Declining trend in the estimated annual rupture rate of unruptured cerebral aneurysms in Japan: a nationwide study.

The incidence of subarachnoid hemorrhages (SAHs) in Japan has recently decreased. However, trends in the annual rates of unruptured cerebral aneurysms (UCAs) are unclear because calculations based on follow-up periods are limited to patients with ruptured cerebral aneurysms. We aimed to clarify current trends in the estimated annual rupture rates of UCAs in Japan and to identify the most relevant contributing factors. We analyzed data from the Japanese Ministry of Health, Labour and Welfare and records of the Japan Neurosurgical Society. The estimated annual rupture rates of UCAs between 2003 and 2018 were calculated according to age-adjusted mortality rates of SAH and number of treated ruptured cerebral aneurysms (RCAs). We estimated trends in annual rupture rates using sensitivity analysis and assessed associations between estimated annual rupture rates and the prevalences of hypertension and current smoking. The estimated annual rupture rate of UCAs significantly decreased from 1.44 to 0.87% and from 0.92 to 0.76%, respectively, in terms of age-adjusted mortality rates of SAH and number of treated RCAs (p < 0.001). The range of changes in estimated annual rupture rates of UCAs was - 1.13%‒0.83%, representing a declining UCA trend of 88%. The estimated annual rupture rates of UCAs declined by 0.02-0.10% and 0.01-0.05% with every percent decrease in hypertension and current smoking prevalence, respectively. The estimated annual rupture rate of UCAs has recently decreased in Japan, possibly due to a decrease in the prevalence of hypertension rather than smoking.

[Thrombectomy].

Endovascular procedures have become the standard treatment for acute stroke caused by large vessel occlusion. Various strategies are available, including stent retrieval, aspiration catheter placement, and combined techniques. However, the first-pass effect can be maximized using the technique most familiar to each surgeon and institution. Therefore, it is necessary to understand the characteristics of each device and develop case-specific treatment strategies.

[Carotid Artery Stenting].

Currently, stricter indications for carotid artery stenosis are required owing to improvements in multifaceted medical treatment, including the intensive management of risk factors for atherosclerosis and lifestyle changes. High-risk factors for carotid artery stenting, such as vulnerable plaques, severe calcification, pseudo-occlusion, and difficult access, should be evaluated before endovascular intervention. Therefore, we need to understand the characteristics of each device to achieve maximum risk reduction for carotid artery stenting.

Pulsatility index of superficial temporal artery was associated with cerebral infarction after direct bypass surgery for moyamoya disease.

OBJECTIVE: Direct bypass surgery by superficial temporal artery (STA) - middle cerebral artery anastomosis is an established procedure for moyamoya disease (MMD). However, some patients may develop cerebral infarction (CI) due to the watershed shift phenomenon after the surgery. This study sought to investigate the correlation between the postoperative changes of STA flow as well as cerebral blood flow (CBF) and the incidence of CI after direct bypass surgery for MMD. METHODS: We conducted a retrospective study of 62 hemispheres in 50 subjects who underwent direct bypass surgery for MMD. All subjects underwent pre- and post-operative MR imaging, ultrasound evaluation of STA, and single-photon emission computed tomography. The presence of CI was correlated with preoperative CBF, the delta difference of each value of the STA between before and after the surgery, and the postoperative increase ratio of CBF. RESULTS: All bypass procedures were patent, and CI was observed in 4 cases (6.4%). There was no significant association between the incidence of CI and both pre- and post-operative CBF. However, there was a significant difference in delta pulsatility index (PI) of the STA between cases with or without CI (-0.38±0.22 and -0.87±0.63, respectively, p=0.03). Whereas, other factors did not show any significant differences between those with or without CI. CONCLUSIONS: A relatively high postoperative PI of the STA was significantly associated with the incidence of CI after direct bypass surgery for MMD. A larger study is needed to confirm these findings.

Usefulness of stent placement for innominate artery stenosis via the right brachial artery under protection by balloon guide catheter: a technical case report.

A method of cerebral protection during endovascular treatment for innominate artery stenosis (IAS) has not been established. Herein, we report a case of symptomatic IAS in a 76-year-old woman. A balloon guide catheter (BGC) was inserted through the right brachial artery (BA) and guided distally to the stenosis. The BGC balloon was inflated, and stenting was performed with balloon protection of both the anterior and posterior cerebral circulation, without any complications. Stenting of the IAS with the BGC using the BA approach is useful, as it is a simple technique that can prevent distal embolization.

Concentration of Lp(a) (Lipoprotein[a]) in Aneurysm Sac Is Associated With Wall Enhancement of Unruptured Intracranial Aneurysm.

BACKGROUND AND PURPOSE: Atherosclerotic remodeling of the aneurysm wall, which could be detected as aneurysm wall enhancement (AWE) by magnetic resonance-vessel wall imaging, is a part of degenerative change of unruptured intracranial aneurysms (UIAs). The purpose of this study was to determine whether the luminal concentrations of atherosclerotic proteins in the aneurysm sac were associated with increased wall enhancement of UIAs in vessel wall imaging. METHODS: We performed a prospective study of subjects undergoing endovascular treatments for UIAs. All subjects underwent evaluation using 3T-magnetic resonance imaging, including pre/postcontrast vessel wall imaging of the UIAs. Blood samples were collected from the aneurysm sac and the parent artery during endovascular procedures. Presence/absence of AWE was correlated with the delta difference in concentration for each atherosclerotic protein between the lumen of UIA and in the parent artery. RESULTS: A total of consecutive 17 patients with 19 UIAs were enrolled. The delta difference of lipoprotein(a) was significantly higher in UIAs with AWE compared with those without AWE (-6.9±16.0 versus -45.4±44.9 µg/mL, P=0.03). CONCLUSIONS: Higher luminal concentrations of lipoprotein(a) in the aneurysm sac were significantly associated with increased wall enhancement of UIAs. A larger study is needed to confirm these findings.

In-hospital mortality and poor outcome after surgical clipping and endovascular coiling for aneurysmal subarachnoid hemorrhage using nationwide databases: a systematic review and meta-analysis.

There has never been evidence for aneurysmal subarachnoid hemorrhage (aSAH) by endovascular coiling compared to surgical clipping with all grade. The present study and meta-analysis aimed to clarify the in-hospital mortality and poor outcome in the nationwide databases of patients with all grade aSAH between them. The outcome of modified Rankin scale (mRS) at discharge was investigated according to the comprehensive nationwide database in Japan. The propensity score-matched analysis was conducted among patients with aSAH in this database registered between 2010 and 2015. Meta-analysis of studies was conducted based on the nationwide databases published from 2007 to 2018. According to this propensity score-matched analysis, no significant association for poor outcome of mRS > 2 was shown between surgical clipping and endovascular coiling (47.7% vs 48.3%, p = 0.48). However, significantly lower in-hospital mortality was revealed after surgical clipping than endovascular coiling (7.1% vs 12.2%, p < 0.001). Meta-analysis of propensity score-matched analysis in the nationwide database showed no significant association for poor outcome at discharge between them (odds ratio [OR], 1.08; 95% confidence interval [CI], 0.93 to 1.26; p = 0.31). Meta-analysis of propensity score-matched analysis for in-hospital mortality was lower after surgical clipping than after endovascular coiling, however, without significant difference (OR, 0.74; 95% CI, 0.52 to 1.04; p = 0.08). Further prospective randomized controlled study with all grade aSAH should be necessary to validate the in-hospital mortality and poor outcome.

Vessel Wall Imaging of Evolving Unruptured Intracranial Aneurysms.

Background and Purpose- Unruptured intracranial aneurysms (UIAs) have various scenarios of growth and rupture. Magnetic resonance vessel wall imaging can detect aneurysmal wall thickening with inflammation and neovascularization. This study was performed to explore the vessel wall imaging findings of UIAs with consecutive follow-up. Methods- A total of 60 aneurysms with serial angiography over 2 years (mean period, 49 months, range, 24-192 months) were evaluated by vessel wall imaging. UIAs were morphologically categorized into 3 patterns: stable, whole sac expansion, or daughter sac formation. Aneurysm wall enhancement (AWE) was evaluated after administration of gadolinium. Results- Thirty-three of the 60 UIAs (55%) demonstrated no morphological changes, whereas 16 UIAS (27%) showed whole sac expansion and 11 UIAs (18%) demonstrated daughter sac formation. AWE was significantly less frequent in stable UIAs compared with UIAs showing morphological changes ( P<0.01). Aneurysms with daughter sac formation showed a significantly higher frequency of AWE than those demonstrating whole sac expansion. In the majority of UIAs with daughter sac formation, AWE was detected in the main aneurysm and not in the developing component. Conclusions- UIAs demonstrate various modes of growth. The pattern of AWE might be useful for identifying unfavorable morphological changes of UIAs.

Decreased Antiatherogenic Protein Levels are Associated with Aneurysm Structure Alterations in MR Vessel Wall Imaging.

OBJECTIVE: Thickened intracranial aneurysm wall with atherosclerotic remodeling is a part of its degenerative scenario. Current magnetic resonance (MR)-vessel wall imaging enables the detection of atherosclerotic wall thickening as aneurysm wall enhancement. The purpose of this study was to examine the correlation between identified atherosclerotic remodeling in vessel wall imaging, and systemic atherosclerosis-related risk factors. METHODS: A total of 39 aneurysms in 38 consecutive patients scheduled to undergo microsurgical clipping or endovascular coiling of intracranial aneurysms were prospectively evaluated. All patients underwent aneurysm MR-vessel wall imaging and the presence of aneurysm wall enhancement on contrast-enhanced vessel wall imaging was evaluated. The relationship between aneurysm wall enhancement and patient demographic data, aneurysm morphology and atherosclerosis-related risk factors including blood laboratory data were assessed. RESULTS: Aneurysm wall enhancement was detected in 19 of 39 intracranial aneurysms (48.7%). The maximum diameter of the intracranial aneurysm (P < .01), apolipoprotein A2 (P < .01) and apolipoprotein C2 (P = .01) was significantly associated with the presence of aneurysm wall enhancement. In multivariate logistic regression analyses, the maximum diameter of the intracranial aneurysm (odds ratio: 1.67, 95% confidence interval: 1.17-3.05) and decreased apolipoprotein A2 (odds ratio: 0.62, 95% confidence interval: 0.34-0.97) was significantly correlated with aneurysm wall enhancement. CONCLUSIONS: Rather than atherosclerotic factors, antiatherogenic proteins reduction was associated with aneurysm wall enhancement in vessel wall imaging. To elucidate antiatherogenic factors might to help find out promoting factor of unruptured intracranial aneurysms instability.

Clinicopathological Insights From Vessel Wall Imaging of Unruptured Intracranial Aneurysms.

Background and Purpose- The clinical significance of vessel wall imaging (VWI) remains unclear in patients with unruptured intracranial aneurysms. This study was performed to investigate the correlations between aneurysm wall imaging findings and histopathologic aneurysm wall architectures. Methods- A total of 9 aneurysms was evaluated by VWI and subsequently characterized with histopathology. We used VWI to visualize the aneurysm wall and determine if there was aneurysm wall enhancement after gadolinium contrast administration. Results- Aneurysm wall structures were identified in 6 of 9 unruptured intracranial aneurysms by native VWI, and wall enhancement was identified in 5 of these 6 aneurysms. Histopathologic studies revealed that wall thickening accompanied by atherosclerosis, neovascularization, and macrophage infiltration corresponded to visualization of the aneurysm wall by native VWI and to aneurysm wall enhancement. Conclusions- VWI can visualize thickening of the aneurysm wall, and wall enhancement corresponded to histologically confirmed degenerative changes accompanied by neovascularization and prominent macrophage infiltration.

One year Rat Study of iBTA-induced "Microbiotube" Microvascular Grafts With an Ultra-Small Diameter of 0.6 mm.

OBJECTIVE: The world's smallest calibre "microbiotube" vascular graft was recently developed, with an inner diameter of 0.6 mm. It was formed using in-body tissue architecture (iBTA) and has a high degree of patency and capacity for regeneration in the acute phase, 1 month after implantation. This consecutive study investigated the compatibility and stability of microbiotubes in the chronic phase of implantation for 12 months for potential application in microsurgery. METHODS: This was an in vivo experimental study. The microbiotubes were prepared by embedding the mould subcutaneously in rats for 2 months. Allogenic microbiotubes (n = 16) were implanted into the bilateral femoral arteries (inner diameter 0.5 mm) of eight Wistar rats in an end to end anastomosis manner for 12 months. Follow up 7-Tesla magnetic resonance angiograms were performed every 3 months. Histological observation was performed 12 months after implantation. RESULTS: All patent grafts (n = 12, patency 75%) one month after implantation maintained their patency up to 12 months without any abnormal morphological changes or calcification. Histological observation at 12 months showed that layered α-smooth muscle actin positive cells with a monolayer luminal covering of endothelial cells had formed from the proximal to the distal anastomoses. A thin elastic fibre layer formed in the luminal area. After implantation, all components of the microbiotube were similar to those of a native artery. CONCLUSIONS: This study suggests that microbiotubes have high compatibility, stability, and durability as replacement grafts over the short to mid-term period.

Analysis of outcome at discharge after aneurysmal subarachnoid hemorrhage in Japan according to the Japanese stroke databank.

The outcomes at discharge for ruptured cerebral aneurysms after subarachnoid hemorrhage (SAH) were investigated using data from the Japanese stroke databank. Among 101,165 patients with acute stroke registered between 2000 and 2013, 4693 patients had SAH caused by ruptured saccular aneurysm. Of these, 3593 patients (1140 men and 2453 women; mean age 61.3 ± 13.7 years) were treated by surgical clipping (SC) and/or endovascular coiling (EC). The outcomes of modified Rankin scale (mRS) at discharge were compared between the SC and EC groups. There were 2666 cases in the SC group, 881 cases in the EC group, and 46 cases in the SC and EC group. The rates of poor outcome of mRS > 2 were 33.0 and 45.5% in the SC and EC groups (p < 0.05), respectively. Cases were selected using two types of criteria compatible with both treatments. Under the first compatible criteria, the rates of poor outcome of mRS > 2 were 18.9 and 24.8% in the SC and EC groups (p < 0.05), respectively. Under the second compatible criteria, the rates of poor outcome of mRS > 2 were 16.0 and 14.8% in the SC and EC groups (p = 0.22), respectively. No significant differences were found in clinical characteristics or outcomes between the two groups. Multivariate analysis of aneurysmal SAH revealed no significant risk for poor outcome associated with the treatment method. The present study was not a randomized controlled study, but no significant differences in mRS at discharge were found between SC and EC in the Japanese stroke databank.

Effect of actual age on outcome at discharge in patients by surgical clipping and endovascular coiling for ruptured cerebral aneurysm in Japan.

The Japanese population features the highest rate of elderly individuals worldwide. However, the difference of actual age indication for surgical clipping (SC) and endovascular coiling (EC) has never reported. We clarified the effect of actual age on poor outcome at discharge in patients by each treatment for ruptured cerebral aneurysm according to the Japanese Stroke Data Bank. A total of 3593 patients with ruptured saccular cerebral aneurysm were treated by SC and/or EC between 2000 and 2013. The effect of actual age on poor outcome (modified Rankin scale [mRS] score > 2) at discharge was evaluated by the cutoff age using receiver operating characteristic analysis for each treatment. There were 2666 cases in the SC group and 881 cases in the EC group. The cutoff age for poor outcome was 3 to 9 years older for EC than for SC. The gap of cutoff age between two treatments was 3 years shorter in mild subarachnoid hemorrhage than severe cases. The gap of cutoff age between two treatments was 7 years in elderly patients over 65 years old. The cutoff age was 78 years old for both SC and EC in elderly female patients. In conclusion, the cutoff age for poor mRS score > 2 was 3 to 9 years older for EC than for SC. Actual age was one of the indications for elderly patients to achieve the optimum outcome; however, the treatment indication should be carefully considered based on the condition in each country.

Overlapped Stenting Is Associated with Postoperative Hypotension after Carotid Artery Stenting.

BACKGROUND: Hypotension (HT) is well recognized to frequently occur during and after carotid artery stenting (CAS), which sometimes causes postoperative complications such as stroke or myocardial infarction. This study aimed to examine the risk factors associated with HT after CAS based on the hypothesis that overlapped stenting may affect postoperative HT. METHODS: A total of 106 lesions in 95 patients with carotid artery stenosis who underwent CAS were reviewed. Bradycardia and HT were defined as a heart rate and a systolic blood pressure less than 60 beats/min and 100 mm Hg, respectively. The patients were categorized by the presence (group H) or the absence (group N) of postoperative HT, respectively, and demographic data, risk factors, conditions of carotid artery stenosis, procedures, and pre- and intraoperative hemodynamics were compared between these 2 groups. Multivariate analysis was performed to evaluate independent factors associated with postoperative HT. RESULTS: In total, postoperative HT was observed in 30 (28.3%) cases. The incidence of overlapped stenting, the use of an open-cell stent, and intraoperative HT were significantly higher in group H (P = .03, .01 and < .01, respectively). The distance from carotid bifurcation and the maximum stenotic lesion tended to be shorter in group H (P = .09). In the multivariate logistic regression analysis, using all these variables, the overlapped stenting and intraoperative HT were found to be independent predictors for postoperative HT. CONCLUSION: The overlapped stenting affected postoperative HT after CAS. Blood pressure should be strictly controlled in cases with overlapped stenting or intraoperative HT after CAS.

Development of in vivo tissue-engineered microvascular grafts with an ultra small diameter of 0.6 mm (MicroBiotubes): acute phase evaluation by optical coherence tomography and magnetic resonance angiography.

Biotubes, i.e., in vivo tissue-engineered connective tubular tissues, are known to be effective as vascular replacement grafts with a diameter greater than several millimeters. However, the performance of biotubes with smaller diameters is less clear. In this study, MicroBiotubes with diameters <1 mm were prepared, and their patency was evaluated noninvasively by optical coherence tomography (OCT) and magnetic resonance angiography (MRA). MicroBiotube molds, containing seven stainless wires (diameter 0.5 mm) covered with silicone tubes (outer diameter 0.6 mm) per mold, were embedded into the dorsal subcutaneous pouches of rats. After 2 months, the molds were harvested with the surrounding capsular tissues to obtain seven MicroBiotubes (internal diameter 0.59 ± 0.015 mm, burst pressure 4190 ± 1117 mmHg). Ten-mm-long MicroBiotubes were allogenically implanted into the femoral arteries of rats by end-to-end anastomosis. Cross-sectional OCT imaging demonstrated the patency of the MicroBiotubes immediately after implantation. In a 1-month follow-up MRA, high patency (83.3 %, n = 6) was observed without stenosis, aneurysmal dilation, or elongation. Native-like vascular structure was reconstructed with completely endothelialized luminal surfaces, mesh-like elastin fiber networks, regular circumferential orientation of collagen fibers, and α-SMA-positive cells. Although the long-term patency of MicroBiotubes still needs to be confirmed, they may be useful as an alternative ultra-small-caliber vascular substitute.

Efficacy of cilostazol in prevention of bradycardia during carotid artery stenting.

BACKGROUND: Hypotension and bradycardia are known to occur frequently in carotid artery stenting (CAS), which may lead to postprocedural complications. The purpose of this retrospective study was to assess the efficacy of cilostazol, a phosphodiesterase 3 inhibitor, for preventing bradycardia and hypotension in the periprocedural period. METHODS: The study population comprised 53 patients (54 lesions) with carotid artery stenosis who underwent CAS at our institution between 2004 and 2008. The patients were categorized by the use (group C, n = 26) or nonuse of cilostazol (group N, n = 28). The incidences of intraprocedural and postprocedural hypotension and bradycardia in each group were statistically assessed. RESULTS: Intraprocedural hypotension and bradycardia occurred in 9 cases (34.6%) and 4 cases (15.3%) in group C and in 5 cases (17.9%) and 15 cases (53.6%) in group N, respectively. Postprocedural hypotension and bradycardia occurred in 4 cases (15.4%) and 0 cases in group C and in 1 case (3.6%) and 3 cases (10.7%) in group N, respectively. The incidence of intraprocedural bradycardia (IBc) was significantly lower in group C (P = .0035). Logistic regression analysis revealed that the use of cilostazol decreased the risk of IBc 99.5% (odds ratio [OR] = .01, 95% confidence interval [CI]: 5.46 × 10(-6) to .04, P = .001) and distance from carotid bifurcation to maximum stenotic lesion was independently associated with IBc (OR = .46, 95% CI: .29-.74, P = .001). CONCLUSION: Use of cilostazol was associated with a lower incidence of IBc. Cilostazol may be a useful drug for the prevention of this complication.

Endovascular Treatment for Ruptured Intracranial Aneurysms with Intracerebral Hematoma-Clinical Propriety of Less Invasive Treatment.

BACKGROUND: Endovascular treatment of ruptured intracranial aneurysms (rIAs) accompanied by intracerebral hematoma (ICH) can be challenging because the ICH can be enlarged due to intraoperative anticoagulation during the endovascular procedure. This retrospective study aimed to compare the outcomes of aneurysmal subarachnoid hemorrhage with and without ICH treated by endovascular procedures. METHODS: We reviewed 62 patients who underwent endovascular treatment of rIAs between January 2015 and April 2023. The patients were divided into 2 groups: those with ICH (group H; n = 13) and those without ICH (group N; n = 49). The patient demographics, aneurysm characteristics, World Federation of Neurosurgical Societies (WFNS) grade, complications (e.g., symptomatic vasospasm, hydrocephalus), and outcomes were assessed stratified by the presence of ICH. In group H, age, sex, complications, WFNS grade, and hematoma volume were also analyzed in relation to the outcomes at discharge. RESULTS: None of these patients required removal of ICH after endovascular treatment of the rIA. We found no significant differences in patient characteristics, aneurysm morphologies, WFNS grade, or overall outcomes between the 2 groups. In contrast, only a poor WFNS grade was significantly associated with poor outcomes (modified Rankin scale score ≥3) in group H (P = 0.04), and the ICH volume was not significantly different between those with good (6.2 ± 5.8 mL) and poor (14.6 ± 10.4 mL) outcomes in group H (P = 0.20). CONCLUSIONS: Endovascular treatment without hematoma evacuation did not adversely affect the outcomes of rIAs with ICH when the clinical condition and aneurysm morphology permitted. Surgical invasion might be avoidable with this less-invasive strategy without worsening the outcomes.

Outcome of CAS under flow reversal and analysis for the intraprocedural flow of internal carotid artery.

OBJECTIVE: Carotid artery stenting (CAS) under flow reversal with dual protection using a proximal balloon and distal filter has been an established procedure for internal carotid artery (ICA) stenosis. This study investigates the effect of external carotid artery (ECA) occlusion on outcomes of CAS and ICA flow under flow reversal. METHODS: We reviewed 231 cases of CAS under flow reversal with ECA occlusion and 32 without. In the last 14 of 32 cases, the flow in the ICA under flow reversal was analyzed by ultrasound. The collateral index, which was defined as the total value of the maximum diameters of the ipsilateral anterior cerebral artery at the A1 segment and the anterior communicating artery, as well as those of the ipsilateral posterior cerebral artery at the P1 segment and the ipsilateral posterior communicating artery, and the maximum diameter of the ipsilateral ECA were correlated with the flow direction in the ICA. RESULTS: There was no significant difference in the outcome of CAS between the groups with or without ECA occlusion. Among the 14 cases without ECA occlusion, antegrade flow in the ICA was observed in 6 cases (42.9 %). The group with the antegrade flow in the ICA exhibited a significantly lower collateral index (5.08±0.33 vs 6.71±0.28, p=0.01) and a significantly larger ECA diameter (4.66±0.51 mm vs 3.21±1.24 mm, p=0.01) than the group with the stagnant or retrograde flow in the ICA. CONCLUSIONS: The outcomes of CAS under flow reversal were acceptable even without ECA occlusion. The ECA occlusion may not be necessary for CAS under dual protection; however, distal filter protection should be used even under flow reversal.

Usefulness of combined bypass surgery for moyamoya disease in infants under 1 year of age: A technical case report.

Background: Among pediatric cases of moyamoya disease (MMD), cerebral ischemic symptoms often progress and worsen rapidly in infants under one year of age; therefore, it is important to treat them as early as possible. However, direct bypass surgery is often technically difficult for infants due to their small blood vessels. Here, we describe our technique to resolve the technical challenges encountered during superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass surgery in infants aged <1 year with MMD, focusing on specific procedures. Case Description: We performed bilateral STA-MCA and indirect bypass in a 1-year-old girl with MMD and cerebral infarction. Before treatment, a peripherally inserted central venous catheter (PICC) was placed to avoid ischemic attacks associated with crying, dehydration, and malnutrition. All examinations and procedures that would be stressful to the patient, such as blood examinations, were performed using PICC or under sedation. The STA-MCA diameters were 0.8 and 1.2 mm, respectively. After suturing the planned anastomosis with one stitch using an 11-0 monofilament nylon thread, the thread was lifted upward, and the arterial wall was incised. Anastomosis was performed using an 11-0 monofilament nylon thread with 2-4 stitches on each side. The operation was completed without patency problems. Postoperative blood flow improved, and the patient had a good treatment course. Conclusion: Direct bypass for MMD patients aged <1 year is technically challenging; however, the vessels can be connected if the procedure is carefully performed with consideration of the characteristics of the infant's vessels.