproportionate ventricular septal thickening associated with other cardiac diseases usually is due to secondary hypertrophy and is not a manifestation of genetically transmitted ASH.

Adolescent

Asymetric septal hypertrophy in childhood.

Although considerable information is available concerning the clinical features and natural history of asymmetric septal hypertrophy (ASH) in adults, little is known of this disease in children. The clinical characteristics and course of 46 children with ASH, who were evaluated at the National Heart and Lung Institute, have been analyzed. Twenty-four children had obstruction to ventricular outflow; 22 children had no obstruction to ventricular outflow, including 11 patients without overt manifestations of cardiac disease other than echocardiographic evidence of ASH. Thirty-five of the 46 children have been followed for one to 16 years (average 7.4 years). These latter children represent that subgroup of patients with ASH referred to the National Heart and Lung Institute and diagnosed prior to the general availability of echocardiography. The clinical course of these patients was variable. Fourteen (40%) of the 35 patients improved or remained stable, including four patients who received propranolol. Ten (29%) of the 35 patients deteriorated clinically and 11 (31%) of the 35 patients died suddenly (4% mortality per year). Two of the patients who died suddenly had previously undergone operation (six and 13 years previously) with resultant abolition of the outflow gradient; four others were taking propranolol. Neither symptomatology, electrocardiographic abnormalities, heart size, left ventricular ejection or upstroke time, magnitude of outflow gradient, or left ventricular end-diastolic pressure proved predictive of sudden death. Excluding patients who had previous operation, eight (40%) of 20 patients with obstruction who were followed long term and one (9%) of 11 patients without outflow obstruction died suddenly. Thus, the clinical and hemodynamic spectrum of ASH in childhood is broad. However, deterioration in clinical condition or sudden death has been relatively common in children with overt signs of cardiac disease.

Adolescent