Enhanced myocardial washout and retrograde blood delivery with synchronized retroperfusion during acute myocardial ischemia

Preconditioning with selective autoretroperfusion: In vivo and in silico evidence of washout hypothesis

Introduction

Prompt reperfusion of coronary artery after acute myocardial infarction (AMI) is crucial for minimizing heart injury. The myocardium, however, may experience additional injury due to the flow restoration itself (reperfusion injury, RI). The purpose of this study was to demonstrate that short preconditioning (10 min) with selective autoretroperfusion (SARP) ameliorates RI, based on a washout hypothesis.

Methods

AMI was induced in 23 pigs (3 groups) by occluding the left anterior descending (LAD) artery. In SARP-b (SARP balloon inflated) and SARP-nb (SARP balloon deflated) groups, arterial blood was retroperfused for 10 min via the great cardiac vein before releasing the arterial occlusion. A mathematical model of coronary circulation was used to simulate the SARP process and evaluate the potential washout effect.

Results

SARP restored left ventricular function during LAD occlusion. Ejection fraction in the SARP-b group returned to baseline levels, compared to SARP-nb and control groups. Infarct area was significantly larger in the control group than in the SARP-b and SARP-nb groups. End-systolic wall thickness was preserved in the SARP-b compared to the SARP-nb and control groups. Analyte values (pH, lactate, glucose, and others), measured every 2 min during retroperfusion, suggest a "washout" effect as one important mechanism of action of SARP in reducing infarct size. With SARP, the values progressively approached baseline levels. The mathematical model also confirmed a possible washout effect of tracers.

Discussion

RI can be ameliorated by delaying restoration of arterial flow for a brief period of time while pretreating the infarction with SARP to restore homeostasis via a washout mechanism.

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.

Unstable Angina Pectoris: An Interventional Approach to Management

The therapy of unstable angina has changed consider ably in the last 15 years. An improved understanding of the pathophysiology has led to many of the changes. Thrombus, platelet activation, progression of athero sclerosis, and coronary vasospasm all appear to have a role. Initial management in unstable angina should begin with aggressive medical therapy with nitrates, calcium antagonists, beta blockers, and aspirin. In patients who are refractory to aggressive medical management, early cardiac catheterization and coronary arteriography is in dicated. The literature appears to confirm that patients with unstable angina who are stabilized with aggressive medical therapy fare as well as those treated with emer gency bypass surgery. Percutaneous transluminal coro nary angioplasty (PTCA) is the treatment of choice in medically refractory unstable angina patients with single-vessel coronary disease.

New approaches include culprit lesion angioplasty, thrombolytic therapy, coronary sinus retroperfusion, and new catheter-based revascularization methods such as intracoronary stents, laser methods and atherectomy. Culprit lesion angioplasty involves angioplasty of only the angina-producing artery in patients with multivessel coronary disease. Early data suggest that this may be an effective short-term alternative to multivessel PTCA or bypass surgery. Recent data also suggest a beneficial role for thrombolytic therapy and synchronized coronary si nus retroperfusion with arterial blood in patients with unstable angina. New catheter-based approaches are in the early stages of development, and their eventual role in the treatment of coronary artery disease and unstable angina remains to be elucidated.

Direct Left Ventricle to Great Cardiac Vein Retroperfusion: A Novel Alternative to Myocardial Revascularization

BACKGROUND

As the number of patients with diffuse coronary artery disease continues to grow, there is renewed interest in alternative methods of perfusing the ischemic myocardium. We tested the feasibility of myocardial retroperfusion via a direct left ventricle-to-great cardiac vein (LV-GCV) conduit to support regional contractility in this setting.

METHODS

LV-GCV flow was established using an extracorporeal circuit in 5 dogs. Left ventricle (LV) pressure, aortic pressure, regional myocardial segment length, and circuit blood flow were measured prior to left anterior descending coronary artery (LAD) ligation, following LAD ligation, and after LV-GCV circuit placement. To eliminate backward flow during diastole, an in-line flow regulator was placed. Regional myocardial function was quantified by pressure-segment length loop area divided by end-diastolic segment length (PSLA/EDSL).

RESULTS

LAD ligation reduced PSLA/EDSL from 10.0 +/- 1.2 mm Hg mm to 1.6 +/- 0.3 mm Hg mm (P < .05). With LV-GCV retroperfusion, mean peak systolic flow was +152 +/- 14 mL/min, mean peak diastolic flow was -39 +/- 11 mL/min, and net mean flow was +36 +/- 13 mL/min. Regional function recovered to approximately 39% of baseline (3.9 +/- 0.4 mm Hg mm, P < .05). Upon elimination of backflow, mean flow increased to +41 +/- 12 mL/min and regional function recovered even further to approximately 47% of baseline (4.6 +/- 0.7 mm Hg mm, P < .05).

CONCLUSIONS

A LV-GCV circuit can significantly restore regional function to the acutely ischemic myocardium. An inline valve that eliminates backward diastolic flow improves regional function even further. This approach may provide an effective therapy for diffuse coronary disease not amenable to traditional revascularization strategies.

Angiogenesis in ischemic human myocardium: clinical results after 3 years

BACKGROUND

Using the human fibroblast growth factor we could already demonstrate the induction of neoangiogenesis in the ischemic human myocardium.

METHODS

Forty patients, who were undergoing elective coronary artery bypass grafting were randomly selected and allotted either to a treatment or a control group. In 20 patients (study group) fibroblast growth factor was injected directly into the myocardium, close to the left anterior descending coronary artery. The control group comprised 20 patients who had been injected with heat denatured fibroblast growth factor. The 3-year follow-up consisted of a clinical examination, echocardiography, and selective imaging of the internal mammary artery bypass using angiography.

RESULTS

As with the early results, a dense new capillary network could be demonstrated angiographically in the region where the factor had been injected. Echocardiography showed an increase in the left ventricular ejection fraction in the study group. We also found a more pronounced improvement in the clinical appearance of the patients with fibroblast growth factor.

CONCLUSIONS

Fibroblast growth factor, in addition to operative myocardial revascularization, may be the appropriate treatment for patients with peripheral stenosis or diffuse coronary arteriosclerosis. It is necessary to confirm these results in further studies on a larger group of patients.

Reduction of the infarcted area with the use of simplified coronary sinus retroperfusion during experimental coronary artery occlusion

This study examined if the use of simplified coronary sinus retroperfusion would lead to any reduction in the infarcted area associated with improved right and left ventricular function. Twelve mongrel dogs were entered in this study. Following anesthesia, a fast response thermistor was placed on the pulmonary artery via the jugular vein and aorta via the left ventricular apex. The left anterior descending artery (LAD) was separated from the vein. A retrograde cardioplegia catheter was inserted into the coronary sinus. Following these procedures, LAD was occluded for a period of 3.5 h. After 30 min ischemia, the aorta-coronary sinus connection was established. The animals were divided into two equal groups. One group was not treated and was considered the control group (six animals). In the remaining group (six animals), retroperfusion was used and was considered the retroperfusion group. At the end of the study, the left ventricular ejection fraction was 65+/-15% in the retroperfusion group and 48+/-5% in the control group (P<0.05). The left ventricular stroke work index was 0.44+/-0.04 (g m/kg) in the retroperfusion group and 0.31+/-0.05 (g m/kg) in the control group (P<0.05). Cardiac output was 1650+/-75 ml/min in the retroperfusion group and 1250+/-125 ml/min in the control group. The ratio of the infarct size to the area at risk was 49+/-5% in the control group and 7+/-3% in the retroperfusion group. In light of these studies, we conclude that simplified coronary sinus retroperfusion appears to be an effective method that must be taken into consideration.

LV-powered coronary sinus retroperfusion reduces infarct size in acutely ischemic pigs

BACKGROUND

We developed a prosthetic left ventricle (LV) to coronary sinus (CS) shunt (LVCSS) that is autoregulating and provides LV-powered retrograde perfusion of the coronary sinus.

METHODS

Each of 20 Yorkshire pigs underwent 1 hour of left anterior descending diagonal artery occlusion followed by 3 hours of reperfusion. The controls (n = 5) did not have shunt treatment. The LVCSS group (n = 9) underwent shunt treatment during the ischemic period. The LVCSS with partial coronary sinus occlusion (PCSO) group (LVCSS+PCSO, n = 6) underwent shunt treatment and PCSO during the ischemic period. Vital staining and planimetry techniques were used to determine the area at risk for infarction and the area of necrosis.

RESULTS

The area at risk was not significantly different among groups. The area of necrosis was decreased by 53% in the LVCSS group and by 73% in the LVCSS+PCSO group when compared to controls (p<0.01 among all groups).

CONCLUSIONS

The LVCSS reduces infarct size in pigs after acute coronary artery occlusion. The addition of PCSO to LVCSS further improves myocardial salvage.

Induction of neoangiogenesis in ischemic myocardium by human growth factors: first clinical results of a new treatment of coronary heart disease

BACKGROUND

The present article is a report of our animal experiments and also of the first clinical results of a new treatment for coronary heart disease using the human growth factor FGF-I (basic fibroblast growth factor) to induce neoangiogenesis in the ischemic myocardium.

METHODS AND RESULTS

FGF-I was obtained from strains of Escherichia coli by genetic engineering, then isolated and highly purified. Several series of animal experiments demonstrated the apathogenic action and neoangiogenic potency of this factor. After successful conclusion of the animal experiments, it was used clinically for the first time. FGF-I (0.01 mg/kg body weight) was injected close to the vessels after the completion of internal mammary artery (IMA)/left anterior descending coronary artery (LAD) anastomosis in 20 patients with three-vessel coronary disease. All the patients had additional peripheral stenoses of the LAD or one of its diagonal branches. Twelve weeks later, the IMA bypasses were selectively imaged by intra-arterial digital subtraction angiography and quantitatively evaluated. In all the animal experiments, the development of new vessels in the ischemic myocardium could be demonstrated angiographically. The formation of capillaries could also be demonstrated in humans and was found in all cases around the site of injection. A capillary network sprouting from the proximal part of the coronary artery could be shown to have bypassed the stenoses and rejoined the distal parts of the vessel.

CONCLUSIONS

We believe that the use of FGF-I for myocardial revascularization is in principle a new concept and that it may be particularly suitable for patients with additional peripheral stenoses that cannot be revascularized surgically.

Evaluation of an active coronary perfusion balloon device using Doppler flow wire during PTCA

The aim of this study was to assess whether active coronary perfusion catheters (APC) can provide a sufficient coronary flow in large caliber vessels during balloon inflation. To prevent myocardial ischemia during PTCA, these APC may be employed. However, it is as yet unknown whether the active flow rate of these devices approaches the flow rate prior to PTCA during balloon inflation. Therefore, we measured the efficacy of the APC during balloon inflation in vessels supplying a large amount of myocardium. In 12 patients (1 female, 11 males, 53 +/- 12.6 yr) with stenosed vessels (average diameter 3.4 +/- 0.26 mm), the coronary flow velocity was measured using a 0.014" Doppler guidewire, which was placed distally bypassing the balloon of the APC. The active perfusion balloon catheter was advanced through a 7F guiding catheter along a 0.014" guidewire. After removal of the guidewire, arterial blood being withdrawn from the side port of the femoral angioplasty sheath was pumped through the catheter to the distal coronary vessel. The perfusion volumes of the pump were set to different levels between 30 to 60 ml/min. Intracoronary flow rate was calculated by the angiographically assessed vessel luminal area [symbol: see text] average peak velocity [symbol: see text] 0.5. The mean coronary flow rate prior to PTCA was 43 +/- 17.7 ml/min. Maximum flow during PTCA was 55 +/- 19.6 ml/min. We found a good correlation between the preset external pump rate and the coronary flow in situ (r = 0.92). Pre-PTCA flow rates were achieved in 11 of 12 patients (92%) during balloon inflation. No relevant decrease in the arterial pressure occurred during dilation times of 4.6 +/- 1.63 min. Only two patients showed significant ECG changes during these balloon inflations. After an average follow-up period of 13 +/- 6.3 mo, only one patient (8%) had a significant re-stenosis requiring the implantation of a stent. The combination of intravascular Doppler velocity measurements with quantitative coronary angiography offers the opportunity of exact online flow registration during angioplasty. Using APC, It is possible to maintain a sufficient coronary flow in the distal vessel during balloon inflation even in large vessels. Therefore, as compared with mechanical circulatory assist devices, coronary assist by APC is a little invasive, but according to our measurements it might be a sufficient tool for performing PTCA also in high-risk patients.

Salvage of ischemic myocardium with simplified and even delayed coronary sinus retroperfusion

BACKGROUND

Despite the proven efficacy of pressure-controlled intermittent coronary sinus obstruction (PICSO) and synchronized retrograde perfusion (SRP) in salvaging ischemic myocardium, wide application of these coronary sinus (CS) retroperfusion techniques has been limited by concerns about their safety and complexity and in particular the need for repeated occlusion of the CS with a balloon. To address these concerns a simplified retroperfusion technique (SR) was developed that continuously infuses superior vena caval blood at 7 mL/min into the CS catheter without balloon occlusion.

METHODS

Thirty pigs underwent 90 minutes of ischemia imposed by snaring the two largest diagonal branches of the left anterior descending artery and were randomized to one of five treatment groups: One group received no retroperfusion (control). Three groups had immediate (Im) institution of PICSO, SRP, or SR. In a final group, an initial 60 minutes of ischemia was followed by 30 minutes of delayed SR with superior vena caval blood. All animals were then placed on cardiopulmonary bypass and, after a 60-minute cardioplegic arrest, the coronary artery obstructions were removed, to simulate surgical revascularization. This was followed by 3 hours of reperfusion. The area of myocardium at risk and the area of infarction were determined by methylene blue and triphenyltetrazolium chloride staining with planimetric quantification.

RESULTS

Results are reported as mean +/- standard deviation. The area of the left ventricle at risk for infarction was similar in all the treatment groups and represented 22.3% +/- 4.1% of the left ventricular mass. The area of infarction after 3 hours of reperfusion was 48.5% +/- 11.0% for the control group, 26.8% +/- 7.3% for Im-PICSO, 24.9% +/- 4.8% for Im-SRP, 22.4% +/- 6.6% for Im-SR, and 27.7% +/- 7.2% for delayed SR (p < 0.01 for each group versus control). The mean CS pressure (in mm Hg) during treatment was 6.3 +/- 1.7 for the control group, 25.7 +/- 4.5 for Im-PICSO, 22.8 +/- 3.7 for Im-SRP, 5.0 +/- 1.5 for Im-SR, and 6.3 +/- 2.1 for delayed SR (p < 0.01 for Im-PICSO and Im-SRP versus control).

CONCLUSIONS

The simplified retroperfusion technique is as effective as PICSO and SRP in salvaging ischemic myocardium, but is considerably simpler. The simplified retroperfusion technique is inherently safer because of the lower CS pressures imposed by low flows and the lack of CS balloon obstruction. The efficacy of delayed SR has profound implications on possible mechanisms of ischemic myocardial salvage. Further investigation is warranted.

Combined intraaortic balloon counterpulsation with synchronized coronary venous retroperfusion: the United States experience

Prompted by severe cardiogenic shock, impending or manifest, three cases from the United States Retroperfusion Clinical Trials utilized intraaortic balloon counterpulsation combined with retroperfusion. Temporary stabilization and improvement was noted in all three cases and long-term survival was seen in two of the cases. The clinical and physiologic bases for combined use of these modalities is discussed.

Short-term synchronized retroperfusion before reperfusion reduces infarct size after prolonged ischemia in dogs

BACKGROUND

Previous studies have demonstrated that synchronized coronary venous retroperfusion (SRP) can restore blood flow to the ischemic myocardium, resulting in infarct size reduction and improvement of the left ventricular function. Despite the nutritive blood flow achieved by SRP being relatively limited, SRP has been shown to improve washout of by-products from the ischemic myocardium. The aim of this study was to investigate whether short-term SRP immediately prior to reperfusion would attenuate the deteriorative phenomena following reperfusion.

METHODS AND RESULTS

Closed-chest anesthetized dogs underwent 3 hours of left anterior descending coronary artery (LAD) occlusion. The dogs were then randomized into two groups: (1) control group (n = 9), in which the occlusion was immediately followed by 3-hour reperfusion; or (2) SRP group (n = 9), in which SRP was started 3 hours after occlusion and maintained for 30 minutes with sustained occlusion followed by 2.5-hour reperfusion with simultaneous discontinuation of SRP. There were no statistical differences between the groups in global hemodynamics and degree of ischemia measured by radiolabeled microspheres. Myocardial infarct size (triphenyltetrazolium method) expressed as percentage of risk area was significantly smaller in the SRP group (24 +/- 7%, mean +/- SEM) than in the control group (54 +/- 9%). The extent of myocardial hemorrhage expressed as percentage of infarct size was also significantly reduced in the SRP group (3 +/- 2%) compared with the control group (24 +/- 6%). The increase in end-diastolic wall thickness in the ischemic area after reperfusion assessed by two-dimensional echocardiography was significantly less in the SRP group. Blood flow measurements after reperfusion demonstrated the occurrence of no-reflow phenomenon only in the control group. Histological examination revealed extensive myocardial hemorrhages only in the control group, which extended into the nonnecrotic myocardium in four of nine hearts and extensive contraction band necrosis compared with the SRP group.

CONCLUSIONS

Short-term SRP prior to reperfusion can reduce infarct size, myocardial hemorrhage, wall swelling, and no-reflow phenomenon. The mechanism of this beneficial effect is not clear but might be due to gradual reperfusion and washout of by-products from the ischemic myocardium before fully oxygenated arterial blood reperfusion.

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

OBJECTIVES

This study was designed to determine the efficacy of synchronized coronary sinus retroperfusion of arterial blood in reducing myocardial ischemia associated with the performance of high risk coronary angioplasty.

BACKGROUND

Previous animal and clinical work has demonstrated the efficacy of this technique in supporting ischemic myocardium.

METHODS

Twenty-one patients were randomized to alternately receive coronary sinus retroperfusion support during either the second or the third coronary angioplasty balloon inflation, after an initial unsupported brief control inflation. Myocardial ischemia was assessed by the extent of echocardiographic left ventricular wall motion abnormality, quantified ST segment deviation and hemodynamic and anginal variables during balloon inflations performed with and without coronary sinus retroperfusion support. Regional wall motion score was defined as hyperkinesia (-1), normokinesia (0), hypokinesia (+1), akinesia (+2) and dyskinesia (+3).

RESULTS

A reduction in the echocardiographic left anterior descending regional wall motion score in retroperfusion-supported (1.7 +/- 2.1) versus unsupported (2.7 +/- 1.6) inflations (p < 0.05) was noted. Twelve-lead electrocardiographic monitoring revealed no additional ST segment deviation during supported (173 +/- 95 s) compared with unsupported (129 +/- 87 s) angioplasty inflations despite a significantly longer duration of supported inflations (p < 0.004). Mean and peak systolic coronary sinus pressures differed during supported inflations (21 +/- 6 and 44 +/- 13 mm Hg) versus unsupported inflations (10 +/- 4 and 16 +/- 5 mm Hg) (p < 0.001). There was no difference in hemodynamic or anginal variables.

CONCLUSIONS

A reduction in ischemia as defined by wall motion abnormality during retroperfusion-supported compared with unsupported angioplasty balloon inflations was documented. No additional ST segment deviation occurred during retroperfusion-supported compared with unsupported balloon inflations despite a significantly longer duration of supported inflations. No difference in hemodynamic or anginal variables was noted.

Supported angioplasty with synchronized retroperfusion in high-risk patients with left main trunk or near left main trunk obstruction

To test the feasibility of synchronized retroperfusion (SRP) as a support device of percutaneous transluminal coronary angioplasty (PTCA) for high-risk patients, 10 patients with left main trunk or near left main trunk obstruction underwent PTCA with SRP. An 8.5F retroperfusion catheter was inserted from the antecubital vein into the coronary sinus. Arterial blood was supplied through the catheter into the myocardium with a retroperfusion pump during the diastolic phase by means of ECG triggering. In all patients, the narrowings were successfully dilated and an improvement of more than 20% in the luminal diameter stenosis was achieved; however, narrowing of more than 50% (58%) remained in one patient. In all patients, systemic hemodynamics was maintained for more than 30 seconds during balloon inflation. In seven patients, a 60-second balloon inflation was possible without any collapse of systemic hemodynamics. To test the protective effect of SRP on myocardial ischemia and impairment of systemic hemodynamics, balloon inflation without SRP was performed in eight patients after successful dilatation. The duration for balloon inflation with SRP (71 +/- 30 seconds; n = 8) was significantly longer than that without SRP (56 +/- 30 seconds; n = 8). The decrease in systolic aortic pressure, the increase in pulmonary diastolic pressure, and ST-T segment elevation in the precordial lead of ECG during balloon inflation with SRP were less than those during balloon inflation without SRP. After PTCA, angina was not provoked by exercise stress testing in any of the 10 patients. We concluded that SRP is a beneficial support device of PTCA for high-risk patients.

Short-term treatment with synchronized coronary venous retroperfusion before full reperfusion significantly reduces myocardial infarct size

The efficacy of short-term synchronized coronary venous retroperfusion (SRP) before full arterial reperfusion was studied in a canine model. A control group (n = 6) was subjected to 90 minutes of occlusion of the left anterior descending coronary artery, which was followed by 6 hours of reperfusion. In another group (n = 6) the left anterior descending coronary artery was occluded for 2 hours followed by 5.5 hours of reperfusion. In this group SRP was applied for 30 minutes before full reperfusion. Myocardial regional blood flow was measured with the use of colored microspheres. During occlusion of the left anterior descending coronary artery, there was severe myocardial ischemia in both groups. Blood flow in the subendocardial area was, however, significantly better in the SRP group (0.51 +/- 0.17 ml/min/gm after 3.5 hours of reperfusion) than in the control group (0.29 +/- 0.16 ml/min/gm) after 4 hours of reperfusion (p less than 0.05). Left ventricular function was assessed as global ejection fraction from a left ventriculogram. Ejection fraction was reduced during ischemia in both groups (control = 38% +/- 3%, SRP = 32% +/- 8%). This dysfunction remained after 4 hours of reperfusion. Infarct size was assessed by means of triphenyltetrazolium chloride staining. The myocardial area at risk was similar in the two groups (control = 33.1% +/- 5.3%, SRP = 30.6% +/- 6.5%). Infarct size, which was expressed as the percent of the area at risk, was significantly smaller in the SRP group (17.2% +/- 14.6%) than in the control group (36.0% +/- 8.1%; p = 0.0197).(ABSTRACT TRUNCATED AT 250 WORDS)

Preservation of regional myocardial ultrasonic backscatter and systolic function during brief periods of ischemia by synchronized coronary venous retroperfusion

This study examines the effects of brief periods of ischemia on average and cardiac cycle-dependent variation of regional ultrasonic backscatter paralleled with changes in regional myocardial contraction, and to what extent these changes could be reversed by synchronized coronary venous retroperfusion. In five closed-chest dogs, the left anterior descending coronary artery was occluded on four occasions for a 2-minute period and retroperfusion was applied randomly to two of the coronary occlusions. Complete functional recovery was allowed between the occlusions. Two-dimensional echocardiographic images were obtained before and at the peak of the 2-minute occlusion period. Regional myocardial contraction as measured by fractional area change and systolic wall thickening during untreated occlusions decreased from 33.9 +/- 14.0% to -0.15 +/- 6.2%, and from 22.0 +/- 1.8% to -17.9 +/- 2.2%, whereas during retroperfusion-treated occlusions it changed from 37.4 +/- 8.5% to only 23.4 +/- 11.2% (p less than 0.005 versus baseline), and from 24.1 +/- 2.8% to only 12.7 +/- 2.0% (p less than 0.005 versus baseline), corresponding to a preservation of 62% and 52% of baseline regional contraction, respectively. Average regional gray level (arbitrary units) during untreated coronary occlusions exhibited a significant increase in the ischemic regions, from 5.6 +/- 2.7 at baseline to 11.5 +/- 4.4 during occlusion (p less than 0.005); during retroperfusion-treated occlusions, average gray level increased from 4.7 +/- 3.6 to only 6.3 +/- 3.6 (NS). Untreated coronary artery occlusions resulted in a systolic increase in gray level in the ischemic region, followed by a diastolic decrease.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetic analysis of coronary venous retroinfusion: a comparison with anterograde coronary artery drug administration using metoprolol as a tracer

Plasma and myocardial tissue concentrations of metoprolol were studied in ischemic and nonischemic areas of 22 pigs after 90 (n = 19) and 16 (n = 3) min of left anterior descending coronary artery occlusion. Group A (n = 6) received simultaneous intravenous metoprolol (0.2 mg/kg body weight) and tritium-labeled (3H)-metoprolol (0.2 mg/kg) retrogradely into the coronary vein. In group B (n = 5), metoprolol and 3H-metoprolol were administered in the same way, but at half the volume to study the influence of derived coronary venous pressure on the myocardial concentration of drug. In group C (n = 3), metoprolol was given retrogradely and saline solution was infused into the left anterior descending artery before induced death to wash out metoprolol from the coronary veins. To rule out a possible influence of the development of myocardial necrosis on drug distribution, metoprolol was retroinfused after 1 min of arterial occlusion in three pigs (group D). In group E (n = 5), metoprolol (0.2 mg/kg) was infused anterogradely into the left anterior descending artery. Peak plasma concentration was significantly higher after intravenous infusion of metoprolol (1,188 +/- 503 nmol/liter) than after coronary venous infusion (417 +/- 155 nmol/liter; p less than 0.001). In groups A and B, the nonischemic myocardial concentration of metoprolol was 250 to 300 pmol/g, whether the drug was infused intravenously or into the coronary vein. Coronary venous retroinfusion, however, resulted in a substantial accumulation of metoprolol in the ischemic myocardium. In group A pigs, subendocardial myocardial concentration was 16,800 +/- 7,774, mid-myocardial 39,590 +/- 18,043 and subepicardial 57,143 +/- 29,030 pmol/g (mean +/- SE). The ischemic myocardial concentration in pigs from group B was somewhat less pronounced, probably secondary to a lower coronary venous pressure (15 +/- 3 mm Hg) with the lower volume of infusion (6.1 +/- 0.3 ml) in group B compared with 32 +/- 5 mm Hg with a 14 +/- 1 ml infusion in group A. Coronary artery anterograde administration resulted in myocardial ischemic and nonischemic zone drug concentrations similar to those observed after retroinfusion into the coronary vein. With both modes of administration, there was a transmyocardial gradient from a somewhat lower drug concentration in the subendocardium, toward an increasing level in the mid-myocardium, to the highest concentration in the subepicardial zone of the ischemic myocardium. Coronary venous retroinfusion resulted in pronounced drug accumulation in the ischemic myocardium. The derived coronary venous pressure during infusion influenced the concentration of drug.(ABSTRACT TRUNCATED AT 400 WORDS)

Retrograde coronary venous administration of recombinant tissue-type plasminogen activator: a unique and effective approach to coronary artery thrombolysis

Recent studies of interventional therapy by way of the coronary venous system have demonstrated that it can protect acutely ischemic myocardium. To evaluate the efficacy of coronary venous retroinfusion compared with systemic intravenous administration of recombinant tissue-type plasminogen activator (rt-PA), 14 dogs were studied with a copper coil-induced thrombus in the left anterior descending coronary artery. The rt-PA (24,000 fluorescence units/kg) was administered continuously, either intravenously (n = 8) or retrogradely (n = 6), for 30 min beginning 60 min after coronary occlusion. Thrombolysis was determined by repetitive coronary angiography. All dogs were killed 3 h after termination of rt-PA infusion and infarct size was measured by the triphenyltetrazolium chloride staining technique. Complete thrombolysis occurred in five of the six dogs in the retroinfusion group and four of the eight dogs in the systemic intravenous infusion group. Partial lysis was achieved in two dogs treated by intravenous infusion. Lysis did not occur in one dog treated with retroinfusion and in two dogs treated with intravenous infusion. Time to thrombolysis was 13.4 +/- 2.3 min in the retroinfusion group versus 27.8 +/- 4.8 min in the intravenous group (p less than 0.001). Myocardial functional recovery in the ischemic zone measured by two-dimensional echocardiography 60 min after reperfusion was significant only in the retroinfusion group (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Positron emission tomography demonstrates that coronary sinus retroperfusion can restore regional myocardial perfusion and preserve metabolism

Positron emission tomography was used to image blood flow and metabolic tracers in risk zone myocardium after left anterior descending coronary artery occlusion during synchronized coronary venous retroperfusion. Six control and seven intervention open chest dogs had occlusion of the mid left anterior descending coronary artery. Synchronized retroperfusion commenced 25 min later. Flow tracers (rubidium-82 and nitrogen-13 ammonia) were injected retrogradely. Three hours after coronary occlusion, fluorine-18 (F-18) deoxyglucose uptake in the control and treatment groups was compared. At 200 min of occlusion, infarct size was assessed. Retrograde flow tracer uptake was observed in the risk zone in the seven intervention dogs. Fluorine-18 deoxyglucose uptake in the risk zone was increased in five of the six intervention dogs but was reduced in five of the six control dogs. The risk zone to normal zone F-18 deoxyglucose count ratio was higher in the intervention than the control group (1.13 +/- 0.39 vs. 0.59 +/- 0.51; p less than 0.05). The endocardial subsegment risk zone to normal zone F-18 deoxyglucose count ratio was also significantly higher in the intervention group. Percent infarction in the risk zone was 70% lower in the group treated with synchronized retroperfusion than in the control group (18.4 +/- 22.6% vs. 61.2 +/- 25.4%; p less than 0.02). Thus, positron emission tomography revealed that retroperfusion could deliver oxygenated blood and maintain metabolism in risk zone myocardium. Infarct size was limited to 30% of that of control. In acute closure of the left anterior descending coronary artery, synchronized retroperfusion might be considered for maintaining viability of the jeopardized myocardium if the artery cannot be reopened rapidly.

Percutaneous cooling of ischemic myocardium by hypothermic retroperfusion of autologous arterial blood: effects on regional myocardial temperature distribution and infarct size

The effects of synchronized coronary venous retroperfusion of cooled autologous arterial blood on regional myocardial temperature distribution and infarct size were studied in open chest dogs with 3.5 h of left anterior descending coronary artery occlusion. After 30 min of occlusion, the dogs were randomly assigned to one of three groups: 1) untreated control group (n = 5), 2) normothermic retroperfusion group (infusion temperature 32 degrees C) (n = 7), and 3) hypothermic retroperfusion group (infusion temperature 15 degrees C) (n = 7). Regional myocardial temperatures were measured by using needle-tipped thermistors stabbed in the 1) anterior wall distal to the occlusion site, 2) anterior wall proximal to the occlusion site, 3) left lateral wall, 4) posterior wall, and 5) right ventricular free wall. Rectal and pulmonary artery temperatures were also measured. In the hypothermic retroperfusion group, the anterior wall temperature decreased rapidly by 5 degrees C at 15 min of retroperfusion (p less than 0.05 vs. normothermic retroperfusion or untreated control groups), whereas the temperature at other sites decreased with a linear trend over time. Myocardial temperatures in the ischemic area (distal anterior wall) were generally lower than those in the other sites during the first 60 min of hypothermic retroperfusion and the largest intramyocardial temperature difference (3.6 degrees C) was found at 15 min after retroperfusion. Infarct size expressed as a percent of the risk area was significantly smaller in the hypothermic retroperfusion group (6.2 +/- 3.3%) than in the control (64.9 +/- 14%) or normothermic retroperfusion groups (24.1 +/- 6.7%).(ABSTRACT TRUNCATED AT 250 WORDS)

Synchronized coronary venous retroperfusion for support and salvage of ischemic myocardium during elective and failed angioplasty

To determine the safety and efficacy of synchronized coronary venous retroperfusion during brief periods of ischemia, 30 patients undergoing angioplasty of the left anterior descending coronary artery were studied. Each patient underwent a minimum of two angioplasty balloon inflations. Alternate dilations were supported with retroperfusion; the unsupported inflations served as the control inflations. Synchronized retroperfusion was performed by pumping autologous femoral artery blood by means of an electrocardiogram-triggered retroperfusion pump into the great cardiac vein through a triple lumen 8.5F balloon-tipped retroperfusion catheter inserted percutaneously from the right internal jugular vein. Clinical symptoms, hemodynamics and two-dimensional echocardiographic wall motion abnormalities were analyzed. Retroperfusion was associated with a lower angina severity score (0.8 +/- 1 vs. 1.2 +/- 1) and delay in onset of angina (53 +/- 31 vs. 37 +/- 14 s; p less than 0.05) compared with the control inflations. The magnitude of ST segment change was 0.11 +/- 0.14 mV with retroperfusion and 0.16 +/- 0.17 mV without treatment (p less than 0.05). The severity of left ventricular wall motion abnormality was also significantly (p less than 0.01) reduced with retroperfusion compared with control (0.7 +/- 1.4 [hypokinesia] vs. -0.3 +/- 1.6 [dyskinesia]). There were no significant changes in hemodynamics, except in mean coronary venous pressure, which increased from 8 +/- 3 mm Hg at baseline to 13 +/- 6 mm Hg with retroperfusion. Four patients required prolonged retroperfusion for treatment of angioplasty-induced complications. The mean retroperfusion duration in these patients was 4 +/- 2 h (range 2 to 7). In the three patients who underwent emergency bypass surgery, the coronary sinus was directly visualized during surgery and found to be without significant injury. There were no major complications. Minor adverse effects were transient atrial fibrillation (n = 2), jugular venous catheter insertion site hematomas (n = 4) and atrial wall staining (n = 1), all of which subsided spontaneously. Thus, retroperfusion significantly reduced and delayed the onset of coronary angioplasty-induced myocardial ischemia and provided effective supportive therapy for failed and complicated angioplasty.

Reversal of chronic regional myocardial dysfunction (hibernating myocardium) by synchronized diastolic coronary venous retroperfusion during coronary angioplasty

A 62 year old man with previous myocardial infarction, an occluded right coronary artery and a 90% stenosis of the left anterior descending coronary artery underwent angioplasty with the support of coronary venous retroperfusion of arterial blood during the procedure. In two of four angioplasty balloon dilations of the left anterior descending coronary artery, synchronized diastolic retroperfusion of the coronary veins with arterial blood was applied to protect the severely dysfunctioning myocardium from additional ischemia. Two-dimensional echocardiography was used to monitor and quantitate alterations in left ventricular function. Retroperfusion of arterial blood resulted in immediate improvement in ischemic zone wall motion despite the totally occluded artery during balloon dilation. Echocardiographic images recorded after angioplasty showed a marked improvement in contraction of the previously dyskinetic segments, with changes similar to those seen during balloon dilations with synchronized diastolic coronary venous retroperfusion. Thus, in this patient, viability of chronically dysfunctioning myocardium could be demonstrated by the improvement in regional wall motion during retroperfusion. This technique could eventually be of value to elucidate the anatomic location of viable myocardium while maintaining adequate left ventricular systolic function during coronary artery interventions in the catheterization laboratory.

Amelioration of ischemia during angioplasty of the left anterior descending coronary artery with an autoperfusion catheter

A new autoperfusion balloon angioplasty catheter with sideholes proximal and distal to the balloon--facilitating distal blood flow during inflation--was compared with standard angioplasty catheters in a prospective, randomized study with blinded data analysis. Hemodynamic and electrocardiographic markers of ischemia after 1 minute of standard or autoperfusion catheter inflations were compared with ischemia after control inflation with standard balloons. In the patient group randomized to standard balloon inflation only, ST-segment elevation after control inflation with a standard balloon catheter was 0.37 +/- 0.04 mV; ST-segment elevation after final balloon inflation with a standard catheter was unchanged at 0.35 +/- 0.04 mV (difference not significant). In the group randomized to the autoperfusion catheter, control inflation with a standard catheter resulted in 0.48 +/- 0.1 mV ST elevation; final inflation with the autoperfusion catheter demonstrated 0.16 +/- 0.09 mV ST elevation (p less than 0.005). Autoperfusion catheter inflation was continued for 2 minutes without change in electrocardiographic findings: ST segments remained at 0.08 +/- 0.03 mV, unchanged from 0.07 +/- 0.03 mV before angioplasty (difference not significant). Thus, while coronary angioplasty performed with standard catheters resulted in marked ST-segment elevation, in patients undergoing angioplasty with the autoperfusion catheter, ischemia was generally not seen, despite sustained balloon inflation for 2 minutes.

Haemodynamic observations during percutaneous transluminal coronary angioplasty in the presence of synchronised diastolic coronary sinus retroperfusion

Animal studies have demonstrated that synchronised coronary sinus retroperfusion with arterial blood can provide effective perfusion of ischaemic myocardium. Preliminary clinical studies have shown that the technique can also be used with safety in human beings, and in the present study its effectiveness was assessed in three patients undergoing repeated coronary artery occlusions during percutaneous transluminal coronary angioplasty. Arterial blood was removed via an 8F catheter positioned in the femoral artery and delivered by a retroperfusion pumping system to a 7F retroperfusion balloon catheter positioned in the anterior cardiac vein. Ischaemia-related indices were monitored both before and during coronary sinus retroperfusion. These indices included high fidelity left ventricular pressure recordings and pressure derived indices (including velocities of isovolumic contraction and relaxation), as well as electrocardiographic changes and symptoms. Analysis of these variables showed that the ischaemic changes induced during coronary artery occlusion were not prevented by this type of coronary sinus retroperfusion. There was no major complication in any of the patients. It may be that adaptation of the technique or the use of alternative end points will establish a benefit, but further modifications of the delivery system are necessary for effective clinical use.

Coronary sinus interventions: from concept to clinics

For almost 100 years the coronary venous system has attracted researchers as an access route to deprived myocardium. Different concepts have been tried and numerous experimental studies have been performed to evaluate whether coronary sinus occlusion, retroinfusion, and retroperfusion of arterial blood via the coronary sinus represent an effective treatment of myocardial ischemia. The early successful studies of Drs. Gregg, Eckstein, Beck and others led to the application of the Beck II procedure, a permanent retroperfusion technique used in the early 1950s to revascularize patients with diffuse atherosclerosis. The coronary sinus route was also used to retroperfuse blood intraoperatively during opening of the heart to keep the heart beating. Excessive mortality and severe side effects, such as myocardial edema and hemorrhage, and an insufficiently advanced technology resulted in the temporary demise of the coronary sinus approaches. Recently, however, the need to improve myocardial protection, despite enormous advances in coronary bypass surgery and interventional cardiology, has resulted in renewed interest in the coronary sinus as an access route to deprived myocardium. Advances in technology such as percutaneous catheter techniques have improved access to the coronary venous system and allowed for a physiological adaptation of coronary sinus retroperfusion techniques. Today the three major coronary sinus techniques, i.e., sychronized retroperfusion (SRP), retroinfusion of cardioplegia during cardiac arrest and retroinfusion of pharmaceutical agents in the normal working heart, and pressure-controlled intermittent coronary sinus occlusion (PICSO) have been documented as providing superior protection of jeopardized myocardium in selected subsets of patients. All of these techniques currently are under clinical consideration; the retroinfusion of cardioplegia has already found wide clinical acceptance, SRP and PICSO have only recently been tested in first clinical trials. Due to a vast resurgence in interest, it is desirable to survey the results obtained with each of these techniques, to discuss the pathophysiology and mode of action of coronary sinus interventions, and to assign them a place in the perspective of conventional therapies. Furthermore, an attempt will be made to weigh individual coronary sinus techniques against each other, discuss in which clinical settings each of them may be most effective, and define issues facing current development.