Newsletter home

Editor
Mark Twite, MA, MB, BChir, FRCP
E-MAIL

Co-Editor
Luis Zabala, MD
E-MAIL

INSIDE

President's Message

Letter from the Editor


Contrast Agents and Pediatric Cardiac Catheterization

LITERATURE REVIEW

Etomidate: The controversy continues

CCAS Meeting Reviews

Morning Sessions

Afternoon Sessions

 

 

 

Meeting Reviews

2014 CCAS Annual Meeting Scientific Program Summary

Morning Session

By Jeremy Geiduschek, MD & Gregory Latham, MD

The 2014 Spring Meeting of the CCAS in Ft. Lauderdale, Florida commenced with society president Dr. Helen Holtby greeting over 250 members and guests in the audience.  Dr. Wanda Miller-Hance assembled a fantastic line up of speakers for the day.

Session I: Basic Science & Practical Application

Dr. TaylorGregory Hammer, MD (Lucille Packard Children’s Hospital/Stanford University, Stanford CA) moderated the first session and introduced the lead off speaker, Doris Taylor, PhD (Texas Heart Institute, Houston TX). In her presentation we were all treated to a glimpse of the future and possibilities in alleviating the shortage of organs for transplantation. Dr. Taylor’s research focuses on the roles stem cells can play in organ injury repair and in creating a functional organ from decellularized organ skeletons.

Stem cell recruitment into injured organs is a key component of healing and repair. Stem cell number and function decrease with age, and males are affected at an earlier age. Inflammation is often a signal for stem cell migration, and delivery of the cells slows down inflammation. There are 528 trials listed on www.clinicaltrials.gov with keywords “stem cells” and “heart.” Studies are attempting to determine how to increase stem cell number, improve stem cell function, and increase stem cell survival in stressed environments (such as within an infarct). While some of these goals can be met, the flip side is development of uncontrolled proliferation and tumor generation, which is the bane of many studies.

Dr. Taylor reviewed the results of the Effectiveness of Stem Cell Treatment for Adults With Ischemic Cardiomyopathy Study (FOCUS-CCTRN). Patients with CHF who received intramyocardial injection of autologous bone marrow derived mesenchymal mononuclear stem cells, did not have an improvement in LVESV, maximal oxygen consumption, or reversibility on SPECT. A key learning was that as a baseline most of the subjects did not have stem cells with good function, with age being the largest determinant.

This has lead to three different strategies for subsequent study design:

  1. Selecting specific (potent) stem cells (e.g. autologous aldehyde dehydrogenase-bright stem cells),
  2. Alternative autologous sources (e.g. adipose-derived regenerative cells), and
  3. Using an allogeneic cell source (e.g. mesenchymal precursor cells from young donors). 

Studies using each of these strategies were described. Of note, one study revealed that the stem cells of one young donor did not appear to induce a clinically relevant immune response.

Dr. Taylor then addressed the potential of organogenesis to fulfill the unmet need for patients awaiting transplants and the growing numerical difference between those waitlisted every year and donor organ supply. The basic requirements to build an organ are cells (billions of them), scaffolding and physiology. Options for scaffold are collagen rings, bioprinting, or decellularized organ skeletons. Dr. Taylor’s research concentrates on the latter. The reader is referred to Dr. Taylor’s slides for amazing photos of organs that have undergone decellularization and the subsequent skeletons, including intact vascular walls, created in the process. Skeleton perfusion with stem cells can result in a functioning organ.

For an amazing look at a regenerated rat heart, see the YouTube video at: http://www.youtube.com/watch?v=j9hEFUpTVPA

Dr. Taylor concluded her presentation with a quote from Mahatma Gandhi:
“First they ignore you, then they laugh at you, then they fight you, then you win.”

Peter Laussen, MBBS (Hospital for Sick Children, Toronto ON) followed with a whirlwind presentation on “Heart Failure in Children: Current Management Strategies.” In his 40-minute presentation he covered subjects that often occupy hundreds of pages in textbooks. A brief overview by us — in children the most frequent causes of heart failure are cardiomyopathy, congenital heart disease, and acquired conditions (e.g. myocarditis). Variable mechanisms lead to combinations of myocyte structural abnormalities with deranged metabolism, mechanical, and/or conduction dysfunction. These in turn result in systolic and/or diastolic dysfunction of one or both ventricles. Differences between LV and RV failure were reviewed.

Depending on the etiology, the failing heart responds differently to volume load, pressure load, and endothelial chemistry modulation. Strategies for heart failure management vary depending on acuity and treatment goals. Traditional management is with inotropes (e.g. dobutamine, milrinone, vasopressin), which have associated negative consequences such as arrhythmias, impaired diastolic function, and aggravating ischemia/reperfusion injury. Newer approaches to management include medications that will modify how intracellular calcium is handled, activating myosin (e.g. Omecamtiv Mecarbil), activating endothelial NO synthase (Serelaxin), and determining alpha-2B and other signal polymorphisms to better direct medication selection and management.

When medical management is not succeeding then mechanical support remains an option. This can be ECMO and/or VAD. The complication rate with VAD is high. It is hoped that the upcoming Pumps for Kids, Infants, and Neonates (PumpKIN) Trial will provide direction on optimal mechanical support strategies to pursue. Dr. Laussen summarized that the major treatment goal is heart failure symptom relief and is usually initially with diuretics, afterload reduction, and if needed positive pressure ventilation. Inotropes should be used to treat shock, and ACE inhibitors and beta-blockers are added when the patient’s condition stabilizes. Consideration for mechanical support should occur before severe decompensation. For children with irrecoverable heart failure, early listing for heart transplantation is recommended.

A very brief Q & A session followed.  This year, audience members submitted questions anonymously on note cards. 

  1. Question to Dr. Taylor: What is the outlook for using stem cell regenerated heart valves and aortic arches for repairs?  Answer: For both there are numerous study protocols in various stages of completion.
  2. Question to Dr. Taylor: When decellularized skeletons are re-populated with stem cells, does overproliferation of cells occur?  Answer: Only about 20% of infused cells adhere and grow after delivery to the skeleton.  There have been no teratomas identified.
  3. Question to Dr. Laussen: Should we increase our emphasis on neonatal heart transplant for single ventricle patients?  Answer: Donor pool is too small to accommodate.  Listing should occur early.

Session II:  Practical Aspects of Cardiac Anesthesia Practice: A Potpourri

Suanne Daves, MD (Vanderbilt University Medical Center, Nashville TN) took to the podium to moderate this session on a variety of topics affecting the practice of many members of the audience.

Dr. DiazFirst was Laura Diaz, MD (Children’s Hospital of Philadelphia, Philadelphia PA) discussing a “Patient with a Berlin Heart Needs Non-Cardiac Surgery:  What Should I be Concerned With?” The Berlin Heart is a paracorporeal ventricular assist device that has four chamber sizes (10-80 mL) with a fifth expected on the market soon. Cardiomyopathy and myocarditis have been the leading indications for implantation, and it can be used for single or bi-ventricular support. The audience was directed to www.berlinheart.de for in-depth device information that is crucial to be familiar with when caring for patients with an implant.

Patients with a Berlin may undergo numerous types of procedures including: mediastinal exploration (50% bleeding rate), pump changes, cardiac caths, PICC placement, CT scans, tracheostomy, and bronchoscopy. Pre-anesthetic evaluation and the anesthetic management plan will be case specific. Some concerns include: anticoagulation (e.g. conversion to heparin then discontinuation within two hours of procedure), transfusion thresholds, staffing for transport, availability of VAD specialist, maintaining good RV output for patients with an LV implant (e.g. have NO available, milrinone, treat arrhythmias), adequacy of vascular access, concern for air entrainment from central lines (place antisiphon devices), indications for TEE, and how to maintain SVR and full volume status.

Dr. Diaz advocates that clear drapes be used in order to be able to visualize the drive lines and evaluate the filling and ejection of the pump (often with a mirror). Strategies for management of hypotension and circulatory arrest should be discussed with the team. Always evaluate the pump first. The pumps can be maintained with a hand crank in case of power failure. Patients with a Berlin can undergo chest compressions and defibrillation if necessary.

Larry Schwartz, MD (Children’s Hospital Colorado, Aurora CO) gave a presentation on “Dexmedetomidine: What is its Role in the Pediatric Cardiac Patient?” The pharmacology of dexmedetomidine (dex) and its many clinical effects were reviewed. These include: sedation with maintenance ventilation, sleep, bradycardia, hypo/hypertension, anxiolysis, anti-shivering, preservation of SSEP and MEP, and analgesia.

Though dex is not FDA approved for use in children there are numerous published studies describing its use in pediatric cardiac ICU sedation, during cardiac surgery, and in the cath lab. It has been considered “safe” in patients with pulmonary hypertension and it is advised NOT to use dex in patients undergoing cardiac electrophysiology procedures. Dex may play a role in protection against contrast-induced nephropathy. It is undergoing investigation as a possible mediator in organ protection in animals subject to sepsis or ischemia-reperfusion injury. Dex has also been shown in some studies to provide cortical neuroprotection against anesthetic induced neuroapoptosis in developing rat brains. Is dex a panacea? Probably not, but it is a useful tool in the care of children with CHD. 

Jane Heggie, MD (University of Toronto, Toronto ON) presented a case of a “Young Adult with Failed Fontan Circulation and Symptomatic Tachycardia: What is your Next Move?” There are currently more adults than children living with CHD. Adults with single ventricle Fontan circulation represent the extreme of the surviving CHD population. Most are survivors of single left ventricle physiology (DILV, TA, PA).

In the upcoming decade, more survivors of HLHS will be represented in this population. Many have undergone the classic RA to PA shunt. Most have considered themselves “cured” as children and may not present until they have developed heart failure and arrhythmias. Heart transplantation is often not an option for many adult CDH patients with heart failure. For those who do not have transplant exclusion criteria there is a severe lack of organ availability. Time on the wait list is longer due to competition with lung donation to acquire the increased length of donor vessels that are often needed for these patients.

There has been some work in converting from the classic Fontan to an extra-cardiac conduit and at the same time performing arrhythmia ablation therapy. Concerns for managing the adult Fontan patient for the anesthesiologist (and cardiologist) include lack of access to the atria or ventricles with a central line or temporary pacing catheter. Resuscitation mediations administered intravenously will have a longer transit time to effect sites due to the passage through the lungs.  Having the ability to transcutaneous pace is essential. Any cardioversion should be done only after ruling out atrial thrombus.

Q & A

  1. Question to Dr. Diaz:  Is there a database for anticoagulation management of patients with a Berlin Heart?  Answer: Not that she is aware of.
  2. Question to Dr. Heggie:  Who should care for the adult CHD patient?  Answer: Ideally there should be programatic support from the hospital to provide appropriate resources.  This should include collaboration between pediatric and adult specialists.
  3. Question to Dr. Diaz:  Do you do VAD changes in the OR or ICU?  Answer: In the OR with an anesthesiologist.
  4. Question to Dr. Schwartz: Can the use of dex make it difficult to monitor for occult blood loss due to masking of vital signs associated with hypovolemia?  Answer: This does not appear to be an issue in his practice.
  5. Question to Dr. Schwartz:  Have you encountered delayed awakening when combining dex with an opioid?  Answer: The dose of opiate is reduced when combing agents.

Session III:  Literature: Insightful Picks

Dean Andropoulos, MD, MHCM (Texas Children’s Hospital, Houston TX) introduced the next series of speakers, each of whom selected a recently published article that they considered important and relevant to pediatric cardiac anesthesiologists.

Andreas Loepke, MD, PhD (Cincinnati Children’s Hospital & Medical Center, Cincinnati OH) selected Krisch M, Sultan S, Sandell J et. al. Propofol anesthesia impairs the maturation and survival of adult-born hippocampal neurons. Anesthesiology 118:602-10, 2013.  “Adult-born” neurons result from continuous stem cell differentiation and occur across multiple species in the hippocampus and olfactory bulb. In this study, 8-10 week old mice were exposed to six hours of propofol at two different development time points (17 or 11 days after labeling of new adult-born neurons). The 17-day-old neuron has significantly greater impaired development compared to the 11-day-old group. This raises huge questions about anesthetic effects on neurologic development in neonates vs. adults, and both groups have vulnerable neurons.

Richard J Levy, MD (Children’s National Medical Center, Washington DC) chose Awad H, Ankeny D, Guan Z, et. al. A mouse model of ischemic spinal cord injury with delayed paralysis caused by aortic cross clamping. Anesthesiology 113:880-91, 2010. 

He started by asking the audience three questions:

  1. What is the typical duration of aortic cross clamp time for neonatal or infant coarctation of aorta repair at your institution?  4% were <10 min; 30% 10-15 min; 45% 15-20 min; and 20% >20 min.
  2. Do you use spinal cord protective measures during coarct repair?  52%-yes, 36%-no, 12%-sometimes.
  3. What measures are used?

Seventy percent active or passive hypothermia, 9% maximize BP or CSF drain, 9% monitor NIRS or SSEP, 11%-none. The study was an examination of varying combinations of aortic cross clamp time and body temperature in rats to determine a combination that consistently resulted in delayed (vs. immediate paralysis) hind leg neurologic impairment without mortality. This model will lead to more studies examining the mechanisms of subclinical pathologic conditions and perhaps pioneer protective measures.

Alexander Mittnacht, MD (Mount Sinai Medical Center, New York NY) selected Howard-Quijano K, Schwarzenberger J, Scovotti J, et. al. Increased red blood cell transfusions are associated with worsening outcomes in pediatric heart transplant patients. Anesthesia & Analgesia 116:1295-1308, 2013. This study met his criteria of being relevant, interesting, and a well-defined problem to study with sound statistical analysis. This was a single-institution retrospective study of 94 pediatric heart transplantations. Overall, 88% received a blood transfusion. Patients who had greater than 60 mL/kg transfused had a higher incidence of major adverse events including use of ECMO, dialysis and graft failure. Causality could not be proven, though analysis demonstrated that transfusion was an independent variable of ICU LOS and mean inotrope score.   

Back to top