Management of subclavian and axillary artery injuries: spanning the range of current therapy

Injuries of the subclavian and proximal axillary arteries are potentially devastating but account for a minority of vascular injuries presenting to trauma centers in the United States. We have reviewed our recent experience with management of subclavian and axillary artery injuries in a state-designated level 1 academic trauma center and report four cases that illustrate the typical arterial injury patterns and the entire therapeutic armamentarium in its current iteration. Subclavian and proximal axillary artery injuries present as interesting surgical problems. A high index of suspicion for vascular injuries should be maintained given the mechanism and proximity to major vasculature. Consideration should always be given to the least invasive treatment options in stable patients. Awareness of multiple therapeutic modalities and indications for each should be an integral part of every surgeon's armamentarium. As with all vascular intervention, eventual failure is the rule rather than the exception; therefore, plans for longitudinal surveillance should be made independent of the technique used to treat the injury.

Inhibition of arterial cells proliferation in vivo in injured arteries by hyaluronan fragments

It has been demonstrated previously that administration of high levels of high molecular mass hyaluronan (hyaluronic acid, HA) to rats was able to reduce in a significant way neointima formation in the injured arteries. In the present study, our aim was to verify whether small forms of HA (4-16 saccharides) are still able to reduce the proliferative response of ASMC to aortic injury. Treated rats received a total of 8 injections of a fixed dose of HA fragments (27 mg/kg rat contained in a volume of 550 microl). Two injections were given on the day of balloon catheter injury (BCI): one, intravenous, 10 min before BCI and one, subcutaneous, immediately after the BCI. The others injections (subcutaneous) were at 2, 4, 6, 8, 10 and 12 days after BCI. Control rats received an equivalent volume of the dissolving buffer containing only hyaluronidase, which has been destroyed before injection to rats. Neointima formation was analysed 14 days after the BCI. Intima-media wet weight and DNA content were significantly reduced in rats receiving HA fragments in comparison to controls (2P=0.01 for wet weight and 0.03 for DNA). This finding was confirmed by the histomorphometric study which showed that both neointima area and the ratio neointima/neointima+media were significantly decreased in treated rats (2P=0.03 for intima area and 0.049 for the ratio). Our data showed thus and for the first time that administration of HA fragments with a very low molecular mass (4-16 saccharides) reduces the proliferative reaction of aorta to injury in vivo. In conclusion, HA fragments, which are components with an excellent safety profile, may offer hope for the prevention of restenosis after angioplasty.

Urokinase lysis for acute left subclavian artery thrombosis after placement of infusion catheter: report of two cases

We present two cases of acute subclavian and/or axillary arterial occlusion after transaxillary catheterization with an implantable port for hepatic arterial infusion chemotherapy. They were successfully treated with thrombolytic therapy using intraarterial administration of urokinase without removal of the infusion catheter system. We consider that this treatment is suitable for managing acute thrombosis of the conduit artery after catheterization for hepatic arterial infusion chemotherapy.

Sublingual nitroglycerin delays arterial wave reflections despite increased aortic "stiffness" in patients with hypertension: a Doppler echocardiography study

Venodilatation with consequent reduction in left ventricular filling and end-diastolic wall stress is an important mechanism for the beneficial effects of nitroglycerin in ischemic heart disease and in left ventricular failure. The effects of sublingual nitroglycerin on arterial pulsatile hemodynamics are less well defined. Doppler echocardiography and the calibrated subclavian artery pulse tracing were used to assess hemodynamics in subjects with sustained arterial hypertension (n = 25) before and 5 to 10 minutes after sublingual deposition of 0.5 mg glyceryl trinitrate. Aortic characteristic impedance was calculated by averaging the modulus of the input impedance (ratio of pressure to flow) at high frequencies and by calculating the ratio of pressure and flow increments during upstroke. The pressure wave was split into forward and backward components, and the reflection coefficient (the ratio of backward to forward pressures) was calculated. Parameters of the arterial bed were estimated by using 2- and 3-element Windkessel models. Nitroglycerin delayed the return of arterial wave reflections by 17% (P =.02) and increased aortic characteristic impedance by 20% (P =. 01), but it did not influence total arterial compliance. Mean arterial pressure decreased 7% (P =.0001), but pulse pressure did not change. Stroke volume and the acceleration time of aortic root flow decreased by 13% (P =.0001) and 8% (P =.01), respectively. Cardiac output decreased 7% (P =.01), despite an increase in heart rate of 10% (P =.0001). Peripheral resistance tended to decrease (4%, P =.06). Thus, in subjects with sustained hypertension, sublingual nitroglycerin dilates peripheral, predominantly muscular arteries with a subsequent delayed return of reflected pressure waves. Reflex activation of the sympathetic nervous system with consequent increased acceleration of left ventricular ejection seems to counteract the effect of reduced mean arterial pressure (distending pressure) with respect to the "stiffness" of the aorta.

A rapid, quantitative method for measuring leukocyte adhesion to normal and balloon-injured arteries in vitro

Many of the currently available techniques for quantifying leukocyte adhesion require monolayers of cells and are therefore unsuitable for use in ex vivo arterial tissue. Here we describe a rapid method to measure adhesion of leukocytes to intact artery strips and to determine the effect of artery injury on adhesiveness of leukocytes with and without activation. Leukocytes were isolated from rabbit blood, labelled with 51Cr, and added to the luminal face of the left and right subclavian arteries derived from the same animal. In some experiments the endothelium was removed before addition of leukocytes and in another series of experiments the artery was injured by inflating a balloon catheter within the lumen in vitro before leukocyte addition. After washing, the adhesion of labelled leukocytes was quantified by gamma counting. To determine localization of the leukocytes, some arteries were fixed in situ and examined microscopically, with confirmation of leukocyte identification by enzyme cytochemistry. The adhesion of leukocytes increased progressively during 60 min and was inhibited by reducing the temperature to 4 degrees C. Adhesion was increased by the nitric oxide synthase inhibitor L-NAME. Stretching the artery wall in vitro using a balloon catheter increased leukocyte adhesion within 1 h after injury. In contrast, this did not occur following simple arterial denudation. Histological examination of stained en face preparations and transverse sections of the subclavian arteries revealed loosely adherent granulocytic leukocytes on the endothelial surface. This technique is straightforward and allows accurate and rapid measurement of autologous leukocyte adhesion to normal and pathologically altered arteries ex vivo.

Correlation of leukocyte adhesiveness, adhesion molecule expression and leukocyte-induced contraction following balloon angioplasty

1. The aim of this study was to examine the changes in leukocyte adhesion and leukocyte-induced contraction in balloon-injured rabbit subclavian artery and to correlate these changes with vessel morphology and expression of adhesion molecules on the injured arteries. 2. Rabbits were anaesthetized and their left subclavian arteries were injured by balloon inflation and withdrawal followed by sacrifice at 2, 24, 48 h or 8 days after injury. The left and right subclavian arteries were removed and leukocytes were isolated from autologous rabbit blood. Leukocyte-induced contraction was measured in 5-HT precontracted artery rings and leukocyte adhesion was measured using (51)Cr-labelled leukocytes. Immunocytochemistry using paraffin-embedded tissue was employed to detect changes in the expression of adhesion molecules on injured arteries. 3. Autologous leukocytes caused a contraction of rabbit subclavian artery rings, which was prevented by L-NAME (10(-3) M). Balloon-induced injury abolished the contractile response to leukocytes, which correlated with loss of carbachol-induced relaxation 4. Balloon injury markedly enhanced the adhesiveness of the subclavian artery for leukocytes, most notably at 24 and 48 h after injury (1.7 and 1.8 fold respectively). Increased leukocyte adhesion at these two time points correlated with an upregulation of E-selectin, P-selectin and VCAM-1 expression on the remaining endothelium of the injured artery. 5. Vessel morphology revealed that balloon inflation had induced an infiltration of inflammatory cells into the vessel wall, the greatest increase being seen at 24 h after injury. 6. It is concluded that an increase in the expression of E-selectin, P-selectin and VCAM-1 following balloon-induced injury leads to enhanced leukocyte adhesion and migration into the injured vessel.

Benzofuranyl ureas with potent cardiovascular teratogenicity in rats

Studies of embryo-fetal development in rats were conducted with two 5-lipoxygenase inhibitors. SB-202235 (1,000 mg/kg/day) or SB-210661 (50, 100, or 500 mg/kg/day) was administered orally by gavage to female rats on days 6-17 postcoitus (pc) or days 7-16 pc. SB-202235 (1,000 mg/kg/day) and SB-210661 (100 mg/kg/day) reduced maternal body weight gain for the treatment period by 16% and 21%, respectively, relative to controls. SB-202235 (1,000 mg/kg/day) or SB-210661 (50 or 100 mg/kg/day), did not affect numbers of resorptions, dead or live fetuses/litter, but 500 mg/kg/day of SB-210661 caused 100% embryo lethality. SB-202235 (1,000 mg/kg/day) and SB-210661 (50 and 100 mg/kg/day) reduced fetal body weight by 15-30% and produced extensive cardiovascular malformations, as well as diaphragmatic hernias. SB-210661 also caused thymic abnormalities and cryptorchidism. Cardiovascular defects included abnormalities in aorticopulmonary septation, the aortic arch, pulmonary trunk, and ventricular septal defects are discussed relative to comparable human syndromes of cardiovascular malformation.

Photoplethysmographic assessment of pulse wave reflection: blunted response to endothelium-dependent beta2-adrenergic vasodilation in type II diabetes mellitus

OBJECTIVES

We sought to determine whether a simple index of pressure wave reflection may be derived from the digital volume pulse (DVP) and used to examine endothelium-dependent vasodilation in patients with type II diabetes mellitus.

BACKGROUND

The DVP exhibits a characteristic notch or inflection point that can be expressed as percent maximal DVP amplitude (IP(DVP)). Nitrates lower IP(DVP), possibly by reducing pressure wave reflection. Response of IP(DVP) to endothelium-dependent vasodilators may provide a measure of endothelial function.

METHODS

The DVP was recorded by photoplethysmography. Albuterol (salbutamol) and glyceryl trinitrate (GTN) were administered locally by brachial artery infusion or systemically. Aortic pulse wave transit time from the root of the subclavian artery to aortic bifurcation (T(Ao)) was measured by simultaneous Doppler velocimetry.

RESULTS

Brachial artery infusion of drugs producing a greater than threefold increase in forearm blood flow within the infused limb was without effect on IP(DVP), whereas systemic administration of albuterol and GTN produced dose-dependent reductions in IP(DVP). The time between the first and second peak of the DVP correlated with T(Ao) (r = 0.75, n = 20, p < 0.0001). The effects of albuterol but not GTN on IP(DVP) were attenuated by N(G)-monomethyl-L-arginine. The IP(DVP) response to albuterol (400 microg by inhalation) was blunted in patients with type II diabetes mellitus as compared with control subjects (fall 5.9 +/- 1.8% vs. 11.8 +/- 1.8%, n = 20, p < 0.02), but that to GTN (500 microg sublingually) was preserved (fall 18.3 +/- 1.2% vs. 18.6 +/- 1.9%, p = 0.88).

CONCLUSIONS

The IP(DVP) is influenced by pressure wave reflection. The effects of albuterol on IP(DVP) are mediated in part through the nitric oxide pathway and are impaired in patients with type II diabetes.

Vasorelaxant and antiaggregatory properties of the endothelium: a comparative study in normocholesterolaemic and hereditary and dietary hypercholesterolaemic rabbits

1. A comparison of the effects of dietary and genetically-induced hypercholesterolaemia on the vasodilator and antiaggregatory capacity of the endothelium was made in rabbit isolated subclavian artery rings. 2. Dietary-induced hypercholesterolaemia in NZW rabbits decreased the maximum relaxation to carbachol (0.01-10 microM) and calcimycin (0.01-0.1 microM) in vessel rings precontracted with 5-hydroxytryptamine (5-HT), 0.1 microM), when compared to responses observed in rings obtained from control normocholesterolaemic NZW rabbits. The relaxant responses to SIN-1 (3-(4-morpholinyl)-sydnonimine hydrochloride) were attenuated but were not significantly different from controls. In Froxfield genetically hypercholesterolaemic (FHH) rabbits, the maximum relaxations to carbachol, calcimycin and SIN-1 were all reduced significantly. 3. Neither genetic nor dietary-induced hypercholesterolaemia modified the contractile responses of vessel rings to either KCl (10-100 mM) or 5-HT (0.01-10 microM). 4. Endothelium-dependent inhibition of collagen-induced platelet aggregation in whole blood was demonstrated by stimulation of a vessel ring, incorporated into the blood sample, with carbachol (10 microM, final blood concentration). This effect was inhibited by NG-nitro-L-arginine (L-NOARG, 100 microM). SIN-1 (10 microM, final blood concentration) also decreased whole blood platelet aggregation, but only in the presence of an unstimulated vessel ring, and this was unaffected by L-NOARG. Superoxide dismutase (150 u ml-1) did not influence the inhibition of aggregation by either a carbachol-stimulated vessel ring or by SIN-1. 5. Carbachol-stimulated artery rings from FHH rabbits inhibited platelet aggregation to a similar extent to that seen with rings from control normocholesterolaemic rabbits. Rings from hypercholesterolaemic NZW rabbits, however, did not significantly inhibit platelet aggregation when stimulated with carbachol. SIN-1 inhibited platelet aggregation in the presence of rings from either group of hypercholesterolaemic rabbits. 6. Hypercholesterolaemia induced by dietary modification induces changes in endothelial function which are characteristically different from those seen in genetically hypercholesterolaemic rabbits. It appears that dietary-induced hypercholesterolaemia primarily decreases NO release from the endothelium, while in genetically-induced hypercholesterolaemic vessel rings NO is released but there is a decreased responsiveness of the vascular smooth muscle cells to NO. This may reflect differences in the age and severity of the atherosclerotic lesions in the two groups of rabbits.

Subcutaneous infusion of r-hirudin does not inhibit neointimal proliferation after angioplasty of the subclavian artery in cholesterol-fed rabbits

BACKGROUND

Thrombin, a potent stimulator of smooth muscle cell proliferation and inhibitor of endothelial cell growth, has been implicated as an important mediator of restenosis after angioplasty. Acute administration of the thrombin inhibitor r-hirudin reduced restenosis in animal models of angioplasty, possibly by inhibiting smooth muscle cell proliferation. Because thrombin-induced proliferation requires prolonged exposure to the agonist, it was hypothesized that a greater reduction in lesion size could be achieved by chronic administration of r-hirudin.

OBJECTIVE

To determine whether prolonged treatment with r-hirudin would reduce lesion size and improve vascular function in a rabbit model of neointimal proliferation.

METHODS

Male New Zealand white rabbits were fed a high-cholesterol diet for 4 weeks, after which they were subjected to balloon injury of the left subclavian artery. The rabbits were assigned to one of three groups: control (no drug); acute r-hirudin treatment (0.33 mg/kg intravenously plus 0.48 mg/kg per h subcutaneously for 24 h); or chronic r-hirudin treatment (0.33 mg/kg intravenously plus 0.6 mg/kg per h subcutaneously for 28 days). After surgery the rabbits were fed a normal diet and killed 30 days later. Left (angioplastied) and right (control) subclavian arteries were removed for morphological and functional analysis.

RESULTS

Angioplasty in control, untreated rabbits produced large neointimal lesions [15.0 +/- 1.8% of the area within the external elastic lamina (EEL)], comprised mainly of smooth muscle cells (34 +/- 16 cells/section) and lipid-rich macrophage or foam cells (118 +/- 51 cells/section). Acute r-hirudin treatment neither inhibited smooth muscle cell proliferation (35 +/- 12 cells/section) nor reduced neointimal lesion size (23.5 +/- 4.6% of the area within the EEL). Chronic r-hirudin treatment significantly increased the number of proliferating cells (55 +/- 15 cells/section, P < 0.05) and the size of the lesions (28.5 +/- 5.6% of the area within the EEL, P < 0.05). Further more, treatment with r-hirudin appeared to exacerbate, rather than improve, angioplasty-induced functional alterations.

CONCLUSIONS

Prolonged treatment with r-hirudin neither inhibits vascular smooth muscle cell proliferation in rabbits after angioplasty of the left subclavian artery nor reduces the size of neointimal lesions. Furthermore, treatment with r-hirudin might impair endothelial cell function after angioplasty. This suggests that prolonged thrombin inhibition using this r-hirudin regimen is not suitable as an antirestenotic intervention.

The role of vascular injury and hemodynamics in rat pulmonary artery remodeling

Vascular remodeling in adult human elastic pulmonary arteries is characterized by diffuse neointimal lesions containing smooth muscle cells expressing extracellular matrix genes. Recent studies suggest vascular injury is needed to initiate remodeling and that growth factor mediators participate in the repair response. However, because neointimal formation is only observed in patients with pulmonary artery blood pressures approaching systemic levels, it has been hypothesized that systemic-like hemodynamic conditions are also necessary. To test that hypothesis, subclavian-pulmonary artery anastomoses were created in Sprague-Dawley rats under three different experimental conditions: no accompanying injury, or after monocrotaline or balloon endarterectomy injury. Pulmonary vascular remodeling was not induced by the subclavian-pulmonary artery anastomosis alone. A non-neointimal pattern of remodeling after mild monocrotaline-induced injury was converted into a neointimal pattern in the presence of the anastomosis. Neointima was also observed after severe, balloon endarterectomy-induced injury even in the absence of anastomosis. Tropoelastin, type I procollagen and TGF-beta gene expression, and angiotensin converting enzyme immunoreactivity, was confined to the neointima resembling the pattern of gene expression and immunoreactivity in human hypertensive elastic pulmonary artery neointimal lesions. These observations introduce the concepts that the type of injury and the associated hemodynamic conditions can modify the elastic pulmonary artery response to injury.