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Acute Ascending Aortic Dissection 41 Years After Mustard Procedure
Acute Ascending Aortic Dissection 41 Years After Mustard Procedure Andrea Nowitz, MBBCh, BSc(Med)(Hons), FANZCA, LLB
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CASE OF ACUTE ascending aortic dissection in a 42year-old woman not known at the time of presentation to have undergone a balloon atrial septostomy at 7 weeks of age for complete transposition of the great arteries (d-TGA) followed by a Mustard procedure 16 months later is presented. Aortic dissection has not been described previously in atrial switch procedures for d-TGA in long-term outcome studies.1-6 Although patients with congenital heart disease (CHD) who survive to adulthood are best managed at specialist centers, increasingly these patients may present with acute, life-threatening cardiac emergencies to any cardiac surgical unit. The relevant anatomy and course of a corrected d-TGA can lead to a systematic approach to cardiac anatomy on transesophageal echocardiography (TEE) in an emergency. Approval for the retrieval of medical records and publication of this report was obtained from the relevant regional ethics committees. CASE REPORT A previously well, slim 42-year-old woman of small stature presented with sudden onset of sharp thoracic back pain radiating to the central chest while smoking. On examination, she was calm, conscious, and breathing spontaneously. She was hemodynamically stable with a regular pulse rate of 65 beats/min, and her blood pressure was 128/43 mmHg on the right upper arm and 125/42 mmHg on the left upper arm. A 12-lead electrocardiogram showed sinus rhythm with a leftward axis and T-wave inversion in the precordial leads. A computed tomography angiogram showed a type-1 aortic dissection involving an aneurysmal aortic root and extending to the common iliac arteries. There were no sternal wires visible on the scout scan, but the aneurysmal aortic root was notable for its adherence to the posterior aspect of the sternum. The patient reported that she had had closure of a patent foramen ovale (PFO) as an infant in a neighboring country. She had 3 children, 2 of whom had been normal deliveries, and she was taking an oral contraceptive pill. Apart from being a smoker, she had no other medical history, and until presentation her functional capacity was New York Heart Association class I. After the induction of anesthesia, a multiplane TEE probe was inserted, and images were acquired on a Philips iE33 machine (Philips Medical Systems, Bothell, WA). Femoral-femoral bypass was initiated before redo median sternotomy. During cannulation of the femoral vessels, a TEE examination was performed. Attention initially was directed to the upper esophageal (UE) longaxis (LAX) view to define the anatomy of the root aneurysm, the proximal extent of the dissection, and the involvement of the aortic valve to assist with surgical decision making before the onset of cardiopulmonary bypass (CPB). With the depth setting at 10 cm, it was not apparent immediately on TEE that the aorta was anterior to the pulmonary artery because of the size of the aortic root and the ascending aorta. The pulmonary artery initially was identified mistakenly as the aorta. The suspicion of abnormal anatomy was raised when a few scattered reflections consistent with air bubbles appeared in what appeared to be the aorta at the same time that drugs were administered by injection into the right internal jugular central venous catheter. At a depth setting of 12 cm, it clearly was evident that the 2 great vessels lay parallel to each other with the aorta anterior and to the left of the pulmonary artery. The posterior vessel was then recognized to be the pulmonary artery (Fig 1 and Video 1 [supplementary videos are available online]). A linear artifact accounting for any apparent double image was ruled out because of the difference in size of the 2 structures, their independent movement, the relative distances of the relevant wall
reflections from the transducer, and the presence of a characteristic flap within the aortic lumen. The aortic root and ascending aorta were severely dilated. The dissection flap was visible in the ascending aorta and extended proximally into the coronary sinuses. The aortic valve was tricuspid, and the leaflets were not involved in the dissection. The application of colorflow Doppler (CFD) showed severe aortic regurgitation secondary to dilation of the coronary sinuses and effacement of the sinotubular junction (Fig 2 and Video 2) with no pulmonary regurgitation evident. In the midesophageal (ME) 4-chamber (4C) view, heavy trabeculation and the presence of a moderator band confirmed that a hypertrophied and enlarged ventricle situated to the right of the interventricular septum was the morphologic right ventricle (Fig 3 and Video 3). The morphology of the small and vigorous left ventricle was confirmed by its elongated cavity and smooth endocardial surface. This normal anatomic arrangement was confirmed in the transgastric short-axis view in which the left ventricle was noted to have a crescent shape caused by right ventricular enlargement (Fig 4 and Video 4). Despite the anomaly of the ventricles being in the anatomically correct positions, a working diagnosis of a congenitally corrected TGA was made given the history of PFO closure and the patient’s otherwise unremarkable medical history. Attention was directed to defining what additional abnormal cardiac anatomy had required a PFO closure to result in normal physiologic blood flow in a patient with TGA. Interrogation of the path of the flow of blood to the appropriate physiologic ventricles proved difficult. The presence of microbubbles in the pulmonary artery after the injection of drugs into the right internal jugular central venous catheter suggested that systemic venous return was being delivered to the pulmonary circulation through the left-sided atrial chamber, left ventricle, and pulmonary artery. In the ME 4C view, the bright and thickened interatrial septum was attributed to the history of PFO closure. The mitral valve was confirmed as being in its normal basal position relative to the tricuspid valve (Fig 3). The application of CFD to the ME 4C view identified that blood from the right-sided atrial chamber entered the right ventricle through the tricuspid valve and blood from the left-sided atrial chamber entered the left ventricle through the mitral valve (Fig 5). The conduit created by an unrecognized atrial baffle to direct systemic venous return to the left ventricle through the mitral valve mistakenly was interpreted as turbulent flow through the left atrium being compressed by the dilated aorta. This error in interpretation was repeated in the ME inflow-outflow view at 53° where the atrial baffle was thought to be the posterior wall of the left atrium (Video 5). The findings were conveyed to the surgeon and reviewed and confirmed by a cardiologist. After an uneventful median sternotomy, the surgeon identified a 7-cm aneurysm of the aorta arising from the right ventricle with an adequate neck before the arch. Extensive adhesions were divided over the aorta, anterior (right) ventricle, and right-sided atrium only. On direct inspection, the atrial anatomy was unclear and
From the Department of Anesthesia, Princess Alexandra Hospital, Brisbane, Queensland, Australia. Address reprint requests to Andrea Nowitz, MBBCh, BSc(Med)(Hons), FANZCA, LLB, Department of Anesthesia, Princess Alexandra Hospital, 199 Ipswich Road, Brisbane, Queensland, Australia. E-mail: [email protected] © 2013 Elsevier Inc. All rights reserved. 1053-0770/2704-0001$36.00/0 http://dx.doi.org/10.1053/j.jvca.2012.04.006 Key words: transposition of great vessels, Mustard procedure, aortic dissection, heart defects, congenital
Journal of Cardiothoracic and Vascular Anesthesia, Vol 27, No 4 (August), 2013: pp 735-739
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Fig 1. The UE LAX view: the 2 great vessels lie parallel to each other with the aorta anterior to the pulmonary artery. Microbubbles are visible in the pulmonary artery, and the dissection flap is visible in the dilated aorta.
not fully explored. Coronary sinus cannulation for retrograde cardioplegia was attempted through the right-sided atrial chamber, but the blood evidently was well oxygenated and the coronary sinus orifice could not be located with certainty. Therefore, further efforts at coronary sinus cannulation were abandoned. After opening the aortic root, the intimal tear was identified just above the sinotubular junction. The aortic valve leaflets were morphologically normal, but the positions were reversed with the noncoronary cusp placed anteriorly. A valve-sparing root replacement with coronary reimplantation was performed. The cross-clamp time was 249 minutes followed by multiple repeated episodes of ventricular fibrillation treated with electric and pharmacologic methods until the eventual return of sinus rhythm. Weaning from CPB was gradual, with the requirement of multiple, high-dose inotropes. The total CPB time was 347 minutes. The systemic right ventricular ejection fraction was estimated to be ⬍10% on TEE after CPB, and after an episode of near-cardiac standstill requiring internal cardiac massage, an intraaortic balloon pump was placed via the right common femoral artery with some improvement. Hemostasis was achieved, but the sternum
Fig 2. The UE LAX view with CFD: severe aortic regurgitation was present secondary to dilation of the coronary sinuses and effacement of the sinotubular junction. (Color version of figure is available online.)
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Fig 3. The ME 4C view: the atrioventricular valves are associated with their appropriate ventricles, and the tricuspid valve is seen to be more apically placed than the mitral valve.
could not be closed because of hemodynamic instability from right ventricular compression. The sternum was stented open and the wound packed and sealed for transfer of the patient to the intensive care unit. Shortly after arrival in the intensive care unit, the patient arrested and, despite emergency sternal reopening and prolonged full resuscitative efforts, could not be revived. DISCUSSION
d-TGA is the most common cause of cyanotic CHD.1,2,7 Associated lesions may include a ventriculoseptal defect, pulmonary outflow tract obstruction, and, less commonly, coarctation of the aorta.1,7 Simple d-TGA is defined as situs solitus with atrioventricular concordance and ventriculoarterial discordant connections.5 The aorta arises from a right-sided, morphologic right ventricle and lies anterior and parallel to the pulmonary artery, which itself arises from a left-sided, morphologic left ventricle.7 Without palliation and subsequent correction, 50% will die within the first month of life and 89% in their first year.2 Historically, newborns with insufficient or no communica-
Fig 4. The transgastric short-axis view: heavy trabeculation confirmed that the hypertrophied and enlarged ventricle to the right of the interventricular septum was the right ventricle.
ACUTE ASCENDING AORTA DISSECTION
Fig 5. The ME 4C view with CFD: blood from the right-sided atrial chamber enters the right ventricle through the tricuspid valve and blood from the left-sided atrial chamber enters the left ventricle through the mitral valve. The presence of the baffle was unrecognized. (Color version of figure is available online.)
tion between the systemic and pulmonary circulations initially required a percutaneous Rashkind balloon atrial septostomy or a Blalock-Hanlon surgical atrial septectomy to improve oxygenation until a corrective procedure could be performed.7 Corrective but palliative surgeries during the 1960s (the Senning procedure) and the 1970s (the Mustard procedure) for d-TGA in infants who reached a reasonable size after atrial septostomy are known as atrial switch procedures. These procedures involved directing the systemic venous return to the left ventricle and pulmonary venous return to the right ventricle through an atrial baffle to restore normal physiologic blood flow.8,9 In the mid-1970s, it was recognized that atrial switch procedures were complicated by early right ventricular failure and tricuspid valve insufficiency because of the limitations of the right ventricle to function permanently as a systemic ventricle. The Jatene procedure was described to perform a definitive arterial switch procedure in the first 2 weeks of life to restore the normal anatomic arrangement of the aorta from the left ventricle and the pulmonary artery from the right ventricle.10 This is now the currently preferred surgery if the d-TGA anatomy is appropriate. The long-term outcomes after atrial switch procedures for d-TGA have been well documented for up to 3 decades.4-6 Survival of 80% at 28 years has been reported in patients with a Mustard atrial baffle procedure for simple d-TGA.5 The course of survival after atrial switch procedures may be complicated by the loss of sinus node function, atrial rhythm disturbances, tricuspid regurgitation, eventual right ventricular dysfunction, right ventricular failure, and late sudden death.46,11 Surgical complications include venous (both systemic and pulmonary) obstruction and baffle obstruction, or leak.11 Regular surveillance is indicated at specialized centers for timely interventions including surgery, medical therapy, pacemaker or automatic implantable cardioversion device implantation.6,7,12 In patients in whom right ventricular function is deteriorating, cardiac transplantation may be required.7,12 Specifically, patients with atrial switch procedures require fol-
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low-up with magnetic resonance imaging, which provides better information than transthoracic echocardiography (TTE) of right ventricular function and venous pathways.5,6 Magnetic resonance imaging is also more likely to detect dilation of the anteriorly placed ascending aorta, which may be missed on surveillance with TTE alone. Aortic dissection has not been described previously in longterm outcome studies of atrial switch procedures for d-TGA.1-6 Aortic dilation and dissection normally would not be associated with d-TGA unless the aortic valve was bicuspid or incompetent, but interest in the structural and functional integrity of the great arterial walls recently has focused on histologic examination of their specific medial constituents.13-15 Great arteries in CHD may dilate out of proportion to hemodynamic or morphogenetic expectations, may become aneurysmal, or may rupture.15 In a descriptive study of structural abnormalities of great arterial walls in CHD, the media of the dilated ascending aorta above the bicuspid aortic valves was found to be consistently abnormal whether the valves were stenotic, incompetent, or functionally normal, and all paracoarctation aortic biopsies had medial abnormalities.15 Histologic medial abnormalities in normal-sized ascending aortas were also described in 8 neonates with d-TGA in the study. These abnormalities of the medial wall of the ascending aorta in patients with d-TGA may herald a late aneurysmal change of the ascending aorta.15,16 Pregnancy has been identified as an independent variable for the structural change of the aortic media, but the extent to which these changes normalize after delivery and whether gestational changes are additive to those described in female patients with CHD who have reached reproductive age are not known.15 In the presented case, intraoperative transesophageal echocardiographic examination specifically ruled out the presence of a bicuspid aortic valve, but with adequate depth settings in the UE LAX view, aortic dilation was obvious. In the patient’s subsequently retrieved available records to the year 2000, there was no comment on the progression of size, if any, of the ascending aorta. Trivialto-mild aortic valve regurgitation was documented on TTE only during the patient’s pregnancies before 1996. However, the last available reported TTE from 2000, when the patient was not pregnant, did document trivial aortic regurgitation without reference to aortic size. Aortic root aneurysm has been reported after the surveillance of a 30-year-old man who had undergone a Mustard procedure at 2 years of age.16 In that case, elective aortic valve–sparing surgery was performed successfully for an aortic root measuring 4.5 cm and progressive volume overload of the functional left ventricle with a slightly impaired ejection fraction. Valvesparing surgeries originally were described for aortic valve incompetence and aneurysm of the ascending aorta, but favorable long-term results have been achieved in patients with Marfan syndrome and acute aortic dissection.16 In 1975, it was reported that the term “transposition” used to describe a variety of relations of the great arteries was a nonspecific term and should be reserved to describe the situation in which both great arteries arise from separate morphologically inappropriate ventricles.17 The authors described 4 anomalous hearts in which the great arteries arose
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in an unusual fashion from morphologically appropriate ventricles but there was atrioventricular concordance. In 1 of the anomalies described as an anatomically corrected malposition, patients presented with a left-sided anterior aorta, which must be distinguished from the left-sided anterior aorta more frequently encountered in congenitally corrected transposition (CC-TGA). The identification of cardiac anatomy is based on the segmental morphologic analysis of the venoarterial sequence (ie, the determination of the visceroatrial situs and atrioventricular and ventriculoarterial connections).18 d-TGA is characterized by atrioventricular concordance and ventriculoarterial discordance, whereas CC-TGA is characterized by atrioventricular and ventriculoarterial discordance, the latter resulting in a physiologically normal flow of blood through the chambers. Cardiac situs is determined by the laterality of the atria to the interatrial septum, specifically, by the position of the morphologic right atrium; the normal condition is the morphologic right atrium to the right of the interatrial septum.18,19 The right atrium is recognized by a large, pyramidal appendage and confirmed by the presence of the great veins and coronary sinus.19 In the presented case, these specific features could not be readily appreciated on TEE, and the presence of adhesions and the institution of femoral-femoral bypass limited the confirmation of those features by direct surgical inspection. Specifically, the coronary sinus could not be located with certainty by the surgeon through the presumed right atrium, confounding the ability to confirm atrial situs. The left atrium is characterized by a tapered, tubular appendage and the presence of pulmonary veins.18,19 In the presented case, the small size and apparent compression of the left-sided atrial chamber were thought to be from distortion by the massively dilated aorta. The presence of an atrial baffle was not recognized to be the reason CFD showed the flow of blood across the tricuspid valve from a right-sided atrial chamber into the right ventricle and across the mitral valve from a left-sided atrial chamber into the left ventricle even though it had been
established that systemic venous return was being directed through the mitral valve to the left ventricle and to the pulmonary circulation. The patient was not known preoperatively to have had surgically corrected d-TGA, but, in hindsight, the working diagnosis of CC-TGA could not have been supported because of the normal anatomic position of the ventricles. The diagnosis of an anatomically corrected malposition also could not be supported because even if atrioventricular concordance had been confirmed there was ventriculoarterial discordance in keeping with transposition and not malposition as the reason for the leftsided anterior aorta. In these circumstances, the physiologically normal blood flow suggested at least a form of corrected transposition, and, in the absence of a misleading history of PFO closure, the diagnosis of an atrial switch procedure for d-TGA may have been made correctly. The presented case highlights several issues in the increasing population of patients with CHD, with or without operative interventions, surviving more than 3 decades. First, these patients require lifelong surveillance at centers with the necessary specialist services.12 Second, patients with a variety of forms of complex CHD, irrespective of whether they have had surgical intervention or not, have histologic abnormalities of the medial constituents of the arterial walls and are at an increased risk for aortic abnormalities predisposing to dilation, aneurysm, rupture, and, as presented in this case, dissection.13,15,16 Third, patients with CHD can present with acute life-threatening conditions to any cardiac surgical unit, and, if appropriate information or expertise is not immediately available, a systematic approach to the application of the fundamental principles of the identification of cardiac anatomy using TEE should be adopted.11,18,19 ACKNOWLEDGMENT The author thanks Dr Kirsten Finucane, ONZM, Chief Surgeon of the Paediatric and Congenital Cardiac Service at Starship Hospital, Auckland, New Zealand.
REFERENCES 1. Liebman J, Cullum L, Belloc NB: Natural history of transposition of the great arteries: Anatomy and birth and death characteristics. Circulation 40:237-262, 1969 2. Campbell M: Natural history of cyanotic malformations and comparison of all common cardiac malformations. Br Heart J 34:3-8, 1972 3. Van der Horst RL, Gotsman MS: The spectrum and natural history of complete transposition of the great arteries. S Afr Med J 47:553-558, 1973 4. Gelatt M, Hamilton RM, McCrindle BW, et al: Arrhythmia and mortality after the Mustard procedure: A 30-year single-center experience. J Am Coll Cardiol 29:194-201, 1997 5. Wilson NJ, Clarkson PM, Barratt-Boyes BG, et al: Long-term outcome after Mustard repair for simple transposition of the great arteries. J Am Coll Cardiol 32:758-765, 1998 6. Roos-Hesselink JW, Meijboom FJ, Spitaels SE, et al: Decline in ventricular function and clinical condition after Mustard repair for transposition of the great arteries (a prospective study of 22-29 years). Eur Heart J 25:1264-1270, 2004
7. Warnes CA: Transposition of the great arteries. Circulation 114: 2699-2709, 2006 8. Senning A: Surgical correction of transposition of the great arteries. Surgery 45:966-980, 1959 9. Mustard WT: Successful two-stage correction of transposition of the great vessels. Surgery 55:469-472, 1964 10. Jatene AD, Fontes VF, Paulista PP, et al: Anatomic correction of transposition of the great vessels. J Thorac Cardiovasc Surg 72:364370, 1976 11. Russell IA, Rouine-Rapp K, Stratmann G, et al: Congenital heart disease in the adult: A review with internet-accessible transesophageal echocardiographic images. Anesth Analg 102:694-723, 2006 12. Deanfield J, Thaulow E, Warnes C, et al: Guidelines. Management of grown up congenital heart disease. Eur Heart J 24:1035-1084, 2003 13. Roberts WC, Vowels TJ, Ko JM, et al: Comparison of the structure of the aortic valve and ascending aorta in adults having aortic valve replacement for aortic stenosis versus pure aortic regurgitation and resection of the ascending aorta for aneurysm. Circulation 123:896-903, 2011 14. Michelena HI, Khanna AD, Mahoney D, et al: Incidence of
ACUTE ASCENDING AORTA DISSECTION
aortic complications in patients with bicuspid aortic valves. JAMA 306:1104-1112, 2011 15. Niwa K, Perloff JK, Bhuta SM, et al: Structural abnormalities of great arterial walls in congenital heart disease: Light and electron microscopic analysis. Circulation 103:393-400, 2001 16. Ono M, Goerler H, Boethig D, et al: Valve-sparing operation for aortic root aneurysm late after Mustard procedure. Ann Thorac Surg 83:2224-2226, 2007
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17. Anderson RH, Becker AE, Losekoot TG, et al: Anatomically corrected malposition of great arteries. Br Heart J 1975:993-1013 18. Gologorsky E, Gologorsky A, Giquel J, et al: An adult patient with congenitally corrected transposition of the great arteries. Anesth Analg 111:1122-1124, 2010 19. Baum VC, Duncan PN: When right is right and when it’s not: Laterality in cardiac structures. Anesth Analg 113:13341336, 2011
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CASE OF ACUTE ascending aortic dissection in a 42year-old woman not known at the time of presentation to have undergone a balloon atrial septostomy at 7 weeks of age for complete transposition of the great arteries (d-TGA) followed by a Mustard procedure 16 months later is presented. Aortic dissection has not been described previously in atrial switch procedures for d-TGA in long-term outcome studies.1-6 Although patients with congenital heart disease (CHD) who survive to adulthood are best managed at specialist centers, increasingly these patients may present with acute, life-threatening cardiac emergencies to any cardiac surgical unit. The relevant anatomy and course of a corrected d-TGA can lead to a systematic approach to cardiac anatomy on transesophageal echocardiography (TEE) in an emergency. Approval for the retrieval of medical records and publication of this report was obtained from the relevant regional ethics committees. CASE REPORT A previously well, slim 42-year-old woman of small stature presented with sudden onset of sharp thoracic back pain radiating to the central chest while smoking. On examination, she was calm, conscious, and breathing spontaneously. She was hemodynamically stable with a regular pulse rate of 65 beats/min, and her blood pressure was 128/43 mmHg on the right upper arm and 125/42 mmHg on the left upper arm. A 12-lead electrocardiogram showed sinus rhythm with a leftward axis and T-wave inversion in the precordial leads. A computed tomography angiogram showed a type-1 aortic dissection involving an aneurysmal aortic root and extending to the common iliac arteries. There were no sternal wires visible on the scout scan, but the aneurysmal aortic root was notable for its adherence to the posterior aspect of the sternum. The patient reported that she had had closure of a patent foramen ovale (PFO) as an infant in a neighboring country. She had 3 children, 2 of whom had been normal deliveries, and she was taking an oral contraceptive pill. Apart from being a smoker, she had no other medical history, and until presentation her functional capacity was New York Heart Association class I. After the induction of anesthesia, a multiplane TEE probe was inserted, and images were acquired on a Philips iE33 machine (Philips Medical Systems, Bothell, WA). Femoral-femoral bypass was initiated before redo median sternotomy. During cannulation of the femoral vessels, a TEE examination was performed. Attention initially was directed to the upper esophageal (UE) longaxis (LAX) view to define the anatomy of the root aneurysm, the proximal extent of the dissection, and the involvement of the aortic valve to assist with surgical decision making before the onset of cardiopulmonary bypass (CPB). With the depth setting at 10 cm, it was not apparent immediately on TEE that the aorta was anterior to the pulmonary artery because of the size of the aortic root and the ascending aorta. The pulmonary artery initially was identified mistakenly as the aorta. The suspicion of abnormal anatomy was raised when a few scattered reflections consistent with air bubbles appeared in what appeared to be the aorta at the same time that drugs were administered by injection into the right internal jugular central venous catheter. At a depth setting of 12 cm, it clearly was evident that the 2 great vessels lay parallel to each other with the aorta anterior and to the left of the pulmonary artery. The posterior vessel was then recognized to be the pulmonary artery (Fig 1 and Video 1 [supplementary videos are available online]). A linear artifact accounting for any apparent double image was ruled out because of the difference in size of the 2 structures, their independent movement, the relative distances of the relevant wall
reflections from the transducer, and the presence of a characteristic flap within the aortic lumen. The aortic root and ascending aorta were severely dilated. The dissection flap was visible in the ascending aorta and extended proximally into the coronary sinuses. The aortic valve was tricuspid, and the leaflets were not involved in the dissection. The application of colorflow Doppler (CFD) showed severe aortic regurgitation secondary to dilation of the coronary sinuses and effacement of the sinotubular junction (Fig 2 and Video 2) with no pulmonary regurgitation evident. In the midesophageal (ME) 4-chamber (4C) view, heavy trabeculation and the presence of a moderator band confirmed that a hypertrophied and enlarged ventricle situated to the right of the interventricular septum was the morphologic right ventricle (Fig 3 and Video 3). The morphology of the small and vigorous left ventricle was confirmed by its elongated cavity and smooth endocardial surface. This normal anatomic arrangement was confirmed in the transgastric short-axis view in which the left ventricle was noted to have a crescent shape caused by right ventricular enlargement (Fig 4 and Video 4). Despite the anomaly of the ventricles being in the anatomically correct positions, a working diagnosis of a congenitally corrected TGA was made given the history of PFO closure and the patient’s otherwise unremarkable medical history. Attention was directed to defining what additional abnormal cardiac anatomy had required a PFO closure to result in normal physiologic blood flow in a patient with TGA. Interrogation of the path of the flow of blood to the appropriate physiologic ventricles proved difficult. The presence of microbubbles in the pulmonary artery after the injection of drugs into the right internal jugular central venous catheter suggested that systemic venous return was being delivered to the pulmonary circulation through the left-sided atrial chamber, left ventricle, and pulmonary artery. In the ME 4C view, the bright and thickened interatrial septum was attributed to the history of PFO closure. The mitral valve was confirmed as being in its normal basal position relative to the tricuspid valve (Fig 3). The application of CFD to the ME 4C view identified that blood from the right-sided atrial chamber entered the right ventricle through the tricuspid valve and blood from the left-sided atrial chamber entered the left ventricle through the mitral valve (Fig 5). The conduit created by an unrecognized atrial baffle to direct systemic venous return to the left ventricle through the mitral valve mistakenly was interpreted as turbulent flow through the left atrium being compressed by the dilated aorta. This error in interpretation was repeated in the ME inflow-outflow view at 53° where the atrial baffle was thought to be the posterior wall of the left atrium (Video 5). The findings were conveyed to the surgeon and reviewed and confirmed by a cardiologist. After an uneventful median sternotomy, the surgeon identified a 7-cm aneurysm of the aorta arising from the right ventricle with an adequate neck before the arch. Extensive adhesions were divided over the aorta, anterior (right) ventricle, and right-sided atrium only. On direct inspection, the atrial anatomy was unclear and
From the Department of Anesthesia, Princess Alexandra Hospital, Brisbane, Queensland, Australia. Address reprint requests to Andrea Nowitz, MBBCh, BSc(Med)(Hons), FANZCA, LLB, Department of Anesthesia, Princess Alexandra Hospital, 199 Ipswich Road, Brisbane, Queensland, Australia. E-mail: [email protected] © 2013 Elsevier Inc. All rights reserved. 1053-0770/2704-0001$36.00/0 http://dx.doi.org/10.1053/j.jvca.2012.04.006 Key words: transposition of great vessels, Mustard procedure, aortic dissection, heart defects, congenital
Journal of Cardiothoracic and Vascular Anesthesia, Vol 27, No 4 (August), 2013: pp 735-739
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Fig 1. The UE LAX view: the 2 great vessels lie parallel to each other with the aorta anterior to the pulmonary artery. Microbubbles are visible in the pulmonary artery, and the dissection flap is visible in the dilated aorta.
not fully explored. Coronary sinus cannulation for retrograde cardioplegia was attempted through the right-sided atrial chamber, but the blood evidently was well oxygenated and the coronary sinus orifice could not be located with certainty. Therefore, further efforts at coronary sinus cannulation were abandoned. After opening the aortic root, the intimal tear was identified just above the sinotubular junction. The aortic valve leaflets were morphologically normal, but the positions were reversed with the noncoronary cusp placed anteriorly. A valve-sparing root replacement with coronary reimplantation was performed. The cross-clamp time was 249 minutes followed by multiple repeated episodes of ventricular fibrillation treated with electric and pharmacologic methods until the eventual return of sinus rhythm. Weaning from CPB was gradual, with the requirement of multiple, high-dose inotropes. The total CPB time was 347 minutes. The systemic right ventricular ejection fraction was estimated to be ⬍10% on TEE after CPB, and after an episode of near-cardiac standstill requiring internal cardiac massage, an intraaortic balloon pump was placed via the right common femoral artery with some improvement. Hemostasis was achieved, but the sternum
Fig 2. The UE LAX view with CFD: severe aortic regurgitation was present secondary to dilation of the coronary sinuses and effacement of the sinotubular junction. (Color version of figure is available online.)
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Fig 3. The ME 4C view: the atrioventricular valves are associated with their appropriate ventricles, and the tricuspid valve is seen to be more apically placed than the mitral valve.
could not be closed because of hemodynamic instability from right ventricular compression. The sternum was stented open and the wound packed and sealed for transfer of the patient to the intensive care unit. Shortly after arrival in the intensive care unit, the patient arrested and, despite emergency sternal reopening and prolonged full resuscitative efforts, could not be revived. DISCUSSION
d-TGA is the most common cause of cyanotic CHD.1,2,7 Associated lesions may include a ventriculoseptal defect, pulmonary outflow tract obstruction, and, less commonly, coarctation of the aorta.1,7 Simple d-TGA is defined as situs solitus with atrioventricular concordance and ventriculoarterial discordant connections.5 The aorta arises from a right-sided, morphologic right ventricle and lies anterior and parallel to the pulmonary artery, which itself arises from a left-sided, morphologic left ventricle.7 Without palliation and subsequent correction, 50% will die within the first month of life and 89% in their first year.2 Historically, newborns with insufficient or no communica-
Fig 4. The transgastric short-axis view: heavy trabeculation confirmed that the hypertrophied and enlarged ventricle to the right of the interventricular septum was the right ventricle.
ACUTE ASCENDING AORTA DISSECTION
Fig 5. The ME 4C view with CFD: blood from the right-sided atrial chamber enters the right ventricle through the tricuspid valve and blood from the left-sided atrial chamber enters the left ventricle through the mitral valve. The presence of the baffle was unrecognized. (Color version of figure is available online.)
tion between the systemic and pulmonary circulations initially required a percutaneous Rashkind balloon atrial septostomy or a Blalock-Hanlon surgical atrial septectomy to improve oxygenation until a corrective procedure could be performed.7 Corrective but palliative surgeries during the 1960s (the Senning procedure) and the 1970s (the Mustard procedure) for d-TGA in infants who reached a reasonable size after atrial septostomy are known as atrial switch procedures. These procedures involved directing the systemic venous return to the left ventricle and pulmonary venous return to the right ventricle through an atrial baffle to restore normal physiologic blood flow.8,9 In the mid-1970s, it was recognized that atrial switch procedures were complicated by early right ventricular failure and tricuspid valve insufficiency because of the limitations of the right ventricle to function permanently as a systemic ventricle. The Jatene procedure was described to perform a definitive arterial switch procedure in the first 2 weeks of life to restore the normal anatomic arrangement of the aorta from the left ventricle and the pulmonary artery from the right ventricle.10 This is now the currently preferred surgery if the d-TGA anatomy is appropriate. The long-term outcomes after atrial switch procedures for d-TGA have been well documented for up to 3 decades.4-6 Survival of 80% at 28 years has been reported in patients with a Mustard atrial baffle procedure for simple d-TGA.5 The course of survival after atrial switch procedures may be complicated by the loss of sinus node function, atrial rhythm disturbances, tricuspid regurgitation, eventual right ventricular dysfunction, right ventricular failure, and late sudden death.46,11 Surgical complications include venous (both systemic and pulmonary) obstruction and baffle obstruction, or leak.11 Regular surveillance is indicated at specialized centers for timely interventions including surgery, medical therapy, pacemaker or automatic implantable cardioversion device implantation.6,7,12 In patients in whom right ventricular function is deteriorating, cardiac transplantation may be required.7,12 Specifically, patients with atrial switch procedures require fol-
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low-up with magnetic resonance imaging, which provides better information than transthoracic echocardiography (TTE) of right ventricular function and venous pathways.5,6 Magnetic resonance imaging is also more likely to detect dilation of the anteriorly placed ascending aorta, which may be missed on surveillance with TTE alone. Aortic dissection has not been described previously in longterm outcome studies of atrial switch procedures for d-TGA.1-6 Aortic dilation and dissection normally would not be associated with d-TGA unless the aortic valve was bicuspid or incompetent, but interest in the structural and functional integrity of the great arterial walls recently has focused on histologic examination of their specific medial constituents.13-15 Great arteries in CHD may dilate out of proportion to hemodynamic or morphogenetic expectations, may become aneurysmal, or may rupture.15 In a descriptive study of structural abnormalities of great arterial walls in CHD, the media of the dilated ascending aorta above the bicuspid aortic valves was found to be consistently abnormal whether the valves were stenotic, incompetent, or functionally normal, and all paracoarctation aortic biopsies had medial abnormalities.15 Histologic medial abnormalities in normal-sized ascending aortas were also described in 8 neonates with d-TGA in the study. These abnormalities of the medial wall of the ascending aorta in patients with d-TGA may herald a late aneurysmal change of the ascending aorta.15,16 Pregnancy has been identified as an independent variable for the structural change of the aortic media, but the extent to which these changes normalize after delivery and whether gestational changes are additive to those described in female patients with CHD who have reached reproductive age are not known.15 In the presented case, intraoperative transesophageal echocardiographic examination specifically ruled out the presence of a bicuspid aortic valve, but with adequate depth settings in the UE LAX view, aortic dilation was obvious. In the patient’s subsequently retrieved available records to the year 2000, there was no comment on the progression of size, if any, of the ascending aorta. Trivialto-mild aortic valve regurgitation was documented on TTE only during the patient’s pregnancies before 1996. However, the last available reported TTE from 2000, when the patient was not pregnant, did document trivial aortic regurgitation without reference to aortic size. Aortic root aneurysm has been reported after the surveillance of a 30-year-old man who had undergone a Mustard procedure at 2 years of age.16 In that case, elective aortic valve–sparing surgery was performed successfully for an aortic root measuring 4.5 cm and progressive volume overload of the functional left ventricle with a slightly impaired ejection fraction. Valvesparing surgeries originally were described for aortic valve incompetence and aneurysm of the ascending aorta, but favorable long-term results have been achieved in patients with Marfan syndrome and acute aortic dissection.16 In 1975, it was reported that the term “transposition” used to describe a variety of relations of the great arteries was a nonspecific term and should be reserved to describe the situation in which both great arteries arise from separate morphologically inappropriate ventricles.17 The authors described 4 anomalous hearts in which the great arteries arose
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in an unusual fashion from morphologically appropriate ventricles but there was atrioventricular concordance. In 1 of the anomalies described as an anatomically corrected malposition, patients presented with a left-sided anterior aorta, which must be distinguished from the left-sided anterior aorta more frequently encountered in congenitally corrected transposition (CC-TGA). The identification of cardiac anatomy is based on the segmental morphologic analysis of the venoarterial sequence (ie, the determination of the visceroatrial situs and atrioventricular and ventriculoarterial connections).18 d-TGA is characterized by atrioventricular concordance and ventriculoarterial discordance, whereas CC-TGA is characterized by atrioventricular and ventriculoarterial discordance, the latter resulting in a physiologically normal flow of blood through the chambers. Cardiac situs is determined by the laterality of the atria to the interatrial septum, specifically, by the position of the morphologic right atrium; the normal condition is the morphologic right atrium to the right of the interatrial septum.18,19 The right atrium is recognized by a large, pyramidal appendage and confirmed by the presence of the great veins and coronary sinus.19 In the presented case, these specific features could not be readily appreciated on TEE, and the presence of adhesions and the institution of femoral-femoral bypass limited the confirmation of those features by direct surgical inspection. Specifically, the coronary sinus could not be located with certainty by the surgeon through the presumed right atrium, confounding the ability to confirm atrial situs. The left atrium is characterized by a tapered, tubular appendage and the presence of pulmonary veins.18,19 In the presented case, the small size and apparent compression of the left-sided atrial chamber were thought to be from distortion by the massively dilated aorta. The presence of an atrial baffle was not recognized to be the reason CFD showed the flow of blood across the tricuspid valve from a right-sided atrial chamber into the right ventricle and across the mitral valve from a left-sided atrial chamber into the left ventricle even though it had been
established that systemic venous return was being directed through the mitral valve to the left ventricle and to the pulmonary circulation. The patient was not known preoperatively to have had surgically corrected d-TGA, but, in hindsight, the working diagnosis of CC-TGA could not have been supported because of the normal anatomic position of the ventricles. The diagnosis of an anatomically corrected malposition also could not be supported because even if atrioventricular concordance had been confirmed there was ventriculoarterial discordance in keeping with transposition and not malposition as the reason for the leftsided anterior aorta. In these circumstances, the physiologically normal blood flow suggested at least a form of corrected transposition, and, in the absence of a misleading history of PFO closure, the diagnosis of an atrial switch procedure for d-TGA may have been made correctly. The presented case highlights several issues in the increasing population of patients with CHD, with or without operative interventions, surviving more than 3 decades. First, these patients require lifelong surveillance at centers with the necessary specialist services.12 Second, patients with a variety of forms of complex CHD, irrespective of whether they have had surgical intervention or not, have histologic abnormalities of the medial constituents of the arterial walls and are at an increased risk for aortic abnormalities predisposing to dilation, aneurysm, rupture, and, as presented in this case, dissection.13,15,16 Third, patients with CHD can present with acute life-threatening conditions to any cardiac surgical unit, and, if appropriate information or expertise is not immediately available, a systematic approach to the application of the fundamental principles of the identification of cardiac anatomy using TEE should be adopted.11,18,19 ACKNOWLEDGMENT The author thanks Dr Kirsten Finucane, ONZM, Chief Surgeon of the Paediatric and Congenital Cardiac Service at Starship Hospital, Auckland, New Zealand.
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