Myocardial Protection in Pediatric Cardiac Surgery


Published on

Myocardial Protection in Pediatric Cardiac Surgery

Published in: Health & Medicine
  • Be the first to comment

No Downloads
Total Views
On Slideshare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide
  • ( SLAYD)
  • The first cardioplegic arrest was used by Melrose in 1955 However the high () of the K is not acceptable today due to its toxicity. In the following 20 years, the mortality rate of cardiac surgery had been between 10-20 %. During these years, the myocardial protection method consisted of ( SLAYD) ……………
  • The first succesful Pharmacological arrest was used by Bretschneider in 1964 . This was the initial form of todays HTK solution. St Thomas solution was introduced in 1975, and has become the most used cristaliod C world wide. Modern blood C was iniatially introduced by Buckberd in 1978
  • Why is MP important.? First; ( SLAYD) ………………….. On the other hand, with the current myocardial protection techniques, this duration is prolonged up to 4-5 hours without causing any myocardial damage.
  • There are many differences between pediatric and adult hearts. Morphologically ( SLAYD) …………………
  • Clinical differences between pediatric/adult myocardium Experimentally , ( SLAYD) …………. Ho wever, ( SLAYD) ……….. ( SLAYD)
  • Physiologically immature Myocardium has ( SLAYD) ……………
  • The sarcoplasmic reticulum is underdeveloped in the pediatric heart and has a reduced storage capacity for calcium The activity of the sarcoplasmic CaATPase is lower than in the adult heart
  • This slide shows a schematic drawing of myocardial energy substrate metabolism. In adult myocardium, up to 90% of ATP production is derived from the oxidation of fatty acids. In contrast, the main substrate for the neonatal heart is glucose.
  • The two contemporary myocardial protection methods used in pediatric cardiac surgery are… ( SLAYD)
  • The advantages of cardioplegia are …………( SLAYD)
  • In heart transplantation in the US. It has been reported that 167 different cardioplegic solusions have been used. Therefore it is not suprising to have more variety of cardioplegic solutions in pediatric cardiac surgery
  • The main component of C is potasium. Low Ca level is preferred to prevent Ca padox and reperpfusion injury . Mg is also added in C solusion to prevent Ca induced myocardial injury . Baykarbonate and THAM are used for buffering Aspartate and glutamate , which take part in crebs cycle, are used in cardioplegia in some clinics. Glucose is used as an energy source in cardioplegia. Many other substrates including …… ( SLAYD) ………. have been used in experimental studies. However most of them were not used in clinical practice.
  • Cristaloid and Blood C are both widely used in clinical practice. Crystalloid C have some advantages such as …… ( SLAYD) ………… On the other hand, The adventages of Blood C are more physiological and has oxygen free radical scavenger s and also the Blood C is superior to cristalloid C over 1 h ischemia
  • Hypothermia has been used since 1950 for myocardial protection as a cornerstone The methods to cool the heart are Cold cardioplegia Systemic cooling Topical myocardial cooling which has a disadventage of phrenic nerve damage The arrested, normothermic heart requires 90%less oxygen than does the norm othermic working heart
  • This is an interesting grafic which showes that there isn’t much difference in terms of O2 consumption in the arrested heart between normothermia and hypothermia. The black bars show there isn’t much difference between 37 C and 22 C in arrested hearts.
  • Hypothermia appears to have several detrimental effects, such as impaired mitochondril and sarcoplasmic reticulum function. These effects lead to a depletion of myocardial energy supplies In 1989, Lichtenstein was the first to use normothermic continuous blood cardioplegia in a patient with complicated MVR. The patient had a posterior wall rupture and repair was succesfully performed with over 6 h of safe CC times .
  • Today, warm and cold blood cardioplegia are used combined in modern methods. In this technique, warm induction and then cold induction after CC. During the CC cold blood C is given every 15-20 min. The terminal warm blood cardioplegia is given as a hot shot before removing the aortic CC
  • Ant , redr and combined methods are used in cardioplegia delivery Antegrade delivery is simple and the cardioplegia is equally distributed to the coronary arteries. The disadvantage is a risk of poor antergrade perfusion in AI and possible injury to the coronary ostia in open aorta.
  • Retrograde delivery has Nonphysiological, Nonhomogenous distribution. It is advantageous in AI and aortic root surgery
  • Cardioplegia is used in single or multi doses Multi-dose cold cardioplegia is usualy given every 20-30 min However, Multi-dose warm cardioplegia is usualy given in shorter intervals
  • Ventricular hypertrophy is a risk factor for adequate MP. Preischemic conditining including cardiogenic shock or LCO state is also a risk factor for MP. Ventricular distention , Retraction and Ventriculotomy may lead to myocardial injury. Reperfution injury after the CC is a high risk in cyanotic heart . CPB should be instituted with a Po2 of no greater than 200 mm Hg to prevent oxidant-mediated reoxygenation injury Coronary artery injury and embolism of air to coronary are also a risk factor for adequate MP.
  • Many factors may lead to postoperative LCO related to volume and pressure oveloads, hypovolemia, tamponat and rythym changes.
  • In our clinical practice we prefer miniplegia with anterograde delivery. In Extracardiac operations such as BDCPS and Ext Fontan and right side operation we operat on CPB without aortic CC
  • This is our minicardioplegia system. The cardioplegia composition is infused with an infusion pump into the oxygenated blood that is delivered from the roller pump.
  • Our miniplegia solution includes 30 ml K, 10 ml Mg and 20 ml Dextrose. Induction K [ ] is 25 meq per lıter Maintanance K [ ] is 13 meq per liter
  • This is the Cardioplegia protocol corrected for patient weight
  • ( SLAYD)
  • Myocardial protection is challenging in some cases FOR EXAMPALE ( SLAYD) …………………….
  • ( SLAYD) …
  • Myocardial Protection in Pediatric Cardiac Surgery

    1. 1. Myocardial Protection in Pediatric Cardiac Surgery
    2. 2. No Disclosures
    3. 3. High KHigh K++ cardiac arrest Melrose 1955 –Potassium citrate ( 77m mol/L) ~~20 years(Mortality20 years(Mortality ~~10-20%)10-20%) Hypothermia: systemic and/or topicalHypothermia: systemic and/or topical  Bigelow et al. 1950; Shumway et al. 1959; Swan 1973 Continuous or intermittent aortic occlusion  Cooley et al. 1962 Aortic root or intracoronary blood perfusion  Kay et al. 1958 Ellectrically induced VF (fibrilator)Ellectrically induced VF (fibrilator)  Senning 1952 HistoryHistory
    4. 4. Pharmacological arrest was firstPharmacological arrest was first successfully used bysuccessfully used by Bretschneider* in 1964 (HTK)Bretschneider* in 1964 (HTK) St. Thomas in 1975St. Thomas in 1975 Blood cardioplegiaBlood cardioplegia Buckberg et al, in 1978Buckberg et al, in 1978 HistoryHistory *Bretschneider HJ (1964) U˝ berlebenszeit und Wiederbelebungszeit des Herzens bei Normo undHypothermie. Verh Deutsch Ges Kreislaufforschung 30: 11 34.
    5. 5. Importance of MP 1.1. IIrreversible ischemic damagerreversible ischemic damage begins tobegins to occur in theoccur in the normothermicnormothermic heart after only 20 minheart after only 20 min 2.2. However,However, when current techniqueswhen current techniques of myocardial protection are used,of myocardial protection are used, arrest times of more than 4 or 5arrest times of more than 4 or 5 hours may behours may be tolerated withouttolerated without irreversible damageirreversible damage 1. Reimer KA,et al. Am J Cardiol 1983;52:72A 2. Hosenpud JD, et al. J Heart Lung Transplant 2001;20;805
    6. 6. Morphological differences between pediatric/adult myocardium  In the newborn only 30% of theIn the newborn only 30% of the myocardial massmyocardial mass comprises contractilecomprises contractile tissue compared with 60% intissue compared with 60% in the maturethe mature myocardium.myocardium.  Pediatric myocardium has fewerPediatric myocardium has fewer mitochondria andmitochondria and less oxidativeless oxidative capacity.capacity.
    7. 7. Clinical differences between pediatric/adult myocardium  NNormal immature myocardiumormal immature myocardium has ahas a greater tolerance to ischemia whengreater tolerance to ischemia when compared tocompared to mature myocardiummature myocardium11 ..  HHypoxicypoxic neonatal heart is moreneonatal heart is more sensitive to ischemia than thesensitive to ischemia than the adultadult2 ..  When cWhen compared with infants,ompared with infants, childrenchildren havehave had significantly lesshad significantly less reperfusion injury and better clinicalreperfusion injury and better clinical outcomeoutcome 3 .. 1. Yano Y et al. J Thorac Cardiovasc Surg 1987;94:887 2. Kempsfor RD, et al. J Thorac Cardiovasc Surg 1989;97:856 3. Imura H, et al. Circulation 2001;103:1551
    8. 8. 1. Physiological differences between pediatric/adult myocardium  Immature myocardiumImmature myocardium 1-3  Decreased ventricular complianceDecreased ventricular compliance  Less preload reserveLess preload reserve  DecreasedDecreased sensitivity to catecholaminessensitivity to catecholamines inin immature heartsimmature hearts  Less inotropic reserve (with maximumLess inotropic reserve (with maximum adrenergic stimuli)adrenergic stimuli)  More (-) inotropic response to anestheticMore (-) inotropic response to anesthetic agentsagents  Cardiac output in pediatric patients is moreCardiac output in pediatric patients is more dependent on heart rate and sinus rhythm.dependent on heart rate and sinus rhythm.  Increase oIncrease o ff afterload will produce significantafterload will produce significant hemodynamic impairmenthemodynamic impairment 1. Teitel D, et al. J Am Coll Cardiol 1983;1:1183 2. Boudreaux JP, et al. Anesth Analg 1984;63:731 3. Caspi J, et al. Circulation 1991;84(Suppl 3):394
    9. 9. 2. Physiological differences between pediatric/adult myocardium  Immature myocardium is more sensitive toImmature myocardium is more sensitive to extracellular Ca levels than mature myocardiumextracellular Ca levels than mature myocardium 1,21,2 ..  TheThe sarcoplasmic reticulum is underdeveloped in thesarcoplasmic reticulum is underdeveloped in the pediatricpediatric heartheart  reduced storage capacity for calciumreduced storage capacity for calcium 33  The activity of the SR Ca ATPase is lower than inThe activity of the SR Ca ATPase is lower than in the adult heartthe adult heart  Antioxidant defenseAntioxidant defense systemsystem is reduced in cyanoticis reduced in cyanotic heart defectsheart defects4,54,5  Catalase ↓Catalase ↓  Superoxide dismutase ↓Superoxide dismutase ↓  Glutathione reductase ↓Glutathione reductase ↓ 1. Gombosova I, et al. Am J Physiol 1998;274:H2123 2. Boucek RJ, et al. Pediatr Res 1984;18:948 3. Boland R, et al. J Biol Chem 1974;249:612 4. Teoh KH,et al. J Thorac Cardiovasc Surg 1992; 104:159 5. del Nido PJ,et al. Circulation 1987;76:174
    10. 10. Differences between the immature and mature myocardium on primary sourse of ATP
    11. 11. Myocardial protection in pediatric cardiac surgery  Cardioplegic arrest  On-pump beating heart
    12. 12. The advantages of cardioplegia  Diastolic arrest of the contractive components and cessation of electrical activity  Reduction of metabolic activity (arrest and hypothermia)  Intermittent oxygen delivery (blood)  Maintaining acid-base balance  Maintaining high osmotic P counteracts tissue edema  Modifying reperfusion (prevention of reperfusion injury)  Reversible  Low toxicity
    13. 13. TThehe type of cardioplegiatype of cardioplegia here is still no consensus on the type of cardioplegia There are 167 different cardioplegic solutions used for only heart transplantation in USA 1 . emmy TL, et al. Ann Thorac Surg 1997;63:262
    14. 14. Cardioplegia Composition and additives  K+  Mg++  Ca++  Buffering Systems (HCO3 - , THAM)  Glutamate–aspartate  Glucose  Insulin  Oxygen-derived free radical scavengers  Superoxide dismutase, catalase,  Glutathione peroxidase,  Glutathione,  Vit E,A, ascorbate,  Allopurunol  Desferrioxamine rocainamide eta blockers (esmolol) a+ -H+ exchange inhibitor (Amiloride, Cariporide) a+ blocker (lidocaine, tetrodotoxin) -Arginine + channel openers  Aprikalim, pinacidil, nicorandil a++ channel blockers
    15. 15. Blood vs crystalloid cardioplegia rystalloid cardioplegia Delivery is simple and cheap One single shot is possible lood cardioplegia Hemoglobin is used for O2 transportation Metabolic substrates Physiological buffers Physiological osmotic P Less hemodilution Endogeneous oxygen free radical scavenger Blood C is superior to crystalloid C over 1 h* Corne AF. J Thorac Cardiovasc Surg 93:163:19872,*
    16. 16. Hypothermia Hypothermia has been used sinceHypothermia has been used since 1950 for myocardial protection1950 for myocardial protection The methods to cool the heartThe methods to cool the heart Cold cardioplegiaCold cardioplegia Systemic coolingSystemic cooling Topical myocardial cooling » damage toTopical myocardial cooling » damage to phrenic nerve !!phrenic nerve !! Less OLess O22 consumption in arrested heartconsumption in arrested heart
    17. 17. Warm cardioplegia Hypothermia -Hypothermia - depletion of myocardialdepletion of myocardial energy suppliesenergy supplies  Lichtenstein * 1989 6.5 h CC (normothermic continuous blood cardioplegia) *Lichtenstein SV et al, Lancet 1989. **Lichtenstein SV et al, Ann Thorac Surg 1991.
    18. 18. Warm and cold combined cardioplegia Warm and cold combined bloodWarm and cold combined blood cardioplegiacardioplegia Warm inductionWarm induction Cold cardioplegiaCold cardioplegia Hot shotHot shot
    19. 19. Delivery techniques Antegrade, retrograde, or combined? nterograde delivery: dvantages and disadvantages  Simple  Uniform distribution of cardioplegia  AI: poor antegrade coronary perfusion  Aortic valve or root surgery  injury to the coronary ostia
    20. 20. Delivery techniques Antegrade, retrograde, or combined? etrograde delivery: dvantages and disadvantages  Nonphysiological  Nonhomogenous distribution  Decreased flow to the right ventricle and septum  The advantage in AI and aortic root surgery  Risk of ruptere of
    21. 21. Single-dose/multi-dose/multi-dose CardioplegiaCardioplegia Single-doseSingle-dose Continuous (adult heart)Continuous (adult heart) Multi-dose cardioplegiaMulti-dose cardioplegia Cold cardioplegia every 20-30 minCold cardioplegia every 20-30 min Warm cardioplegia every 15-20 minWarm cardioplegia every 15-20 min
    22. 22. Myocardial injury after surgery  Ventricular hypertrophyVentricular hypertrophy  Pre-ischemic energy depletionPre-ischemic energy depletion  Length of the ischemic intervalLength of the ischemic interval  Incomplete myocardial protectionIncomplete myocardial protection  Ventricular distention (failure to vent the LA adequately)  Retraction and stretch injury to the myocardium  Ventriculotomy  edema (hemodilution or low colloid oncotic P)  Reperfusion injuryReperfusion injury  Coronary artery injury or embolism of airCoronary artery injury or embolism of air bubblesbubbles
    23. 23. Low output after surgery ypocalcemia, acidosis, hypoxia esiduel volume overload (VSD, PY,AY) esidual pressure overload (LVOTO,RVOTO) ardiac compression (oedema, tamponade) ecreased preload (hypovolemia, diastolic dysfunction)
    24. 24. Myocardial protection in our clinic iniplegia – Anterograde n-pump beating BDCPS, Fontan PS, PVR, TVR
    25. 25. The cystalloid composition for Miniplegia  Infusion pump composition 30 meq K+ 10 meq Mg++ 20 ml 30% dextrose  Induction [[KK++ ]] 25 meq/L25 meq/L  Maintenance [[KK++ ]] 13 meq/L13 meq/L
    26. 26. 1. Result1. Result  WhenWhen a medicala medical center decidecenter decide ss onon the myocardial protection method,the myocardial protection method, the most important determinants arethe most important determinants are thethe clinical resultsclinical results and theand the surgeons’ experiences.surgeons’ experiences.  ThThisis methodmethod shouldshould be effective,be effective, simple, cheap andsimple, cheap and shouldshould bebe accepteacceptedd byby allall surgeonssurgeons..
    27. 27. 2. Results2. Results  Myocardial protection is challengingMyocardial protection is challenging inin some casessome cases  LLongong operationsoperations  CComplexomplex operationsoperations which recurrentwhich recurrent cardioplegia delivery from thecardioplegia delivery from the openopen aortic rootaortic root isis requiredrequired  Newborn patientsNewborn patients  Preoperatively damaged myocardiumPreoperatively damaged myocardium
    28. 28. 3. Results3. Results  TheThe medicalmedical centercenter shouldshould evaluate theevaluate the protection method with respect to theprotection method with respect to the outcome in different proceduresoutcome in different procedures If the morbidity and mortality rate isIf the morbidity and mortality rate is high in especially long and complexhigh in especially long and complex procedures,procedures, thethe myocardial protectionmyocardial protection methodmethod must also be considered as amust also be considered as a risk factor.risk factor.
    29. 29. T Thank You!
    1. A particular slide catching your eye?

      Clipping is a handy way to collect important slides you want to go back to later.