Aortic Junction Research Articles

NOT JUST A SIMPLE FEVER: DIAGNOSIS OF COMPLICATED INFECTIVE ENDOCARDITIS ON BICUSPID AORTIC VALVE IN A YOUNG MAN

Abstract Bicuspid aortic valve is the most common form of congenital heart disease (prevalence of 0.5 to 2.0%). These patients develop infective endocarditis at significantly higher rates than the general population; furthermore, they are at increased risk of developing infective endocarditis at a younger age owing to intrinsic factors of the aortic valve, but demonstrate better long–term survival after surgical treatment. This case report concerns a 33–year–old caucasian man who presented to the emergency department for persistent fever. He had no significant past medical history, except for a known bicuspid aortic (type 0) valve. The laboratory test demonstrated an active infection and blood cultures were positive, so we performed a transthoracic echocardiogram showing a mobile mass on the aortic valve, associated to a severe aortic regurgitation. Hence, we decided to perform a transesophageal echocardiogram that documented a bicuspid aortic valve with an extensive endocarditic vegetation on anterior leaflet, cusp prolapse and a non–homogenous peri–valvular area, involving the mitral–aortic junction, compatible with abscess. Perivalvular extension of infective endocarditis is the most frequent cause of uncontrolled infection and is associated with a poor prognosis so, as suggested by ESC Guidelines, this clinical case represented an indication for early surgery. The patient was transferred to cardiac surgery department where he underwent surgery. Extensive debridement of the endocarditic lesion was performed; the mitral–aortic junction was reconstructed by suturing a double patch of heterologous pericardium. The defect resulting from the debridement beneath the left coronary ostium was also reconstructed using an additional sutured pericardial patch; then, an Inspiris Resilia size 23 prosthesis was implanted. Transesophageal echocardiography revealed good functioning of the aortic valve prosthesis with mild mitral insufficiency. Meanwhile, blood cultures resulted positive for Staphylococcus Aureus coagulase–negative, so specific antibiotic therapy was started.

P194 DESTRUCTIVE AORTIC VALVE ENDOCARDITIS WITH INVOLVEMENT OF THE MITRO–AORTIC CURTAIN: A SUCCESSFUL “UFO” PROCEDURE

Abstract Infective endocarditis is a relatively rare disease with an estimated mean incidence of 3.6–7.0 cases per 100,000 subject–years. Aortic bicuspid disease, the most frequent congenital anomaly, is one of the main risk factors. Heart failure, uncontrolled infection (fistulas, abscesses, persistently positive blood cultures) and systemic embolization are among the most feared complications of endocarditis: these cases constitute an indication for emergency/urgent cardiac surgery. An example of extremely demolitive surgery is the Commando or "UFO" procedure, which consists in the double replacement of the aortic valve and the mitral valve with reconstruction of the mitro–aortic junction. The clinical case concerns a 36–year–old man who went to the emergency room for high fever with shivering. Having been found positive blood cultures for MSSA and having emerged mitro–aortic vegetation by echocardiogram, a diagnosis of infective endocarditis was made. During hospitalization, multi–organ cardioembolic phenomena (e.g. splenic, cerebral) with hemorrhagic cerebral infarction occurred: therefore, in accordance with current guidelines, a conservative treatment was temporarily opted for. However, in the following days the deterioration of the clinical–haemodynamic picture was such as to require emergency cardiac surgery. The patient was thus subjected to Commando or UFO procedure with reconstruction of the mitral–aortic junction. Severe bi–ventricular dysfunction was found for the first time at post–operative echocardiographic control, with the need for mechanical support to the circulation (AV ECMO, Impella). The remainder of the hospitalization was characterized by a progressive recovery of ventricular function (LVEF 16% to 44%), therefore patient was discharged in discrete hemodynamic compensation, despite the multiorgan sequelae (hepatic, neurological, renal).

Flow disturbance around dynamically interacting aortic junctions

Flow disturbance around dynamically interacting aortic junctions

Successful endovascular coil embolization of large pseudoaneurysm of ductus arteriosus diverticulum

BackgroundPseudoaneurysm of the ductus arteriosus diverticulum, although rare in adults, may have catastrophic consequences if left untreated due to erosion and rupture of the pseudoaneurysm into adjacent thoracic structures. Although thoracic endovascular aortic repair (TEVAR) is the standard treatment method for aneurysm closure of the ductus arteriosus diverticulum, it was not possible in our patient secondary to marked aortoiliac access vessel tortuosity, significant vascular calcific burden, and an abdominal aortic aneurysm. We describe the first reported case of endovascular coil embolization being successfully used as the definite repair of a ductus arteriosus diverticulum pseudoaneurysm.Case presentationAn 85-year-old man with history of severe coronary arterial disease presented with an enlarging pseudoaneurysm of a ductus arteriosus diverticulum. The diverticulum and thoracic aortic junction demonstrated the typical obtuse angles and wide neck, differentiating it from otherwise similar-appearing diagnostic considerations. Repair was attempted with conventional aortic stent graft but the patient’s infrarenal abdominal aortic aneurysm and his heavily calcified, tortuous iliac vessels could not accommodate the 24Fr introducer sheath necessary for stent graft placement. Therefore, endovascular coil embolization was successfully completed through a 4Fr directional catheter. The patient tolerated the procedure well and was discharged from the hospital in good condition on post-embolization day six.ConclusionsEndovascular coil embolization is an alternative treatment for ductus arteriosus diverticulum pseudoaneurysm closure in cases where the standard TEVAR method is unsuccessful. Instead of the wide entry point at the aorta we used the junction of the diverticulum and pseudoaneurysm as the “neck” for satisfactory and stable coil placement. Endovascular coil embolization alone may be a viable definitive therapy for occlusion of the ductus pseudoaneurysm component of the diverticulum in cases where complex anatomy or extensive vascular disease makes stent graft repair impractical if not impossible.

Location and Size of Coronary Ostia in Normal Autopsied Hearts at the University Teaching Hospital, Lusaka, Zambia

Background: Coronary ostia are orifices located in the aortic sinuses from which coronary arteries normally arise. Knowledge of their location and size is important in diagnosis and treatment cardiovascular diseases. Materials and methods: A total of 125 hearts were dissected and examined during autopsy to determine the size and location of the coronary ostia in the aortic sinus, sinu-tubular junction (STJ) or tubular part of the ascending aorta. Photographs of coronary ostia were taken and a Vernier caliper was used to measure ostia. Results: The right coronary ostium was located in the right aortic sinus 79.3% (96/121) and on the STJ in 20.7% (25/121) of the hearts. The left coronary ostium was located in the left aortic sinus in 73.6% (89/121) and on the STJ in 26.4% (32/121) of the hearts. The left coronary ostium width range was 1.6 – 7.9 mm (4.62 ± 1.104 mm) and the height range was 1.5 – 4.9 mm (2.64 ± 0.719 mm). The right coronary ostium width range was 1.6 – 9.6 mm(3.66 ± 1.40 mm) and the height range was 1.1 – 4.9 mm (2.27 ± 0.72 mm).The estimated mean cross sectional area of the left coronary ostium was 9.70 mm2 and that of the right was 6.99 mm2 . The left coronary ostium was significantly larger in size than the right with a p-value < 0.05 when their means were compared using the t-test. Conclusion: The majority of coronary ostia were located in their respective aortic sinuses below the sinutubular junction. Knowledge of the location of coronary ostia in the ascending aorta is important during angiography and surgery around the aortic root.

Measuring aortic valve coaptation surface area using three-dimensional transesophageal echocardiography

As aortic valve (AV) repairs become more sophisticated, surgeons need increasingly detailed information about the structure and function of this valve. Unlike two-dimensional transesophageal echocardiography (2D-TEE), using three-dimensional (3D)-TEE makes it possible to image the entire AV. We hypothesized that measuring coaptation surface area (CoapSA) would be feasible and reproducible, and CoapSA would decrease in patients with aortic insufficiency. We developed a new technique to calculate the AV-CoapSA using 3D-TEE. We measured the coaptation surfaces between the right coronary cusp/left coronary cusp, right coronary cusp/non-coronary cusp, and left coronary cusp/non-coronary cusp in ten normal AVs and ten AVs with moderate-severe aortic insufficiency (AI). Since computer models have previously shown that CoapSA is trapezoidal, we used the formula: trapezoid area = length × (medial coaptation height + lateral coaptation height)/2. The total CoapSA was calculated by adding all three areas. To adjust for valve size, we indexed the value to the diameter of the ventricular aortic junction (VAJ). Measurements were performed by two observers. The intra-observer correlation was 0.84 for one observer (P < 0.0001) and 0.93 for the other (P < 0.0001). The inter-observer correlation was 0.87 (P < 0.0001). In normal valves, the CoapSA [mean total (standard deviation)] was significantly greater than in the insufficient valves [1.61 (0.31) cm(2) vs 1.03 (0.22) cm(2), respectively; P < 0.001]. After indexing for the VAJ diameter, the total CoapSA remained significantly greater in normal valves than in insufficient valves. In this proof of concept study, we present a new and innovative technique to measure AV-CoapSA using 3D-TEE. It is reproducible and shows decreased CoapSA in patients with AI. Coaptation surface area may provide insight into mechanisms of AI and may have predictive value following AV repair.

Repair of Dilated Aortic Root and Sinotubular Junction Using a Stabilizer Ring

Aortic root aneurysm and dissection are potentially life-threatening conditions that involve a structural weakness of the aortic wall. Management of aortic root aneurysm (with or without aortic insufficiency) has recently been the subject of much scholarly discussion which resulted in some modifications. The current trend is a valve-sparing root repair or replacement as well as preserving or restoring the diameter of the aortic annulus and sinutubular junction. This manuscript reviews the etiology and diagnosis of aortic root aneurysm or dilated aortic annulus as well as a novel treatment approach. A newly patented apparatus that restores and repairs the aortic annulus and sinotubular junction is reviewed.

Late calcification of the mitral–aortic junction causing transient complete atrio-ventricular block after mediastinal radiation of Hodgkin lymphoma: Multimodal visualization

Complete atrio-ventricular (AV) block etiology may be either functional (autonomic, metabolic/endocrine disease or drug-related), which tends to be reversible, or structural, characterized by fibrosis of myocardial conduction tissue and often related to acute and chronic coronary artery disease, infectious disease (Lyme, Chagas disease), congenital heart disease, inflammatory disease (systemic lupus erythematosus, rheumatoid arthritis), infiltrative disease (amyloidosis, sarcoidosis, hemochromatosis), cancer (lymphoma, mesothelioma, melanoma), and radiation therapy [1].

In vitro hemodynamic investigation of the embryonic aortic arch at late gestation

This study focuses on the dynamic flow through the fetal aortic arch driven by the concurrent action of right and left ventricles. We created a parametric pulsatile computational fluid dynamics (CFD) model of the fetal aortic junction with physiologic vessel geometries. To gain a better biophysical understanding, an in vitro experimental fetal flow loop for flow visualization was constructed for identical CFD conditions. CFD and in vitro experimental results were comparable. Swirling flow during the acceleration phase of the cardiac cycle and unidirectional flow following mid-deceleration phase were observed in pulmonary arteries (PA), head-neck vessels, and descending aorta. Right-to-left (oxygenated) blood flowed through the ductus arteriosus (DA) posterior relative to the antegrade left ventricular outflow tract (LVOT) stream and resembled jet flow. LVOT and right ventricular outflow tract flow mixing had not completed until ∼3.5 descending aorta diameters downstream of the DA insertion into the aortic arch. Normal arch model flow patterns were then compared to flow patterns of four common congenital heart malformations that include aortic arch anomalies. Weak oscillatory reversing flow through the DA junction was observed only for the Tetralogy of Fallot configuration. PA and hypoplastic left heart syndrome configurations demonstrated complex, abnormal flow patterns in the PAs and head-neck vessels. Aortic coarctation resulted in large-scale recirculating flow in the aortic arch proximal to the DA. Intravascular flow patterns spatially correlated with abnormal vascular structures consistent with the paradigm that abnormal intravascular flow patterns associated with congenital heart disease influence vascular growth and function.

Aorto–Atrial Fistula: An Important Complication of Aortic Prosthetic Valve Endocarditis

Aorto–Atrial Fistula: An Important Complication of Aortic Prosthetic Valve Endocarditis

Aortic dimensions in Turnerʼs syndrome: two-dimensional echocardiography versus magnetic resonance imaging

Patients with Turner's syndrome have an increased risk of cardiac death caused by aortic disease. Consensus has not been reached about the best method to image the aorta in this syndrome. This present study aimed: (i) to evaluate thoracic and abdominal aortic dimensions by two-dimensional echo (2-DE) and magnetic resonance imaging (MRI) and (ii) to assess agreement between 2-DE and MRI measurements. Among 75 kariotypically proven Turner's syndrome patients, 59 (79%) (mean age: 22 +/- 7 years) underwent a 2-DE and an MRI study of the thoracic and proximal abdominal aorta. The aortic root (AR), the sino-tubular aortic junction (STJ), the first part of the ascending thoracic aorta (AscTA), the aortic arch (AArch), the descending thoracic aorta (DTAp) a few centimetres below the isthmus and the abdominal aorta (AbA) were analysed. The Bland and Altman method and Lin's concordance correlation coefficient were utilized to compare 2-DE and MRI aortic dimensions. Compared to MRI, feasibility of aortic imaging by 2-DE was identical at AR level, but lower when measuring distal aorta (88% at DTAp and 91.5% at AbA level versus 100%). The 2-DE and MRI showed a very slight difference between measurements and a high concordance correlation coefficient at the level of AR and AscTA; correlations were weaker at the other aortic levels. Absolute differences calculated at each measurement level showed that concordance (defined as differences within 1 mm between 2-DE and MRI absolute measures) was highest at AR (45.6%) and AscTA (28%) level and lowest at STJ (12.2%) level. The 2-DE overestimated aortic arch diameters in approximately 70% of cases, whereas at the remaining aortic levels MRI measurements were usually 1 mm higher compared to the corresponding 2-DE values. Concordance between 2-DE and MRI was found to be very good at the AR and AscTA levels. Because the risk of aortic complication is higher when AR and proximal thoracic aorta are dilated, 2-DE may be considered a useful method to screen for aortic disease and a good choice to follow proximal aortic dimensions over time in Turner's syndrome patients.

Novel stent system for accurate placement in aorto-ostial renal artery disease: preclinical study in porcine renal artery model

Treatment of aorto-ostial renal artery stenosis has been associated with a lower procedural success and higher complication and restenosis rate, as compared to nonostial lesions. The design and delivery of currently available stent systems in ostial lesions can result in inaccurate stent positioning and placement leading to stent protrusion into the parent vessel lumen or geographic miss. A novel stent system (SquareOne Inc., Campbell, CA, USA) has been designed specifically for aorto-ostial lesions in the renal artery. This stent system aims to provide both tactile and visual confirmation of the ostium at the aorta, allow for improved accuracy during stent positioning and placement, provide complete scaffolding of the lesion at the aortic junction to the native vessel, and enable future vessel reaccess. Stents (n=12) were implanted in both renal arteries of six swine. For histology, two animals were euthanized immediately after stent implantation, and each two animals were then followed up at 2 and 4 weeks, respectively. Intravascular ultrasound (IVUS) studies were performed immediately after stent implantation and at follow-up. Proper stent positioning and implantation was obtained in all animals. Angiographic and IVUS assessments indicated no dissection or thrombus formation. Histology demonstrated good apposition and endothelialization of the stent strut surface. The unique flared shape of this novel ostial stent system allows for improved accuracy during stent positioning and placement, as well as complete apposition and coverage/scaffolding of the similarly-shaped luminal ostium. Future studies will determine if this novel stent system fulfills the unmet clinical need in aorto-ostial stenoses.

Prospective Evaluation of Aortic Dimensions in Turner Syndrome: A 2-Dimensional Echocardiographic Study

The prevalence of aortic disease, including dilatation of the proximal aorta, is higher in patients with Turner syndrome (TS) compared with healthy female control subjects, but there are no data regarding the prospective evaluation of aortic dimensions in this syndrome. This study was undertaken to assess the: (1) prevalence of aortic root (AR) and proximal thoracic aorta enlargement by 2-dimensional echocardiography; and (2) evolution of aortic diameters over time. In all, 78 patients with kariotypically proven TS (mean age 21.5 +/- 9 years) underwent a 2-dimensional echocardiographic study of the proximal thoracic aorta at baseline and yearly thereafter, during a median follow-up period of 37 months (25th-75th percentile: 25-51). We investigated the AR, sinotubular aortic junction, and tubular portion of the ascending thoracic aorta. Linearity of the relationship between AR dimensions and body surface area allowed us to use Roman nomograms to identify patients with or without an enlarged AR. At baseline, 62 of 78 patients (80%) presented normal AR dimensions compared with 16 of 78 (20%) with AR dilatation. Mean AR diameter was 24.5 +/- 3.6 versus 30.9 +/- 4.6 mm (P = .0001), sinotubular aortic junction was 18.0 +/- 4.0 versus 21.7 +/- 5.2 mm (P = .015), and ascending thoracic aorta was 21.1 +/- 4.1 versus 26.6 +/- 6.0 mm, respectively (P = .003). The incidence of AR dilatation was similar in patients younger than 18 years or 18 years and older. During follow-up, we observed a similar significant, albeit minor, increase in aortic diameters in all patients. However, the absolute entity of this increase was not clinically relevant. Lymphedema at birth was the only significant clinical variable observed more frequently in patients with AR enlargement compared with those with normal AR. Proximal aortic dimensions in patients with TS did not change rapidly in our medium-term follow-up study. The progression of AR dimensions was similar in patients with (20%) or without baseline AR dilatation. Age did not affect the pattern and evolution of aortic disease in TS.

691 Intracardiac echocardiography for conservative aortic valve surgery: A new investigative tool

Background: Dilation of aortic annulus and sino-tubulaire junction (STJ) is a characteristic lesion of dystrophic aortic insufficiency. A standardized approach of conservative aortic valve surgery has been suggested using external expansible aortic ring. Intracardiac Echocardiography (ICE) was used to study aortic root dynamics before and after conservative aortic valve surgery on an ovine model. Methods: Six sheeps underwent a double sub and supravalvular annuloplasty, performed by the implantation of 2 expansible rings, at the level of the aortic annular base (22 mm ring) and sino-tubular junction (STJ, 18 mm ring). Imageswere obtained using ICE (AcuNav®, Siemens) with high resolution probe (5 to 10 MHz), introduced through the left internal jugular vein into the right atrium. Coaptation height and expansion of the aortic root were studied. Results: Aortic root parameters were analyzed before (B) and after (A) the implantation of the expansible prosthetic rings (table 1), which produced significant reduction of annulus and STJ diameters, respectively -36.5% and -33.9%, without significant gradient. ICE allowed good visualization of valvular coaptation, with a mean coaptation height of 0.27±0.07 cm pre-implantation and 0.46±0.07 cm after implantation (p<0.001). Conclusion: Implantation of expansible aortic ring prosthetic ring reduces aortic annulus and STJ diameters, increases leaflet coaptation area while preserving aortic root expansibility. ICE provided a precise analysis of aortic root dynamics in an ovine model. It might be an interesting tool to assess the properties of the aortic root after valve repair for dystrophic aortic insufficiency

Significance of Reverse Orientation of the Ductus Arteriosus in Neonates With Pulmonary Outflow Tract Obstruction for Early Intervention

Reverse orientation of the ductus arteriosus (RDA), defined as an inferior angle at the aortic junction of <90 degrees , is associated with pulmonary atresia; however, the significance of RDA in nonatretic pulmonary outflow tract obstruction (POTO) is unknown. The purpose of this study was to evaluate the relation between ductal morphology and the need for early intervention. Ductal morphology was retrospectively reviewed in 76 neonatal cases of POTO. Patients were stratified to those with conotruncal (CT) or primary pulmonary valve (PV) abnormalities. The prevalence of RDA was 40 of 68 (59%) and was higher in patients with CT defects (28 of 30, 93%) compared with PV abnormalities (12 of 38, 32%; chi-square = 26.4, p <0.0001). Early intervention was required in 29 of 40 patients with RDA (73%) compared with only 8 of 28 patients with normal ductal morphology (31%; chi-square = 12.8, p <0.001). The proportion of patients with RDA who required early intervention was greater in PV abnormalities (12 of 12, 100%) compared with CT defects (17 of 28, 61%; chi-square = 6.5, p <0.02). Importantly, after excluding patients with pulmonary atresia, these analyses were unchanged. In patients with nonatretic POTO, a threshold inferior angle of 65 degrees was predictive of the need for early intervention. RDA in patients with PV abnormalities, or CT defects and an inferior angle <65 degrees , is a specific indicator for early intervention. These findings demonstrate an association between RDA in the context of atretic and nonatretic POTO and the need for early intervention. The need for early intervention should be considered when RDA is identified in this population.

Laparascopic aortic reinforcement and endovascular graft replacement

Purpose. The purpose of this study is to evaluate the feasibility of using an external aortic wrap in conjunction with an endovascular graft and to examine the histological response. Methods. Six female pigs, 56–84 kg, underwent laparoscopic retroperitoneal placement of homemade aortic wraps made of Dacron fabric and specially designed straps just below the renal arteries. One week later, stents (one 12 mm × 4 cm Wallstent, two 308 Palmaz stents) were inserted into the infrarenal aorta for preliminary experiments in three pigs, and stent-grafts (13 mm × 5 cm Viabahn) were placed in three pigs. The stents and stent-grafts were aligned with the proximal edge of the aortic wrap, and the balloon was expanded. One animal was prematurely sacrificed. The pigs were followed for 1 to 3 weeks in stent models and for 4 weeks in stent-graft models. The animals were then sacrificed, and abdominal aortas were harvested for histological examination. Results. Technical success was achieved in all animals without complications. One animal was prematurely sacrificed due to cerebral edema secondary to anesthesia. Laparoscopic operative time was 2:42 ± 0:47, and 0:43 ± 0:15 for stent placement. Gross examination of the samples revealed fibrosis external to the device at 1- and 3-week time-points; by 3 weeks the wrap was partially incorporated into the adventitia. Stents and stent-grafts were well incorporated into the intima and no migration was observed. Histological examination of all samples revealed a foreign-body response. Sections taken from beneath the device edges revealed necrosis localized to the muscularis and adventitial aortic junction; however, sections taken from beneath the device body showed no signs of necrosis and the vasa vasorum of the aortic wall was intact. Conclusions. Coordinate laparoscopic external aortic wrapping and stent-grafting is feasible in a porcine model. Aortic wall necrosis was limited. This adjunct to endovascular graft repair of abdominal aortic aneurysms may enhance eligibility for patients with large aortic neck and prevent proximal type 1 endoleak.

Body surface area as a predictor of aortic and pulmonary valve diameter

Background: Predicting cardiac valve size from noncardiac anatomic measurements would benefit pediatric cardiologists, adult cardiologists, and cardiac surgeons in a number of decision-making situations. Previous studies correlating valve size with body size have been generated with the use of fixed autopsy specimens, angiography, and echocardiography, but primarily in the young. This study examines the relation of body surface area to measurements of the left ventricular–aortic junction (aortic valve anulus diameter) and the right ventricular–pulmonary trunk junction (pulmonary valve anulus diameter) in 6801 hearts across a wide spectrum of ages. Methods: From June 1985 to October 1998, cardiac valves from 6801 donated hearts were analyzed morphologically. Donor age was newborn to 59 years (mean 31 ± 17 years; median 32 years). Calculated body surface areas ranged from 0.18 to 3.55 m 2. Aortic (n = 4636) and pulmonary valve diameters (n = 5480) were measured from enucleated valves suitable for allograft transplantation. Mean valve sizes were computed for ranges in body surface area in 0.1-m 2 increments. Results: For adult men (age ≥ 17 years), the mean aortic valve diameter was 23.1 ± 2.0 mm (n = 2214) and the mean pulmonary valve diameter was 26.2 ± 2.3 mm (n = 2589). For adult women, the mean aortic valve diameter was 21.0 ± 1.8 mm (n = 1156) and the mean pulmonary valve diameter was 23.9 ± 2.2 mm (n = 1408). The mean indexed aortic valve area was 2.02 ± 0.52 cm 2/m 2 and the pulmonary valve area 2.65 ± 0.52 cm 2/m 2. Between 82% and 85% of the variability was explained by the size of the patient. Regression equations were developed both overall and separately for men and women, although the additional contribution of sex above that of body size was less than 1%. Conclusions: Aortic and pulmonary valve diameters are closely related to body size. Thus, body surface area, when used in conjunction with other clinically accepted evaluations, is a useful tool for estimating normal aortic and pulmonary valve size. (J Thorac Cardiovasc Surg 2000;119:975-82)

Organization of medial elastin at aortic junctions in sheep and lambs.

Aortas from four sheep and three fetal lambs were fixed at physiological pressure in 10% neutral buffered formalin. The regions with branches were serially sectioned in either cross or longitudinal section at 7-micron intervals and stained for elastin with Gomori-aldehyde-fuchsin. A large model of one aortointercostal junction was made from Plexiglas to show that bundles of elastin appeared to be continuous from the aorta into the branch. These bundles were then studied from large photomicrographs of the other junctions. At the intercostals and lumbars, the elastin lamellae ran continuously from the outer third of the media into the branch. There was often an added "pad" of elastin and other acellular material on the flow divider (distal lip). The large muscular branches which arose from the abdominal aorta have much less elastin than the intercostals. In them the aortic elastin appears to merge into a raphe on the proximal and lateral sides of the junction, with a very abrupt transition. A "tongue" of muscle from the branch often penetrated into the media of the aorta distally. Occasionally a small acellular cap was seen on the apex of the flow divider. There were few significant differences between the lambs and the sheep, probably because embryologically the arteries develop very early. The proximal and distal lips of all junctions were easily distinguished from each other, and the small and large branches were also different. We suspect these regions may respond differently to pressure, but we did not test this hypothesis.

Development of the ductus arteriosus in right ventricular outflow tract obstruction.

We studied the morphology of the ductus arteriosus in 14 infants, ages 2--90 days. Eight (group 1) had pulmonary atresia (structural and functional) with an intact interventricular septum; six (group 2) had pulmonary atresia with a ventricular septal defect. The inferior angle of the ductus arteriosus at the aortic junction was measured in each patient. In group 1, this angle was obtuse in all but one patient. In group 2, the angle was acute in all. Further study of intracardiac anatomy suggested that in group 1, the obtuse inferior angle of the ductus arteriosus was the result of a late and progressive obstructive phenomenon that allowed normal right-to-left flow through the ductus arteriosus during much of fetal life. In group 2, the direction of ductus arteriosus flow (normally from the pulmonary trunk to the aorta) was reversed, and flowed from the aorta to the pulmonary trunk. This reversal of flow was probably of early onset in the fetus, the aorta receiving the total combined ventricular output, and produced a small ductus arteriosus with an acute inferior angle. It is extremely important not to rule out pulmonary atresia with an intact interventricular septum when aortography in the newborn shows a normal-sized ductus arteriosus with an obtuse inferior angle. Despite existing pulmonary atresia, these patients have neither a hypoplastic right ventricle nor discontinuity of the right ventricle with the pulmonary artery.

Preferential Atherosclerosis at the Aortic Junction of the Ligamentum Arteriosum: Clinical Significance and Pathological Correlation

Clinical experience with 5 patients who had complications of atherosclerosis within the aorta at the site of the obliterated ductus arteriosus suggested the occurrence of clinically significant preferential atherosclerosis at this location. To examine this hypothesis, the clinical findings in these patients (4 with saccular aneurysm and 1 with systemic emboli from an ulcerated plaque at this location) were correlated with postmortem examination of the aortic isthmus in 40 consecutive cadavers. The point of ductal closure was the area of most severe atheromatous involvement in 32 of the 40 cadavers, and 25 of the 40 specimens demonstrated ulcerated plaques at this location. Microscopical examination consistently demonstrated intimal irregularity or disruption and thinning of the aortic media in this area. These studies indicate that preferential atherosclerosis occurs at the aortic end of the obliterated ductus arteriosus and that these atherosclerotic changes can be a clinically significant development.