St. Thomas Modified Cardioplegia Effects on Myoblasts' Viability and Morphology.

Background and Objectives: The cardioplegic arrest of the heart during cardiosurgical procedures is the crucial element of a cardioprotection strategy. Numerous clinical trials compare different cardioplegic solutions and cardioprotective protocols, but a relatively small number of papers apply to in vitro conditions using cultured cells. This work aimed to analyze whether it is possible to use the rat heart myocardium cells as an in vitro model to study the protective properties of St. Thomas cardioplegia (ST2C). Methods: The rat heart myocardium cells-H9C2 were incubated with cold cardioplegia for up to 24 h. After incubation, we determined: viability, confluency, and cell size, the thiol groups' level by modifying Ellman's method, Ki67, and Proliferating Cell Nuclear Antigen expression (PCNA). The impact on cells' morphology was visualized by the ultrastructural (TEM) study and holotomograpic 3D imaging. Results: The viability and confluency analysis demonstrated that the safest exposure to ST2C, should not exceed 4h. An increased expression of Ki67 antigen and PCNA was observed. TEM and 3D imaging studies revealed vacuolization after the longest period of exposure (24). Conclusions: According to obtained results, we conclude that STC can play a protective role in cardiac surgery during heart arrest.

Effects of histidine load on ammonia, amino acid, and adenine nucleotide concentrations in rats.

The unique capability of proton buffering is the rationale for using histidine (HIS) as a component of solutions for induction of cardiac arrest and myocardial protection in cardiac surgery. In humans, infusion of cardioplegic solution may increase blood plasma HIS from ~ 70 to ~ 21,000 µM. We examined the effects of a large intravenous dose of HIS on ammonia and amino acid concentrations and energy status of the body. Rats received 198 mM HIS intravenously (20 ml/kg) or vehicle. Samples of blood plasma, urine, liver, and soleus (SOL) and extensor digitorum longus (EDL) muscles were analysed at 2 or 24 h after treatment. At 2 h after HIS load, we found higher HIS concentration in all examined tissues, higher urea and ammonia concentrations in blood and urine, lower ATP content and higher AMP/ATP ratio in the liver and muscles, higher concentrations of almost all examined amino acids in urine, and lower glycine concentration in blood plasma, liver, and muscles when compared with controls. Changes in other amino acids were tissue dependent, markedly increased alanine and glutamate in the blood and the liver. At 24 h, the main findings were lower ATP concentrations in muscles, lower concentrations of branched-chain amino acids (BCAA; valine, leucine, and isoleucine) in blood plasma and muscles, and higher carnosine content in SOL when compared with controls. It is concluded that a load of large HIS dose results in increased ammonia levels and marked alterations in amino acid and energy metabolism. Pathogenesis is discussed in the article.

Use of del Nido cardioplegia solution and a low-prime recirculating cardioplegia circuit in pediatrics.

The evolution of myocardial protection techniques has been both the source of milestone advancements and controversial debate in cardiac surgery. Our institution has modified a low-prime cardioplegia system (CPS) and adopted a single-dose cardioplegia solution (del Nido cardioplegia) for our congenital heart disease population. The goal of this article is to describe our CPS and outline our myocardial protection protocol. These techniques have allowed us to minimize circuit surface area, operate uninterrupted, and safely protect the myocardium during extended ischemic periods.

History and use of del Nido cardioplegia solution at Boston Children's Hospital.

Cardioplegia is an integral and essential method of myocardial protection for patients of all ages requiring cardiac surgery in which the heart must be stopped. Numerous cardioplegia solutions and delivery methods have been developed. The del Nido cardioplegia solution has been in use for 18 years at Boston Children's Hospital. This is a unique four parts crystalloid to one part whole blood formulation that is generally used in a single-dose fashion. Although the formulation was originally developed for use in pediatric and infant patients, its use for adult cardiac surgery has been expanding. National and international inquiries to our institution regarding this cardioplegia have been increasing over the last 2 years. We present the developmental history, supporting theory, and current protocol for use of what is now referred to as del Nido cardioplegia.

Single dose myocardial protection technique utilizing del Nido cardioplegia solution during congenital heart surgery procedures.

BACKGROUND: The single dose cardioplegia technique for myocardial protection during congenital heart surgery is a viable alternative to multidose protocols. METHODS: Thirty-four pediatric patients with aortic cross clamp times greater than 90 minutes were grouped by modified adult (MA) multidose solution or del Nido (dN) single dose solution. Also, data from eight patients where the cross clamp times were greater than two hours on one dose of dN solution were included. RESULTS: In the 90-minute plus arm of the study, there were no significant differences between the groups when comparing the risk adjustment for congenital heart surgery (RACHS) (p=0.6), cardiopulmonary bypass times (CPB) (p=0.5), aortic cross camp times (p=0.5), weights (p=0.7) and number of intraoperative exogenous blood units (p=0.5). There were significant differences between the groups (p<0.05) in the number of cardioplegia doses and with perioperative glucose levels. In the greater than two hours group, the incidence of complete heart block (CHB) was 0.125% and there were no deaths or mechanical circulatory support (MCS) devices used. CONCLUSION: del Nido cardioplegia solution is a reasonable tool for myocardial protection during congenital heart surgery that significantly decreased the number of cardioplegic interventions and perioperative glucose values in our study groups.

Blood cardioplegia serves as a bicarbonate donor to the myocardium during ischemia: effects of anoxia and hypercapnia on acid-base characteristics of blood cardioplegic solution.

OBJECTIVES: We investigated the alterations of acid-base characteristics of the blood cardioplegia (BCP) solution during aortic cross-clamping in hearts arrested with BCP and during in vitro-simulated ischemia. METHODS: Following aortic cross-clamping, the hearts of 40 patients undergoing cardiac surgery were intermittently infused with an 18°C BCP solution and finally with a 34°C BCP solution prior to aortic cross-clamp release. We measured the pH, partial CO(2) pressure (pCO(2)), [HCO(3)(-)], and [Cl(-)] of the coronary sinus effluent in the final BCP solution. The BCP solution was assessed under in vitro gassing at 34°C with 95% N(2) + 5% CO(2) (n = 6), 50% N(2) + 50% CO(2) (n = 3), or 100% CO(2) (n = 6). RESULTS: The coronary sinus effluent, compared with the preinfusion BCP solution, exhibited a significantly lower pH and a greater pCO(2) with no change in the [HCO(3)(-)] level. In vitro, the 95% N(2) + 5% CO(2) gassing (simulated hypoxia) group exhibited a slight increase in [HCO(3)(-)] with no change in pCO(2) or pH whereas the 50% N(2) + 50% CO(2) gassing and the 100% CO(2) gassing (simulated hypoxia and hypercapnia) groups exhibited a significant increase in [HCO(3)(-)] under high pCO(2)-induced acidification. CONCLUSIONS: Under anoxia and CO(2) retention during aortic cross-clamping, the BCP solution can be a bicarbonate donor to the myocardium.

[Solutions for organ preservation and other cardioplegic liquid formulations. Role of the hospital pharmacist]. / Solutions pour conservation d'organes et pour cardioplégie. Le rôle du pharmacien hospitalier.

Solid organ transplantation is an increasing need and a well-established activity which requires maintaining the quality of the transplant from procurement through the entire, storage, transport and graft procedure. Solutions for organ preservation play a key role in this procedure, by minimizing the deleterious effects of both ischemia and reperfusion. As such, their qualitative and quantitative compositions have to be optimized and validated. The development strategy and formulations proposed for these solutions are analyzed in this review as well as the results of the clinical studies which have set up the relevant pharmacological and physicochemical criteria. The French regulatory status of these products is also discussed. A clear distinction has to be made between solutions for organ preservation which are classified as produits thérapeutiques annexes (therapeutic ancillary products) and cardioplegic liquid formulations which are considered as medicinal products and are subject to marketing approval. Finally, the roles of the hospital pharmacist in the evaluation, selection, purchase and proper use of these products are described.

Lidocaine and Pinacidil Added to Blood versus Crystalloid Cardioplegic Solutions: Study in Isolated Hearts.

OBJECTIVE: The present study aimed the functional recovery evaluation after long term of cardiac arrest induced by Custodiol (crystalloid-based) versus del Nido (blood-based) solutions, both added lidocaine and pinacidil as cardioplegic agents. Experiments were performed in isolated rat heart perfusion models. METHODS: Male rat heart perfusions, according to Langendorff technique, were induced to cause 3 hours of cardiac arrest with a single dose. The hearts were assigned to one of the following three groups: (I) control; (II) Custodiol-LP; and (III) del Nido-LP. They were evaluated after ischemia throughout 90 minutes of reperfusion. Left ventricular contractility function was reported as percentage of recovery, expressed by developed pressure, maximum dP/dt, minimum dP/dt, and rate pressure product variables. In addition, coronary resistance and myocardial injury marker by alpha-fodrin degradation were also evaluated. RESULTS: At 90 minutes of reperfusion, both solutions had superior left ventricular contractile recovery function than the control group. Del Nido-LP was superior to Custodiol-LP in maximum dP/dt (46%±8 vs. 67%±7, P<0.05) and minimum dP/dt (31%±4 vs. 51%±9, P<0.05) variables. Coronary resistance was lower in del Nido-LP group than in Custodiol-LP (395%±50 vs. 307%±13, P<0.05), as well as alpha-fodrin degradation, with lower levels in del Nido-LP group (P<0.05). CONCLUSION: Del Nido-LP cardioplegia showed higher functional recovery after 3 hours of ischemia. The analysis of alpha-fodrin degradation showed del Nido-LP solution provided greater protection against myocardial ischemia and reperfusion (IR) in this experimental model.

Adenosine instead of supranormal potassium in cardioplegic solution improves cardioprotection.

OBJECTIVE: To determine whether adenosine instead of supranormal potassium in cold crystalloid cardioplegia gives satisfactory cardiac arrest and improved cardioprotection. Cold crystalloid cardioplegia with adenosine, procaine and magnesium (A) was compared with standard cold crystalloid hyperkalemic cardioplegia (K). METHODS: Sixteen pigs were randomized to receive either cold K (n=8) or A (n=8), where hyperkalemia was substituted with 1.2 mM adenosine. The cold (6 degrees C) cardioplegia was given intermittently and antegradely, with an aortic cross-clamp time of 1 h. Hemodynamic data was continuously measured and pressure-volume conductance catheters were used to determine global left ventricular systolic and diastolic function. Coronary flow and O2 content differences allowed determination of left ventricular energetics. Blood samples, and left ventricular microdialysis were used to measure parameters of ischemia. Measurements were done at 1 and 2 h after cross-clamp release. RESULTS: Mean arterial pressure was reduced with 55 mmHg (standard deviation, SD: 19) in the K group versus 30 mmHg (SD: 14) in the A group 2 h after cross-clamp release (p=0.030). Left ventricular contractility expressed as slope of the preload recruitable stroke work index (Mw) was reduced to 53% (SD: 14) in the K group versus 78% (SD: 23) in the A group 2h after cross-clamp release (p=0.046). Reduction of maximum of first derivate of pressure with respect to time (dP/dtmax) was 804 mmHg/s (SD: 189) in the K group versus 538 mmHg/s (SD: 184) in the A group (p=0.033). The slope of the myocardial oxygen consumption-pressure volume area was at 2 h reperfusion increased from 1.37 (SD: 0.64) to 2.86 (SD: 1.27) in the K group, whereas no shift was detected in the A group (p=0.019). Cardiac troponin T measured in the coronary sinus 1 h after cross-clamp release was 1.25 microg/l (SD: 0.64) in the K group versus 0.73 microg/l (SD: 0.31) in the A group (p=0.046). CONCLUSION: Adenosine instead of supranormal potassium in cold crystalloid cardioplegia gives satisfactory cardiac arrest, improves post cardioplegic left ventricular systolic function and efficiency, and attenuates myocardial cell damage.

Comparing del Nido and Conventional Cardioplegia in Infants and Neonates in Congenital Heart Surgery.

BACKGROUND: The aim of this study was to evaluate outcome measures after the use of del Nido (dN) cardioplegia compared with conventional multidose high-potassium (non-dN) cardioplegia in neonates and infants. METHODS: We retrospectively analyzed data in patients, aged younger than 1 year, undergoing cardiopulmonary bypass (CPB) from January 2012 to August 2015. We changed our cardioplegia protocol from non-dN to dN administered in a single or infrequently dosed strategy in September 2013. The outcomes of the dN group (n = 107) are compared with the non-dN group (n = 118). We analyzed variables for demographic, intraoperative, early postoperative, and discharge variables. RESULTS: The two groups were similar in age, weight, height, CPB, and cross-clamp time; preoperative and postoperative echocardiographic systolic functions; first 24-hour postoperative urine output and inotropic score; length of stay; and mortality rate. The Society of Thoracic Surgeons/European Association for Cardio-Thoracic Surgery Congenital Heart Surgery (STAT) mortality category was significantly higher in the dN group (p = 0.03). The cardioplegia dosing interval was lower for the non-dN group (p < 0.001). The volume and doses of cardioplegia per patient were significantly higher in the non-dN group (p < 0.001). In a subanalysis, when the Norwood patients were excluded from both groups, the overall STAT mortality category difference was no longer significant. The demographic, early postoperative, and discharge variables still showed no significant difference when the two groups were compared. CONCLUSIONS: Similar outcomes can be achieved with less frequent interruption of the operation and lower volume of cardioplegia when using dN cardioplegia solution compared with conventional cardioplegia. The dN cardioplegia with extended ischemic interval can be used as an alternative strategy in the neonatal and infant population during cardiac operations.

Preparation of viable adult ventricular myocardial slices from large and small mammals.

This protocol describes the preparation of highly viable adult ventricular myocardial slices from the hearts of small and large mammals, including rodents, pigs, dogs and humans. Adult ventricular myocardial slices are 100- to 400-µm-thick slices of living myocardium that retain the native multicellularity, architecture and physiology of the heart. This protocol provides a list of the equipment and reagents required alongside a detailed description of the methodology for heart explantation, tissue preparation, slicing with a vibratome and handling of myocardial slices. Supplementary videos are included to visually demonstrate these steps. A number of critical steps are addressed that must be followed in order to prepare highly viable myocardial slices. These include identification of myocardial fiber direction and fiber alignment within the tissue block, careful temperature control, use of an excitation-contraction uncoupler, optimal vibratome settings and correct handling of myocardial slices. Many aspects of cardiac structure and function can be studied using myocardial slices in vitro. Typical results obtained with hearts from a small mammal (rat) and a large mammal (human) with heart failure are shown, demonstrating myocardial slice viability, maximum contractility, Ca2+ handling and structure. This protocol can be completed in ∼4 h.

Normokalemic nondepolarizing long-acting blood cardioplegia.

Objective Blood cardioplegia, the gold-standard cardioprotective strategy, requires frequent dosing, resulting in hyperkalemia-induced myocardial edema. The aim of our study was to compare the efficacy and safety of a long-acting blood-based cardioplegia with physiological potassium levels versus the well-established cold blood St. Thomas' Hospital no. 1 cardioplegia solution in multivalve surgeries. Methods One hundred patients undergoing simultaneous elective aortic and mitral valve replacement ± tricuspid valve repair were randomized in two groups. In group 1, adenosine 12 mg was given via the aortic root after crossclamping, followed by a single dose of long-acting solution at 14℃ (30 mLckg-1); in group 2, an initial 30 mLckg-1 of St. Thomas' cardioplegia at 14℃ was administered, followed by 15 mLckg-1 every 20 min. Duration of cardiopulmonary bypass, inotropic score, arrhythmias, ventilation time, and the levels of interleukin-6, creatinine kinase-MB, and troponin I were compared. Results Mean cardiopulmonary bypass and crossclamp times were 134.04 ± 36.12 vs. 154.34 ± 34.26 ( p = 0.004) and 110.37 ± 24.80 vs. 132.48 ± 31.68 min ( p = 0.002), respectively, in the long-acting and St. Thomas' groups. Cardiac index, creatinine kinase-MB and troponin I levels were comparable. Interleukin-6 levels post-bypass were 61.72 ± 15.33 and 75.44 ± 31.78 pgcmL-1 ( p = 0.007) in the long-acting and St. Thomas' cardioplegia groups, respectively. Conclusions Single-dose long-acting cardioplegia gives a cardioprotective effect comparable to repeated doses of the well-established St. Thomas' Hospital no. 1 cold blood cardioplegia.

Adding Emulsified Isoflurane to Cardioplegia Solution Produces Cardiac Protection in a Dog Cardiopulmonary Bypass Model.

This study investigated whether caridoplegia solution with Emulsified Isoflurane (EI) could improve cardiaoprotection in a dog CPB model of great similarity to clinical settings. Adult dogs were randomly assigned to receive one of the following cardioplegia solutions: St. Thomas with EI (group ST+EI), St. Thomas with 30% Intralipid (group ST+EL) and St. Thomas alone (group ST). The aorta was cross-clamped for two hours followed by reperfusion for another two hours, during which cardiac output was measured and dosages of positive inotropic agent to maintain normal hemodynamics were recorded. Serum level of cardiac troponin I (cTnI) and CK-MB were measured. Deletion of cardiac mitochondrial DNA was examined at the end of reperfusion. Compared with ST, ST+EI decreased the requirement of dopamine support while animals receiving ST+EI had a significantly larger cardiac output. ST+EI reduced post-CPB release of cTnI and CK-MB. Mitochondrial DNA loss was observed in only one of the tested animals from group ST+EI while it was seen in all the tested animals from group ST+EL and ST. Addition of emulsified isoflurane into cardioplegia solution protects against myocardial ischemia reperfusion injury. This protective effect might be mediated by preserving mitochondrial ultrastructure and DNA integrity.

Cardioplegic strategies for calcium control: low Ca(2+), high Mg(2+), citrate, or Na(+)/H(+) exchange inhibitor HOE-642.

BACKGROUND: Ca(2+) overload plays an important role in the pathogenesis of cardioplegic ischemia-reperfusion injury. The standard technique to control Ca(2+) overload has been to reduce Ca(2+) in the cardioplegic solution (CP). Recent reports suggest that Na(+)/H(+) exchange inhibitors can also prevent Ca(2+) overload. We compared 4 crystalloid CPs that might minimize Ca(2+) overload in comparison with standard Mg(2+)-containing CP: (1) low Ca(2+) CP (0.25 mmol/L), (2) citrate CP/normal Mg(2+) (1 mmol/L Mg(2+)), (3) citrate CP/high Mg(2+) (9 mmol/L Mg(2+)), and (4) the addition of the Na(+)/H(+) exchange inhibitor HOE-642 (Cariporide). We also tested the effect of citrate titration in vitro on the level of free Ca(2+) and Mg(2+) in CPs. METHODS AND RESULTS: Isolated working rat heart preparations were perfused with oxygenated Krebs-Henseleit buffer and subjected to 60 minutes of 37 degrees C arrest and reperfusion with CPs with different Ca(2+) concentrations. Cardiac performance, including aortic flow (AF), was measured before and after ischemia. Myocardial high-energy phosphates were measured after reperfusion. The in vitro addition of citrate to CP (2%, 21 mmol/L) produced parallel reductions in Mg(2+) and Ca(2+). Because only Ca(2+) was required to be low, the further addition of Mg(2+) increased free Mg(2+), but the highest level achieved was 9 mmol/L. Citrate CP significantly impaired postischemic function (AF 58.3+/-2. 5% without citrate versus 41.6+/-3% for citrate with normal Mg(2+), P:<0.05, versus 22.4+/-6.2% for citrate with high Mg(2+), P:<0.05). Low-Ca(2+) CP (0.25 mmol/L Ca(2+)) significantly improved the recovery of postischemic function in comparison with standard CP (1.0 mmol/L Ca(2+)) (AF 47.6+/-1.7% versus 58.3+/-2.5%, P:<0.05). The addition of HOE-642 (1 micromol/L) to CP significantly improved postischemia function (47.6+/-1.7% without HOE-642 versus 62.4+/-1. 7% with HOE-642, P:<0.05). Postischemia cardiac high-energy phosphate levels were unaffected by Ca(2+) manipulation. CONCLUSIONS: (1) A lowered Ca(2+) concentration in CP is beneficial in Mg(2+)-containing cardioplegia. (2) The use of citrate to chelate Ca(2+) is detrimental in the crystalloid-perfused isolated working rat heart, especially with high Mg(2+). (3) The mechanism of citrate action is complex, and its use limits precise simultaneous control of Ca(2+) and Mg(2+). (4) HOE-642 in CP is as efficacious in preservation of the ischemic myocardium as is the direct reduction in Ca(2+).

All-blood (miniplegia) versus dilute cardioplegia in experimental surgical revascularization of evolving infarction.

BACKGROUND: The advantages of blood cardioplegia include the oxygen-carrying capacity, superior oncotic and buffering properties, and endogenous antioxidants contained in blood. However, the partial dilution of blood in 4:1 (blood:crystalloid) cardioplegic solutions may nullify these advantages and progressively dilute blood during continuous retrograde delivery. This study tested the hypothesis that all-blood (66:1) cardioplegia provides superior myocardial protection compared with dilute (4:1) cardioplegia delivered in a continuous retrograde modality during surgical reperfusion of evolving myocardial infarction. METHODS AND RESULTS: After 60 minutes of left anterior descending coronary artery (LAD) occlusion, anesthetized canines were placed on cardiopulmonary bypass and randomized to either all-blood cardioplegia (AB group) or dilute blood cardioplegia (Dil group). After cross clamping, arrest was induced with 5 minutes of tepid (30 degrees C) antegrade potassium all-blood or dilute blood cardioplegia and maintained with tepid retrograde coronary sinus cardioplegia for a total of 1 hour. The LAD was released after 30 minutes of arrest, simulating revascularization. The cardioplegia hematocrit for the Dil group was lower than that for the AB group (7+/-1% versus 12+/-2%, P<0.05); at the end of bypass, systemic hematocrit was lower in the Dil group than in the Ab group (15+/-1% versus 20+/-1%, P<0.05). Infarct size (triphenyltetrazolium chloride staining) was comparable between the AB and Dil groups (29.6+/-2.9% versus 30.3+/-3.9% of area at risk), and there was no difference in area-at-risk myocardium systolic shortening (by sonomicrometry, -0.3+/-1% versus -0.4+/-1%). Tissue edema after bypass tended to be greater in the Dil group compared with the AB group in the heart (82+/-0% versus 81+/-1%), lung (79+/-1% versus 78+/-1%), liver (75+/-1% versus 74+/-0%), and skeletal muscle (76+/-1% versus 73+/-2%) and was significantly greater in the duodenum (80+/-1% versus 79+/-1%, P<0.05) and kidney (82+/-1% versus 79+/-1%, P<0.05). Postexperimental endothelial function (relaxation of acetylcholine) was impaired in LADs of the AB group versus the Dil group (59+/-6% versus 77+/-5%, P<0.05). CONCLUSIONS: Both all-blood cardioplegia and dilute cardioplegia have disadvantages, but these do not have an impact on the pathogenesis of infarct size or recovery of regional contractile function.

Eighteen-hour preservation of rat hearts with hexanol and pyruvate cardioplegia.

OBJECTIVES: The aim of this study was to evaluate the effectiveness of 1-hexanol as an arresting agent and pyruvate as a substrate in a cardioplegic solution. BACKGROUND: Heart transplantation is limited in part by the short preservation time of donor hearts. Better preservation techniques would improve patient survival and the time and geographic area for using donor hearts. We previously showed that a cardioplegic solution containing ethanol and pyruvate was superior to a conventional high potassium cardioplegic solution in 24-h cold storage of hamster hearts. Hexanol, a more potent arresting agent than ethanol, might be a more suitable alcohol. METHODS: Rat hearts were arrested and stored for 18 h at 4 degrees C with an ethanol (3 vol% = 510 mmol/liter) or 1-hexanol (4 mmol/liter) and pyruvate (10 mmol/liter) cardioplegic solution, St. Thomas' Hospital solution and Stanford solution and subsequently reperfused for 1 h at 35 degrees C. In other groups of hearts, basal oxygen consumption and rest intracellular calcium (Indo 1 technique) were evaluated during ethanol-, hexanol- and potassium-induced cardiac arrest. RESULTS: The percent recovery of left ventricular developed pressure and rate-pressure product were significantly better with the hexanol cardioplegic solution (67 +/- 21% and 58 +/- 19%, respectively; p < 0.05 for all comparisons) compared with the ethanol (10 +/- 7% and 5 +/- 4%), St. Thomas' Hospital (14 +/- 6% and 10 +/- 5%) and Stanford solutions (2 +/- 2% and 2 +/- 1%, respectively). Exclusion of ethanol and hexanol from storage solutions did not influence functional recovery. Values for oxygen consumption after 15- and 30-min ethanol- and hexanol-induced arrest were significantly lower than those after potassium-induced cardiac arrest. There was no difference in the rest intracellular calcium during cardiac arrest induced by the three arresting agents. CONCLUSIONS: A hexanol and pyruvate cardioplegic solution was more favorable than ethanol or conventional solutions for long-term cold storage of rat hearts. The beneficial effects of hexanol may have been provided in part by lower energy consumption during hexanol-induced cardiac arrest. These results may have implications for preservation of hearts for heart transplantation.

[Endothelium of myocardium microvessel under conditions of hypothermia, ischemia, reperfusion and pharmaco-cold cardioplegia with calcium antagonist].

Microvessels of the right atrium endothelium were investigated with electron microscope for patients with congenital heart disease receiving surgical treatment under deep perfusionless hypothermia and various methods of pharmaco-cold cardioplegia. In group 1, pharmaco-cold cardioplegia was performed, with hyperosmolar normopotash solution cooled down to 2-4 degrees C. In group 2, the same solution combined with isoptin, a potash-ion blocker, was applied. It has been shown that during global ischemia, stability of ion gradients on plasmalemma of endothelial cells is impaired, irrespective of the composition of cardioplegia solution. Alongside with this, ultrastructural reactions in group 1 proceed towards hyperosmia of endothelium accompanied by building up a large group of cells following coagulation necrosis. In group 2, by contrast, an intracellular edema progresses. The cardioprotective effect of isoptin, which is able to block Ca2+, manifests itself most vividly at reperfusion, when the blocking of cell potash overload prevents the development of dystrophic and destructive changes in endothelium of coronary microvessels, which present one of the most severe consequences in the process of blood flow recovery in ischemic tissues.

The protective potency of two commonly used cardioplegic solutions on cultured endothelial cells exposed to free-oxygen radicals injury.

Human umbilical vein endothelial cells were incubated with Bretschneider and St. Thomas II cardioplegic solution followed by a stimulation with cumene hydroperoxide (CHPO), which was used as an oxygen radicals generating agent. A statistically significant decrease of intracellular high energy phosphates (adenosine-5-trisphosphate: ATP; creatine phosphate: CP) compared to controls was observed in response to Bretschneider cardioplegia and CHPO. Furthermore, significant rises in prostaglandin I2 (prostacyclin; PGI2) production and lipidperoxidation were measured. The authors failed to record such alterations of endothelial cell metabolism for the St. Thomas II cardioplegic solution. They could also demonstrate that the cellular protection against oxygen radicals exerted by the St. Thomas II solution is attributable to procaine. The enhanced cytotoxicity of CHPO observed in presence of the Bretschneider solution was found to be partially caused by its constituent L-histidine, which led to significant decreases of high energy phosphates and increased lipidperoxidation when cells were subsequently treated with CHPO. However, alterations of high energy phosphate content initiated by CHPO and amplified by the Bretschneider solution could not be inhibited by adding procaine. Simultaneous pretreatment of cells with the Bretschneider solution and procaine and stimulation with CHPO resulted in decreases of ATP and CP, as observed using the Bretschneider cardioplegia alone.

Improved recovery of heart transplants with a specific kit of preservation solutions.

In the course of cardiac transplantation, donor hearts undergo a four-step sequence of events (arrest, cold storage, global ischemia during implantation, and reperfusion) during which myocardial damage can occur. We tested the hypothesis that the functional recovery of these hearts could be improved by exposure to two interdependently formulated preservation solutions throughout this four-step sequence. Solution I was used as a perfusion and storage medium during the first three steps, and solution II served as a modified reperfusate. The two solutions share the following principles of formulation: prevention of cell swelling (high concentrations of mannitol, a myocardium-specific impermeant) calcium overload (ionic manipulations), and oxidative damage (reduced glutathione) and enhancement of anaerobic energy production (glutamate). The two solutions differ with respect to the calcium content and buffering capacity. One hundred rat hearts perfused with isolated isovolumic buffer were subjected to cardioplegic arrest; cold (2 degrees C) storage for 5 hours, global ischemia at 15 degrees C for 1 hour, and normothermic reperfusion for 1 additional hour. In a first series of experiments (70 hearts), our kit of solutions was compared with six clinical preservation regimens that involved cardiac arrest with St. Thomas' Hospital or University of Wisconsin solutions followed by storage of the hearts in saline, Euro-Collins, St. Thomas' Hospital, or University of Wisconsin solutions. In a second series of experiments (30 hearts), the effects of the kit were more specifically investigated in relation to two types of additive--oncotic agents (dextran) and thiol-based antioxidants (reduced glutathione and N-acetyl-L-cysteine). According to comparisons of maximal rate of ventricular pressure increase and left ventricular compliance after reperfusion, the best myocardial protection was afforded by our kit of solutions. The addition of dextran during storage did not provide additional protection. Conversely, the omission of reduced glutathione was clearly detrimental; the replacement of reduced glutathione with N-acetyl-L-cysteine failed to improve recovery beyond that provided by antioxidant-free solutions, thereby suggesting the importance, in this model, of an anti-free radical compound that, like reduced glutathione, is operative extracellularly. We conclude that the preservation of heart transplants can be improved with the sequential use of two closely interrelated solutions, the formulations of which integrate the basic principles of organ preservation with those of myocardium-specific metabolism.