Photodynamic therapy. Cytotoxicity of aluminum phthalocyanine on intimal hyperplasia

OBJECTIVE

To study the cytotoxic effect of photodynamic therapy (PDT) on myointimal hyperplasia (MIH) in 120 New Zealand white rabbits using the chromophore chloroaluminum phthalocyanine tetrasulfonate (APtS).

DESIGN

A common carotid artery (CCA) injury model was used to initiate MIH. Photodynamic therapy was administered 1 week after injury (inhibition arm) or 6 weeks after injury (treatment arm). The inhibition arm CCAs were harvested 6 weeks after therapy. The treatment arm CCAs were harvested 1 week or 6 weeks after therapy. Each evaluation included four subgroups (n = 10 each): control, drug only, laser only, and drug plus laser.

INTERVENTIONS

An established CCA balloon injury model was used. Photodynamic therapy was administered by exposing CCAs to continuous external laser irradiation 30 minutes after treatment with a 2.5-mg/kg intravenous dose of APtS (fluence = 25 J/cm2, lambda = 672 nm). The control and drug-only subgroups received sham reoperations without laser exposure.

MAIN OUTCOME MEASURES

Following harvest, the CCAs were evaluated for area of stenosis and cell density.

RESULTS

In the inhibition arm, no PDT effect was seen on intimal cell density or area stenosis. In the treatment arm, intimal cell density was markedly diminished (P < .05) in the rabbits in the drug-laser group that were killed 1 week but not 6 weeks after PDT compared with rabbits in the control, drug-only, and laser-only groups. Area stenosis was not significantly affected by PDT.

CONCLUSIONS

Marked acute cytotoxicity of PDT on MIH was verified in vivo in the treatment arm. No sustained benefit of PDT was seen in the inhibition or the treatment arms. Refinements in dosimetry will be necessary to achieve long-term benefit of PDT for MIH.

The evolution of multiple sclerosis lesions on serial MR

PURPOSE

To characterize temporal changes in signal intensity patterns of multiple sclerosis lesions on serial MR.

METHODS

T1-, T2-, proton density-, and contrast-enhanced T1-weighted MR was performed on five patients with relapsing-remitting multiple sclerosis at least 22 times in the course of 1 year.

RESULTS

Forty-three enhancing lesions and 1 new lesion that never showed enhancement were detected and followed for periods ranging from approximately 4 weeks to 1 year (total of 702 time points). At first detection the center of new lesions was brighter than the periphery (20 of 24 new lesions on proton density-weighted and 19 of 23 new lesions on contrast-enhanced images). On contrast-enhanced images, ring hyperintensity was predominant at time points later than 29 days. As lesions aged, a residual rim of "nonenhancing" hyperintensity often was noted on contrast-enhanced images. Some older lesions (> 1 year) showed similar appearance on unenhanced T1-weighted images. On proton density-weighted images ring hyperintensity was most frequent 2 to 4 months after lesion detection. The estimated average duration of gadopentetate dimeglumine enhancement was 1 to 2 months.

CONCLUSIONS

A lesion evolution pattern relevant to MR was inferred. We believe that specific information about the histopathologic evolution of a lesion may be extracted not only from contrast-enhanced but also from nonenhanced serial MR. Assessment of drugs targeting specific phases of lesion evolution could benefit from quantitative pattern analysis of routine MR images.

Correlation of striatal dopamine release and peripheral hypertension after transient ischemia in gerbils

PURPOSE

Intracranial norepinephrine release has been associated with post-carotid endarterectomy hypertension in human beings. To study this phenomenon under more controlled conditions, we studied the relationship of cerebral catecholamines and blood pressure in gerbils, whose cerebral circulation is similar to that in human beings.

METHODS

Twelve anesthetized gerbils underwent iliac artery blood pressure monitoring and in vivo electrochemistry catecholamine monitoring with use of catecholamine-specific electrodes placed stereotactically into the cerebral striatum. Six gerbils underwent 10 minutes of bilateral carotid artery occlusion (ischemic), whereas six underwent carotid artery dissection without occlusion (control).

RESULTS

The control group demonstrated a continuous gradual decline in blood pressure and striatal catecholamine during the 150-minute observation period. In contrast the ischemic gerbils demonstrated a sharp catecholamine rise during ischemia, a marked catecholamine drop shortly after carotid artery unclamping, and then a secondary larger catecholamine release that peaks in 60 minutes and gradually returns to baseline in 120 minutes. The blood pressure closely followed the catecholamine levels, with a sharp 20 mm Hg rise in blood pressure above baseline during carotid artery occlusion, followed by a dramatic 10 mm Hg drop below baseline after carotid artery unclamping and then a gradual rise of the blood pressure 25 mm Hg above baseline, which peaks in 80 minutes, with a gradual decline to the same blood pressure as in the control subjects 120 minutes after ischemia.

CONCLUSION

We conclude that striatal catecholamine release correlates with peripheral blood pressure during transient cerebral ischemia and reperfusion. This phenomenon may explain the mechanism of post-carotid endarterectomy hypertension in human beings, and this gerbil model can be used to study its prevention and treatment.

Endovascular femoropopliteal bypass: a cadaveric study

OBJECTIVE

Patency rates of standard femoropopliteal bypass in infra-inguinal occlusive disease have yet to be matched by minimally invasive percutaneous procedures. We report a feasibility study of a less invasive endovascular femoropopliteal bypass technique.

METHODS

(1) groin exposure of femoral artery, (2) guidewire passage and mechanical dilatation of superficial femoral artery (SFA), (3) expandable helical cutter endarterectomy of SFA, (4) transluminal placement of PTFE graft, (5) graft balloon dilatation to shape and set distal interface and (6) end-to-end anastomosis of proximal graft to femoral artery. Development and testing was undertaken in 48 limbs of 26 fresh human cadavers. Limbs with no demonstrable SFA disease were excluded. Seventeen limbs had mild, diffuse disease. Three limbs had a single, short, tight stenosis. Seventeen limbs had multiple, high grade stenotic lesions 12-40 cm long (mean 24 cm). Eleven limbs had occlusive lesions, 8-38 cm long (mean 24 cm).

RESULTS

We successfully completed the procedure in 39 (81%) limbs. We failed to complete the procedure in nine limbs; four from failed guidewire passage, four from vessel avulsion, and one from graft deployment failure. Histology confirmed endarterectomy cleavage in the standard plane. Angiography and explants demonstrated a patent graft and popliteal artery, and smooth distal graft/arterial interface with no obvious defects in 24 (62%) cases. Defects included combinations of: contrast extravasation/reflux, graft malpositioned/incorrectly sized, distal graft fold, and distal intimal flap.

CONCLUSION

Endovascular femoropopliteal bypass is feasible and warrants further studies for possible clinical application.

Endovascular femoropopliteal bypass: early human cadaver and animal studies

We report herein a feasibility study of a minimally invasive endovascular femoropopliteal bypass procedure. The steps include the following: (1) a small groin incision to expose the femoral artery, (2) guidewire passage and mechanical dilatation of the diseased superficial femoral artery, (3) semiclosed endarterectomy of the superficial femoral artery using an expandable metal endarterectomy catheter that engages atheroma, (4) placement of a 6 mm thin-walled PTFE graft, (5) balloon dilatation of the graft to press the graft flat against the arterial wall, and (6) a standard end-to-end anastomosis of the proximal graft to the femoral artery. This technique was tested in 13 limbs from eight fresh (stored 1 to 5 days at 4 degrees C) human cadavers (seven females and one male). Five limbs had stenotic superficial femoral artery lesions, 1 to 15 cm (mean 7.6 cm). Four limbs had occlusive lesions, 9 to 38 cm long (mean 26.8 cm). Four limbs had no disease. We successfully completed the procedure in 10 of 13 limbs. Completion arteriography showed a widely patent graft and a popliteal artery with a smooth distal graft/arterial interface in 9 of 10 limbs; one had a distal graft fold due to a size mismatch. Histologic studies of the superficial femoral artery revealed intima, atheromatous plaque, and media. We failed to complete our procedure in three limbs: two because of inadequate instruments and one because of perforation of the artery. We also performed the same procedure unilaterally in six dogs, except that no endarterectomy was performed.(ABSTRACT TRUNCATED AT 250 WORDS)

Longitudinal MRI in multiple sclerosis: correlation between disability and lesion burden

We followed 18 multiple sclerosis patients clinically and with repeated brain MRIs with and without gadolinium for over 1 year. Clinical evaluations included scoring on the Kurtzke Expanded Disability Status Scale (EDSS) and the Ambulation Index (AI) scale. There was a significant correlation between the change in EDSS or AI and the change in number of lesions on MRI and between cumulative number of lesions on MRI and cumulative change in EDSS or AI. Our findings support the validity of MRI as a measure of clinical activity and potentially as an objective quantitative outcome measure for assessing response to therapy.

Thoracoscopic cervicodorsal sympathectomy: preliminary results

PURPOSE

The purpose of this study was to determine the feasibility, safety, and efficacy of thoracoscopic cervicodorsal sympathectomy.

METHODS

From March 1990 to December 1993, we performed 21 thoracoscopic sympathectomies in 19 patients. There were 13 women and six men; age 17 to 64 years, mean 37 years. Thirteen procedures were performed on the left side and eight on the right. Indications for surgery were causalgia/reflex sympathetic dystrophy in nine patients, Raynaud's/vasculitis in six, hyperhidrosis in five, and medically refractory cardiac arrhythmia in one.

RESULTS

The T1-4 sympathetic ganglia were readily identified, dissected free, and resected thoracoscopically in 19 cases, and the T3-7 ganglia were resected with thoracoscopy in one case. One case required conversion to an open thoracotomy because of dense scar from a previous first rib resection, which obscured the anatomy. Histologic confirmation of ganglia were obtained in all 21 cases. Operative duration ranged from 1.0 to 3.5 hours. Estimated blood loss was 5 to 300 cc, mean 42 cc, median 10 cc. No patient required transfusion. All 21 patients had an excellent immediate sympathectomy response. Transient Horner's syndrome developed in two patients. Postoperative residual pneumothorax (< 10%) occurred in three cases and resolved spontaneously without further treatment. In one patient pleural effusion and pneumothorax developed, which were treated with the reinsertion of the chest tube. Postoperative pain was well controlled with oral analgesics. Hospital stay was 1 to 4 days, mean 2 days, median 1 day. Follow-up at 1 to 42 months, mean 11 months, median 6 months, showed continued evidence of sympathectomy effect in all patients, except one who died of her underlying disease 1 month after operation.

CONCLUSIONS

We conclude that thoracoscopic sympathectomy is feasible, safe, and effective. Further studies are indicated to confirm its long-term benefits and to determine optimal thoracoscopic techniques.

The isolation of a fibroblast growth inhibitor associated with perigraft seroma

PURPOSE

Perigraft seroma is a rare complication of reconstructive vascular surgery characterized by a clear, sterile fluid collection confined within a fibrous pseudomembrane around a prosthetic graft. The exact cause of this disease is unknown but involves failure of surrounding connective tissue to incorporate the graft. To understand why this occurs, we studied sera from patients with perigraft seroma for their effect on human fibroblasts. Sera from control subjects, patients with uninfected prosthetic grafts, and patients with prosthetic grafts were tested for comparison.

METHODS

Fibroblast growth was measured by radioactive thymidine uptake and hexosaminidase colorimetric cell proliferation assays. We fractionated sera with gel filtration columns and measured each fraction's effect on fibroblast growth.

RESULTS

Serum samples from patients with perigraft seroma inhibited fibroblast growth in a dose-dependent manner. In contrast, a postseroma sample, normal human sera, and sera from patients with infected and uninfected grafts showed no significant fibroblast inhibition. An inhibitory factor with a molecular weight of 2000 d was isolated from serum of patients with perigraft seroma.

CONCLUSIONS

Perigraft seroma is associated with a fibroblast inhibitor with a molecular weight of 2000 d. Further identification and characterization of this protein may lead to clinical applications in preventing and treating perigraft seroma.

A comparison of quantitative electroencephalography, computed tomography, and behavioral evaluations to localize impairment in patients with stroke and transient ischemic attacks

Brain computed tomography and a structured behavioral assessment provided a better correlation than did quantitative electroencephalography to the presence of mild stroke or transient ischemic attacks in 21 patients. When electroencephalography did not correlate well, it tended to localize too laterally or miss deep lesions. Computed tomography did not identify 2 lesions when done early after disease onset. No test was uniformly more sensitive or accurate than others. They may complement each other.

Fast spin-echo MR in the detection of vertebral metastases: comparison of three sequences

PURPOSE

To examine the relative capabilities for the detection of vertebral metastases of three available fast spin-echo sequences: T1-weighted fast spin-echo, short tau inversion recovery (STIR) fast spin-echo, and T2-weighted fast spin-echo sequences with chemical shift selective saturation pulse fat suppression.

METHODS

Fourteen patients were evaluated prospectively over a 2-month period with T1-weighted fast spin-echo (four echo train, four acquisitions, 1 min 59 sec-2 min 37 sec). STIR fast spin-echo (16 echo train, four acquisitions, 2 min 30 sec-3 min 19 sec), and T2-weighted fast spin-echo (16 echo train, 4 acquisitions, 2 min 27 sec-3 min 16 sec). For all three pulse sequences, measurements were obtained of the signal intensities of normal marrow, abnormal marrow, fat, and noise posterior to the spine. Contrast-to-noise ratios were calculated for metastases in each case. Lesions were evaluated by three observers and rated for size, location, and conspicuity.

RESULTS

Signal intensities of fat, normal marrow, and noise were highest for T1-weighted fast spin-echo sequences. STIR fast spin-echo and fat-suppressed T2-weighted fast spin-echo had approximately similar fat-suppression capabilities. Though contrast-to-noise ratios were highest overall for STIR fast spin-echo, the finding was not statistically significant and lesion conspicuity was deemed better with fat-suppressed T2-weighted fast spin-echo and T1-weighted fast spin-echo images. Discrete lesions were well identified on all three pulse sequences.

CONCLUSION

Fast spin-echo sequences appear promising for the detection of vertebral metastases. Further work should be directed toward comparison with conventional spin-echo to determine whether fast spin-echo may replace conventional spin-echo sequences for evaluation of vertebral metastases.

Continuous postoperative intra-arterial urokinase infusion in the treatment of no reflow following revascularization of the acutely ischemic limb

The loss of distal tissue perfusion sufficient for limb salvage following restoration of inflow to an acutely ischemic extremity has been referred to as the "no-reflow" phenomenon. We hypothesized that patients with no reflow and limb-threat ischemia might benefit from prolonged postoperative intra-arterial infusion of the thrombolytic agent urokinase (UK). Twelve patients with arteriographic and clinical evidence of no reflow following a lower extremity arterial thrombectomy and/or bypass procedure were treated with a continuous intra-arterial UK infusion in the immediate postoperative period. The mean duration of UK infusion was 47 hours (range 15 to 112 hours). The mean rate of infusion was 58,000 units/hr (range 30,000 to 100,000 units/hr). Seven patients required transfusion for bleeding from the treated extremity (mean 3.4 units packed cells) and one required reoperation for a groin hematoma. Plasma fibrinogen levels remained within the normal range in all patients, and no systemic bleeding complications were encountered. The intra-arterial UK infusion resulted in limb salvage in 7 of 12 patients. Six patients have viable, functional extremities at a mean follow-up interval of 24.9 months (range 6.4 to 49.7 months). One patient required below-knee amputation 6 months after treatment for progressive ischemia. The other five patients required below-knee amputation during the same hospitalization after UK failed to restore distal perfusion. The postoperative period is widely considered to be a contraindication to thrombolytic therapy. Our experience indicates that while UK may cause bleeding from the treated extremity, which in some cases requires transfusion, there is no evidence of systemic fibrinolysis or systemic hemorrhage.(ABSTRACT TRUNCATED AT 250 WORDS)

Sedimentation level in intracerebral hematoma in patients receiving anticoagulation therapy

We have described two cases of spontaneous intracerebral hematoma, characterized by sedimentation level seen on unenhanced cerebral CT, in patients receiving anticoagulation therapy. Anticoagulation or coagulopathy may be important in producing sedimentation levels. The "sedimentation level" is a more accurate term than the commonly used "blood-fluid level" or "hematocrit effect."

Very distal bypass for salvage of the severely ischemic extremity

Forty-six bypass grafts to tibial arteries distal to the ankle were performed in 35 patients for salvage of extremities threatened by gangrene or nonhealing ulcers (grade III, category 5) or ischemic rest pain (grade II, category 4). Most patients (80%) were diabetic, with severely calcified arteries, whom previously we would have considered as candidates for primary amputation. All reconstructions were performed with autologous saphenous vein. Inflow was from the common femoral artery in 5 (11%), the popliteal artery in 25 (54%), or the mid-tibial arteries in 16 (35%). Life-table analysis was used to calculate primary patency and limb salvage. Results were analyzed according to origin of inflow, outflow, or configuration of the conduit (in situ saphenous vein, n = 29 [63%], reversed saphenous vein, n = 11 [24%], or nonreversed saphenous vein, n = 6 [13%]). Overall cumulative primary graft patency at 2 years for all grafts was 72%, and the cumulative limb salvage rate was 89% for the same interval. No significant differences were seen in comparing grafts originating from the femoral or popliteal level with those arising from the tibial arteries. No significant differences were noted in graft patency or limb salvage among grafts with a posterior tibial, dorsalis pedis, or plantar artery outflow. No significant difference was noted between in situ saphenous vein grafts and reversed saphenous vein grafts. A significant decreased primary patency was noted for grafts performed with nonreversed, translocated saphenous vein. We conclude that bypass grafts to the ankle or foot vessels are beneficial and should be considered for limb salvage in extremities with gangrene, ischemic ulceration, or ischemic rest pain. In our experience, in situ saphenous vein grafts or reversed saphenous vein grafts performed similarly, whereas nonreversed saphenous vein grafts have a poorer prognosis. Vessel wall calcification requires a modification in technique for performance of these grafts but did not affect long-term performance or limb salvage, and thus should not be considered a contraindication to vascular reconstruction. The operative microscope was used in 61% (28 of 46) of these cases and found useful in creating these delicate anastomoses. Additional follow-up is needed to document the long-term results of these very distal reconstructions.

Transobturator aorto-profunda femoral artery bypass using the direct medial thigh approach

We present a novel technique for aorto-profunda femoral artery bypass using both the obturator foramen and the direct medial thigh approach to the profunda femoral artery in a patient with an infected femoral graft and limb-threatening ischemia. This patient has undergone multiple bypass grafts to salvage function of his lower extremities, but these standard anatomic and extra-anatomic bypasses had failed because of graft infections. The technique as well as the surgical anatomy are described. The combination of the transobturator aorto-profunda femoral artery bypass and the direct medial approach to the profunda femoral artery is technically feasible, provides adequate outflow for limb salvage in selected patients with good collateral arteries, offers acceptable long-term patency, and is particularly useful when the groin is hostile to dissection or graft material and the superficial femoral and popliteal arteries are occluded.

Endovascular obliteration of in situ saphenous vein arteriovenous fistulas during tibial bypass

Current methods of ligating venous branches during in situ vein tibial bypass are associated with significant wound complications, especially in diabetics. Making only proximal and distal wound incisions could avoid these wound problems. We report the use of endovascular techniques with coils and balloons guided by intraoperative arteriography and angioscopy to obliterate arteriovenous (AV) fistulas in three elderly diabetic patients undergoing tibial bypass. In all cases the proximal and distal vessels were first isolated and deemed suitable for bypass. The greater saphenous vein was prepared for the proximal and distal anastomosis, and angioscopically guided valvulotomy was performed. An introducer sheath was placed through a large proximal saphenous side branch for vascular access. With the use of fluoroscopy, AV fistulas were serially identified and cannulated with a guidewire. A guide catheter, passed over the wire into the side branch, served as the conduit through which coils and balloons were placed. Proximal and distal anastomoses were completed and arteriography performed. We were successful in obliterating AV fistulas in all three patients, but completion arteriography revealed additional AV fistulas requiring surgical ligation in two patients. Furthermore, operative time was increased by 1 1/2 to 5 hours. Two of three patients had wound infections, one at the proximal and one at the distal incision. All patients were discharged with a functioning bypass and no AV fistulas were seen on duplex scans. Endovascular obliteration of AV fistulas is feasible but is currently limited by prolonged operative time and incomplete obliteration.

Imaging of neurologic complications associated with pregnancy

The occurrence of a neurologic event during pregnancy or the puerperium may have devastating consequences for mother and child. It is imperative that the radiologist be familiar with the entities likely to be encountered in pregnancy so that these patients can be examined rapidly and efficiently. The importance of early and accurate diagnostic imaging is underscored by the fact that most patients are otherwise young and healthy, and prompt institution of appropriate therapy can result in complete recovery. In this report, we illustrate some of the more common neurologic complications that occur during pregnancy and the immediate postpartum period.

Endovascular surgery for peripheral arterial occlusive disease

Endovascular surgery includes angiography, balloon angioplasty, laser angioplasty, mechanical atherectomy and stent placement. Both diagnostic and therapeutic procedures are possible. The advantages of endovascular techniques include the ability to precisely and noninvasively remove an atherosclerotic lesion without producing damage to the surrounding vascular wall. Endovascular techniques have minimal complications, involve minimal blood loss and can be performed as outpatient procedures. Drawbacks include disappointingly high rates of restenosis, limitations on the type of lesion that can be treated successfully and only partial visualization of an atherosclerotic lesion with some devices.

The effects of photofrin on human Tenon's capsule fibroblasts in vitro

Pharmacological agents that modulate the wound healing process by inhibiting fibroblast proliferation may improve the success of proliferative vitreoretinopathy and glaucoma filtration surgery and may have applications in other surgical fields. It is possible that light-absorbing chemicals can be used to cause photo reactions in proliferating fibroblasts as a means of controlling this wound healing process. We present the effects of photofrin porfimer sodium (serial tenfold dilutions 1000-0.00001 micrograms/ml) on human fibroblasts from Tenon's capsule in vitro, with and without photoactivation with Argon green laser (700 mW for 1 and 5 minutes) and with bright sunlight (for 1 and 5 min). The cell density was measured on day 2 by 3H-thymidine uptake and on day 9 by means of a coulter counter, and optical density was measured in terms of the activity of the enzyme hexosaminidase. Each experiment was performed three times in quadruplicate. The counts were averaged for each drug concentration and mean cell count with a standard error as well as the 50% inhibitory doses (ID50s) were calculated. Photofrin demonstrated an inhibitory dose response curve (dark toxicity) to human fibroblasts. Concentrations greater than 100 micrograms/ml of photofrin alone completely inhibited cell growth. Concentrations less than 0.01 micrograms/ml did not have any effect on fibroblast proliferation. There was no significant log dose shift of the inhibitory effect of photofrin with the exposure to either sunlight or Argon laser. Photofrin may be used as a cytotoxic agent alone but does not appear to be activated by light to modulate subconjunctival fibroblast proliferation within the laser parameters used.

Inhibition of intimal hyperplasia by photodynamic therapy using photofrin

Photodynamic therapy using photofrin and light energy inhibits human myofibroblast proliferation in cell culture. The purpose of this study is to evaluate its influence on intimal hyperplasia in vivo. Twenty New Zealand White rabbits underwent a standardized intimal injury to both common carotid arteries with a 2 Fr balloon catheter. One week later, half of the animals received photofrin (5 mg/kg) intravenously. The remaining 10 rabbits received no photofrin. Two days later, all neck incisions were reopened and a 1-cm segment of each of the 40 carotid arteries was exposed for 5 min to 80 mW of 630 nm light energy from a continuous wave tunable dye laser (fluence = 7.6 J/cm2). All vessels were harvested 5 weeks post-laser treatment following in vivo fixation with formalin. From each artery, separate cross-sections taken from both the lasered and non-lasered regions of each vessel were mounted and stained for histologic evaluation. Analyzed segments were then divided into four different treatment groups: group I segments consisted of arterial cross-sections which were taken from vessel regions that were injured but received neither photofrin nor laser treatment (group I, n = 20); group II segments also did not receive photofrin but were exposed to light energy (group II, n = 20); group III segments received photofrin but no light energy (group III, n = 20); and cross-sections in group IV were taken from those segments which received both photofrin and laser treatment. Using planimetry, the ratio of the area of intimal hyperplasia (IH) to the area enclosed by the internal elastic lamina (IEL) was measured for each specimen (IH/IEL).(ABSTRACT TRUNCATED AT 250 WORDS)