Extensive but minimally symptomatic deep vein thrombosis in duplicated femoral veins

Duplicated femoral veins predispose to venous thrombosis, but patients may present with minimal/no symptoms. The required length of treatment is unclear, but periodic ultrasound surveillance may play a role in the absence of definitive treatment options.

An anatomical pathway for restoration of bladder neck closure by a midurethral sling, according to the integral theory

A firm pubourethral ligament (PUL) is required to prevent the reflex posterior pelvic muscle forces forcibly opening out the posterior urethral wall on effort. A weak or loose PUL elongates on effort and this allows the posterior pelvic muscles to stretch open the posterior urethral wall causing urine loss, "stress urinary incontinence." Such forcible opening out of the urethra exponentially reduces the urethral resistance to flow inversely by the fourth power of the radius (i.e., 16 times). For example, if the radius doubles in size, the bladder pressure required for urine to flow out decreases by a factor of 16, from say, 160 to 10 cm H₂ O. A midurethral sling reinforces PUL to prevent the urethra opening out, thereby restoring both the distal urethral and bladder neck closure mechanisms.

Recipient Vessel Selection in Head and Neck Reconstruction

Objective: Recipient vessel caliber may be the single most important variable for flow to free tissue transfer. We performed cadaveric dissection of the external carotid artery and its branches to analyze average diameter in order to determine an algorithm for recipient vessel selection in head and neck reconstruction. Methods: The external carotid artery and branches were exposed on 3 lightly embalmed male human cadavers, aged 82 to 85 years. Each vessel was dissected, and luminal diameters were recorded with calipers. Results: The proximal ECA had the greatest average diameter (4 ± 0.6 mm) and potential flow; followed by distal ECA (2.85 ± 0.4 mm) facial (2.0 ± 0.6 mm), lingual (1.65 ± 0.6 mm), superior thyroid (1 ± 0.3  mm), and superficial temporal (0.85 ± 0.4 mm). There was a trend towards size variation between sides of the same cadaver. Conclusion: The external carotid artery has the greatest internal diameter and potential blood flow. It should be considered, when feasible, especially for defects of the upper third of the head. For defects of the lower third, the facial artery and the lingual artery should be utilized before the smaller diameter superior thyroid artery. Vessel selection is more challenging in the setting of radiation therapy, complex trauma, and prior neck surgery. In these settings, it is useful to have knowledge of the vascular anatomy and an objective algorithm for recipient vessel selection.

Quantitative comparison of cerebral artery development in metatherians and monotremes with non-human eutherians

A quantitative comparison of the internal diameters of cerebral feeder arteries (internal carotid and vertebral) and the aorta in developing non-human eutherians, metatherians and monotremes has been made, with the aim of determining if there are differences in cerebral arterial flow between the three infraclasses of mammals such as might reflect differences in metabolism of the developing brain. There were no significant differences between eutherians and metatherians in the internal radius of the aorta or the thickness of the aortic wall, but aortic internal radius was significantly smaller in developing monotremes than therians at the < 10 mm body length range. Aortic thickness in the developing monotremes also rose at a slower rate relative to body length than in metatherians or eutherians. The sums of the internal calibres of the internal carotid and vertebral arteries were significantly lower in metatherians as a group and monotremes compared with non-human eutherians at body lengths up to 20 mm and in metatherians at > 20 mm body length. The internal calibre of the internal carotids relative to the sum of all cerebral feeder arteries was also significantly lower in monotremes at < 10 mm body length compared with eutherians. It was noted that dasyurids differed from other metatherians in several measures of cerebral arterial calibre and aortic internal calibre. The findings suggest that: (i) both aortic outflow and cerebral arterial inflow may be lower in developing monotremes than in therians, particularly at small body size (< 20 mm); (ii) cerebral inflow may be lower in some developing metatherians than non-human eutherians; and (iii) dasyurids have unusual features of cerebral arteries possibly related to the extreme immaturity and small size at which they are born. The findings have implications for nutritional sourcing of the developing brain in the three infraclasses of mammals.

Quantitative comparison of cerebral artery development in human embryos with other eutherians

The embryonic and early fetal human brain is known to undergo extraordinary expansion of its cellular population during embryonic and early fetal life, and is critically dependant on a steady supply of nutrients and oxygen for proper brain development. Quantitative analysis of the internal radius of the aorta and cerebral arteries in a range of eutherian mammals has been used to compare arterial flow to the developing human brain with that to the brains of non-human eutherians. Human embryos showed a much steeper rise of internal radius of the aorta with increasing body size than the embryos of non-human eutherians, but the thickness of the aorta rose at the same pace relative to body size in both humans and non-humans, suggesting that aortic pressure is similar in all eutherian embryos of a similar size. The sums of internal radii of both the internal carotids and vertebral arteries of human embryos raised to the fourth power were much lower at embryonic stages (less than 22 mm body length) than in non-human eutherians, were similar between humans and non-humans at 22-30 mm body length, and exceeded the non-humans at body lengths of more than 30 mm. The relative size of the internal calibre of the cerebral feeder arteries (internal carotid and vertebral) to the aorta did not change between embryonic and fetal sizes in either humans or non-humans. The findings suggest that the developing human brain may actually receive less blood flow at embryonic sizes (less than 22 mm body length) than do other mammalian embryos of a similar body size, but that internal carotid and vertebral flow is higher in human fetuses (body length greater than 30 mm) than in developing non-humans of the same body size. Increased flow to the developing human brain relative to non-humans is achieved by simultaneous increases in both aortic and cerebral feeder artery internal calibre.

Pressure injectors for radiologists: A review and what is new

Pressure Injectors are used routinely in diagnostic and interventional radiology. Advances in medical science and technology have made it is imperative for both diagnostic as well as interventional radiologists to have a thorough understanding of the various aspects of pressure injectors. Further, as many radiologists may not be fully conversant with injections into ports, central lines and PICCs, it is important to familiarize oneself with the same. It is also important to follow stringent operating protocols during the use of pressure injectors to prevent complications such as contrast extravastion, sepsis and air embolism. This article aims to update existing knowledge base in this respect.

Radius exponent in elastic and rigid arterial models optimized by the least energy principle

It was analyzed in normal physiological arteries whether the least energy principle would suffice to account for the radius exponent x. The mammalian arterial system was modeled as two types, the elastic or the rigid, to which Bernoulli's and Hagen-Poiseuille's equations were applied, respectively. We minimized the total energy function E, which was defined as the sum of kinetic, pressure, metabolic and thermal energies, and loss of each per unit time in a single artery transporting viscous incompressible blood. Assuming a scaling exponent α between the vessel radius (r) and length (l) to be 1.0, x resulted in 2.33 in the elastic model. The rigid model provided a continuously changing x from 2.33 to 3.0, which corresponded to Uylings' and Murray's theories, respectively, through a function combining Reynolds number with a proportional coefficient of the l - r relationship. These results were expanded to an asymmetric arterial fractal tree with the blood flow preservation rule. While x in the optimal elastic model accounted for around 2.3 in proximal systemic (r >1 mm) and whole pulmonary arteries (r ≥0.004 mm), optimal x in the rigid model explained 2.7 in elastic-muscular (0.1 < r ≤1 mm) and 3.0 in peripheral resistive systemic arteries (0.004 ≤ r ≤0.1 mm), in agreement with data obtained from angiographic, cast-morphometric, and in vivo experimental studies in the literature. The least energy principle on the total energy basis provides an alternate concept of optimality relating to mammalian arterial fractal dimensions under α = 1.0.