Morphology of aortic arch obstruction with patent ductus arteriosus

Thirty-one hearts with aortic arch obstruction and patent ductus arteriosus were examined with special reference to associated cardiac anomalies. Six presented with complete interruption of the aortic arch, four with atretic isthmus, twelve with coarctation, and three with tubular hypoplasia. Associated cardiac anomalies were divided into two main groups: (1) septal defect with left-to-right shunt, and (2) left ventricular inflow and/or outflow obstruction. A high incidence (9/19=47.4%) of ventriculo-infundibular malalignment type of ventricular septal defect with subaortic stenosis was observed. Associated cardiac lesions that reduce blood flow in the aortic arch during fetal life may be responsible for poor development of this structure.     

Rheumatoid involvement of the aortic arch

The clinical course of rheumatoid arthritis may be complicated by cardiac involvement. Indeed, postmortem studies suggest rheumatoid involvement in up to 50% of pericardial, 5% of myocardial, and 60% of valvular specimens. Yet, in our search of the literature, we found only a single case report describing aortic valve replacement for rheumatoid valvulitis. This discrepancy may be related to the paucity of symptoms in this sedentary group of patients. A complete cardiac evaluation of patients with rheumatoid arthritis is recommended to select those with significant valvular involvement for timely surgical intervention prior to the development of irreversible left ventricular dysfunction. Two patients who benefitted from aortic valve replacement for rheumatoid valvular disease are presented.     

Interrupted aortic arch: an epidemiologic study

BACKGROUND: Interruption of the aortic arch (IAA) is a rare but severe anomaly associated with major intracardiac defects and with multisystem noncardiac malformations, recently linked to chromosome deletion of 22q11.2. METHODS: The Baltimore-Washington Infant Study (1981-1989), a population-based epidemiologic study of cardiovascular malformations, evaluated 53 infants with IAA in comparison with 3,572 controls. Risk factors for the anatomic subtypes were evaluated in 14 cases of IAA type A and 32 cases of IAA type B, but no molecular genetic tests were available. The distribution of associated cardiac defects was similar for both types. RESULTS: DiGeorge syndrome (DGS) occurred more frequently in IAA type B. Case-control comparisons demonstrated that infants in both groups were growth retarded at birth. A family history of noncardiac defects occurred only in IAA type B cases and included relatives with cleft lip and/or cleft palate. Candidate risk factors were associated only in type B cases and differed for those with (n = 10) and for those without (n = 19) DGS: a family history of noncardiac defects (odds ratio [OR] = 7.2, 95% confidence interval [CI] = 1.5-39.2) and maternal use of aspirin during the critical period (OR = 4.8, 95% CI = 1.3-25.4) occurred with DGS, while previous stillbirth (OR = 9.4, 95% CI = 1.3-53.1), bleeding during pregnancy (OR = 3.7, 95% CI = 1.4-11.4), and maternal exposure to arts/crafts paints (OR = 4.8, 95% CI = 1.3-17.4) were associated in those without DGS. CONCLUSIONS: These findings confirm the heterogeneity of IAA and of the type B subtype. Risk factors specific for cases with DGS may open a window to further investigations of the etiology of IAA and of the associated molecular genetic abnormalities.     

Familial recurrence of nonsyndromic interrupted aortic arch and truncus arteriosus with atrioventricular canal

BACKGROUND: Multifactorial inheritance is probably involved in most cases of nonsyndromic conotruncal heart defects (CHDs), but Mendelian transmission is often suspected. RESULTS: We report on a family with recurrence of nonsyndromic CTHD in two double first cousins; i.e., two brothers married two sisters. One of the cousins (case 1) had interrupted aortic arch (IAA) type B, while the other one (case 2) had truncus arteriosus (TA) with atrioventricular canal defect (AVCD). CONCLUSIONS: Our family further supports monogenic inheritance of CTHDs. In addition, the presence of TA associated with AVCD in one of the patients confirms the higher occurrence of CTHD in families with complex TA. The absence of 22q11 microdeletion (del22q11) in our patients, as in several literature reports of familial CTHDs, supports the existence of genes different to those located on chromosome 22q11 which could be implicated in the pathogenesis of CTHDs.     

Respiration-dependent shift in the region of the aortic arch

The contents of the mediastinum take part in a different degree in its inspiratory longitudinal expansion: Heart, pulmonary root, and the bifurcation of the trachea--all of them connected with the diaphragm by pericardium or membrana bronchopericardiaca--move caudad proportional to the sinking of the diaphragm. Compared with the corona cordis the planum cardiacum moves further caudad according to its distance from the upper apertura thoracis. So the heart necessarily has to compensate for this difference by taking an upright position and by rotation to the right. The arcus aortae, however, fixed in the neck by its three main branches cannot perform such a proportional excursion. A significant distance of the left pulmonary root from the aortic arch is the result. At the same time a subaortal space, the 'spatium subaortale mediastini', unfolds into which a bulge of the pleura mediastinalis moves. This bulge is filled with tissue of the upper lobe of the left lung.     

Entry flow in a circular tube of aortic arch dimensions

Steady flow within a uniform circular curved tube formed by two 90-deg elbows was studied as a function of psi, the angle between the planes of curvature of the two elbows. Boundary layer separation was found at two locations. The sites of these separation zones were observed to be essentially independent of psi while the Reynolds number at which separation was first detected was found to decrease as psi increased. The relation between separation and the pathogenesis of atherosclerosis is discussed. Secondary flow pattern was found to depend on psi and in some instances on Reynolds number as well.     

The influence of aortic dimensions on calculated wall shear stress in the mouse aortic arch

In this paper, the influence of the aortic dimensions of an investigated mouse on its resulting wall shear stress (WSS) was studied. A numerical model of a mouse aortic arch was created based on a micro-CT scan of a vascular corrosion cast of an 8-week-old wild type mouse. This model was then rescaled to obtain five models with aortic root diameters corresponding to five different stages in the mouse life cycle varying from late fetal (0.7 mm) to old adult (1.5 mm). Consistent with literature, WSS values much higher than those normally encountered in humans were found. WSS was found to decrease rapidly in early life stages and to reach a plateau in adulthood, thus supporting a mediating role for WSS in arterial growth. Our results show that WSS values for mice should be interpreted very cautiously, and if possible an animal-specific geometry with animal-specific boundary conditions should be used.