1. DR.V.S.R.BHUPAL

2. PRESENTATION OVERVIEW Introduction History Indications for Surgery Surgical Technique Postoperative Physiology Postoperative IssuesGLENN SHUNT-A REVIEW 3. INTRODUCTION Atresia of an atrioventricular or semilunar valve results in single-ventricleanatomies that have complete mixing of the systemic andpulmonary venous circulations Structural defects that are generally managed with a stagedpalliation include variations of single left ventricle and variationsof single right ventricle.GLENN SHUNT-A REVIEW 4. GENERAL PRINCIPLES OF SUPERIOR AND TOTALCAVOPULMONARY CONNECTIONS Goal of surgical palliation in single-ventricle lesions - toseparate the systemic and pulmonary circuits, resulting innormal or near normal oxygen saturation. Cavopulmonary connections -used to divert systemic venousreturn directly into the pulmonary vascular bed, providing moreeffective pulmonary blood flow and reducing the volume loadon the single ventricle.GLENN SHUNT-A REVIEW 5. After these procedures, the single ventricle ejects blood only to thesystemic circuit, with pulmonary blood flow derived by passiveflow into the pulmonary vascular bed at the expense of highercentral venous pressure. Although cavopulmonary connections improve cyanosis andminimize ventricular work, the elevated PVR in the neonateprecludes their use until approximately 3 months of ageGLENN SHUNT-A REVIEW 6. The cavopulmonary connections used to stage the single-ventriclepatient to the modified Fontan1)BDG2)Hemi-Fontan. Staging to Fontan performed because of the high incidence ofpleural effusions and low-output myocardial failure when takendirectly for fontan procedure..GLENN SHUNT-A REVIEW 7. Single left ventricle physiologies Tricuspid atresia with normally related great arteries Double-inlet left ventricle with normally related great arteries Transposition of the great arteries with PS Malaligned atrioventricular canal with hypoplastic right ventricle Pulmonary atresia with intact ventricular septumGLENN SHUNT-A REVIEW 8. TRICUSPID ATRESIAGLENN SHUNT-A REVIEW 9. Single right ventricle physiologies Hypoplastic left heart syndrome [HLHS] Double-outlet right ventricle with mitral atresia Malaligned atrioventricular canal with hypoplastic left ventricle Heterotaxy syndromesGLENN SHUNT-A REVIEW 10. HYPOPLASTIC LEFT HEART SYNDROMEGLENN SHUNT-A REVIEW 11. GOALS OF STAGE 1 PALLIATIONUnobstructed systemic blood flowLimited pulmonary blood flowUndistorted pulmonary arteriesUnobstructed pulmonary venous returnMinimal atrioventricular valve regurgitationGLENN SHUNT-A REVIEW 12. Surgical palliation allows the neonate to survive into infancy but isnot a stable anatomic or physiologic long-term solution. Children with single-ventricle anatomy will ultimately undergosome variation of the Fontan operation as their final surgicalpalliationGLENN SHUNT-A REVIEW 13. Selecting Patients with Tricuspid Atresia for theFontan Procedure: The Ten Commandments1. Minimum age, 4 years2. Sinus rhythm3. Normal caval drainage4. Right atrium of normal volume5. Mean pulmonary artery pressure 15 mm Hg6. Pulmonary arterial resistance < 4 U/m27. Pulmonary-artery-to-aorta-diameter ratio 0.758. Normal ventricular functions (ejection fraction > 0.6)9. Competent left atrioventricular valve10. No impairing effects of previous shuntsGLENN SHUNT-A REVIEW 14. History In the 1950s and 1960s in Italy, the United States, and Russia, manysurgeons were concurrently discovering and harnessing the utilityof the cavopulmonary connection. An experimental model of the cavopulmonary anastomosis wasused in dogs by Carlon in the 1950s. This model identified many of the hemodynamic and surgicaladvantages of the cavopulmonary anastomosis relative to theBlalock-Taussig shunt.GLENN SHUNT-A REVIEW 15. The first significant clinical use of the cavopulmonary anastomosisin the United States was performed by Glenn. He used unidirectional (classic) and bidirectional superiorcavopulmonary anastomoses and inferior cavopulmonaryanastomosis (inferior vena cava [IVC]-to-PA connection). Interim palliation with a BDG shunt has now become the standardof care over the past decade, typically in infancy (4 to 9 months ofage).GLENN SHUNT-A REVIEW 16. DR WILLIAM GLENNGLENN SHUNT-A REVIEW 17. GLENN SHUNT-A REVIEW 18. Timing of shunt With a decrease in PVR, infants with single ventricle who have had aneonatal palliation become candidates for the superiorcavopulmonary anastomoses by 3 to 6 months of age. Mahle and associates showed that early ventricular unloading afterneonatal single-ventricle palliation improved aerobic exerciseperformance in preadolescents with the Fontan palliation. An additional advantage of an early superior cavopulmonaryanastomosis is the opportunity to address distorted pulmonaryarteries from previous bands or shunts and to create a betterdistribution of PA blood flow and growth of the pulmonary vascularbed.GLENN SHUNT-A REVIEW 19. Indications for early shunt procedure Cyanosis secondary to inadequate pulmonary blood flow afterneonatal palliationCongestive heart failure from an excessive volume load caused bysevere atrioventricular valve regurgitation or by an elevated Qp:Qs.GLENN SHUNT-A REVIEW 20. The benefits of early cavopulmonary anastomosis must be weighedagainst the risks of elevated SVC pressure and cyanosis. Bradley and colleagues found that cavopulmonary anastomosis atyounger than 3 months was associated with lower oxygen saturationin the early postoperative period and a risk of PA thrombosis. Some infants with severe ventricular dysfunction oratrioventricular valve regurgitation may not be suitable for furtherstaged palliation and may require heart transplantationGLENN SHUNT-A REVIEW 21. Prerequisites before the procedure Echocardiogram Cardiac catheterizationFor anatomic and hemodynamic assessment of the Pulmonary arteries, Aortic arch Ventricular and atrioventricular valve function Caval anatomy-Presence of decompressing veins that mayresult in cyanosis after superior cavopulmonaryanastomosis.GLENN SHUNT-A REVIEW 22. CLASSIC GLENN SHUNTDr. Glenn described an anastomosis between the transecteddistal end of the right pulmonary artery and theside of the SVC, which is ligated distal to the anastomosis.The azygous vein is ligated to prevent itsdecompressing flow from the SVC.GLENN SHUNT-A REVIEW 23. BIDIRECTIONAL GLENN SHUNTThe BDG operation is performed via mediansternotomy . At the initiation of cardiopulmonarybypass (CPB), the shunt is ligated with a vascular clipor ligature. Preservation of the proper spatialorientation of the SVC relative to the PA is essential.Therefore the azygos vein is ligated but not divided.The SVC is then divided, and the cardiac end isoversewn. The cephalic end is anastomosed end to sideto the ipsilateral PA.GLENN SHUNT-A REVIEW 24. As with the classic glenn shunt, the bi-directional cavo-pulmonary shuntis far less likely to engender Pulmonary vascular obstructive diseasecompared with systemic-pulmonary shunts, and there is minimalDistortion of the pulmonary artery architecture.GLENN SHUNT-A REVIEW 25. Shunt between the Superior Vena Cava and Right Pulmonary Artery Technic of Anastomosis.Glenn WW. N Engl J Med 1958;259:117-120. 26. Angiogram Taken Two Months after Operation.Glenn WW. N Engl J Med 1958;259:117-120. 27. Arterial Oxygen Studies before and after the Shunt.*Glenn WW. N Engl J Med 1958;259:117-120. 28. Technique Without Cardiopulmonary BypassBDG may be performed without the utilization of CPB. Patients with sources of pulmonary blood flow that do not needinterruption as part of the cavopulmonary anastomosis (antegradeflow through a stenotic pulmonary valve or banded PA) and have nospecific intracardiac pathology requiring revision are candidates forcavopulmonary anastomosis without CPB. HLHS patients are not candidates for superior cavopulmonaryanastomosis without CPB because their pulmonary blood flow isshunt dependent, and because they may require PA reconstructionand other intracardiac procedures at the time of their superiorcavopulmonary anastomosisGLENN SHUNT-A REVIEW 29. HEMI FONTAN PROCEDUREGLENN SHUNT-A REVIEW 30. FONTAN PROCEDUREdUdekem Y et al. Circulation 2007;116:I-157-I-164Copyright American Heart Association, Inc. All rights reserved. 31. GLENN SHUNT-A REVIEW 32. GLENN SHUNT-A REVIEW 33. Postoperative Physiology After completion of the superior cavopulmonary anastomosis, thecirculation to the lungs is from the upper body systemic venousreturn. The pulmonary blood flow results from upper body blood flow,allSVC return must pass through the lungs to reach the heart in theabsence of decompressing venous collaterals.GLENN SHUNT-A REVIEW 34. The principal physiologic advantage of conversion to a superiorcavopulmonary anastomosis at an early age is the reduction of thevolume work of the single ventricle and a predictable Qp:Qs ofapproximately 0.6 to 0.7. This ratio is higher in young infants because of the relative size ofthe head and the upper extremities in young infants as opposed tothose in older children, but in general, systemic arterial oxygensaturations (SaO2) are 75% to 85%.GLENN SHUNT-A REVIEW 35. The immediate reduction in the volume load of the single ventricleby removing the aortopulmonary shunt decreases the work of thesingle ventricle and may improve long-term atrio-ventricular valveand myocardial function. Atrioventricular valve regurgitation resulting from physiologicrather than structural abnormalities may decrease as theventricular geometry normalizesGLENN SHUNT-A REVIEW 36. After superior cavopulmonary anastomosis, oxygen is deliveredmore efficiently to the body because only deoxygenated blood fromthe SVC rather than admixed blood from the ventricle is presentedto the lungs for oxygen uptake. The net result of the more efficient oxygen uptake in the lungs is areduction in cardiac output needed to achieve a given tissue O2deliveryGLENN SHUNT-A REVIEW 37. DIASTOLIC DYSFUNCTIONGLENN SHUNT-A REVIEW 38. After the BDG or hemi-Fontan, ventricular filling is not absolutelydependent on pulmonary venous return, because IVC flow is stilldiverted directly to the single ventricle and maintains preload. As a result, the acute volume reduction noted after superiorcavopulmonary anastomosis is better tolerated than in the case oftransitioning a child from a neonatal palliation directly to theFontan completion without an intervening superior cavopulmonaryanastomosisGLENN SHUNT-A REVIEW 39. SaO2 after creation of a BDG shunt tends to be lower in very youngyounger than 3 months patients. Although some patients as young as 4 weeks have had satisfactory BDGshunt creation, patients younger than 3 months have a higher incidenceof early cyanosis, PA thrombosis, and vascular congestion. Therefore a delay of the procedure until the child is older than 3 monthsis generally recommended. By age 6 months, the mortality risk approaches 0 in many centers.GLENN SHUNT-A REVIEW 40. Postoperative IssuesGLENN SHUNT-A REVIEW 41. Mechanical Ventilation Positive pressure ventilation with increased mean airway pressuresadversely affects PVR and ventricular filling Early institution of spontaneous ventilation improveshemodynamics in the awake patient. Spontaneous breathing also increases pco2, which will promoteincreased cerebral blood flow and, thereby, increase pulmonaryblood flow.GLENN SHUNT-A REVIEW 42. Physiologic (3 to 5 cm H2O) positive end-expiratory pressure(PEEP) is generally well tolerated, does not significantly affect PVRor cardiac output, and may improve oxygenation by reducing areasof microatelectasis, reestablishing functional residual capacity, andimproving ventilation/perfusion matching.GLENN SHUNT-A REVIEW 43. Elevated Cavopulmonary Pressures The goal of postoperative cavopulmonary anastomosis management isto minimize the transpulmonary gradient (PA mean pressure common atrium mean pressure) to allow passive pulmonary bloodflow through the lungs and back to the single ventricle. An elevated transpulmonary gradient may result from pulmonaryvenous obstruction, elevated PVR, or pleural effusion, hemothorax, orpneumothorax. Extubating the patient expeditiously will reduce the common atrialpressure and promote flow through the lungs by creating a greatertransthoracic gradient from the extrathoracic space to theintrathoracic space. Diminished cavopulmonary blood flow will reduce systemic SaO2GLENN SHUNT-A REVIEW 44. Elevation of PVR from the inflammatory effects of CPB may beminimized with pulmonary vasodilators such as nitric oxide at 5to 20 parts per million in inspired gas. Mild facial edema after superior cavopulmonary anastomosismay persist for up to 72 hours. Majority of pleural effusions after superior cavopulmonaryanastomosis will diminish over time with judicious diuretic useand fluid restriction.GLENN SHUNT-A REVIEW 45. Patients are typically given aspirin (5 mg/kg/day) after superiorcavopulmonary anastomosis to reduce the risk of thrombosis ofthe superior cavopulmonary circuitGLENN SHUNT-A REVIEW 46. Patients with clinical signs of significantly elevated SVC pressure,upper extremity plethora and edema may have obstruction at thecavopulmonary anastomosis, distal PA distortion, or markedelevations in PVR. Significant elevations of pressure in the SVC may limit cerebralblood flow. If the SVC pressure is more than 18 mm Hg, the etiology should bepromptly investigated, including early catheterization, if necessaryGLENN SHUNT-A REVIEW 47. Hypertension and Bradycardia Transient postoperative hypertension and bradycardia have beenfrequently observed in the first 24 to 72 hours after thecavopulmonary shunt. Hypertension may be due to pain, catecholamine secretion,intracranial hypertension, or a combination of these. The acute elevation of the central venous pressure may result ina reflex similar to that seen in head trauma, such that systemichypertension is necessary to preserve adequate cerebralperfusion. Therefore aggressive lowering of the blood pressure mayadversely affect the cerebral perfusion pressure, and vasodilatorsshould be used cautiously.GLENN SHUNT-A REVIEW 48. Transient bradycardia is typically seen after a cavopulmonaryconnection and may be due to the acute reduction of the volumeload of the single ventricle, or may be due to injury to the sinusnode or its arterial supply.GLENN SHUNT-A REVIEW 49. Low Cardiac Output When the child has preexisting ventricular dysfunction or severeatrio-ventricular valve regurgitation. In these volume-loaded ventricles, which need high fillingpressures to generate adequate output, volume reduction and theeffects from CPB may significantly reduce cardiac output andoxygen delivery to the tissues.GLENN SHUNT-A REVIEW 50. Cyanosis Excessive hypoxemia (SpO2