Myocardial protection via the coronary sinus

Signs and signals limiting myocardial damage using PICSO: a scoping review decoding paradigm shifts toward a new encounter

Background

Inducing recovery in myocardial ischemia is limited to a timely reopening of infarct vessels and clearing the cardiac microcirculation, but additional molecular factors may impact recovery.

Objective

In this scoping review, we identify the paradigm shifts decoding the branching points of experimental and clinical evidence of pressure-controlled intermittent coronary sinus occlusion (PICSO), focusing on myocardial salvage and molecular implications on infarct healing and repair.

Design

The reporting of evidence was structured chronologically, describing the evolution of the concept from mainstream research to core findings dictating a paradigm change. All data reported in this scoping review are based on published data, but new evaluations are also included.

Results

Previous findings relate hemodynamic PICSO effects clearing reperfused microcirculation to myocardial salvage. The activation of venous endothelium opened a new avenue for understanding PICSO. A flow-sensitive signaling molecule, miR-145-5p, showed a five-fold increase in porcine myocardium subjected to PICSO.Verifying our theory of "embryonic recall," an upregulation of miR-19b and miR-101 significantly correlates to the time of pressure increase in cardiac veins during PICSO (r2 = 0.90, p < 0.05; r2 = 0.98, p < 0.03), suggesting a flow- and pressure-dependent secretion of signaling molecules into the coronary circulation. Furthermore, cardiomyocyte proliferation by miR-19b and the protective role of miR-101 against remodeling show another potential interaction of PICSO in myocardial healing.

Conclusion

Molecular signaling during PICSO may contribute to retroperfusion toward deprived myocardium and clearing the reperfused cardiac microcirculation. A burst of specific miRNA reiterating embryonic molecular pathways may play a role in targeting myocardial jeopardy and will be an essential therapeutic contribution in limiting infarcts in recovering patients.

Transcatheter Coronary Sinus Interventions

The coronary sinus has become a popular route for an increasing number of innovative transcatheter interventions to treat coronary and structural heart diseases. However, interventional cardiologists have limited experience with the cardiac venous system and its highly variable anatomy. In this paper, we review the anatomy of the cardiac veins as it relates to transcatheter interventions. We also provide a contemporary overview of the emerging coronary sinus-based transcatheter therapies and their growing literature.

Acute molecular effects of pressure-controlled intermittent coronary sinus occlusion in patients with advanced heart failure

Aims

Cardiac repair has steered clinical attention and remains an unmet need, because available regenerative therapies lack robust mechanistic evidence. Pressure‐controlled intermittent coronary sinus occlusion (PICSO), known to induce angiogenetic and vasoactive molecules as well as to reduce regional ischemia, may activate endogenous regenerative processes in failing myocardium. We aimed to investigate the effects of PICSO in patients with advanced heart failure undergoing cardiac resynchronization therapy.

Methods and results

Eight out of 32 patients were treated with PICSO, and the remainder served as controls. After electrode testing including left ventricular leads, PICSO was performed for 20 min. To test immediate molecular responses, in both patient groups, coronary venous blood samples were taken at baseline and after 20 min, the time required for the intervention. Sera were tested for microRNAs and growth factors. To test the ability of up‐regulated soluble factors on cell proliferation and expression of transcription factors [e.g. Krüppel‐like factor 4 (KLF‐4)], sera were co‐cultured with human cardiomyocytes and fibroblasts. As compared with controls, significant differential expression (differences between pre‐values and post‐values in relation to both patient cohorts) of microRNA patterns associated with cardiac development was observed with PICSO. Importantly, miR‐143 (P < 0.048) and miR‐145 (P < 0,047) increased, both targeting a network of transcription factors (including KLF‐4) that promote differentiation and repress proliferation of vascular smooth muscle cells. Additionally, an increase of miR‐19b (P < 0.019) known to alleviate endothelial cell apoptosis was found, whereas disadvantageous miR‐320b (P < 0.023) suspect to impair expression of c‐myc, normally provoking cell cycle re‐entry in post‐mitotic myocytes and miR‐25 (P < 0.023), decreased, a target of anti‐miR application to improve contractility in the failing heart. Co‐cultured post‐PICSO sera significantly increased cellular proliferation both in fibroblasts (P < 0.001) and adult cardiomycytes (P < 0.004) sampled from a transplant recipient as compared with controls. Adult cardiomyocytes showed a seven‐fold increase of the transcription factor KLF‐4 protein when co‐cultured with treated sera as compared with controls.

Conclusions

Here, we show for the first time that PICSO, a trans‐coronary sinus catheter intervention, is associated with an increase in morphogens secreted into cardiac veins, normally present during cardiac development, and a significant induction of cell proliferation. Present findings support the notion that epigenetic modifications, that is, haemodynamic stimuli on venous vascular cells, may reverse myocardial deterioration. Further investigations are needed to decipher the maze of complex interacting molecular pathways in failing myocardium and the potential role of PICSO to reinitiate developmental processes to prevent further myocardial decay eventually reaching clinical significance.

Coronary sinus flow is reduced in methamphetamine abusers: a transthoracic echocardiographic study

To compare the coronary sinus flow among healthy participants, methamphetamine abusers without chest pain and those with chest pain. One hundred and eight methamphetamine abusers: 53 ones without chest pain, 55 ones with chest pain, free of ascertained coronary artery disease, were enrolled in this study. A control group of 50 age-matched male healthy participants was studied for comparison. Standard 2D, flow and tissue Doppler echo with measurements of cardiac morphologic and functional indicators, coronary sinus flow, and inferior vena cava (IVC) ultrasound with measurements of the IVC dimensions and their collapsibility index were performed, respectively. Compared to healthy participants, methamphetamine abusers had higher blood pressure, greater left ventricular mass index and more impaired diastolic function, with preserved cardiac sizes, systolic function and right atrial pressure. Methamphetamine abusers with chest pain had faster heart rate than those without chest pain and healthy participants. Coronary sinus flow was significantly less in methamphetamine abusers than in healthy participants (P < 0.05), and was extremely lower in those with chest pain than in healthy participants (about one-fourth) (P < 0.01). The area under the curve (AUC) of coronary sinus flow was 0.913 (0.864-0.962), and the cutoff value with 221.65 mL/min had sensitivity of 83.4%, specificity of 87.2% and accuracy of 85.2% for differentiating methamphetamine abusers from healthy participants. While the AUC of coronary sinus flow was 0.996 (0.989-1.003), and the cutoff value with 172.59 mL/min had sensitivity of 100%, specificity of 93.3% and accuracy of 96.5% for predicting methamphetamine abusers with chest pain. Coronary sinus flow is significant reduced in methamphetamine abusers, which is maybe a good indicator for indentifying methamphetamine abusers from normal population, and for predicting methamphetamine abusers with chest pain.

From state-of-the-art cell therapy to endogenous cardiac repair

Clinical heart failure prevention and contemporary therapy often involve breaking the vicious cycle of global haemodynamic consequences of myocardial decay. The lack of effective regenerative therapies results in a primary focus on preventing further deterioration of cardiac performance. The cellular transplantation hypothesis has been evaluated in many different preclinical models and a handful of important clinical trials. The primary expectation that cellular transplants will be embedded into failing myocardium and fuse with existing functioning cells appears unlikely. A multitude of cellular formulas, access routes and clinical surrogate endpoints for evaluation add to the complexity of cellular therapies. Several recent large clinical trials have provided insights into both the regenerative potential and clinical improvement from non-regenerative mechanisms. Initiating endogenous repair seems to be another meaningful alternative to recover structural integrity in myocardial injury. This option may be achieved using a transcoronary sinus catheter intervention, implying the understanding of basic principles in biology. With intermittent reduction of outflow in cardiac veins (PICSO), vascular cells appear to be activated and restart a programme similar to pathways in the developing heart. Structural regeneration may be possible without requiring exogenous agents, or a combination of both approaches may become clinical reality in the next decade.

Coronary Sinus Flow Is Reduced and Recovered With Time in Viral Myocarditis Mimicking Acute Coronary Syndrome: A Transthoracic Doppler Echocardiographic Study

OBJECTIVES

The clinical presentation of myocarditis often mimics acute coronary syndrome. Coronary sinus flow has been used for detection of the presence of myocardial ischemia. Whether myocarditis is associated with changes in coronary sinus flow remains unknown. The aim of this study was to assess coronary sinus flow at the onset and follow-up of myocarditis mimicking acute coronary syndrome using transthoracic Doppler echocardiography (TTE).

METHODS

Sixty-four patients with clinically diagnosed viral myocarditis mimicking acute coronary syndrome underwent TTE on days 3, 7, 30, 90, 180, and 360 after onset. Coronary sinus flow was compared among different points in time.

RESULTS

Compared to healthy participants, all patients with myocarditis had a larger cardiac size, reduced cardiac function, and electrocardiographic and myocardial enzyme abnormalities on days 3 and 7 days (P< .01; P< .05). They later had gradual restoration to normal levels. On days 3 and 7, the coronary sinus flow in patients with myocarditis was extremely lower than that in healthy participants (about one-tenth), although coronary angiography revealed unobstructed arteries. On days 30, 90, 180, and 360, the coronary sinus flow had been increasing; however, it was still far less than that in healthy participants (P < .01).

CONCLUSIONS

Coronary sinus flow depicted by TTE is reduced but recovers with time in viral myocarditis mimicking acute coronary syndrome, which is a useful indicator in the follow-up of this type of myocarditis.

Contemporary perspective on endogenous myocardial regeneration

Considering the complex nature of the adult heart, it is no wonder that innate regenerative processes, while maintaining adequate cardiac function, fall short in myocardial jeopardy. In spite of these enchaining limitations, cardiac rejuvenation occurs as well as restricted regeneration. In this review, the background as well as potential mechanisms of endogenous myocardial regeneration are summarized. We present and analyze the available evidence in three subsequent steps. First, we examine the experimental research data that provide insights into the mechanisms and origins of the replicating cardiac myocytes, including cell populations referred to as cardiac progenitor cells (i.e., c-kit+ cells). Second, we describe the role of clinical settings such as acute or chronic myocardial ischemia, as initiators of pathways of endogenous myocardial regeneration. Third, the hitherto conducted clinical studies that examined different approaches of initiating endogenous myocardial regeneration in failing human hearts are analyzed. In conclusion, we present the evidence in support of the notion that regaining cardiac function beyond cellular replacement of dysfunctional myocardium via initiation of innate regenerative pathways could create a new perspective and a paradigm change in heart failure therapeutics. Reinitiating cardiac morphogenesis by reintroducing developmental pathways in the adult failing heart might provide a feasible way of tissue regeneration. Based on our hypothesis “embryonic recall”, we present first supporting evidence on regenerative impulses in the myocardium, as induced by developmental processes.

Sex-specific assessment of reduced coronary sinus flow in non-hypertensive patients with coronary artery disease at rest

BACKGROUND

Access to data on the coronary flow in the coronary sinus (CS) can aid in the diagnosis of coronary artery disease (CAD). We tested the hypothesis that assessing the CS flow by transthoracic Doppler echocardiography (TTE) at rest can detect coronary artery stenosis in non-hypertensive patients.

METHODS

The antegrade phase of coronary flow in the CS was analyzed and compared in 140 male and 135 female non-hypertensive subjects who had all undergone coronary angiography.

RESULTS

There were statistically significant differences noted between males and females for the CS flow both in normal subjects and patients with CAD. Compared with normal subjects, patients with CAD had significantly lower blood flow in the CS both in males (196.6±174.31 vs. 367.65±168.04 ml/min, P<0.01) and females (183.04±65.46 vs. 244.13±135.43 ml/min P<0.01). For males, the diagnostic sensitivity, specificity, and accuracy of the cutoff value of the CS flow (206 ml/min) for predicting a significant coronary artery stenosis (>70%) were 91.67%, 81.25%, and 85.71%, respectively. For females, those of the cutoff value of the CS flow (195 ml/min) were 85.71%, 75%, and 80%, respectively.

CONCLUSION

TTE can effectively detect coronary hemodynamically significant stenosis in non-hypertensive male and female patients at different cutoff values.