Figura 1. Radial artery ultrasound images from study subjects: A) Cross-sectional measurement of rad...

Figura 2. Spectral Doppler of the radial artery: A) Normal triphasic flow, with systolic flow (a), d...

Tabla 1. Baseline population characteristic

Tabla 2. Ultrasound-measured radial artery characteristics

Figura 3. Procedural complications. Of note, there were no complications in most cases (81.48%), whi...

Tabla 3. Ultrasound-measured radial artery characteristics and procedural success.

Figura 4. Procedural complications. Of note, there were no complications in most cases (81.48%), whi...

Introduction

Transradial access has been associated with numerous benefits in coronary angioplasty compared to femoral access, such as lower mortality at 30 days and 1 year, which could be related to a reduced incidence of vascular complications1 and a lower risk of hematoma (3.7% vs. 1.4%)2, 3. Complications related to arterial access techniques include arterial spasm, bleeding, hematoma, pseudoaneurysm, arterial dissection, arterial thrombosis, embolism, and perforation4.

In 1996, Fernando Kiemeneij pioneered the transradial approach, which has increased procedural success rates, improved patient comorbidity outcomes, and favored better hemostasis5. Today, compared to palpation, ultrasound-guided transradial artery access has proven to reduce bleeding complications, decrease incidental venipunctures, and improve first-attempt success rates. The most commonly used ultrasound views include the short-axis view (for anatomical visualization) and the long-axis view (for needle tip visualization) with dynamic needle tip positioning6.

The use of Doppler ultrasound to guide transradial access has been established as a crucial technique for minimizing failed attempts and facilitating access in patients with challenging conditions such as obesity, edema, small-diameter arteries, or hypotension6-8. The effectiveness of this method for the improvement of transradial access success rates and the reduction of associated complications is well-documented6, 8. In our study, we explore this notion in greater depth by investigating by means of ultrasound various radial artery characteristics, including diameter, tortuosity, and flow patterns, to determine their contribution to procedural success. This allows us to propose more effective strategies for patient selection, ultimately optimizing clinical outcomes. To achieve this goal, we designed this cohort study to identify ultrasound characteristics that predict both success and potential complications in percutaneous coronary interventions.

Materials and methods

This prospective cross-sectional study included patients from June 2022 to December 2023. Using Doppler ultrasound of the right radial artery, we measured the diameter, anatomical characteristics (calcification and tortuosity), velocities, and flow waveforms. Informed consent was obtained.

Vascular access for percutaneous coronary intervention (PCI) was performed using the Seldinger technique by physicians fully specialized in hemodynamics with interventional cardiology training in a fellowship program. In all cases, a 6-Fr introducer was used. The Doppler ultrasound examination was conducted by experienced specialists in peripheral ultrasound, training physicians and cardiology residents, under the direct supervision of trained specialists. Images were obtained using a Sonoscape X3 ultrasound system, available at the Coronary Unit of Clínica Santa Clara de Quilmes. No external funding was used for this study.

The sample size was determined based on convenience and it included consecutive patients treated during the study period. This approach allowed for the collection of data representative of daily clinical practice. However, it is also acknowledged as a limitation regarding result generalization.

Dependent variable. Success of transradial access for PCI. It was defined as procedural completion without complications related to the transradial access, including absence of arterial spasm, hematoma, pseudoaneurysm, arterial dissection, thrombosis, embolism, or perforation. Based on this criterion, patients were classified into two groups (successful and unsuccessful) for comparison of the independent variables.

Independent variables. Radial artery characteristics assessed by ultrasound. These include diameter, calcification, tortuosity, velocity, and flow waveforms. Each of these characteristics was evaluated using a 5-10 MHz linear transducer in B-mode, color, and spectral mode.

Radial artery diameter. It was measured in centimeters at the proximal crease of the wrist. The normal cross-sectional diameter of the radial artery as measured by eco-Doppler is 0.24 cm (0.22-0.28), and the peak systolic flow velocity (PSV) is 48 cm/s (39-75 cm/s)9.

Tortuosity. It is defined as a curvature greater than 45º over the course of the artery. At the radial artery, its incidence is between 2% and 6%.

Wall calcification. This was Identified by the presence of echogenic areas on the anterior or posterior artery walls10.

Flow waveform type. It could be classified as triphasic, biphasic, or monophasic. In the upper limbs, the normal pulsatile flow pattern is triphasic11.

Figure 1 presents these ultrasound findings for the study subjects, showing the ultrasound measurement of the diameter, its representation of arterial tortuosity, and the characterization of calcification. Figure 2 details the flow waveform type.

Population. Patients aged 18 years or older, diagnosed with ACS and undergoing PCI at the Coronary Unit of Clínica Santa Clara de Quilmes after spontaneous consultation or referral from partner institutions, who agreed to participate in the study.

Aims. Assessing the association between ultrasound-measured radial artery characteristics, including diameter, flow velocity, flow waveform pattern, calcification, and tortuosity, and PCI success in patients with ACS. The study aims to identify ultrasound parameters that serve as predictors of successful transradial access, in order to optimize patient selection for this approach and improve clinical outcomes.

Inclusion criteria.

• Age: 18 years or older.

• Diagnosis: ACS.

• Location: admitted to Clínica Santa Clara de Quilmes.

• Treatment: need for emergency PCI or PCI during hospitalization.

• Consent: explicit agreement to participate in the study.

Exclusion criteria.

• Medical history. Patients with a history of myocardial revascularization surgery (MRS) were excluded for two main reasons: the possible use of the radial artery as a graft, and the lack of detailed information or documentation regarding the coronary bypass performed, which created uncertainty about patient vascular anatomy.

• Impossibility to puncture the radial artery for any reason.

• Clinical status: after cardiac arrest.

• Patients with hemodialysis through an arteriovenous fistula on the side proposed for access.

Statistics

The data were analyzed using descriptive and inferential statistics. Central tendency and dispersion measures were used for quantitative variables, while frequency and percentages were used for qualitative variables. Ultrasound-measured radial artery characteristics were compared between patients with successful and unsuccessful transradial access for PCI using Student’s t-tests and Chi-square tests, depending on variable distribution. Logistic regression analyses were performed to identify predictors of successful transradial access. The statistical data, as well as the graphs, were analyzed and created with the SPSS Statistic v25 software.

Results

The study included a total of 108 patients, of whom 66.7% were men. The average participant age was 71.69 years. The most frequent comorbidities included hypertension (81.5%), diabetes mellitus (30.6%), dyslipidemia (41.7%), and chronic kidney disease (11.1%). Patients mostly presented with non-ST segment elevation ACS without ST elevation (NSTEACS, 64.8%) and ST-segment elevation acute myocardial infarction (STEMI, 35.2%) (Table 1).

Regarding local complications after the procedure, there were no complications in most cases (81.48%). Arterial spasm was reported in 11.11% of patients, and cannulation difficulties or transradial access failure and hematoma were each reported in 3.70% of cases (Figure 3). There were no statistically significant differences in the average diameter of the radial artery between patients with successful (0.29±0.40) and unsuccessful (0.27±0.34) procedures, with a p-value of 0.501. This finding suggests that arterial diameter, by itself, may not be a decisive predictor of successful transradial access. There were no statistically significant differences regarding tortuosity and arterial calcification in relation to procedural outcomes.

Regarding ultrasound-measured radial artery characteristics, compared to the mean diameter of the radial artery, men had a larger diameter (0.30±0.03) compared to women (0.27±0.04). There were no significant differences in average peak systolic velocity (PSV) between men (33.35±15.14 cm/s) and women (35.42±13.9 cm/s). Tortuosity was present in 7.4% of cases, and it was more frequent in women (8.3%) than in men (6.9%). Calcification was present in 6.5% of patients. Regarding the arterial flow waveform, most subjects presented a triphasic pattern (71.3%), which was slightly more common in men (72.2%) than in women (69.4%).

A biphasic pattern was observed in 24.1% of participants, with similar percentages between men (25.0%) and women (22.2%). The monophasic pattern was the least common (4.6%) and it was considerably more frequent in women (8.3%) compared to men (2.8%) (Table 2).

Table 3 presents the ultrasound-measured radial artery characteristics. Of note, the average artery diameter did not differ significantly between successful (29.05±4.07 mm) and unsuccessful procedures (27.27±3.47 mm), with a p-value of 0.501. There were no statistically significant differences in the incidence of tortuosity and calcification in relation to procedural outcomes (p-values of 0.345 and 0.975, respectively). However, a statistically significant correlation was identified between procedural success and the presence of a triphasic flow waveform, found in 79.6% of all successful cases compared to 20% of unsuccessful ones, with a substantial effect size of 0.596 and a 95% confidence interval for successful cases from 71.4% to 87.8% (p < 0.001) (Figure 4). This finding highlights the triphasic flow waveform pattern as a potential predictor of success in procedures related to radial puncture.

Discussion and limitations

This study deepens our understanding of how ultrasound-measured radial artery characteristics can impact PCI success in patients with ACS. Previous research has highlighted transradial access as more favorable than femoral access due to lower complication and mortality rates12-14. However, there is limited knowledge regarding which specific radial artery characteristics predispose to success or failure. A detailed assessment of radial artery anatomy by means of ultrasound before interventions allowed for the identification of patients at high risk for complications or access failure (tortuosity, stenosis, hypoplasia, radioulnar loops), thus improving clinical outcomes and reducing risks associated with PCI15.

While our study did not find a significant association between radial artery diameter and access success (p = 0.501), previous studies, such as the meta-analysis by Moussa Pacha et al.6, suggest that a smaller diameter may complicate access, especially in the absence of ultrasound guidance. However, routine use of Doppler ultrasound in our cohort may have mitigated these difficulties, favoring success rates even in smaller-caliber arteries. Additionally, research such as that by Yokoyama et al.15 emphasizes that other anatomical factors, like tortuosity or loops, could have a greater impact on access success. These findings underscore the importance of comprehensive ultrasound assessment beyond diameter measurement.

Our study identified a triphasic flow pattern in the radial artery as a significant predictor of access success, providing a basis for a more personalized approach in access site selection.

The results of this study have important implications for clinical practice. Doppler ultrasound of the radial artery can be a useful tool to identify patients with a higher likelihood of successful transradial access for PCI. This information can help physicians select the most appropriate vascular access for each patient.

Doppler ultrasound allows for a non-invasive identification of favorable radial artery characteristics to improve access outcomes. Our findings suggest that the implementation of imaging protocols before the procedure could be an effective strategy to enhance procedural safety and efficacy.

Multicenter studies and randomized controlled trials are needed to validate and expand our results. Future research should focus on the impact of triphasic arterial flow and other ultrasound characteristics on a broader range of endovascular procedures, as well as the development of access protocols based on individual characteristics.

Skill in puncture and ultrasound use are essential for successful transradial access. Training and certification in these skills should be included in all training programs for operators.

Limitations

The observational design of this study and the fact that it was conducted at a single center limit the generalization of these results. Additionally, while there was a significant correlation between certain ultrasound characteristics and transradial access success, causality has not been established. It is essential that these limitations be addressed through studies with a more representative sample and a design that allows for causal inferences.

Reliance on specific Doppler ultrasound technology, which is not universally accessible, may limit the applicability of this technique.

Conclusions

The results showed that, of all ultrasound-measured radial artery characteristics, the presence of triphasic flow, specifically, was significantly associated with transradial access success for PCI. This finding supports the integration of this imaging technique as a pre-PCI assessment, facilitating better access site selection. Future research is needed to confirm these results in various clinical settings and refine access protocols for PCI.

This study supports the routine use of radial Doppler ultrasound as a pre-PCI assessment tool, especially in patients with complex anatomy. The increasing availability of Doppler equipment in departments of hemodynamics and other cardiovascular care units facilitates its implementation, so we recommend its integration into clinical practice and inclusion in clinical and interventional cardiology training programs to optimize outcomes.

Summary of key points

Current knowledge. The effectiveness of transradial access in coronary interventions is well known, but the influence of ultrasound-measured radial artery characteristics on procedural success remains uncertain.

Key findings. This study confirms that triphasic flow in the radial artery, assessed by Doppler ultrasound, significantly predicts the success of percutaneous coronary interventions.

1. Chase AJ, Fretz EB, Warburton WP, et al. Association of the arterial access site at angioplasty with transfusion and mortality: the M.O.R.T.A.L. study (Mortality benefit Of Reduced Transfusion after percutaneous coronary intervention via the Arm or Leg). Heart. 2008 Aug;94(8):1019-25. doi: 10.1136/hrt.2007.136390. Epub 2008 Mar 10.

2. Jolly SS, Yusuf S, Cairns J, et al. Radial versus femoral access for coronary angiography and intervention in patients with acute coronary syndromes (RIVAL): a randomised, parallel group, multicentre trial. Lancet. 2011 Apr 23;377(9775):1409-20. doi: 10.1016/S0140-6736(11)60404-2. Epub 2011 Apr 4. Erratum in: Lancet. 2011 Apr 23;377(9775):1408. Erratum in: Lancet. 2011 Jul 2;378(9785):30. .

3. Vranckx P, Frigoli E, Rothenbühler M, et al. Radial versus femoral access in patients with acute coronary syndromes with or without ST-segment elevation. Eur Heart J. 2017 Apr 7;38(14):1069-1080. doi: 10.1093/eurheartj/ehx048.

4. Rao SV, Cohen MG, Kandzari DE, et al. The Transradial Approach to Percutaneous Coronary Intervention. J Am Coll Cardiol. 2010;55(20):2187–2195. doi:10.1016/j.jacc.2010.01.039.

5. Kiemeneij F, Laarman GJ. Percutaneous transradial artery approach for coronary Palmaz-Schatz stent implantation. Am Heart J. 1994;128(1):167–174. doi:10.1016/0002-8703(94)90023-x.

6. Moussa Pacha H, Alahdab F, Al-Khadra Y, et al. Ultrasound-guided versus palpation-guided radial artery catheterization in adult population: A systematic review and meta-analysis of randomized controlled trials. Am Heart J. 2018 Oct;204:1-8. doi: 10.1016/j.ahj.2018.06.007. Epub 2018 Jun 19. .

7. Aragoncillo I, Caldés Ruisanchez S. Ecografía Doppler en el Acceso Vascular. Nefrología al día. Disponible en: https://www.nefrologiaaldia.org/291.

8. Miller AG, Cappiello JL, Gentile MA, et al. Analysis of radial artery catheter placement by respiratory therapists using ultrasound guidance. Respir Care. 2014 Dec;59(12):1813-6. doi: 10.4187/respcare.02905. Epub 2014 Jul 15.

9. Coderech Carretero J, Corella Montoya F, Grande Barez M, et al. Descripción y análisis del patrón de normalidad de flujo dinámico y morfológico de las arterias principales de la muñeca y mano en población sana española. Rev Esp Cir Ortop Traumatol. 2020;64(3):167-176. doi:10.1016/j.recot.2019.12.004.

10. Coroleu SF, Burzotta F, Trani C, et al. Manejo de variantes anatómicas complejas del acceso radial en la realización de procedimientos coronarios. Rev Esp Cardiol. 2021;74(5):27-31.

11. Titievsky LC, Mosso GF, García Mallea G, et al. Guías de práctica de Eco Doppler Vascular 2022. Rev Fed Arg Cardiol. 2022;51(Suplemento 4):7-62.

12. Elízaga Corrales J. Acceso por vía radial: ¿debería ser más utilizado? Rev Esp Cardiol. 2003;56(2):124-7.

13. García-Rueda KA, Cediel-Barrera CH, Plaza-Tenorio M, et al. Incidencia, impacto funcional y factores predictores para la presentación de complicaciones asociadas al acceso radial para Coronariografía evaluadas por medio de ultrasonografía, cohorte hospitalaria. Arch Cardiol Mex. 2022;92(2):230-241.

14. Sandoval Y, Bell MR, Gulati R. Transradial artery access complications. CircCardiovascInterv. 2019;12:e007386. doi: 10.1161/circinterventions.119.007386.

15. Yokoyama N, Takeshita S, Ochiai M, et al. Anatomic variations of the radial artery in patients undergoing transradial coronary intervention. Catheter CardiovascInterv. 2000;49(3):357-362.

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Triphasic flow as a predictor of success in transradial access for coronary angioplasty: a prospective study with Doppler ultrasound

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