Coronary sinus interventions during cardiac surgery

Selective autoretroperfusion preserves myocardial function during coronary artery ligation in swine

BACKGROUND

External pumps have been previously used to minimize edema and hemorrhage caused by coronary retroperfusion. The objective of this study was to use a pump-less approach (selective autoretroperfusion, SARP) to preserve myocardial function after acute coronary artery ligation.

METHODS

In five experimental pigs, the LAD artery was ligated distal to the first diagonal and retroperfusion was instituted for three hours from a brachiocephalic artery at 50 mmHg pressure through an adjustable occluder on the cannula. In eight control pigs, the LAD artery was ligated distal to the second diagonal for the same duration with no SARP.

RESULTS

ECG showed more prominent S-T segment elevation in the untreated control group despite the more distal ligation. The degree of myocardial contraction was significantly attenuated in the control group but was largely preserved in the SARP treated group. The myocytes were well preserved in the SARP group with no rupture of venous microvessels. Myocyte edema and disruption was observed in the control group with only mild extracellular edema in the SARP treated group.

CONCLUSION

SARP preserved myocardial function with no damage to the myocyte and venules during three hours of acute LAD ligation.

Coronary venous retroperfusion: an old concept, a new approach

The potential of the coronary veins for revascularization has been evaluated by many investigators for more than a century. The major hurdle has been the damage of veins during sudden exposure to arterial pressure. The solution to this problem has typically involved the use of intricate and complicated apparatus and devices, which has prevented routine clinical utility in the catheterization laboratory. This review examines this old concept from a new perspective and proposes a novel hypothesis to address previous shortcomings. We speculate on an approach that may serve to eliminate the edema and hemorrhage that result during venous retroperfusion as the pressure is suddenly increased to arterial values. We propose the rationale to increase the venous pressure to arterial values more gradually to allow prearterializations of the veins before full exposure of arterial pressure. Finally, we discuss various possible indications for this selective autoretroperfusion strategy to combat myocardial ischemia in cardiogenic shock patients, ST-elevation myocardial infarct patients, no-option patients, and beyond.

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.

Percutaneous transmyocardial intracardiac retroperfusion shunts: technical feasibility in a canine model

PURPOSE

To test the technical feasibility of creating a left ventricle to coronary sinus shunt using endovascular techniques.

MATERIALS AND METHODS

By means of a right jugular vein approach, a needle puncture was made from the coronary sinus to the left ventricle in 10 dogs. The tracts were balloon dilated and lined with 6-mm Wallstents. Shunt patencies, immediate and 4-hours later, were fluoroscopically assessed by contrast material injection into the left ventricle. Blood pressure, pulse, oxygen saturation, and cardiac rhythm were monitored. The dogs were then euthanized. Thoracic cavities and hearts were dissected and inspected.

RESULTS

Technical success and immediate shunt patency were 100%. No cardiac dysrhythmias, electrocardiographic changes, or reduction in voltage potential were seen. Eight (80%) of the shunts were patent at 4 hours, one (10%) had thrombosed, and one dog died. Nine (90%) dogs had no pericardial hematoma and one (10%) had minimal pericardial blood from needle passes into the pericardial sac. The coronary sinuses were intact and no injuries to the valve leaflets or chordae tendineae were seen. The puncture sites were from the coronary sinus, 1-2 mm (mean, 1.3) from its auricular orifice, into the left ventricle, just below the inferior margin of the posterior leaflet of the mitral valve. One dog died at 3 hours with no preceding electrocardiographic evidence of impending demise. Autopsy showed no pericardial hematoma and the heart findings were no different from the other nine dogs.

CONCLUSIONS

Creation of a left ventricle to coronary sinus shunt with use of endovascular techniques is technically feasible. Study of a transmyocardial intracardiac coronary retroperfusion shunt to deliver oxygenated blood to the ischemic myocardium is warranted.

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.

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.

Unusual pitfall of use of retrograde cardioplegia

The use of retrograde cardioplegia can lead to several complications, mainly related to injuries during the cannulation of the coronary sinus. We herein present a case report of injury to the right coronary artery related to kinking due to the pursestring on the right atrium.

Contrast echocardiography and myocardial perfusion

New clinical applications for myocardial contrast echocardiography (MCE) are being developed in both the operating room and the catheterization laboratory. Studies have shown that red blood cell transit time through the myocardium is a measure of myocardial blood flow. Sonicated albumin microbubbles can mimic intramyocardial behavior of red blood cells. Other studies have used MCE to assess collateral flow to determine myocardial viability after acute myocardial infarction. The authors have developed a computer system that allows on-line quantitation of contrast echocardiographic data in the operating room, and this system is able to confirm that bypass grafts are properly placed. The ability to quantitate myocardial flow with MCE may be useful in guiding the sequence of graft placement and for assessing the success of the operation. These measures will help lower the incidence of perioperative infarction. Experiments in our laboratory using the canine model have shown that MCE may be useful in assessing the intramyocardial distribution of retrogradely delivered cardioplegia. This technique may, therefore, assist the surgeon in determining the adequacy of retrograde cardioplegia delivery and may improve myocardial preservation during bypass surgery.

Cardioplegia by way of the coronary sinus for valvular and coronary surgery

Retrograde coronary sinus perfusion has recently reemerged as an attractive means of delivering cardioplegic solutions during open heart procedures. In patients undergoing aortic valve or aortic root surgery, there is no evidence that coronary sinus cardioplegia results in a better myocardial protection than that achieved with the use of standard methods of anterograde cardioplegia delivery. However, the retrograde approach provides distinct technical advantages that might favor its use as an alternative to direct coronary ostial cannulation. In select subgroups of patients undergoing coronary bypass procedures, there is a growing body of evidence that the coronary sinus route may be more effective than the anterograde route because of its superior capacity to ensure homogeneous distribution of cooling and cardioplegia in myocardial areas supplied occluded arteries. The well established safety of coronary sinus cardioplegia in the clinical setting further justifies its inclusion among techniques for ensuring adequate myocardial preservation during surgically induced ischemic arrest.

Coronary venous retroperfusion support during high risk angioplasty in patients with unstable angina: preliminary experience

Synchronized coronary venous retroperfusion was used during coronary balloon angioplasty to support the ischemic myocardium of 20 patients with unstable angina and anatomy at high risk of a coronary event. Hemodynamics and left ventricular function were the major end points of the study. Coronary venous catheterization and retroperfusion were successfully performed in 15 patients. The target vessel was an unprotected left main artery in 2, left anterior descending artery in 10, left circumflex coronary artery in 1 and right coronary artery in 2 patients. A nonsupported balloon inflation (mean 44 +/- 13 s) was compared with a later retroperfusion-supported inflation (mean 145 +/- 21 s). Right anterior oblique left ventriculograms, aortic blood pressure, pulmonary artery pressure and thermodilution cardiac output were obtained before and during peak untreated and treated balloon inflations and on completion of angioplasty. All patients had either a baseline left ventricular ejection fraction less than 0.40 or greater than 40% of contracting myocardium estimated to be at risk for severe ischemia during angioplasty. The cardiac (liters/min per m2) and stroke work (g.m/m2) indexes decreased from mean baseline values of 2.5 +/- 0.52 and 52 +/- 15 to 1.7 +/- 0.47 and 27 +/- 12 (mean +/- SD), respectively, during nonsupported balloon inflations but decreased only to 2.1 +/- 0.52 (p less than 0.01 vs. nonsupported) and to 36 +/- 14 (p = 0.01 vs. nonsupported), respectively, during retroperfusion-supported inflations. Ejection fraction (n = 8) decreased from a baseline value of 55 +/- 13% to 27 +/- 7.3% during nonsupported inflations but only to 39 +/- 10% during retroperfusion-supported inflations (p = 0.01 vs. nonsupported). Regional wall motion (area change) in the ischemic (target) region was reduced from a baseline value of 49 +/- 17% to 11 +/- 16% during nonsupported inflations but only to 27 +/- 15% during retroperfusion-supported inflations (p less than 0.01 vs. nonsupported). All but two patients had a favorable hemodynamic response to retroperfusion. There were no serious adverse effects related to the procedures and no hospital deaths. It is concluded from this preliminary study that coronary venous retroperfusion appears to be safe, to provide hemodynamic support and to improve left ventricular function during angioplasty in patients with unstable angina and anatomy at high risk of a coronary event.

Superiority of retrograde cardioplegia after acute coronary occlusion

Because antegrade cardioplegia may limit the distribution of cardioplegia beyond a coronary occlusion, this study was undertaken to determine whether retrograde coronary sinus cardioplegia provides superior myocardial protection during revascularization of an acute coronary occlusion. In 20 adult pigs, the second and third diagonal branches were occluded with a snare for 1 1/2 hours. Animals were then placed on cardiopulmonary bypass and underwent 30 minutes of ischemic arrest with multidose, potassium, crystalloid cardioplegia. In 10 animals, the cardioplegia was given antegrade through the aortic root, whereas in 10 others, it was given retrograde through the coronary sinus. After the arrest period, the coronary snares were released and all hearts were reperfused for 3 hours. Postischemic damage in the myocardium beyond the occlusions was assessed by wall motion scores using two-dimensional echocardiography (4 = normal to -1 = dyskinesia), the change in myocardial pH from preischemia, and the area of necrosis/area of risk (histochemical staining). Hearts protected with retrograde coronary sinus cardioplegia had less tissue acidosis (change in pH = 0.08 +/- 0.03 versus 0.41 +/- 0.13; p less than 0.05), higher wall motion scores (2.0 +/- 0.6 versus 1.3 +/- 0.3; not significant), and less myocardial necrosis (43.4% +/- 3.6% versus 73.3% +/- 3.5%; p less than 0.0001). We conclude that retrograde coronary sinus cardioplegia provides more optimal myocardial protection than is possible with antegrade cardioplegia after revascularization of an acute coronary occlusion.

Retrograde coronary sinus cardioplegia for aortic valve operations: a clinical report on 500 patients

Retrograde delivery of cardioplegic solutions has recently been the subject of renewed interest, but the reliability of this technique has not been assessed in large clinical series. From 1980 to 1989, we used retrograde coronary sinus perfusion as the exclusive means of cardioplegia delivery in 500 consecutive patients undergoing aortic valve replacement, either isolated (359 patients) or combined with another valve or coronary procedure (141 patients). The coronary sinus was always cannulated under direct vision after bicaval cannulation with snaring. Cold crystalloid cardioplegia was delivered retrogradely at an average flow rate of 100 mL/min in conjunction with topical and systemic (25 degrees C) hypothermia. The mean cross-clamp time was 83 +/- 23 minutes (+/- the standard deviation). There were 31 hospital deaths (6.2%), 20 of which were cardiac related. Transient hemodynamic instability (defined as a need for inotropic agents for less than 24 hours postoperatively) occurred in 16 patients (3.2%), whereas a true low-output syndrome developed in 60 patients (12%). The incidence of clinically significant supraventricular arrhythmias and of permanent conduction defects was 7.4% and 1.2%, respectively. There were three nonfatal coronary venous injuries during our early experience. We conclude that coronary sinus perfusion is a safe and effective means of delivering cardioplegia in aortic valve operations. While providing a degree of myocardial protection similar to that reported with anterograde cardioplegia, the coronary sinus technique offers distinct advantages, in particular, the avoidance of perfusion-related coronary artery complications and the opportunity to repeat cardioplegia administration without interrupting the procedure.(ABSTRACT TRUNCATED AT 250 WORDS)