Transradial Approach of Alcohol Septal Ablation Using a Sheathless Guiding Catheter: A Feasibility Study

Abstract: Objectives. We aimed to investigate the feasibility and safety of alcohol septal ablation (ASA) via transradial approach using a sheathless guiding catheter. Background. Although ASA is conventionally performed via the femoral artery, there is a potential risk of bleeding and other vascular complications. The transradial approach may be associated with a lower rate of such complications. A sheathless guiding catheter, with an advanced hydrophilic coating along its full length, could reduce radial artery occlusion and spasm. Methods. We enrolled 14 consecutive patients with hypertrophic obstructive cardiomyopathy treated with ASA via the radial access at Sendai Kousei Hospital from December 2012 to May 2014. Left radial access was used for the sheathless guiding catheter, while right radial access was used for monitoring left ventricular pressure with a 4 Fr diagnostic catheter. A temporary pacemaker was inserted via the right jugular vein. Results. Procedural success rate was 93% (13/14 patients). The left ventricular outflow tract pressure gradient at rest was reduced from a median of 128 mm Hg (interquartile range, 49-147 mm Hg) at baseline to a median of 16 mm Hg (interquartile range, 13-26 mm Hg) at 30-day follow-up (P=.01). The New York Heart Association functional class improved from a median of II (II–III) at baseline to a median of I (I–I) at 30-day follow-up (P=.01). There were no cases of access-site complication, including radial artery occlusion and spasm. Conclusions. The transradial approach using a sheathless guiding catheter was feasible and safe for ASA.

J INVASIVE CARDIOL 2015;27(11):E242-E247

Key words: alcohol septal ablation, sheathless guide, radial access

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Patients with hypertrophic obstructive cardiomyopathy (HOCM) have high morbidity and mortality.¹ Ventricular septal myectomy is the standard operative intervention for patients with severe drug-refractory symptoms. Alcohol septal ablation (ASA), performed using a transcatheter therapeutic procedure, is an alternative to surgery.² In the 2011 American College of Cardiology Foundation/American Heart Association (ACCF/AHA) guidelines, ASA is preferred in patients for whom surgical septal myectomy is considered high risk, particularly in the elderly.³

The transfemoral approach has a potential risk for bleeding complications. The mortality of patients with femoral access was higher vs those with radial access due to increased transfusion rates.⁴

Radial access may also be advantageous for ASA; however, transradial ASA has limitations. It may cause radial spasm. The vasodilators for preventing spasm, such as nitroglycerin, are unfavorable because they may worsen outflow tract obstruction. Moreover, the transradial approach is also limited by the radial artery size. The development of the sheathless guiding catheter (Sheathless Eaucath; Asahi Intecc) has eliminated the need for a traditional sheath.⁵ The outer diameter of a sheathless guiding catheter, which has an inner lumen similar to a conventional guiding catheter, is approximately 2 Fr smaller than a conventional guide catheter. Furthermore, the hydrophilic coating has a preventive effect against radial artery spasm.⁶ The potential efficacy of sheathless guiding catheters in the setting of ASA remains to be evaluated. This is a prospective, descriptive, single-center cohort study to investigate the feasibility and safety of ASA via transradial approach using a 6.5 Fr or 7.5 Fr sheathless guiding catheter. 

Methods

Patient selection. During the period of this study, a total of 14 symptomatic HOCM patients, despite optimal medical treatment, visited Sendai Kousei Hospital who were candidates for ASA or septal myectomy surgery. Because surgery was available at our institute, we presented treatment options (ASA or surgery) for these patients. Considering the patients’ advanced age, ASA was chosen in all of the candidates for invasive therapy, in spite of the higher risk of permanent pacemaker implantation. Therefore, we prospectively included 14 consecutive patients from our institute from December 2012 to May 2014, treated with ASA via the radial access with symptomatic HOCM despite optimal medical treatment (New York Heart Association [NYHA] functional class II to IV). The primary indication for ASA consisted of drug-refractory symptoms with NYHA functional class III-IV. Even if patients were in NYHA class II, patients with syncope or presyncope were also considered for ASA. Because of selection in accordance with the ACCF/AHA guidelines, all subjects demonstrated a dynamic left ventricular outflow tract (LVOT) gradient of at least 50 mm Hg at rest or on provocation. Before the ablation procedure, diagnostic cardiac catheterization was performed in all eligible patients to confirm that a catheter could be advanced from the left radial artery into the coronary artery and to identify the presence of the septal branch, which supplies the most basal interventricular septum at the site of mitral-septal contact. Patients with a positive Allen’s test or specific contraindication for radial access were excluded. Patients provided written informed consent to proceed with ASA. 

Alcohol septal ablation procedure. Procedures were performed under local anesthesia in a catheterization laboratory by one of two interventional cardiologists with 10 or 20 years of experience with transradial PCI. A temporary pacemaker was placed in the right ventricle through a 5 Fr sheath in the jugular vein. Xylocaine was administered subcutaneously (2-4 mL of 1% solution) and both radial arteries were punctured with 18 gauge puncture needles (Supercath; Medikit); 4 Fr conventional sheaths were then introduced. After heparin 5000 U was administered, we chose the left radial artery approach for ASA and exchanged the 4 Fr sheath on this side over a J-tipped 0.035˝ wire for either a 6.5 Fr or 7.5 Fr sheathless guide catheter connected to a supplied central dilator (Figures 1A and 1B). When the sheathless guide catheter reached the proximal ascending aorta, the central dilator was removed, and the catheter was advanced to engage the left coronary ostium. 

During the procedure, a silicon-based stopper device was connected to the proximal shaft of the catheter and fixed to a surgical drape using forceps to avoid slippage (Figure 1C). If catheters needed to be exchanged during the procedure, they were exchanged over a J-tipped 0.035˝ wire. A 4 Fr pigtail catheter without side holes (Type Mtaka; Medikit) was inserted through the right radial artery and placed in the left ventricle (LV) for continuous pressure monitoring (Figure 1D). 

After coronary angiography, a 1.5-2.0 mm over-the-wire balloon was introduced into the appropriate septal perforator branch over a 0.014˝ guidewire. After the balloon was inflated to a nominal pressure, the guidewire was removed and agitated radiographic contrast was injected through the wire lumen to confirm that the balloon occluded the septal branch and excluded a retrograde spillage of contrast into the main branch of the coronary artery. Transthoracic echocardiography (TTE) was performed to identify whether the enhanced septal segment was involved with outflow tract obstruction and other myocardial tissues, such as the right ventricle wall or the papillary muscle, were not enhanced. After morphine 10 mg was administered, desiccated ethanol was infused slowly at a rate of 0.3 mL/min, with careful monitoring (electrocardiogram, pressure, fluoroscopy, and TTE). 

After 5 minutes, the balloon was deflated and removed, and coronary angiography was repeated to confirm occlusion of the target septal perforator. If there was <50% gradient reduction or an LVOT gradient of <50 mm Hg measured by TTE was not achieved, ablation of another septal perforator branch was considered. At the conclusion, the sheathless guide catheter was removed over a J-tipped 0.035˝ wire and a central dilator. Both punctured radial arteries were sealed with a compression device (Tometa Kun; Zeon Medical) that was applied according to the manufacturer’s instructions to achieve hemostasis. A temporary pacemaker was placed in the right ventricle for back-up pacing for at least 3 days. Patients left the catheterization laboratory in wheelchairs after the procedure.

Definition of primary and secondary outcomes. The primary outcome was procedural success, defined as the following composite endpoint: successful over-the-wire balloon delivery, successful desiccated ethanol infusion to targeted septal perforators, no crossover to a conventional catheter or to femoral access, and achieving a resting LVOT gradient of <50 mm Hg by TTE at discharge.

The secondary outcomes were overall survival; freedom from access-site complications, arrhythmic events, or coronary complications; resting LVOT gradient of <50 mm Hg; and NYHA functional class ≤II, with symptomatic improvement in at least one NYHA functional class. All secondary outcomes were evaluated at the 30-day follow-up. 

Access-site complications were defined as arteriovenous fistula, pseudoaneurysm, large hematoma requiring blood transfusion, spasm, and occlusion. Arteriovenous fistula and pseudoaneurysm were assessed by physical examination, before proceeding to vascular ultrasound to confirm the diagnosis. Radial artery occlusion was defined as the absence of a radial pulse by clinical assessment. Radial palpitation was performed at least the next day of the procedure and at 30-day follow-up exam and could be carried out anytime at the discretion of the doctors in charge in addition to the day after the procedure and at 30-day follow-up. Radial spasm was defined as intolerable pain experienced by the patient, or difficulty reported by the operator during insertion, manipulation, and removal of the guiding catheter. Arrhythmic events were high-grade heart block leading to permanent pacemaker implantation, ventricular tachycardia, and ventricular fibrillation. Coronary complications were coronary dissection, coronary perforation, and alcohol displacement. 

Statistical analysis. Data for continuous variables are presented as mean ± standard deviation when normally distributed and median (interquartile range [IQR]) when non-normally distributed. Data for categorical variables are presented as number (%). Comparison of continuous and ordered variables at different times was conducted using Wilcoxon signed-rank test. A P-value of <.05 was considered statistically significant. Statistical analyses were performed by using High-quality Analysis Libraries for Business and Academic Users (Gendai Sugakusha) statistical software, version 7.

Results

Baseline characteristics. Table 1 summarizes baseline clinical demographics and characteristics of the study population (n = 14 patients; 9 females (65%), mean age at initial evaluation, 70 years (IQR, 64-78 years). An automatic implantable cardioverter-defibrillator was implanted in 1 patient to prevent pulseless ventricular tachycardia. Despite previous medical treatment, 6/14 (43%) were classified as NYHA functional class III or IV, and all patients had been treated with one or more cardiac medication, including beta-blockers (93%), cibenzoline succinate (71%), verapamil hydrochloride (29%), and amiodarone (7%).The ASA procedures were performed for the first time for all the patients enrolled in the study. 

Procedural characteristics. Left radial access was obtained for ASA in all patients (Table 2); in 13 patients, 6.5 Fr sheathless guide catheters were used, and a 7.5 Fr guide catheter was used in 1 patient. The median of the total fluoroscopy time was 36.4 minutes (IQR, 26.3-50.7 minutes). The median of the delivered doses for biplane angiography during ASA procedures was 1027 mGy (IQR, 724-1382 mGy). Desiccated ethanol was injected into one septal perforator artery in 9 patients and into two vessels in 5 patients. During ablation, a median of 1.6 mL (IQR, 1.4-2.3 mL) of desiccated ethanol was injected. The median of the peak creatine kinase level was 791 IU/L (IQR, 643-1099 IU/L).

Success rate of septal ablation procedure. The primary outcome, defined by procedural success, was achieved in 13 patients (93%). One patient demonstrated an increase in her LVOT gradient to 65 mm Hg at discharge, despite successful ablation of the targeted septal perforator and achievement of an initial LVOT gradient of 22 mm Hg immediately after the procedure. It is possible that ethanol injection into another artery supplying the culprit septal segment (high lateral branch in this case) was necessary.

Delivery of both over-the-wire balloons and desiccated ethanol infusion was successful in all cases. In 2 patients, we exchanged a Judkins left sheathless guide catheter for a backup sheathless guide (Power Backup) because of the acute upward angulation of the left main trunk relative to the left sinus of Valsalva. There were no cases of crossover to a conventional 6 Fr or 7 Fr guide catheter, and no cases required conversion from radial to femoral access. The resting LVOT pressure gradient obtained by simultaneous measurements of the ascending aortic and LV pressures decreased from a median of 54 mm Hg (IQR, 34-82 mm Hg) at baseline to a median of 8 mm Hg (IQR, 0-12 mm Hg) immediately after ASA (P=.01). The resting LVOT pressure gradient obtained by TTE fell from a median of 128 mm Hg (IQR, 49-147 mm Hg) at baseline to a median of 14 mm Hg (IQR, 12-21 mm Hg) immediately after the procedure (P=.01) and a median of 22 mm Hg (IQR, 16-36 mm Hg) at discharge (P=.01) (Figure 2). 

Hemodynamic effects, symptomatic changes, and complications at 30-day follow-up exam. Clinical and echocardiographic follow-up was completed for all 14 patients after 30 days. No patient died during the follow-up duration. The resting LVOT gradient at rest was reduced from a median of 128 mm Hg (IQR, 49-147 mm Hg) at baseline to a median of 16 mm Hg (IQR, 13-26 mm Hg) at the 30-day follow-up (P=.01) (Figure 2). Significant clinical improvement was noted after ASA in all but 2 patients. The NYHA functional class improved from a median of II (IQR, II-III) at baseline to a median of I (IQR, I-I) at the 30-day follow-up exam (P=.01); no patient was classified as NYHA III or IV, and the 2 patients without symptomatic improvement were classified as NYHA II. 

There were no cases of arteriovenous fistula, spasm, pseudoaneurysm, bleeding requiring blood transfusions, radial artery occlusion, ventricular fibrillation, or ventricular tachycardia. Permanent third-degree heart block developed in 2 patients (14%), necessitating permanent pacemaker implantations (1 patient at 5 days after ASA and 1 patient at 7 days after ASA). We experienced no coronary dissection related to the sheathless guide catheters; however, the septal perforator was punctured after inflation of a 1.5 mm over-the-wire balloon and was conservatively managed in 1 patient. There were no cases of alcohol displacement. Of the 5 patients who did not achieve the secondary outcomes, 1 patient developed coronary perforation, 2 patients failed to achieve a pressure gradient <50 mm Hg and symptomatic improvement, and 2 patients developed heart block requiring permanent pacemaker implantation.

Discussion

To our knowledge, the current report is one of the first to focus on the feasibility and safety of sheathless guide catheters in transradial ASA. The main findings included high success rate, lack of a need to convert to a traditional guide, low incidence of access-site complications, and acceptable hemodynamic and symptomatic improvements.

Transradial vs transfemoral approach. Although the femoral artery is conventionally used for access in ASA,⁷ serious bleeding complications have been documented.⁸ Radial access significantly reduced such complications when compared with femoral access in PCI. On the basis of a previous report, the percentages of bleeding complications were 2.67% with radial access and 6.08% with femoral access.⁹

Previous studies on transradial ASA. To date, only one case report and one small trial have considered the feasibility and safety of the transradial approach for ASA. Groben et al reported successful ASA via the right radial artery using a conventional 6 Fr sheath.¹⁰ Cuisset et al described their experience of right radial access for ASA in 30 consecutive patients with symptomatic HOCM using a conventional 6 Fr guide catheter.¹¹ Their procedural success was 100%, and access-site bleeding complications were virtually eliminated, suggesting that ASA can be performed safely through the radial artery.

Access-site complications following transradial interventions and the advantages of sheathless guides. Potential limitations of the transradial approach include radial artery occlusion, radial spasm, and access-site bleeding. Radial artery occlusion is closely related to the use of a sheath that is larger than the arterial diameter. The mean diameter of the radial artery, as assessed by ultrasound, is reported to be significantly smaller in women than in men (2.44 ± 0.48 mm vs 2.07 ± 0.41 mm; P<.01).¹² Consequently, the diameter of the 6 Fr sheath can be larger than the radial artery diameter, particularly in women. In a recent report, radial artery patency after catheterization was assessed by high-resolution vascular ultrasound and revealed that the incidence of occlusion was higher than previously expected, ie, 13.7% using 5 Fr sheaths and 30.5% using 6 Fr sheaths.¹³ A sheathless guide may lower the incidence of occlusion, particularly for 6.5 Fr guides, because the outer diameter of a 6.5 Fr sheathless guide (2.16 mm) is smaller than the diameter of a traditional 5 Fr sheath (2.29 mm). Both the present study and the study of Cuisset et al have revealed the feasibility of transradial ASA. Although we cannot directly compare the safety of a sheathless guide to the conventional guide used in the study of Cuisset et al, from a previous report,¹³ which compared the radial artery occlusion rates of 5 Fr vs 6 Fr transradial PCI, we speculate that radial occlusion rates would be lower when using a sheathless guide catheter because the outer diameter of a sheathless guide catheter, which has an inner lumen similar to a conventional guide catheter, is approximately 2 Fr smaller than the diameter of a conventional guide.

Radial artery spasm is another very common complication of transradial intervention, reportedly occurring in up to 14.7% of PCIs.¹⁴ It causes significant discomfort and pain in patients and reduces the procedural success rate. If it occurs in patients with HOCM, it is difficult to use nitroglycerin to relieve spasm because treatment may increase the LVOT pressure gradient. Therefore, a potential solution is to perform transcatheter interventions via small radial arteries with a sheathless guide catheter that utilizes a hydrophilic coating along its entire length, including the central dilator. Notably, hydrophilic coatings have been useful in reducing the incidence of radial artery spasm.⁶ Although these catheters are feasible for transradial PCI,⁵ we are not aware of any similar detailed reports for sheathless transradial ASA. Although Cheaito et al¹⁵ briefly mention three successful cases of sheathless transradial ASA, their details have not been described.

Technical considerations for the use of sheathless guides. The sheathless guide system has a steeper learning curve for inexperienced operators. Because of its hydrophilic coating, the guide catheter can slide easily within arteries and risk disengagement from the coronary arteries, compromising guiding support. At our hospital, we often make use of a silicon-based stopper device to prevent catheters from slipping. Severe subclavian tortuosity can also make transradial interventions more difficult. Although crossover to a transfemoral approach should be considered in such cases, choosing a left radial route can minimize the risk of crossover because of less subclavian tortuosity. Furthermore, extreme care must be taken to avoid coronary ostium dissection because of the catheter’s stiffness. No catheter-related coronary dissection was noted in our study, perhaps because we paid special attention to the engagement of the guide catheters in coaxial alignment with the artery. 

Radiation exposure. In 3 out of 14 cases, the delivered radiation for biplane angiography was >2 Grays, which is the threshold range for transient erythema and temporary epilation.¹⁶ The main reason for excessive radiation exposure was requiring a long time to determine the responsible septal branch that supplies the basal third of the interventricular septum at the level of mitral-septal contact. The septal branch that we first thought to be the target was not involved with LV outflow tract obstruction. Therefore, we had to find another appropriate septal branch for ASA. Because the procedure took longer, the radiation exposure was more excessive. In the present study, for the above reason, excessive radiation exposure might not be related to the difference between radial access and femoral access.

Study limitations. Our data should be interpreted in light of the study limitations. This is a small, non-randomized, observational, single-center study with a short follow-up duration. This study did not show the superiority of the sheathless guides over conventional guides or radial over femoral procedures. This study shows only the feasibility of sheathless transradial ASA. Another potential limitation is that radial artery size was not measured. Furthermore, the definition of some complications depended on the subjective feelings of patients and subjective observations by operators (eg, radial spasm and occlusion). Further prospective multicenter studies in a larger population that compare radial access with femoral access in ASA and that compare sheathless guides with conventional guides in transradial ASA are necessary. 

Conclusions

The transradial approach using a sheathless guiding catheter is feasible and safe for ASA. Although this was a non-comparison feasibility study, our results suggest that the radial approach we described can make ASA less painful and less invasive.

References

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From the Department of Cardiology, Sendai Kousei Hospital, Sendai, Japan.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted October 1, 2014, provisional acceptance given November 24, 2014, final version accepted January 26, 2015.

Address for reprints: Dr Tsuyoshi Isawa, Department of Cardiology, Sendai Kousei Hospital, 4-15, Hirose-machi, Sendai, 980-0873, Japan. Email: isa_tsuyo@yahoo.co.jp