Descending aorta

They also seeded autologous vSMC and ECs obtained from ovine carotid arteries to study autologous tissue-engineering blood vessels in the descending aorta of juvenile sheep. They found that after three months implantation, grafts were fully patent, without dilatation, occlusion, or intimal thickening. A continuous luminal EC layer was formed. However, after six months ... 

One of the last developed version of this system (Neotrend) was developed to monitor blood gases continuously and directly in critically-ill premature babies. The system is equipped with a tiny optical fibre catheter (0.5 mm in diameter) which is inserted into the infant s descending aorta by means of an umbelical artery catheter. A sketch of the probe is shown in Figure 4. 

Finally, at the Texas Heart Institute, we are developing a concept device that will consist of a catheter deployed micropump in the descending aorta and fixated with metallic struts to the aortic wall. It is designed to accelerate blood flow in the descending aorta to unload the heart. Its power will be supplied through a transarterial power cable to an outside power source. Though still in the conceptual phase only, it may be truly implantable in the cath lab without surgery. 

The ductus arteriosus joins the pulmonary trunk to the descending aorta. 

A later paper presented the results of a study of the mechanism of the sympathomimetic cardiovascular actions of I.H Cats and dogs anesthetized with allobarbital-urethane were used for measurements of pressure near the bifurcation of the descending aorta and of blood flow with electromagnetic probes. Intravenous Injection of I at 20 mg/kg was found to produce an immediate, sharp increase in blood pressure lasting for about 25 s and followed after a lag of about 6 s by an increase in blood flow. A slow drift downward of the peak systolic pressure followed. Repetition of the dose of I after an hour yielded responses similar to those after the first dose, but... 

In addition, the metabolic effects of insulin ultimately increase fetal oxygen consumption. The circulation of the fetus is unique specifically, because blood in the fetal descending aorta contains a portion of venous return after tissue perfusion, the increased rate of consumption of oxygen by fetal tissues decreases the arterial oxygen concentration of the fetus. The fetal tissues supplied by this circulation (which include most of the mass of the fetus) are then at risk for inadequate tissue oxygenation. 

Fig. 7. Schematic diagram of the canine femoral artery copper coil model of thrombolysis. A thrombogenic copper coil is advanced to either femoral artery via the left carotid artery. By virtue of the favorable anatomical angles of attachment, a hollow polyurethane catheter advanced down the left carotid artery nearly always enters the descending aorta, and with further advancement, into either femoral artery without fluoroscopic guidance. A flexible, Teflon-coated guidewire is then inserted through the hollow catheter and the latter is removed. A copper coil is then slipped over the guidewire and advanced to the femoral artery (see inset). Femoral artery flow velocity is measured directly and continuously with a Doppler flow probe placed just proximal to the thrombogenic coil and distal to a prominent sidebranch, which is left patent to dissipate any dead space between the coil and the next proximal sidebranch. Femoral artery blood flow declines progressively to total occlusion over the next 10-12 mm after coil insertion.

Fig. 11 Left lateral oblique images of rabbits with experimental atherosclerotic lesions induced in the descending aorta imaged with In-111 labeled murine-human chimeric Z2D3 F(ab )2 (A and C) and In-111 labeled human IgG F(ab )2 (B and D). The in vivo gamma images are shown in A and B (k = kidney, U = urinary bladder activity, solid thin arrows = atherosclerotic lesions, and open larger arrow = spinal activity), and the ex vivo images of the excised aortas from the aortic arch to the femoral bifurcation are shown in C and D.

Fig. 12 Immunoperoxidase staining of frozen sections of atherosclerotic rabbit descending aorta (A) and normal rabbit aorta (B).

Cut the descending aorta and collect 5 mL of blood from the cavity. 

Intra-aortic balloon piunps A balloon catheter inserted in the descending aorta and alternately inflated and deflated timed to the EKG in order to assist the ventricular pumping. 

In addition to intimal thickening, the arterial wall properties also change with age. Most measurements suggest that arterial elastic modulus increases with age (hardening of the arteries) however, in some cases arteries to become more compliant (inverse of elasticity) [Learoyd and Taylor, 1966]. Local weakening of the wall may also occur, particularly in the descending aorta, giving rise to an aneurysm, which, if ruptures, can cause sudden death. 

A study conducted by the same authors (Scliaus el al., 1955) on 100 samples of the thoracic descending aorta obtained from subjects ranging in age between 1 month and 83 years showed a definite decrease (Fig. 3) in the total riboflavin concentration of this tissue with age (r = —0.39 t = 4.20). 

Site Ascending aorta Descending aorta Abdominal Femoral aorta artery Carotid artery Arteriole Capillary Venule Vena cava, inferior Pulmonary artery, main... 

Tao Bolus tracking in the descending aorta, Tpa bolus tracking in the pulmonary trunk ... 

Fig. 23.2. Combination CTA of the thoracic and abdominal aorta with a single contrast application. Le coronary MPR, right sagittal MPR. The white arrowheads mark the change between the ECG-gated acquisition of the thoracic aorta and the standard acquisition of the abdominal aorta There is a dissection Stanford type B in the descending aorta the entry is distal of the left subclavian artery, the reentry is on a level with the diaphragm (arrows)...

Thoracic aortic aneurysm (TAA) is defined as a persisting dilatation of the ascending aorta larger than 4 cm and of the descending aorta larger than 3 cm (Issel-... 

The challenge for spinal artery CTA is to provide sufficient arterial enhancement but to scan before arrival of contrast medium in the venous system. An ROI of the bolus tracking system placed in the ascending aorta might be affected by inflow artifacts of the SVC and may result in a mistimed early scan. Therefore, placement of the ROI in the aortic arch or descending aorta is recommended. In the presence of aortic dissection, caution should be taken that the ROI is not too big or positioned in the false lumen or across the dissection membrane, respectively. In these cases, manual start of the scan should be considered. The Hounsfield unit threshold should be around 100 HU above baseline. Scan start is usually delayed by time for table movement (<3 s), which is usually right above the origin of the vertebral arteries. An additional scan delay of 3 s is recommended for scanners with equal to or more than 16 rows and rotation time equal or less than 0.4 s. Hounsfield unit values of attenuated blood in the thoracic aorta should never be lower than within the pulmonary trunk. 

Access to the aortic valve is achieved either transfemoraUy, via apical entry through the left ventricle (LV), or direcdy through incision into the descending aorta. The latter two techniques require a minithoracotomy for access, but provide more direct control of the delivery tool. Stents are either made from a shape-memory alloy or use an inflatable balloon for deployment. Since their inception, a wide variety of devices are currently in the market (Figure 4.14). 

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