Anatomy and General Technique of Hemorrhoidal Embolization: History
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Hemorrhoids are blood cushions located into the anus and lower rectum, acknowledged as a common cause of bleeding, which can reduce the quality of life. The development of minimally invasive techniques such as endovascular embolization of superior rectal artery, "Emborrhoid technique", is an effective treatment, with no pain or ischemic complications, and allows quick patient recovery. 

  • hemorrhoid
  • superior rectal artery
  • bleeding

1. Introduction

Hemorrhoids (HD) are the most prevalent disease in the anorectal disorders field, representing 4% to 35% of the population; patients between 45 and 65 years old make up the highest incidence [1]. The classification of HD between internal and external comes from their location, whether above or below the dentate line (pectinate line). Internal HD often manifest with rectal bleeding, which reduces quality of life and may result in anemia [2][3].
They can be graded using the Goligher classification (GC) (Table 1), based on their degree of prolapse, and the French bleeding score (FBS) (Table 2), with a top score of 9, which implies the most intense bleeding [4].
Table 1. Goligher classification.
Table 2. French Bleeding Score.
Conservative management as dietary measures and topical medications can treat bleeding in the first instance [5][6][7][8]. However, 10% of all patients will need surgery such as conventional hemorrhoidectomy (CH) [9], circular anopexia [10], or stapled hemorrhoidopexy (SH) [11]. Over the years, less invasive techniques such as rubber band ligation (RBL) [12][13], sclerotherapy (SCL) [14][15][16], and infrared coagulation have been developed, allowing an outpatient setting and a quicker patient recovery, despite an increased recurrence. Recently, minimally invasive techniques based on the hyperflow of hemorrhoidal arteries, such as transanal hemorrhoidal dearterialization (THD) [17], doppler-guided hemorrhoidal artery ligation (DGHAL) [18][19], or its endovascular version, the “Emborrhoid technique” [20][21], have emerged, showing promising results and more patient comfort (Table 3) [22].
Table 3. Existing treatments for hemorrhoids.
Among the main advantages of hemorrhoid embolization (HE) compared with other therapies is the identification and therefore, the occlusion of all branches dependent on the superior rectal artery (SRA) and any anastomoses with the middle rectal artery (MRA) and the inferior rectal artery (IRA), which reduces recurrence of bleeding. Compared to surgery, the endovascular approach avoids rectal manipulation, eliminating the risk of rectal trauma, allowing the preservation of anal continence. Coil and particle embolization of the SRA has been found to be a well-tolerated, effective, and safe technique [23][24][25][26][27][28].
Clear indications and patient selection have not been fully specified. The Italian society of colorectal surgery [22] indicates HE to patients suffering refractory symptoms from II and III HD degrees with contraindications to surgery (level of evidence 2, grade of recommendation C).
Some studies have analyzed the impact of HE on frail patients with severe cardiovascular, pulmonary, or neurological disease, which usually contraindicates the use of general anesthesia, finding excellent modifications in hemorrhoid bleeding, anemia, and patient’s quality of life after the endovascular procedure [23]. Patients with congenital or acquired bleeding disorders have shown good responses to HE, even without suspending antiplatelet or anticoagulant therapy [24][25]. Inflammatory bowel disease stays controversial as it appears as a particular indication or contraindication in the different literature [23][25][26]. Nowadays, it is also a suitable procedure for young surgical candidates who are averse to direct rectal manipulation [27].
As contraindications, it can be found any situation that risks an endovascular procedure, like platelet count inferior to 50,000/μL, international normalized ratio (INR) superior to 1.5, allergy or intolerance to contrast media, non-available vascular access, or sepsis. Special situations that contraindicate HE are rectosigmoid resection, colorectal cancer, colonic angiodysplasia, or acute anorectal infection [23].
Considerable studies have been published on this subject, commonly using right transfemoral access (TFA). Nonetheless, many recent studies have demonstrated that transradial access (TRA) has faster ambulation and discharge but a higher radiation dose for not radial access trained specialists [26][28].

2. Anatomy

The rectum is mainly supplied by the SRA, a branch of the inferior mesenteric artery (IMA), and to a lesser extent by the MRA and IRA, branches of the internal iliac artery.
The IMA origins from the anterior and left aspect of the abdominal aorta, immediately above the iliac bifurcation, at the level of the third lumbar vertebra, and bifurcates into the left colic artery, the sigmoid arteries, and the SRA, shown in Figure 1.
Figure 1. (a) Standard vascular anatomy of IMA: left colic artery (LCA), sigmoid arteries (SA), and type I superior rectal artery (SRA) are visualized after contrast injection. (b) Type II SRA: a right main trunk crosses and gives branches to the left (arrow). (c) Prominent left middle rectal artery (MRA) and inferior rectal artery (IRA) give the main blood supply to the left wall of the distal rectum.
The anatomy of SRA was first described by Thomson in 1975, who found a common pattern in almost half of the cases, named as type I, where the main trunk divides into posterior-right and posterior-left branches and lateral-right and lateral-left branches, four branches in total. The rest of the cases were grouped into type II, where a right main trunk crosses and gives branches to the left, in type III, a left main trunk supplies the left side with a high contribution of the MRA to the corpus cavernosum recti (CCR), and type IV, the main trunk trifurcates, while in type V, the branches of the trifurcation do not reach the anal canal, because its main blood supply is done by the MRA [23][24].

3. General Technique

The “Emborrhoid technique” is generally indicated for patients with hemorrhoids type II or III and significant rectal bleeding, who have contraindications or refuse surgery, hence support by the coloproctology department must be facilitated.
Prior explanation of risk and benefit and informed consent must be obtained from each patient. Once fasting and adequate hemostasis are confirmed, the procedure is performed under aseptic conditions in a room equipped with a digital angiography. Conscious sedation is used, and local anesthetic is injected at the puncture site, which most commonly is the right femoral artery [25][26][27][28][29][30].
Simmons 2 5F (Radifocus; Terumo, Tokyo, Japan) is the most common catheter utilized to select the origin of the IMA [31][32]. In difficult catheterizations, it is also helpful to perform an inferior abdominal aortography with a Pig-tail 5F (Radifocus; Terumo, Belgium, Leuvem) (Merit; Utah, USA) and locate the c-arm in a lateral position [28].
Subsequently, there is the catheterization of the SRA with a 2.4 up to 2.7 F Progreat microcatheter® (Radifocus; Terumo, Tokyo, Japan), Direxion microcatheter HI-FLO Bern shape or J shape® (Boston Scientific; Marlborough, MA, USA) or RapidTransit microcatheter® (Cordis Endovascular Systems, Miami Lakes, FL, USA). Angiography of the SRA branches and anastomoses with MRA and inferior rectal artery (IRA) can be acquired.
Embolization of bilateral posterior and lateral branches can be performed with 2–3 mm pushable coils, such as Nester® (Cook Medical; Bloomington, IN, USA), or detachable coils, such as Target® (Stryker; Cork, Ireland) or Interlock (Boston Scientific; Marlborough, MA, USA). Some authors report bigger coil sizes of 4 to 7 mm with similar results [25][30]. Coils are the most often documented embolic material; regardless, the usage of particles and coils is preferred by some working groups. Previous injection of 300–500 μm polyvinyl alcohol (PVA) particles within the distal part of SRA branches, near the CCR; followed by coil embolization of the SRA branches themselves, may close hemorrhoid plexus more distally and obstruct persistent MRA anastomoses, as shown in Figure 2 (Table 4) [25][26][27][28][29][30][31][32]. A recent study showed that larger microspheres (900–1200 μm) have better long-term efficacy and no minor ischemic complications compared with smaller sizes [33]. Other embolization agents, like gel foam particles, have been proven effective [34].
Figure 2. Hemorrhoidal embolization. (a) Arteriography of SRA, showing the vascular anatomy of the hemorrhoidal plexus (type I); (b) Super-selective embolization of four branches of the SRA with 300–500 μm particles and 3 mm 5 cm coils, persistent MRA anastomoses in the left part of the hemorrhoidal plexus (arrow).
Table 4. Comparison between coil embolization vs. particles added to coil embolization.
It is also possible to use TRA with a 0.018-inch arterial micro-puncture set. It is advisable to puncture the left radial artery to minimize the risk of stroke. To avoid vasospasm, a “radial cocktail” (3000 IU of unfractionated heparin and 200 ugs of nitroglycerin or 2.5 mg of verapamil) is administered. Catheterization of SRA with 110 up to 150 cm-long multipurpose 4 or 5F catheter (Radifocus; Terumo, Tokyo, Japan) is advanced over a 0.035-inch × 260 cm-long glide wire, and then a 150 up to 175 cm-long microcatheter is used as TruSelect® (Boston Scientific; Marlborough, MA, USA).
Patients with TFA are discharged home one day after the intervention, and patients with TRA after 6 h. A comparison of both accesses is made in Table 5 [28][30].
Table 5. Comparison between femoral and radial access.
Patients are clinically followed up between 1 and 12 months. Technical success is considered when all the arterial network is properly embolized (Figure 2), and clinical success is when no rebleeding is observed between the first month and first year after embolization [25][26][27][28][29][30][31][32][33][34].

This entry is adapted from the peer-reviewed paper 10.3390/jcm11226631


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