Intracoronary transplantation of pluripotent stem cell-derived cardiomyocytes: Inefficient procedure for cardiac regeneration

Advances in stem cell biology have facilitated cardiac regeneration, and many animal studies and several initial clinical trials have been conducted using human pluripotent stem cell-derived cardiomyocytes (PSC-CMs). Most preclinical and clinical studies have typically transplanted PSC-CMs via the following two distinct approaches: direct intramyocardial injection or epicardial delivery of engineered heart tissue. Both approaches present common disadvantages, including a mandatory thoracotomy and poor engraftment. Furthermore, a standard transplantation approach has yet to be established. In this study, we tested the feasibility of performing intracoronary administration of PSC-CMs based on a commonly used method of transplanting somatic stem cells. Six male cynomolgus monkeys underwent intracoronary administration of dispersed human PSC-CMs or PSC-CM aggregates, which are called cardiac spheroids, with multiple cell dosages. The recipient animals were sacrificed at 4 weeks post-transplantation for histological analysis. Intracoronary administration of dispersed human PSC-CMs in the cynomolgus monkeys did not lead to coronary embolism or graft survival. Although the transplanted cardiac spheroids became partially engrafted, they also induced scar formation due to cardiac ischemic injury. Cardiac engraftment and scar formation were reasonably consistent with the spheroid size or cell dosage. These findings indicate that intracoronary transplantation of PSC-CMs is an inefficient therapeutic approach.

Cardiac Gene Delivery in Large Animal Models: Antegrade Techniques

Percutaneous antegrade coronary injection is among the least invasive cardiac selective gene delivery methods. However, the transduction efficiency of a simple bolus antegrade injection is quite low. In order to improve transduction efficiency in antegrade intracoronary delivery, several additional approaches have been proposed.In this chapter, we will describe the important elements associated with intracoronary delivery methods and present protocols for three different catheter-based antegrade gene delivery techniques in a preclinical large animal model. This is the second edition of this chapter, and it includes modifications we have made over the past several years that further enhance transduction efficacy.

[Methergin pour le diagnostic de l'angor spastique : voie intraveineuse ou intracoronaire ?]

BACKGROUND

Vasospastic angina is an infrequent underlying cause of angina and is under-diagnosed. Ergonovine provocation tests can be performed via intravenous or intracoronary injections. Although the safety profile of intracoronary injection has been well documented, no study has yet compared the intracoronary and intravenous injections regarding the positivity rate of the test.

AIMS

This study sought to compare the positivity rate of intravenous versus intracoronary injection of ergonovine in the diagnosis of vasospastic angina.

METHODS

Between January 2010 and February 2018, 427 patients with suspected vasospastic angina underwent an ergonovine provocation test in 2 tertiary hospitals in France and were retrospectively included in this study. Injection was performed via the intravenous or the intracoronary route. The primary endpoint was the positivity rate of the test. Propensity score matching was used to account for confounding factors.

RESULTS

427 patients were included in the study. Mean age was 60.3 (+/- 12.4) years. There were 247 (58%) females and 97 (23%) smokers. The intracoronary route was used in 199 (47%) patients. The indication for the test was acute coronary syndrome for 121 (28%). No rhythmic complications or deaths were reported. After propensity-matching, the baseline characteristics of the 2 groups (148 patients in each) were comparable. The positivity rate was 24% in the intracoronary group and 9% in the intravenous group (OR [95%CI]: 3.2 [1.6, 6.4]).

CONCLUSIONS

Intracoronary injection of ergonovine is safe and associated with a positivity rate of the test three times higher compared to intravenous injection.

Synergistic effects of intracoronary infusion of autologous bone marrow-derived mesenchymal stem cells and revascularization procedure on improvement of cardiac function in patients with severe ischemic cardiomyopathy

Background

Ischemic cardiomyopathy (ICM) is a leading cause of cardiovascular mortality worldwide. It is defined as abnormal enlargement of the left ventricular (LV) cavity with poor LV function due to coronary artery disease. Currently available established treatments are palliative whereby blood supply is recovered to ischemic regions but fails to regenerate heart tissues. Mesenchymal stem cells (MSCs) offer a promising treatment for ICM given their regenerative and multipotent characteristics. This study aims to investigate the effect of MSCs infusion with concurrent revascularization in patients with severe ICM compared to receiving only revascularization procedure or MSCs infusion.

Methods

Twenty-seven patients with history of anterior myocardial infarction (MI) and baseline left ventricular ejection fraction (LVEF) of less than 35% were recruited into this study. Patients who are eligible for revascularization were grouped into group A (MSCs infusion with concurrent revascularization) or group B (revascularization only) while patients who were not eligible for revascularization were allocated in group C to receive intracoronary MSCs infusion. LV function was measured using echocardiography.

Results

Patients who received MSCs infusion (either with or without revascularization) demonstrated significant LVEF improvements at 3, 6 and 12 months post-infusion when compared to baseline LVEF within its own group. When comparing the groups, the magnitude of change in LVEF from baseline for third visits i.e., 12 months post-infusion was significant for patients who received MSCs infusion plus concurrent revascularization in comparison to patients who only had the revascularization procedure.

Conclusions

MSCs infusion significantly improves LV function in ICM patients. MSCs infusion plus concurrent revascularization procedure worked synergistically to improve cardiac function in patients with severe ICM.

Epicardial Ablation via Arterial and Venous Systems

The intracoronary artery and venous routes provide unique roadmaps for mapping and interventions for ventricular arrhythmias and certain atrial arrhythmias. The unique anatomic location of these vessels on the epicardial surface enables mapping/interventions without the need to access the pericardial space. These anatomic routes also track deep into certain intramural regions, with interventions that are not accessible from either epicardial or endocardial routes. To map smaller vessels, multipolar catheters and wires are used to record local electrograms. Endocardial/epicardial ablation at adjacent sites is sometimes required to enhance successful outcomes. This article describes tools, techniques, and site-specific mapping and interventions.

Intracoronary high-dose bolus tirofiban administration during complex coronary interventions: A United States-based case series

The GP IIb/IIIa inhibitors (GPIs) rapidly provide therapeutic levels of platelet aggregation inhibition and serve as adjunct pharmacotherapy to oral P2Y12 inhibitors that exhibit a significant delay in onset of action for patients with Acute Coronary Syndrome (ACS). Intracoronary (IC) administration of the high dose bolus (HDB) tirofiban has not been extensively studied. Compared to intravenous delivery, IC administration can lead to higher local drug concentration and, therefore, provide instantaneous disruption of platelet aggregation in the culprit vessel. This report describes the successful resolution of thrombus using IC HDB tirofiban in 7 high-risk coronary interventions with complications such as recurrent thrombosis and cardiogenic shock in ACS patients. This report represents the first case series of IC HDB tirofiban performed in North America and suggests that IC HDB tirofiban may represent an effective and safe strategy to achieve rapid thrombus resolution in ACS patients.

A retrospective analysis of catheter-based sources in intravascular brachytherapy

PURPOSE

Coronary artery disease involves the deposition of plaque along the walls of a coronary artery leading to narrowed or blocked vessels (stenosis) and is one of the main causes of death in developed countries. Percutaneous transluminal coronary angioplasty (PTCA) is used to reverse stenosis. Restenosis (renarrowing) of the treated vessel is a major complication of PTCA. A metal mesh tube (stent) can be placed inside the vessel to prevent restenosis. Tissue stress incurred during PTCA and stenting can provoke neointimal cell proliferation leading to in-stent restenosis (ISR). Intravascular brachytherapy (IVBT), a form of internal radiotherapy, is used to treat ISR. Renewed interest in IVBT is being expressed as a treatment for patients with ISR in drug-eluting stents. Current treatment planning (TP) of IVBT is extremely limited and assumes human tissue can be approximated by water. The interactions of arterial plaque, guidewires, and the stent have been shown to attenuate radiation significantly but are ignored in TP. Other models have determined the degree of attenuation by each factor in isolation. For the first time, we create a model with several inhomogenities present to determine whether attenuation by multiple inhomogenities combines linearly or if a larger dose reduction than anticipated is realized. We are also able to evaluate a spatial distribution of dose around the source and in arterial walls.

METHODS AND MATERIALS

A dosimetric analysis of two commercially available IVBT systems was performed in a Monte Carlo-based particle simulation (Geant4). Absorbed dose was calculated using a model of a human coronary artery with a calcified plaque and stent. Dose delivered in water was also calculated to evaluate the accuracy of a water approximation.

RESULTS

Dose as a function of θ shows significant variation around IVBT sources. For the Guidant Galileo, dose is reduced by 20% behind stent struts and as much as 66% in a region occluded by the guidewire, plaque, and stent. For the Novoste Beta Cath device, delivered dose is reduced by 19% and 58%, respectively, in the same regions.

CONCLUSIONS

Our findings show that the water approximation used in clinical practice to calculate dose is inaccurate when inhomogeneities are present. Methods proposed for calculating dose perturbations in IVBT may underestimate the magnitude of dose reduction. Increasing source dwell time seems unlikely to resolve dosimetric issues in IVBT. The effectiveness of currently existing β-emitting devices may be reduced in patients with complex lesions at the treatment site. Investigation of new radioisotopes and off-centering devices should be considered to improve dose outcomes.

Cardiac Gene Delivery in Large Animal Models: Antegrade Techniques

Percutaneous antegrade coronary injection is among the least invasive cardiac selective gene delivery methods. However, transduction efficiency is quite low with a simple bolus antegrade injection. In order to improve the transduction efficiency using antegrade delivery, several additional approaches have been proposed.In this chapter, we briefly discuss important elements associated with intracoronary delivery methods and present protocols for three different catheter-based antegrade delivery techniques in a preclinical large animal model. Despite the lower transduction efficacy relative to more invasive delivery techniques, antegrade techniques have the advantage of being clinically well established and having safer profiles which is important when treating patients with cardiac disease.

Intracoronary adenosine-induced ventricular arrhythmias during fractional flow reserve (FFR) measurement: case series and literature review. Cardiovasc Interv Ther. 2017;32:374-380. [PMID: 27577946 DOI: 10.1007/s12928-016-0427-8]

Fractional flow reserve (FFR) is a standardized and well-established method frequently used in clinical practice to evaluate the hemodynamic significance of epicardial coronary stenosis identified by coronary angiography. It is based on the change in the pressure gradient across the stenosis after the achievement of maximal hyperemia of the coronary circulation which is commonly induced by intravenous (IV) or intracoronary (IC) administration of adenosine. Here, we have described three cases of IC adenosine-induced ventricular arrhythmias during FFR measurement from our institution, and after literature review we found that all the cases of ventricular arrhythmias induced by adenosine during FFR measurement were observed where it was administered via IC route. Although a causal relationship between the use of IC adenosine during FFR measurement and the induction of ventricular arrhythmias is not yet established, we suggest using IV adenosine as the preferred route of administration until we better understand the incidence and mechanism underlying this phenomenon.

ST elevation after intracoronary administration of Papaverine for fractional flow reserve estimation

INTRODUCTION

Intracoronary (IC) papaverine which is one of the commonly used agents for Fractional Flow Reserve (FFR) estimation has been reported to cause transient ST elevation in some patients. This phenomenon has not been systematically studied.

MATERIAL AND METHODS

This is a prospective, observational study. Consecutive patients, who underwent FFR at our institute using IC papaverine from May 2012 to April 2013, were included. FFR was done when clinically indicated. The procedure involved administration of 20 mg papaverine (Paparin)--Troikaa, Ahmedabad) as a fast bolus by intracoronary route followed by a 10 cc contrast flush, following which pressure measurements were made. Continuous ECG recording by Philips Hemodynamic Laboratory was obtained for all patients throughout the procedure. Post procedure, they were observed for any delayed effects and eventual outcome was documented. Fischer's mid-p test was used for statistical analysis.

RESULT

Twenty-five patients (18 males, 7 females, mean age 57.9 ± 20 years) underwent FFR using Papaverine. The mean LVEF was (51 ± 15%). Fourteen patients (56%) developed transient ST elevation ≥0.5 mm in one or more leads which resolved spontaneously in all cases without any sequelae. The presence of a significant lesion either in the coronary artery being evaluated or in a remote coronary artery did not predict the ST elevation. 70.5% of diabetics (p = 0.02), 75% of hypertensives (p = 0.008) and 75% of patients with LVH (p = 0.008) had ST elevation. None of the 5 patients without any one of these comorbidities showed ST elevation.

CONCLUSION

Transient ST elevation occurs in a significant proportion of cases receiving IC papaverine which is not associated with any adverse clinical outcomes. Micro vascular dysfunction is the most likely mechanism of this phenomenon.