Arterialization of the venous system of the brain

The possibility of reverse perfusion of the brain (in which arterial blood flows to brain tissues through venous vessels, and venous blood is drained by the arteries) was studied in acute and chronic experiments on dogs. Blood pressure in cerebral veins could reach 90--120 mm Hg, in Willisii arteries it was 5--35 mm Hg. Liquor pressure reached 20--35 mmHg. After temporary arterialization of the brain venous system (10, 30 and 60 min) the animals survived without impairment of the brain function and behaviour. In the future reverse perfusion of the brain (in which blood pressure in the arteries falls to the level of venous pressure) could be used as a means of urgent surgical intervention in cases of threatened or beginning intracranial arterial hemorrhage.     

Dorsalis pedis tendocutaneous delayed arterialized venous flap in hand reconstruction

We report two patients whose acute soft-tissue and tendon defects in the hand were treated with a dorsalis pedis tendocutaneous delayed arterialized venous flap between 1994 and 1997. The surviving surface area was 100 percent in both patients. The flap sizes were 10 x 10 cm and 6 x 6 cm. At 2 weeks postoperatively, active flexion and passive extension commenced, and progressive resistance exercises were performed for an additional 5 weeks. Flaps showed a similar color match and skin texture compared with the normal skin of the hand. Advantages of the tendocutaneous delayed arterialized venous flap are that a larger flap can be obtained than when using a pure venous flap or arterialized venous flap; the survival rate of the arterialized venous flap increases, which permits the use of a composite flap; the main artery of the donor site is preserved; thin, nonbulky tissue is used; and elevation is easy, without deep dissection. The disadvantages are the two-stage operation, donor-site scarring, and weak extension of the toes.     

The anatomy of the extended peroneal venous system

The fibula has deservedly become a workhorse flap for vascularized bone grafts. As with most flaps, much is known regarding idiosyncrasies of its arterial supply, and the corresponding venous system has generally been assumed to be comparable. Because this donor site has become increasingly versatile, a detailed anatomic study that would verify this latter assertion should be important. Therefore, venous mapping specifically of the peroneal venae comitantes was completed in 29 fresh lower limbs. In every specimen, paired venae comitantes of large caliber indeed paralleled the course of the peroneal artery. All were of quality satisfactory for microanastomoses, which should provide reassurance that preoperative evaluation of the peroneal venous system is not routinely indicated. However, anatomic variations proved to be the norm. The two venae comitantes did not necessarily coalesce into a single common peroneal vein [6 of 29 (21 percent)]. Usually, the lateral peroneal vein was the larger and continued proximally either alone (17 percent) or as the common peroneal vein (66 percent) to form the lateral tibioperoneal vena comitans. Thus, the venous pedicle of a fibula flap could be lengthened up to its confluence with the popliteal vein, a maneuver that potentially could obviate the need for a vein graft at least on the venous side. Although anomalies of the peroneal artery could preclude use of the fibula altogether, there appeared to be no such contraindications from a venous standpoint, despite the fact that the venous anatomy was unique in every individual. Some important similarities in patterns, though, do exist. For example, a common peroneal vein was formed by the juncture of the lateral peroneal vein and some combination of branches joining the lateral posterior tibial vein and medial peroneal vein in 63 percent of all limbs. Because exceptions are the rule, the choice of donor vein and venous pedicle length best remains an intraoperative decision dependent on the presenting anatomy.     

Character phylogeny of the primate forelimb superficial venous system.

The ontogeny and comparative anatomy of the forelimb superficial veins were investigated in humans, non-human primates and other mammals. Adult humans and the orangutan (Pongo) possess two autonomous forelimb veins, one on the lateral (preaxial) margin of the limb, the other on the medial (postaxial) margin. All other adult primates and mammals examined possess a lateral vein alone. In African apes (Pan and Gorilla) and in 24% of human forelimbs the lateral vein is short, being essentially confined to the antebrachial region, whereas in other mammals and in 76% of human limbs the lateral vein runs from the carpus to the clavicular region. In humans the medial vein develops before the lateral vein, whereas in the rabbit and the pig the medial vein is present in early embryos but is subsequently lost. We propose that in humans, and probably also in the orangutan, the possession of a medial vein is a neotenic retention of a primitive tetrapod condition. These animals, which retain their medial vein, are united by losing a late stage in their ontogeny. Other animals subsequently pass through a stage in which the medial vein is lost, but Pongo and Homo retain this vein to adulthood. The loss of an ontogenetic stage can arise independently, and the presence of a medial vein therefore affords only weak evidence for a close phylogenetic relationship between humans and the orangutan. The polymorphic lateral vein of humans may be a character state that is intermediate between the derived (short) lateral vein of the African apes and the primitive long lateral vein of other non-human primates and mammals.     

A net-like structure in the venous system of the late chick embryo

A net-like structure of unknown function found at the junction of the umbilical vein and the left hepatic vein of the 16-day chick embryo is described. The net consists of strands of mesenchyme tissue covered by an endothelial layer continuous with that of the blood vessels in which it is located. An unusual feature of the net is the presence, at certain points where the strands meet, of hollow spherical or ellipsoid bodies, the walls of which are formed from a layer of simple cuboidal epithelium arranged upon a well defined basal lamina. The cavity of these bodies appears to contain some non-cellular material but they have no obvious duct to their exterior. The embryological origin of the net and its possible functions are discussed.     

Calf venous compliance in multiple system atrophy

In multiple system atrophy (MSA), increased venous compliance with excessive venous pooling is assumed to be a major contributor to orthostatic hypotension (OH); however, venous compliance has never been assessed in MSA patients. We evaluated the severity and distribution of adrenergic, cardiovagal, and sudomotor failure in 11 patients with probable MSA, 14 age- and sex-matched control subjects, and 8 patients with Parkinson's disease (PD) but not OH. Calf venous compliance, venous filling, and capillary filtration were measured using calf plethysmography. The response to the directly acting alpha-adrenergic stimulation (10 mg midodrine) on calf venous compliance was additionally evaluated. Contrary to our hypothesis, pressure-volume curves in the legs of MSA patients were flatter than in PD patients (P < 0.05) or controls (P < 0.001); this indicated reduced calf venous compliance in MSA. The MSA group had reduced venous filling compared with control (P < 0.001) or PD subjects (P < 0.001) but had a normal capillary filtration rate (P = 0.73). Direct alpha-adrenergic stimulation resulted in a slight but significant reduction of calf venous compliance in controls (P = 0.001) and PD subjects (P < 0.001) but not in the MSA group. The compliance change in MSA significantly regressed with autonomic failure (composite autonomic severity scale, r(2) = 0.56) but not with parkinsonism (Unified MSA Rating Scale, r(2) = 0.12). Our data indicate that MSA patients with chronic OH have reduced, rather than increased, venous compliance in the lower leg. We postulate that chronic venous distension that is associated with OH results in structural remodeling of veins, leading to reduced compliance, a change which may protect patients against orthostatic stress.     

Outcomes of Middle Cardiac Vein Arterialization via Internal Mammary/Thoracic Artery Anastomosis

Objective

Cardiac vein arterialization is seldom applied for treating right coronary artery disease. This study aimed to improve outcomes of cardiac vein arterialization in a porcine model using intramammary artery anastomosis.

Methods

A chronic, stenotic coronary artery model was established in 12 of 14 Chinese experimental miniature pigs of either sex, which were randomly divided into equal control (n = 6) and experimental (n = 6) groups. In experimental animals, blood flow was reconstructed in the right coronary artery using intramammary artery. Arterialization involved dissection of right internal mammary artery from bifurcation to apex of thorax followed by end-to-side anastomosis of internal mammary artery and middle cardiac vein plus posterior descending branch of right coronary artery. Intraoperative heart rate was maintained at 110 beats/min. Graft flow assessment and echocardiography were performed when blood pressure and heart rate normalized.

Results

The experimental group had significantly higher mean endocardial and epicardial blood flow postoperatively than control group (mean endocardial blood flow: 0.37 vs. 0.14 ml/(g*min), p<0.001; mean epicardial blood flow: 0.29 vs. 0.22, p = 0.014). Transmural blood flow was also higher in experimental group than in control group (0.33 vs. 0.19, p<0.001); ejection fraction increased from 0.46% at baseline to 0.51% (p = 0.0038) at 6 hours postoperatively, and mean blood flow of internal mammary artery was 44.50, perfusion index 0.73 at postoperative 6 months, 43.33 and 0.80 at 3 months.

Conclusion

Successful cardiac vein arterialization via intramammary artery in a porcine model suggests that this may be a viable method for reconstructing blood flow in chronic, severe coronary artery disease.