Complications of hyaluronic acid fillers and their managements

A hypoxic young lady in an acute confusional state

Patients presenting with respiratory and neurological symptoms after a breast filler injection should alert the clinician to this potential diagnosis https://bit.ly/3OodFQA.

A rare case of gingival necrosis following an extraoral injection of dermal filler

BACKGROUND

The utilization of dermal fillers for cosmetic procedures has increased dramatically in the past several years, and so is the number of reported adverse events and complications. Most of these reports are centered on extraoral facial structures such as skin, nose, forehead, and eyes. However, as this report illustrates, intraoral complications are also possible and require appropriate management. Our extensive search of the medical and dental literature has failed to yield any such report.

METHODS AND RESULTS

An injection of dermal filler composed of hyaluronic acid for managing a deep nasolabial fold resulting in an arterial occlusion is presented. Patient exhibited facial skin necrosis, with ecchymoses and crusting, extending to the right eye. Transient diplopia and vision changes were also present. Additionally, intraoral necrosis of the palatal mucosa extending from the right central incisor to the molars and approaching the midline was noted. Patient was managed palliatively until complete re-epithelization was noted, with no further loss of periodontal attachment.

CONCLUSION

This case illustrates a rare oral complication of extraoral injection of a dermal filler, and its management. The clinicians should be aware of the potential risks of these cosmetic procedures. Early detection and timely management may prevent lasting damage and discomfort. Additionally, some of these complications may require a well-coordinated multidisciplinary involvement to restore health and functions (plastic surgeon, dermatologist, ophthalmologist, and a periodontist).

KEY POINTS

Why is this case new information? Previous reports of adverse effects linked to dermal fillers were limited to extraoral structures such as the facial skin, nose, forehead, and eye. To the authors' best knowledge, this is the first and only documented case of intraoral necrosis following dermal filler injection What are the keys to successful management of this case? The most important step in managing intra-arterial filler injection and occlusion is the immediate injection of hyaluronidase enzyme to minimize the extent of tissue necrosis. In the case of ocular involvement, immediate referral to an ophthalmologist is required What are the primary limitations to success in this case? Success of managing the adverse effects of vascular occlusion following filler injection depends on several factors, including the anatomical area of occlusion, its extend, along with timely treatment.

A Comparison Between Hyaluronic Acid Filler and Dermofat Grafts With or Without Tie-Over Dressing for Lip Augmentation

BACKGROUND

There are many different autologous grafts used for lip augmentation, such as fat, fascia, or dermofat grafts (DFG). However, filling with synthetic materials such as hyaluronic acid (HA) fillers is the most preferred method.

OBJECTIVE

The authors aimed to compare DFG with HA fillers regarding cost, permanence, complication rate, gained volume, and satisfaction rate. The authors investigated the effect of tie-over dressings on the viability of DFG.

PATIENTS AND METHODS

Patients who received hyaluronic acid fillers were referred to as Group H. Patients who received grafts without tie-over and with tie-over dressings formed Groups D1 and D2, respectively. The lip index (LI) was used for volume comparisons. The viable area of the grafts was measured using ultrasound imaging.

RESULTS

At postoperative month 6, the only significant difference was found between Group D1 and Group D2 ( p < .05). At the postoperative first year, Groups D1 and D2 had a statistically higher LI value compared with Group H. Group D2 had a higher viable area than Group D2 ( p < .05). Group H and Group D2 showed higher satisfaction scores than Group D1 ( p < .05).

CONCLUSION

Dermofat grafts with or without tie-over dressings can be considered a reliable and inexpensive choice for patients who seek a more permanent procedure. Tie-over dressings increase the predictability of DFG and reduce the need for overcorrection.

Effectiveness and Role of Using Hyaluronic Acid Injections for Gluteal Augmentation: A Comprehensive Systematic Review of Techniques and Outcomes

INTRODUCTION

There has been a rapid increase in the number of patients undergoing non-surgical gluteal augmentation in recent years, leading to an increase in the number of articles in the literature regarding the use of hyaluronic acid (HA) for gluteal augmentation. No systematic review has been published on the effectiveness of HA for gluteal augmentation. This study aimed to provide a comprehensive review regarding the effectiveness and role of using HA for gluteal augmentation.

METHODS

This review was conducted according to the PRISMA guidelines for reporting systematic reviews and meta-analyses. We conducted a search across MEDLINE, EMBASE, Cochrane, and Google Scholar, using the following search keywords: gluteus, buttocks, gluteoplasty, gluteal augmentation, hyaluronic acid, and filler.

RESULTS

Ten articles published between 2013 and 2022 that included 168 patients. The estimated duration of product effectiveness is 16.16 months. Most studies showed statistically significant improvements in patients' satisfaction. Mean volume of HA injected for optimal gluteal fat augmentation was 206.71 ml. Of included studies, two reported major complications, five patients experienced bruising and erythema as minor complications, five patients experienced effusion and inflammation at the injection site, three patients experienced gel dislocation, and one patient experienced irregular contours.

CONCLUSIONS

Based on our findings, HA is a predictable method for gluteal augmentation. Patients were satisfied with their outcomes. Despite gluteal augmentation with HA having a modest complication rate, it can still involve serious complications such as diffuse alveolar hemorrhage and death. There is a need for further research in a randomized control trial.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these evidence-based medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Antibacterial self-healing bilayer dressing for epidermal sensors and accelerate wound repair

This study aimed to investigate the effect of the bilayer hydrogel as a wound dressing on the wound-healing rate. We synthesized a self-healing hydrogel with optimized formulation by introducing natural polymer (chitosan) and arginine to the hydrogel composition. We then characterized the hydrogels using FT-IR, thermal analysis, mechanical testing, and in vitro and in vivo assay. The resulting bilayer wound dressing offers a lot of desirable characteristics, including good self-healing and repeatable adhesiveness. Likewise, the conductive bilayer wound dressing could be used to analyze the patient's healthcare data in real-time as epidermal sensors. Bilayer wound dressings remarkably have broad antibacterial efficacy against Gram-positive and Gram-negative bacteria. The potential applications of this bilayer wound dressing are illustrated by detectable body movement and conductivity. The wound-healing rate of bilayer wound dressings containing chitosan and arginine was higher, but those without the aforementioned ingredients had lower wound-healing efficacy. Additionally, promoting collagen synthesis and reducing wound infection has a considerable therapeutic impact on wounds. These results could have significant implications for the development of high-performance wound dressings.

A case of acute motor sensory axonal neuropathy variant of Guillain Barre syndrome and anaphylaxis reaction as a complication from hyaluronic acid breast enhancement from an unlicensed beautician

Guillain Barre syndrome (GBS) as a complication of hyaluronic acid (HA) exposure is an extremely rare occurrence. We report a case of GBS, acute motor sensory axonal neuropathy (AMSAN) variant, after a HA breast enhancement procedure. A 41-year-old lady underwent a HA breast enhancement procedure from an unlicensed beautician and developed anaphylaxis followed by bilateral breast abscess and neurological deficits involving both motor and sensory components. The AMSAN variant of GBS was diagnosed from the cytoalbuminologic dissociation and nerve conduction study. Her GBS and breast abscess were managed with plasmapheresis and bilateral mastectomy. In this case, GBS was highly suspected to be caused by HA with possible impurities. To the author's knowledge, the association between HA and GBS has not been reported or known, and further studies are required to establish this association. To prevent mortality and morbidity, breast enhancement procedures should be performed by trained professionals with properly vetted products.

Adverse Events Reported From Hyaluronic Acid Dermal Filler Injections to the Facial Region: A Systematic Review and Meta-Analysis

Dermal filler injections are one of the most popular cosmetic procedures in the United States. Of the many options available, hyaluronic acid (HA) dermal fillers like Juvederm or Restylane are often used. Despite their use and popularity, adverse events are known to occur from these procedures. Although most outcomes may be mild and resolve over time, rare instances of severe complications cannot be ignored, as these effects may be irreversible. Healthcare practitioners and patients must be aware of these risks, as these cosmetic procedures can affect the patient's quality of life. The aim of this study was to evaluate the incidence of adverse events (AEs) reported from the use of hyaluronic acid dermal fillers in the facial region. A systemized search of randomized controlled trials was conducted using Cochrane Central, Embase, Medical Literature Analysis and Retrieval System Online (MEDLINE), and the Web of Science databases. After screening for eligibility and conducting a critical appraisal of the articles, 19 studies were retained for the final review. The meta-analysis results included different side effects by facial location, i.e., nasolabial fold (NLF) vs. other (midface, perioral line, and lip region). The midface includes the anteromedial cheek region, the zygomaticomalar region, and the submalar region. The adverse events were swelling, pain, erythema, bruising, lumps and bumps, firmness, tenderness, itching, and skin discoloration. A significant difference was found in the proportion of individuals experiencing swelling, lumps or bumps, and firmness at the nasolabial fold site versus the midface, perioral line, and lip region. There was no significant difference in the proportion of individuals experiencing pain, erythema, bruising, tenderness, itching, or skin discoloration at the nasolabial fold site versus the other sites. The study highlights the prevalence of common AEs that can result from HA dermal fillers like Juvederm or Restylane, thus emphasizing the importance of healthcare professionals explaining the risk and benefits to patients.

Acute unilateral vision loss and bilateral cerebral infarction following cosmetic filler injection

The current case report describes acute unilateral vision loss and bilateral cerebral infarction as devastating complications following cosmetic injection of hyaluronic acid to the nasal bridge in a 34-year-old female. The patient reported the onset of sudden eye pain, headache, and vision loss in her right eye. At the initial visit to the hospital, the patient had no light perception in the right eye. Examinations revealed marked ptosis and complete ophthalmoplegia with no proptosis. At the time of the patient's hospital evaluation, computed tomography, and magnetic resonance imaging were ordered. Few mottled materials (denser than blood) were observed in the cavernous sinus with a density of 106 Hounsfield units (HU), yet no air was depicted in the cavernous sinus. MRI scan revealed multiple areas of bilateral intracranial infarcts. Although cosmetic injection of hyaluronic acid has been documented as a safe procedure, vision loss remains one of the most feared complications.

Bridging a Century-Old Problem: The Pathophysiology and Molecular Mechanisms of HA Filler-Induced Vascular Occlusion (FIVO)—Implications for Therapeutic Interventions

Biocompatible hyaluronic acid (HA, hyaluronan) gel implants have altered the therapeutic landscape of surgery and medicine, fostering an array of innovative products that include viscosurgical aids, synovial supplements, and drug-eluting nanomaterials. However, it is perhaps the explosive growth in the cosmetic applications of injectable dermal fillers that has captured the brightest spotlight, emerging as the dominant modality in plastic surgery and aesthetic medicine. The popularity surge with which injectable HA fillers have risen to in vogue status has also brought a concomitant increase in the incidence of once-rare iatrogenic vaso-occlusive injuries ranging from disfiguring facial skin necrosis to disabling neuro-ophthalmological sequelae. As our understanding of the pathophysiology of these injuries has evolved, supplemented by more than a century of astute observations, the formulation of novel therapeutic and preventative strategies has permitted the amelioration of this burdensome complication. In this special issue article, we review the relevant mechanisms underlying HA filler-induced vascular occlusion (FIVO), with particular emphasis on the rheo-mechanical aspects of vascular blockade; the thromboembolic potential of HA mixtures; and the tissue-specific ischemic susceptibility of microvascular networks, which leads to underperfusion, hypoxia, and ultimate injury. In addition, recent therapeutic advances and novel considerations on the prevention and management of muco-cutaneous and neuro-ophthalmological complications are examined.

Inflammatory Reactions to Laryngeal Injection of Hyaluronic Acid Derivatives

OBJECTIVES/HYPOTHESIS

To report the rate and describe the characteristics and management of inflammatory reactions following injection laryngoplasty with hyaluronic acid derivatives.

STUDY DESIGN

Single institution, retrospective review.

METHODS

Adult and pediatric patients who underwent injection laryngoplasty with hyaluronic acid derivatives from 2013 to 2020 were identified. Demographics, indication for injection, type and volume of injected material, and use of general anesthesia were obtained. When a postoperative inflammatory response occurred, information regarding clinical presentation, timing, and subsequent management was collected.

RESULTS

A total of 464 patients who underwent 536 laryngeal injections with hyaluronic acid derivatives were included. There were 365 adult patients (median age 62 years) who underwent 431 injections and 99 pediatric patients (median age 2 years) who underwent 105 injections. The most common indications for injection were abnormal vocal fold mobility (70.3%) and aspiration (83.8%) for adult and pediatric patients, respectively. Juvéderm® was used in 449 cases (79.8% adult, 100% pediatric), and Restylane® was used in the remaining adult cases (20.2%). Procedures were mostly performed under general anesthesia (67.7% adult, 100% pediatric) with median injection volumes of 0.6 mL for adult and 0.3 mL for pediatric patients. An inflammatory reaction occurred following 3 of 536 injections (0.6%), all utilizing Juvéderm®. All three patients presented with stridor, dyspnea, and laryngeal edema within two days of injection. Each patient was admitted for observation and successfully treated with intravenous steroids and inhaled racemic epinephrine. One patient with comorbid pneumonia was intubated and required concomitant treatment with broad-spectrum antibiotics.

CONCLUSIONS

Inflammatory reactions to hyaluronic acid derivatives used in injection laryngoplasty are rare but represent significant patient morbidity and can be managed with anti-inflammatory and airway stabilizing measures. Patients should be counseled appropriately regarding the risks of injection laryngoplasty with hyaluronic acid derivatives.

A systematic review on COVID-19 vaccination and cosmetic filler reactions: A focus on case studies and original articles

Background

Tissue fillers are among the most popular cosmetic procedures performed and notably, cases of filler reactions after COVID‐19 vaccination have been reported.

Objective

The objective was to determine the characteristics of patients with filler reaction after COVID‐19 vaccination and address several considerations that have to be taken into practice.

Methods

A PRISMA compliant systematic search was conducted in Scopus, Web of Science, and PubMed/MEDLINE databases for articles published from inception up to October 21, 2021.

Results

Out of 106 initially retrieved articles, four of them were included in our study, and a total number of 13 cases were analyzed. In this study, we found that all of the patients who developed delayed‐type reaction (DTR) following COVID‐19 vaccination were middle‐aged women without any known history of allergy to foods or drugs. All patients had a history of hyaluronic acid (HA) filler injection in their head and neck and demonstrated symptoms particularly swelling, from <1 day up to 10 days after the first or second doses of vaccines. Lisinopril, hyaluronidase, and corticosteroids seemed to have good results in management.

Conclusion

Although rare, DTR to fillers after COVID‐19 vaccination can happen. Physicians should be aware of the pathogenesis and management of this phenomenon.

Injection Guidelines for Treating Midface Volume Deficiency With Hyaluronic Acid Fillers: The ATP Approach (Anatomy, Techniques, Products)

Midface rejuvenation is among the most valuable indications of hyaluronic acid dermal fillers, because malar projection and full upper cheeks significantly contribute to a youthful appearance. Hyaluronic acid fillers have evolved over the past 2 decades to meet specific clinical needs such as strong projection capacity and adaptability to facial dynamism. As a result, they now represent the treatment of choice for midface rejuvenation throughout age ranges by offering the potential for noninvasive treatment, immediate results, and minimal downtime. Because the 5-layered structure of the midface plays a central role in the human face, injecting the midface area may also indirectly improve other aesthetic concerns such as infraorbital hollowing and nasolabial folds. Nonetheless, midface rejuvenation requires a tailored treatment approach and a thorough knowledge of anatomy to minimize procedural risks and achieve natural-looking results. This article provides an extensive anatomical description of the midface and of the usual course and depth of vascular structures circulating nearby to delineate a treatment area and minimize procedural risks. Furthermore, considering the differential mobility and mechanical constraints of each layer of the midface, a multilayer treatment algorithm is proposed for adapting the treatment strategy to patient specificities (including age, gender, skin type, and morphology). Emphasis is also placed on desirable filler properties to create deep structural support on the one hand and accompany facial movement on the other hand.

Periorbital rejuvenation: A study on the use of dermal threads as monotherapy, with a review of literature

The periorbital region, a major impressionable area holds a special place in aging of the face. It reflects chronological aging which are reflected not only as structural changes but also emotive expressions of sadness and tiredness. Dermal threads have been used in combination with other aesthetic procedures, however their use as monotherapy especially in periorbital region needs evaluation.

Crosslinking Hyaluronic Acid Soft-Tissue Fillers: Current Status and Perspectives from an Industrial Point of View

INTRODUCTION

Hyaluronan (HA)-based soft-tissue fillers are injectable crosslinked hydrogels aimed to counteract facial skin aging signs via minimally invasive procedures. The crosslinking step is required to drastically improve HA residence time in vivo and provide the gel with specific viscoelastic properties matching the clinical indications. While HA as a raw material and HA fillers are widely studied, little is reported about crosslinkers themselves used in commercial fillers.

AREAS COVERED

This article introduces the specifications of the ideal crosslinker in HA fillers. The properties of commercially used crosslinkers are reviewed. An up-to-date review of innovative hydrogel fabrication alternatives is conducted, and advantages and drawbacks are discussed.

EXPERT OPINION

HA fillers are predominantly manufactured using 1,4-butanediol diglycidyl ether (BDDE) which is considered as the gold standard crosslinker worldwide due to its proven and unrivalled clinical track record of more than 20 years. Extensive studies have been published covering BDDE-crosslinked HA fillers' chemistry, gel properties, and clinical effectiveness and safety. However, new hydrogel fabrication strategies have emerged, paving the way for innovative alternatives potentially bringing novel features to HA fillers. Nevertheless, major efforts must still be implemented to assess their safety, efficacy, stability and suitability for industrialization.

Hyaluronic Acid Embolism Treated with Subcutaneous High and Low Hyaluronidase Doses: Efficacy and Surrounding Tissue Effect

BACKGROUND

The use of hyaluronidase in hyaluronic acid vascular occlusion has been evaluated; however, the models used do not accurately assimilate the facial morphologic characteristics or study the effects on adjacent tissues. The purpose of this study was to determine an effective concentration of subcutaneous hyaluronidase to dissolve a hyaluronic acid embolism and its effect on surrounding tissue.

METHODS

Fifteen rabbits were divided into six groups. An inguinal incision was performed on the femoral artery to create a hyaluronic acid embolism in the control and treatment groups (low-, medium-, and high-hyaluronidase groups). Hyaluronidase was injected subcutaneously. Photographic follow-up, histologic analysis, and quantification of hyaluronic acid were performed. Kruskal-Wallis test and post hoc with Bonferroni correction (p < 0.05) was used to compare the presence of hyaluronic acid in the arterial lumen between groups.

RESULTS

Despite the persistence of intravascular hyaluronic acid, macroscopic and microscopic differences were found between the embolism control group and embolism hyaluronidase high-dose group. Histologic analysis demonstrated thrombosis throughout groups. Skeletal muscle was least affected in the embolism hyaluronidase 500 IU group with less lysis and inflammatory infiltrate.

CONCLUSIONS

A 500 IU hyaluronidase dose partially prevents the damage caused by the embolism, and does not affect the surrounding tissue. The use of thrombolytic therapy combined with higher doses of hyaluronidase subcutaneously in this model is proposed.

Ultrasonographic Subclinical Signs of Inflammation of the Lacrimal, Parotid, and Submandibular Glands in Users of Cosmetic Fillers

OBJECTIVES

To detect ultrasonographic inflammatory signs in the lacrimal, parotid, and submandibular glands in cosmetic fillers (CFs) users.

METHODS

A prospective and cross-sectional ultrasound study of the glands in cases with CFs was performed. The sample included users of hyaluronic acid, silicone oil, polymethylmethacrylate, polycaprolactone, calcium hydroxyapatite, and polyacrylamide. Abnormalities of the parenchyma and hypervascularity signs of the glands were compared with a control group (n = 10), evaluated by 2 observers, and correlated with the type, number, and location of the facial CFs. Cohen's kappa test and logistic regression models with odds ratios (OR) adjusted by age with 95% CI were performed.

RESULTS

Sixty-three patients with CFs met the criteria. Parotid and submandibular glands had the highest percentage of parenchymal involvement: 87.3 and 88.9%, respectively (p <.01). Abnormalities of the echostructure of the parenchyma and hypervascularity of the glands were detected with all kinds of fillers without significant differences per type. A significant substantial interrater kappa (0.61) with an agreement of 90% for all glands among observers was found.

CONCLUSION

Users of common types of CFs frequently present subclinical ultrasonographic signs of inflammation of the lacrimal, parotid, and submandibular glands. Further research on the topic seems necessary.

Tissue Fillers for the Nasolabial Fold Area: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Abstract

Tissue fillers injections remain to be one of the most commonly performed cosmetic procedures. The aim of this meta-analysis was to systematize and present available data on the aesthetic outcomes and safety of treating the nasolabial fold area with tissue fillers. We conducted a systematic review of randomized clinical trials that report outcomes concerning treatment of nasolabial fold area with tissue fillers. We searched the MEDLINE/PubMed, ScienceDirect, EMBASE, BIOSIS, SciELO, Scopus, Cochrane Controlled Register of Trials, CNKI and Web of Science databases. Primary outcomes included aesthetic improvement measured using the Wrinkle Severity Rating Scale score and Global Aesthetic Improvement Scale. Secondary outcomes were incidence rates of complications occurring after the procedure. At baseline, the pooled mean WSRS score was 3.23 (95% CI: 3.20–3.26). One month after the procedure, the pooled WSRS score had reached 1.79 (95% CI: 1.74–1.83). After six months it was 2.02 (95% CI: 1.99–2.05) and after 12 months it was 2.46 (95% CI: 2.4–2.52). One month after the procedure, the pooled GAIS score had reached 2.21 (95% CI: 2.14–2.28). After six months, it was 2.32 (95% CI: 2.26–2.37), and after 12 months, it was 1.27 (95% CI: 1.12–1.42). Overall, the pooled incidence of all complications was 0.58 (95% CI: 0.46–0.7). Most common included lumpiness (43%), tenderness (41%), swelling (34%) and bruising (29%). Tissue fillers used for nasolabial fold area treatment allow achieving a satisfying and sustainable improvement. Most common complications include tenderness, lumpiness, swelling, and bruising.

Level of Evidence II

"This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors  www.springer.com/00266."

Supplementary Information

The online version contains supplementary material available at 10.1007/s00266-021-02439-5.

Ultrasonography Analysis of Vessels Around the Forehead Midline

BACKGROUND

Filler injection into the glabella is well known to be a highly dangerous procedure due to the high risk of embolism and intravascular injection. Although it is conventional practice to insert the cannula into the middle of the forehead to perform injections into the glabella or radix, vascular structures can be observed in this region during anatomic dissection procedures.

OBJECTIVES

The aim of this study was to characterize the blood vessels around the forehead midline in order to provide crucial anatomic information for ensuring the safety of noninvasive procedures involving the forehead and glabella.

METHODS

Ultrasonography image scanning was performed at the following 4 points on the forehead midline: trichion (P1), metopion (P2), halfway point between metopion and glabella (P3), and glabella (P4). The courses and locations of vessels were identified and classified according to their proximity to the forehead midline.

RESULTS

Vessels coursing within 0.75 cm either side of the forehead midline were found in 34% to 50% of individuals. Arteries running near the forehead midline tended to be dominant on the right side of the forehead except in the P4 area. About half of the individuals had vessels in the P4 area, of which 96.7% were veins.

CONCLUSIONS

The present results indicate that there are superficial vessels running close to the midline of the forehead. This anatomic information can explain the higher incidence of vascular complications during conventional aesthetic procedures. To ensure safety, the cannula entry point or needle puncture point for glabella augmentation should be reconsidered.

The Usefulness of Magnetic Resonance Angiography to Analyze the Variable Arterial Facial Anatomy in an Effort to Reduce Filler-Associated Blindness: Anatomical Study and Visualization Through an Augmented Reality Application

BACKGROUND

The use of soft tissue fillers for facial rejuvenation is increasing rapidly and the complications, unfortunately, follow the same path. Blindness caused by intravascular filler injections is a rare but devastating complication. Knowledge of the individual arterial anatomy may aid the injector in avoiding injecting into an artery and thus to prevent blindness.

OBJECTIVES

To evaluate if the use of magnetic resonance angiography (MRA) may visualize the arterial facial anatomy in a contrast- and radiation-free way and study the individual arterial variations using an augmented reality (AR) image.

METHODS

The individual arterial anatomy of the 3 terminal branches of the ophthalmic artery (supraorbital [SO]; supratrochlear [STr]; and dorsal nasal [DN] arteries) of 20 volunteers was studied by a 3-Tesla MRI, combining infrared (IR) facial warming and 3-dimensional time-of-flight multiple overlapping thin slab acquisition MRA. The resulting visualization of the facial arteries was shown on the patient's face through AR technology.

RESULTS

The MRA was able to visualize the SO in 90.0%, STr in 92.5%, and DN arteries in 75% of the examined patients, as well as numerous variations in both vessel localization and path. Furthermore, a proof-of-concept of the AR visualization of the individual arterial anatomy was successfully implemented.

CONCLUSIONS

Dermal filler injectors should be aware of the risk of filler-induced blindness and familiarize themselves with the visualization of the variable facial vascular anatomy. The implementation of a one-time MRA and subsequent AR visualization may be useful in the accurate planning of minimally invasive facial rejuvenation procedures.

The Immunogenicity of Hyaluronic Fillers and Its Consequences

Hyaluronic acid (HA) is a glycosaminoglycan, a natural component of the extracellular matrix. The identical structure of the molecule in all living organisms is its main advantage, as it translates into the minimal probability of immunogenicity. Therefore, it is the closest to the ideal preparation used as a filler, due to its biocompatibility and stability at the site of implantation. This paper includes the discussion of the potential mechanisms of adverse immune reactions to HA along with the mechanisms of reaction following vaccinations against SARS-CoV-2. Based on the literature, we tried to systematize adverse immune reactions with systemic manifestations to HA. The occurrence of unpredictable reactions to hyaluronic acid indicates that they may not be treated as neutral or non-allergenic. The modifications of the chemical structure of HA, additives and individual tendencies in a patient may be the cause of unpredictable reactions, leading to serious health consequences. Preparations of unknown origin, poorly purified, or including bacterial DNA are particularly dangerous. Therefore, long-lasting follow-up of the patient and the selection of a preparation approved by the FDA or EMA are of high importance. Patients are often unaware of the consequences of cheaper procedures performed by persons without suitable knowledge with the use of unregistered products, so the public should be educated and legal regulations should be introduced.

Rhinoplasty With Hyaluronic Acid: A Standard 5-step Injection Procedure Using Sharp Needle

OBJECTIVE

To explore the clinical effect of rhinoplasty with a standard 5-step injection procedure of hyaluronic acid using sharp needle in correction of deficient features of the Chinese nose.

METHODS

Between January 2016 and December 2018, hyaluronic acid was injected with the sharp needle by a standard procedure in the anterior nasal spine, nasal columella, nasal tip, nasal root, and dorsum, as well as the junction region of nasal root and brow in 198 Chinese patients. The postoperative curative effect was analyzed, and the adverse reactions were observed.

RESULTS

The nasal shape in all patients was significantly improved, obtaining the stereoscopic appearance, and satisfactory results. During a 6-month follow-up, 4 patients developed local subcutaneous congestion and bruising in the nasal dorsum after treatment, which disappeared within 2 weeks. No patients suffered from complications such as infection, embolism, necrosis, transparent nasal dorsum, and widened nasal roots.

CONCLUSIONS

Injection of hyaluronic acid with the sharp needle by a standard 5-step procedure is a safe technique that can effectively correct the deficient features of the Chinese nose.

Impact of Minimally Invasive Aesthetic Procedures on the Psychological and Social Dimensions of Health

Background:

The impact on psychosocial health of injectable facial treatments such as hyaluronic acid fillers and botulinum toxin type A remains poorly defined. The aim of this study was to measure changes in psychosocial health following aesthetic intervention with injectables in routine clinical practice using the validated FACE-Q patient-reported outcome measure.

Methods:

This was a prospective assessment of patients presenting at a single center for the first time for aesthetic treatment of the face with injectables in February 2020. Participants completed 3 FACE-Q scales at the baseline and again 2 weeks posttreatment: Psychological Function; Social Function; and Appearance-related Psychosocial Distress.

Results:

Complete data were available for 35 individuals (n = 32 women [91%]; mean age: 45.9 ± 13.8 years). Twenty-nine (83%) were treated with hyaluronic acid filler (mean: 2.3 ± 1.3 syringes), and 12 (34%) received onabotulinumtoxinA (mean: 2.0 ± 0.7 areas of the upper face). There were significant improvements on each FACE-Q scale posttreatment: mean change in Psychological Function score was +12.4 [95% CI: 7.9, 16.9; P < 0.001; standardized effect size by Cohen’s d: 0.93]; mean change in Social Function score was +7.9 (95% CI: 3.3, 12.5; P = 0.001; effect size: 0.50); and mean change in Appearance-related Psychosocial Distress score was –20.9 (95% CI: –27.4, –14.3; P < 0.001; effect size: 1.27).

Conclusions:

Aesthetic treatment with injectables was associated with significant improvements in patient-reported psychological and social functioning and reductions in appearance-related distress. This change underlines the value of these therapies for improving psychosocial health in well-selected patients.

Visualization techniques of the facial arteries

BACKGROUND

As the face is known for its extreme variation in vascular anatomy and the number of filler-associated complications due to intra-arterial injection is increasing, we are in need of a method to visualize anyone's individual arterial anatomy of the face in a completely harmless way.

AIMS

The different medical imaging methods and a recently developed MRA protocol are reviewed.

METHODS

The literature of the last twenty years-with special attention for the last five years-concerning the different medical imaging modalities of the facial arteries was reviewed.

RESULTS

A harmless visualisation of the facial arteries is currently only possible with US or MRA. US may identify single vessels but never the complete arterial network. A combination of IR "heat enhancement" and a MRA 3D-TOF sequence might make it feasible to visualize a large number of facial arteries in a risk-free, radiation-free, contrast-free and non-invasive way.

CONCLUSION

Currently, a new combination of IR "heat enhancement" and a MRA 3D-TOF sequence might be the only method to visualize a large number of facial arteries.

Xanthelasma palpebrarum after hyaluronic acid injection in the lower eyelid: A case report and review of the literature

BACKGROUND

Hyaluronic acid filler treatments are a very popular nonsurgical procedure worldwide, most wanted to create a more attractive profile and correct facial aging. Since its usage has expanded, more complications have been seen.

AIMS

To report a probably new adverse effect related to injectable fillers.

PATIENT

A 38-year-old white woman who underwent hyaluronic acid filling in the periorbital area and presented twelve months after with two symmetrically yellowish plaque lesions on the lower eyelids, with no edema or nodules.

RESULTS

The lesion appeared to be xanthelasma, in a patient with no history of hyperlipidemia. Histological analysis showed unspecific findings with rare histiocytes present in the papillary dermis. The patient was treated with hyaluronidase infiltration in both lower eyelid areas as an attempt to minimize the appearance of the lesions, with a satisfactory response.

CONCLUSIONS

As hyaluronic acid fillings are becoming more popular, all physicians have to be aware of its complications. The xanthelasma-like reaction is probably a new adverse effect related to injectable fillers and it is important to be alert to this possibility.

Comparison between hyaluronic acid filler and botulinum toxin type A in the treatment of thyroid upper eyelid retraction

Purpose:

The aim of this study was to compare between hyaluronic acid filler (HA) and botulinum toxin type A (BTX-A) in the treatment of thyroid upper eyelid retraction.

Study design:

This was a prospective comparative study.

Methods:

A total of 50 eyes with upper thyroid eyelid retraction were divided into 2 groups. Each group included 25 eyes, (a) hyaluronic acid filler (HA) group: received subconjunctival HA injection and (b) botulinum toxin (BTX-A) group: received subconjunctival botulinum toxin type A injection. Full ophthalmic examination and thyroid profile were done. Marginal reflex distance 1 (MRD1) and total palpebral fissure height (TPFH) were measured before and after injection weekly for 6 months.

Results:

There is no significant difference between the two groups regarding MRD1 till the 10th week of follow up, then it became significant from the 11th to 15th week with better results in HA filler group, then the difference between the two groups become highly significant from the 16th week afterward with better results for the HA filler over the BTX-A. With regard to TPFH, there were significant differences between the BTX-A group and the HA group with a better result in BTX-A group in the first 8 weeks. Then the difference became insignificant till the 18th week. Then the difference became significant from the 19th till the 24th week with a better result in HA group.

Conclusion:

HA filler has better result in treating thyroid upper eyelid retraction than BTX-A due to its predictable controllable effect, also, due to the longer duration of action and fewer side effects.

Establishing a Standardized Facial Cosmetic Preinjection Safety Tool: The ACIST

In the past 20 years, the American population has seen an increased demand for nonsurgical minimally invasive facial rejuvenation solutions for the aging process. This widespread and increased demand for cosmetic injections brings a greater propensity for complications and adverse events. Choosing suitable patients for dermal filler is essential, as is concrete knowledge of the factors related to adverse events; however, there was no standardized tool to facilitate this process. The Joint Commission's Universal Safety checklist tools have been integrated into hospital surgical operating rooms and ambulatory outpatient settings across America and internationally and have successfully reduced errors in patient safety and outcomes. This article establishes the importance of integrating the Assessment Cosmetic Injection Safety Tool (ACIST), a standardized preinjection safety tool, into the cosmetic practice to decrease the incidence of adverse events associated with dermal filler and to achieve optimal patient satisfaction and outcomes. The ACIST was designed from the scientific literature, piloted at an urban cosmetic practice in the southern United States, finalized on the basis of feedback from participating staff members at the pilot study center, and disseminated to cosmetic nurse injectors.

Safety Assessment of High- and Low-Molecular-Weight Hyaluronans (Profhilo®) as Derived from Worldwide Postmarketing Data

Background

At present, dermal fillers based on hyaluronic acid (HA) represent the most popular intervention of dermoesthetic medicine for the treatment of skin aging. Recent studies have shown that the combination of HA chains of different lengths and molecular weights improves tissue repair and regeneration through a synergistic mechanism. Profhilo® is a product available that has been on the market since 2015 and is based on stable, hybrid, and cooperative complexes (HyCoCos) produced by means of NAHYCO® Hybrid Technology, which is an innovative thermal process that rules out the use of any chemical reagents. The result is a filler with high biocompatibility and low viscosity that favors optimal diffusion at the tissue level to obtain the target bioremodeling of the facial contour. The objective of this review is to provide data from the overall postmarketing experience after 3 years of use and more than 40,000 patients treated with the medical device.

Methods

All spontaneous postmarketing adverse event (AE) reports received from physicians and healthcare professionals worldwide between February 9, 2015, and February 8, 2018, associated with the use of the studied medical device and sent to the IBSA global safety database were analyzed.

Results

In total, 12 adverse event reports were logged in the global database, and none were considered serious. Early-onset injection site reactions, i.e., swelling, edema, redness, ecchymosis, and erythema, were the most frequently observed. Late-onset local reactions (e.g., swelling, nodules) followed. The genesis of these reactions was considered, both by the reporting physician and IBSA, as being local reactions of hypersensitivity and/or due to inappropriate injection techniques. In no case was the product held liable for direct damage. All events resolved without any complications according to the treatment guidelines. Two late-onset reactions were collected.

Conclusions

Although underreporting of minor events cannot be ruled out, the overall number of reports is very low, thereby supporting the high tolerability and safety of the product. After 3 years of postmarketing experience, the safety profile of the studied medical device is favorable and consistent with the product information.

Legal vs. illegal injectable fillers: The adverse effects comparison study

BACKGROUND

Over the past decades, soft-tissue filler injections have become an essential part of cosmetic practice worldwide. Due to the increasing demand, unlicensed practitioners venture in performing this minimally invasive procedure, injecting illegal fillers that pose serious complications.

OBJECTIVES

To compare the adverse effects of legal and illegal soft-tissue fillers injected by licensed and unlicensed practitioners.

MATERIALS AND METHODS

A 10-year retrospective, descriptive, single-center study conducted at the outpatient dermatology department and skin laser center at Siriraj Hospital from January 2009 to December 2019. Patients were identified as having treatment-related complications. Their demographic data, clinical history, and injection history were reviewed.

RESULTS

Forty patients with mean age of 37 years old were included in the study. Thirty-five of them (87.5%) were female. Illegal soft-tissue fillers were used in 28 patients (70%) and were performed by unlicensed practitioners (18 cases, 64.3%, P = .001). Adverse effects from illegal fillers (26 cases, 92.9%) developed longer than legal fillers (7 cases, 58.3%) (P = .017). Symptoms significantly lasted longer in patients injected with illegal fillers, 10 (0.07-288) weeks, as compared to patients injected with legal fillers 0.75 (0.14-72) weeks (P = .01). Injections from illegal fillers resulted to foreign body reaction (22 cases, 78.6%) and infections (6 cases, 21.4%). Vascular complications were identified in legal fillers injections (5 cases, 41.7%).

CONCLUSIONS

The incidence of adverse effects and complications from soft-tissue filler injections are superior when performed by novice injectors and unlicensed practitioners using illegal fillers. Proper training of filler injections, selection of appropriate fillers, and early recognition of adverse effects are critically important to the success of treatments.

Infrared Thermally Enhanced 3-Dimensional Time of Flight Magnetic Resonance Angiography Imaging for the Visualization of the Arteries of the Face

Background

The face is known for its extreme variation in vascular anatomy. Furthermore, the rapidly increasing number of filler treatments leads to an increase in severe filler-associated complications (such as skin necrosis and blindness) due to intra-arterial injection. Visualizing a patient’s individual complete facial arterial anatomy in a contrast- and radiation-free way has not been published before. This innovative imaging technique could, therefore, enhance the safety of minimally invasive surgical procedures as it provides a harmless way to map the arteries of the face.

Objectives

Evaluate a newly developed imaging technique to visualize the arteries of the face in a noninvasive and radiation-free manner.

Methods

The individual arterial facial anatomy of 20 volunteers was studied by an imaging technique, combining infrared (IR) facial warming and 3-dimensional (3D) time of flight (TOF) magnetic resonance angiography (MRA). The source and maximum intensity projection images were assessed by 2 investigators, familiar with the anatomy of the face.

Results

The MRA technique visualized most of the main facial arteries, albeit in a variable way. The main facial branches of the external carotid artery (facial, angular, supralabial, and superficial temporal arteries) were illustrated well, whereas the visualization of the internal carotid branches (supratrochlear and supraorbital arteries) and nasal branches (dorsal nasal and lateral nasal arteries) was less consistent.

Conclusions

The combination of IR “heat-induced enhancement” and a 3D-TOF MRA sequence may actually be an important step toward the visualization of the variable facial vascular anatomy in a noninvasive, radiation-free, and contrast-free manner.

Side effects and complications of injection laryngoplasty for treatment of congenital type 1 laryngeal clefts

INTRODUCTION

Injection laryngoplasty (IL) is a brief, minimally invasive procedure involving injection of agents to augment the interarytenoid space. It was initially described as a diagnostic and temporizing measure for management of type one laryngeal clefts (LC1) and associated swallowing dysfunction (SwD), but more gradually it is being proposed as a definitive treatment modality. However, the morbidity of this treatment for LC1 remains under-investigated. This study sought to determine the morbidities associated with IL as a treatment modality for LC1 and associated SwD.

METHOD

Single centre retrospective review of a prospective surgical database of one Pediatric Otolaryngologist at a tertiary care center. Participants included pediatric patients with an endoscopic diagnosis of LC1, treated with IL between 2000 and 2018-excluding those with concurrent upper airway anomalies. Patient charts were reviewed for demographic information, immediate post-op complications (within the first 14 days following IL), and subsequent management.

RESULTS

Out of 85 consecutive, eligible patients, 12 were excluded (5 subglottic stenosis, 6 laryngomalacia, and one tracheomalacia). Of the 73 included patients, 42 were male and 31 females. The median age at IL was 29 months (range 1-132, interquartile range of 38 months). All IL procedures in this study utilized hyaluronic acid derivatives. From this series, 13 patients experienced post-operative complications. The complications encountered were respiratory distress (N = 5), croup-like cough (N = 6), and stridor (N = 6). These complications were either self-limiting (N=9), managed by systemic or inhaled steroids (N = 4), or admitted to hospital for monitoring (N=3). One case (augmented with dextranomer and hyaluronic acid) required intubation, repeat endoscopy, and drainage of seroma.

CONCLUSION

IL was followed by respiratory morbidity in nearly two in ten of this series of consecutive patients. All the morbidities occurred in association with one injection product. Parents should be counselled appropriately about potential morbidities associated with this procedure.

HA-based dermal filler: downstream process comparison, impurity quantitation by validated HPLC-MS analysis, and in vivo residence time study

The success of hyaluronic acid (HA)-based dermal fillers, with more than 2 million minimally invasive procedures conducted in 2016 in the US alone, is due to their hygroscopic properties of biocompatibility and reversibility. The type and density of HA cross-linkage, as well as the manufacturing technology, may influence not only the in vivo persistence but also the safety profile of dermal fillers. 1,4-Butanediol diglycidyl ether (BDDE) is the cross-linker used in most market-leading HA fillers; 1,4-butanediol di-(propan-2,3-diolyl) ether (BDPE) is the major impurity obtained from the HA-BDDE cross-linking (HBC) process. In this work, a new process to obtain high purity HBC fillers was developed. A new HPLC-MS method was validated for the quantification of BDPE content in HBC dermal fillers. In vitro cytotoxicity of BDPE was evaluated in fibroblasts (IC₅₀ = 0.48 mg/mL). The viscoelasticity was monitored during the shelf-life of the HBC-10% hydrogel and was correlated with in vitro hyaluronidase resistance and in vivo residence time in a rabbit model. This analysis showed that elasticity is the best parameter to predict the in vivo residence time. Finally, a series of parameters were investigated in certain marketed dermal fillers and were compared with the results of the HBC-10% hydrogel.

Establishing a Standardized Facial Cosmetic Preinjection Safety Tool: The ACIST

In the past 20 years, the American population has seen an increased demand for nonsurgical minimally invasive facial rejuvenation solutions for the aging process. This widespread and increased demand for cosmetic injections brings a greater propensity for complications and adverse events. Choosing suitable patients for dermal filler is essential, as is concrete knowledge of the factors related to adverse events; however, there was no standardized tool to facilitate this process. The Joint Commission's Universal Safety checklist tools have been integrated into hospital surgical operating rooms and ambulatory outpatient settings across America and internationally and have successfully reduced errors in patient safety and outcomes. This article establishes the importance of integrating the Assessment Cosmetic Injection Safety Tool (ACIST), a standardized preinjection safety tool, into the cosmetic practice to decrease the incidence of adverse events associated with dermal filler and to achieve optimal patient satisfaction and outcomes. The ACIST was designed from the scientific literature, piloted at an urban cosmetic practice in the southern United States, finalized on the basis of feedback from participating staff members at the pilot study center, and disseminated to cosmetic nurse injectors.

Use of handheld ultrasound Doppler to prevent complications from intra-arterial injection of dermal fillers: Clinical experience

A handheld 2 MHz ultrasound Doppler device determines the presence or absence of pulsatile arterial flow immediately beneath the selected site of entry for dermal filler injection. In combination with near infrared technology to map out superficial veins, mishaps from intravascular injections may be reduced. A total of 448 patients aged range between 21 and 74 years, with 168 out of total of 1019 treatment sites having both infrared and ultrasound Doppler assisted preinjection mapping were reviewed. The injection technique is described. Improved patient safety and reduced bruising from asthetic dermal filler injections are potential benefits.

Autologous platelet-rich gel for facial rejuvenation and wrinkle amelioration: A pilot study

BACKGROUND

The demand for safe and minimally invasive soft tissue augmentation procedures has increased. Recently, a novel injectable gel based on the autologous platelet rich in growth factor (PRGF) technology has been developed to provide long-term shape and volume stability. It can be customized into low (LVG) or high viscosity (HVG) gel forms to meet different dermatological requirements.

OBJECTIVES

The mechanical and biological properties of both gel forms have been evaluated. The clinical efficacy and safety of this autologous procedure were also evaluated.

METHODS

Growth factor content and biomechanical properties of both gel forms were determined. The in vitro biological capacity on human dermal fibroblasts proliferation was assessed. Clinical performance analysis over ten patients was evaluated by standardized macrophotographs, 3D topographic images, and ultrasound analysis over periocular and nasolabial areas.

RESULTS

Both gel types showed similar growth factor concentration. HVG showed a higher stiffness profile indicating its suitability for deeper tissue defect viscosupplementation while LVG showed optimal rheologic characteristics for superficial volumization. Both gels showed a noticeable biostability after catalytic enzyme degradation. Both forms significantly increased the mitogenic activity of dermal fibroblasts. All patients referred to be highly satisfied and presented optimal clinical results after one month. Overall clinical improvement was maintained for 16 weeks. At the end of the study, the ultrasound examination revealed a cutaneous regenerative effect. No adverse events occurred.

CONCLUSIONS

This preliminary study suggests that autologous platelet gels have desirable mechanical and bioactive properties and allows moderate wrinkle reduction and efficient facial volume reposition with natural results.

Complication Management following Rejuvenation Procedures with Hyaluronic Acid Fillers-an Algorithm-based Approach

BACKGROUND

Hyaluronic acid is an ideal facial filler, however, although established as both safe and effective, complications do occur. Treatment recommendations that combine both expert opinions and clinical trial data are currently lacking, partly due to difficulties with diagnoses, nonspecific diagnostic investigations, and certain disorders presenting with similar symptoms, thereby confounding diagnosis and treatment.

METHODS

The purpose of this article was to provide the aesthetic clinician with practical recommendations regarding complication diagnosis arising as a consequence of hyaluronic acid filler rejuvenation treatment. It also provides recommendations for their management using step-wise treatment algorithms that are based on published expert opinions, as well as the author's clinical experience.

RESULTS

Algorithms are provided for the most common categories of complication associated with hyaluronic acid filler treatment, that is, skin discoloration, edema, nodules, infection, and vascular compromise.

CONCLUSIONS

These guidelines are not intended to be complete or exhaustive but may prove informative for aesthetic clinicians who are responsible for treating patients with hyaluronic acid fillers. It may help to guide them on recognizing potential complications and it provides clear guidance on optimum treatment pathways.

Severe vision loss caused by cosmetic filler augmentation: Case series with review of cause and therapy

Hyaluronic acid (HA) injection is a popular nonsurgical, facial rejuvenating procedure. Due to the rapidly expanding use of HA injections, significant potential complications have also increased in frequency. Among these complications, the rare but most devastating one is arterial occlusion, which can result in skin necrosis or blindness. To describe the mechanisms behind vision loss secondary to hyaluronic acid injection and the efficacy of treatments to restore vision and associated ocular functionality. We reviewed six cases of patients from October 2011 to December 2017 who experienced vision loss after receiving facial HA injections and the subsequent treatments undertaken to attempt to reverse the vision loss and additional eye complications. Of the six patients, four received nose, one received forehead, and another one received temple injections. All six patients developed vision loss secondary to hyaluronic acid embolization in retinal or ophthalmic arteries. Additional complications included severe periorbital pain, ptosis, impairment of extraocular muscle functionality. Recovery of vision was dependent on the type, frequency, and duration of subsequent treatment. Vision loss is a rare but catastrophic complication caused by hyaluronic injection that occurs secondary to hyaluronic acid embolization in retinal or ophthalmic arteries due to retrograde flow from facial vascular anastomoses. We suggest the early supratrochlear/supraorbital hyaluronidase injection, ocular massage, and re-breathing into a plastic bag as safe, uncomplicated and effective methods to restore the retinal circulation and reverse vision loss.

Update on injectables in the nose

PURPOSE OF REVIEW

The use of injectable fillers for nonsurgical rhinoplasty has increased tremendously over the past decade. This review describes the most commonly used fillers and their indications in the context of recent reports of both their successes and failures.

RECENT FINDINGS

Hyaluronic acid and calcium hydroxylapatite are the two most commonly used fillers for injection. Recent studies have found that most injectable fillers are met with success and patient satisfaction, but vascular complications are still a serious problem of which physicians should be wary.

SUMMARY

Injectable fillers should continue to be considered for patients on a case-by-case basis, but physicians should be knowledgeable of the various filler types, their indications, and injection technique to prevent serious complications.

Methods To Assess Shear-Thinning Hydrogels for Application As Injectable Biomaterials

Injectable hydrogels have gained popularity as a vehicle for the delivery of cells, growth factors, and other molecules to localize and improve their retention at the injection site, as well as for the mechanical bulking of tissues. However, there are many factors, such as viscosity, storage and loss moduli, and injection force, to consider when evaluating hydrogels for such applications. There are now numerous tools that can be used to quantitatively assess these factors, including for shear-thinning hydrogels because their properties change under mechanical load. Here, we describe relevant rheological tests and ways to measure injection force using a force sensor or a mechanical testing machine toward the evaluation of injectable hydrogels. Injectable, shear-thinning hydrogels can be used in a variety of clinical applications, and as an example we focus on methods for injection into the heart, where an understanding of injection properties and mechanical forces is imperative for consistent hydrogel delivery and retention. We discuss methods for delivery of hydrogels to mouse, rat, and pig hearts in models of myocardial infarction, and compare methods of tissue postprocessing for hydrogel preservation. Our intent is that the methods described herein can be helpful in the design and assessment of shear-thinning hydrogels for widespread biomedical applications.