Clinical applications of coronary sinus retroperfusion during high risk percutaneous transluminal coronary angioplasty

A novel therapy in microvascular obstruction in ST-elevation myocardial infarction: pressure-controlled intermittent coronary sinus occlusion therapy

Percutaneous coronary intervention has transformed the management of ST-elevation myocardial infarction (STEMI) due to a reduction in early mortality and need for repeat revascularization. However, the conventional revascularization strategy, combined with state-of-the-art anti-thrombotic and antiplatelet therapies, can still be associated with poor clinical outcome in some patients, because of reperfusion injury and microvascular obstruction contributing to the infarct size. To address this important therapeutic need, a broad-range of device-based treatments have been introduced. This is an overview of the pressure-controlled intermittent coronary sinus occlusion (PiCSO) device (Miracor Medical SA) which has been proposed for STEMI patients. PiCSO therapy could lead to an improved perfusion, decrease microvascular dysfunction, and thus potentially reduce infarct size.

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.

Endometrial regenerative cells for treatment of heart failure: a new stem cell enters the clinic

Heart failure is one of the key causes of morbidity and mortality world-wide. The recent findings that regeneration is possible in the heart have made stem cell therapeutics the Holy Grail of modern cardiovascular medicine. The success of cardiac regenerative therapies hinges on the combination of an effective allogeneic “off the shelf” cell product with a practical delivery system. In 2007 Medistem discovered the Endometrial Regenerative Cell (ERC), a new mesenchymal-like stem cell. Medistem and subsequently independent groups have demonstrated that ERC are superior to bone marrow mesenchymal stem cells (MSC), the most widely used stem cell source in development. ERC possess robust expansion capability (one donor can generate 20,000 patients doses), key growth factor production and high levels of angiogenic activity. ERC have been published in the peer reviewed literature to be significantly more effect at treating animal models of heart failure (Hida et al. Stem Cells 2008).

Current methods of delivering stem cells into the heart suffer several limitations in addition to poor delivery efficiency. Surgical methods are highly invasive, and the classical catheter based techniques are limited by need for sophisticated cardiac mapping systems and risk of myocardial perforation. Medistem together with Dr. Amit Patel Director of Clinical Regenerative Medicine at University of Utah have developed a novel minimally invasive delivery method that has been demonstrated safe and effective for delivery of stem cells (Tuma et al. J Transl Med 2012). Medistem is evaluating the combination of ERC, together with our retrograde delivery procedure in a 60 heart failure patient, double blind, placebo controlled phase II trial. To date 17 patients have been dosed and preliminary analysis by the Data Safety Monitoring Board has allowed for trial continuation.

The combined use of a novel “off the shelf” cell together with a minimally invasive 30 minute delivery method provides a potentially paradigm-shifting approach to cardiac regenerative therapy.

Myocardial protection via the coronary sinus

BACKGROUND

Recent reports on facilitated reperfusion therapy re-address interests in coronary sinus interventions (CSI). Patients in whom short time results have been reported earlier were re-evaluated, with the aim of gathering the long-term results of pressure-controlled intermittent coronary sinus occlusion (PICSO) generated in patients with acute myocardial infarction (MI) and revascularization.

METHODS AND RESULTS

Thirty-four patients with ST elevated MI, in whom complete revascularization was achieved, underwent primary thrombolysis with or without PICSO. Follow-up data from these patients were collected for at least 48 months. Immediate perioperative differences were observed for time to peak creatine kinase (CK), as well as cumulative CK. In addition, the time until reperfusion was considerably less than for the control group (p=0.014). Long-term data showed significant differences in reinfarction (p=0.015), as well as in major adverse cardiovascular events, between the 2 groups (p<0.0001).

CONCLUSION

These data, because of the wide interval between collection and current analysis, could have inherited historical bias. Nonetheless, they are also uniquely indicating the potential of CSI to induce not only immediate, but also clinically significant long-term, effects as an adjunct to reperfusion therapy. Therefore, CSI should be, once again, on the study agenda and be placed under contemporary and best-available scientific scrutiny.

Coronary Sinus Reducer Stent for the Treatment of Chronic Refractory Angina Pectoris

OBJECTIVES

This study sought to evaluate the safety of the Coronary Sinus Reducer (Neovasc Medical, Inc., Or Yehuda, Israel) as a potential alternate therapy for patients with refractory angina who are not candidates for conventional revascularization procedures.

BACKGROUND

Increased coronary sinus (CS) pressure can reduce myocardial ischemia by redistribution of blood from nonischemic to ischemic territories. The Coronary Sinus Reducer is a percutaneous implantable device designed to establish CS narrowing and to elevate CS pressure. In preclinical experiments, implantation of the Reducer was safe and was associated with improved ischemic parameters. In the present study, the safety and feasibility of the Coronary Sinus Reducer was evaluated in patients with refractory angina who were not candidates for revascularization.

METHODS

Fifteen coronary artery disease patients with severe angina and reversible ischemia were electively treated with the Reducer. Clinical evaluation, dobutamine echocardiography, thallium single-photon emission computed tomography, and administration of an angina questionnaire were performed before and 6 months after implantation. Cardiac computed tomography was performed 2 days and 6 months after implantation.

RESULTS

All procedures were completed successfully. No procedure-related adverse events occurred during the periprocedural and the follow-up periods. Angina score improved in 12 of 14 patients. Average Canadian Cardiovascular Society score was 3.07 at baseline and 1.64 at follow-up (n = 14, p < 0.0001). Stress-induced ST-segment depression was reduced in 6 of 9 patients and was eliminated in 2 of these 6 (p = 0.047). The extent and severity of myocardial ischemia by dobutamine echocardiography and by thallium single-photon emission computed tomography was reduced (p = 0.004 [n = 13] and p = 0.042 [n = 10], respectively).

CONCLUSIONS

Implantation of the Coronary Sinus Reducer is feasible and safe. These findings, along with the clinical improvement observed, support further evaluation of the Reducer as an alternative treatment for patients with chronic refractory angina who are not candidates for coronary revascularization.

Magnesium-enriched coronary sinus retroperfusion during acute coronary artery occlusion

BACKGROUND

The protective effect of coronary sinus retroperfusion in cases of ischaemic myocardium is clearly known. It restores the blood flow to the ischaemic tissue, reduces the infarct size, and improves the left ventricular pump function.

METHODS

In this study, we investigated the effects of coronary sinus retroperfusion with the addition of magnesium sulphate on myocardial haemodynamics. A total of sixteen animals were entered into the study and divided equally into four groups: group I, control group, left anterior descending (LAD) coronary artery occlusion only; group II, LAD artery occlusion and Mg SO infusion; group III, LAD occlusion and retrograde coronary sinus perfusion; and group IV, LAD occlusion, retrograde coronary sinus perfusion and Mg SO infusion.(4) (4)

RESULTS

Haemodynamic measurements were obtained throughout the study, at baseline, during the first and third hour of occlusion, and in the second, fourth and sixth hour of reperfusion. Although, the cardiac index was decreased in all groups, in the second hour of reperfusion it was significantly higher in groups III and IV compared to the control group. In the second hour of reperfusion cardiac index values were 56 +/- 5 and 63 +/- 6 ml/kg per min in groups III and IV respectively (P < 0.05) and as time passed this incremental change in groups III and IV became more apparent. In the fourth hour of reperfusion, group II showed significantly higher values than the control group. Group IV had higher values compared to group III at the fourth and sixth hours post-reperfusion. In general there were significant differences between groups II, III and IV at four and six hours post-reperfusion. The first derivative of pressure measured over time-the dP/dt value-was higher in groups III and IV compared to the control group in the first hour of occlusion (being 1650 +/- 55 and 1700 +/- 35 in groups III and IV respectively, and 1420 +/- 45 in the control group) and these differences continued throughout the occlusion and the reperfusion periods (P < 0.05). Group IV had the highest left ventricular stroke work index (LVSWI) values compared to the other groups in various pulmonary capillary wedge pressure (PCWP) measurements (P < 0.05). It was 0.78 g.m/kg at the 20 mmHg PCWP.

CONCLUSIONS

Magnesium, if administered in an antegrade direction had only a limited effect, whereas magnesium-enriched retrograde coronary sinus perfusions appeared to significantly protect the ischaemic myocardium against the hazardous effects of ischaemic reperfusion injury.

Coronary sinus occlusion enhances coronary collateral flow and reduces subendocardial ischemia

On the hypothesis that coronary sinus occlusion (CSO) may reduce myocardial ischemia, we examined the effects of CSO on coronary collateral blood flow and on the distribution of regional myocardial blood flow (RMBF) in dogs. Thirty-eight anesthetized dogs underwent occlusion of the left anterior descending coronary artery with or without CSO and intact vasomotor tone. We measured RMBF and intramyocardial pressure (IMP) in the subendocardium (Endo) and subepicardium (Epi) separately. With intact vasomotor tone, CSO during ischemia significantly increased RMBF in the ischemic region (IR), particularly in Endo from 0.17 +/- 0.03 to 0.33 +/- 0.05 ml x min(-1) x g(-1) (P < 0.05), and increased the Endo/Epi from 0.59 +/- 0.10 to 1.15 +/- 0.15 (P < 0.01). These effects of CSO were partially abolished by adenosine. However, the Endo/Epi was still increased from 0.90 +/- 0.13 to 2.09 +/- 0.30 (P < 0.01). The changes in RMBF in IR were significantly correlated with the peak CS pressure during CSO. The Endo/Epi of IMP in IR was significantly decreased during CSO. In conclusion, CSO potentially enhances coronary collateral flow, and preserves the ischemic myocardium, especially in Endo.

Strategies for the palliation of severe unprotected left main coronary artery disease: use of newer technologies

Angioplasty of unprotected left main coronary artery lesions is associated with high procedural and late mortalities. We describe the successful use of rotational coronary atherectomy with prophylactic supportive measures in the management of a heavily calcified unprotected left main lesion. This report demonstrates that high-risk lesions, previously regarded as unapproachable, may be safety treated with newer technologies.

Perfusion therapy to reduce myocardial ischemia en route to emergency coronary artery bypass grafting for failed percutaneous transluminal coronary angioplasty

Despite improvements in operator technique, catheter technology, and the development of new devices, emergency coronary artery bypass grafting (CABG) is still required in 1%-4% of attempted catheter based revascularization procedures. Patients who require such emergency CABG after failed percutaneous transluminal coronary angioplasty (PTCA) have worse acute outcomes than those undergoing elective CABG, with a higher incidence of Q wave myocardial infarction (MI) and a higher operative mortality. In patients with otherwise refractory abrupt closure, maintenance of antegrade coronary blood flow using perfusion catheters lessens the incidence of Q wave MI and lowers peak creatinine phosphokinase. Direct maintenance of coronary flow thus appears to provide more definitive control of myocardial ischemia than purely adjunctive measures, such as intra-aortic balloon pumping, cardiopulmonary support, or coronary sinus retroperfusion. Although the recent introduction of coronary stents holds great promise for definitive percutaneous reversal of abrupt closure and a dramatic decrease in the incidence of emergency CABG for failed PTCA, maintenance of antegrade flow via perfusion technology remains the cornerstone of management in reducing the perioperative mortality and morbidity of patients who still require emergency bypass surgery after failed PTCA.

Emergency use of cardiopulmonary bypass

Emergency cardiopulmonary support has been used in the United States since 1986. Physicians at participating centers for the National Registry of Elective Supported Angioplasty have contributed data on emergent cardiopulmonary support from their institutions. Results were analyzed to assess the benefits of cardiopulmonary support in patients with hemodynamic collapse. Patients with either cardiac arrest or hemodynamic collapse with cardiogenic shock unresponsive to pressor agents were placed emergently on cardiopulmonary support. Subsequent treatment comprised either angioplasty or surgical revascularization. Patients placed on cardiopulmonary support in < 20 minutes experienced a 41% survival rate across the entire registry of the participating centers of the National Cardiopulmonary Bypass Registry. Two centers with considerable experience demonstrated a 69% survival rate. Patients treated with emergency cardiopulmonary support because of hemodynamic collapse showed improved survival over any other hemodynamic support system. Results have improved for survival with increased operator experience, particularly in the early application group.

Regional flow adjusted hemoperfusion during coronary angioplasty: circulatory support/myocardial protection

Routine percutaneous transluminal coronary angioplasty catheters are adequate and demonstrate high success rates in balloon angioplasty with stable patients. Active hemoperfusion seems to offer an advantage in patients with hemodynamic instability. Active hemoperfusion provides myocardial protection during coronary interventions and can be applied in conjunction with routine angioplasty equipment. When compared with other devices demonstrating clinical utility in a supported angioplasty setting, this flow adjustable active antegrade hemoperfusion pump appears reliable, simple to use, cost-effective, and requires much less instrumentation than the more bulky CPS systems.

Basic view on the pathobiology of myocardial ischemia during coronary angioplasty: implications for cardiac protection

PTCA is not only an effective therapeutic tool but a unique opportunity to study the pathobiology of the human myocardium during ischemia and reperfusion. In addition, it is a good model to assess potential therapeutic interventions. Studies performed during PTCA contributed significantly to the understanding of the metabolic, electrophysiologic, hemodynamic, and coronary perfusion changes in the human heart following coronary occlusion. Combining the data from experimental models and human patients may lead to better techniques for myocardial protection during PTCA and consequently reduce the risk of patients undergoing mechanical revascularization.

Differential effects of synchronized coronary sinus retroperfusion on regional myocardial function during brief occlusion of the left anterior descending and circumflex coronary arteries

To test the hypothesis that coronary sinus retroperfusion would preserve regional myocardial function during either left anterior descending or circumflex occlusion, sonomicrometer crystals were implanted in the midmyocardium of five chronically instrumented dogs. Regional fractional shortening was measured during 5 min of coronary occlusion with and without retroperfusion. Percent fractional shortening in the left anterior descending region fell from 18% at baseline to -4%(dyskinesis) after 3 min of left anterior descending occlusion. With coronary sinus retroperfusion, the percent fractional shortening declined from 16% at baseline to 0 (akinesis) during occlusion. A modest but significant improvement in percent fractional shortening in the ischemic region during left anterior descending occlusion occurred with retroperfusion (p < .05). By contrast, no amelioration of ischemic dysfunction occurred with retroperfusion during circumflex occlusion. Coaxial flow into the great cardiac vein during retroperfusion may provide preferential protection to ischemic myocardium supplied by the left anterior descending coronary artery. However, it is unlikely that the modest degree of improvement in regional function observed during acute left anterior descending occlusion would be mechanically important in the presence of significant ischemic dysfunction.