Myocardial wall stiffening in a mouse model of persistent truncus arteriosus

Background

Genetic and epigenetic programs regulate dramatic structural changes during cardiac morphogenesis. Concurrent biomechanical forces within the heart created by blood flow and pressure in turn drive downstream cellular, molecular and genetic responses. Thus, a genetic-morphogenetic-biomechanical feedback loop is continually operating to regulate heart development. During the evolution of a congenital heart defect, concomitant abnormalities in blood flow, hemodynamics, and patterns of mechanical loading would be predicted to change the output of this feedback loop, impacting not only the ultimate morphology of the defect, but potentially altering tissue-level biomechanical properties of structures that appear structurally normal.

Aim

The goal of this study was to determine if abnormal hemodynamics present during outflow tract formation and remodeling in a genetically engineered mouse model of persistent truncus arteriosus (PTA) causes tissue-level biomechanical abnormalities.

Methods

The passive stiffness of surface locations on the left ventricle (LV), right ventricle (RV), and outflow tract (OFT) was measured with a pipette aspiration technique in Fgf8;Isl1Cre conditional mutant embryonic mouse hearts and controls. Control and mutant experimental results were compared by a strain energy metric based on the measured relationship between pressure and aspirated height, and also used as target behavior for finite element models of the ventricles. Model geometry was determined from 3D reconstructions of whole-mount, confocal-imaged hearts. The stress-strain relationship of the model was adjusted to achieve an optimal match between model and experimental behavior.

Results and conclusion

Although the OFT is the most severely affected structure in Fgf8;Isl1Cre hearts, its passive stiffness was the same as in control hearts. In contrast, both the LV and RV showed markedly increased passive stiffness, doubling in LVs and quadrupling in RVs of mutant hearts. These differences are not attributable to differences in ventricular volume, wall thickness, or trabecular density. Excellent agreement was obtained between the model and experimental results. Overall our findings show that hearts developing PTA have early changes in ventricular tissue biomechanics relevant to cardiac function and ongoing development.

Long-term follow-up of persistent truncus arteriosus: Kuwait experience

OBJECTIVE

To evaluate the long-term results of patients in Kuwait who were operated for persistent truncus arteriosus (PTA).

SUBJECTS AND METHODS

The following data were collected for retrospective analysis from 24 medical records of consecutive patients with PTA in Kuwait between August 1993 and August 2009: demographics, morphology, management and outcome. Major associated abnormalities included interrupted aortic arch in 1 patient and abnormal coronary artery anatomy in 2.

RESULTS

Of the 24 patients, 16 underwent total intracardiac repair. The age at operation ranged from 15 days to 5 years (mean 166.19 ± 438.63 days) and weight ranged from 2.5 to 15 kg (mean 4.3 ± 3.01 kg). The right ventricle to pulmonary artery continuity was established with aortic homograft in 11, pulmonary homograft in 4 and by implantation of a Contegra conduit in 1 patient. Four patients had moderate truncal valve regurgitation requiring concomitant truncal valve repair. After a mean follow-up period of 81.81 ± 61.58 months (range 3-166) there was no death. Eight of the 16 (50%) patients underwent redo homograft operations. One patient who had concomitant truncal valve repair subsequently underwent aortic valve replacement.

CONCLUSION

The data showed that complete repair of PTA in the neonatal and early infancy period was the treatment with the best potential for survival. The homograft remained one of the conduits of choice to establish continuity between the right ventricle and the pulmonary artery in spite of the high incidence of conduit redo operations.

Coronary artery embryogenesis in cardiac defects induced by retinoic acid in mice

BACKGROUND

Although normal coronary artery embryogenesis is well described in the literature, little is known about the development of coronary vessels in abnormal hearts.

METHODS

We used an animal model of retinoic acid (RA)-evoked outflow tract malformations (e.g., double outlet right ventricle [DORV], transposition of the great arteries [TGA], and common truncus arteriosus [CTA]) to study the embryogenesis of coronary arteries using endothelial cell markers (anti-PECAM-1 antibodies and Griffonia simplicifolia I (GSI) lectin). These markers were applied to serial sections of staged mouse hearts to demonstrate the location of coronary artery primordia.

RESULTS

In malformations with a dextropositioned aorta, the shape of the peritruncal plexus, from which the coronary arteries develop, differed from that of control hearts. This difference in the shape of the early capillary plexus in the control and RA-treated hearts depends on the position of the aorta relative to the pulmonary trunk. In both normal and RA-treated hearts, there are several capillary penetrations to each aortic sinus facing the pulmonary trunk, but eventually only 1 coronary artery establishes patency with 1 aortic sinus.

CONCLUSIONS

The abnormal location of the vessel primordia induces defective courses of coronary arteries; creates fistulas, a single coronary artery, and dilated vessel lumens; and leaves certain areas of the heart devoid of coronary artery branches. RA-evoked heart malformations may be a useful model for elucidating abnormal patterns of coronary artery development and may shed some light on the angiogenesis of coronary artery formation.

Prenatal diagnosis of an unexpected interstitial 22q11.2 deletion causing truncus arteriosus and thymic hypoplasia in a ring 22 chromosome derived from a maternally inherited paracentric inversion

OBJECTIVE

To present the prenatal diagnosis of an interstitial 22q11.2 deletion involving a ring 22 chromosome associated with truncus arteriosus and a hypoplastic thymus.

CASE

Following the sonographic diagnosis of a cystic hygroma at 12 weeks of gestation, chromosome analysis revealed a ring 22 chromosome.

RESULTS

Ring chromosomes typically result in the deletion of genetic material from the distal long and short arms of the affected chromosome. The presence of an interstitial deletion in a ring chromosome is therefore unusual. FISH analysis revealed an unexpected deletion involving the TUPLE1 gene in the DiGeorge/Velocardiofacial syndrome region in 22q11.2. Maternal chromosome analysis revealed the cause of the apparent interstitial deletion, a paracentric inversion in the long arm of chromosome 22, resulting in the distal long arm of 22q being located adjacent to the centromere and the proximal end being located near the telomere. The fetus was subsequently diagnosed with truncus arteriosus and a hypoplastic thymus, consistent with DiGeorge syndrome.

CONCLUSION

The ring chromosome 22 found in the fetus appears to have been derived from a rearrangement of the mother's inverted 22, resulting in ring formation and loss of the end of the distal long arm of the inverted 22, including the TUPLE1 locus, causing DiGeorge syndrome in the fetus. The apparent interstitial deletion was actually a terminal deletion in a maternally inherited rearranged chromosome 22.

Truncus arteriosus communis in a midtrimester fetus: comparison of prenatal ultrasound and MRI with postmortem MRI and autopsy

Different techniques are used in fetal cardiology, and their accuracy has been demonstrated on several occasions. Color Doppler US has proved to be a reliable and valuable tool in the diagnosis of fetal cardiac abnormalities. Magnetic resonance imaging (MRI) of the fetal heart has, so far, played no role in prenatal diagnostics. We report on a truncus arteriosus communis diagnosed prenatally during a screening ultrasound at 22 weeks of gestation. In addition to real-time ultrasound and color Doppler echocardiography, fetal MRI was performed. Fetal echocardiography arose suspicion of a type I common trunk. Fetal MR showed solely a widened vessel coursing retrocardially and additionally an inhomogeneous fluid distribution of the lung not shown on prenatal US. After termination of pregnancy at 23 weeks of gestation, MR fetography and autopsy were performed, and both found a type II common trunk. MR autopsy of the heart was very reliable in this case and could be an alternative when fetal pathology is not available for different reasons. Postmortem MRI was also able to demonstrate the inhomogeneous fluid distribution in the lung, which was confirmed by autopsy. Fetal and postmortem MR was reliable in the detection of an inhomogeneous fluid distribution in the lung not shown on prenatal US, providing a relevant additional finding to US. Therefore, MRI should be used more often in fetal cardiology, although it still must be further developed.

DiGeorge syndrome with truncus arteriosus: report of one case

DiGeorge syndrome is a rare disorder characterized by a spectrum of thymic and parathyroid gland abnormalities, conotruncal cardiac defects, and typical facial dysmorphism. We report a male infant with partial DiGeorge syndrome characterized by truncus arteriosus, typical facial dysmorphism, hypocalcemia, lymphocytopenia with T-cell deficiency, and chromosome 22q11.2 deletion. Transient lymphocytopenia was noted for 5 days after birth and hypocalcemia was corrected with calcium gluconate administration. Surgical correction of the truncus arteriosus was performed at the age of 3 months. Unfortunately, the patient subsequently had an unwitnessed cardiac arrest, and despite resuscitation, died at the age of 4 months.

Persistent truncus arteriosus in a rhesus monkey (Macaca mulatta)

A 47-day-old female rhesus macaque (Macaca mulatta) was examined because of a severe holosystolic heart murmur (grade 5/6) and signs of congestive heart failure. Results of physical examination, thoracic radiography, and cardiac ultrasonography confirmed an advanced stage of congestive heart failure. Due to the animal's age and clinical signs of disease, a congenital heart defect was suspected. Necropsy revealed a rare congenital heart defect known as persistent (common) truncus arteriosus.

Single origin of right and left pulmonary artery branches from ascending aorta with nonbranching main pulmonary artery: relevance to a new understanding of truncus arteriosus

We report the third known case of origin of the right and left pulmonary artery branches from the ascending aorta via a short common pulmonary artery. A large unbranching main pulmonary artery opened through a patent ductus arteriosus into the descending thoracic aorta. Preductal coarctation of the aorta and multiple congenital anomalies were also present. This rare cardiovascular malformation facilitates a new anatomic and developmental understanding of truncus arteriosus.

Persistent truncus arteriosus: pathologic anatomy in 54 cases

Fifty-four specimens of heart with persistent truncus arteriosus (PTA) were reviewed anatomically. According to the Collett-Edwards classification there were 28 examples of type I and 26 type II. The sex distribution was equal. The number of the truncal cusps ranged from one to four (42% tricuspid, 30% bicuspid, 24% quadricuspid, and 4% unicommissural). A unicommissural truncal valve has not been previously reported. In 72% of cases, the truncal valve leaflets were thickened or dysplastic. Two valves were stenotic. The truncus arteriosus originated from both ventricles equally in 42% of the cases, predominantly from the right ventricle in 42%, and predominantly from the left ventricle in 16% of the cases. In unoperated cases of PTA originating predominantly from the right ventricle, it appeared to us that usual operative correction might result in left ventricular outflow obstruction. Variations in coronary arterial origins and patterns were present in nearly half of the cases. A single coronary artery was observed in ten cases (18.5%). Stenosis of the ostium of one coronary artery was seen in each of four cases (7%). High posterior origin of the left coronary artery was observed in ten cases (18.5%). Among the associated cardiovascular anomalies, the most common were right aortic arch (36%) and interruption of the aortic arch (11%). Three cases with the latter condition exhibited crossed pulmonary arteries. Isolated cases with tricuspid atresia, vascular sling (left pulmonary artery arising from right pulmonary artery), and persistent common atrioventricular canal were encountered.

A cross between truncus arteriosus communis and aortopulmonary septal defect: a hitherto undescribed entity

Case history and necropsy findings of a 5-month-old infant with a unique heart defect with features of truncus arteriosus communis and aortopulmonary defect in combination with severe tricuspid stenosis are presented. There is a wide spectrum of remarkable heart defects between truncus arteriosus communis and aortopulmonary septal defect.

Factors associated with outcomes of persistent truncus arteriosus

OBJECTIVES

The purpose of this study was to identify trends and factors associated with outcomes of persistent truncus arteriosus (PTA).

BACKGROUND

Although there have been significant improvements, PTA continues to be associated with significant morbidity and mortality.

METHODS

We undertook a review of all consecutive cases of PTA (n = 205) presenting at our institution from 1953 to 1997. Data were collected regarding demographics, anatomy, management (surgical palliation and repair) and outcomes (mortality and reoperation).

RESULTS

Significant trends (p < or = 0.001) related to groups defined by year of birth were as follows: number of cases (1953-1967, n = 13; 1968-1977, n = 42; 1978-1987, n = 69; 1988-1997, n = 81), median age at first assessment (8 months, 42 days, 7 days and 2 days, respectively), proportion who did not have any surgery (58%, 27%, 22% and 11%), proportion who had an initial palliative procedure (25%, 37%, 6% and 2%), proportion who underwent PTA repair (31%, 59%, 72% and 88%), median age at PTA repair (11.2 years, 1.1 years, 1.6 months and 12 days) and proportion dying before hospital discharge after repair (50%, 63%, 56% and 41%). Since 1995, mortality before hospital discharge after repair has further decreased to 2/11 (18%). Increasing time to initial conduit replacement in hospital survivors was significantly related to larger sized conduit at repair (p = 0.02) and use of pulmonary homografts (vs. aortic homografts or xenografts; p = 0.002). Interventional catheterization to address conduit obstructions significantly increased conduit longevity.

CONCLUSIONS

Significant improvements in PTA outcomes are evident with trends toward earlier age at assessment and complete repair.

Truncus arteriosus with anomalous pulmonary venous connection

The anatomic, diagnostic, and management findings of 6 patients with truncus arteriosus and anomalous pulmonary venous connections are described. Additional risk factors indicative of poor prognosis were found in 3 of 4 patients with truncus arteriosus and totally anomalous pulmonary venous connection and in 1 patient with partially anomalous pulmonary venous connection.

Persistent truncus arteriosus in monozygotic twins: case report and literature review

We report on a pair of monozygotic twins with persistent truncus arteriosus. They had no evident clinical signs of DiGeorge syndrome. Pathologic examination of the placenta and DNA analysis in chromosomes 7, 8, and 15 was consistent with monozygosity. Fluorescence in situ hybridization test was negative for chromosome 22q11 microdeletion. Family history revealed a female cousin with tetralogy of Fallot. The isolated presence of this conotruncal abnormality in monozygotic twins is extremely rare. The genetic considerations are discussed.

A genetic assessment of trisomy 21 in a patient with persistent truncus arteriosus who died 38 years ago

A newborn baby with the unique combination of Down syndrome and persistent truncus arteriosus with interrupted aortic arch is described. The diagnosis of trisomy 21 was assessed 38 years after the patient's death by means of fluorescent in situ hybridization.

Truncus arteriosus communis associated with mitral valve and left ventricular hypoplasia without ventricular septal defect: unique combination

A unique case of truncus arteriosus communis associated with mitral valve and left ventricular hypoplasia, but without ventricular septal defect (VSD), is described. The embryology of this anatomy is considered. The neonatal hemodynamics and the clinical implications of this rare combination of defects are discussed.

Truncus arteriosus malformation: a developmental arrest at Carnegie stage 14

The pathogenesis of truncus arteriosus malformation has been ascribed to deficiency of conotruncal ridges, failure to form a pulmonary conus, absence of the aortopulmonary septum, or hemodynamic factors. To re-examine this issue, we reviewed the morphology of 28 hearts with truncus arteriosus malformation and compared the findings to the sequences of cardiogenesis in 351 normal human embryos of the Carnegie Embryological Collection. All malformed hearts had an absent muscular outflow tract (conal) septum. The truncal valve had four commissures and/or raphes, a fused commissure, in seven cases, three in 20, and uncertain status in one. All but one heart had fibrous continuity between the anterior mitral leaflet and the truncal valve. In embryos, the outflow tract was circular and lined by a layer of cardiac jelly early in Carnegie stage 14 but acquired an elliptical configuration and four cushions, with fusion of the two larger, by stage 16. Semilunar valve leaflets form at the downstream end of the cushions. The more frequent occurrence of three rather than four commissures in the truncal valve associated with absence of a conal septum suggests that the embryonic outflow tract failed to acquire an elliptical shape and cushions that could fuse to subdivide the outflow tract and the semilunar valves anatomically. The presence of truncal valve leaflets shows that three or four cushions did form and the usual presence of mitral-truncal valve fibrous continuity supports otherwise normal outflow tract development. We conclude that a failure or delay of the circular outflow tract of early Carnegie stage 14 to acquire the elliptical configuration needed to induce formation of four cushions, two of which fuse to subdivide the outflow tract and semilunar valve primordia, is the cause of truncus arteriosus malformation.

Polysplenia syndrome with common atrioventricular canal and persistent truncus arteriosus

A case of an infant with a rare combination of polysplenia syndrome with common atrioventricular canal and persistent truncus arteriosus is presented. In our present case, severe common atrioventricular valve regurgitation was identified, as in previous cases. To our knowledge, echocardiographic and autopsy findings of this association has not been previously reported. The persistent truncus arteriosus is extremely rare in the setting of the polysplenia syndrome, but the present case report demonstrates that these anomalies may, at times, occur.

Outflow tract abnormalities in atrioventricular canal malformations

Atrioventricular canal malformations are commonly regarded as being arrests of development of normal cardiac septation since their morphology strongly resembles the normal heart of Carnegie stages 14 through 18. Similarly, the spectrum of outflow tract abnormalities, which includes truncus arteriosus, transposition of the great arteries, double outlet right ventricle, and tetralogy of Fallot, has been interpreted as a developmental arrest because these malformations resemble the normal embryonic outflow tract in Carnegie stages 14 through 18, respectively. The causes of the developmental arrests in these two classes of malformations are unknown. Observation of an unusual autopsy case with features of both atrioventricular canal defect and tetralogy of Fallot prompted us to review the outflow tract morphology in 38 hearts with an atrioventricular canal malformation and two semilunar valves to determine if there was evidence to support the idea that both conditions may have the same pathogenesis. In all 38 hearts there was fibrous continuity between an anterior mitral leaflet and an aortic valve, which by anatomic definition means that no case had truncus arteriosus, transposition of the great arteries, or double outlet right ventricle. There were three cases with coarctation of the aorta, a lesion which arises when blood flow in the pulmonary trunk exceeds aortic flow during early development. There were four cases with pulmonary to aortic valve caliber ratios similar to those found in tetralogy of Fallot but the aortic-to-pulmonary valve angle relative to the heart base ranged over the full spectrum of angles seen in normal hearts and those with tetralogy of Fallot. Furthermore, this angle showed the same range of values for partial and complete canal defects, and did not correlate with patient age or ratio of pulmonary to aortic valve caliber. We conclude that the pathogenesis of the spectrum of outflow tract developmental arrests is different from that of atrioventricular canal malformations.

Truncus arteriosus associated with trisomy 18

The spectrum of cardiac anomalies in trisomy 18 typically includes septal defects and polyvalvular disease and only rarely complex malformations. We report the first case of trisomy 18 with truncus arteriosus type II.

A case of common truncus arteriosus with rare cardiac abnormalities

Truncus arteriosus communis is a well-known, congenital, cardiac abnormality. In this report, we describe a very rare variant in which the truncus arose from the right ventricle, the atrial and ventricular septa were intact, the left ventricle was hypoplastic and the small right atrium was draining to the truncus arteriosus through a fibrose tunnel-like connection.

[Truncus arteriosus with an unusual anatomy of the pulmonary arteries: a report of a surgically treated case]

The authors describe the rare case of an infant, 35 days old at operation, with truncus arteriosus in which the right pulmonary artery rose from the left posterolateral side of the truncus arteriosus above the truncal valve, and the left pulmonary artery from the inferior aspect of the proximal third of the aortic arch. At operation, the right ventricle-pulmonary artery continuity was reconstructed with an aortic homograft. The left pulmonary artery was anastomosed "end-to-side" to the left carotid artery of the aortic homograft, and the right pulmonary artery "end-to-side" to the joined openings of the left subclavian artery and descending thoracic aorta. It was difficult to understand if the first tract of the left pulmonary artery (2 mm in diameter) was a true pulmonary artery, a ductus arteriosus or an anomalous vessel. The infant survived the operation. Intensive postoperative treatment was necessary to counteract severe episodes of pulmonary hypertension. Enoximone 5 mcg/Kg/min and prostacyclin 5-10 mcg/Kg/min were effective in reducing pulmonary vascular reactivity. Four month follow-up shows optimal surgical correction and normal hemodynamic findings.

Syndromal associations of common origin of the carotid arteries

The term "common origin of the carotid arteries" (COCA) has been proposed to replace the older terms "origin of the left carotid artery from the innominate stem" and "bicarotid trunk with anomalous right or left subclavian artery." These anatomic patterns are usually reported to occur in about 11% of whites and 20-25% of blacks and have been reported to have increased frequency in patients with esophageal atresia-tracheoesophageal fistula, DiGeorge anomaly, and anomalous origin of the left coronary artery from the pulmonary artery. COCA is a significant, if not invariant, feature of the great arteries in the condition usually called in the more recent literature "anomalous origin of the innominate artery," the most frequent cause of symptomatic tracheal compression by anomalous systemic arteries. Analysis of associations of COCA with various other congenital cardiovascular lesions showed, in addition, significant association with congenital polyvalvular disease, truncus arteriosus, aorticopulmonary window, trisomy 13, 18, and 21 syndromes, acrocephalosyndactyly (especially Apert syndrome), tetralogy of Fallot not associated with DiGeorge anomaly, and clinical Noonan phenotype. Pentalogy of Cantrell was associated with no increase in incidence of COCA.

Persistent truncus arteriosus--an autopsy study of 16 cases

Sixteen specimens of heart with persistent truncus arteriosus were studied to evaluate the anatomic features. Using the Collet and Edwards classification, type I truncus arteriosus was the most frequent (62.5%). Using Van Praagh's classification type A1 was the most common (43.7%). There were two cases which could not be classified according to the Collet and Edwards classification. The truncal valve was tricuspid in 75% of the cases and bicuspid in the remaining 25%. In all 6 cases with interruption of the aorta, the truncal valve was committed to the right ventricle. The ventricular septal defect was subtruncal in all except 1 case. There was variation in the thickness of the posterior limb of the septal band and the ventriculo-infundibular fold. Absence of the ventriculo-infundibular fold in 3 cases led to truncal tricuspid continuity. Right-sided aortic arch and interruption of the aorta were frequently associated arch anomalies.

The role of coronary artery abnormalities in the prognosis of truncus arteriosus

A high incidence of coronary ostial and arterial abnormalities was found in a study of 30 pathologic specimens of classic truncus arteriosus at Children's Hospital of Pittsburgh. The following were of special note: (1) left coronary ostium in a posterior and high position; (2) close relation of the left coronary ostium to the pulmonary artery segment in three-leaflet truncal valves; (3) stenosis of the coronary ostium caused by small size, slitlike shape, or the location of the ostium above or in a commissure; (4) the acute angle takeoff of the coronary artery; (5) the position of the left anterior descending artery as it courses posteriorly and close to the truncal wall, and then to the left of the interventricular septum; (6) the size and course of the conal and diagonal arteries from the right coronary artery across the right ventricular outflow area; (7) other coronary abnormalities, including a single coronary artery or ostium with branches crossing the right ventricle below the truncus, the circumflex arising from the right coronary artery and coursing behind the truncus, and the right coronary artery originating from the left anterior descending artery and vice versa. Eight heart specimens with conduit repair were reviewed, and all had injury to coronary arteries, possibly responsible for or contributing to the deaths of six of the eight patients. Coronary abnormalities, often several occurring in combination, may contribute to high operative mortality rate and may be a cause of late sudden death in truncus arteriosus. Surgical procedures should be planned with a view to protecting coronary arteries in the region of the right ventricular outflow tract below the truncus. Coronary artery obstruction (ostial or luminal) can occur and may need to be addressed as a separate issue during surgical procedures.

The conduction system in truncus arteriosus and its surgical significance. A study of five cases

Atrioventricular block may occasionally occur after surgical correction of truncus arteriosus. We therefore studied the conduction system by means of serial sections in five cases of truncus (one after surgical intervention) to delineate the course of the conduction system and its relationship to the ventricular septal defect and the membranous septum. In general, the ventricular septal defect is in the anterior septum, confluent with the truncus, and the atrioventricular bundle is posterior and unrelated to the rim of the ventricular septal defect. In cases in which the ventricular septal defect is anterior and separated from the membranous septum by distinct muscle, the ventricular septal defect can be surgically closed without injury to the atrioventricular bundle. If the ventricular septal defect is related to the membranous septum, the atrioventricular bundle may be close to the ventricular septal defect and susceptible to surgical injury. If muscle separates the ventricular septal defect from the membranous septum, the branching bundle is close to the ventricular septal defect and also is susceptible to surgical injury. In one operated case there was partial dissolution of the left bundle branch, and the right bundle branch was involved in surgical closure of the defect. In summary, in truncus the conduction system varies in its course and is related to the location of the ventricular septal defect and its relationship to the membranous septum. The ventricular septal defect may be close to or related to the membranous septum, and the atrioventricular bundle and the beginning of the bundle branches may be vulnerable to surgical injury.

Calcium currents in hearts with persistent truncus arteriosus

We have used the neural crest model of defective heart development to characterize both L- and T-type Ca2+ currents (ICa,L and ICa,T) in ventricular myocytes from embryonic chick hearts with a severe outflow tract anomaly known as persistent truncus arteriosus (PTA). Because of smaller whole embryo weights but no significant change in the weights of ventricles with PTA, the ventricle to whole embryo weight ratios from hearts with PTA were 61% larger than normal at day 11 of incubation. There was a 51% reduction in the peak magnitude of ICa,L at a test potential of +10 mV (-1.4 vs. -0.7 microA/cm2), whereas ICa,T, a proportionately large fraction of the total Ca2+ current in the embryonic chick ventricle, was unaffected. In comparison to sham-operated controls, ICa,L was otherwise not different. Half-activation occurred at about -1 and -41 mV, whereas half-inactivation occurred at -19 and -61 mV for ICa,L and ICa,T, respectively. The time for half-recovery from inactivation were not different and were 200 and 230 ms for ICa,L and ICa,T, respectively. The time for half-decay of the currents and their responses to BAY K 8644 were also similar in both sham-operated and experimental hearts. Although the dihydropyridine receptor binding experiments suggest that the total number of L-type Ca2+ channels was not different, the results from the physiological experiments indicate that the number of functional L-type channels available for opening and/or the single-channel conductance may be reduced in hearts with PTA. Finally, our results with the neural crest model indicate that it is unlikely that the development of Ca2+ currents is influenced by the onset of cholinergic innervation in the heart.

Cardiovascular anomalies in chick embryos produced by bis-diamine in dimethylsulfoxide

N,N'-bis(dichloroacetyl)-1,8-octamethylenediamine(bis-diamin e) (100 micrograms) dissolved in dimethylsulfoxide (DMSO) was administered to early developing chick embryos (Hamburger-Hamilton stage 9-21) in order to clarify the teratogenic effects on the cardiovascular system and to determine whether bis-diamine interferes with the migration of neural crest cells. Of 346 cases, 154 (44.5%) survived. The incidence of cardiovascular anomalies was 149 out of 154 cases (96.8%). Infundibular ventricular septal defect, double outlet right ventricle, and persistent truncus arteriosus were the primary cardiac anomalies observed in this study. A high percentage of these anomalies were accompanied by hypoplasia of the right 6th aortic arch artery and persistent left 4th aortic arch artery. Particularly, administration of bis-diamine to chick embryos at stage 13 resulted in a high incidence of persistent truncus arteriosus (64.3%). Bis-diamine has been suspected to inhibiting the migration of neural crest cells. However, neural crest cells were observed in the tunica media of the great arteries and the truncal valves of persistent truncus arteriosus produced by bis-diamine in chimeric embryos at stage 13. Morphological changes such as cell death were not observed.

Tricuspid atresia: association with persistent truncus arteriosus

Clinical, echo-Doppler, and pathologic data of a rare case of tricuspid atresia in association with truncus arteriosus are presented. There are only six patients (including the patient reported here) with this anomaly in whom detailed pathologic and/or clinical descriptions are available in the literature. An additional six cases were mentioned in the literature but without any details. A prevalence rate of 1.4% among tricuspid atresia cases is estimated. All infants presented with symptoms of cyanosis and/or congestive heart failure within a few days to 2 months after birth and died shortly thereafter. Cardiomegaly and increased pulmonary vascular markings on the chest x-ray film and left axis deviation with left ventricular hypertrophy on the ECG are usually present. Echocardiographic, catheterization, and angiocardiographic studies are helpful in documenting anatomic and physiologic features of this anomaly. Pathologically, the muscular type of tricuspid atresia, type I or II truncus arteriosus, a large subtruncal VSD, and a hypoplastic right ventricle are present. It is concluded that coexistence of tricuspid atresia and truncus arteriosus is rare; clinical, laboratory, and pathologic features are distinctive; the clinical presentation early in life with rapid demise is common; and prompt palliative surgery immediately after recognition of this anomaly should be undertaken.

Morphogenetic considerations on congenital malformations of the outflow tract. Part 1: Common arterial trunk and tetralogy of Fallot

On the basis of our recent embryologic work concerning the separation process of the outflow tract, together with our study of the morphology of specimens from the Leiden Collection of malformed hearts, we have reconsidered, in conjunction with the pertinent literature, the morphogenesis of common arterial trunk and tetralogy of Fallot. The constant characteristics of common arterial trunk, namely a common trunk, a common arterial orifice and a ventricular septal defect, can be explained simply by absence of the aorto-pulmonary septum, or its complete failure to contribute to the process of separation. The nature of the variable morphologic features, however, is not always clear. Presence of such variation is not contradictory to the explanation of the main characteristics in this malformation. Tetralogy of Fallot, in contrast, can be considered to result from anterior displacement of the columns of the aorto-pulmonary septum relative to the outlet segment and its proximal boundary, the primary fold. Our findings, and suggestions, diverge considerably from conventional theories concerning the morphogenesis of these malformations.

Associated occurrence of persistent truncus arteriosus and asplenia

An infant with persistent truncus arteriosus associated with splenic agenesis and the asplenia syndrome is reported, including clinical, echocardiographic and autopsy findings. To the authors' knowledge this association has not been previously reported.

Transesophageal echocardiography in aortopulmonary communications

The assessment of congenital aortopulmonary communications by transthoracic echocardiography may be suboptimal, particularly postoperatively, due to limited acoustic windows. We performed intraoperative transesophageal echocardiograms in six patients with eight proven systemic-pulmonary communications. Diagnosis included truncus arteriosus (1), aortopulmonary window (1), Waterston anastomosis (3), central Gore-Tex shunt (1), and modified left Blalock-Taussig shunt (2). All communications were accurately demonstrated by transesophageal echocardiography (TEE). The transesophageal technique also provided an assessment of the size of the aortopulmonary communications and the proximal pulmonary arteries. In addition, the gradient across some of the communications could be accurately estimated utilizing the high pulse repetition frequency Doppler. On the other hand, only two of the seven aortopulmonary communications were detected by transthoracic echocardiography. Postoperatively, transesophageal imaging demonstrated unobstructed conduit in five of five patients who underwent conduit repair, as well as intact closure of aortopulmonary communications and concomitant closure of ventricular septal defects.

Coronary arteries in truncus arteriosus

The origin and distribution of the coronary arteries was described in 39 autopsy specimens of truncus arteriosus (TA). The specimens were classified according to the number and the patterns of the truncal cusps. The position of the truncal cusps was defined in relation to intracardiac structures, namely, the atrioventricular orifices. Bicuspid truncal valves were observed in 8 cases (21%), tricuspid in 22 cases (56%) and quadricuspid in 9 cases (23%). All tricuspid valves had 2 anterior and 1 posterior cusp. Great variability in the origin of the coronary arteries was observed, with a tendency for the right coronary artery to arise from the anterior right quadrant and for the left coronary artery to arise from the anterior and left quadrant. Such a tendency was observed in 50% of the bicuspid, in 59% of the tricuspid and in 66% of the quadricuspid valves. The anatomic right ventricle was always observed to be vascularized by a right coronary artery, and the anatomic left ventricle by a left coronary artery, even in cases in which there was a single coronary trunk. The anterior surface of the right ventricle was crossed by a right coronary artery in 5 cases. A single coronary artery was observed in 7 cases (18%). Embryologic considerations are offered, especially regarding the relation between the observed variability in coronary artery patterns in TA and the absence of the truncal septation.

Coronary arterial and sinusal anatomy in hearts with a common arterial trunk

Eighty-four specimens of common arterial trunk were studied with special reference to the arrangement of the leaflets in relation to the atrioventricular valves, the origin of the coronary arteries in relation to the arterial sinuses, and the epicardial course of the coronary arteries. Fourteen normal hearts were used for comparison. In the hearts with common arterial trunk, the location and level of the coronary artery orifices (as well as the relationship of the truncal root to the area of fibrous continuity with the mitral valve) are different from those in normal hearts. In none of the hearts with common arterial trunk (particularly the 53 hearts with three leaflets in the truncal valve) did the appearance of the truncal valve approximate that of a normal aortic valve. Among the 22 hearts with four leaflets, there was a high incidence of coronary artery orifices in opposite sinuses (17/22 or 77.3%) and a low incidence of coronary artery orifices in adjacent sinuses (2/22 or 9.1%). These results suggest that the formation of the truncal valve is independent of the formation of the coronary orifices. Its leaflets are not predestined to become part of either the aortic valve or the pulmonary valve.

The angiocardiographic diagnosis of a persistent truncus arteriosus in a foal

Persistent truncus arteriosus is a relatively rare cardiac anomaly which is associated with a single large artery arising from the ventricles. An interventricular septal defect is invariably present. The vessel gives origin to the pulmonary trunk, aorta and coronary arteries. A description of the angiocardiographic diagnosis of this condition is given as well as a general review of the relative developmental anatomy.

Cardiovascular anomalies produced by nimustine hydrochloride in the rat fetus

The cardiovascular teratogenicity of nimustine hydrochloride (ACNU) was studied in rat fetuses. This drug is a nitrosourea derivative anticancer agent and produces alkylation of DNA. Pregnant Donryu rats were treated with single doses of 10, 11 or 13 mg/kg of the teratogen at various stages during gestation. Examination of the hearts was performed by microdissection after sacrificing the animals on the 20th day of gestation. The highest frequency of cardiovascular anomalies was found in the groups treated on the 8th day of gestation, but there was no difference in the rates induced by the three dosages of ACNU administered. The most common cardiovascular anomalies observed were ventricular septal defect (76.8%) and double outlet right ventricle (10.3%). A considerable number of affected fetuses (37/263) showed complex cardiac anomalies with atrioventricular (AV) malalignment and other AV valve anomalies. These anomalies include: double inlet left ventricle, straddling AV valve, atresia or stenosis of the AV valve, and dysplastic AV valve. ACNU appears to be a useful teratogenic agent for inducing complexes of cardiac anomalies which include AV malalignment.

Common arterial trunk with pulmonary atresia

We describe a congenitally malformed heart with usual atrial arrangement and concordant atrioventricular connexions in which a solitary arterial trunk left the base of the heart and supplied the coronary and systemic arteries. Pulmonary blood supply was derived from systemic to pulmonary collateral arteries but, in addition, hypoplastic intrapericardial pulmonary arteries were found in each lung hilum. The two sets of hilar arteries were discontinuous, but it seemed likely that this discontinuity had been artefactually produced by prior dissection. Irrespective of this matter, the left pulmonary arteries were connected by a thread-like atretic cord to the left-sided sinus of the solitary arterial trunk. This indicates that, initially, there had been a common trunk which now demonstrates pulmonary atresia. The significance of this lesion is discussed in the light of the nomenclature and description of hearts with common arterial trunk.

Spectrum of Di George syndrome in patients with truncus arteriosus: expanded Di George syndrome

A study of 26 patients with truncus arteriosus showed a high prevalence of facial dysmorphism, aortic arch abnormalities, extracardiac malformations, and significant prenatal risk factors. There was little evidence of parathyroid or thymic abnormalities. However, there was laboratory evidence of immune deficiency, especially T-helper lymphocytes, and clinical evidence of predilection to infection. These findings suggest that patients with truncus arteriosus belong to the spectrum of the Di George syndrome.