Congenital Cardiac Anesthesia Society
A Section of the the Society for Pediatric Anesthesia

{“questions”:{“xv60e”:{“id”:”xv60e”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Authors: Dylan Trujillo, DO, Felipe Medeiros, MD, Destiny F. Chau, MD – Arkansas Children\u2019s Hospital \/University of Arkansas for Medical Sciences, Little Rock, AR \r\n\r\nTwo weeks following orthotopic heart transplantation for dilated cardiomyopathy, a 6-month-old male infant returns to the operating room for permanent pacemaker implantation. Which of the following is the MOST likely indication for permanent pacemaker implantation in this patient?\r\n\r\n”,”desc”:”EXPLANATION \r\nDysrhythmia following orthotopic heart transplantation (OHT) occurs in approximately 40% of pediatric recipients. Factors predisposing to dysrhythmia are multifactorial. One contributing factor relates to unopposed sympathetic tone secondary to donor heart denervation. Denervation leads to a lack of response to the modulating influence of the vagus nerve and to the higher baseline heart rate. Surgical techniques employed for orthotopic heart transplantation have also been implicated in the development of dysrhythmia. The biatrial technique preserves part of the recipient\u2019s right and left atrial tissue to facilitate the incorporation of the cardiac graft. The bicaval technique incorporates a cuff of the recipient\u2019s left atrial tissue. Scarring of the atria creates a predisposition to atrial flutter. In the biatrial method, P waves may be generated from both the cardiac graft and native atrial tissue which mimics atrial flutter. Additionally, sinus node activity from native atrial tissue may be conducted intermittently and thus manifest as ectopic atrial beats. As cuffs of atrial tissue are preserved in both techniques, all patients are expected to develop some degree of increased atrial size after OHT. Other factors which contribute to the risk of dysrhythmia after OHT include prolonged graft ischemic time, donor-recipient size mismatching (which contributes to atrial enlargement), acute and chronic rejection, and cardiac allograft vasculopathy. \r\n\r\nAtrial fibrillation and atrial flutter have been reported in 10% to 25% of patients after OHT with the majority of cases occurring in the first few weeks after transplantation and with eventual resolution in the majority of patients. Bradydysrhythmias occurring after OHT (which also frequently resolve spontaneously) include atrioventricular block and sinus bradycardia. Common causes include sinus node injury or ischemia, sympathetic denervation, and medication side effects. \r\nTemporary pacing for bradydysrhythmia is often utilized following OHT while the cardiac conduction system recovers from injury. Rarely, when normal cardiac conduction does not return, consideration of permanent pacemaker implantation is necessary. The 2021 PACES expert consensus on pediatric cardiovascular implantable electronic devices recommends waiting at least one week for spontaneous recovery of sinus node function. \r\nA systematic review of 11 studies by Mylonas et al. which included a total of 7,198 pediatric patients who underwent heart transplantation demonstrated that 1.9% of patients received a permanent pacemaker. However, although overall sinus node dysfunction was the most frequent indication for pacemaker placement (54.4% versus 45.6% for complete atrioventricular block), in almost half of the cases there was no indication reported. The need for pacemaker placement occurred earlier in the postoperative course in patients with complete atrioventricular block. The median time interval between OHT and permanent pacemaker implantation ranged from 17 days to 6.5 years in patients with complete heart block while it was 2.7 months to 12.5 years for sinus node dysfunction. The biatrial technique was utilized in 62.2% of patients and the bicaval technique in the remaining 37.8%. \r\n\r\nIn a single-center study by Mahmood et al., of 314 pediatric transplant recipients, 16 (5.1%) patients required permanent pacemaker placement. Indications for pacemaker placement were complete heart block in 75% of patients and sinus node dysfunction in 25% of patients. In 9 of 12 (75%) patients with complete heart block, the pacemaker was implanted within 21 days of the transplant. Three out of the four patients with sinus node dysfunction had pacemaker implantation at 61 days or longer after transplant. \r\nThe patient described in the question stem has undergone OHT two weeks prior without restoration of normal sinus rhythm and is most likely to have persistent complete atrioventricular block given the described time frame. Although symptomatic sinus bradycardia and second degree Mobitz Type II heart block can occur, they either resolve or persist to meet the indication for permanent pacemaker implantation at a later timepoint as compared to complete heartblock. At this early stage after OHT, close evaluation is important to rule out reversible causes of bradydysrhythmia such as acute rejection or antiarrhythmic medication side effects. \r\nREFERENCES \r\n\r\nNavas-Blanco JR, Modak RK. Perioperative care of heart transplant recipients undergoing non-cardiac surgery. Ann Card Anaesth<\/em>. 2021;24(2):141-148 doi: 10.4103\/aca.ACA_130_19. \r\n\r\n\r\nJoglar JA, Wan EY, Chung MK, et al. Management of arrhythmias after heart transplant: current\r\nstate and considerations for future research. Circ Arrhythm Electrophysiol <\/em>.2021;14(3):e007954. doi: 10.1161\/CIRCEP.120.007954. \r\n\r\nShah MJ, Silka MJ, Silva JNA, et al. 2021 PACES expert consensus statement on the indications and management of cardiovascular implantable electronic devices in pediatric patients. Cardiol Young<\/em>. 2021;31(11):1738-1769. doi:10.1017\/S1047951121003413\r\n\r\nMylonas KS, Repanas T, Athanasiadis DI, et al. Permanent pacemaker implantation in pediatric heart transplant recipients: A systematic review and evidence quality assessment. Pediatr Transplant<\/em>. 2020;24(3):e13698. doi: 10.1111\/petr.13698. \r\nMahmood A, Andrews R, Fenton M et al. Permanent pacemaker implantation after pediatric heart transplantation: Risk factors, indications, and outcomes. Clin Transplant <\/em>.2019;33(4) e13503. doi: 10.1111\/ctr.13503.\r\nHerrmann FEM, Wellmann P, Hagl C, Juchem G. Pediatric heart transplantation-What are the risk factors for pacemaker implantation and how much pacing is required? Pacing Clin Electrophysiol<\/em>. 2018;41(3):267-276. doi: 10.1111\/pace.13276.\r\n\r\n\r\n\r\n\r\n\r\n”,”hint”:””,”answers”:{“cl5cs”:{“id”:”cl5cs”,”image”:””,”imageId”:””,”title”:”A.\tComplete atrioventricular block “,”isCorrect”:”1″},”7mfo2″:{“id”:”7mfo2″,”image”:””,”imageId”:””,”title”:”B.\tSecond Degree (Mobitz) type II heart block”},”7278l”:{“id”:”7278l”,”image”:””,”imageId”:””,”title”:”C.\tSymptomatic sinus bradycardia “}}}}}

{“questions”:{“6ntww”:{“id”:”6ntww”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Authors: Dylan Trujillo, DO, Felipe Medeiros, MD, Destiny F. Chau, MD; Arkansas Children\u2019s Hospital\/University of Arkansas for Medical Sciences, Little Rock, AR \r\n\r\nAn 8-year-old male child with history of an orthotopic heart transplantation six years prior due to dilated cardiomyopathy presents for laparoscopic appendectomy. The patient is compliant with transplant medications and the last cardiac catheterization demonstrated normal hemodynamics without rejection. The vital signs are as follows: BP 97\/55, HR 108, SpO2 99% in room air, RR 21, and T 37.8^{o<\/sup>C. Laboratory results show: WBC 18 x 109 <\/sup>\/L, Hb 13 g\/dL, platelets 245 x 109 <\/sup>\/L. At present, which of the following is the MOST likely cause of morbidity and mortality in this patient?\r\n\r\n\r\n”,”desc”:”EXPLANATION \r\nThe primary causes of mortality following orthotopic heart transplantation (OHT) vary with the time elapsed since transplant. Common causes of death include acute rejection, infection, cardiac allograft vasculopathy (CAV) and malignancy. While acute rejection is the leading cause of death during the first 3 years following OHT, CAV predominates thereafter as the leading cause of mortality. \r\n\r\nAccording to data from the International Society of Heart and Lung Transplantation, approximately 20% of OHT recipients have some degree of CAV at 5 years and 25% at 10 years post-transplant. The mortality rate after CAV diagnosis is high across all age groups. There is 25% 2-year mortality in patients with any severity of CAV and 50% 2-year mortality in patients with moderate-to-severe CAV. Infants have the worst survival rates with a median of 2 years after CAV diagnosis. The clinical symptom of chest pain from myocardial ischemia is typically absent due to denervation of the transplanted heart. Therefore, severe CAV manifests as progressive deterioration in graft function, heart failure, or sudden death. For this reason, transplant recipients are usually screened on a yearly basis for CAV using coronary angiography or dobutamine stress echocardiography. The histologic appearance of CAV is that of concentric intimal and medial proliferation that ultimately results in luminal occlusion, diastolic dysfunction, and graft failure. Treatment of CAV includes percutaneous revascularization procedures such as balloon angioplasty and coronary artery stenting, but the success rate is low due to the diffuse nature of the disease. Cardiac re-transplantation should be considered for those patients with moderate to severe CAV and graft dysfunction. \r\n\r\nThe rate of infection in OHT patients is highest in the first year after transplantation, accounting for approximately 16% of deaths, but declines thereafter. As immunosuppressive therapy can potentiate the severity of infections, early diagnosis and aggressive therapy of infection is imperative. In a 2006 single institution, retrospective review by Savar et al. of 8000 solid organ transplants (which included four OHTs and one heart-kidney transplant), 17 patients underwent appendectomy with an average age of 37 years (range 6yrs-73yrs). They reported no deaths, no episodes of acute organ rejection, and no intraoperative complications after appendectomy. \r\n\r\nAcute rejection is the most frequent cause of death during the first year after OHT. Greater age at the time of transplantation increases the risk for acute rejection and is associated with lower survival. The risk of malignancy increases over time, with an incidence of approximately 10% at 10 years and 16% at 15 years post-transplant. Although post-transplant lymphoproliferative disorders account for the vast majority of malignancies and are associated with reduced survival, they are not one of the leading causes of mortality after OHT. \r\n\r\nThe patient\u2019s cardiac status appears to be optimized given compliance with medications, normal cardiac catheterization data and negative biopsy results. As immunosuppression can exacerbate acute appendicitis, prompt treatment is imperative with good outcomes having been reported after surgical management. Perioperative continuation of the anti-rejection therapy is important for recovery. Obtaining a preoperative echocardiogram would be helpful to confirm cardiac function but should not delay surgery. As six years have elapsed since OHT, this patient\u2019s risk for acute rejection and malignancy is lower than for CAV; thus, CAV would be the most likely cause of morbidity and mortality in this patient. \r\n\r\n\r\nREFERENCES \r\nDipchand AI, Laks JA. Pediatric heart transplantation: long-term outcomes. Indian J Thorac Cardiovasc Surg.<\/em>2020; 36(Suppl 2):175-189. \r\n\r\nRossano JW, Dipchand AI, Edwards LB, et al. The Registry of the International Society for Heart and Lung Transplantation: Nineteenth pediatric heart transplantation report-2016; Focus theme: Primary diagnostic indications for transplant. J Heart Lung Transplant. <\/em>2016; 35(10):1185-1195. \r\n\r\nDipchand AI. Current state of pediatric cardiac transplantation. Ann Cardiothorac Surg. <\/em>2018; 7(1):31-55. \r\n\r\nSavar A, Hiatt JR, Busuttil RW. Acute appendicitis after solid organ transplantation. Clin Transplant. <\/em>2006; 20(1):78-80.\r\n\r\n”,”hint”:””,”answers”:{“7b5nr”:{“id”:”7b5nr”,”image”:””,”imageId”:””,”title”:”A.\tAcute graft rejection”},”hrz7u”:{“id”:”hrz7u”,”image”:””,”imageId”:””,”title”:”B.\tCardiac allograft vasculopathy”,”isCorrect”:”1″},”jlc2f”:{“id”:”jlc2f”,”image”:””,”imageId”:””,”title”:”C.\tMalignancy”}}}}}}

{“questions”:{“nvky1”:{“id”:”nvky1″,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Authors: Christopher Busack MD, Chinwe Unegbu MD, and Daniela Perez-Velasco DO \u2013 Children\u2019s National Hospital \r\n\r\nA 6-month-old male with Hypoplastic Left Heart Syndrome (HLHS) s\/p Norwood\/Sano modification receives an ABO-incompatible heart transplant secondary to severe tricuspid regurgitation and right ventricular dysfunction. After separation from cardiopulmonary bypass, the patient received 10 mL\/kg each of platelets, cryoprecipitate, fresh frozen plasma, and packed red blood cells. Which of the administered blood products carries the HIGHEST RISK of transmitting viral pathogens?\r\n\r\n”,”desc”:”EXPLANATION \r\n\r\nTransfusion of blood products has significant risks and benefits which must be carefully balanced. A recent publication by Faraoni et al. provides evidence-based guidelines for the use of blood products in the perioperative period for children undergoing cardiac surgery. \r\nIn the US, to facilitate more targeted transfusion of deficient blood components, whole blood is typically separated into various components. Fresh frozen plasma (FFP) is frozen within 8 hours of collection. Cryoprecipitate, also known as antihemophilic factor, is then prepared from FFP in the following manner. FFP is slowly thawed to 1-6 ^{o <\/sup>C followed by centrifugation. High-molecular-weight plasma proteins form a precipitate during centrifugation known as cryoprecipitate, which is then is collected, resuspended in a small amount of plasma (10-15 mL) and refrozen. Cryoprecipitate has several important coagulation proteins including fibrinogen, antihemophilic factor (factor VIII), von Willebrand factor, fibrin stabilizing factor (factor XIII), fibronectin, and small amounts of other plasma proteins. Cryoprecipitate has higher concentrations of coagulation proteins due to the smaller volume; making this blood product more appropriate for smaller patients in need of an increased concentration of the aforementioned coagulation proteins. Cryoprecipitate doses of 1-2 units per 10 kg of body weight will increase fibrinogen concentration by 60 to 100 mg\/dL. \r\nIn the 1960\u2019s, cryoprecipitate was used to manage patients with Hemophilia A. The initial preparations of cryoprecipitate had relatively low Factor VIII concentrations. Therefore, Hemophilia A patients required transfusion of multiple bags of cryoprecipitate to achieve an adequate dose of 20-30 IU\/kg. Additionally, cryoprecipitate was pooled from large amounts of plasma obtained from multiple donors. Unfortunately, these specimens were often contaminated with hepatitis viruses. It is estimated that in the 1980\u2019s, HIV was transmitted to 50% of people living with Hemophilia A. In current medical practice, cryoprecipitate is used to correct fibrinogen deficiency due to acute blood loss (secondary to trauma, surgery, etc) or qualitative abnormalities of the fibrinogen protein. Currently, there are no widely available commercial methods of inactivating viral pathogens in FFP or cryoprecipitate. As cryoprecipitate is a pooled product, its administration carries the highest risk of the transmission of viral pathogens (Munlemvo et al). Many Western European countries and Canada have banned the use of cryoprecipitate due to concerns about pathogen transmission. Cryoprecipitate is no longer recommended to treat von Willebrand\u2019s Disease or Hemophilia A unless recombinant or viral inactivated products are not available. The availability of highly purified coagulation factor concentrates and recombinant protein preparations has superseded the use of cryoprecipitate for many coagulopathies. \r\nIn contrast, platelets are associated with the highest risk of bacterial contamination due to the need for storage at room temperature. Transfusion transmitted infections, although rare, can have serious consequences. Nucleic acid testing (NAT) has increased the sensitivity of detecting infectious agents in donor blood. This form of testing directly tests the donated blood for viruses, whereas previous screening was done by testing antibody response to viral infection. NAT has reduced the risk of infectious transmission to less than 1 in 1,000,000. Donor blood is now screened for many viruses and bacteria such as the following: HIV, hepatitis B, hepatitis C, HTLV, syphilis, West Nile virus, Chagas disease, Zika virus, and babesiosis. Leukoreduction of blood products is also used to decrease the risk of CMV transmission, which can be fatal in newborns and immunocompromised patients. \r\nTransfusion of blood products carries additional risks occurring with greater frequency than infectious transmission. Recent investigations suggest that blood product transfusion during pediatric cardiac surgery may be associated with adverse outcomes such as renal failure, low cardiac output, vascular thrombosis, and alloimmunization leading to increased time to orthotopic transplantation, prolonged hospital stay, and increased mortality. Guidelines have shifted away from recommending specific hemoglobin targets and instead weighing the risk of complications from blood product transfusion versus the risk of complications from inadequate oxygen-carrying capacity, inadequate hemostasis, and\/or inadequate intravascular volume. \r\nREFERENCES \r\n\r\n1. Faraoni D, Meier J, New HV, Van der Linden PJ, Hunt BJ. Patient Blood Management for Neonates and Children Undergoing Cardiac Surgery: 2019 NATA Guidelines. J Thorac Cardiovasc Anesth.<\/em> 2019; 33:3249-3263. https:\/\/doi.org\/10.1053\/j.jvca.2019.03.036 \r\n\r\n2. Munlemvo DM, Tobias JD, Chenault KM, Naguib A. Prothrombin Complex Concentrates to Treat Coagulation Disturbances: An Overview with a Focus on Use in Infants and Children. Cardiol Res.<\/em> 2022;13(1):18-26. doi:10.14740\/cr1342 \r\n\r\n3. Steinbicker AU, Wittenmeier E, Goobie SM. Pediatric non-red cell blood product transfusion practices: what\u2019s the evidence to guide transfusion of the \u201cyellow\u201d blood products? Curr Opin Anesthesiol. <\/em>2020;33(2):259-267. doi:10.1097\/ACO.0000000000000838 \r\n\r\n4. Busch MP, Bloch EM, Kleinman S. Prevention of transfusion-transmitted infections. Blood.<\/em> 2019;133(17):1854-1864. doi:10.1182\/blood-2018-11-833996 \r\n\r\n5. Sparrow RL, Simpson RJ, Greening DW. Preparation of Cryoprecipitate and Cryo-depleted Plasma for Proteomic Research Analysis. Methods Mol Biol.<\/em> 2023;2628:41-49. doi:10.1007\/978-1-0716-2978-9_\r\n”,”hint”:””,”answers”:{“68u32”:{“id”:”68u32″,”image”:””,”imageId”:””,”title”:”A. Platelets”},”p4irc”:{“id”:”p4irc”,”image”:””,”imageId”:””,”title”:”B. Cryoprecipitate”,”isCorrect”:”1″},”zah5m”:{“id”:”zah5m”,”image”:””,”imageId”:””,”title”:”C. Fresh Frozen Plasma (FFP)”},”5ajdc”:{“id”:”5ajdc”,”image”:””,”imageId”:””,”title”:”D. Packed Red Blood Cells (PRBC)”}}}}}}

{“questions”:{“i1s4t”:{“id”:”i1s4t”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Authors: Christopher Busack MD, Chinwe Unegbu MD, and Daniela Perez-Velasco DO \u2013 Children\u2019s National Hospital \r\nA 3-month-old female patient presents with failure to thrive. Echocardiography reveals severe LV dysfunction, severe mitral regurgitation, and an anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA).Which operative intervention MOST LIKELY reduces the risk of in-hospital death in patients undergoing surgical repair of ALCAPA?\r\n\r\n\r\n”,”desc”:”EXPLANATION \r\nAnomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) comprises less than 1% of congenital heart defects. There are two clinical phenotypes: (1) infants with an absence of adequate collateral circulation from the right coronary artery (RCA) to the left side of the heart who typically present with severe heart failure symptoms within the first few months of life and (2) patients with adequate collateral supply who remain asymptomatic until adolescence or adulthood. However, patients with collateral supply remain at risk for sudden cardiac death and may present with chest pain or dyspnea on exertion. Without surgical intervention, the mortality exceeds 90% at this time. However, with surgery and current advances, the mortality at the time of ALCAPA repair is less than 10%. Echocardiography is the mainstay of diagnosis but CT angiography or magnetic resonance imaging with 3D reconstruction can be helpful. Angiography is rarely indicated except in special situations. \r\n\r\nAlthough mitral regurgitation (MR) is commonly associated with ALCAPA, there is no consensus as to whether it should be surgically corrected at the time of primary repair. Obviously, correction would add ischemia time to an already severely compromised ventricle. In most cases, MR improves without intervention after surgery to correct ALCAPA alone due to improved ventricular function and reduced end-diastolic volume. However, MR persists in some cases and may require intervention later. Several recent studies indicate that repair of severe MR at the time of initial surgery can be achieved with low risk, improved outcomes, and a reduced need for reoperation. These data support a selective surgical approach for significant MR at the time of ALCAPA surgery, perhaps focusing on cases with structural defects unlikely to change with improvement in myocardial function or regression of ventricular dilation. Neither prophylactic ventricular assist device insertion nor pulmonary arterioplasty at the time of ALCAPA repair reduce the risk of in-hospital death. \r\nREFERENCES \r\n\r\n1.\tThomas AS, Chan A, Alsoufi B, Vinocur JM, Kochilas L. Long-term Outcomes of Children Operated on for Anomalous Left Coronary Artery From the Pulmonary Artery. Ann Thorac Surg. <\/em>2022;113(4):1223-1230. doi: 10.1016\/j.athoracsur.2021.07.053. \r\n\r\n2.\tYu J, Ren Q, Liu X, et al. Anomalous left coronary artery from the pulmonary artery: Outcomes and management of mitral valve. Front Cardiovasc Med. <\/em>2022;9:953420. doi: 10.3389\/fcvm.2022.953420. \r\n\r\n3.\tWeixler VHM, Zurakowski D, Baird CW, et al. Do patients with anomalous origin of the left coronary artery benefit from an early repair of the mitral valve? Eur J Cardiothorac Surg.<\/em> 2020;57(1):72-77. doi: 10.1093\/ejcts\/ezz158.\r\n\r\n”,”hint”:””,”answers”:{“25awu”:{“id”:”25awu”,”image”:””,”imageId”:””,”title”:”A. Prophylactic ventricular assist device insertion at time of ALCAPA repair”},”kkhq0″:{“id”:”kkhq0″,”image”:””,”imageId”:””,”title”:”B. Concomitant mitral valve surgery at time of ALCAPA repair”,”isCorrect”:”1″},”v9zmu”:{“id”:”v9zmu”,”image”:””,”imageId”:””,”title”:”C. Pulmonary arterioplasty at the time of ALCAPA repair”}}}}}

{“questions”:{“ixofz”:{“id”:”ixofz”,”mediaType”:”image”,”answerType”:”text”,”imageCredit”:””,”image”:””,”imageId”:””,”video”:””,”imagePlaceholder”:””,”imagePlaceholderId”:””,”title”:”Authors: Christopher Busack MD, Chinwe Unegbu MD, and Daniela Perez-Velasco DO \u2013 Children\u2019s National Hospital \r\n\r\nA 4-year-old male patient with an atrial septal defect presents for surgical repair with cardiopulmonary bypass. The surgeon plans on using a clear pump prime with a hyperpolarized cardioplegic arrest. Which cardioplegia solution produces a hyperpolarized cardiac arrest?\r\n\r\n “,”desc”:”EXPLANATION \r\nThe ability to induce cardiac arrest and facilitate open-heart surgery by infusing a high potassium-containing solution into the coronaries was first demonstrated by Melrose et al. in 1955 in a canine experimental model. Different cardioplegia solutions today consist of varying amounts of electrolytes (potassium, sodium, calcium and magnesium), buffers and medications. Cardioplegia is administered after cross clamp of the aorta either in an antegrade fashion via the coronary arteries or retrograde via the coronary sinus. Cardioplegic solutions cause diastolic arrest, decrease cardiac metabolic demand, and improve myocardial tolerance to ischemia. \r\n\r\nThe most common method for achieving cardiac arrest is by providing a high concentration of potassium (K^{+ <\/sup>) ions into the extracellular space. Extracellular cardioplegic solutions often contain high concentrations of sodium (Na+ <\/sup>), calcium (Ca2+ <\/sup>), potassium (K+ <\/sup>), magnesium (Mg2+ <\/sup>), and bicarbonate and cause cardiac arrest by depolarizing the myocardial membrane. The Buckberg and St. Thomas\u2019 Hospital cardioplegia solutions both contain high K+ <\/sup>content and are delivered with blood. A major drawback with both of these solutions is that they require frequent re-dosing. \r\n\r\nA concern with depolarizing arrest is Ca2+ <\/sup> accumulation in the myocytes, thereby preventing myocardial relaxation. To mitigate this effect, contemporary depolarizing cardioplegia solutions contain lidocaine and magnesium. These agents repolarize the cell membrane to some degree and prevent Na+ <\/sup> and Ca2+ <\/sup> accumulation within the cell. Del Nido cardioplegia includes lidocaine and magnesium and is categorized as a modified extracellular depolarizing solution. A 2016 retrospective review by Buel et al. demonstrated a six-fold decrease in the rate of defibrillation post cross-clamp with del Nido cardioplegia compared to the St. Thomas Hospital solution. The del Nido cardioplegia solution was developed for pediatric cardiac surgery due to the specific needs of an immature and developing myocardium. The immature myocardium has a higher sensitivity to intracellular Ca2+ <\/sup> since the sarcoplasmic reticulum is underdeveloped with a reduced capacity to store Ca2+ <\/sup>. Studies in adults have also shown benefit of the del Nido solution and it is used in many adult centers. \r\n\r\nIntracellular cardioplegia solutions have low levels of Na+ <\/sup>and Ca2+ <\/sup> mimicking the intracellular electrolyte concentration. These solutions induce a hyperpolarizing arrest of the myocardium which decreases energy consumption and intracellular accumulation of Ca2+ <\/sup>. Histidine\u2013tryptophan\u2013ketoglutarate (HTK) solution (Custodiol HTK\u00ae\/Bretschneider solution) is an intracellular cardioplegic solution that was introduced in the 1970s. Histidine buffers ischemia-induced acidosis; tryptophan is an effective cell membrane stabilizer; ketoglutarate enhances energy production and recovery following reperfusion; and mannitol minimizes cellular edema by maintaining the osmolality of the cellular environment and functions as a free radical scavenger. HTK solution is particularly useful for long complex repairs as it reliably produces cardiac arrest for up to 120 minutes without redosing.\r\n\r\nThere is no consensus regarding the \u201cbest\u201d cardioplegia solution. Numerous studies have demonstrated that multiple cardioplegia options safely achieve myocardial protection. However, a recent 2018 study by Panigrahi et al suggests that the del Nido solution may offer some additional benefits including quicker resumption of normal cardiac rhythm and decreased inotropic support compared to conventional blood cardioplegia. A 2019 randomized controlled trial by Talwar et al. compared HTK solution and del Nido solution. The del Nido group demonstrated a better cardiac index, less mechanical ventilation days, and shorter ICU stays. Electron microscopy also showed less edema of the myocardium and better myofibrillar architecture with del Nido solution. The higher cellular edema seen with the HTK solution may be related to its very low sodium content. Nonetheless, there is more research to be done in this area.\r\n\r\n\r\n \r\nREFERENCES \r\n1.\tMelrose DG, Dreyer B, Bentall HH, Baker JB. Elective cardiac arrest. Lancet <\/em>. 1955;269(6879):21-2. doi: 10.1016\/s0140-6736(55)93381-x \r\n\r\n2.\tTalwar S, Chatterjee S, Sreenivas V, et al. Comparison of del Nido and histidine-tryptophan-ketoglutarate cardioplegia solutions in pediatric patients undergoing open heart surgery: A prospective randomized clinical trial. J Thorac Cardiovasc Surg <\/em>. 2019;157(3):1182-1192.e1. doi: 10.1016\/j.jtcvs.2018.09.140 \r\n\r\n3.\tWatanabe M, Egi K, Shimizu M, et al. Non-depolarizing cardioplegia activates Ca2+-ATPase in sarcoplasmic reticulum after reperfusion. Eur J Cardiothorac Surg<\/em>. 2002;22(6):951-6. doi: 10.1016\/s1010-7940(02)00582-1. \r\n\r\n4.\tPanigrahi D, Roychowdhury S, Guhabiswas R, Rupert E, Das M, Narayan P. Myocardial protection following del Nido cardioplegia in pediatric cardiac surgery. Asian Cardiovasc Thorac Ann<\/em> 2018;26(4):267-272. doi: 10.1177\/0218492318773589 \r\n\r\n5.\tBibevski S, Mendoza L, Ruzmetov M, et al. Custodiol cardioplegia solution compared to cold blood cardioplegia in pediatric cardiac surgery: a single-institution experience. Perfusion <\/em>.2020;35(4):316-322. doi: 10.1177\/0267659119878006 \r\n\r\n6.\tMatte GS, del Nido PJ. History and use of del Nido cardioplegia solution at Boston Children’s Hospital [published correction appears in J Extra Corpor Technol. 2013;45(4):262]. J Extra Corpor Technol <\/em>. 2012;44(3):98-103.\r\n\r\n7.\tDamiano RJ Jr, Cohen NM. Hyperpolarized arrest attenuates myocardial stunning following global surgical ischemia: an alternative to traditional hyperkalemic cardioplegia? J Card Surg <\/em>. 1994;9(3 Suppl):517-25. doi: 10.1111\/jocs.1994.9.3s.517 \r\n\r\n8.\tGiordano R, Arcieri L, Cantinotti M, et al. Custodiol Solution and Cold Blood Cardioplegia in Arterial Switch Operation: Retrospective Analysis in a Single Center. Thorac Cardiovasc Surg<\/em>. 2016;64(1):53-8. doi: 10.1055\/s-0035-1566235 \r\n\r\n9.\tGhiragosian C, Harpa M, Stoica A, et al. Theoretical and Practical Aspects in the Use of Bretschneider Cardioplegia. J Cardiovasc Dev Dis<\/em>. 2022;9(6):178. doi: 10.3390\/jcdd9060178 \r\n\r\n10.\tTurkoz R. Myocardial protection in pediatric cardiac surgery. Artif Organs<\/em>. 2013;37(1):16-20. doi: 10.1111\/aor.12029\r\n\r\n”,”hint”:””,”answers”:{“dn2p6”:{“id”:”dn2p6″,”image”:””,”imageId”:””,”title”:”A. Buckberg solution”},”ozwpt”:{“id”:”ozwpt”,”image”:””,”imageId”:””,”title”:”B. St. Thomas solution”},”m090t”:{“id”:”m090t”,”image”:””,”imageId”:””,”title”:”C. Histidine\u2013tryptophan\u2013ketoglutarate (HTK) solution”,”isCorrect”:”1″},”3fcsw”:{“id”:”3fcsw”,”image”:””,”imageId”:””,”title”:”D. del Nido solution\r\n\r\n”}}}}}}