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Biomedical subjects

A J Chin

Publications and source records attributed to A J Chin.

At least 55 records · Page 3Linked to original sources
PubMed1989

Pulmonary artery configuration after palliative operations for hypoplastic left heart syndrome.

Pulmonary artery architecture and symmetry after palliative operations for hypoplastic left heart syndrome may affect subsequent suitability for a modified Fontan operation. Two-dimensional echocardiography was used to measure pulmonary artery diameter and assess symmetry after two types of systemic-pulmonary artery shunts: modified right Blalock-Taussig shunt (14 patients) and central shunt (from underside of aortic arch gusset to pulmonary artery confluence) (14 patients). Age, weight, preoperative diameter of right and left pulmonary arteries (proximal, middle, and distal segments), and mean interval between preoperative and postoperative echocardiographic studies (20.2 +/- 4.4 days in the Blalock shunt group; 19.1 +/- 6.8 days in the central shunt group) were similar. Early postoperatively, patients with a Blalock shunt showed a significant decrease in the diameter of all pulmonary artery segments except the distal right pulmonary artery. The diameters tapered from distal right to distal left pulmonary artery in this group. Patients with the central shunt had a significant decrease in the diameter of all pulmonary artery segments. There were no significant differences when cross comparisons were made of the various pulmonary arterial segments in patients after a central shunt. Similar findings persisted in 19 patients from both groups who had a late postoperative echocardiogram (mean interval between studies = 271 days in the group of 10 patients with Blalock shunt and 167 days in the group of nine patients with a central shunt). In conclusion, the central shunt preserves pulmonary artery symmetry, which may be important in candidates for the Fontan operation in infancy.

Echocardiography↗
PubMed1989

Pulmonary artery index. A nonpredictor of operative survival in patients undergoing modified Fontan repair.

The importance of pulmonary artery size and the value of a standardized pulmonary artery index (PAI) in predicting outcome after Fontan's repair have previously been reported and questioned. We retrospectively reviewed 29 patients undergoing modified Fontan repair at The Children's Hospital of Philadelphia to examine the relation between preoperative PAI (determined echocardiographically) and operative mortality. Twenty-four of these 29 patients underwent pulmonary artery augmentation at the time of Fontan repair. PAIs ranged from 48 to 541 mm2/m2. Operative mortality was 21%. PAI ranged from 68 to 233 mm2/m2 in nonsurvivors and from 48 to 541 mm2/m2 in survivors. There was no statistically significant difference in PAI between survivors and nonsurvivors; the lowest PAI associated with survival (48 mm2/m2) was one fourth of the lowest PAI value previously reported. There was a trend, not statistically significant, toward increased survival in those with larger PAIs. We conclude that patients should not be excluded from consideration for Fontan's repair solely on the basis of pulmonary artery size.

Child↗
PubMed1988

Fate of the pulmonic valve after proximal pulmonary artery-to-ascending aorta anastomosis for aortic outflow obstruction.

Transection of the main pulmonary artery and end-to-side anastomosis of the proximal pulmonary artery to the ascending aorta has been increasingly used in palliative surgery for cardiac malformations such as single ventricle with small outlet foramen (bulboventricular foramen) and hypoplastic left-heart syndrome. To evaluate pulmonary valve competence after this operation, we used color Doppler flow mapping to examine 45 survivors of pulmonary artery-to-ascending aorta anastomosis a median of 202 days postoperatively. Of 37 patients with hypoplastic left heart syndrome, mild regurgitation was detected in 9 (24%) and moderate regurgitation in 1 (3%). Of 8 with other lesions, mild regurgitation was observed in 2 and moderate regurgitation in 1. Seven of 11 patients imaged greater than or equal to 12 months postoperatively had regurgitation. In summary, one-fourth of survivors developed mild pulmonary regurgitation. Its presence should not be considered a contraindication to eventual application of Fontan's principle, although further follow-up appears warranted because the long-term fate of pulmonary valve function is not yet known.

Anastomosis, Surgical↗
PubMed1988

The significance of tricuspid regurgitation in hypoplastic left-heart syndrome.

Palliation of hypoplastic left-heart syndrome involves use of the morphologic right ventricle as the systemic ventricle and the tricuspid valve (in cases of mitral atresia/stenosis) or the common atrioventricular valve (in cases of malaligned atrioventricular canal) as the systemic atrioventricular valve. To determine the relationship between tricuspid or common atrioventricular valve function and the ultimate outcome of palliative surgery, 100 patients with hypoplastic left-heart syndrome were evaluated preoperatively by Doppler echocardiography to determine the degree of tricuspid regurgitation. These patients were then followed serially to assess changes with time in the functional status of the tricuspid or common atrioventricular valve and to determine the correlation of tricuspid or common atrioventricular valve regurgitation with survival. We discovered that tricuspid or common atrioventricular valve regurgitation is common in hypoplastic left-heart syndrome. Thirty-seven percent of the patients had mild, 13% had moderate, and 3% had severe tricuspid or common atrioventricular valve regurgitation on their preoperative Doppler echocardiograms. Throughout the first 2 postoperative years most patients had no significant change in the degree of tricuspid or common atrioventricular valve regurgitation when findings were compared to those of the preoperative echocardiogram. Patients with moderate or severe tricuspid or common atrioventricular valve regurgitation preoperatively had a significant reduction in their survival when contrasted with patients with no or mild atrioventricular valve regurgitation. We therefore conclude that tricuspid or common atrioventricular valve competence is a significant factor in long-term survival after palliative surgery for hypoplastic left-heart syndrome. This function, however, appears to be unaffected by palliation and remains relatively constant over the first 2 postoperative years.

Female↗
PubMed1988

Long-term neurostimulation of skeletal muscle: its potential for a tether-free biologic cardiac assist device.

Skeletal muscle has a tremendous capacity to adapt. This adaptive phenomenon is seen perhaps to the greatest extent when skeletal muscle is subjected to chronic low frequency stimulation via the motor nerve. There is a decrease in glycolytic enzymes and an increase in oxidative enzymes, as well as a change in the contractile proteins and an increase in the mitochondrial volume fraction of the muscle fiber. These adaptive changes result in a muscle that is considerably more fatigue-resistant. Specifically herein, we report on a pneumatic aortic counterpulsator device powered by skeletal muscle. These muscle pumps functioned continuously and pumped blood effectively in tether-free animals for several weeks.

Adaptation, Physiological↗
PubMed1988

Skeletal muscle grafts applied to the heart. A word of caution.

Latissimus dorsi pedicle grafts (LDPGs) were wrapped around the heart in eight dogs. In four dogs, the LDPGs were stimulated chronically; the remaining four dogs served as unstimulated controls. Right-sided cardiac filling pressures were normal in all dogs when measured 4 months after graft application. Mean tension generated by the viable LDPGs was 153 +/- 49.9 g. LDPGs contracting in synchrony with the heart did not increase cardiac output. In one dog, the aortic pressure changed from 140/100 to 155/85 mm Hg during synchronous contraction of the LDPG. Three dogs were placed on cardiopulmonary bypass, and their hearts were placed in fibrillation. The LDPGs were then stimulated at a burst frequency of 85 Hz and contracted vigorously. Under these conditions, the left ventricular pressure increased by an average of 15 mm Hg with each LDPG contraction; however, the mean aortic pressure was virtually unchanged. Left ventricular and aortic pressures of 125/20 and 125/65 mm Hg, respectively, could be obtained with manual compression of the fibrillating heart. This study indicates that although LDPGs can be made to contract chronically and in synchrony with the heart, they do not necessarily augment left ventricular performance.

Animals↗
PubMed1987

The pattern of cardiovascular malformation in the CHARGE association.

Congenital heart disease occurred in 64% of patients with the CHARGE (coloboma, heart disease, choanal atresia, retardation of postnatal growth and mental development, genitalia hypoplasia, and ear anomalies) association (55% of 67 previously described patients and 100% of 16 new patients). Of those with congenital heart disease, 42% had conotruncal anomalies (tetralogy of Fallot, double-outlet right ventricle, truncus arteriosus), and 36% had aortic arch anomalies (vascular ring, aberrant subclavian artery, interrupted aortic arch). This striking pattern of cardiovascular malformations is similar to that found in the DiGeorge sequence.

Abnormalities, Multiple↗
PubMed1987

Accuracy of subcostal two-dimensional echocardiography in prospective diagnosis of total anomalous pulmonary venous connection.

Since reparative surgery without cardiac catheterization has been advocated for certain lesions such as total anomalous pulmonary venous connection (TAPVC), it is important to assess the accuracy of two-dimensional (2-D) echocardiography in the prospective diagnosis of this lesion. Abandoning traditional cardiac catheterization and angiography would be justified only if all surgically relevant anatomic features could be consistently displayed noninvasively. Consequently, we reviewed our experience with TAPVC to determine the suitability of subcostal 2-D echocardiography as the sole prospective diagnostic tool. Over a 5-year period, of 2444 infants under 2 years of age who underwent subcostal 2-D echocardiography, 38 were diagnosed as having TAPVC as the only major cardiac defect. There were no false-negative or false-positive cases during the time of the study. Drainage sites were diagnosed correctly in 36 (95%). Of the five cases of mixed-type TAPVC, the second drainage site was missed by 2-D echocardiography in two cases.

Echocardiography↗
PubMed1987

Transposition of the great arteries with aortic arch obstruction. Anatomical review and report of surgical management.

Transposition of the great arteries (S,D,D) is a common congenital cardiovascular malformation that is occasionally associated with ventricular septal defect and left ventricular outflow tract obstruction. Recently right ventricular outflow tract obstruction associated with an aortic arch anomaly has been recognized as an infrequent but important variant of transposition of the great arteries, and this constellation presents a unique surgical challenge. Five infants with this constellation whose systemic circulation was dependent on flow through the ductus arteriosus have undergone definitive surgical treatment with four survivors. An anatomical review of 129 specimens with transposition of the great arteries revealed that 17% had right ventricular outflow tract obstruction and 7% had associated aortic arch obstruction as well. All specimens with aortic arch obstruction and ventricular septal defect except one had a malalignment type ventricular septal defect. Although several treatment options may be considered, recent experience with arterial switch repair in the neonate with transposition of the great arteries (S,D,D) prompted repair in these patients by arterial switch, ventricular septal defect closure, repair of aortic arch obstruction, and augmentation of the right ventricular outflow tract.

Aorta, Thoracic↗
PubMed1987

Skeletal muscle ventricles in circulation. One to eleven weeks' experience.

Skeletal muscle ventricles were constructed from canine latissimus dorsi and connected to the thoracic aorta in six dogs. These ventricles were stimulated to contract synchronously during diastole. The skeletal muscle ventricles were capable of continuous stroke work when placed within the arterial circulation for several weeks. Effective synchronous diastolic counterpulsation was produced. These results demonstrate that diastolic counterpulsators can be constructed from skeletal muscle and in the future may provide a feasible therapeutic alternative for the treatment of end-stage cardiac failure.

Animals↗
PubMed1986

Postmortem echocardiography and tomographic anatomy of hypoplastic left heart syndrome after palliative surgery.

A study was undertaken to improve the understanding of the 3-dimensional (3-D) topology of a complex surgical reconstruction. The pathologic anatomy was investigated by first fixing postmortem heart specimens in such a way as to preserve the 3-D relations. Next, a technique for postmortem 2-D echocardiography was developed to aid in selection of tomographic planes for sectioning the specimens. Subsequent adjustment of planes of section was made to better show particular facets of the anatomy. The material for this investigation was drawn from cases of hypoplastic left heart syndrome after surgical palliation by the Norwood procedure. Three potential hemodynamic sequelae--restrictive inter atrial communication, aortic obstruction at any level and distortion of the pulmonary artery confluence--served as the anatomic focus for this study. Careful preservation of 3-D topology and postmortem 2-D echocardiographic imaging coupled with tomographic sectioning of specimens led to development of new, clinically relevant echocardiographic views for imaging specific atrial septal and aortic arch anomalies. These techniques offer insight into the spectrum of anatomic sequelae of this type of surgery and may be applied to echocardiographic imaging of patients and refinement of surgical technique for other forms of complex congenital heart disease.

Aorta, Thoracic↗
PubMed1986

Subaortic obstruction in complex congenital heart disease: management by proximal pulmonary artery to ascending aorta end to side anastomosis.

Six patients with univentricular heart and one patient with d-transposition of the great arteries had transection of the main pulmonary artery with an end to side anastomosis of the main pulmonary artery to the ascending aorta to relieve subaortic obstruction. Two operations were performed as a palliative procedure within the first 6 months of life and five were performed as part of a definitive repair (four modified Fontan procedures and one repair of transposition of the great arteries with ventricular septal defect). There was one surgical death (14%) occurring 1 day postoperatively from low cardiac output. The remaining six patients are doing well 1 to 19 months postoperatively (mean 11.4 months). The proximal pulmonary artery to ascending aorta end to side anastomosis is an effective means of bypassing subaortic obstruction associated with complex congenital heart disease.

Aorta↗
PubMed1986

Two-dimensional echocardiographic diagnosis of pulmonary artery sling in infancy.

The vascular anomaly in which the left pulmonary artery arises from the right pulmonary artery and passes posteriorly and leftward between the trachea and the esophagus is termed a pulmonary artery sling. Two-dimensional echocardiograms were performed in five infants with this anomaly and successfully identified it in four, including one patient with truncus arteriosus communis. The subxiphoid long-axis sweep was useful in identifying the origin and initial course of the left pulmonary artery, and short-axis subxiphoid views showed both its origin from the right pulmonary artery and its initial posterior course. Angulation toward the cardiac apex displayed the right pulmonary artery in cross section anteriorly and the left pulmonary artery in cross section posteriorly. A transducer orientation midway between the subxiphoid long- and short-axis positions was helpful in distinguishing a large right upper lobe branch of the right pulmonary artery from a pulmonary artery sling. The precordial short-axis plane displayed the origin and initial posterior and leftward course of the left pulmonary artery, while the bifurcation of the main pulmonary artery, usually easily seen in this view, could not be demonstrated. Two-dimensional echocardiography offers a rapid, noninvasive diagnosis of pulmonary artery sling in infants.

Aorta↗
PubMed1986

Congenital heart disease in supernumerary der(22),t(11;22) syndrome.

Congenital heart disease occurred in 62% of the reported cases of supernumerary der(22) syndrome. These were most commonly acyanotic lesions such as atrial septal defect, ventricular septal defect or patent ductus arteriosus. Heart disease did not, however, appear to be a major determinant of survival.

Child↗
PubMed1986

Analysis of potential anatomic or physiologic determinants of outcome of palliative surgery for hypoplastic left heart syndrome.

Sixty-five consecutive patients with hypoplastic left heart syndrome underwent preoperative two-dimensional echocardiographic examination (and Doppler examinations in 33) to assess parameters potentially predictive of early (less than or equal to 30 days) mortality after palliative surgery. The six anatomic and physiologic factors considered were right ventricular wall thickness, right ventricular shortening, tricuspid (or common atrioventricular valve) regurgitation, ascending aortic size, distal aortic arch anatomy, and atrial septal anatomy. Right ventricular wall thickness was 3 or 4 mm in 59 of 65 patients and did not correlate with outcome. There was no significant difference in early mortality between patients with abnormal right ventricular shortening (11 of 23 patients [48%]) and those with normal right ventricular shortening (19 of 42 patients [45%]). Tricuspid or common atrioventricular valve regurgitation was found in 15 of 33 patients and eight of these suffered early death (53%) compared with six (33%) among the 18 patients without atrioventricular valve regurgitation. Ascending aortic diameter ranged from 2 to 6 mm and did not correlate with early outcome. Coarctation of the aorta, found in 18 of 54 patients (33%), and leftward displacement of the superior attachment of septum primum, noted in 33 of 63 patients (52%), likewise did not correlate with outcome. Therefore, at present, variations in the six parameters analyzed cannot be considered contraindications to palliative surgery in patients with hypoplastic left heart syndrome.

Echocardiography↗