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Biomedical subjects

S Y Ho

Publications and source records attributed to S Y Ho.

At least 55 records · Page 3Linked to original sources
PubMed2000

Severe airflow limitation after the unifocalization procedure: clinical and morphological correlates.

BACKGROUND: While unifocalization techniques have improved the treatment options in patients with pulmonary atresia, ventricular septal defect (PA-VSD), and major aortopulmonary collaterals (MAPCAs), severe airflow limitation contributes to significant early postoperative morbidity and mortality. Although this has been attributed to bronchospasm, characteristically it is refractory to bronchodilators, suggesting that other mechanisms may play a role. METHODS AND RESULTS: The clinical course and preoperative angiograms of patients who underwent unifocalization were reviewed. Patients who developed airflow limitation early after surgery underwent fiberoptic bronchoscopy. In addition, the anatomy of the MAPCAs was examined in 14 heart-lung blocks from patients with PA-VSD. Twenty-two procedures were performed in 16 children. Three developed marked airflow limitation early after surgery, necessitating prolonged high-pressure ventilation. Bronchoscopy demonstrated tracheobronchial epithelial necrosis in 2 and signs of tracheobronchial ischemia in the third. Two were successfully extubated after 15 and 16 days, but the third died after 57 days of ventilatory support. Review of the preoperative angiograms demonstrated an extensive peribronchial arterial supply arising from a MAPCA in 1 of the patients who developed severe airway necrosis after unifocalization. This was also obvious in a second patient, but the MAPCA was not included in the unifocalization. In 7 autopsy specimens, MAPCAs contributed to a peribronchial or peritracheal vascular network. Dissection of the distribution of these branches in 2 specimens revealed extensive intrapulmonary peribronchial anastomoses. CONCLUSIONS: Airflow limitation early after unifocalization is related to airway ischemia resulting from interruption of the tracheobronchial blood supply during mobilization of MAPCAs.

Abnormalities, Multiple↗
PubMed2000

Anatomy of the human atrioventricular junctions revisited.

There have been suggestions made recently that our understanding of the atrioventricular junctions of the heart is less than adequate, with claims for several new findings concerning the arrangement of the ordinary working myocardium and the specialised pathways for atrioventricular conduction. In reality, these claims are grossly exaggerated. The structure and architecture of the pathways for conduction between the atrial and ventricular myocardium are exactly as described by Tawara nearly 100 years ago. The recent claims stem from a failure to assess histological findings in the light of criterions established by Monckeberg and Aschoff following a similar controversy in 1910. The atrioventricular junctions are the areas where the atrial myocardium inserts into, and is separated from, the base of the ventricular mass, apart from at the site of penetration of the specialised axis for atrioventricular conduction. There are two such junctions in the normal heart, surrounding the orifices of the mitral and tricuspid valves. The true septal area between the junctions is of very limited extent, being formed by the membranous septum. Posterior and inferior to this septal area, the atrial myocardium overlies the crest of the ventricular septum, with the atrial component being demarcated by the landmarks of the triangle of Koch. The adjacent structures, and in particular the so-called inferior pyramidal space, were accurately described by McAlpine (Heart and Coronary Arteries, 1975). Thus, again there is no need for revision of our understanding. The key to unravelling much of the alleged controversy is the recognition that, as indicated by Tawara, the atrioventricular node becomes the atrioventricular bundle at the point where the overall axis for conduction penetrates into the central fibrous body. There are also marked differences in arrangement, also described by Tawara, between the disposition of the conduction axis in man as compared to the dog.

Atrioventricular Node↗
PubMed2000

Anatomy of the muscular subpulmonary infundibulum with regard to the Ross procedure.

BACKGROUND: To clarify the precise anatomical relationship of the muscular subpulmonary infundibulum. METHODS: Eleven hearts were dissected, and microscopic sections taken through the arterial trunks of a 37-week-old fetus and of a neonate. The anatomy was also investigated during operative Ross procedures. RESULTS: The sinotubular junctions of the pulmonary and aortic roots cross obliquely. The leaflets of the pulmonary valve are lifted away from the ventricular septum by the free-standing subpulmonary infundibulum, whereas the aortic valve is deeply wedged between the atrioventricular junctions. The muscular infundibulum spirals around the aortic root, being longest below the right-facing aortic sinus and shortest below the left. The first septal perforating artery pierces the septum below the shortest part of the infundibulum, sometimes within a millimeter of the pulmonary valvar hinge, but a muscular sleeve lifts the pulmonary leaflets from the septal musculature. CONCLUSIONS: The pulmonary valvar leaflets are supported entirely by free-standing musculature, having no direct relationship with the ventricular septum. This makes possible the Ross procedure.

Adult↗
PubMed2000

Late ventricular structure after partial left ventriculectomy.

Nine months after partial ventriculectomy, a 53-year-old man died of progressive heart failure. His heart was examined to determine the alignment of the muscle fibers around the ventricular scar, which was 11 cm long, 1.3 cm thick and 4 cm wide. The scar reached 2 to 12 mm beyond the surgical suture line. The fibers in the middle and subendocardial layers were malaligned, resulting in convergence, compression and regional necrosis.

Cardiomyopathy, Alcoholic↗
PubMed2000

A unique case of ventricular isomerism?

Isomerism of the atria has often been described with various complex cardiac malformations. As far as is known, a case of 'ventricular isomerism' has never been recorded. Described is a specimen where, on the basis of morphological criterions, there are two right ventricles.

Aorta, Thoracic↗
PubMed2000

Isomeric arrangement of the left atrial appendages and visceral heterotaxy: two atypical cases.

We present two cases in which there was isomeric arrangement of the left atrial appendages in association with multiple spleens and complete heart block. In both of these, the venous connections were normal. In one case the arrangement of the bronchial tree and the lungs was normal, the liver was left-sided, and the stomach was right-sided. In the other case, there was left isomeric broncho-pulmonary morphology, and both liver and stomach were right-sided. These unusual combinations show the need for full description of the morphology of other organs, and the venoatrial connections, in cases with isomeric arrangement of the atrial appendages. They also demonstrate that connection of the inferior caval vein cannot be taken as a reliable marker of an atrium having a morphologically right appendage.

Abnormalities, Multiple↗
PubMed2000

Twisted atrioventricular connections in double inlet right ventricle: evaluation by magnetic resonance imaging.

Twisted atrioventricular connections occur almost exclusively in the hearts with biventricular atrioventricular connections. Only one example of double inlet left ventricle has been illustrated in which the axes of the two atrioventricular valves crossed each other. We describe herein three patients, and one autopsied specimen, with double inlet right ventricle in which magnetic resonance imaging clearly demonstrated twisted atrioventricular connections.

Child, Preschool↗
PubMed2000

Transthoracic three-dimensional echocardiography for the assessment of straddling tricuspid or mitral valves.

BACKGROUND: The advent of 3D echocardiography has provided a technique which, potentially, could afford significant additional information over conventional cross-sectional echocardiography in the assessment of patients with straddling atrioventricular valves prior to surgical correction. METHODS: Eight patients, aged from 1 month to 9.2 years, were examined with 3D echocardiography. All but three had discordant ventriculoarterial connections or double outlet right ventricle. Data suitable for reconstruction was acquired with transthoracic scanning. Right and left ventricular volumes were calculated in the 3D dataset. RESULTS: 3D echocardiography proved capable of defining the exact degree of straddling by imaging the proportion of tension apparatus attached to either side of the ventricular septum. It was able also to display the atrioventricular junction "en face", thus permitting identification of the precise site of insertion of the muscular ventricular septum relative to the atrioventricular junction. This made it possible first, to calculate the degree of valvar override, and second, to predict the location of the penetrating atrioventricular bundle. End-diastolic volume of the right ventricle in those with straddling tricuspid valves was 73 (61-83)% of normal, and, of the left ventricle in those with mitral valvar straddling 71 (40-97)% of normal. CONCLUSIONS: 3D echocardiography can aid in planning the optimal surgical procedure in patients with straddling or overrriding atrioventricular valves, as it provides diagnostic information superior to standard cross-sectional techniques. It also allows for exact measurement of the volumes of the respective ventricles.

Child↗
PubMed2000

Sudden death in a child with an unusual accessory connection.

An 8-year-old boy with Wolff-Parkinson-White syndrome died suddenly whilst exercising. He had been well with no immediate preceding symptoms of an arrhythmia, and was receiving no drugs. As an infant he had suffered recurrent episodes of atrioventricular reciprocating tachycardia (AVRT) and had documented pre-excited atrial fibrillation. At electrophysiological (EP) study, the refractory periods of his two accessory pathways were less than 220 ms. Drugs were discontinued at 4 years of age when he remained asymptomatic. Autopsy confirmed a very unusual accessory pathway. It was a muscular connection between the base of the right atrial appendage and the right ventricle, distant from the annulus of the tricuspid valve.

Child↗
PubMed2000

Documentation of variations in sinonasal anatomy by intraoperative nasal endoscopy.

OBJECTIVES: Functional endoscopic sinus surgery (FESS) requires a thorough understanding of the variability in sinonasal anatomy. Previous reports have relied primarily on anatomic studies of cadaveric specimens or skulls, or on radiographic analysis. Relatively few comparative anatomic data have been accumulated with endoscopic examination of living patients. STUDY DESIGN: Retrospective review of video recordings of 119 consecutive patients undergoing intraoperative nasal endoscopy at the time of sinonasal surgery. METHODS: At the beginning of each surgical procedure, endoscopic examination of the nasal cavities was performed with 0 degrees and 30 degrees telescopes and recorded with a three-chip video camera on 3/4-inch U-matic videotape. These video records were then reviewed with attention to variations in anatomical configuration of different sinonasal structures. RESULTS: Data demonstrating variations in the anatomical configuration of the following structures of the lateral nasal wall are presented. Middle turbinate: typical (63%), concha bullosa (15%), sagittal cleft (6%), laterally displaced (4%), "L" shaped (3%), medially bent (3%), laterally bent (3%), medially displaced (2%), and transverse cleft (0.5%). Uncinate process: typical (85%) and medially rotated (15%). Ethmoid bulla: typical or balloon (45%), sausage-shaped (34%), and flat (21%). Accessory ostium: round (50%), oval (46%), and kidney-shaped (4%). Sphenoid sinus ostium: oval (42%), slit (32%), and round (26%). The classification system for the anatomical categories is illustrated with digitized images. CONCLUSIONS: This study attempts to provide statistical data regarding variations in sinonasal anatomy in living subjects. Familiarity with such anatomy is important in differentiating normal variants from pathological conditions to optimize surgical treatment of sinus disease, while avoiding complications.

Adolescent↗
PubMed2000

How constant anatomically is the tendon of Todaro as a marker for the triangle of Koch?

INTRODUCTION: Although well recognized by anatomists as a border of the triangle of Koch demarcating the location of the AV node, the tendon of Todaro is not visible in the operating room or in the catheterization laboratory. Instead, clinicians use as surrogate a projected line between the eustachian valve and the central fibrous body. The constancy of the tendon of Todaro within this border remains to be determined. MATERIALS AND RESULTS: We reexamined serial histologic sections from 25 adults and 50 infants and gross dissections in four normal hearts. The tendon of Todaro was identified in all cases and traced to the central fibrous body in all but one case. It tended to be thicker in the hearts of infants cases (0.2 to 0.8 mm vs 0.1 to 0.6 mm). The tendon and the hinge-line of the septal leaflet of the tricuspid valve were consistent as landmarks for location of the compact AV node in all the cases studied by histology. Gross dissections traced the tendon to the free edge of the eustachian valve. CONCLUSION: The tendon of Todaro is present in hearts obtained from both adults and infants. It, or its surrogate, is a reliable border for the triangle of Koch and serves as a landmark to location of the atrial components of the AV conduction axis.

Adolescent↗
PubMed2000

Coronary arterial origins in transposition of the great arteries: factors that affect outcome. A morphological and clinical study.

OBJECTIVE: Transfer of the coronary arteries is crucial during the arterial switch operation for transposition, but little attention has been paid to the position of their orifices relative to the valvar sinuses. The objective of this study was to determine the factors which are important for effective transfer and to determine potential surgical significance. DESIGN: Morphological and clinical study. SETTING: Two national centres for neonatal cardiac surgery. PATIENTS: 277 patients with transposition of the great arteries. One group comprised 88 necropsy specimens (ages ranging from 17 weeks of fetal life to 17 years old), and the other comprised 189 children undergoing surgery. The coronary artery orifices were inspected relative to the depth of the aortic sinuses (vertical origin), relative to the commissures between the valvar leaflets (radial origin), and their angle of exit from the aortic wall (angle of origin). The data were compared with the surgical results. RESULTS: In the necropsy specimens, the vertical origin of the arteries was at, or above, the sinutubular junction in 20%, the radial origin was paracommissural in 3%, and the angle of origin was not orthogonal in 7%. Those with high take off and paracommissural origin were all intramural. In the clinical cases, those children with high take off, paracommissural origin or tangential origin had an increased risk at surgery. CONCLUSIONS: In 20% of hearts, high take off, paracommissural orifice, or tangential origin of coronary arteries is found. This may be recognised preoperatively by echocardiography and may cause technical difficulty in transfer during the arterial switch procedure.

Child↗
PubMed2000

The atrioventricular junctions in Ebstein malformation.

OBJECTIVE: To review the anatomical structure of the right atrioventricular junction, including the specialised atrioventricular conduction system, in hearts with Ebstein's malformation, to identify potential substrates for the abnormalities in conduction. METHODS: Five heart specimens representing the morphological spectrum of Ebstein malformation were examined grossly and histologically. RESULTS: On the endocardial surface, the atrioventricular junction was marked by a faint line in two hearts, and by a small ridge in the other three. Analysis of the right parietal junction in four hearts revealed only two accessory muscular atrioventricular connections. A plane of fibrofatty tissue separated atrial from ventricular myocardium in the right parietal junction in all hearts. The compact atrioventricular node was closer to the coronary sinus than usual. Accessory nodoventricular connections were present in four hearts, while accessory fasciculo-ventricular connections were found in one. The right bundle branch was hypoplastic or absent in four hearts. CONCLUSIONS: In this small series, the parietal atrioventricular junction was better developed than previously thought. Structural abnormalities of the atrioventricular conduction system, however, were present. These may account for some of the conduction abnormalities frequently observed with the Ebstein malformation.

Atrioventricular Node↗
PubMed2000

Attitudes and attraction: a new test of the attraction, repulsion and similarity-dissimilarity asymmetry hypotheses.

Dissimilarity and similarity between attitudes of the participants and a stranger were manipulated across two sets of issues to test the attraction, repulsion and similarity-dissimilarity asymmetry hypotheses. Participants (N = 192) judged social (liking, enjoyment of company) and intellectual (intelligence, general knowledge) attractiveness of the stranger. The similarity in the first set of attitudes x similarity in the second set of attitudes effect emerged in social attraction, but not in intellectual attraction. Stated simply, dissimilarity had a greater weight than similarity in social attraction, but equal weight in intellectual attraction. These results support the similarity-dissimilarity asymmetry hypothesis that predicts dissimilarity-repulsion to be stronger than similarity-attraction. However, they reject (1) the attraction hypothesis that dissimilarity and similarity produce equal and opposite effects on social attraction; and (2) the repulsion hypothesis that only dissimilar attitudes affect social attraction by leading to repulsion. An equal weighting of dissimilarity and similarity in intellectual attraction further suggested that the similarity-dissimilarity asymmetry on social attraction is reflective of a stronger avoidance response in the Darwinian sense.

Adolescent↗
PubMed1999

Angiographic anatomy of the inferior right atrial isthmus in patients with and without history of common atrial flutter.

BACKGROUND: Although most ablative procedures undertaken for common atrial flutter target the inferior right atrial isthmus, comparative studies of the morphology of this area are lacking. Our study examines its angiographic anatomy, making correlations with postmortem specimens, to provide a better understanding of the anatomic substrate of this arrhythmia. METHODS AND RESULTS: The gross morphological features and dimensions of the area between the orifice of the inferior caval vein and the attachment of the septal leaflet of the tricuspid valve were determined from angiograms made in 23 patients with documented atrial flutter and 30 control subjects. For comparison, we studied 20 normal heart specimens. When viewed in right anterior oblique projection, 2 morphologically distinct areas were identified. In the specimens, the inferior isthmus measured a mean length of 30+/-4 mm, not significantly different from the dimensions obtained from angiograms of control subjects. The mean length of the isthmus, however, was greater in patients with common atrial flutter than those without (37+/-8 versus 28+/-6 mm). Patients with atrial flutter and structural heart disease had an even longer isthmus than those with flutter alone (39. 6+/-8 versus 33+/-7 mm). Compared with those without flutter, the atrial diameter was also larger in patients with flutter (57.6+/-9 versus 48.5+/-6 mm). Reevaluation carried out at follow-up 10+/-2 months after ablation did not show any reduction in atrial size, although contractility improved. CONCLUSIONS: The inferior isthmus and right atrium in patients with common atrial flutter were significantly larger than those in a control population.

Adult↗