Artery subclavian

Mice homozygous for an ETA receptor gene disruption show craniofacial malformations, such as cleft palate, micrognathia, microtia and microglossia. ETA (—/—) mice die shortly after birth due to respiratory failure. Mice with an ET-l-null mutation show the same cranciofacial malformations and, in addition, cardiovascular disorders (e.g. septal defects, abnormal cardial outflow tract, aortic arch and subclavian arteries). 

The developmental effects of 1,4-dichlorobenzene have been evaluated in New Zealand White rabbits (Hayes et al. 1985). Pregnant rabbits were exposed to 1,4-dichlorobenzene by inhalation at 800 ppm for 6 hours per day on Gd 6-18. At 300 ppm, there was a significant increase in the number of litters with resorptions and the percentages of resorbed implantations per litter however, this effect was not seen at 800 ppm and was thus probably not treatment-related. An increased incidence of retroesophageal right subclavian artery present in the offspring was noted it was not considered to constitute a teratogenic response to exposure to 1,4-dichlorobenzene, but was considered only a minor variation. Based on the NOAEL of 300 ppm, an acute-duration MRL of 0.8 ppm was calculated as described in the footnote to Table 2-1 and Appendix A (Hayes et al. 1985). 

Animal data include an inhalation study in rabbits that resulted in an increased incidence of retroesophageal right subclavian artery in the fetuses (Hayes et al. 1985), and an oral study in rats that resulted in an increased incidence of an extra rib (NTP 1987). The data were considered sufficient to derive an acute-duration inhalation MRL of 0.8 ppm, based on a NOAEL of 300 ppm for lack of developmental effects in rabbits. It would be useful to have additional information on the developmental effects of 1,4-dichlorobenzene by inhalation and oral exposure in relation to maternal toxicity. There are currently no data available for the dermal route. Information on the developmental effects of dermal exposures would be useful if dermal absorption and systemic distribution of 1,4-dichlorobenzene could be demonstrated in toxicokinetic studies. 

Currently available devices are able to provide left ventricular support for a short duration only. Development of percutaneously or minimally invasive long-term support devices is also underway. At least three such devices are undergoing preclinical evaluation. The Synergy device (CircuLite, Inc., Hackensack, NJ) is being developed as a pocket circulatory assist (PAC) device that would sit in a subcuatenous pocket over the chest wall and use a micro-pump with cannulas in the subclavian artery and vein to withdraw blood from the left atrium through a transseptal approach and deliver it to the subclavian artery. The device is connected to a power... 

K9 18 146 2 11.1 2 1.4 1 Aortic arch fused 2 Malpositoned subclavian artery, small lungs, malformed kidney, marked dilated ureters... 

Second level of thoracic vessels—aortic arch arteries, common carotid and subclavian arteries, and innominate/brachiocephalic artery. 

Rijiht cproEid prtery Rigfu subdnvinn artery Left carotid artcr> Incminale artery Left subclavian artery Aortic arch... 

For the minipig (Fig. 11), the brachiocephalic trunk arises from the aortic arch and divides into the right subclavian and the bicarotid trunk (7). The bicarotid trunk then divides into the left and right carotid arteries. The left subclavian artery arises further downstream directly from the aortic arch. 

Left carotid artery Right carotid artery Hicarotid trunk Right subclavian artery... 

In 2005, scientists discovered the cause of Otzi s death. A few years earlier, in 2001, Paul Gostner wheeled an X-ray machine to Otzi s chamber in the South Tyrol Museum. Gostner, who works at the Central Hospital in Bolzano, Italy, discovered a stone arrowhead embedded in the back of Iceman s left shoulder. Earlier X-ray scans had missed the small object. The arrow shaft was not in Otzi s body, nor had it been found nearby. The fatality of the wound became evident in 2005, when Central Hospital acquired an X-ray machine with higher resolution. Gostner and other staff members of the hospital brought Otzi in for a scan—it was a rush job, otherwise Otzi s body would quickly decompose. They discovered that the arrowhead had gashed a large and important artery, the subclavian artery, which carries blood to the arm. Such a serious injury would have caused Otzi to bleed to death in minutes. 

In severe occlusive disease of the subclavian artery (SCA) blood supply of the arm is mainly provided by reversed flow through the vertebral artery (VA) arising behind the obstruction. The so-called subclavian-steal syndrome consists of ischemic symptoms in the arm, especially after exercise, such as pain or numbness or coolness (Reivich et al. 1961). Consequently a diminished or delayed pulse in the radial artery or decreased blood pressure on the side of SCA stenosis can be palpated. Rarely neurological symptoms such as spells of dizziness may be brought about by exercise ofthe arm. Even more rare are ischemic brainstem strokes in subclavian-steal syndrome (Bornstein and Norris 1986). 

Fig. 5.5a,b. Image postprocessing subtraction of pre- from post-contrast high resolution CE-MRA improves signal suppression from stationary tissue. Notice a mild blurring (smoothing) of the edges of the carotid arch and the proximal subclavian arteries, due to respiration and pulsations... 

Fig.5.7a-d. Time resolved sequential MRA. On high resolution CE-MRA (a), the left vertebral and left subclavian arteries are not fully enhanced. Selected images from a time-resolving sequence (b-d) with one frame per second demonstrate top-down contrast filling of the left vertebral artery and delayed enhancement of the left subclavian artery. Note low spatial resolution of sequential images... 

The truncus brachiocephalicus and the left CCA show a combined origin from the aortic arch in approximately 25% of cases. The left vertebral artery rarely arises directly from the arch proximal to the subclavian artery. Infrequently an aberrant right subclavian artery leaves the aorta distal to the left subclavian artery and crosses the mediastinum dorsal to the esophagus and is then called the arte-ria lusoria (Fig. 5.10). Elongations and ectasias of the aortic arch and supraaortal vessels, which can impair the imaging quality of the vessels, are often seen in elderly patients. 

Muscular branches of the vertebral artery in the neck. At positions distal to a vertebral obstruction, these muscular branches may receive blood retrogradely from occipital and ascending pharyngeal branches of the external carotid artery, or from the deep and ascending cervical arteries. In addition, anastomoses can develop between branches of the subclavian artery and external carotid artery when the common carotid artery is obstructed. 

Pathological, angiographic and ultrasonic studies show that the most common extracranial sites for atheroma are the aortic arch, the proximal subclavian arteries, the carotid... 

The subclavian artery can be damaged by a fractured clavicle or a cervical rib, with later embolization up the vertebral arteries or even up the right common carotid artery (Prior et al. 1979). 

Subclavian steal is caused by retrograde flow in the vertebral artery. It is a common angiographic or ultrasound finding when there is stenosis or occlusion of the subclavian artery proximal to the vertebral artery origin, particularly on the left, or of the innominate artery. When the ipsilateral arm is exercised, the increased blood flow to meet the metabolic demand may be enough to steal more blood down the vertebral artery, away from the brainstem into the axillary artery. If there is poor collateral blood flow to the brainstem, then symptoms may occur, but this is very rare. The subclavian disease is almost always severe enough to be detectable by unequal radial pulses and blood pressures, and often there is a supraclavicular bruit (Cho et al. 2007). 

Wyeth JA (1878). Prize essay essays upon the surgical anatomy and history of the common, external and internal carotid arteries and the surgical anatomy of the innominate and subclavian arteries. Appendix to Transactions of the American Medical Association (AMA) Philadelphia 29 1-245 Yadav JS, Roubin GS, King P et al. (1996). Angioplasty and stenting for restenosis after carotid endarterectomy. Initial experience. Stroke 27 2075-2079... 

---