Utility of a scoring balloon for a severely calcified lesion: bench test and finite element analysis

Effectiveness and Safety of a Novel Intravascular Lithotripsy System for Severe Coronary Calcification: The CALCI-CRACK Trial

BACKGROUND

Intravascular lithotripsy is effective and safe for managing coronary calcification; however, available devices are limited, and complex lesions have been excluded in previous studies. This study aimed to investigate the effectiveness and safety of a novel intravascular lithotripsy system for severe calcification in a population with complex lesions.

METHODS

CALCI-CRACK (treatment of severe calcified coronary lesions with a novel intracoronary shock wave lithotripsy system) (ChiCTR2100052058) was a prospective, single-arm, multicentre study. The primary end point was the procedural success rate. Major safety end points included major adverse cardiovascular events (MACE) and target lesion failure (TLF) at 30 days and 6 months, and severe angiographic complications. Calcification morphology was assessed in the optical coherence tomography (OCT) subgroup.

RESULTS

In total, 242 patients from 15 high-volume Chinese centres were enrolled, including 26.45% of patients with true bifurcation lesions, 3.31% with severely tortuous vessels, and 2.48% with chronic total occlusion, respectively. The procedural success rate was 95.04% (95% confidence interval 91.50%-97.41%), exceeding the prespecified performance goal of 83.4% (P < 0.001). The 30-day and 6-month MACE rates were 4.13% and 4.55%, respectively. TLF rates at those time points were 1.24% and 1.65%, respectively. Severe angiographic complications occurred in 0.42% of patients. In the OCT subgroup (n = 93), 93.55% of calcified lesions were fractured, and minimal lumen area increased from 1.55 ± 0.55 mm2 to 4.91 ± 1.22 mm2 after stent implantation, with acute gain rate of 245 ± 102%.

CONCLUSIONS

The novel intravascular lithotripsy system is effective and safe for managing severely calcified coronary lesions in a cohort that included true bifurcation lesions, severely tortuous vessels, and chronic total occlusion.

CLINICAL TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR), number ChiCTR2100052058.

Lifetime management of severely calcified coronary lesions: the treatment algorithm focused on the shape of calcification

The concept of lifetime management has not been discussed in the field of percutaneous coronary intervention (PCI), because the durability of drug-eluting stent (DES) is considered to be long enough for most patients. Furthermore, even if in-stent restenosis occurs, the treatment for in-stent restenosis is simple in most cases. On the other hand, the long-term clinical outcomes after DES implantation are worse in severely calcified coronary lesions than in non-calcified lesions. Moreover, the treatment for in-stent calcified restenosis or restenosis due to stent underexpansion is not simple. The concept of lifetime management of severely calcified lesions may be necessary like that of aortic stenosis. Recently, several algorithms have been published in PCI to severely calcified lesions, partly because of the emergence of IVL. These algorithms focus on the selection of cracking and debulking devices for the preparation of stenting. However, the optimal stent expansion does not guarantee the long-term patency, when the target lesion includes calcified nodules. Stent restenosis due to calcified nodules is difficult to manage. In this review article, we propose the algorithm for severely calcified lesions focused on the shape of calcification. We do not need to hesitate stenting when multiple cracks on circumferential calcification are observed by intravascular imaging devices. However, DCB may be an option as final device in some situations, when lifetime management of severely calcified lesions is considered.

The Role of Intracoronary Imaging for the Management of Calcified Lesions

Interventional cardiologists in everyday practice are often confronted with calcified coronary lesions indicated for percutaneous transluminal coronary angioplasty (PTCA). PTCA of calcified lesions is associated with diverse technical challenges resulting in suboptimal coronary stenting and adverse long-term clinical outcomes. Angiography itself offers limited information regarding coronary calcification, and the adjuvant use of intracoronary imaging such as intravascular ultrasound (IVUS) and Optical Coherence Tomography (OCT) can guide the treatment of calcified coronary lesions, optimizing the different stages of the procedure. This review offers a description of why, when, and how to use intracoronary imaging for PTCA of calcified coronary lesions in order to obtain the most favorable results. We used the PubMed and Google Scholar databases to search for relevant articles. Keywords were calcified coronary lesions, intracoronary imaging, IVUS, OCT, coronary calcium modification techniques, PTCA, and artificial intelligence in intracoronary imaging. A total of 192 articles were identified. Ninety-one were excluded because of repetitive or non-important information.

Balloon Catheter-Integrated Piezoelectric Micropyramid Arrays for Measuring Vascular Stiffness

Atherosclerosis is one of the severe cardiovascular diseases in which blood vessels lose elasticity and the lumen narrows. If atherosclerosis worsens, it commonly leads to acute coronary syndrome (ACS) due to the rupture of vulnerable plaque or aortic aneurysm. As the mechanical properties of vascular tissues vary from their conditions, measuring the vascular stiffness of an inner blood vessel wall may be applied to the accurate diagnosis of atherosclerotic symptoms. Therefore, early mechanical detection of vascular stiffness is highly needed for immediate medical attention for ACS. Even with conventional examination methods such as intravascular ultrasonography and optical coherence tomography, several limitations still remain that make it difficult to directly determine the mechanical properties of the vascular tissue. As piezoelectric materials convert mechanical energy to electricity without an external power source, a piezoelectric nanocomposite could be utilized as a balloon catheter-integrated mechanical sensor on its surface. Here, we present piezoelectric nanocomposite micropyramid balloon catheter (p-MPB) arrays for measuring vascular stiffness. We study the structural characterization and feasibility of p-MPB as endovascular sensors by conducting finite element method analyses. Also, multifaceted piezoelectric voltages are measured by compression/release tests, in vitro vascular phantom tests, and ex vivo porcine heart tests to confirm that the p-MPB sensor properly operates in blood vessels.

A study of balloon type on calcified coronary lesion predilation: A finite element analysis

Calcified coronary lesions have been one of the more difficult types of lesion for interventional treatment, and angioplasty is required to break the calcification before stent implantation so that the stent can expand smoothly, however, it remains unclear which type of angioplasty is optimal for different calcified lesions. In this study, a finite element approach was used to model normal balloons, cutting balloons, and AngioSculpt balloons. In addition, calcified lesions of different degrees, thicknesses, and lengths were modeled according to Intravascular ultrasound (IVUS) calcification grade. The above three balloons were used to pretreat calcified lesions, and the brittle fracture module for calcification was used to detect fracture success, to facilitate virtual stent implantation after predilation. The simulation results showed that with a thickness of less than 0.3 mm, balloons were unable to deal with calcified plaques in lesions of less than 120°, for 180° calcified lesions the cutting balloon fractured the calcified material at 1.2 MPa, the AngioSculpt balloon produced multiple fractures at 0.8 MPa for 270° calcified plaques, but was unable to fracture calcified lesions with a thickness of 0.4 mm. Based on these results, we conclude that the length of the lesion did not affect calcification fracture, while the thickness of the lesion did. In calcified lesions of approximately 180°, the cutting balloon showed the best predilation results, while the AngioSculpt balloon was optimal for 270°. In annular calcification, all three balloons were unable to fracture the lesion.

A prospective, multi-center, randomised controlled trial for evaluation of the effectiveness of the Blimp scoring balloon in lesions not crossable with a conventional balloon or microcatheter: the BLIMP study

BACKGROUND

Balloon uncrossable coronary lesions are lesions that cannot be crossed with a conventional balloon. Multiple balloons have been designed to overcome this problem. The Blimp balloon has a very low scoring profile (0.6 mm) with a very high rated burst pressure (30 atmospheres). We aimed to evaluate the efficacy of this balloon compared to customary low-profile balloons.

METHODS

We conducted a multicenter, prospective, randomised, controlled trial in which 126 patients with an uncrossable lesion were randomly (1:1 randomization) assigned to treatment first with the Blimp balloon or low-profile balloon. The primary endpoint was the success of crossing the lesion after initial failure with a microcatheter (group A) or with a conventional balloon (group B).

RESULTS

Overall, the first attempt of Blimp was successful in 29 out of 61 cases (48%) while the LP balloon immediately crossed in 30 out 67 cases (45%; p = 0.761). Using a low-profile balloon in the BLIMP group after failure of the Blimp balloon increased the success to 64% (39 out of 61 cases). Using the Blimp balloon in the low-profile first group after failure of the low-profile balloon increased the success to 60% (40 out of 67 cases). After the placement of a guide catheter extension, the overall successful lesion crossing in the BLIMP group was 80% (49 out of 61 cases) compared to 76% (51 out of 67 cases) in the LP Balloon group (p = 0.327).

CONCLUSIONS

The Blimp balloon catheter showed no superiority to customary low-profile balloons in uncrossable lesions. It can however be complementary in treating uncrossable lesions.

Contemporary Interventional Approach to Calcified Coronary Artery Disease

Calcific coronary artery disease is an increasingly prevalent entity in the catheterization laboratory which has implications for stenting and expected outcomes. With new interventional techniques and equipment, strategies to favorably modify coronary calcium prior to stenting continue to evolve. This paper sought to review the latest advances in the management of severe coronary artery calcification in the catheterization laboratory and discuss contemporary percutaneous interventional approaches.

Contemporary Management of Severely Calcified Coronary Lesions

Coronary artery calcification is increasingly prevalent in our patient population. It significantly limits the procedural success of percutaneous coronary intervention and is associated with a higher risk of adverse cardiovascular events both in the short-term and long-term. There are several modalities for modifying calcified plaque, such as balloon angioplasty (including specialty balloons), coronary atheroablative therapy (rotational, orbital, and laser atherectomy), and intravascular lithotripsy. We discuss each modality’s relative advantages and disadvantages and the data supporting their use. This review also highlights the importance of intravascular imaging to characterize coronary calcification and presents an algorithm to tailor the calcium modification therapy based on specific coronary lesion characteristics.

Combination therapy using scoring and sirolimus drug-coated balloons during lower limb endovascular revascularization for chronic limb threatening ischaemia: A case series

The aim of this case series was to document our early experience using combination therapy with UltraScore™ Focused Force percutaneous transluminal angioplasty balloon (BD Interventional, New Jersey, US) and Selution Sustained Limus Release (SLR)™ (M.A. MedAlliance SA, Nyon, Switzerland) sirolimus-coated balloon catheter for anti-restenotic drug elution, in the setting of multifocal high-grade stenosis for chronic limb threatening ischaemia. Our anecdotal experience was that preparing the lesion with scoring balloon and then using sirolimus drug-eluting balloon may have synergistic effect when used in tandem, especially in the setting of calcified arterial lesions, where the scoring wires may achieve deeper clefts within the atheromatous plaque to allow better drug absorption into the arterial wall. We report two cases with high-grade multifocal stenosis affecting the superficial femoral and anterior tibial arteries, respectively. Combination therapy using the scoring balloon to first prepare the lesion followed by sirolimus elution achieved technical and procedural success in both cases and a 100% 30-day primary patency. There were no complications related to flow-limiting dissections, vessel perforation or acute recoil. However, whether this combination therapy leads to better primary vessel patency with longer freedom from target lesion revascularization in the medium term remains to be determined.

Plaque modification in calcified chronic total occlusions: the PLACCTON study

INTRODUCTION AND OBJECTIVES

Severe calcification is present in> 50% of coronary chronic total occlusions (CTOs) undergoing percutaneous intervention. We aimed to describe the contemporary use and outcomes of plaque modification devices (PMDs) in this context.

METHODS

Patients were included in the prospective, consecutive Iberian CTO registry (32 centers in Spain and Portugal), from 2015 to 2020. Comparison was performed according to the use of PMDs.

RESULTS

Among 2235 patients, wire crossing was achieved in 1900 patients and PMDs were used in 134 patients (7%), requiring more than 1 PMD in 24 patients (1%). The selected PMDs were rotational atherectomy (35.1%), lithotripsy (5.2%), laser (11.2%), cutting/scoring balloons (27.6%), OPN balloons (2.9%), or a combination of PMDs (18%). PMDs were used in older patients, with greater cardiovascular burden, and higher Syntax and J-CTO scores. This greater complexity was associated with longer procedural time but similar total stent length (52 vs 57mm; P=.105). If the wire crossed, the procedural success rate was 87.2% but increased to 96.3% when PMDs were used (P=.001). Conversely, PMDs were not associated with a higher rate of procedural complications (3.7 vs 3.2%; P=.615). Despite the worse baseline profile, at 2 years of follow-up there were no differences in the survival rate (PMDs: 94.3% vs no-PMDs: 94.3%, respectively; P=.967).

CONCLUSIONS

Following successful wire crossing in CTOs, PMDs were used in 7% of the lesions with an increased success rate. Mid-term outcomes were comparable despite their worse baseline profile, suggesting that broader use of PMDs in this setting might have potential technical and prognostic benefits.

Verification of the differences of scoring effect in current scoring balloons

The characteristics of each scoring balloon seem to be different because material or configuration of scoring element in each device is unique. The aim of this study is to clarify the difference of scoring effect among 3 different scoring devices. We prepared 3 different scoring devices [Wolverine™ Cutting Balloon™ (CB), ScoreFlex™ NC (SF), NSE Alpha™ (NSE), n = 5 respectively. Balloon diameter is 3 mm and 2 types of silicone tubes with different elasticity [140 kPa (tube S) and 576 kPa (tube H), respectively. Inner diameter is 3 mm]. We dilated each balloon in each silicone tube with nominal pressure (NP) and 20 atmosphere (HP) and took a picture using a micro CT. We measured penetration depth of all scoring elements into silicone tube wall and calculated their percentage using the following formula; penetration depth/original scoring element height × 100. We also observed the deformation of scoring element during balloon inflation in each device. Scoring element of CB cut deeper into both tubes significantly than SF and NSE at both pressure (40.5% vs 25.1% and 16.8% at NP and 86.1% vs 33.5% and 29.1% at HP in tube S, p < 0.01, respectively, 62.6% vs 33.5% and 17.0% at NP and 93.3% vs 45.1% and 36.5% at HP in tube H, p < 0.01, respectively). Although no deformation of scoring element was recognized in CB, some deformations were observed in 50% of NSE and 40% of SF (p = 0.0377). Scoring balloon with sharp and firmly fixed scoring elements like CB may show definite scoring effect.

Predictive Factors of Severe Dissection after Balloon Angioplasty for Femoropopliteal Artery Disease

BACKGROUND

Arterial dissection is one of the mechanisms of balloon angioplasty. Although some degree of dissection is unavoidable, severe dissection that impedes blood flow decreases patency and increases the need for additional procedures. To improve the results of angioplasty, it is necessary to understand the factors related to severe dissection and make efforts to reduce its occurrence. This study aimed to elucidate the predictive and protective factors associated with severe dissection in femoropopliteal balloon angioplasty.

METHODS

This was a retrospective, single-center, nonrandomized study. A total of 409 limbs were studied in 334 patients with symptomatic femoropopliteal lesions treated between 2010 and 2019. Dissections after initial balloon angioplasty were classified according to the Kobayashi dissection classification (grade A: no dissection; B: mild dissection <1/3 of the lumen; C: severe dissection, ≥1/3 of the lumen) into the nonsevere dissection group (grades A and B), and severe dissection group (grade C). We compared clinical, procedural and lesion-related characteristics between the 2 groups. Factors with statistical significance in univariate analyses were entered into a multivariate logistic regression model to identify independent predictive factors of severe dissection.

RESULTS

Severe dissection occurred in 237 limbs and nonsevere dissection in 172 limbs. In univariate analyses, the predictive factors of severe dissection were TransAtlantic Inter-Society Consensus II C/D grades (P < 0.001), lesion length ≥15cm (P < 0.001), chronic total occlusion (P = 0.004), and degree of stenosis ≥70% (P < 0.001). Protective factors for severe dissection were end-stage renal disease (P = 0.008), severe calcification >50% (P < 0.001), and the use of a scoring balloon (P = 0.001). In multivariate analysis, factors associated with severe dissection were lesion length ≥15cm (OR, 2.259; 95% CI: 1.417-4-3.601), occlusion or degree of stenosis ≥70% (OR, 1.931; 95% CI: 1.255-2.971), severe calcification (OR, 0.520; 95% CI: 0.338-0.800), and the use of a scoring balloon (OR, 0.467; 95% CI: 0.263-0.830).

CONCLUSIONS

Lesion length ≥15cm and occlusion or stenosis ≥70% were identified as independent predictive factors of severe dissection in femoropopliteal artery balloon angioplasty. Conversely, severe calcification and the use of a scoring balloon appeared to be protective factors against severe dissection.

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.

The rotational atherectomy with a guide extension catheter for calcified and tortuous lesions in left anterior descending artery: a case report

Background

The interventional treatment of calcified lesions with severe tortuosity in the left anterior descending artery (LAD) was challenging and the report of rotational atherectomy with mother-and-child technique has been scarce.

Case presentation

An 84-year-old woman was hospitalized for non-ST-segment acute coronary syndrome. Coronary angiography revealed a calcified nodule in the LAD. During rotational atherectomy of the calcified and tortuous lesion in the proximal LAD, eccentric cutting due to wire bias nearly caused perforation. The burr seemed to protrude from the contrast media during angiography. Intravascular ultrasound imaging revealed that extremely eccentric ablation almost reached the adventitia. We successfully ablated the distal calcified nodule by preventing proximal overcutting of the tortuous lesion with support from a guide extension catheter, i.e., the mother-and-child technique, followed by the deployment of the drug-eluting stent. The patient was discharged without chest symptoms and no symptom recurred during 12-month follow-up.

Conclusion

This case demonstrated that safe ablation of a calcified nodule located distal to a tortuous and calcified lesion in the proximal LAD with the mother-and-child technique.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02167-3.

Novel preclinical method for evaluating the efficacy of a percutaneous treatment in human ex vivo calcified plaque

The lack of suitable atherosclerotic calcification models and testing strategies inhibits preclinical efficacy testing of existing and novel percutaneous devices. The goal of this study is to develop a preclinical testing method for quantitatively and qualitatively evaluating the efficacy of noncompliant balloon angioplasty (NC BA) treatment in human ex vivo calcified plaque (CP). NC BA using a 3- and 4-mm diameter balloon was performed on an ex vivo tibial calcified vessel obtained from an amputation. Three-dimensional microcomputed tomography (μ-CT) imaging was performed pre- and post-BA to compare crack density in the CP. Comparing the pre- and posttreatment three-dimensional μ-CT images showed a glass-like cracking that occurred in the CP due to the BA procedure. Expansion of the 3-mm balloon showed little tissue deformation and no CP cracking. Although expansion of the 4-mm balloon occurred nonuniformly along balloon length and across the perpendicular projections, the balloon generated cracking throughout the CP, which allowed the surrounding elastic tissue to be dilated. This combined X-ray microscopy and μ-CT technique is a useful preclinical tool for quantifying the efficacy of percutaneous treatments for CP. Because of its nondestructive nature, the CP structure can be visualized pre- and posttreatment to determine the treatment effect.

Efficacy of the Wolverine cutting balloon on a circumferential calcified coronary lesion: Bench test using a three-dimensional printer and computer simulation with the finite element method

Heavy calcification is one of the factors that hinder the success of coronary angioplasty, and a cutting balloon is used for such lesions. This study aimed to explore the optimal method of dilation of highly calcified lesions using a cutting balloon. Calcification models were developed from patient computed tomography and intravascular ultrasound data, and were constructed using three-dimensional printers. The lesions were dilated using a Wolverine™ cutting balloon and NC Emerge™ noncompliant balloon catheter, and the success rate of dilation and maximum dilation pressure were compared. The maximum first principal stresses in calcified lesions were also evaluated by computer simulation using the finite element method. In the bench test, the dilation success rate of the Wolverine™ cutting balloon was higher and the maximum dilation pressure required was lower (p < 0.01 in all analyses), compared with that of the NC Emerge™ balloon catheter. Finite element analysis showed that the cutting blade increased the maximum first principal stresses in calcified lesions, thus allowing for successful dilation at low pressures. The highest stress was obtained when the cutting blade was positioned at the thinnest part of the calcification. The cutting balloon allows for efficient calcification expansion by concentrating the stresses in the blade. When a cutting balloon is used, if the calcified lesion cannot be expanded in a single dilation, dilation success may be achieved after the balloon is rotated and the position of the blade is changed.

Breaking the deadlock of calcified coronary artery lesions: A contemporary review

Percutaneous coronary intervention (PCI) of severely calcified lesions is known to result in lower procedural success rates, higher complication rates, and worse long-term clinical outcomes compared to noncalcified lesions. Adequate lesion preparation through calcium modification is crucial in ensuring procedural success and reducing adverse cardiovascular outcomes. There are numerous calcium modification devices currently available whose usefulness depends on the nature of the calcific disease and its anatomical distribution. It can be challenging for the interventionists to decide which device is best suited for their patient. There is also emerging evidence for intravascular imaging in guiding selection of calcium modification devices using parameters such as calcium distribution and depth that directly impact on procedural success and clinical outcomes. In this review we aim to discuss the pathophysiology of coronary calcification, evaluate strategies and technologies of calcium modification and propose an A-M-A-S-A algorithm in managing calcified coronary lesions.

Management of Calcific Coronary Artery Lesions: Is it Time to Change Our Interventional Therapeutic Approach?

Patients with obstructive coronary lesions with a high calcium content (LHCC) have an exaggerated clinical risk, because the presence of calcification is associated with more extensive coronary atheroma and higher burden of comorbidities. Treatment of LHCC using percutaneous techniques is complex because of an increased risk of incomplete lesion preparation with suboptimal stent deployment and higher rates of acute and chronic stent failure. Rotational atherectomy has been the predominant technology for treatment of high-grade LHCC, but novel devices/technologies have entered clinical practice. It seems likely that combining enhanced intravascular imaging, which allows definition of the patterns of calcification with these new technologies, will herald a change in procedural algorithms for treatment of LHCC. This review provides an overview about LHCC with special focus on existing and emergent technologies. We also provide a proposed procedural algorithm to facilitate optimal use of technology according to specific features of LHCC and coronary anatomy.

Reinforcement of the anchor balloon system in percutaneous coronary intervention: an in vitro assessment

We evaluated the factors that increase the maximum static friction force between the anchoring balloon and the vessel wall. The anchor technique in percutaneous coronary intervention (PCI) may be better supported by a guiding catheter. However, in some cases, the anchor balloon does not perform optimally due to slippage within the anchoring vessel. Furthermore, the optimal procedure for balloon anchoring remains unknown. We evaluated the maximum static friction force of the anchor balloon via in vitro assessments using a simulated vessel model and coronary balloons. The simulated vessel model was composed of polytetrafluoroethylene, and its inner diameter was 1.5 mm. The various-sized balloons (diameter: 1.5 mm, 1.75 mm, and 2.0 mm; length: 10 mm and 15 mm) were inflated within the simulated vessel at various atmospheres. The maximum static friction force was measured by pulling on the balloon catheter shaft using 10-g weights. We performed the same experiment with a jailing 0.014″ wire under the anchoring balloon. Evaluated wires included a silicon coating coil wire, hydrophilic coating coil wire, polymer-coated non-tapering wire, and polymer-coated tapered wire. The maximum static friction force between the anchoring balloon and the simulated vessel increased with an increase in inflation pressure and balloon length. However, increasing the balloon diameter was not effective. The jailing 0.014″ wire, particularly coil wire, was effective in increasing the maximum static friction force of the anchor balloon. A longer balloon, higher inflation pressure, and jailing coil wire could reinforce the anchor balloon system.

Contemporary Approach to Heavily Calcified Coronary Lesions

Percutaneous treatment of heavily calcified coronary lesions still represents a challenge for interventional cardiology, with higher risk of immediate complications, late failure due to stent underexpansion and malapposition, and consequently poor clinical outcome. Good characterisation of calcium distribution with multimodal imaging is important to improve the successful treatment of these lesions. The use of traditional or new dedicated devices for the treatment of calcified lesions allows better lesion preparation; therefore, it is important that we know the different mechanisms and technical features of these devices.

Modular Catheter Systems in Minimally Invasive Interventional Medical Procedures: Case Study

Background

Medical device catheters that are used in minimally invasive interventional medical procedures all follow the same integrated design and use paradigm. The features and elements of any catheter device are combined in a single unitary construction. A modular approach to the design, construction, and use of these types of interventional catheters may provide significant advantages and benefits not available with an integrated design paradigm.

Objective

This paper aimed to present the design of a modular catheter system and the findings from an initial veterinary use as a case study for the potential of modular catheter systems in general.

Methods

A modular catheter system was designed using commercially available angioplasty balloon dilatation catheters as one module in the system and a custom designed scoring adapter as the other module. The scoring adapter incorporates wires to add scoring features to the angioplasty balloon catheter to improve the dilatation performance during a pulmonary valvuloplasty procedure. The scoring adapter also includes a novel attachment mechanism to couple the scoring adapter to any 0.035-inch guidewire–compatible angioplasty balloon catheter.

Results

The modular catheter system was successfully designed, manufactured, and used in an initial minimally invasive veterinary cardiovascular intervention to treat a case of canine subvalvular pulmonary stenosis. The scoring adapter and angioplasty balloon catheter were successfully combined tableside in the operating room at the time of the procedure and used to successfully dilate the subvalvular obstruction.

Conclusions

The successful design and use of the presented modular catheter system demonstrates the feasibility and potential advantages of this type of paradigm to enable physicians to create interventional catheter devices at the time of a procedure guided by the procedural needs.

Prognostic Impact of Scoring Balloon Angioplasty After Rotational Atherectomy in Heavily Calcified Lesions Using Second-Generation Drug-Eluting Stents: A Multicenter Registry-Based Study

BACKGROUND

We aimed to assess the impact of scoring balloon angioplasty (SBA) after rotational atherectomy (RA) on long-term clinical outcomes in patients who underwent percutaneous coronary intervention (PCI) using second-generation drug-eluting stents (DES). The long-term outcomes associated with SBA after RA in severely calcified lesions is unknown.

METHODS

Using the J2T ROTA registry data, we evaluated the clinical events of patients who underwent PCI using RA for heavily calcified lesions from January 2004 to December 2015. A total of 307 patients who underwent PCI with second-generation DES were analyzed and divided into the SBA (n = 96) and conventional balloon angioplasty (CBA) groups (n = 211). Eighty-two and 189 patients comprised the "SBA after small burr (SBA-SB)" and "CBA after small burr (CBA-SB)" subgroups, respectively, for the subgroup analysis. Study endpoints were incidence of 3-year major adverse cardiac events (MACE), target vessel revascularization (TVR), and target lesion revascularization (TLR).

RESULTS

Kaplan-Meier analysis revealed that the incidence of 3-year cumulative MACE, TVR, and TLR were comparable between groups, and that the incidences of 3-year cumulative MACE, TVR, and TLR were significantly lower in the SBA-SB subgroup than in the CBA-SB subgroup (log-rank p = 0.008; log-rank p = 0.047; log-rank p = 0.045; respectively). Multivariate Cox regression model indicated that SBA after RA was an independent predictor of MACE (hazard ratio: 0.337; 95% confidence interval: 0.139 to 0.817; p = 0.016).

CONCLUSIONS

Additional SBA following RA was associated with lower MACE incidence in patients undergoing RA with a small-sized burr.

Prolonged Inflation Technique Using a Scoring Balloon for Severe Calcified Lesion

Percutaneous coronary intervention for the treatment of a severe calcified lesion is still one of the most technically challenging areas of interventional cardiology. Calcified lesions are a cause of stent underexpansion, which significantly increases the subsequent risks of in-stent restenosis and thrombosis, even when drug-eluting stents are used. In this report, we describe the usefulness of prolonged inflations using a scoring balloon catheter (Scoreflex) for severe calcified lesions. Prolonged inflation using a scoring balloon enables an adequate dilation for treatment of a severe calcified plaque that was unresponsive to conventional technique with or without rotational atherectomy.

Towards the characterisation of carotid plaque tissue toughness: Linking mechanical properties to plaque composition

The morphological manifestation of calcification within an atherosclerotic plaque is diverse and the response to cutting balloon angioplasty remains an elusive target to predict in the presence of extensive calcification. This study examines the resistance of plaque tissue to blade penetration by characterising the underlying toughness properties and stratifying the upper and lower scale toughness limits based on the strong mechanical influence of calcification. Mechanical toughness properties of the common, bifurcation and internal carotid artery (n=62) were determined using guillotine-cutting tests measuring the energy required to pass a surgical blade through a unit length of plaque tissue. The corresponding structural composition of the dissected plaque segments was characterised using Fourier transform infrared analysis, electron microscopy and energy dispersive x-ray spectroscopy. Mechanical results reveal a clear distinction in toughness properties within each region of the carotid vessel with significantly tougher properties localised in the bifurcation (p=0.004) and internal region (p=0.0003) compared to the common. The severity of the intra-plaque variance is highest in plaques with high toughness localised in the bifurcation region (p<0.05). Structural examination reveals that the diverse mechanical influence of the level of calcification present is characteristic of specific regions within the carotid plaque. The energy required to overcome the calcific resistance and propagate a controlled cut in the calcified tissue at each region varies further with the degree of plaque progression. The identification of the localised calcification characteristics is a key determinant in achieving successful dissection of the severely toughened plaque segments during cutting balloon angioplasty.

STATEMENT OF SIGNIFICANCE

Calcification plays a fundamental role in plaque tissue mechanics and demonstrates a diverse range of material moduli properties. This work addresses the characterisation of the toughness properties in human carotid plaque tissue using a fracture mechanics approach. Toughness determines the energy required to propagate a controlled cut in the plaque material. This parameter is crucial for predicting the cutting forces required during endovascular cutting balloon angioplasty intervention. Results demonstrate that a strong relationship exists between the structural calcification configurations, fracture mechanisms and associated toughness properties that are characteristic of specific regions within the carotid artery plaque. The identification of the morphological characteristics of localised calcification may serve as a valuable quantitative measure for cutting balloon angioplasty treatment.

Treatment of calcified coronary artery lesions

Heavily calcified coronary plaques represent a complex lesion subset and a challenge to the interventional cardiologist, as they are often resistant to simple plaque modification with conventional balloon angioplasty. Inadequate plaque modification can lead to stent underdeployment, which itself predisposes to in-stent restenosis and stent thrombosis. Over the years, a number of mechanical devices ranging from modified angioplasty balloons to atherectomy devices have become available in order to tackle such lesions. Here we review these devices concentrating on the evidence behind their use.