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Biomedical subjects

I S Chiu

Publications and source records attributed to I S Chiu.

At least 73 records · Page 4Linked to original sources
PubMed1992

Fate of the autologous tri-cusp-valved pericardial conduit in the right ventricular outflow tract of growing pigs.

No perfect valve or valved conduit is currently available to reconstruct the right ventricular outflow tract (RVOT) in pediatric patients. To investigate the fate of autologous pericardial valved conduit, twenty piglets weighing 12.2 +/- 1.4 kg were divided into two groups. In 10 of them, the pericardium was immersed in 0.6% glutaraldehyde for 5 minutes (Gr PG) and then washed with normal saline. In the other 10 pigs, the pericardium was immersed in normal saline only (Gr PN) after procurement. Afterwards the autologous pericardium was tailored as designed to build a tri-cusp-valve inside the pericardial conduit with reconstruction of the sinus of Valsalva. This conduit was connected to the pulmonary trunk (PT) distally and RVOT proximally without a pump. The PT was then doubly ligated just above the annulus. The pigs survived 114 +/- 92 days in Gr PG and 82 +/- 50 days in Gr PN. The body weight increased to 42 +/- 29 kg in Gr PG and 30 +/- 9 kg in Gr PN. No cusps adhered to the conduit wall in either group. In Gr PN, the valve became retracted; in 7 of them an aneurysm developed proximal to the stenotic pulmonary valve, while only one pig in Gr PG developed an aneurysm. In Gr PG, the leaflet and conduit showed evidence of growth. In contrast, no evidence of valve growth was found in Gr PN. Calcification was evident more in Gr PG than in Gr PN either on the leaflet (9/10 vs. 5/10) or in the wall of conduit (8/10 vs. 6/10), but the differences were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Effects of atrial natriuretic factor in chronic hypoxic spontaneously hypertensive rats.

The present study was designed first to investigate the pulmonary hypertensive effects of chronic hypoxia in spontaneously hypertensive rats and second to compare the cardiovascular effects of atrial natriuretic factor on rats exposed to hypoxia and on control rats kept at sea level. Catheters were placed in the femoral and pulmonary arteries for measurement of mean systemic arterial pressure and mean pulmonary arterial pressure. The cardiac output was measured by thermodilution method. It was found that 4 weeks of simulated 18,000-foot hypoxia led to polycythemia, right ventricular hypertrophy, and pulmonary hypertension, which resulted from an increased pulmonary vascular resistance. However, systemic arterial pressure was not significantly different between the two groups of rats. Atrial natriuretic factor administration decreased systemic arterial pressure and pulmonary arterial pressure to a lesser extent in the hypoxic group compared with the sea level control group. It is concluded that these animals showed an impaired response to atrial natriuretic factor after long-term exposure to hypoxia.

Animals↗
PubMed1991

Left atrial isomerism in the adolescence: report of two cases.

Atrial isomerism is very rare in adolescence. Two cases of left atrial isomerism are reported here in 2 females, aged 21 and 19 years. They had presented with cyanosis and dyspnea since childhood. High kilovoltage filter films showed a bilateral morphologically left bronchus. Cardiac catheterization in Case 1 revealed normal pulmonary artery pressure, severe subvalvular pulmonic stenosis, a double outlet right ventricle, a significant oxygen step-up at the atrial level and moderate systemic oxygen desaturation; while Case 2 disclosed pulmonary hypertension and mild systemic oxygen desaturation. Both cases had the following anatomical features: ipsilateral connection of pulmonary veins to the bilateral morphological left atrium; interrupted inferior vena cave with azygos or hemiazygos continuation; total anomalous hepatic venous return to the right-sided atrium; complete atrioventricular canal. The diagnoses were confirmed in both cases at surgical correction.

Adult↗
PubMed1991

Surgical treatment of tricuspid atresia.

From April 1984 to July 1989, 6 consecutive patients underwent an orthoterminal repair for classical tricuspid atresia (TA). Their ages ranged from 6 to 14 years with a mean of 8.3 years. Four patients had ventriculoarterial concordance (VA-con) and 2 had ventriculoarterial discordance (VA-dis). One patient with VA-dis underwent a total cavopulmonary connection. The other five patients had modified Fontan operation. All 6 patients survived the operation. At a mean follow-up of 28 months, all patients were in the New York Heart Association Functional Class I. A follow-up color Doppler echocardiogram showed that the forward pulmonary flow was mainly during the ventricular diastolic phase except in one case. In this case, a tripartite right ventricle (RV) could be identified by angiocardiogram 4.5 years after the atrioventricular (A-V) connection without obliteration of the trabecular portion. A big "V" wave was demonstrated in the RV and pulmonary trunk. The pulmonary valve was closed in the ventricular diastolic phase. In the other case with an A-V connection and obliteration of the trabecular portion, revealed a fixed-open pulmonary valve with a forward flow more in the atrial systolic phase than in the ventricular systolic phase. The graded exercise test in these 2 patients with an A-V connection revealed a normal functional capacity. The mean maximal oxygen uptake was 8.4 +/- 0.1 METS. In the other 3 children without an A-V connection the mean maximal oxygen uptake was 6.6 +/- 0.5 METS. We concluded that the Fontan-like repair was the procedure of choice for TA, and that excellent surgical results could be obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

The atrioventricular conduction axis of hearts with isolated ventricular septal defects.

We studied the surgical anatomy of 14 hearts with isolated ventricular septal defects and the precise relationship of the atrioventricular conduction axis to their rims. Ten of these hearts were investigated by serial sectioning of their atrioventricular conduction systems. All defects were divided into perimembranous or muscular types as previously suggested by Soto et al. The distinguishing feature of the perimembranous defect was that the central fibrous body formed part of its rim, this fact indicated that the conduction tissue was always to the right of the surgeon's hand when the defect was approached through the right atrium. The precise relationship of the ventricular conduction tissues varied depending upon whether the perimembranous defect extended into the inlet, trabecular or outlet components of the muscular septum. The nonbranching bundle was closest to the septal rim in the inlet and trabecular defects, frequently being buried in a remnant of the interventricular membranous septum. However, in these defects the nonbranching and branching bundles were also found in other specimens remote from the septal crest, yet were carried on the left ventricular aspect of the septum. In perimembranous inlet defects, the penetrating bundle detoured deep into the central fibrous body. In perimembranous outlet defects, the conduction tissues were remote from the septal crest. In contrast to these findings, the conduction tissues were away from the edges of the defects in trabecular and outlet muscular defects. In conclusion, in the perimembranous inlet defect, the placement of the sutures on the annulus of tricuspid valve should be avoided in view of its abnormal long penetrating bundle.

Atrioventricular Node↗
PubMed1989

Is the sinus node visible grossly? A histological study of normal hearts.

The sinus node is said to be occasionally visible in the human heart, while some have denied this visibility. This histological study of the normal sinus node was made on 11 adults and 10 infants. The node was always located subepicardially along the terminal groove at the junction of the superior caval vein and the right atrium. When no fatty infiltration (all infants and 2 adults) or minimal fatty tissue (2 adults) was found over the epicardial side of the node, it was not visible grossly. When fatty infiltration was obvious, then the node could be identified grossly as a yellowish spindle-shaped structure along the terminal groove. This arrangement was observed in 7 adults. The majority of nodes were in lateral position, but the so-called horseshoe arrangement was seen in 2 infants and 2 adults. The artery to the sinus artery was located centrally or eccentrically in the majority of cases, but the artery ramified through the nodal substance in 1 infant and 4 adults. We conclude that the node is not visible grossly in either the infant hearts or in those adult hearts without fatty infiltration. The whole cephalic part of the terminal groove should be carefully avoided to be sure of preventing the injury to the node during cardiac surgery.

Adult↗
PubMed1989

Reconstruction of right ventricular outflow tract by autologous pericardial tri-semilunar valve with sinus of Valsalva: report of a case with absent pulmonary valve.

The choice of a valved conduit or a valve in the right ventricular outflow tract remains a problem. We propose to reconstruct the pulmonary valve inside the patient's own pulmonary trunk by autologous pericardium in tri-semilunar fashion with concomitant formation of the sinus of Valsalva and commissure. This operation was carried out on a 7-year-old girl suffering from Fallot's tetralogy with an absent pulmonary valve. The ventricular septal defect was repaired and the pulmonary valve reconstructed as above. The postoperative cross-sectional echocardiogram, color Doppler echocardiogram and angiogram showed a pliable tri-semilunar valve across the pulmonary outflow tract without regurgitation. It is concluded that firstly, the sinus of Valsalva is indispensable for a stentless semilunar valve to be competent; secondly, reconstruction of the semilunar valve inside the pulmonary trunk by autologous pericardium is recommended for the absent pulmonary valve syndrome, but the long-term fate of this pericardial valve awaits further evaluation.

Child↗
PubMed1988

Clinical implications of atrial isomerism.

Right atrial isomerism or left atrial isomerism is frequently diagnosed as situs ambiguous without further discrimination of the specific morbid anatomy. Thirty six cases of right atrial isomerism and seven cases of left atrial isomerism were collected from the records and pathological museum at the National Taiwan University Hospital. There was a necropsy report for 18 cases. In all patients one or more of the following conditions was met: (a) isomeric bronchial anatomy, (b) echocardiographic and angiocardiographic evidence of isomerism, and (c) surgical or necropsy evidence of abnormal atrial anatomy. An anomalous pulmonary venous connection was present in 55% of patients with right atrial isomerism; in left atrial isomerism one case (14%) had a partial anomalous pulmonary venous connection. Forty per cent of cases of anomalous pulmonary venous connection with right atrial isomerism had obstruction. Six (86%) of seven cases with left atrial isomerism had an ambiguous biventricular atrioventricular connection. In contrast, univentricular atrioventricular connection (26 of 36, 72%) was significantly more common in right atrial isomerism. A common atrioventricular valve was the most frequent mode of connection in both forms. Two discrete atrioventricular valves were significantly more common in left atrial isomerism. Atrioventricular valve regurgitation was detected in 14 cases. Double outlet right ventricle was the most common type of ventriculoarterial connection. The most commonly cited causes of death after either palliative or definitive operation were undetected anomalous pulmonary venous connection, pulmonary venous stricture, and uncorrected atrioventricular valve or aortic regurgitation complicated by abnormal coagulation. Although the prognosis is poor, successful operation depends on knowledge of the precise anatomical arrangement associated with atrial isomerism.

Abnormalities, Multiple↗
PubMed1988

Growth of the aortic anastomosis in pigs. Comparison of continuous absorbable suture with nonabsorbable suture.

Growth at the anastomotic site after continuous vascular anastomosis in the pediatric patient remains a problem. Primary end-to-end anastomosis of the infrarenal aorta was performed with absorbable Maxon suture or nonabsorbable Prolene suture in 20 piglets. Ten of the Maxon suture group and nine of the Prolene suture group survived; one pig died of infection. The animals were put to death 6 months after the operation. Each abdominal aorta was removed and a roentgenogram was obtained. The aorta was then burst-tested to 300 mm Hg, measured, and examined both grossly and histologically. All anastomoses were patent and no burst failures were observed in either group. However, Prolene sutures protruded into lumen and were partially embedded in the aortic wall in all animals in the Prolene suture group. Thrombus adhered to the intraluminal Prolene suture in six of nine animals. The growth of the anastomotic area was wider in the Maxon suture group (446.4% +/- 131.8% versus 317.6% +/- 121.5%, p less than 0.05). Stenosis was more common in the Prolene suture group (7/9) than in the Maxon suture group (1/10) (p less than 0.01), but the distal segment was widely patent in both groups. Dilatation at the anastomotic site was present in eight of 10 pigs in the Maxon suture group and in two of nine in the Prolene suture group. Histologic study showed that the area of tissue reaction was more prominent in the Prolene suture group. No sutures were observed in the Maxon suture group. We therefore recommend the use of absorbable Maxon sutures for anastomoses in which the suture line must be able to grow.

Absorption↗
PubMed1985

The landmarks to the atrioventricular conduction system in hearts with absence or unroofing of the coronary sinus.

Histologic studies were made of the conduction system of two hearts, one with absence and the other unroofing of the coronary sinus. The findings show that, when present, the triangle of Koch and the orifice of the coronary sinus are usually good guides to the atrioventricular conduction axis. However, when these landmarks are malformed, or there is malalignment of the atrial and ventricular septal structures, a better guide is the fusion point of the ventricular septum with the atrioventricular junction.

Autopsy↗
PubMed1984

Morphologic features of an intact ventricular septum susceptible to subpulmonary obstruction in complete transposition.

Twenty-five autopsy specimens of complete transposition of the great arteries with intact ventricular septum (VS) were categorized as "bulging" (11 cases) or " nonbulging " (14 cases) according to the curvature of the VS. A fibrous ridge was observed on the VS, especially at the site of mitral apposition in 82% of the bulging group. No fibrous ridge was seen in the nonbulging group. An objective index of anteroposteriorness was then designed to measure the distance between the midpoint of the nonfacing aortic cusp line and the left anterior descending coronary artery. In the bulging group, the aorta lay more anterior to the pulmonary trunk, whereas in the hearts with a straight VS, the aorta tended to lie side by side and to the right of the pulmonary trunk. The midmitral line is an imaginary line in the middle of the anterior mitral leaflet. The more the pulmonary valve is wedged toward the right atrioventricular junction, the more the midmitral line will pass through the nonfacing pulmonary cusp rather than right pulmonary cusp or the nonfacing /right commissure. This was so in 100% of the bulging group, but in only 36% of the nonbulging group. These differences between the groups in terms of anteroposterior index and extent of wedging were statistically significant. In conclusion, if the aorta lies more anterior and to the left of pulmonary trunk rather than side by side and to the right, the "wedged" subpulmonary area will be more susceptible to obstruction caused by septal bulging. Cross-sectional echocardiography is the best means of diagnosing these features.

Adolescent↗
PubMed1984

Sternal splintage with rib graft to avoid retrosternal compression after open heart surgery--an experimental study.

We present an experimental study in monkeys of sternal splintage using single or multiple rib grafts. This technique provides an enlarged retrosternal space, at the same time giving good stability of the mediastinum. In this way it is possible to avoid compression of the dilated heart, an external conduit or an assist device as may happen on occasion after conventional sternal closure.

Animals↗