Magnetic Resonance Angiography-based Prediction of the Results of Balloon Test Occlusion

A patient-specific circle of Willis blood flow model in predicting outcomes of balloon test occlusion

BACKGROUND AND PURPOSE

Balloon test occlusion (BTO) evaluates cerebral ischemic tolerance before internal carotid artery (ICA) sacrifice but carries risks like dissection and thrombosis. This study introduces a new approach using a patient-specific circle of Willis (COW) blood flow model, based on non-invasive quantitative MR angiography (qMRA) measurements, to predict the outcomes of BTO.

METHODS

We developed individualized COW blood flow models for 43 patients undergoing BTO. These models simulated blood flow and pressure under normal conditions and with the ICA occlusion. We then compared the model's predictions of blood flow changes due to the simulated ICA occlusion to actual qMRA measurements before the BTO.

RESULTS

For all 31 BTO failures, the ipsilateral hemisphere showed an average flow decrease of 15 ± 10% (mean ± standard deviation), compared to 3 ± 2% in the contralateral hemisphere. In all 12 BTO passes, these figures were 6 ± 3% and 1 ± 0.8%, respectively. Notably, all BTO passes had less than a 10% reduction in the ipsilateral hemisphere. In contrast, 65% of BTO failures and 67% single-photon emission computed tomography (SPECT) failures exhibited a decrease of 10% or more in the same region.

CONCLUSION

Blood flow reduction exceeding 10% in the ipsilateral hemisphere during BTO is a strong predictor of failure in both BTO and SPECT. Our patient-specific COW blood flow models, incorporating detailed flow and arterial geometry data, offered valuable insights for predicting BTO outcomes. These models are especially beneficial for situations where conducting BTO or SPECT is clinically impractical.

Perioperative and long-term complications following therapeutic internal carotid artery occlusion

BACKGROUND

Parent artery occlusion (PAO) is an effective treatment for hemorrhagic diseases associated with the internal carotid artery. There are several reports of long-term cerebral infarction or the formation of de novo cerebral aneurysms following PAO.

MATERIALS AND METHODS

We retrospectively reviewed these complications in 38 patients who underwent PAO for therapeutic treatment. We investigated perioperative cerebral infarctions, long-term cerebral infarctions, and de novo aneurysms.

RESULTS

The mean age of the patients was 64.0 years, and 25 patients (65.8%) were female. The causative diseases were unruptured (n = 19; 50.0%) and ruptured (n = 8; 21.1%) aneurysms. PAO was performed after ischemic tolerance was assessed with balloon test occlusion (BTO), and BTO was performed in 34 patients, of whom 25 (73.5%) had ischemic tolerance. Twenty-six patients (68.4%) were treated with PAO alone, eight (23.5%) with low-flow bypass, and six (17.6%) with high-flow bypass. Perioperative complications occurred in five patients (13.2%): two of the 26 patients (7.7%) who underwent scheduled treatment and three of the 12 patients (25.0%) who underwent emergency treatment. One patient (2.6%) had long-term de novo aneurysm, and none developed cerebral infarction.

CONCLUSIONS

These results showed that the assessment of ischemic tolerance by performing BTO and appropriate revascularization in scheduled treatments are important to reduce perioperative and long-term cerebral infarctions. PAO must be performed with greater caution in emergency treatment.

The Sutureless Excimer Laser Anastomosis Clip Pilot Study: a feasibility and safety study

BACKGROUND

The excimer laser-assisted non-occlusive anastomosis (ELANA) bypass technique may have the advantage of its non-occlusive design in the treatment of last-resort cases where endovascular treatment or direct clipping is considered to be unsafe. However, the technique remains technically challenging. Therefore, a sutureless ELANA Clip device (SEcl) was developed to simplify the technique avoiding tedious anastomosis stitching in depth. The present study investigates the clinical feasibility and safety of the SEcl technique.

METHODS

Three patients with complex and large aneurysms in the anterior circulation were selected after multidisciplinary consensus that the aneurysms were too complex for endovascular or direct clipping treatment options. Bypass surgery was considered as a last-resort treatment option, and after preoperative evaluation and informed consent, SEcl bypass surgery was performed. Applicability, technical aspects and patient outcomes are assessed.

RESULTS

All aneurysms were excluded from the circulation. The creation of the intracranial anastomosis was easier and faster. No device-related serious adverse events were encountered, and all outcomes were favorable (one patient stable Modified Rankin Scale, two patients improved).

CONCLUSION

The SEcl anastomosis technique is feasible and, considering the severity of the disease, relatively safe. It can be considered a treatment option in very difficult-to treat last-resort aneurysm cases. From this study, further developments in minimizing clip size and application in cardiac surgery are initiated.

Emergency extra-intracranial bypass surgery in a patient with neurologic deficit after an accident in carotid occlusive test: A case report

OBJECTIVE

BTO is the procedure performed to assess the collateral circulation within the Willis circle in a giant ICA aneurysm. An ICA occlusion after BTO is very rare. We present a case of an internal carotid artery occlusion as a complication of BTO that required urgent revascularization surgery.

CASE PRESENTATION

A 56-year-old female with a history of transient ischemic attacks for one year was diagnosed with multiple aneurysms: a giant aneurysm of the left supra-clinoid ICA, two small ones on left MCA and right ophthalmic. A BTO was performed to assess collateral supply and determine whether bypass surgery should be necessary. During the procedure, the balloon was detached while insufflating, and the patient had a subsequent neurological decline consistent with an MCA syndrome. EC-IC bypass surgery was performed with an end-to-side anastomosis of STA-MCA by trapping the giant aneurysm and clipping the ipsilateral MCA aneurysm. The patient had a reversal of neurological symptoms and made an uneventful recovery.

DISCUSSION

We discuss the epidemiology of giant ICA aneurysms, the indications for BTO, and its complication. Emergency intracranial and extracranial bypass surgery in case of acute ICA injury is also discussed. We also highlighted the attributable factors to treatment strategies under restrictive conditions in Vietnam.

CONCLUSIONS

ICA occlusion due to insufflated balloon detachment is an unreported complication in literature. Emergency bypass surgery is a potential treatment choice for this unusual iatrogenic complication.

Ophthalmic Artery Flow Pattern-related Stump Pressure and Ischemic Tolerance during Balloon Test Occlusion of the Internal Carotid Artery

Very few studies have described the blood flow pattern in the ipsilateral ophthalmic artery (OphA) during internal carotid artery (ICA) balloon test occlusion performed to estimate the risk of cerebral ischemia associated with therapeutic ICA sacrifice. This study aimed to investigate the relationship between ipsilateral OphA flow patterns just after ICA temporary occlusion and balloon test occlusion findings. We retrospectively reviewed 32 balloon test occlusion procedures performed at our institution between 2010 and 2019, and analyzed the OphA flow patterns and the conventional balloon test occlusion assessment items: neurological symptoms, stump pressure, stump-pressure ratio, collateral circulations, and venous phase delay. The flow patterns were categorized as type I (retrograde flow reaching the middle cerebral artery [MCA]), type II (retrograde flow to the ICA not reaching the MCA), or type III (no retrograde flow). Tolerance to balloon test occlusion was observed in 4/21 patients (19.0%), 4/6 patients (66.7%), and all five patients with types I, II, and III flows, respectively. The mean pressure ratios during balloon test occlusion in flow types I, II, and III were 35.6% ± 3.5%, 56.4% ± 6.5%, and 69.4% ± 7.1%, respectively (P <0.001). The mean stump pressures in flow types I, II, and III were 36.2 ± 3.6 mmHg, 46.6 ± 6.7 mmHg, and 66.6 ± 7.3 mmHg, respectively (P = 0.003). The mean venous phase delay in flow types I, II, and III were 0.99 ± 0.14 s, 0.25 ± 0.25 s, and 0.0 ± 0.28 s, respectively (P = 0.004). All the above variables showed significant flow-related differences. These results suggest that the OphA flow patterns may provide an additional diagnostic criterion for balloon test occlusion.