Exploiting the Transformation Temperature to Reform an Infolded Nitinol Self-Expanding Peripheral Stent

Purpose: Nickel-titanium (nitinol) alloys possess a special set of properties that allow for a wide range of applications. Specifically, the transformation temperature for self-expanding nitinol peripheral stents allows for easy crimping at or below room temperature and reformation at body temperature becoming superelastic. Case Report: We report the case of an elderly man with iliac stenting 1 month prior, who presented several weeks after recovering from coronavirus disease 2019 with recurrent anterior-wall ST-elevation myocardial infarction. This was complicated by deformation and infolding of the previously implanted nitinol self-expanding stent in his right common iliac artery (CIA). Understanding nitinol’s specific properties, we proceeded with rapid injections of iced saline to cool the nitinol stent to its transformation temperature while nudging the distal end of the stent with a partially inflated balloon. This maneuver softened the nitinol stent, allowing us to “unfold” and reappose it against the wall of the right CIA, resulting in successful restoration of the original shape of the nitinol self-expanding stent. Conclusion: This represents the first reported case describing treatment of an infolded nitinol self-expanding peripheral stent by exploiting the transformation temperature of nitinol using iced cold saline to successfully restore the stent’s original shape and structure.

Rescue embolization with direct coil delivery from dual-lumen balloon microcatheter

Background Balloon microcatheters are widely used for endovascular treatment. However, no reports on direct coil embolization from dual-lumen balloon microcatheters are available in the literature. This report is the first description of direct coil embolization using this type of balloon microcatheter for looming bleeding emergencies. Methods This retrospective review demonstrates the indications and advantages of coil embolization from an inflated balloon catheter to reduce blood loss and simultaneously occlude bleeding. Results Five patients who underwent emergency endovascular treatment using coil embolization directly delivered from a dual-lumen balloon were identified. Etiologies included vertebro-vertebral arteriovenous fistula, ruptured vertebral artery dissecting aneurysm, vertebral artery injury during cervical spinal operation, and failed stent retrieval procedures for acute infarction. Complete hemostasis was achieved with all procedures. Conclusion Our experience demonstrates the feasibility of direct coil embolization by using a dual-lumen balloon to rapidly halt bleeding in some rare emergency situations, which may save lives.

Percutaneous Mitral Balloon Valvuloplasty: Technique and Results

Background: Percutaneous balloon mitral valvuloplasty is a procedure used to dilate the mitral valve in cases of rheumatic mitral stenosis. The catheter is inserted into the female vein to the right atrium and atrial septum. The mitral valve is then passed through the inflated balloon to facilitate effective integration of mitral adhesions, which increases the area of the mitral valve and decreases the rate of mitral stenosis. Mitral regurgitation is a potential problem, and thus balloon percutaneous mitral valvuloplasty (PBMV) is prevented in moderate to severe relapse. The Wilkins score studies mitral valve morphology and evaluation by echocardiography to assess the viability of PBMVs based on specific echocardiographic conditions. Conclusion: There are many factors in the immediate and long-term outcomes of patients undergoing PMV. Echo-Sc can be used in combination with other clinical and morphological predictions of PMV effects to identify patients who experience the best effects on PMV.

Retrograde Angiography to Detect Dropped Thrombus in Mechanical Thrombectomy

Objective The risk of embolization to distal territory or to new territory in mechanical thrombectomy remains a major issue despite advancements in technological device. This condition can be caused by a large and firm dropped thrombus without passing through a guiding catheter during stent retriever or aspiration catheter withdrawal. This report introduced a novel technique referred to as retrograde angiography to detect dropped thrombus. Methods The retrograde angiography to detect dropped thrombus technique is a kind of retrograde angiography that consists of a contrast medium injection via a distal microcatheter and aspiration through an inflated balloon-guiding catheter. This method was used to detect dropped thrombus at the balloon-guiding catheter tip when back flow was blocked from the balloon-guiding catheter after stent retriever or aspiration catheter withdrawal. We retrospectively reviewed four consecutive patients who underwent the retrograde angiography to detect dropped thrombus technique during mechanical thrombectomy for acute ischemic stroke due to large vessel occlusion in the anterior circulation between January 2018 and January 2021. Results Three of four patients had dropped thrombus, which was diagnosed with the technique and retrieved completely with subsequent procedures while maintaining the balloon-guiding catheter inflated. None of the patients experienced embolization to distal territory/embolization to new territory, and a successful reperfusion was achieved in all four cases. Conclusions The retrograde angiography to detect dropped thrombus is a technique to detect a dropped thrombus at the balloon-guiding catheter tip and allows us to retrieve it with subsequent mechanical thrombectomy procedures while maintaining the balloon-guiding catheter inflated and it may be useful for reducing the risk of embolization to distal territory/embolization to new territory.

Effect of Balloon Embedded Bifurcating Stenting with Single Stent Strategy for Side Branch Protection

Background: Intervention for bifurcation lesions is associated with increased risk of adverse events and includes acute side branch (SB) occlusion during main branch (MB) stenting. This acute occlusion of side branch can often be catastrophic for the patient. We here in describe our experience in National Institute of Cardiovascular Diseases and Hospital (NICVD), Dhaka, Bangladesh with a technique which can be incorporated into bifurcation stenting to reduce or almost eliminate the incidence of side branch occlusion or catastrophe. Methods: A prospective, observational, non-blinded study in patients from a single tertiary referral cardiac center National Institute of Cardiovascular Diseases & Hospital (NICVD), Dhaka, Bangladesh. Patients with an indication for percutaneous coronary intervention (PCI) of a denovo bifurcation lesion were screened. The study included 51 patients who underwent coronary angiogram in our institution and had bifurcation lesions suitable for single stent strategy between March 2017 to September 2018. Results: 51 patients with bifurcation lesion were included in the study and underwent a balloon embedded bifurcation stenting with a semi inflated balloon placed across the SB ostium. Angiographic success was achieved in all the patients but procedural success was achieved in 88.2% of the patients. TIMI 3 flow of main branch (MB) was achieved 96.08% and side branch (SB) was achieved 88.2%. Incidence of dissection was 5.9%, acute occlusion of SB was 2.0% and MACE was 3.9%. Mean fluoroscopy time and contrast volume was similar to that of conventional bifurcation stenting. The jailed SB balloon and wire could be successfully removed in all patients. Conclusion: The present study suggests that balloon embedded bifurcation stenting with a semi inflated balloon to protect the SB is feasible, with minimal procedural adverse events and successful in minimizing or almost eliminating the incidence of acute side branch occlusion or dissection as well as MACE. Bangladesh Heart Journal 2021; 36(1): 17-23

Horses show individual level lateralisation when inspecting an unfamiliar and unexpected stimulus

Animals must attend to a diverse array of stimuli in their environments. The emotional valence and salience of a stimulus can affect how this information is processed in the brain. Many species preferentially attend to negatively valent stimuli using the sensory organs on the left side of their body and hence the right hemisphere of their brain. Here, we investigated the lateralisation of visual attention to the rapid appearance of a stimulus (an inflated balloon) designed to induce an avoidance reaction and a negatively valent emotional state in 77 Italian saddle horses. Horses’ eyes are laterally positioned on the head, and each eye projects primarily to the contralateral hemisphere, allowing eye use to be a proxy for preferential processing in one hemisphere of the brain. We predicted that horses would inspect the novel and unexpected stimulus with their left eye and hence right hemisphere. We found that horses primarily inspected the balloon with one eye, and most horses had a preferred eye to do so, however, we did not find a population level tendency for this to be the left or the right eye. The strength of this preference tended to decrease over time, with the horses using their non-preferred eye to inspect the balloon increasingly as the trial progressed. Our results confirm a lateralised eye use tendency when viewing negatively emotionally valent stimuli in horses, in agreement with previous findings. However, there was not any alignment of lateralisation at the group level in our sample, suggesting that the expression of lateralisation in horses depends on the sample population and testing context.

Pediatric Sized REBOA Catheter Testing in a Pulsatile Aortic Flow Model

Background – Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) in the management of pediatric abdomino-pelvic hemorrhage from trauma or iatrogenic injury is limited by a lack of appropriately sized balloon catheters that can be delivered through less than a 7 French sheath. Methods – We bench tested the occlusion capability of eight commercially available balloon catheters deliverable through 4Fr, 5Fr and 6Fr sheaths in an anatomic pulsatile flow model of the pediatric aorta with variable luminal diameters (5mm, 6mm, 7mm, 8mm, 9mm, 10mm, and 12mm). Inflated balloon migration and the deflated balloon’s effect on aortic flow were recorded. The flow chamber was calibrated to approximate size-appropriate physiologic aortic blood flow. Results – Seven of eight devices were able to occlude the test lumen diameter corresponding to their manufacture specifications. Deflated luminal flow restriction in the smallest test lumen was lowest in the Fogarty devices (0-3%) followed by Cordis (8-10%) and Numed (14-26%) devices. The Fogarty devices demonstrated the most distal migration (10-15mm) followed by Numed (1-5mm). Device migration was undetectable in the Cordis devices. Conclusion – There are commercially available balloon catheters, deliverable through smaller than 7Fr sheaths which can occlude pediatric sized aortic test lumens in the setting of physiologic pulsatile flow. These results will help inform future research, device development and practice in the field of pediatric REBOA.

Microcatheter Stabilization Technique Using Partially Inflated Balloon for Coil Embolization of Paraclinoid Aneurysms

Purpose: Coil embolization of paraclinoid aneurysms should be simple, safe, and effective considering the benign nature of the aneurysm. Here, we present a microcatheter stabilization technique using a partially inflated balloon for the treatment of paraclinoid aneurysms.Materials and Methods: This retrospective study included 58 patients who underwent balloon-assisted coiling (BAC) for unruptured paraclinoid aneurysms at a tertiary neuro-intervention center between January 2019 and March 2020. We applied a technique to stabilize the microcatheter’s position using the modified BAC technique in paraclinoid aneurysms showing various projections around the ophthalmic curve of the internal carotid artery. The basic concept of the technique is to place a partially inflated balloon just distal to the aneurysm neck and support the distal curve of the microcatheter using the proximal bottom of the balloon. Immediate radiological outcomes were analyzed, and clinical outcomes were evaluated with modified Rankin Scale (mRS) scores.Results: The BAC was successfully performed in 51 of 58 patients (88%). We treated the remaining seven patients by switching to stent-assisted coiling. We obtained a 37% mean packing density resulting in favorable occlusion in all 58 aneurysms (complete occlusion in 35 and residual neck in 23). There were no intraprocedural thromboembolic or hemorrhagic events except one that revealed an asymptomatic infarction after the procedure (1.7%). Magnetic resonance angiography follow-up was performed in 37 patients at an average of 11.8 months, in which 11 minor recurrences (29.7%) were found. There was no major recurrence nor retreatment. The mRS score was 0 in all patients during a mean follow-up of 17.7 months (range, 12–25 months).Conclusion: The modified balloon-assisted coiling technique using a partially inflated balloon was safe and effective and could serve as an option for treating paraclinoid aneurysms.

The Transformation of the Balloon Shape in Percutaneous Balloon Compression for Trigeminal Neuralgia

Background: The pear shape of an inflated balloon is thought to be a gold standard of a successful percutaneous balloon compression (PBC). However, neither how the balloon shape changes nor why it changes in that way (the anatomic basis) has not yet been fully described. Methods: Radiographs from over 150 percutaneous balloon compression (PBC) cases were thoroughly evaluated. We proposed a model of changing balloon shape in Meckel's cave (MC) and 70 cases were followed up over 2 years, in which therapeutic effect was measured.Results: We found that the balloon changed stereotypically in MC. The model that we proposed is consistent with the description of the structures of MC and its surroundings in the literature. The distinct pear (pear in MC) brought about a far better surgical result than other shapes (p < 0.01).Conclusion: Our study showed how and why the balloon shape changed during PBC surgery. The model provides favorable guidance for PBC surgery.