Finite Element Analysis of the Cutting Balloon With an Adequate Balloon-to-Artery Ratio for Fracturing Calcification While Preventing Perforation

Successful Endovascular Treatment of Calcified Superior Mesenteric Artery Complicated by Intramural Hematoma in Chronic Mesenteric Ischemia

BACKGROUND Chronic mesenteric ischemia (CMI) is defined as ischemic symptoms caused by insufficient supply of blood to the gastrointestinal tract. Patients diagnosed with advanced symptomatic CMI should be treated subsequently, as the transition from CMI to acute mesenteric ischemia can be unpredictable. However, there is little information regarding the management of potential procedural complications during endovascular therapy (EVT) for CMI. CASE REPORT A 70-year-old man was admitted to our hospital with recurrent abdominal pain just after hemodialysis. The angiogram showed significant stenosis with heavy calcification in the proximal of the superior mesenteric artery (SMA), leading to the diagnosis of CMI. To alleviate the symptom, EVT for the stenotic lesion of the SMA was indicated. During the procedure, a cutting balloon was inflated to facilitate vessel expansion in the target lesion. As a result, intravascular ultrasound (IVUS) imaging revealed dissection into the media with extension into the medial space without reentry and demonstrated a semilunar intramural hematoma. We were able to contain the intramural hematoma by covering the whole dissection in the SMA with implantation of self-expandable stents. CONCLUSIONS This case highlights the potential of EVT for heavy calcification of the SMA complicated by dissection without reentry. Intramural hematoma was observed with IVUS examination. We were able to contain the hematoma by the implantation of self-expandable stents over the whole length of the SMA dissection under IVUS-guided EVT.

Investigating Balloon-Vessel Contact Pressure Patterns in Angioplasty: In Silico Insights for Drug-Coated Balloons

Drug-Coated Balloons have shown promising results as a minimally invasive approach to treat stenotic arteries, but recent animal studies have revealed limited, non-uniform coating transfer onto the arterial lumen. In vitro data suggested that local coating transfer tracks the local Contact Pressure (CP) between the balloon and the endothelium. Therefore, this work aimed to investigate in silico how different interventional and device parameters may affect the spatial distribution of CP during the inflation of an angioplasty balloon within idealized vessels that resemble healthy femoral arteries in size and compliance. An angioplasty balloon computational model was developed, considering longitudinal non-uniform wall thickness, due to its forming process, and the folding procedure of the balloon. To identify the conditions leading to non-uniform CP, sensitivity finite element analyses were performed comparing different values for balloon working length, longitudinally varying wall thickness, friction coefficient on the balloon-vessel interface, vessel wall stiffness and thickness, and balloon-to-vessel diameter ratio. Findings indicate a significant irregularity of contact between the balloon and the vessel, mainly affected by the balloon's unfolding and longitudinal thickness variation. Mirroring published data on coating transfer distribution in animal studies, the interfacial CP distribution was maximal at the middle of the balloon treatment site, while exhibiting a circumferential pattern of linear peaks as a consequence of the particular balloon-vessel interaction during unfolding. A high ratio of balloon-to-vessel diameter, higher vessel stiffness, and thickness was found to increase significantly the amplitude and spatial distribution of the CP, while a higher friction coefficient at the balloon-to-vessel interface further exacerbated the non-uniformity of CP. Evaluation of balloon design effects revealed that the thicker tapered part caused CP reduction in the areas that interacted with the extremities of the balloon, whereas total length only weakly impacted the CP. Taken together, this study offers a deeper understanding of the factors influencing the irregularity of balloon-tissue contact, a key step toward uniformity in drug-coating transfer and potential clinical effectiveness.

Cutting balloon to optimize predilation for stent implantation: The COPS randomized trial

OBJECTIVES

The objective of this study is to investigate the use of cutting balloon (CB) inflated at high pressure compared with noncompliant balloon (NCB) for the treatment of calcified coronary lesions.

BACKGROUND

No data are available regarding the safety and efficacy of CB inflated at high pressure in coronary artery calcifications.

METHODS

Patients with calcified lesions (more than 100° of calcium demonstrated at baseline intravascular ultrasound) were randomized. Primary endpoint of the study was the final minimal stent area (MSA) and stent symmetry in the calcific segment. Secondary endpoints included rate of device failure and the 1-year rate of target lesion revascularization, target vessel revascularization, and major adverse cardiovascular events.

RESULTS

From September 2019 to June 2021, a total of 100 patients were included and randomized; 13 patients were excluded for major protocol deviations. Lesions were complex (type B2/C n = 61 [71.2%]) with a mean arch of calcium of 266 ± 84°, a calcium length of 12 ± 6.6 mm. CB was inflated at comparable atmospheres when compared with NCB (18.3 ± 5 vs. 19 ± 4.5, p = 0.46). In the per-protocol population, the final MSA at the level of the calcium site was significantly higher in the CB group (8.1 ± 2 vs. 7.3 ± 2.1, p = 0.035) with a higher eccentricity index achieved in the CB group (0.84 ± 0.07 vs. 0.8 ± 0.08, p = 0.013). Three device failure occurred in the CB group. One-year follow-up outcomes were comparable.

CONCLUSIONS

Treatment of calcified lesions with high-pressure CB has a good safety profile and is associated with a larger MSA and higher eccentricity of the stent at the level of the calcium site compared with NCB.

Factors in Sufficient Endovascular Vessel Preparation for Severely Calcified Femoropopliteal Lesions

BACKGROUND

Vessel preparation for endovascular treatment (EVT) is important but because the contributory factors for favorable outcomes are not yet known, we conducted the present study to elucidate the factors associated with sufficient vessel preparation for severely calcified femoropopliteal (FP) lesions.Methods and Results: This was a single-center retrospective observational study of 97 patients (mean age, 75±8 years, 76% male) with 106 de novo severely calcified FP lesions who underwent EVT under intravascular ultrasound (IVUS) evaluation. The lesion definition was 360° of superficial calcification on IVUS. The primary outcome measure was sufficient vessel preparation, which was defined as successful cracking of severely calcified lesions evaluated by IVUS after predilation. The mean lesion length was 200±103 mm, and chronic total occlusion was present in 38% of patients. According to the greater difference between the preballoon size and the lumen diameter of the severely calcified lesion, the frequency of sufficient vessel preparation increased (odds ratio, 4.68; 95% confidence interval, 2.09-10.49; P<0.01). Balloon type (noncompliant, P=0.80; scoring: P=0.25) and pressure (P=0.27) were non-contributory.

CONCLUSIONS

The difference between the lumen diameter at the severely calcified FP lesion site and the preballoon dilatation diameter was the sole factor contributing to sufficient vessel preparation.

Wolverine cutting balloon in the treatment of stent underexpansion in heavy coronary calcification: bench test using a three-dimensional printer and computer simulation with the finite-element method

Heavy coronary calcification hinders successful stent implantation, and cutting balloons can be used for post-dilation after stent deployment. However, evidence regarding its use is limited to case reports. Therefore, this study aimed to investigate in-stent dilation in circumferential coronary calcifications using Wolverine cutting balloons, compared with conventional non-compliance (NC) balloons. Circumferential coronary calcification models were designed based on the patient's intravascular ultrasound images. Three-dimensional printed models were subjected to bench tests and software analysis was performed using the finite-element method (FEM). As a result, the bench test showed that higher balloon pressure was needed to dilate the models with stent implantation, either using Wolverine (17.1 ± 2.7 atm) or NC Emerge (18.9 ± 1.8 atm), while lower pressure was needed in models without stents using Wolverine [11.7 ± 2.9 atm, analysis of variance (ANOVA) p < 0.001]. Furthermore, models without stents were all successfully cracked by Wolverine at the first dilation, while models with stent implantation needed more dilations (ANOVA p = 0.0132). The FEM showed similar results that the first principal stress was the highest in Wolverine-dilated models without stents. In conclusion, implanted stents significantly increase the difficulty of balloon dilation and adequate pretreatment is critical for successful coronary stenting.