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Biomedical subjects

A J Chin

Publications and source records attributed to A J Chin.

At least 37 records · Page 2Linked to original sources
PubMed1993

Semiquantitative assessment of mitral regurgitation by Doppler color flow imaging in patients aged < 20 years.

Doppler color flow imaging is a rapid, noninvasive method to estimate the severity of mitral regurgitation (MR) in adult patients; theoretically, it should be possible to use the technique at least as successfully in infants and children, because problems with beam penetration should be diminished. Doppler color flow studies in 27 pediatric patients (age range 12 days to 17 years, median 7 months) with various degrees of MR (but without coexistent aortic regurgitation or intracardiac shunt) were analyzed. All patients underwent left ventriculography within 2 weeks of their color Doppler examination. Three sets of parameters were investigated, including: (1) maximal length of regurgitant jet: by itself, and indexed to cube root of body surface area (BSA) and to left atrial depth; (2) proximal width of jet; by itself, and indexed to cube root of BSA and to diameter of mitral annulus; and (3) regurgitant jet area (RJA): by itself, and indexed to BSA and left atrial area (LAA). Of these parameters, RJA indexed to BSA, and the ratio of RJA/LAA had the best correlation with angiographic grading (r = 0.84 and 0.92, respectively). With our instrumentation, the "cutoff" values in infants and children separating mild, moderate and severe MR appear to be 4 and 10 cm2/m2 for RJA/BSA, and 30 and 50% for RJA/LAA, respectively. Both inter- and intraobserver correlations were good for RJA (r = 0.95 and 0.94, respectively), and the ratio of RJA/LAA (r = 0.92 and 0.94, respectively). Semiquantitative assessment of MR appears to be possible in pediatric patients, using 1 instrument and a standardized technique.

Adolescent↗
PubMed1993

Noninvasive diagnosis of coarctation of the aorta in the presence of a patent ductus arteriosus.

Although the diagnosis of coarctation of the aorta in the full-term neonate is straightforward when no ductus arteriosus is present, identification of coarctation of the aorta when a ductus arteriosus is patent can be difficult. A patent ductus arteriosus is frequently found in association with coarctation of the aorta, and it may remain open for many days. Thus a reliable method to rapidly identify coarctation of the aorta would obviate the need for cardiac catheterization or an in-hospital observation period until the ductus arteriosus closes spontaneously. Echocardiographic/Doppler examination of 19 consecutive full-term neonates with a birth weight of > 2.9 kg, who subsequently underwent surgical repair of coarctation of the aorta, were reviewed. Fourteen patients with similar weights, a patent ductus arteriosus, and a normal aortic arch were matched for comparison. Based on the findings, the following diagnostic criteria for coarctation of the aorta are suggested: isthmic diameter less than or equal to 3 mm or isthmus equal to 4 mm together with the Doppler finding of continuous antegrade flow in the isthmal segment. Coarctation of the aorta in the full-term neonate can be ruled out when the flow within the ductus arteriosus is exclusively from aorta to pulmonary artery or when the isthmic diameter is equal to or greater than 5 mm.

Aorta, Thoracic↗
PubMed1993

Changes in ventricular geometry early after Fontan operation.

Acute removal of a ventricular volume overload, in the face of relatively unchanging ventricular mass, results in geometric alterations that can impair diastolic ventricular performance after Fontan operation. We investigated whether geometric alterations were (1) more severe after Fontan operation than after hemi-Fontan operation, (2) more severe in infants than in children, and (3) more severe in the morphologic right ventricle than in the morphologic left ventricle. We studied 22 patients, 11 with hypoplastic left heart syndrome and 11 with a functionally single morphologic left ventricle. After Fontan operation, right ventricular end-diastolic volume declined by 52% from 36.6 +/- 12.2 to 17.5 +/- 9.3 mL. Right ventricular wall thickness increased from 6.8 +/- 1.3 to 7.5 +/- 1.8 mm. Left ventricular end-diastolic volume diminished by 40% from 57.6 +/- 23.3 to 34.8 +/- 17.6 mL. Left ventricular wall thickness increased from 7.0 +/- 2.1 to 8.7 +/- 1.9 mm. The alterations in right ventricular geometry are more marked early after Fontan operation than early after the hemi-Fontan procedure. Geometric alterations in the left ventricle appear to be more severe in infants than in children. Finally, alterations in the morphologic right ventricle appear to be of similar magnitude to those in the morphologic left ventricle.

Body Surface Area↗
PubMed1993

Changes in right ventricular geometry and heart rate early after hemi-Fontan procedure.

To document and quantitate changes in right ventricular (RV) geometry and heart rate, we prospectively examined 35 consecutive patients with hypoplastic left heart syndrome under steady-state conditions (chloral hydrate sedation) before and after a bidirectional cavopulmonary anastomosis (hemi-Fontan) procedure. Right ventricular end-diastolic volume (RVEDV) was calculated as the product of RV cavity areas in two orthogonal planes divided by RV maximal length in either plane. After the hemi-Fontan procedure, RVEDV decreased by 33% from 33 +/- 13 to 22 +/- 11 mL (mean +/- standard deviation). Indexed RVEDV decreased from 86 +/- 37 to 57 +/- 28 mL/m2. The RV wall thickness at the diaphragm in subcostal frontal view (RVWD) increased by only 11% from 8 +/- 0.2 to 9 +/- 0.2 mm (p = not significant), but RVWD/RVEDV increased by 111% from 0.36 +/- 0.22 to 0.76 +/- 0.69 mm/mL (p = 0.002). The RV anterior wall thickness in subcostal sagittal view (RVWA) increased by only 13% from 7 +/- 0.2 to 8 +/- 0.2 mm (p = not significant), but RVWA/RVEDV increased by 103% from 0.31 +/- 0.20 to 0.63 +/- 0.54 mm/mL (p = 0.002). In 11 of 35 patients (31%), resting heart rate did not change (118 +/- 14 versus 108 +/- 9 beats/min; p = not significant); however, in 24 of 35 patients (69%), heart rate increased significantly (108 +/- 9 versus 127 +/- 10 beats/min; p = 0.05). In conclusion, RV wall thickness is high before the hemi-Fontan procedure and increases slightly in the first postoperative week.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗
PubMed1993

Analysis of factors contributing to success in a program of micromanipulation-assisted fertilization.

OBJECTIVE: To determine factors important to clinical success in micromanipulation-assisted in vitro fertilization (IVF). DESIGN: Procedures invoked in two separate series of micromanipulation-assisted IVF cycles, one unsuccessful (series I) and the other successful (series II), were compared in an effort to identify changes that led to clinical success. SETTING: University-based IVF clinic. PATIENTS: In both IVF series involving micromanipulation, patients consisted of infertile couples who fit any of five categories of male-factor related infertility. The female patients underwent controlled hyperstimulation for oocyte retrieval and the oocytes were inseminated normally or were subjected either to partial zona dissection or subzonal sperm insertion to assist fertilization. Results in all groups were compared between the two patient series. RESULTS: In the successful series II, a noticeable improvement in fertilization rate and embryo quality was observed compared with series I. A significant increase in the percentage of patients reaching embryo transfer, the pregnancy rate per transfer, and the pregnancy rate per retrieval were noted in series II; a 25% ongoing pregnancy rate per retrieval was observed overall in this successful group, with "ongoing" defined as manifestation of at least a fetal sac on ultrasound with no detectable problems. Patients with a mixed transfer of embryos derived from manipulated and normally inseminated oocytes had a 75% rate of pregnancy per transfer in series II. Differences between the two series could not be attributed to patient selection or biases in selection of oocytes relegated to micromanipulation. However, oocyte handling, micromanipulation, and culture protocols differed significantly between the two series in that temperature and pH of oocytes was better controlled, and micromanipulation time was minimized in series II. CONCLUSION: Success in micromanipulation depends on maintenance of the oocyte in a stable and supportive environment throughout the micromanipulation procedure. It is also important to minimize trauma to the eggs by performing micromanipulation rapidly and with minimal distortion of the egg. Patients with a poor fertilization rate in standard IVF may experience a substantial increase in the likelihood of pregnancy when micromanipulation-assisted fertilization is performed on some eggs.

Cleavage Stage, Ovum↗
PubMed1992

Patterns of anomalous pulmonary venous connection/drainage in hypoplastic left heart syndrome: diagnostic role of Doppler color flow mapping and surgical implications.

Differentiation between anomalous connection and anomalous drainage of the pulmonary veins in hypoplastic left heart syndrome is important before either the Norwood procedure or heart transplantation is performed. To determine the prevalence of echocardiographically detected anomalous connection or drainage, or both, of pulmonary veins in patients with this syndrome, preoperative two-dimensional echocardiographic and Doppler color flow mapping studies of 317 patients who underwent the stage I Norwood procedure were reviewed. The term "connection" was used to describe the precise anatomic attachment of the pulmonary veins and the term "drainage" to describe the physiologic end point of pulmonary venous flow. Twenty patients (6.3%) had anomalous connection or drainage, or both, of the pulmonary veins by preoperative echocardiographic and Doppler examination. The subcostal and suprasternal scans best showed the anatomic details of the pulmonary veins. All these patterns were confirmed intraoperatively and could be grouped as follows: 1) partial anomalous connection and drainage (two patients); 2) total anomalous connection and drainage (eight patients); 3) normal connection with total anomalous drainage (eight patients); and 4) normal connection with partial anomalous drainage (two patients). The advantage of adding Doppler color flow mapping to two-dimensional echocardiography and conventional Doppler study was clearly demonstrated in the detection of small accessory vertical veins, their course and the presence or absence of obstruction. Doppler color flow mapping was especially helpful in detecting anomalous drainage of the right pulmonary veins to the right of the superior attachment of the septum primum.

Anastomosis, Surgical↗
PubMed1992

Imaging of pulmonary venous pathway obstruction in patients after the modified Fontan procedure.

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.

Cardiac Surgical Procedures↗
PubMed1991

Surgical management of severe aortic outflow obstruction in lesions other than the hypoplastic left heart syndrome: use of a pulmonary artery to aorta anastomosis.

Between December 1985 and April 1990, 50 infants with a variety of congenital cardiac lesions other than the hypoplastic left heart syndrome underwent surgical relief of aortic outflow obstruction by creation of a pulmonary artery to aorta anastomosis. The patients were grouped anatomically by ventriculoarterial alignment. Nineteen had normally aligned great arteries (group I); 25 had transposition of the great arteries, all with a univentricular heart of left ventricular morphology (group II); and 6 had a double-outlet right ventricle (group III). All patients had either aortic stenosis with atresia, subaortic stenosis or a restrictive ventricular septal defect. Sixteen had normal arch anatomy; 34 had arch anomalies consisting of arch hypoplasia (n = 17), coarctation (n = 11), interruption of the arch (n = 4) and complex arch anomalies (n = 2). Surgery was performed at a median age of 10 days (range 2 to 184). Of the 50 infants, 33 survived. No significant difference in early survival (30 days) was noted among the groups of varying ventriculoarterial alignment (68% group I, 72% group II, 83% group III) (p greater than 0.05). Overall actuarial survival was 63% at 18 months. Analysis of actuarial survival by arch anatomy, although not statistically significant, revealed a trend toward better survival at 18 months postoperatively in infants with normal arch anatomy (81%) than in infants with arch anomalies (54%). Of the 33 survivors, 26 have proceeded to the next surgical stage, including the Fontan procedure in 8, superior cavopulmonary anastomosis in 13 and biventricular repair in 5.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1991

Doppler color flow mapping assessment of residual shunt after closure of large ventricular septal defects.

Of 179 consecutive patients who underwent closure of a large ventricular septal defect (VSD) as part of reparative surgery under 2 years of age, 19 died early and 160 had echocardiographic evaluation that included Doppler color flow mapping at 8 +/- 7 days after repair. Sixty-one (38%) of patients had evidence of residual shunting in the peripatch area. Two independent observers measured the Doppler color jet width at the left septal surface; jet width was correlated with subsequent reoperation for residual VSD. Patients were divided into two groups by jet width measurement: group 1 measured 4 mm or greater (n = 4), and group 2 measured less than 4 mm (n = 57). Of the group 1 patients, three returned to the operating room for a large residual defect; one patient died without reoperation but was confirmed to have had a large defect by angiography. Four patients in group 2 underwent surgery for a residual VSD; two underwent reoperation for reasons other than a residual VSD and had closure of a small residual VSD; one patient thought to have a large residual VSD at reoperation was noted to have multiple muscular VSD and only a small residual VSD; and one patient had a small defect initially but returned 2 years later with late patch dehiscence. Sixty-five percent of 23 group 2 patients reevaluated at a mean of 10 +/- 8 months after initial study no longer showed evidence of residual shunting. Residual Doppler color jets are frequently noted after repair of a large VSD.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗
PubMed1990

Subcostal two-dimensional echocardiographic identification of anomalous attachment of septum primum in patients with left atrioventricular valve underdevelopment.

Five variations of atrial septal morphology occur in hypoplastic left heart syndrome. One variety, termed anomalous attachment of septum primum, has been described only in necropsy series. Two-dimensional echocardiography was utilized to determine the incidence of this anomaly in patients with left atrioventricular (AV) valve underdevelopment, including those with other ventriculoarterial alignments, such as transposition of the great arteries. Forty-eight (37%) of 129 patients with normally aligned great arteries (and two ventricles) had anomalous attachment of septum primum. Ten (34%) of 29 patients with double outlet right ventricle and left AV valve underdevelopment had this anomaly. Four (50%) of eight patients with single ventricle exhibited this atrial septal variant. The most reliable view to identify anomalous attachment was the subcostal left oblique-equivalent cut. Recognition of atrial septal morphology has implications for preoperative and intraoperative management of patients with left AV valve underdevelopment. The similar prevalence of this atrial septal variant in patients with normally aligned great arteries, double outlet right ventricle and transposed great arteries suggests that there may be a common mechanism for left AV valve underdevelopment that is independent of the development of the arterial portion of the heart.

Echocardiography↗
PubMed1990

Absent aortic valve: a complex anomaly.

Seven patients (four previously cited and three new cases) with absent aortic valve cusps (leaflets), a rare and underrecognized complex congenital heart defect, are discussed. All patients were male, six full-term and one premature with nonimmunologic hydrops. None underwent operation; all died within the first week of life from low cardiac output and hypoxemia. In most instances, the only remnant of the aortic valve was a nonobstructive fibrous ridge; occasionally, it was accompanied by rudimentary leaflets or sinuses of Valsalva. Absent aortic valve was associated with other significant structural malformations in all instances, including atrioventricular valve atresia, hypoplasia or dysplasia, less commonly double outlet right ventricle, abnormal pulmonary venous connection, or left ventricular endomyocardial abnormalities. Recognition of this unusual lesion is important since it is associated with other complex malformations, causes hypoxemia (for which early positive pressure ventilation is indicated), and could be possibly palliated using the right ventricle as the systemic ventricle.

Aortic Valve↗
PubMed1990

Prospective detection by Doppler color flow imaging of additional defects in infants with a large ventricular septal defect.

The use of Doppler color flow imaging and axial contrast angiography in the preoperative detection of additional ventricular septal defects (in the setting of a known large defect) were compared in a prospective fashion. One hundred seventy-nine infants with two ventricles (each of at least normal size) and a large, nonrestrictive ventricular septal defect underwent reparative surgery before 2 years of age. The reference standard for the presence of additional defects was intraoperative verification or (in cases in which the surgeon did not visualize any additional defect) subsequent identification at postoperative angiography, postoperative color Doppler examination or reoperation. Only six patients (3%) had additional ventricular septal defects confirmed at the time of repair; an additional five (3%) had defects found only postoperatively. The negative predictive value of Doppler color flow imaging and angiography was 0.95 (168 of 176) and 0.97 (168 of 174), respectively. The sensitivity was 0.27 (3 of 11) and 0.45 (5 of 11), respectively. For certain malformations with a very low prevalence of additional muscular defects (such as perimembranous ventricular septal defect with normally aligned great arteries), a clinical trial of reparative surgery without prior invasive study appears reasonable.

Angiography↗
PubMed1990

Ultrasonographic display of complex vascular rings.

Ultrasonographic display of vascular ring anatomy has been limited to single-plane views. This does not readily allow for a three-dimensional interpretation of structural relations. A method that included a sweep consisting of multiple contiguous frontal planes was used in 12 patients with a vascular ring before repair for the evaluation of the arch sidedness and number, brachiocephalic vessel pattern, upper descending thoracic aorta sidedness, ductus arteriosus site or sites and proximal pulmonary arteries; 7 patients had Doppler color flow imaging. Complete imaging of the luminal vascular components was possible in all but one patient. In four other patients, atretic segments of the vascular ring could not be displayed. The addition of Doppler color flow imaging especially aided in the tracing of multiple vascular structures in complex cases and in assessing ductus arteriosus and arch patency. The use of a suprasternal frontal sweep with posterior angulation could display encirclement of the air-filled trachea. Vascular ring segments without lumens could not be displayed.

Aorta, Thoracic↗
PubMed1990

Accuracy of prospective two-dimensional/Doppler echocardiography in the assessment of reparative surgery.

Between January 1987 and January 1989, all 129 patients (aged 11 days to 25 years, median 39 months) undergoing both an echocardiographic examination and cardiac catheterization after reparative surgery were prospectively included in a study to assess the accuracy of combined two-dimensional and Doppler color flow imaging. The patient diagnoses were transposition of the great arteries (n = 20), tetralogy of Fallot (n = 38), coarctation of the aorta (n = 24), complete atrioventricular (AV) canal (n = 15), atrial septal defect (n = 8), ventricular septal defects (n = 3), pulmonary stenosis (n = 4), aortic stenosis (n = 8) and subaortic stenosis (n = 9). In arterial tract stenosis, there was high correlation between Doppler estimates and catheterization-derived measurements of residual right ventricular outflow tract obstruction in patients after the arterial switch operation for transposition of the great arteries (r = 0.95) as well as in patients after corrective repair of tetralogy of Fallot (r = 0.84). In semilunar/AV valve regurgitation, graded as none, mild, moderate or severe, echocardiographic estimates correlated exactly with angiographic grading in 84% and differed by one angiographic grade in the other 16%. In residual left to right shunting, no hemodynamically significant shunt was missed by echocardiography. For residual shunts at the ventricular level (n = 32), addition of Doppler color flow imaging improved the sensitivity (from 63% to 94%) and the negative predictive value (from 88% to 98%). In elevated right ventricular pressure, Doppler-derived right ventricular-right atrial pressure estimates in 24 patients correlated well with catheterization measurements (r = 0.93). Combined two-dimensional and Doppler color flow echocardiography was highly accurate in the prospective evaluation of these four types of postoperative residual.

Cardiac Catheterization↗
PubMed1989

Hypoplastic left heart syndrome: lack of correlation between preoperative demographic and laboratory findings and survival following palliative surgery.

To determine whether preoperative demographic and metabolic variables correlated with early or late survival following palliative surgery for hypoplastic left heart syndrome, we reviewed the charts of 89 patients operated upon from October 1984 to January 1987. The variables analyzed were age at operation, lowest preoperative pH and H2CO3, highest preoperative arterial oxygen saturation, the occurrence of a preoperative cardiorespiratory arrest, and location of birth relative to the surgical institution. The data were evaluated by chi-squared, multivariate, and life-table analyses to the end of the first postoperative year. None of the factors analyzed significantly correlated with either short-term (less than or equal to 30 days) or long-term (greater than 30 days) survival. Thus, neither demographic nor metabolic factors including prior cardiorespiratory arrest should be considered contraindications to surgical palliation for hypoplastic left heart syndrome.

Age Factors↗
PubMed1989

Two-dimensional and Doppler echocardiographic assessment of neonatal arterial repair for transposition of the great arteries.

The arterial switch procedure has become an accepted reparative technique for transposition of the great arteries with or without ventricular septal defect. In this study the accuracy of prospective noninvasive imaging in detecting arterial tract obstruction and the prevalence and severity of arterial valvular regurgitation (as assessed by Doppler ultrasound) were evaluated in survivors of arterial repair. All 53 study patients underwent two-dimensional echocardiographic examination 2 days to 20 months (median 7 months) postoperatively; 43 patients also had pulsed and continuous wave Doppler studies. The accuracy of the noninvasive evaluation of arterial tract obstruction was determined by comparison of Doppler maximal instantaneous gradients with peak to peak gradients at nonsimultaneous catheterization in 26 patients. Twenty-one (81%) of the 26 patients underwent catheterization and successful pulsed and continuous wave Doppler examination of the right heart; 17 (81%) of these 21 had a maximal pressure gradient within 20 mm Hg of the peak to peak gradient obtained at catheterization. Echocardiographic identification of the stenotic site was correct in all eight of the patients in this group requiring reoperation. Twenty-three (88%) of the 26 patients who underwent catheterization had successful Doppler interrogation of the aortic tract; 22 (96%) of these 23 had a maximal instantaneous gradient within 20 mm Hg of the peak to peak catheterization gradient. Fourteen (32%) of 43 patients had mild or moderate pulmonary regurgitation by Doppler study. Three (7%) of the 43 had mild aortic regurgitation.

Aortic Valve Insufficiency↗