Reduction of radiation exposure during complex interventions for chronic total coronary occlusions: Implementing low dose radiation protocols without affecting procedural success rates

Occupational Risks of Radiation Exposure to Cardiologists

PURPOSE OF REVIEW

Invasive cardiologists are exposed to large amounts of ionizing radiation. This review aims to summarize the main occupational risks in a radiation-exposed cardiology practice.

RECENT FINDINGS

We carried out a literature review on the subject. The studies reviewed allowed us to list six main health risk categories possibly associated with radiation exposure among cardiologists: deoxyribonucleic acid (DNA) and biochemical damages; cancers; ocular manifestations; olfaction, vascular, and neuropsychological alterations; musculoskeletal problems; and reproductive risks. Our descriptive analysis demonstrates higher risks of DNA damage and lens opacities among radiation-exposed cardiology staff. Surveys and questionnaires have demonstrated a higher risk of musculoskeletal disease in exposed workers. Studies reported no difference in cancer frequency between radiation-exposed workers and controls. Changes in olfactory performance, neuropsychological aspects, and vascular changes have also been reported. Limited literature supports the security of continuing radiation-exposed work during pregnancy. Therefore, there is an urgent need to increase knowledge of the occupational risks of radiation exposure and to adopt technologies to reduce them.

Anemia and periprocedural complications determine contrast-associated acute kidney injury after recanalization of chronic coronary occlusions in chronic kidney disease

BACKGROUND

Contrast-associated acute kidney injury (CA-AKI) is a potential risk associated with the percutaneous coronary interventions (PCI) for chronic total coronary occlusions (CTO) particularly with pre-existing chronic kidney disease (CKD). The determinants of CA-AKI in patients with pre-existing CKD in an era of advanced strategies of CTO recanalization techniques need to be considered for a risk evaluation of the procedure.

METHODS

A consecutive cohort of 2504 recanalization procedures for a CTO between 2013 and 2022 was analyzed. Of these, 514 (20.5%) were done in patients with CKD (estimated glomerular filtration rate < 60 ml/min based on the most recently used CKD Epidemiology Collaboration equation).

RESULTS

The rate of patients classified to have CKD would be lower with 14.2% using the Cockcroft-Gault equation, and 18.1% using the modified Modification of Diet in Renal Disease equation. The technical success was high with 94.9% and 96.8% (p = 0.04) between patients with and without CKD. The incidence of CA-AKI was 9.9% versus 4.3% (p < 0.001). The major determinants of CA-AKI in patients with CKD were the presence of diabetes and a reduced ejection fraction, as well as periprocedural blood loss, whereas a higher baseline hemoglobin and the use of the radial approach prevented CA-AKI.

CONCLUSIONS

In patients with CKD CTO PCI could be performed successfully at a higher cost of CA-AKI. Correcting preprocedural anemia and avoiding intraprocedural blood loss may reduce the incidence of CA-AKI.

First case report of fully robotically assisted lithotripsy in heavily calcified left main stenosis

Background

Percutaneous coronary intervention (PCI) is the standard-of-care treatment for left main stenosis as an alternative to bypass surgery. In addition, severe coronary lesion calcification can be modified by intravascular lithotripsy (IVL). However, with PCI and debulking treatment options, there are inherent limitations. PCI poses an increased health burden for the treating physician that is associated with wearing a heavy, lead-lined apron and being exposed to radiation. To overcome these issues, a robotically assisted angioplasty system (rPCI) was established that enables the operator to perform PCI remotely in routine clinical procedures. Furthermore, IVL have not been used remotely.

Case summary

Here, we report the use of this technique for treating a heavily calcified left main stenosis in an 82-year-old male with previously diagnosed two-vessel coronary artery disease, progressive symptoms of dyspnoea at high cardio-vascular risk profile. The decision of the local heart team declined surgery. To the best of our knowledge, this is the first report of successful rPCI combined with IVL.

Discussion

In the case presented, rPCI was feasible and safe even in a complex lesion of the left main coronary artery requiring IVL. rPCI is a revolutionary new technique that may be applied to various types of coronary artery lesions.

Recanalisation of coronary chronic total occlusions

Percutaneous treatment of coronary chronic total occlusions (CTO) has advanced greatly since its advent in the late 1970s through the development of dedicated wires and microcatheters, the improved skills of highly experienced operators and the adoption of new sophisticated strategies to guide procedural planning. The contemporary procedural success rate is 80-90% with a reduction in complications. Although there has been no improvement in prognosis in randomised trials to date, they, and other controlled registries of thousands of patients, confirm the pivotal role of CTO recanalisation in the treatment of angina and dyspnoea and an improvement in quality of life. Despite this evidence, CTO recanalisation is grossly underutilised. This review reports a detailed overview of the history, indications and treatment strategies for CTO recanalisation and hopes to increase interest among new, and especially young, operators in this demanding, rapidly evolving field of interventional cardiology.

On-line estimated peak skin dose during percutaneous coronary intervention for chronic total occlusion using new patient dose mapping technology

BACKGROUND

X-ray exposure during complex percutaneous coronary intervention is a very important issue.

AIM

To reduce patient peak skin dose during percutaneous coronary intervention procedures for chronic total occlusion using on-line estimated peak skin dose software (Dose Map).

METHODS

Throughout the procedure, Dose Map provided a map of local cumulative peak skin dose. This map was displayed in-room from 1Gy cumulative air kerma, and was updated every 0.5Gy. The operator's actions to minimize deterministic risks following map notification were collected. Skin reaction was evaluated 3 months after the procedure. A comparison with our historical X-ray exposure data (207 patients from January 2013 to July 2014) was performed.

RESULTS

From November 2015 to October 2016, 97 patients (Japanese chronic total occlusion score 2.1±1.1; 100 percutaneous coronary intervention procedures for chronic total occlusion) were prospectively enrolled. Fluoroscopy time was 40.8 (21.6-60.3) minutes, cumulative air kerma 1884 (1144-3231) mGy, estimated peak skin dose 962 (604-1474) mGy and kerma area product 115.8 (71.5-206.7) Gy.cm². Cumulative air kerma was>3Gy in 28% of cases, and>5Gy in 11% of cases. In 68% of cases, at least one action was taken by the operator after map notification to optimize skin dose distribution. Main changes included: gantry angulation (52%); field of view (25%); and collimation (13%). No skin injuries were observed at follow-up. In comparison with our chronic total occlusion historical radiation data, median cumulative air kerma and kerma area product were reduced by 31% and 33%, respectively (P<0.005.

CONCLUSION

Online skin dose mapping software allows the distribution of patient skin dose during complex percutaneous coronary intervention procedures, and may minimize X-ray exposure.

Chronic Total Occlusion Percutaneous Coronary Intervention in Patients With Prior Coronary Artery Bypass Graft: Current Evidence and Future Perspectives

Coronary chronic total occlusion (CTO), which occurs in 18. 4–52% of all patients referred for coronary angiography, represents one of the last barriers in coronary intervention. Approximately half of all patients with prior coronary artery bypass graft (CABG), who undergo coronary angiography, are diagnosed with coronary CTO. In fact, these patients often develop recurrent symptoms and events, necessitating revascularization. Currently, there is neither a consensus nor developed guidelines for the treatment of CTO patients with prior CABG, and the prognosis of these patients remains unknown. In this review, we discuss current evidence and future perspectives on CTO revascularization in patients with prior CABG, with special emphasis on clinical and lesion characteristics, procedural success rates, periprocedural complications, and long-term outcomes.

A prospective study on the incidence of contrast-associated acute kidney injury after recanalization of chronic total coronary occlusions with contemporary interventional techniques

BACKGROUND

Contrast-associated acute kidney injury (CA-AKI) is a potential risk associated with the percutaneous coronary interventions (PCI) for chronic total coronary occlusions (CTO). This study should evaluate the incidence of CA-AKI in an era of advanced strategies of recanalization techniques and identify modifiable determinants.

METHODS

We analysed 1924 consecutive CTO procedures in 1815 patients between 2012 and 2019. All patients were carefully monitored at least up to 48 h after a CTO procedure for changes in renal function.

RESULTS

The incidence of CA-AKI was 5.6%, but there was no relation to the technical approach such as frequency of the retrograde technique, intravascular ultrasound or radial access. Procedures with CA-AKI had longer fluoroscopy times (37.6 vs 46.1 min; p = 0.005). The major determinants of CA-AKI were age, presence of diabetes and reduced ejection fraction, as well as chronic kidney disease stage ≥2, serum haemoglobin, and fluoroscopy time. Contrast volume or contrast volume/GFR ratio were not independent determinants of CA-AKI. Periprocedural perforations were more frequent in CA-AKI patients (11.3 vs 2.3%; p < 0.001), and in-hospital mortality was higher (2.8 vs 0.4%; p < 0.001).

CONCLUSIONS

CA-AKI was associated with the risk of in-hospital adverse events. Established patient-related risk factors for CA-AKI (age, diabetes, preexisting chronic kidney disease, low ejection fraction) were confirmed in this study. In addition, the length of the procedure, coronary perforations and low preprocedural serum haemoglobin were risk factors that might be preventable in patients at high risk for CA-AKI.

The radioprotective effect of the Cathpax® AIR cabin during interventional cardiology procedures

BACKGROUND

The use of ionizing radiation during cardiac catheterization interventions adversely impacts the medical staff. Traditional radiation protection equipment is only partially effective. The Cathpax® radiation protection cabin (RPC) has proven to significantly reduce radiation exposure in electrophysiological and neuroradiology interventions. Our objective was to analyze whether the Cathpax® RPC reduces radiation dose in coronary and cardiac structural interventions in unselected real-world procedures.

METHODS AND RESULTS

In this nonrandomized all-comers prospective study, 119 consecutive cardiac interventional procedures were alternatively divided into two groups: the RPC group (n = 59) and the non-RPC group (n = 60). No significant changes in the characteristics of patients and procedures, average contrast volume, air kerma (AK), dose area-product (DAP) and fluoroscopy time between both groups were apparent. In the RPC group, the first-operator relative radiation exposure was reduced by 78% at the chest and by 70% at the wrist. This effect was consistent during different types of procedures including complex percutaneous interventions and structural procedures.

CONCLUSIONS

Our study demonstrates, for the first time, that the Cathpax® cabin significantly and efficiently reduces relative operator radiation exposure during different types of interventional procedures, confirming its feasibility in a real-world setting.

Reducing fluoroscopic and cineangiographic contribution to radiation exposure for chronic total coronary occlusion interventions

BACKGROUND

The treatment of chronic total coronary occlusions (CTO) carries the highest radiation exposure among percutaneous coronary interventions (PCI). In order to minimize radiation damage, we need to understand and optimize the contribution of all components of radiation exposure.

METHODS

A total of 1000 CTO procedures performed between 2011 and 2020 were compared according to implemented radiation modifications. Group 1 used the original set-up of the X-ray equipment (Artis Zee, Siemens). In group 2 a modified protocol aimed at reducing the fluoroscopy exposure, in group 3 further modifications aimed at reducing cineangiographic exposure.

RESULTS

Despite an increased lesion complexity, Air Kerma (AK) was reduced from 2619 mGy (1653-4574) in group 1 to 2178 mGy (1332-3500; p < 0.001) in group 2 by mainly reducing fluoroscopic contribution by 54.1%, the cineangiographic contribution was lowered by only 6.6%. In group 3 AK dropped drastically to 746 mGy (480-1225; p < 0.001) mainly by reducing the cineangiographic contribution by 53.4%, still there was a further reduction of fluoroscopy contribution of 8.2%. This also led to a reduction of the skin entry dose from 1038 mGy (690-1589) in group 2 to 359 mGy (204-591; p < 0.001) in group 3. This was achieved both in normal weight and obese patients, and both in antegrade and retrograde procedures.

CONCLUSIONS

The present study demonstrates that by modifying both the fluoroscopic and cineangiographic contribution to radiation exposure a drastic reduction of radiation risk can be achieved, even in obese patients. Currently accepted radiation thresholds may no longer be a limit for CTO PCI.

Radiation Safety Performance is More than Simply Measuring Doses! Development of a Radiation Safety Rating Scale

PURPOSE

Radiation safety performance is often evaluated using dose parameters measured by personal dosimeters and/or the C-arm, which provide limited information about teams' actual radiation safety behaviors. This study aimed to develop a rating scale to evaluate team radiation safety behaviors more accurately and investigate its reliability.

MATERIALS AND METHODS

A modified Delphi consensus was organized involving European vascular surgeons (VS), interventional radiologists, and interventional cardiologists. Initial items and anchors were drafted a priori and rated using five-point Likert scales. Participants could suggest additional items or adjustments. Consensus was defined as ≥ 80% agreement (rating ≥ 4) with Cronbach's alpha ≥ .80. Two VS with expertise in radiation safety evaluated 15 video-recorded endovascular repairs of infrarenal aortic aneurysms (EVAR) to assess usability, inter and intrarater reliability.

RESULTS

Thirty-one of 46 invited specialists completed three rating rounds to generate the final rating scale. Five items underwent major adjustments. In the final round, consensus was achieved for all items (alpha = .804; agreement > 87%): 'Pre-procedural planning', 'Preparation in angiosuite/operating room', 'Shielding equipment', 'Personal protective equipment', 'Position of operator/team', 'Radiation usage awareness', 'C-arm handling', 'Adjusting image quality', 'Additional dose reducing functions', 'Communication/leadership', and 'Overall radiation performance and ALARA principle'. All EVARs were rated, yielding excellent Cronbach's alpha (.877) with acceptable interrater and excellent intrarater reliability (ICC = .782; ICC = .963, respectively).

CONCLUSION

A reliable framework was developed to assess radiation safety behaviors in endovascular practice and provide teams with formative feedback. The final scale is provided in this publication.

In-Hospital Outcomes After Recanalization of Ostial Chronic Total Occlusions

BACKGROUND

Percutaneous coronary intervention (PCI) of chronic total occlusion (CTO) still remains a major challenge in interventional cardiology. Recanalization of ostial lesions is challenging and complex. This present study aims to evaluate the outcome of patients with ostial and non-ostial CTO-PCI with regard to acute, in-hospital outcome.

METHODS

Between 2012 and 2018 we included 600 patients. Ostial lesions (OL) were defined as a coronary arterial stenosis within 3 mm of the vessel origin. Antegrade and retrograde CTO-PCI techniques were used and a composite safety endpoint comprising in-hospital death, vascular complications, cardiac tamponade, stroke and acute myocardial infarction.

RESULTS

The majority of the patients were male (82.3%) and the mean age was 62.1 years (±10.3 years). The right coronary artery (RCA) was the most frequent target vessel in 58.5%, followed by the left circumflex artery (LCX) (15.4%) and the left anterior descending artery (LAD) (26.2%). The success (p = .439) and complication rates (p = .169) were independent of the target vessel. We determined that examination and fluoroscopy time were longer in patients with OL (120.7 min vs. 99.0 min, p < .001 and 44.9 min vs. 34.5 min, p < .001) and that in this group of patients the retrograde approach was used more frequent (38.8% vs. 18.2%, p < .001). Overall success rates were lower in OL than compared to NOL (74.6% vs. 86.5%, p = .016).

CONCLUSIONS

Our retrospective study suggests that recanalization of ostial CTO lesions is associated with reduced PCI success rates as well as long examination and high fluoroscopy times.

Reduction of radiation exposure to operating physician and assistant using a real-time auditory feedback dosimeter during femoral artery puncturing: a study on swine model

Background

Real-time dosimeters may create a relatively safer environment not only for the patient but also for the physician and the assistant as well. We propose the use of a real-time radiation measurement dosimeter having auditory feedback to reduce radiation exposure.

Methods

Radiation dose rates were measured for 30 fluoroscopy-guided puncturing procedures of femoral arteries in swine. Fifteen puncturing procedures were performed with real-time radiation measurement dosimeter having auditory feedback and other 15 were performed without auditory feedback dosimeter by an interventional cardiologist with 10 years of experience.

Results

The left body side of the operating physician (38%, p < 0.001) and assistant (25%, p < 0.001) was more exposed as compared to the right body side. Radiation dose rate to the left hand, left arm and left leg were reduced from 0.96 ± 0.10 to 0.79 ± 0.12 mSv/h (17% reduction, p < 0.001), from 0.11 ± 0.02 to 0.07 ± 0.01 mSv/h (36% reduction, p < 0.001) and from 0.22 ± 0.06 to 0.15 ± 0.02 mSv/h (31% reduction, p < 0.001) with the use of auditory feedback dosimeter, respectively. The mean fluoroscopic time was reduced from 4.8 ± 0.43 min to 4.2 ± 0.53 min (p < 0.001). The success rate of performing arterial puncturing was 100%.

Conclusions

The use of auditory feedback dosimeter resulted in reduction in effective dose. The sound beep alerted the physician from the danger of exposure, and this approach induced awareness and protective mindset to the operating physician and assistant.

Reduction of operator radiation exposure using a passive robotic device during fluoroscopy-guided arterial puncture: an experimental study in a swine model

Background

Vascular interventions imply radiation exposure to the operating physician (OP). To reduce radiation exposure, we propose a novel passive robotic device for fluoroscopy-guided arterial puncturing.

Methods

X-ray dose rates were measured for a total of 30 fluoroscopy-guided puncture femoral arteries in 15 pigs. Fifteen punctures were performed with the device while the other 15 were performed without the device by an interventional cardiologist with 10 years of experience. Parametric t test was used.

Results

The success rate with the device was 100%. Overall, the OP received more radiation (0.41 mSv/h) as compared to the assistant (0.06 mSv/h) (p <  0.001) and, amongst OP’s body parts, hands received more radiation than other body parts (p <  0.001). The radiation dose rate to the OP’s hands during arterial puncturing performed manually without the device was 0.95 ± 0.25 mSv/h whereas it was 0.14 ± 0.006 mSv/h using the device, resulting in an 85% reduction (p <  0.001). For the head, the dose was reduced from 0.16 mSv/h to 0.08 mSv/h (50% reduction, p <  0.001), and for the dominant arm, from 0.12 mSv/h to 0.07 mSv/h (42% reduction, p <  0.001). The fluoroscopy time was reduced from 4.5 ± 0.15 min to 4.3 ± 0.11 min device (p = 0.002).

Conclusions

In a swine model, fluoroscopy time and radiation exposure for the OP puncturing femoral artery were significantly reduced by using the passive robotic device.

Chronic Total Occlusion Interventions: Update on Current Tips and Tricks

PURPOSE OF REVIEW

To summarize novel techniques and developments in chronic total occlusion (CTO) percutaneous coronary intervention (PCI).

RECENT FINDINGS

Using an algorithmic, step-by-step approach can help overcome several complex CTO lesions subsets, such as proximal cap ambiguity, ostial location, in-stent occlusion, bifurcations, balloon uncrossable and undilatable lesions. Similarly, an algorithmic approach can help prevent and optimally treat CTO PCI-related complication, such as perforation, radiation, and contrast-induced nephropathy. Continual update and reassessment of each operator's algorithm for performing CTO PCI can lead to improved outcomes.

Safety and feasibility of a low frame rate protocol for percutaneous coronary intervention to chronic total occlusions: preliminary experience

AIMS

The present study aimed to evaluate the safety and feasibility of a low frame rate protocol for chronic total occlusion (CTO)-percutaneous coronary intervention (PCI).

METHODS AND RESULTS

A total of 192 consecutive patients who underwent CTO-PCI following the low frame rate protocol were analysed. The low frame rate protocol adopted reduced frame rates and the addition of copper and aluminium filters. Procedural outcomes, radiation dose and in-hospital outcomes were ascertained. Meanwhile, a phantom experiment was designed to measure the radiation dose reduction. Overall technical and procedural success rates were 91.1% (175) and 90.6% (174), respectively. The retrograde approach was attempted in 56 (29.2%) lesions. The mean air kerma (AK) radiation exposure, fluoroscopy time and contrast volume were 2.6±2.0 Gy, 50.3±34.3 min and 294.1±131.8 ml, respectively. In-hospital major adverse events occurred in one patient (0.5%) and procedural complications occurred in six patients (3.1%). In the phantom experiment, a remarkable radiation dose reduction could be achieved for AK, dose area product (DAP), simulated first and second operator radiation exposure (reduction of 72.5%, 69.8%, 60.9% and 59.6%, respectively) in cineangiography from this protocol.

CONCLUSIONS

Our results provide the primary evidence that it appears to be safe and feasible to carry out the low frame rate protocol for CTO-PCI.