COARCTATION OF THE AORTA: THE COLLATERAL CIRCULATION

Society for Cardiovascular Magnetic Resonance/European Society of Cardiovascular Imaging/American Society of Echocardiography/Society for Pediatric Radiology/North American Society for Cardiovascular Imaging Guidelines for the use of cardiovascular magnetic resonance in pediatric congenital and acquired heart disease : Endorsed by The American Heart Association

Cardiovascular magnetic resonance (CMR) has been utilized in the management and care of pediatric patients for nearly 40 years. It has evolved to become an invaluable tool in the assessment of the littlest of hearts for diagnosis, pre-interventional management and follow-up care. Although mentioned in a number of consensus and guidelines documents, an up-to-date, large, stand-alone guidance work for the use of CMR in pediatric congenital 36 and acquired 35 heart disease endorsed by numerous Societies involved in the care of these children is lacking. This guidelines document outlines the use of CMR in this patient population for a significant number of heart lesions in this age group and although admittedly, is not an exhaustive treatment, it does deal with an expansive list of many common clinical issues encountered in daily practice.

Society for Cardiovascular Magnetic Resonance/European Society of Cardiovascular Imaging/American Society of Echocardiography/Society for Pediatric Radiology/North American Society for Cardiovascular Imaging Guidelines for the Use of Cardiac Magnetic Resonance in Pediatric Congenital and Acquired Heart Disease: Endorsed by The American Heart Association

Cardiovascular magnetic resonance has been utilized in the management and care of pediatric patients for nearly 40 years. It has evolved to become an invaluable tool in the assessment of the littlest of hearts for diagnosis, pre-interventional management and follow-up care. Although mentioned in a number of consensus and guidelines documents, an up-to-date, large, stand-alone guidance work for the use of cardiovascular magnetic resonance in pediatric congenital 36 and acquired 35 heart disease endorsed by numerous Societies involved in the care of these children is lacking. This guidelines document outlines the use of cardiovascular magnetic resonance in this patient population for a significant number of heart lesions in this age group and although admittedly, is not an exhaustive treatment, it does deal with an expansive list of many common clinical issues encountered in daily practice.

Chronic occlusion of the thoracic aorta: a novel cause of pleuropericardial effusions and pancytopenia

A 57-year-old man had presented with a 6-month history of worsening dyspnea, renal failure, hypertension, pancytopenia, and a continuous machinery murmur. Imaging studies revealed pleuropericardial effusions that recurred despite aspiration and suprarenal mid-thoracic aortic occlusion (AO) with extensive collateral vessels to the chest wall, rectus sheath, and diaphragm. A right axillofemoral bypass transformed his clinical course. The murmurs, renal failure, pleuropericardial drainage, and pancytopenia resolved, and his hypertension had markedly improved. The association of chronic AO with pleuropericardial effusions without peripheral edema or ascites was most likely due to increased supradiaphragmatic interstitial pressure, and the bone marrow hypoperfusion likely explains the pancytopenia. In addition to posing diagnostic challenges, chronic AO reveals unique insights into the pathogenesis of pleuropericardial effusions and pancytopenia.

Perioperative Anaesthetic Management for Laparoscopic Gastrectomy in a Patient with Coarctation of Aorta

Coarctation of the aorta (CoA) is a congenital condition, usually diagnosed and corrected early in life. Long-term survival with untreated coarctation is uncommon and is associated with high mortality rates in the fifth decade. A patient with CoA may present with problems while undergoing cardiac or non-cardiac surgical procedures which could pose considerable challenges in their anaesthetic management. Hence, the choice of anaesthetic technique plays an important role in determining the perioperative course and postoperative outcome in patients with CoA. This report discusses a case of middle-age man, recently diagnosed with CoA while undergoing a preanaesthetic assessment prior to the surgery for gastric adenocarcinoma involving proximal gastro-oesophageal junction. It highlights the successful anaesthetic management of CoA scheduled for laparoscopic-assisted gastrectomy for gastric adenocarcinoma. Perioperative management goals of the patient included general anaesthesia, epidural analgesia to avoid pain-associated adverse effects and efficient control of blood pressure distal to coarctation to limit the risk of intraoperative morbidity. It also demonstrates a major impact on anaesthesiologists who serve the most important role in managing such patients undergoing surgery with ‘red flag’ features.

The effect of including increased arterial stiffness in the upper body when modelling Coarctation of the Aorta

Coarctation of the Aorta is a congenital narrowing of the aorta and diagnosis can be difficult. Treatments result in idiopathic sequelae including hypertension. Untreated patients are known to develop increased arterial stiffness in the upper body, which worsens with time. We present results from simulations with a one-dimensional mathematical model, about the effect of stiffness, stenting, surgery and coarctation severity on blood pressure, Pulsatility and Resistivity Index. One conclusion is that increased stiffness may explain both hypertension in treated patients and why diagnosis can be difficult.

Concomitant percutaneous treatment of aortic coarctation and associated intercostal aneurysms: pre-procedural recognition is key

Intercostal aneurysms are associated with aortic coarctation. Their aetiology is not well-understood but may be related to intrinsic vascular pathology and altered flow dynamics through the intercostal artery. We present the cases of two patients with coarctation and intercostal aneurysms. The aneurysms were recognised on pre-catheterisation imaging studies and were selectively occluded during the same procedure to treat the coarctation. There were no complications; both the patients have no residual coarctation at the most recent follow-up. Intercostal aneurysms associated with coarctation can have significant consequences including late rupture, paralysis, and even death. These aneurysms are common with an incidence of up to 40% with adult-diagnosed coarctation; one treatment plan is to treat both the coarctation and aneurysm during a single catheterisation. Pre-catheterisation CT or MRI may play a role in this strategy.

Factors influencing the diameter of human anterior and posterior intercostal arteries

At present, there have not been any detailed studies examining the size relationships of the intercostal arteries. This study was carried out to investigate the relationship between the vessel lumenal diameter of ipsilateral, paired anterior and posterior IC arteries, as well as with the length of the IC space supplied by each artery. Samples were collected from the second-sixth anterior and posterior IC arteries near their site of origin, and the lengths of the corresponding IC spaces were measured in 42 cadavers. Lumenal diameters of both the anterior and posterior IC arteries at consecutive IC space closely followed second degree polynomial regression models (R(2) = 0.9655, and R(2) = 0.9741, respectively), and reached maximum size at the fifth IC space, which was found to be the longest of the IC spaces. No direct relationship was observed between diameters of the paired anterior and posterior IC arteries, although there was a trend for the larger anterior IC arteries to be paired with the larger posterior IC arteries. The calculated rate of blood flow at each IC artery was approximately two-fold greater in males than in females. These results suggest that the length of the IC space, and hence the extent of the thoracic wall supplied, is a major factor in determining the diameter of both anterior and posterior IC arteries. Since COPD is such a prevalent disease, this study also examined its influence on the IC arteries, and found that the posterior IC arteries are significantly larger among afflicted subjects.

The variant associations of aortic isthmic coarctation

The term "coarctation" necessarily calls attention to a specific morphologic abnormality of the aortic isthmus. However, in this report, the author seeks to dispel the simplistic notion that coarctation is best characterized by isthmic obstruction, which is only 1 of an assemblage of abnormalities that include the proximal paracoarctation aorta, the distal paracoarctation aorta, the ascending aorta, the transverse aorta, the coronary arteries, the conduit arteries (radial, brachial, and carotid), the retinal vascular bed, dissecting aneurysms, cerebral aneurysms, vascular rings, systemic hypertension, and a decrease in left ventricular interpapillary muscle distance. Some of these abnormalities are secondary to the coarctation, such as collateral arteries and dissecting aneurysms. Others frequently or invariably coexist but are not secondary, such as bicuspid aortic valve and aneurysm of the circle of Willis. Still other abnormalities are seemingly contradictory, such as aneurysmal dilatation of the low-pressure distal paracoarctation aorta, while the high-pressure proximal segment does not dilate significantly. In conclusion, coarctation should be regarded as an assemblage of cardiovascular abnormalities rather than as isolated obstruction of the aortic isthmus.

Suppressed hindlimb perfusion in Rac2-/- and Nox2-/- mice does not result from impaired collateral growth

While tissue perfusion and angiogenesis subsequent to acute femoral artery occlusion are suppressed in NADPH oxidase 2 (Nox2)-null (Nox2(-/-)) mice, studies have not established the role of Nox2 in collateral artery enlargement. Rac2 is a small GTPase that binds Nox2 and activates Nox2-based NAD(P)H oxidase but, unlike Nox2, is primarily restricted to bone marrow-derived cells. In this study, we used Rac2-null (Rac2(-/-)) and Nox2(-/-) mice with a novel method of identifying primary hindlimb collaterals to investigate the hypothesis that collateral growth requires these molecules. When initial experiments performed with femoral ligation demonstrated similar perfusion and collateral growth in Rac2(-/-) and wild-type C57BL/6J (BL6) mice, subsequent experiments were performed with a more severe ischemia model, femoral artery excision. After femoral excision, tissue perfusion was suppressed in Rac2(-/-) mice relative to BL6 mice. Histological assessment of ischemic injury including necrotic and regenerated muscle fibers and lipid and collagen deposition demonstrated greater injury in Rac2(-/-) mice. The diameters of primary collaterals identified during Microfil injection with intravital microscopy were enlarged to a similar extent in BL6 and Rac2(-/-) mice. Intimal cells in collateral cross sections were increased in number in both strains and were CD31 positive and CD45 negative. Circulating leukocytes and CD11b(+) cells were increased more in Rac2(-/-) than BL6 animals. Experiments performed in Nox2(-/-) mice to verify that the unexpected results related to collateral growth were not unique to Rac2(-/-) mice gave equivalent results. The data demonstrate that, subsequent to acute femoral artery excision, perfusion recovery is impaired in Rac2(-/-) and Nox2(-/-) mice but that collateral luminal expansion and intimal cell recruitment/proliferation are normal. These novel results indicate that collateral luminal expansion and intimal cell recruitment/proliferation are not mediated by Rac2 and Nox2.

Prevention of paraplegia during thoracic aortic cross-clamping: importance of patent internal mammary arteries

PURPOSE

Unexplained anatomic and physiologic factors account for the unacceptably high rate of paraplegia/paresis after thoracoabdominal aortic reconstruction. We assessed the neurologic significance of patent internal mammary arteries (IMAs) in a novel rat model of aortic clamping in which the aortic origins of the intercostal arteries (ICAs) were occluded.

METHODS

Twenty anesthetized, intubated, and halothane-ventilated adult male rats had catheters placed in the carotid and femoral arteries. ICAs arising from the aorta were divided at their origins through a left thoracotomy. IMAs were either divided (IMA-OUT, n = 10) or left intact (IMA-IN, n = 10). Proximal and distal descending aortic clamps were placed for 7 minutes. A neurologic deficit score (NDS) was assigned at 1, 4, 18, 24, and 48 hours by use of an established scoring system.

RESULTS

The mean IMA-IN NDS was statistically better than the mean IMA-OUT NDS at 1, 4, 18, and 24 hours with p = 0.0005, 0.0014, 0.0098, and 0.0151, respectively. Moreover, the mortality rate in the IMA-OUT group was statistically greater than in the IMA-IN group (p = 0.0036).

CONCLUSION

In this model, patent IMAs prevent paraplegia when the ICAs are occluded at their aortic origin and the aorta is clamped for 7 minutes.

Angiography of the internal mammary artery

The anatomy and catheterization techniques of the internal mammary artery (i.m.a.) are described. The diagnostic criteria and importance of i.m.a. angiography in thymoma, lymphoma, carcinoma, parathyroid adenoma, diseases of the breast, and trauma are discussed. The role of i.m.a. catheterization for i.a. infusion therapy in lung carcinoma, mesothelioma and chest wall metastases of breast carcinoma and embolization of i.m.a. in bleeding following trauma or tumour ulceration are described. Transcatheter treatment of mediastinal parathyroid adenoma is also described.

SURGERY OF THE DESCENDING THORACIC AORTA

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UNILATERAL RIB-NOTCHING FROM THE COLLATERAL CIRCULATION AFTER DIVISION OF THE SUBCLAVIAN ARTERY

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The course and prognosis of coarctation of the aorta

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COARCTATION OF THE AORTA: II. CLINICAL FEATURES

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