Effect of Loading Changes on the Intraventricular Pressure Measured by Color M-Mode Echocardiography in Rats

Differences in the Impact of Left Ventricular Outflow Tract Obstruction on Intraventricular Pressure Gradient in Feline Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a common form of cardiomyopathy in cats, and heart failure occurs as diastolic dysfunction progresses. HCM in cats is broadly classified as non-obstructive and obstructive hypertrophic cardiomyopathy, depending on the presence or absence of outflow tract obstruction. Measurement of the intraventricular pressure differences (IVPD) using color M-mode (CMM) has attracted attention as a reliable diastolic index as it correlates with catheterization, the gold standard for the assessment of diastolic performance. Because IVPD is affected by the size of the heart, the intraventricular pressure gradient (IVPG) index, which is unaffected by heart size, is by calculated by dividing IVPD by LV length. In the present study, CMM IVPG was used to non-invasively assess diastolic impairment in cats with obstructive hypertrophic cardiomyopathy. This study was conducted on 10 control cats and 18 cats in the HCM group. Although no severe left atrial enlargement was observed in the HCM group, the basal IVPG was significantly increased in the HOCM group compared to the control group. Although IVPD typically suggests impaired diastolic function and reduced ventricular compliance, the significant increase observed in the HOCM group compared to controls may suggest an indirect elevation in left atrial pressure, likely secondary to left ventricular outflow tract obstruction. The increase in IVPG in HOCM, as shown in this study, is a pathological effect of left ventricular outflow tract obstruction that cannot be detected by conventional echocardiographic indices, and evaluating IVPG is useful to evaluate cardiac function from a perspective that differs from conventional methods.

Sensitive detection of hemodynamic changes after fetoscopic laser photocoagulation by assessing intraventricular pressure difference in fetuses with twin-to-twin transfusion syndrome

OBJECTIVES

To assess the hemodynamics of twin-to-twin transfusion syndrome (TTTS), we measured the intraventricular pressure difference (IVPD), a sensitive marker of myocardial diastolic function, using fetal echocardiography.

METHODS

We included 28 monochorionic diamniotic (MD) twins diagnosed with TTTS who underwent fetoscopic laser photocoagulation (FLP) between 2018 and 2022. Color M-mode Doppler images of both cardiac ventricles were obtained before and after FLP. According to this evaluation, the IVPDs were divided into three groups; those with total, basal, and mid-apical IVPD.

RESULTS

Of the 28 twins, 21 were available for analysis (including eight, eight, three, and two cases in stages Quintero Ⅰ, Ⅱ, Ⅲd, and Ⅲr, respectively). Comparing the pre and postFLP results, significant increases in total and mid-apical IVPD in the left ventricle (LV) of recipient twins were noted (total and mid-apical IVPD: p=0.026 and 0.013, respectively). In the LV of the donor twins, all IVPDs were significantly increased after FLP (total, basal, and mid-apical IVPD: p=0.003, 0.001, and 0.022, respectively). In addition, comparisons between the donor and recipient groups did not show significant differences in either ventricle before FLP.

CONCLUSIONS

IVPD detected subtle hemodynamics changes, such as volume overload and diastolic dysfunction in TTTS before and after FLP. Therefore, IVPD may be a useful marker for monitoring myocardial diastolic function in TTTS.

Assessment of anthracycline-induced cardiotoxicity in childhood cancer survivors during long-term follow-up using strain analysis and intraventricular pressure gradient measurements

BACKGROUND

Cardiac dysfunction due to cardiotoxicity from anthracycline chemotherapy is a leading cause of morbidity and mortality in childhood cancer survivors (CCS), and the cumulative incidence of cardiac events has continued to increase. This study identifies an adequate indicator of cardiac dysfunction during long-term follow-up.

PROCEDURE

In total, 116 patients (median age: 15.5 [range: 4.7-40.2] years) with childhood cancer who were treated with anthracycline were divided into three age groups for analysis (C1: 4-12 years of age, C2: 13-18 years of age, C3: 19-40 years of age), and 116 control patients of similar ages were divided into three corresponding groups (N1, N2, and N3). Layer-specific strains were assessed for longitudinal strain (LS) and circumferential strain (CS). The total and segmental intraventricular pressure gradients (IVPG) were also calculated based on Doppler imaging of the mitral inflow using Euler's equation.

RESULTS

Conventional echocardiographic parameters were not significantly different between the patients and controls. All layers of the LS and inner and middle layers of the basal and papillary CS in all ages and all IVPGs in C2 and C3 decreased compared to those of corresponding age groups. Interestingly, basal CS and basal IVPG in CCS showed moderate correlation and both tended to rapidly decrease with aging. Furthermore, basal IVPG and anthracycline dose showed significant correlations.

CONCLUSIONS

Basal CS and total and basal IVPGs may be particularly useful indicators of cardiotoxicity in long-term follow-up.

Non-Invasive Assessment of the Intraventricular Pressure Using Novel Color M-Mode Echocardiography in Animal Studies: Current Status and Future Perspectives in Veterinary Medicine

The assessment of diastolic function has received great interest in order to comprehend its crucial role in the pathophysiology of heart failure and for the early identification of cardiac events. Silent changes in the intraventricular flow (IVF) dynamics occur before the deterioration of the cardiac wall, although they cannot be detected using conventional echocardiography. Collective information on left ventricular (LV) pressures throughout the cardiac cycle has great value when dealing with patients with altered hemodynamics. Accurate pressure measurement inside the ventricle can be obtained by invasive methods to determine the LV diastolic pressures, which reflect the myocardial relaxation and compliance. However, catheterization is only feasible in the laboratory setting and is not suitable for clinical use due to its disadvantages. In contrast, echocardiography is simple, safe, and accessible. Color M-mode echocardiography (CMME) is an advanced cardiac evaluation technique that can measure the intraventricular pressure differences (IVPDs) and intraventricular pressure gradients (IVPGs) based on the Doppler shift of the IVF. Recently, the assessment of IVPD and IVPG has gained growing interest in the cardiovascular literature in both animal and human studies as a non-invasive method for the early diagnosis of cardiac dysfunctions, especially diastolic ones. The usability of IVPD and IVPG has been reported in various surgically induced heart failure or pharmacologically altered cardiac functions in rats, dogs, cats, and goats. This report aims to give an overview of the current studies of CMME-derived IVPD and IVPG in animal studies and its feasibility for clinical application in veterinary practice and to provide the prospects of the technique's ability to improve our understanding.

Stimuli-responsive hydrogels: smart state of-the-art platforms for cardiac tissue engineering

Biomedicine and tissue regeneration have made significant advancements recently, positively affecting the whole healthcare spectrum. This opened the way for them to develop their applications for revitalizing damaged tissues. Thus, their functionality will be restored. Cardiac tissue engineering (CTE) using curative procedures that combine biomolecules, biomimetic scaffolds, and cells plays a critical part in this path. Stimuli-responsive hydrogels (SRHs) are excellent three-dimensional (3D) biomaterials for tissue engineering (TE) and various biomedical applications. They can mimic the intrinsic tissues' physicochemical, mechanical, and biological characteristics in a variety of ways. They also provide for 3D setup, adequate aqueous conditions, and the mechanical consistency required for cell development. Furthermore, they function as competent delivery platforms for various biomolecules. Many natural and synthetic polymers were used to fabricate these intelligent platforms with innovative enhanced features and specialized capabilities that are appropriate for CTE applications. In the present review, different strategies employed for CTE were outlined. The light was shed on the limitations of the use of conventional hydrogels in CTE. Moreover, diverse types of SRHs, their characteristics, assembly and exploitation for CTE were discussed. To summarize, recent development in the construction of SRHs increases their potential to operate as intelligent, sophisticated systems in the reconstruction of degenerated cardiac tissues.

Effect of trehalose on heart functions in rats model after myocardial infarction: assessment of novel intraventricular pressure and heart rate variability

Background

Myocardial infarctions remain a leading cause of global deaths. Developing novel drugs to target cardiac remodeling after myocardial injury is challenging. There is an increasing interest in exploring natural cardioprotective agents and non-invasive tools like intraventricular pressure gradients (IVPG) and heart rate variability (HRV) analysis in myocardial infarctions. Trehalose (TRE), a natural disaccharide, shows promise in treating atherosclerosis, myocardial infarction, and neurodegenerative disorders.

Objectives

The objective of this study was to investigate the effectiveness of TRE in improving cardiac functions measured by IVPG and HRV and reducing myocardial remodeling following myocardial infarction in rat model.

Methods

Rats were divided into three groups: sham, myocardial infarction (MI), and trehalose-treated MI (TRE) groups. The animals in the MI and TRE groups underwent permanent ligation of the left anterior descending artery. The TRE group received 2% trehalose in their drinking water for four weeks after the surgery. At the end of the experiment, heart function was assessed using conventional echocardiography, novel color M-mode echocardiography for IVPG evaluation, and HRV analysis. After euthanasia, gross image scoring, histopathology, immunohistochemistry, and quantitative real-time PCR were performed to evaluate inflammatory reactions, oxidative stress, and apoptosis.

Results

The MI group exhibited significantly lower values in multiple IVPG parameters. In contrast, TRE administration showed an ameliorative effect on IVPG changes, with results comparable to the sham group. Additionally, TRE improved HRV parameters, mitigated morphological changes induced by myocardial infarction, reduced histological alterations in wall mass, and suppressed inflammatory reactions within the infarcted heart tissues. Furthermore, TRE demonstrated antioxidant, anti-apoptotic and anti-fibrotic properties.

Conclusion

The investigation into the effect of trehalose on a myocardial infarction rat model has yielded promising outcomes, as evidenced by improvements observed through conventional echocardiography, histological analysis, and immunohistochemical analysis. While minor trends were noticed in IVPG and HRV measurements. However, our findings offer valuable insights and demonstrate a correlation between IVPG, HRV, and other traditional markers of echo assessment in the myocardial infarction vs. sham groups. This alignment suggests the potential of IVPG and HRV as additional indicators for future research in this field.

Normative change with gestation in fetal intraventricular pressure difference with color M-mode Doppler echocardiography

AIM

The intraventricular pressure difference (IVPD) is the pressure difference in early diastole from the base to the apex of the ventricle. It is a useful marker for evaluating diastolic function because of its role as a suction force. This study investigated the changes in total and segmental IVPDs in normal fetuses throughout gestation to obtain normative data equations.

METHODS

One hundred thirty-seven healthy pregnant women at 12-40 weeks of gestation were prospectively enrolled to evaluate IVPD. The color M mode was performed, and the image was evaluated using our own code to calculate the IVPD. Segmental IVPD was divided into mid to apex and base. Pearson's correlation coefficient was used to evaluate this relationship.

RESULTS

There was a significant, positive relationship between IVPD and gestational age in both ventricles (right ventricle [RV]: r = 0.800, left ventricle [LV]: r = 0.818). As for segmental IVPD, basal and mid-apical IVPD also increased with gestation in both ventricles (RV: basal, r = 0.627; mid-apical, r = 0.705; LV: basal r = 0.758; mid-apical, r = 0.756). IVPG, which was calculated as IVPD/ventricular length, also showed a weak, positive relationship with gestation in both ventricles (RV r = 0.351, p < 0.001; LV r = 0.373, p < 0.001).

CONCLUSION

The total and segmental IVPDs significantly increased linearly through time.

Novel protocol to establish the myocardial infarction model in rats using a combination of medetomidine-midazolam-butorphanol (MMB) and atipamezole

Background

Myocardial infarction (MI) is one of the most common cardiac problems causing deaths in humans. Previously validated anesthetic agents used in MI model establishment are currently controversial with severe restrictions because of ethical concerns. The combination between medetomidine, midazolam, and butorphanol (MMB) is commonly used in different animal models. The possibility of MMB combination to establish the MI model in rats did not study yet which is difficult because of severe respiratory depression and delayed recovery post-surgery, resulting in significant deaths. Atipamezole is used to counter the cardiopulmonary suppressive effect of MMB.

Objectives

The aim of the present study is to establish MI model in rats using a novel anesthetic combination between MMB and Atipamezole.

Materials and methods

Twenty-five Sprague Dawley (SD) rats were included. Rats were prepared for induction of the Myocardial infarction (MI) model through thoracotomy. Anesthesia was initially induced with a mixture of MMB (0.3/5.0/5.0 mg/kg/SC), respectively. After endotracheal intubation, rats were maintained with isoflurane 1% which gradually reduced after chest closing. MI was induced through the left anterior descending (LAD) artery ligation technique. Atipamezole was administered after finishing all surgical procedures at a dose rate of 1.0 mg/kg/SC. Cardiac function parameters were evaluated using ECG (before and after atipamezole administration) and transthoracic echocardiography (before and 1 month after MI induction) to confirm the successful model. The induction time, operation time, and recovery time were calculated. The success rate of the MI model was also calculated.

Results

MI was successfully established with the mentioned anesthetic protocol through the LAD ligation technique and confirmed through changes in ECG and echocardiographic parameters after MI. ECG data was improved after atipamezole administration through a significant increase in heart rate (HR), PR Interval, QRS Interval, and QT correction (QTc) and a significant reduction in RR Interval. Atipamezole enables rats to recover voluntary respiratory movement (VRM), wakefulness, movement, and posture within a very short time after administration. Echocardiographic ally, MI rats showed a significant decrease in the left ventricular wall thickness, EF, FS, and increased left ventricular diastolic and systolic internal diameter. In addition, induction time (3.440 ± 1.044), operation time (29.40 ± 3.663), partial recovery time (10.84 ± 3.313), and complete recovery time (12.36 ± 4.847) were relatively short. Moreover, the success rate of the anesthetic protocol was 100%, and all rats were maintained for 1 month after surgery with a survival rate of 88%.

Conclusion

Our protocol produced a more easy anesthetic effect and time-saving procedures with a highly successful rate in MI rats. Subcutaneous injection of Atipamezole efficiently counters the cardiopulmonary side effect of MMB which is necessary for rapid recovery and subsequently enhancing the survival rate during the creation of the MI model in rats.

The Pivotal Role of Stem Cells in Veterinary Regenerative Medicine and Tissue Engineering

The introduction of new regenerative therapeutic modalities in the veterinary practice has recently picked up a lot of interest. Stem cells are undifferentiated cells with a high capacity to self-renew and develop into tissue cells with specific roles. Hence, they are an effective therapeutic option to ameliorate the ability of the body to repair and engineer damaged tissues. Currently, based on their facile isolation and culture procedures and the absence of ethical concerns with their use, mesenchymal stem cells (MSCs) are the most promising stem cell type for therapeutic applications. They are becoming more and more well-known in veterinary medicine because of their exceptional immunomodulatory capabilities. However, their implementation on the clinical scale is still challenging. These limitations to their use in diverse affections in different animals drive the advancement of these therapies. In the present article, we discuss the ability of MSCs as a potent therapeutic modality for the engineering of different animals' tissues including the heart, skin, digestive system (mouth, teeth, gastrointestinal tract, and liver), musculoskeletal system (tendons, ligaments, joints, muscles, and nerves), kidneys, respiratory system, and eyes based on the existing knowledge. Moreover, we highlighted the promises of the implementation of MSCs in clinical use in veterinary practice.

Novel color M-mode echocardiography for non-invasive assessment of the intraventricular pressure in goats: Feasibility, repeatability, and the effect of sedation

Background

The intraventricular pressure difference (IVPD) and intraventricular pressure gradients (IVPG), estimated from color M-mode echocardiography (CMME) of the transmitral flow, have been introduced as novel indices for the evaluation of heart functions. Until now, no study demonstrated the feasibility of the CMME approach to measure IVPD and IVPG in any farm animals. The aim of this study was to assess the feasibility and repeatability of CMME-derived IVPD and IVPG variables in goats and explore the effect of sedation on the measured variables.

Materials and methods

Sixteen male Shiba goats were included in this study and underwent conventional echocardiography. Eight goats were used in the repeatability of IVPD/IVPG variables. Another eight goats were used to evaluate the effect of sedation by xylazine on IVPD/IVPG measurements. CMME between the base and the apex of the left ventricle was carried out. The IVPD and IVPG were analyzed using in-house code software. The IVPD and IVPG were expressed as total, basal, mid-to-apical, mid, and apical segments. Data analysis including the imaging quality score (IQS), repeatability, variability, intraclass correlation coefficient (ICC), as well as the effect size of sedation on the measured variables was calculated.

Results

IVPD and IVPG variables from CMME were feasible in all goats. Low to moderate variability of IVPD and IVPG variables was observed (CV 95% <25%) except for the apical IVPD and apical IVPG. The IVPD/IVPG measurements were repeatable without a significant effect of animal or time on the obtained measurements. The overall ICC was higher than 0.75 in all variables except for the apical segment. Xylazine administration reduced the total, basal, and mid parts of IVPD and IVPG with a large effect size (biserial ranked correlation; rc > 0.8).

Conclusion

We reported, for the first time, IVPD and IVPG measurements by CMME in goats. The assessment of IVPD and IVPG by CMME is feasible in goats which can be evaluated in further cardiovascular or pharmacological studies in this species.

Intraventricular pressure gradient: A novel tool to assess the post-infarction chronic congestive heart failure

Congestive heart failure (CHF), the leading cause of death, is deemed a grave sequel of myocardial infarction (MI). The employment of left ventricular end-diastolic pressure (LVEDP), as a primary indication of CHF, becomes restricted owing to the potential impairment of heart function and caused injury to the aortic valve during its measurement. Echocardiography is the standard technique to detect cardiac dysfunction. However, it exhibits a low capacity to predict the progression of CHF post chronic MI. Being extremely sensitive, noninvasive, and preload-independent, intraventricular pressure gradient (IVPG) was lately introduced to evaluate cardiac function, specifically during cardiomyopathy. Yet, the utility of its use to assess the CHF progression after chronic MI was not investigated. Herein, in the current research, we aimed to study the efficacy of a novel echocardiographic-derived index as IVPG in the assessment of cardiac function in a chronic MI rat model with CHF. Fifty healthy male rats were involved, and MI was surgically induced in 35 of them. Six months post-surgery, all animals were examined using transthoracic conventional and color M-mode echocardiography (CMME) for IVPG. Animals were euthanized the following day after hemodynamics recording. Gross pathological and histological evaluations were performed. J-tree cluster analysis was conducted relying on ten echocardiographic parameters suggestive of CHF. Animals were merged into two main clusters: CHF+ (MI/HF + group, n = 22) and CHF– (n = 28) that was joined from Sham (n = 15), and MI/HF– (n = 13) groups. MI/HF+ group showed the most severe echocardiographic, hemodynamic, anatomic, and histologic alterations. There was no significant change in the total IVPG among various groups. However, the basal IVPG was significantly increased in MI/HF+ group compared to the other groups. The remaining IVPG measures were considerably increased in the MI/HF+ group than in the Sham one. The segmental IVPG measures were significantly correlated with the anatomical, histological, echocardiographic, and hemodynamic findings except for the heart rate. Moreover, they were significant predictors of CHF following a long-standing MI. Conclusively, IVPG obtained from CMME is a substantially promising noninvasive tool with a high ability to detect and predict the progression of CHF following chronic MI compared to conventional echocardiography.

Color M-Mode Echocardiography for Non-Invasive Assessment of the Intraventricular Pressure in Dogs Before and After Ductus Arteriosus Occlusion: A Retrospective Study

Background

Novel non-invasive evaluation of the intraventricular pressure differences and gradients (IVPD and IVPG) by color M-mode echocardiography (CMME) is a promising method in diastolic function evaluation. Patent ductus arteriosus (PDA) is a congenital heart defect which is associated with increased preload. The present work provides a clinical trial for the assessment of IVPD and IVPG changes in dogs before and after surgical occlusion of PDA.

Materials and Methods

A total of 12 client-owned dogs were enrolled in this study. PDA was confirmed using echocardiography, and all dogs underwent PDA occlusion. Conventional echocardiography and CMME were conducted on each patient on the operation day (Pre-PDA) and 48 h after its occlusion (Post-PDA). The total IVPD and total IVPG, as well as segmental intraventricular pressure (basal, mid-to-apical, mid, and apical) were measured from Euler's equation using specific software (MATLAB). Data were analyzed for variability and for the difference between pre- and post-PDA. The effect of PDA occlusion on the measured variables was calculated using biserial ranked correlation (rc).

Results

There was a significant reduction in end-diastolic volume, fraction shortening, stroke volume, and mitral inflow velocities (early and late) after PDA closure. CMME was feasible in all dogs, and the CMME indices showed moderate variability, except for the apical segment of IVPD and IVPG. After PDA closure, in comparison with the pre-PDA occlusion, there was a significant reduction in total IVPD (2.285 ± 0.374 vs. 1.748 ± 0.436 mmHg; P = 0.014), basal IVPD (1.177 ± 0.538 vs. 0.696 ± 0.144 mmHg; P = 0.012), total IVPG (1.141 ± 0.246 vs. 0.933 ± 0.208 mmHg; P = 0.032), and basal IVPG (0.578 ± 0.199 vs. 0.377 ± 0.113 mmHg; P = 0.001); meanwhile, mid, mid-to-apical, and apical segments of both IVPD and IVPG showed non-significant difference. The magnitude of PDA occlusion on the measured variables was clinically relevant and associated with a large effect size on total and basal IVPD and IVPG (rc > 0.6).

Conclusion

The current clinical study revealed matched response of IVPD and IVPG to the reduced preload rather than left ventricular relaxation. This result is an initial step in the clinical utility of CMME-derived IVPD and IVPG measurements in the diastolic function evaluation in dogs with PDA that warrants further clinical studies.

Changes in Cardiac Function During the Development of Uremic Cardiomyopathy and the Effect of Salvianolic Acid B Administration in a Rat Model

Background

Uremic cardiomyopathy (UC), the main cause of death in progressive chronic kidney disease (CKD), is characterized by diastolic dysfunction. Intraventricular pressure gradients (IVPG) derived from color m-mode echocardiography (CMME) and two-dimensional speckle tracking echocardiography (2DSTE) were established as novel echocardiographic approaches for non-invasive and repeatable assessment of cardiac function. Previously, salvianolic acid B (Sal B) showed the potential to alleviate concentric LV hypertrophy in the pressure overload model. The purpose of this study was to evaluate the changes in cardiac function in UC and assess the efficacy of Sal B therapy using IVPG and 2DSTE techniques.

Materials and Methods

Twenty-four rats underwent subtotal nephrectomy to produce progressive renal failure and were allocated equally into UC (n = 12) and Sal B-UC (n = 12) groups and monitored for 8 weeks. A sham-operated group was also included in this study (n = 12). Sal B was injected from weeks 4 to 8 in the Sal B-UC group. Conventional echocardiography, 2DSTE, and CMME were performed every 2 weeks post-operation, concomitantly with an evaluation of renal function. Histopathological and immunohistochemistry analyses were carried out to confirm the echocardiography findings.

Results

Renal failure and myocardial dysfunction were confirmed in the UC group from weeks 2 through 8. Eccentric and concentric hypertrophy was observed in the UC group, while the Sal B-UC group showed only eccentric hypertrophy. IVPG analysis did not reveal any significant differences between the groups. Edema, inflammation, fibrosis, and immunohistochemical expression of CD3 infiltration were higher in the UC group compared with sham and Sal B-UC groups.

Conclusion

2DSTE and IVPG explored the pathophysiology during the development of UC and indicated the incidence of myocardial dysfunction before ventricular morphological changes without intracardiac flow changes. This study confirmed increased ventricular stiffness and fibrosis in UC rats which was potentially treated by Sal B via decreasing edema, inflammation, and fibrosis.

Smart/stimuli-responsive hydrogels: Cutting-edge platforms for tissue engineering and other biomedical applications

Recently, biomedicine and tissue regeneration have emerged as great advances that impacted the spectrum of healthcare. This left the door open for further improvement of their applications to revitalize the impaired tissues. Hence, restoring their functions. The implementation of therapeutic protocols that merge biomimetic scaffolds, bioactive molecules, and cells plays a pivotal role in this track. Smart/stimuli-responsive hydrogels are remarkable three-dimensional (3D) bioscaffolds intended for tissue engineering and other biomedical purposes. They can simulate the physicochemical, mechanical, and biological characters of the innate tissues. Also, they provide the aqueous conditions for cell growth, support 3D conformation, provide mechanical stability for the cells, and serve as potent delivery matrices for bioactive molecules. Many natural and artificial polymers were broadly utilized to design these intelligent platforms with novel advanced characteristics and tailored functionalities that fit such applications. In the present review, we highlighted the different types of smart/stimuli-responsive hydrogels with emphasis on their synthesis scheme. Besides, the mechanisms of their responsiveness to different stimuli were elaborated. Their potential for tissue engineering applications was discussed. Furthermore, their exploitation in other biomedical applications as targeted drug delivery, smart biosensors, actuators, 3D and 4D printing, and 3D cell culture were outlined. In addition, we threw light on smart self-healing hydrogels and their applications in biomedicine. Eventually, we presented their future perceptions in biomedical and tissue regeneration applications. Conclusively, current progress in the design of smart/stimuli-responsive hydrogels enhances their prospective to function as intelligent, and sophisticated systems in different biomedical applications.

Evaluation of Changes in the Cardiac Function before and after Transcatheter Edge-to-Edge Mitral Valve Repair in Healthy Dogs: Conventional and Novel Echocardiography

Mitral valve regurgitation is a common canine heart disease. Transcatheter Edge-to-Edge Repair (TEER) is a transcatheter, edge-to-edge mitral repair device that uses a hybrid approach. No detailed information has been published on the hemodynamic effect of TEER on cardiac function. The aim of this report is to provide a longitudinal observation of the cardiac functional changes observed after TEER implantation in normal dogs using traditional, two-dimensional speckle tracking, and color M-mode echocardiographic methods. In the current report, TEER was implanted into two healthy dogs under general anesthesia. An echocardiographic examination was performed at baseline and weekly postoperative follow-ups were conducted until the fourth week. Successful TEER implantation was achieved with a short operation time (98 and 63 min) in the two dogs. Functional mitral valve regurgitation, elevated E/e' ratio, elevated radial strain, and stable intraventricular pressure gradients (IVPG) were observed after the operation in the dogs. Mild non progressive mitral valve stenosis was observed in both dogs. TEER is a minimally invasive method for mitral valve surgery that necessitates more clinical trials. With longitudinal observation of heart function using novel approaches, better outcomes will be expected.