Retrograde coronary sinus perfusion: a safe alternative for ensuring cardioplegic delivery in aortic valve surgery

Acute Myocardial Infarction Due to Left Main Trunk Ostial Stenosis Occurring in the Acute Phase After Aortic Valve Replacement

Coronary ostial stenosis is a rare but critical complication after aortic valve replacement. We present a patient with acute myocardial infarction that occurred eight days after aortic valve replacement. The patient had favorable progress until eight days after the operation, but she suddenly developed ventricular fibrillation and then pulseless electrical activity; thus, she was placed on venoarterial extracorporeal membrane oxygenation. Emergent coronary angiography revealed severe stenosis without thrombus nor dissection in the left main trunk orifice, and we realized that the prosthetic valve stent was quite close to the left main trunk orifice. She underwent stent implantation, and TIMI III flow was achieved. She could be weaned from venoarterial extracorporeal membrane oxygenation in 12 days and was stabilized without inotropes. Unfortunately, she was complicated by fungal sepsis and died from multi-organ failure 37 days after index surgery. The majority of coronary ostial stenosis is reported to occur within a few months after surgery because of its pathophysiological mechanisms. The onset of coronary ostial stenosis in the acute phase after surgery like in our case is not common. The deformity of the aortic complex after aortic valve replacement may trigger a left main trunk ostial stenosis. The change of aortic complex geometry after aortic valve replacement should be noted, especially in small patients or narrow aortic annulus.

A Reproducible and Effective Technique for Coronary Sinus Injury Repair

Objective: Coronary sinus injury related to the use of a retrograde cardioplegia catheter is a rare but potentially life-threatening complication with mortality reported as high as 20%. We present a series of iatrogenic coronary sinus injuries as well as an effective method of repair without any ensuing mortality. Methods: There were 3,004 cases that utilized retrograde cardioplegia at our institution from 2007 to 2018. Of these, 15 patients suffered a coronary sinus injury, an incidence of 0.49%. A pericardial roof repair was performed in 14 cases in which autologous pericardium was sutured circumferentially to normal epicardium around the injury with purified bovine serum albumin and glutaraldehyde injected into the newly created space as a sealant. Incidence of perioperative morbidity and mortality, operative time, and length of stay were collected. Results: In our series, there were no intraoperative or perioperative mortalities. Procedure types included coronary artery bypass grafting (CABG), valve replacement and repair, or combined CABG and valve procedures. Median (interquartile range) cross-clamp time was 100 (88 to 131) minutes, cardiopulmonary bypass duration was 133 (114 to 176) minutes, and length of stay was 6 (4 to 8) days. None of the patients returned to the operating room for hemorrhage, and there were no complications associated with the repair of a coronary sinus injury when using the pericardial roof technique. Conclusions: Coronary sinus injuries can result in difficult to manage perioperative bleeding and potentially lethal consequences from cardiac manipulation. Our series supports the pericardial roof technique as an effective solution to a challenging intraoperative complication.

Myocardial protection in cardiac surgery: how limited are the options? A comprehensive literature review

For patients undergoing cardiopulmonary bypass, myocardial protection is a key for successful recovery and improved outcomes following cardiac surgery that requires cardiac arrest. Different solutions, components and modes of delivery have evolved over the last few decades to optimise myocardial protection. These include cold and warm and blood and crystalloid solution through antegrade, retrograde or combined cardioplegia delivery approach. However, each method has its own advantages and disadvantages, posing a challenge to establish a gold-standard cardioplegic solution with an optimised mode of delivery for enhanced myocardial protection during cardiac surgery. The aim of this review is to provide a brief history of the development of cardioplegia, explain the electrophysiological concepts behind myocardial protection in cardioplegia, analyse the current literature and summarise existing evidence that warrants the use of varying cardioplegic techniques. We provide a comprehensive and comparative overview of the effectiveness of each technique in achieving optimal cardioprotection and propose novel techniques for optimising myocardial protection in the future.

Engineered Biomaterials to Enhance Stem Cell-Based Cardiac Tissue Engineering and Therapy

Cardiovascular disease is a leading cause of death worldwide. Since adult cardiac cells are limited in their proliferation, cardiac tissue with dead or damaged cardiac cells downstream of the occluded vessel does not regenerate after myocardial infarction. The cardiac tissue is then replaced with nonfunctional fibrotic scar tissue rather than new cardiac cells, which leaves the heart weak. The limited proliferation ability of host cardiac cells has motivated investigators to research the potential cardiac regenerative ability of stem cells. Considerable progress has been made in this endeavor. However, the optimum type of stem cells along with the most suitable matrix-material and cellular microenvironmental cues are yet to be identified or agreed upon. This review presents an overview of various types of biofunctional materials and biomaterial matrices, which in combination with stem cells, have shown promises for cardiac tissue replacement and reinforcement. Engineered biomaterials also have applications in cardiac tissue engineering, in which tissue constructs are developed in vitro by combining stem cells and biomaterial scaffolds for drug screening or eventual implantation. This review highlights the benefits of using biomaterials in conjunction with stem cells to repair damaged myocardium and give a brief description of the properties of these biomaterials that make them such valuable tools to the field.

Hyponatremia and Hyperglycemia during Cardiopulmonary Bypass Related to Cardioplegia Solution

Alterations of sodium and glucose concentration may result from disorders of the normal regulatory mechanisms or from excessive intake of glucose, sodium, or free water. In children, hyponatremia most commonly results from excessive free water intake, frequently combined with inadequate sodium intake. The author reports a child who developed hyponatremia and hyperglycemia during cardiopulmonary bypass that was eventually attributed to the large volume of cardioplegia solution that was used. When excess free water administration is suspected as the etiology of hyponatremia, all possible sources should be considered.

A retrospective analysis of myocardial preservation techniques during coronary artery bypass graft surgery: are we protecting the heart?

Background

Retrograde perfusion into coronary sinus during coronary artery bypass graft (CABG) surgery reduces the need for cardioplegic interruptions and ensures the distribution of cardioplegia to stenosed vessel territories, therefore enhancing the delivery of cardioplegia to the subendocardium. Peri-operative myocardial injury (PMI), as measured by the rise of serum level of cardiac biomarkers, has been associated with short and long-term clinical outcomes. We conducted a retrospective analysis to investigate whether the combination of antegrade and retrograde techniques of cardioplegia delivery is associated with a reduced PMI than that observed with the traditional methods of myocardial preservation.

Methods

Fifty-four consecutive patients underwent CABG surgery using either antegrade cold blood cardioplegia (group 1, n = 28) or cross-clamp fibrillation (group 2, n = 16) or antegrade retrograde warm blood cardioplegia (group 3, n = 10). The study primary end-point was PMI, evaluated with total area under the curve (AUC) of high-sensitivity Troponin-T (hsTnT), measured pre-operatively and at 6, 12, 24, 48 and 72 hours post-surgery. Secondary endpoints were acute kidney injury (AKI) and inotrope scores, length of intensive care unit (ICU) and hospital stay, new onset atrial fibrillation (AF) and clinical outcomes at 6 weeks (death, non-fatal myocardial infarction, coronary artery revascularization, stroke).

Results

There was evidence that mean total AUC of hsTnT was different among the three groups (P = 0.050). In particular mean total AUC of hsTnT was significantly lower in group 3 compared to both group 1 (-16.55; 95% CI: -30.08, -3.01; P = 0.018) with slightly weaker evidence of a lower mean hsTnT in group 3 when compared to group 2 (-15.13; 95% CI -29.87, -0.39; P = 0.044). There was no evidence of a difference when comparing group 2 to group 1 (-1.42,; 95% CI: -12.95, 10.12, P = 0.806).

Conclusions

Our retrospective analysis suggests that, compared to traditional methods of myocardial preservation, antegrade retrograde cardioplegia may reduce PMI in patients undergoing first time CABG surgery.

Electronic supplementary material

The online version of this article (doi:10.1186/s13019-014-0184-7) contains supplementary material, which is available to authorized users.

Minimally invasive valve surgery

Cardiac valve surgery is life saving for many patients. The advent of minimally invasive surgical techniques has historically allowed for improvement in both postoperative convalescence and important clinical outcomes. The development of minimally invasive cardiac valve repair and replacement surgery over the past decade is poised to revolutionize the care of cardiac valve patients. Here, we present a review of the history and current trends in minimally invasive aortic and mitral valve repair and replacement, including the development of sutureless bioprosthetic valves.

Myocardial protection in cardiac surgery: a historical review from the beginning to the current topics

Myocardial protection has become an essential adjunctive measure in cardiac surgery for a couple of decades, because since the 1950s, the methods of cardioprotection (cardioplegic solutions and related procedures) have been improved by the mechanism of myocardial ischemia/reperfusion-induced damage being unveiled through the untiring efforts of researchers and clinicians. The concept of myocardial protection in cardiac surgery was proposed along with introduction of hypothermic crystalloid potassium cardioplegia in the beginning and has been diversified by pharmacological additives, blood cardioplegia, temperature modulation (warm; tepid), retrograde cardioplegia, controlled reperfusion, integrated cardioplegia, and pre-and postconditioning. This historical review summarized experimental and clinical studies dealing with the methods and results of myocardial protection in cardiac surgery, introducing the newly developed concepts for the last decade and the current topics.

Surgical Management of Minimally Invasive Aortic Valve Operations

Although there is still a role for conventional sternotomy for aortic valve replacement, minimally invasive techniques are increasing in popularity and may benefit the patient with shorter postoperative course, less morbidity, and decreased overall cost. Additionally, transcatheter procedures have recently shown promising results in high-risk patients. This article provides an overview of the development of minimally invasive aortic valve operations, including a brief history of minimally invasive approaches, surgical considerations during minimally invasive aortic valve replacement, and the technical approach to performing a hemisternotomy with aortic valve replacement. In addition, the authors review transcatheter techniques, including aortic valve replacement via a sheath placed in the apex of the left ventricle or through a sheath placed in the femoral vessels. Finally, the exciting results of the PARTNER trial and the effect of these results on the future of aortic valve surgery are discussed.

Beating heart continuous coronary perfusion for valve surgery: what next for clinical trials?

Prior to the introduction of cardioplegia, beating heart continuous coronary perfusion (BHCCP) was the only available method of myocardial protection. Currently, cardiac surgery on cardiopulmonary bypass with cardioplegic arrest is the gold standard strategy. Cardioplegic arrest provides an easier and safer way to operate on a still heart. It enables the performance of a broader range of cardiac procedures, and avoids the potential difficulties of continuous perfusion on a beating heart. Despite the overall effectiveness and safety of cardioplegia, some adverse effects remain, mainly due to the insult of ischemia, which results in ischemic reperfusion injury. As a result BHCCP has seen a revival as an alternative to cardioplegia for performing complex valvular surgery. Increasing experience reporting safety and efficacy of BHCCP is being published. However, despite the reported advantages, current available evidence validating safety and efficacy of BHCCP is controversial. This article provides an overview of BHCCP highlighting the current best available evidence supporting this strategy, concerns, controversies and potential areas for further research.

Trans-Coronary-Venous Interventions

The coronary venous system is routinely targeted during electrophysiological measurements or cardiac resynchronization therapy. However, several novel interventional techniques require coronary venous catheterization and visualization as well as transvenous delivery of devices and/or therapeutic agents. Recent reports suggest the possibility of a transvenous approach for the interventional treatment of refractory angina and mitral valve regurgitation. In addition, the coronary venous system has been used as a route for the delivery of stem cells in patients with left ventricular dysfunction due to ischemic heart disease. We review the potential value of using a coronary venous approach in association with recent therapeutic developments in the interventional treatment of structural and ischemic heart disease. We will also discuss techniques related to coronary venous catheterization.

Anatomical Variations of the Coronary Sinus Ostium Area of the Human Heart

Classic anatomical dissection of 150 heart specimens from adults aged 18–80 years was performed. The Thebesian valve was absent in 20% of cases and, in these, 4% had a large ostial valve of the middle cardiac vein in front of the coronary sinus ostium. Fibres of Chiari were found in 10% of cases. Ostia of the middle cardiac vein, posterior veins of the left ventricle, small cardiac vein and deep cardiac veins were present in the distal 10 mm of the coronary sinus. Some samples had ostial and/or parietal valves or antivalves that sometimes contained muscular fibres. Distal accessory parietal valves (2%) and antivalves (1%) of the coronary sinus wall were found at a distance of 4–7 mm from its ostium. The frequency and variability of anatomical structures in the area of the coronary sinus ostium probably influence the haemodynamics of this area. Knowledge of and being able to identify these anatomical variations may help in identifying and overcoming potential difficulties in treating arrythmias and in cardiosurgery.

Does normothermic normokalemic simultaneous antegrade/retrograde perfusion improve myocardial oxygenation and energy metabolism for hypertrophied hearts?

BACKGROUND

Beating-heart valve surgery appears to be a promising technique for protection of hypertrophied hearts. Normothermic normokalemic simultaneous antegrade/retrograde perfusion (NNSP) may improve myocardial perfusion. However, its effects on myocardial oxygenation and energy metabolism remain unclear. The present study was to determine whether NNSP improved myocardial oxygenation and energy metabolism of hypertrophied hearts relative to normothermic normokalemic antegrade perfusion (NNAP).

METHODS

Twelve hypertrophied pig hearts underwent a protocol consisting of three 20-minute perfusion episodes (10 minutes NNAP and 10 minutes NNSP in a random order) with each conducted at a different blood flow in the left anterior descending coronary artery (LAD [100%, 50%, and 20% of its initial control]). Myocardial oxygenation was assessed using near-infrared spectroscopic imaging. Myocardial energy metabolism was monitored using localized phosphorus-31 magnetic resonance spectroscopy.

RESULTS

With 100% LAD flow, both NNAP and NNSP maintained myocardial oxygenation, adenosine triphosphate, phosphocreatine, and inorganic phosphate at normal levels. When LAD flow was reduced to 50% of its control level, NNSP resulted in a small but significant decrease in myocardial oxygenation and phosphocreatine, whereas those measurements did not change significantly during NNAP. With LAD flow further reduced to 20% of its control level, both NNAP and NNSP caused a substantial decrease in myocardial oxygenation, adenosine triphosphate, and phosphocreatine with an increase in inorganic phosphate. However, the changes were significantly greater during NNSP than during NNAP.

CONCLUSIONS

Normothermic normokalemic simultaneous antegrade/retrograde perfusion did not improve, but slightly impaired myocardial oxygenation and energy metabolism of beating hypertrophied hearts relative to NNAP. Therefore, NNSP for protection of beating hypertrophied hearts during valve surgery should be used with extra caution.

Anatomical peculiarities of the cavo-tricuspid isthmus in the human heart

The cavo-tricuspid isthmus is the term for the part of the right atrium between the ostium of the inferior vena cava and its border--the Eustachian ridge on one side and the tricuspid valve on the other side. In this area lie the coronary sinus ostium with its Thebesian valve, the fibers of Chiari (10%), and ostia of the deep cardiac veins--the Thebesian veins in close relation to the coronary sinus ostium (35%). Pacing of the coronary sinus is very often used during the treatment of cardiac arrhythmias; radiofrequency catheter ablation in cases of permanent atrial tachycardia is successfully performed through the coronary sinus; during certain cardiosurgical procedures, cardioplegia is performed by retrograde perfusion of the myocardium through the coronary sinus. Knowing and recognizing certain anatomical peculiarities of the structures in this part of the right atrium may be interesting for clinical practice.

Cardiomyocyte Apoptosis After Antegrade and Retrograde Cardioplegia

BACKGROUND

Retrograde cardioplegia alone is often used in aortic valve and aortic root surgery. Due to the differences in venous anatomy between the right and the left side of the heart, retrograde cardioplegia is associated with incomplete protection of the right side. Since some apoptotic cardiomyocyte death is inevitable during an open heart surgery, we compared the extent of cardiomyocyte apoptosis in the left and right ventricles after antegrade and retrograde cardioplegia in a pig ischemia-reperfusion model.

METHODS

Pigs (n = 16, mean weight 30 kg) were openly assigned into the groups of antegrade and retrograde cardioplegia. After aortic cross-clamping, 500 mL of cold crystalloid (modified St Thomas) cardioplegia was administered into the ascending aorta or the coronary sinus. Aortic cross-clamp time was 30 minutes. Cardiomyocyte apoptosis was measured using the terminal transferase mediated ddUTP nick end-labeling (TUNEL) assay and immunohistochemical (IHC) staining for active caspase-3 in myocardial biopsies obtained before ischemia and after 90 minutes of reperfusion.

RESULTS

Apoptotic cardiomyocytes were significantly increased after ischemia-reperfusion as shown by both the TUNEL assay and caspase-3 activation. In the right ventricle, retrograde cardioplegia was associated with a 3.4-fold higher amount (TUNEL assay) of apoptotic cardiomyocytes as compared with antegrade cardioplegia (0.107% vs 0.032%, p < 0.05). A similar difference was also found in the left ventricle, although at a lower level (0.027% vs 0.012%, p < 0.05).

CONCLUSIONS

Increased apoptotic death of cardiomyocytes after retrograde cardioplegia as compared with the antegrade procedure implicates that retrograde cardioplegia alone provides inferior cardioprotection against irreversible ischemia-reperfusion injury both in the right and the left ventricle.

Direct cannulation of the coronary ostia

Direct cannulation of the coronary ostia is a technique used by many surgeons in aortic valve surgery, especially when the valve is incompetent. It is safe and feasible, but the small risk of it causing a potentially devastating ostial stenosis must be kept in mind.

Coronary Ostial Stenosis After Aortic Valve Replacement, Revisited

Coronary artery occlusive disease that develops after an uncomplicated aortic valve replacement is well recognized. We present a case that required two further coronary operations and two salvage angioplasty procedures for a continuing fibrotic process in the ascending aorta. The literature and pathology are reviewed.

The anatomic variability of the coronary vasculature of the human heart — Part II: some anatomical peculiarities of arteriovenous relations

The arteriovenous relations in human heart are, in some instances, different from arteriovenous relations in other parts of the body. The specific relations between cardiac arteries and veins may enable diffusible substances carried through the system of juxta-arterial cardiac veins to influence the regulation of the lumen of the coronary arteries. Arteriovenous anastomoses (6% of our 150 cases) permit direct communication between the arteries and veins bypassing the capillary circulation; it is assumed that these anastomoses prevent coagulation of blood in small veins. In cases of arterial occlusion, the myocardium is supplied by veins that allow retrograde vascularization of the myocardium. In 33% of our cases the posterior atrial branches (0.5-1.0 mm in diameter) of the coronary arteries ran through the wall of the coronary venous sinus on their way from the parent vessel, which lay in the coronary sulcus, to the left atrium. In 11% of the cases, the arterial branch that ran through the distal portion of the wall of the coronary sinus was the interatrial branch. The blood flow through the parietal arteries of the venous coronary sinus probably depends on the condition of the muscular layer of the sinus during the phases of cardiac action, and this might be important in the course of certain cardiosurgical procedures.

Clinical experience with coronary sinus catheterization in minimally invasive aortic valve surgery under transesophageal echocardiography guidance

We aimed to show conventional coronary sinus (CS) catheter could be used with transesophageal echocardiography (TEE) guidance through the limited surgical field in aortic valve surgery with 'J' sternotomy. This method was performed in 14 patients and completed successfully in 12. We believe that in minimally invasive aortic valve surgery, the insertion of the conventional retrograde cardioplegia catheter to the CS with routine way may not be possible but application of TEE guidance is cost-effective and easily applicable method without significant complications.

Coronary sinus rupture with retrograde cardioplegia

Coronary sinus (CS) rupture occurring during retrograde cardioplegia (RCP) is a rare complication. Patients with left ventricular hypertrophy are at higher risk for injury to the CS. The patient was a 66-year-old female with hypertension, ischemic cardiomyopathy and dysrhythmias, who had evidence of an anterior wall myocardial infarction, congestive heart failure and angina. During coronary artery bypass surgery, antegrade cardioplegia was initially administered, but aortic insufficiency prevented adequate myocardial cooling. RCP was then administered and the heart cooled appropriately. After approximately 300 ml of blood cardioplegic solution had been given, the CS pressure suddenly dropped from 30 mmHg to zero. RCP administration was stopped, and the surgeon palpated a hematoma over the area of the CS, which later ruptured upon rotation of the heart. A primary repair could not be performed, so a pericardial patch was placed over the area of disruption, which appeared to provide adequate hemostasis. The patient was weaned from cardiopulmonary bypass (CPB), but began to bleed freely from the CS distal to the pericardial patch. The patient was placed back on CPB to allow further repair of the CS, but the tissues were thin and friable and the ventricle disassociated from the ventricular septum. The situation was deemed not salvageable and further attempts at repair were stopped. The perfusionist should monitor infusion pressures and the CS waveform during RCP delivery. Changes in the waveform may indicate cannula malposition, loss of balloon seal, or, more rarely, CS rupture; such changes should prompt immediate cessation of RCP delivery.

Investigation of coronary venous anatomy by retrograde venography in patients with malignant ventricular tachycardia

BACKGROUND

The coronary venous system is increasingly used for left ventricular or biventricular pacing in patients with severe heart failure. The present study investigated the structure of the coronary veins in patients presenting with structural heart disease and malignant ventricular tachyarrhythmias. The availability of veins for possible lead placement was assessed.

METHODS AND RESULTS

The number, relative size, and location of coronary veins were evaluated by retrograde venography in 129 patients undergoing cardioverter-defibrillator implantation. Detailed x-ray image analysis was performed in 86 patients, for whom optimal coronary sinus occlusion and vein visualization was achieved. The anterior interventricular vein and the middle cardiac vein were visible in 85 (99%) of 86 patients and in 86 (100%) of 86 patients, respectively. Between these 2 veins, at least 1 additional prominent vein was visible in 85 (99%) of 86 patients. Just 1 vein was present in 44 (51%) of 86 patients. Two veins were observed in 40 (46%) of 86 patients, and >2 veins were visualized in 2 (2%) of 86 patients. Venous anatomy allowed positioning of a 0.014-in guidewire in a coronary vein in 115 (93%) of 124 patients.

CONCLUSIONS

The presence, diameter, angulation, and tortuosity of veins as visualized by retrograde venography determine their acceptability for the placement of a lead in a predetermined location. Despite the considerable variability of the coronary venous system among patients, a lateral vessel for lead introduction was available in 82%, and a posterior or lateral vessel was available in 99% of individuals within a patient population that could potentially benefit from a lead on the left ventricle.

Cardioplegia flow dynamics in an in vitro model

The flow of fluids in extracorporeal circuits does not conform to conventional Poiseuille mechanics which confounds calculating cardioplegia (CP) flow distribution. The purpose of this study was to quantify CP flow dynamics in a model simulating coronary atherosclerosis across varying sized restrictions. An in vitro preparation was designed to assess hydraulic fluid movement across paired restrictions of 51, 81 and 98% lumen reductions. Volume data were obtained at variable flow, temperature, viscosity and pressure conditions. CP delivered through 14- and 18-gauge (GA) conduits at 8 degrees C and 100 mmHg infusion pressure revealed that both four to one and crystalloid CP solutions had significantly less total percentage flow through the 14-GA conduit, p < 0.0001 and p < 0.001, respectively. Overall, 4:1 CP exhibited the most favorable fluid dynamics at 8 degrees C in that it delivered the highest percentages of total CP flow through the smaller lumen conduit. At both 8 degrees C and 37 degrees C delivery, blood CP resulted in the least homogeneous fluid distribution at all delivery parameters. The results in relation to blood viscosity indicate that, although the 8 degrees C blood CP had a significantly greater viscosity than 37 degrees C blood CP, it did not produce an effect in fluid distribution. These data show that increasing the cardioplegic solution hematocrit causes an inhomogeneous fluid distribution regardless of delivery temperature or infusion pressure.

Percutaneous coronary sinus cannulation guided by transesophageal echocardiography

We investigated whether percutaneous cannulation of the coronary sinus could be accomplished without fluoroscopy using transesophageal echocardiography in patients undergoing minimally invasive cardiac operations. The coronary sinus was cannulated without significant complications using transesophageal echocardiography in 10 of 11 patients (mean, 10.5 minutes). Percutaneous cannulation of the coronary sinus can be accomplished in a safe and efficient manner using transesophageal echocardiography without the need for fluoroscopy.

Antegrade-Retrograde Cardioplegia for Myocardial Protection during Coronary Artery Bypass Graft Surgery

This prospective randomized clinical study was designed to assess and compare the use of combined antegrade-retrograde cardioplegia versus antegrade cardioplegia in providing adequate myocardial preservation during coronary artery bypass graft surgery. Fifty patients undergoing elective coronary artery bypass grafting were randomly divided into 2 groups according to the route of cardioplegic delivery: group A (25 patients) received antegrade cold crystalloid cardioplegia; group B (25 patients) received combined antegrade-retrograde cold crystalloid cardioplegia. The groups were compared by clinical and electrocardiographic criteria and biochemical markers of ischemic myocardial damage. There was a highly significant statistical difference between the groups in terms of spontaneous recovery of sinus rhythm (40% of patients in group A versus 96% in group B). The use of direct current shock to restore sinus rhythm was higher in group A (60%) compared with group B (4%). Low cardiac output occurred in 20% of patients in group A and in 16% of patients in group B but this difference was not statistically significant. No bundle-branch block was found in group B whereas the incidence was 8% in group A. Significantly higher levels of biochemical markers of myocardial damage were obtained in group A at 10 minutes, 4 hours, and 12 hours after declamping. These results indicate that combined antegrade-retrograde cardioplegia is superior to antegrade cardioplegia for myocardial protection during coronary artery bypass graft surgery.

Retrograde coronary perfusion: effects on iatrogenic edema and diastolic properties

BACKGROUND

The relative merits of antegrade infusion and retrograde infusion of cardioplegic solution in terms of heart weight, myocardial water content, and ventricular diastolic properties are undefined. Accordingly, we compared antegrade and retrograde flow of hemodiluted blood in isolated, hypothermic porcine hearts.

METHODS

After cardiectomy, 1 L of cold heparinized blood diluted with lactated Ringer's solution to concentrations ranging from 100% lactated Ringer's to 50% lactated Ringer's and 50% blood was perfused in an antegrade (n = 6) or retrograde (n = 6) fashion at mean pressures of 62 +/- 2 mm Hg (+/- standard error of the mean) and 49 +/- 2 mm Hg, respectively. Heart weight, myocardial water content, and left ventricular pressure-volume relationships were obtained before and after perfusion.

RESULTS

In the comparison of measurements before and after perfusion, changes in heart weight (36 +/- 4 g versus 5 +/- 2 g; p < 0.05), myocardial water content (6.9% +/- 1.0% versus 2.5% +/- 0.4%; p < 0.01), and ventricular filling measured by normalized left ventricular volume at 10, 15, and 20 mm Hg were greater in the antegrade group.

CONCLUSIONS

In the isolated porcine heart, retrograde flow is distinguished from antegrade flow by less change in heart weight and myocardial water content and no diastolic dysfunction.

Assessment of retrograde cardioplegia with magnetic resonance imaging and localized 31P spectroscopy in isolated pig hearts

OBJECTIVE

This study was done to determine whether retrograde delivery of cardioplegic solution provides uniform blood flow to the myocardium supplied by an occluded coronary artery and whether it maintains myocardial energy levels beyond the coronary occlusion.

METHODS

Isolated pig hearts were used. A hydraulic occluder was placed at the origin of the left anterior descending coronary artery. The perfusion pressure for retrograde delivery of cardioplegic solution was controlled at 40 to 50 mm Hg. Magnetic resonance imaging and localized 31P magnetic resonance spectroscopy were used to assess myocardial perfusion and energy metabolism, respectively.

RESULTS

Magnetic resonance perfusion images (n = 7) showed that the perfusion defect that occurred during antegrade delivery of cardioplegic solution (as a result of the occlusion of the left anterior descending coronary artery) resolved during retrograde delivery of cardioplegic solution. Retrograde perfusion delivered similar amounts of flow to the jeopardized myocardium as it did to other areas of the myocardium. However, the distribution of cardioplegic solution by the retrograde route was heterogeneous (cloudlike) across both ventricular walls. 31P magnetic resonance spectra showed that the ischemic changes induced by occlusion of the left anterior descending artery during antegrade perfusion were greatly alleviated by retrograde perfusion; however, it took longer for retrograde cardioplegia (n = 7, 17.08 minutes) to restore the levels of inorganic phosphate/phosphocreatine relative to the effect of releasing the left anterior descending artery occluder during antegrade delivery of cardioplegic solution (n = 7, 5.3 minutes).

CONCLUSIONS

First, retrograde delivery of cardioplegic solution provides sufficient flow to the myocardium beyond a coronary occlusion to maintain near normal levels of energy metabolites, and second, the efficacy of the retrograde route of cardioplegic solution delivery (in terms of distribution of the solution and rate of myocardial energy recovery) is significantly lower than that of the antegrade route.

Recent Developments in Myocardial Protection: Retrograde Cardioplegia

In recent years there has been increasing use of coronary sinus perfusion to deliver cardioplegic solutions during open-heart surgery. This has been aided by advances in coronary sinus catheter design and by easier methods of cannula insertion. Coronary sinus perfusion has been used with both intermittent crystalloid and blood cardioplegia and has recently evolved to include retrograde continuous normothermic blood cardioplegia. Coronary sinus perfusion has several advantages including safety, ease of use (with a single cannula placed out of the operative field), usefulness in patients with significant aortic regurgitation, redo coronary artery bypass graft surgery, and acute myocardial infarction. However, there are continuing concerns about the distribution of retrograde perfusion, preservation of right ventricular function, dislodgment of the coronary sinus catheter (and resulting ischemia during surgery), and damage to the coronary sinus.

Angiographic and electron-beam computed tomography studies of retrograde cardioplegia via the coronary sinus

Retroperfusion of the coronary sinus does not provide homogeneous distribution of cardioplegic solution. The goal of this study was to analyze the distribution of flow during retrograde cardioplegic infusion in cadaveric human hearts with two different techniques of coronary sinus cannulation: (1) internal occlusion of the coronary sinus by balloon inflation and (2) external occlusion by tightening the orifice of the coronary sinus around a simple catheter. To evaluate differences between the two techniques, angiographic and electron-beam computed tomographic studies were performed. Computed digital angiography was performed on 14 hearts. Angiographic patterns varied according to type of coronary sinus cannulation. With the balloon inflation technique, the marginal vein and the anterior descending vein were perfused first; the posterior descending vein was not perfused. This vein was opacified secondarily through a venovenous anastomosis located at the apex of the heart. Backward flow into the right atrium (steal phenomenon) was demonstrated. At completion of retroperfusion, the inferior part of the septum remained poorly opacified. Conversely, angiographic findings after external occlusion of the coronary sinus revealed simultaneous injection of all venous channels. The entire septum was well opacified at completion of retroperfusion. Electron-beam computed tomographic study was performed on eight hearts with the external occlusion technique and nine with the internal occlusion technique. The computed tomographic findings confirmed the results of digital angiography. The peak myocardial enhancement and the peak rising rate of myocardial enhancement within the interventricular septum were significantly more important (p < 0.0001) when the external coronary sinus occlusion mode was used than when the internal coronary sinus occlusion mode was used. In all hearts except one, the right ventricular wall was not opacified, regardless of the type of cannulation and the type of radiologic analysis. This study demonstrates the importance of coronary sinus cannulation technique in optimizing the protection of the interventricular septum with retrograde cardioplegic infusion.

Can ischemic preconditioning ensure optimal myocardial protection when delivery of cardioplegia is impaired?

BACKGROUND

Ischemic preconditioning is a potent protective intervention that is effective in all species studied. We have previously shown it to be as effective as cardioplegia; however, we have also shown that their combined use does not afford greater protection than the use of either alone. In the present study we investigated whether coincident ischemic preconditioning could compensate for inadequate cardioplegic protection when the delivery of cardioplegia was impaired, such as occurs in the presence of severe coronary stenosis or occlusion.

METHODS AND RESULTS

Isolated rat hearts were subjected to 30 minutes of global ischemia followed by 40 minutes of reperfusion. Four groups of hearts (n = 12 per group) were studied: group 1, controls (no intervention); group 2, cardioplegia administered to hearts with a proximally occluded coronary artery; group 3, ischemic preconditioning applied before ischemia; and group 4, ischemic preconditioning and cardioplegia given in combination to hearts with a proximally occluded coronary artery. The postischemic recovery of left ventricular (LV) developed pressure (LVDP), expressed as a percentage of preischemic values, was significantly greater (P < .05) in preconditioned hearts (64 +/- 3%) than in control hearts (24 +/- 4%) or hearts treated with suboptimal cardioplegia (43 +/- 5%). Hearts with preconditioning plus cardioplegia recovered to an extent similar to that seen with preconditioning alone (59 +/- 2%). LV end-diastolic pressure was greater in control hearts (58 +/- 4 mm Hg) than in hearts with cardioplegia (41 +/- 4 mm Hg; P < .05 versus group 1) despite the incomplete delivery of the cardioplegia; the best protection was observed in preconditioned hearts and hearts with preconditioning plus cardioplegia (24 +/- 1 and 26 +/- 2 mm Hg, respectively; P < .05 versus groups 1 and 2).

CONCLUSIONS

When the delivery of cardioplegia was impaired, myocardial protection (postischemic LVDP) was better served by ischemic preconditioning. Under the same conditions, the combination of cardioplegia plus preconditioning afforded superior protection compared with cardioplegia alone. These results may be of clinical interest since most patients who undergo surgery for ischemic heart disease suffer from severe coronary artery lesions that can prevent the adequate delivery of cardioplegia.

Milestones in the development of cardioplegia

Long before there was a possibility for the application of cardioplegia to clinical situations, physiologists and surgeons studied the influence of various cations on function of the myocardial cell. These monumental studies helped set the stage for the eventual practical application of various means of myocardial preservation once open cardiac surgical techniques became available. This presentation attempts to summarize early research effort from the work of Sidney Ringer in 1878 until the present time. The historical progression of myocardial protective strategies is reviewed in a sequential fashion, highlighting major contributions and practices of investigators at the time. It is hoped that such a review of the accomplishments of our colleagues past and present will improve our perspective regarding current applications of such knowledge and that it may stimulate further inquiry toward improving present-day myocardial preservation strategies.

Retrograde-delivered cardioplegia is not distributed equally to the right ventricular free wall and septum

Right ventricular myocardial protection during cardiac surgery continues to be a challenge. Retrograde delivery of cardioplegia has been shown to perfuse left ventricular regions subtended by critical coronary stenosis and not adequately protected by antegrade delivery. However, the distribution of cardioplegia from the coronary sinus to the right ventricle remains in question. A reliable means for assessing such flow distribution intraoperatively is provided by contrast echocardiography. It was hypothesized that conventional use of coronary sinus catheters for retrograde cardioplegia delivery does not reliably perfuse the myocardial region subtended by the right coronary artery. Six patients scheduled to undergo elective coronary artery bypass surgery were evaluated with contrast echocardiography to determine the distribution of retrograde-delivered cardioplegia into the right ventricle. Sonicated Renografin-76 (Squibb Diagnostics, Princeton, NJ) was injected during retrograde delivery of cold crystalloid cardioplegia solution and continuous two-dimensional ultrasound imaging of the heart. On-line videodensitometric analysis was performed with a digital ultrasound system. The area under the curve and peak pixel intensity were determined for the anterior septum, the posterior septum, and the right ventricular free wall for each contrast injection. Recorded VHS videotape images of contrast-enhanced perfusion patterns were also reviewed and scored. On-line acoustic-densitometric analysis showed that right ventricular posterior and anterior septal peak pixel intensities were 4.8 +/- 3.2 and 7.3 +/- 1.5, respectively, compared with only 1.6 +/- 1.2 (p < or = 0.05) in the right ventricular free wall.(ABSTRACT TRUNCATED AT 250 WORDS)

Resection of subvalvular aortic stenosis. Surgical and perioperative management in seven dogs

Open heart surgery was performed during cardiopulmonary bypass (CPB) to surgically correct subvalvular aortic stenosis in seven dogs. After initiation of total CPB, cardiac arrest was induced by antegrade and retrograde administration of blood cardioplegia. The subvalvular fibrous stenosis was resected through a transverse aortotomy. Intraoperatively and postoperatively, dobutamine, nitroprusside, lidocaine, blood(-products), and crystalloid solutions were used to manage hypotension and optimize cardiac index. Aortic cross-clamp time varied from 73 to 166 minutes, and duration of CPB varied from 130 to 210 minutes. Iatrogenic incision into the mitral valve in two dogs was the most significant intraoperative complication. Postoperative complications included: hypoproteinemia (n = 7), premature ventricular depolarization (n = 6), increased systemic vascular resistance index (n = 5), increased O2 extraction (n = 3), pulmonary edema (n = 2), and decreased cardiac index (n = 1). All seven dogs were discharged alive and in stable condition. Six dogs are alive and in stable condition after a mean follow up of 15.8 months. This is the first detailed report of CPB in a series of clinical veterinary patients. Using the techniques described in this paper, open heart surgery of considerable duration can be performed successfully in dogs with significant myocardial hypertrophy and endomyocardial fibrosis secondary to subvalvular aortic stenosis.

Unusual complication of retrograde coronary sinus perfusion with pulmonary artery catheter

A balloon-tipped catheter placed in the coronary sinus is used during cardiac surgery for retrograde cardioplegia and is secured by a purse string suture placed proximal to the atrioventricular groove in the lower right atrium. We report a complication of this procedure where a pulmonary artery catheter was sutured to the wall of the right atrium by the purse string suture in a patient scheduled for aortocoronary bypass grafting. Pulsatile resistance was noted when we attempted to withdraw the catheter indicating an attachment to the heart. The pulmonary artery catheter within the vascular space after atrial cannulation should be checked since the sheath-protected cannula will enable free mobility.

Improved myocardial protection by antegrade perfusion in combination with coronary sinus occlusion in the presence of left anterior descending artery obstruction

The present study was undertaken to evaluate the improved protection of antegrade aortic root perfusion combined with intermittent coronary sinus occlusion (APCSO) for the 1-hour ischemic myocardium in the presence of left anterior descending artery occlusion, 12 dogs were divided into 2 groups: anteperfusion (AP) alone (n = 6) and APCSO (n = 6). The experimental results showed that APCSO provided a better cardioplegic distribution and a lower hypothermia (15.6 degrees C versus 17.2 degrees C) in the occluded LAD region, compared with AP. After ischemia, cardiac index and left ventricular stroke index recovered excellently in APCSO (128% to 141% and 115% to 158% of preischemic values, respectively), and much worse in AP (69% to 82% and 53% to 73% of preischemic values, respectively). Our study has confirmed that APCSO is superior to AP in myocardial protection in the presence of coronary artery occlusion.

Retrograde cardioplegia: when and how. A review

With the introduction of balloon catheters enabling blind transatrial cannulation of the coronary sinus, retrograde cardioplegia is gaining increasing popularity. In several situations retrograde cardioplegia offers distinct technical advantages. Although not yet clinically documented, some patient subgroups with severe coronary stenoses/occlusion may probably benefit from retrograde cardioplegia. This technique is a valuable addendum to the technical repertoire of cardiac surgeons.

Coronary sinus injuries during retrograde continuous normothermic blood cardioplegia

Injuries to the coronary sinus during cardioplegic arrest are rare but potentially lethal. We herein present case reports of injuries to the coronary sinus occurring during retrograde continuous normothermic blood cardioplegia, and emphasize preventive measures and treatment.

Retrograde versus antegrade cardioplegia: impact on right ventricular function

Retrograde cardioplegia administered through the coronary sinus has several documented advantages over antegrade cardioplegia but has been thought to provide inadequate right ventricular myocardial protection. We prospectively compared the effects of retrograde and antegrade cardioplegia on right ventricular performance in patients undergoing myocardial revascularization. Two groups of similar age, extent of disease, and preoperative left ventricular ejection fraction received retrograde (n = 16) or antegrade (n = 14) crystalloid cardioplegia. A right ventricular rapid-response thermistor catheter, previously developed and validated in our institution, was used to measure right atrial pressure, pulmonary artery pressure, right ventricular ejection fraction, end-diastolic volume index, and stroke volume index before bypass (baseline) and at several intervals after bypass. There were no differences in cross-clamp time, heart rate, cardiac enzymes, inotrope requirements, or arrhythmias between the two groups. Right ventricular parameters were equivalent in both groups at all time intervals except 30 minutes after bypass, at which time right ventricular end-diastolic volume index was lower (80 +/- 6 versus 93 +/- 6 mL/m2; p less than 0.05) and right ventricular stroke volume index was higher (35 +/- 3 versus 29 +/- 2 mL/m2, p less than 0.05) in the retrograde group compared with the antegrade group, indicating better right ventricular function with retrograde cardioplegia early after bypass. In both groups, right ventricular end-diastolic volume index was higher than baseline (p less than 0.05) during the first 4 hours after bypass. No other important differences were found.(ABSTRACT TRUNCATED AT 250 WORDS)