Chronic arterial occlusion in a canine model: a novel technique

Birth and Growth of Neuroimaging and Vascular Intervention at Sree Chitra Tirunal Institute for Medical Sciences & Technology, Thiruvananthapuram—Part I

This article is a historical narrative that traces the growth of neuroradiology and interventional radiology at the Sree Chitra Tirunal Institute of Medical Sciences and Technology, Thiruvananthapuram. From its humble origins in the pre-CT scan era of the mid and late 1970s, when invasive diagnostic procedures such as percutaneous carotid angiography, myelography, pneumoencephalography (PEG) and ventriculography were the mainstay of neuroimaging, the authors take the reader through their gradual foray into catheter four-vessel angiography and later free-flow embolization of arteriovenous malformations (AVMs), and finally to the use of microcatheters for selective embolization procedures. The equipment used in those early years—fluoroscopic tilting table, roll-film cameras, serial changers, PEG tables—provide an insight to an era with all its challenges before the advent of digital imaging. The authors’ efforts to indigenize some of the hardware such as metallic stents and embolization material such as hydrogel spheres and lyophilized dura are also highlighted. The development of peripheral vascular intervention alongside neuroradiology is also highlighted. The authors pay tribute to an early pioneer of neuroradiology in India, Prof. Mahadevan Pillai, who was a guiding light to them during those nascent years.

Evaluation of thrombolysis and angioplasty in a porcine iliac artery thrombosis model: application of endovascular stent-graft-induced thrombosis

PURPOSE

To develop a novel endovascular thrombosis model in the porcine iliac artery for the evaluation of thrombolysis and angioplasty.

MATERIALS AND METHODS

A stent-inversion-graft (SIG) model combining either a 3-mm or 5-mm tapered expandable polytetrafluoroethylene (ePTFE) graft attached within a self-expandable, 10-mm nitinol stent was placed in the left common iliac artery via an ipsilateral common femoral artery approach in 24 pigs. When the iliac artery was thrombosed, urokinase (250,000 IU) plus heparin (1,000 units) were pulse sprayed via a contralateral femoral approach (n = 12). Saline pulse-spray was used as a control group (n = 12). Balloon angioplasty was performed to eliminate the stenotic tapered graft within the stent after successful thrombolysis. The efficacy of the thrombolysis was assessed with use of intravascular ultrasound (IVUS) and arteriogram.

RESULTS

Both the 3-mm tapered and 5-mm tapered SIG models caused iliac artery occlusion in 22 +/- 5 and 41 +/- 9 minutes, respectively, after the deployment. Luminal patency was re-established successfully in all occluded arteries after urokinase infusion. Angioplasty was successful in eliminating the tapered stenosis and restoring the normal diameter in all iliac arteries treated with urokinase. Complete thrombolysis was achieved in both models treated with urokinase.

CONCLUSION

This novel endovascular approach of inducing arterial thrombosis is simple to perform and reliably produces arterial thrombosis. The intraluminal stenosis is also amenable to angioplasty. This model is useful for the evaluation of antithrombotic treatment modality and adjunctive endovascular interventions.

A porcine model of chronic peripheral arterial occlusion

PURPOSE

To create a simple and reproducible model of chromic thrombosis for the evaluation of thrombolytic agents and devices.

MATERIALS AND METHODS

A stenosis was created in the superficial femoral artery of domestic swine, and autologous blood clot was deposited above the stenosis. Follow-up last for up to 3 months. Degree of clot organization was determined at histologic examination. Two thrombolytic agents, urokinase and collagenase, were used to test this model.

RESULTS

There was a 27% delayed recanalization rate with this model. At histologic examination, early thrombus organization was seen at the vessel periphery after 10 days. One-month-old thrombus was substantial but variable in amount. Three-month-old thrombus was completely organized. Neither urokinase nor collagenase proved effective against chronic clot in the doses and time course of this study.

CONCLUSION

This simple method yields a chronic porcine clot in a reliable number of domestic swine in 1 month.