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J Thorac Cardiovasc Surg 1998;116:924-931
© 1998 Mosby, Inc.
SURGERY FOR CONGENITAL HEART DISEASE |
From the Divisions of Cardiology and Cardiothoracic Surgery, Children's Hospital of Philadelphia, and the Departments of Pediatrics and Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pa.
Read at the Seventy-eighth Annual Meeting of The American Association for Thoracic Surgery, Boston, Mass, May 3-6, 1998.
Received for publication May 8, 1998. Revisions requested June 18, 1998.Revisions received Aug 18, 1998. Accepted for publication Aug 18, 1998. Address for reprints: Jack Rychik, MD, Division of Cardiology, Children's Hospital of Philadelphia, 324 S 34th St, Philadelphia, PA 19104.
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Abstract |
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Introduction |
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TopAbstractIntroductionMethods and patientsResultsDiscussionAppendix: DiscussionReferences |
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A variety of surgical strategies are possible. Optimal repair involves recruitment of the RV for pulmonary perfusion and separation of the 2 circulations (biventricular repair). Patients with an adequate-sized tricuspid valve and RV, or those deemed to have the potential for growth to adequate size after promotion of antegrade flow, can undergo a biventricular repair by creating continuity between the RV and the main pulmonary artery.
1 Commonly, an aortopulmonary shunt is placed temporarily to secure adequate pulmonary perfusion. 2 When the RV is very small, a biventricular repair may not be feasible. If significant coronary stenoses or interruptions are present, then RV decompression may result in compromise of the coronary circulation and a biventricular repair is contraindicated. 3,4 A strategy directed toward single ventricle repair via a Fontan operation 5,6 or heart transplantation 7 are alternative treatment options.
Overall outcome for PA/IVS has been poor. In a study by the Congenital Heart Surgeons Society, survival to 4 years was only 64%. 8 RV dependency for coronary circulation was identified as an early risk factor. Presumably, a more selective approach to performance of a biventricular repair and use of either the single ventricle approach or heart transplantation may result in improved outcome. Recently, good outcome has been reported in patients who have undergone the Fontan operation for severe hypoplasia of the RV with or without significant coronary abnormalities. 5,6 The purpose of our study was to review our experience with PA/IVS and (1) to compare the outcome of patients with single ventricle approach with that of those with biventricular repair and (2) to compare the outcome of patients with coronary abnormalities with that of those with normal coronary arteries.
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Methods and patients |
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TopAbstractIntroductionMethods and patientsResultsDiscussionAppendix: DiscussionReferences |
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Strategy A: Single ventricle pathway (n = 31, 46%).
Patients treated by strategy A were considered not to be candidates for neonatal RV recruitment and had an aortopulmonary shunt alone as their initial source for pulmonary blood flow. One patient in this group had excision of the tricuspid valve and another had patch closure of the tricuspid valve simultaneous with placement of the shunt. 9
Strategy B: Biventricular repair pathway (n = 32, 48%).
Patients treated by strategy B were considered to have an appropriate-sized RV for recruitment and had an operation that included RV outflow tract reconstruction in infancy. All but 1 patient in this group had simultaneous creation of an accessory source of pulmonary blood flow (aortopulmonary shunt in 15; ductal infiltration with formalin in 16).
Strategy C: Transplant pathway (n = 4, 6%).
Patients treated by strategy C were considered to have serious coronary abnormalities prohibiting use of their native heart for reconstruction and underwent heart transplantation. The ductus arteriosus was kept patent via alprostadil (prostaglandin) infusion in 2 patients, and 2 had placement of an aortopulmonary shunt.
Decisions concerning initial surgical strategy were based on the clinical judgment of the attending cardiologist and surgeon using data obtained from echocardiography and angiography. Because of the time span of the study and evolution of understanding of this disease over the years, no uniform criteria were applied to each patient in determining which type of treatment strategy to undertake. Factors included subjective assessment of RV and tricuspid valve size, the presence of a tripartite RV, 10 and the severity of coronary involvement (ie, fistulas, stenoses, or interruptions).Although subjective judgment was used to evaluate for RV size at the time of management decision for each patient, we retrospectively reviewed the initial echocardiograms or angiogram to measure the tricuspid valve anulus diameter, as suggested by Hanley and associates. 8 Tricuspid valve Z-score (number of standard deviations of the diameter measurement from the expected mean for body surface area) was determined for each patient. Patients who underwent strategy A had on average a smaller tricuspid valve anulus than patients who underwent strategy B; however, overlap was present (mean Z-score –3.2 [2.5], range –7 to 1.5 vs mean Z-score –0.5 [1.6], range –4 to 1.5, P < .001). Patients who underwent strategy C had a similar tricuspid valve size to those who underwent strategy A (mean Z-score –3.3 [2.1], range –5 to –1).Coronary angiography was performed in infancy and data were available for review in 65 patients (97%). Patients were grouped on the basis of severity of coronary abnormalities: grade 0, no abnormalities (n = 37, 57%); grade 1, RV–coronary artery fistulas alone (n = 20, 31%); grade 2, RV–coronary artery fistulas and important stenoses/interruptions (RV-dependent coronary circulation) (n = 8, 12%). Smaller tricuspid valve size was noted in patients with more severe coronary abnormalities. Mean tricuspid valve Z-scores for coronary grades 0, 1, and 2 were –1.6 [2.4], –2.4 [2.3], and –3.2 [2.1], respectively.Of the 67 patients, 48 (72%) had a "definitive" repair at most recent follow-up, defined as (1) a 2-ventricle system with the RV supplying the pulmonary circulation with minimal or no shunt at atrial or arterial level, (2) a single ventricle system after a Fontan operation, (3) a superior vena cava–pulmonary connection with inferior vena caval return directed across the tricuspid valve and ejected into the pulmonary circulation via the RV and superior vena caval return channeled directly to the pulmonary arteries bypassing the RV (1 1/2-ventricle repair), 11 or (4) a heart transplantation. Additional procedures were performed before or at the time of the definitive repair (Table II). Survival curves were generated by means of the Kaplan-Meier method. The Cox proportional hazards regression was used to look for differences based on initial operative strategy and coronary anatomy. The t test was used to assess for differences in tricuspid valve Z-score between survivors and nonsurvivors.
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Results |
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Four patients had a hemi-Fontan or bidirectional Glenn shunt with 2 deaths. One had postoperative left ventricular (LV) dysfunction and died (coronary grade 1), and 1 died in a motor vehicle accident. Two survivors are presently awaiting the Fontan operation.
One patient had a Waterston shunt placed in infancy, was lost to follow-up, and appeared again with severe LV dysfunction at 19 years of age (coronary grade 0). The patient received a heart transplant but died of acute postoperative graft failure.
Strategy B: Biventricular repair pathway (n = 32).
Early mortality was high, with 8 patients (25%) not surviving beyond the initial operation (Fig 3). Two of these had a dilated RV and right atrium with severe dysplasia of the tricuspid valve, and 2 had evidence of aortic/subaortic stenosis with a gradient of more than 30 mm Hg on catheterization or Doppler echocardiography. No coronary abnormalities were present in these patients. Death occurred within 1 to 5 days of the operation. Another infant had normal coronary arteries, a bicuspid, stenotic aortic valve with a 50 mm Hg gradient on catheterization, and underwent a balloon dilation of the aortic valve. Progressive biventricular failure ensued and the infant received a heart transplant at 4 months of age but died of multisystem organ failure. Three infants died within 1 week of the operation of unexplained causes; 2 had coronary fistulas with no evidence for stenoses (coronary grade 1), and in 1 angiographic data were unavailable.
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Three patients were switched to a single ventricle approach. One had an initial pulmonary valvotomy with multiple aortopulmonary shunts placed early in life and was referred late to our institution with cyanosis and a small RV. A hemi-Fontan operation was performed at age 16 followed by a Fontan operation 6 months later. Another patient had poor growth of the RV and had a Fontan operation at 18 months of age. Another patient had poor growth of the RV, LV dysfunction (coronary grade 1), and underwent a hemi-Fontan operation followed by a Fontan operation 6 months later. LV dysfunction persisted and he underwent successful heart transplantation 5 months later.
Strategy C: Transplant pathway (n = 4).
Four patients had serious coronary abnormalities (grade 2) in infancy and were listed for heart transplantation (Fig 4). One infant had a cardiac arrest while awaiting transplantation and subsequently died early after receiving a heart transplant as a result of multisystem organ failure. The other is well from a cardiac standpoint 7 years after transplantation but has lymphoproliferative disease. The 2 patients who had placement of an aortopulmonary shunt were discharged to their homes and received transplants at 3 1/2 and 5 1/2 months of age, respectively. One was re-listed for transplantation because of development of severe mitral regurgitation, obtained a heart 11 months after the original transplant, and is doing well at 34 months of age. The other is doing well at 32 months of age.
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Discussion |
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TopAbstractIntroductionMethods and patientsResultsDiscussionAppendix: DiscussionReferences |
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12-14 In our series, biventricular repair was achieved in only one third of patients. None had RV-dependent coronary circulation and, similar to the findings of the Congenital Heart Surgeons Society study, all had a tricuspid valve Z-score greater than –4. 8 The application of single ventricle palliation or heart transplantation strategies allow for equivalent outcomes to be achieved even in patients with the risk factors of small RV size and coronary abnormality.
Although the primary disease is in the RV, it is the LV myocardium that is vulnerable to circulatory insufficiency and dysfunction. Ischemia can occur if decompression of the RV is attempted when a large portion of the myocardium is supplied by a hypertensive RV with coronary stenoses just proximal to the connecting site between the RV and coronary artery (RV-coronary dependency). 4 Even in the absence of proximal stenoses, when there is dual supply to the coronary arteries from both the RV and aorta, decompression of the RV may result in a "steal" of coronary blood into the RV, with diminished perfusion to areas distal to the connection. 3 Focal narrowing and diffuse hypoplasia of the coronary arteries distal to the connecting site to the RV have also been described, implying that a competitive source of coronary flow results in the development of an abnormal vascular tree downstream from the initial lesion. 15 Functional disturbances including abnormalities of LV regional wall motion, LV compliance, and systolic performance have been demonstrated even in patients with less severe coronary abnormalities. 16-18 Recent data support the view that histologic abnormalities of the LV are present in all patients with PA/IVS who do not have a normal-sized RV and completely normal coronary arteries. Akiba and Becker 19 found increased myocardial cell swelling and increased interfiber collagen content, reflecting chronic ischemia in unoperated specimens from patients with PA/IVS and no coronary stenoses. They concluded that these findings make the LV less tolerant of potential volume loads.
This observation may in part explain the high early mortality in this study; 63% of our deaths occurred within the first 2 weeks after initial palliation. Aortopulmonary shunt placement results in a volume load on the LV and a lowering of systemic diastolic pressure. The workload on the heart is increased while coronary perfusion is diminished in infants with a vulnerable myocardium. In particular, excessive pulmonary overcirculation may have been present in those with a formalin-infiltrated ductus because accurately constricting the ductus arteriosus can be difficult and imprecise. 20 In addition, severe coronary abnormalities may have been overlooked. Aortography and RV angiography were used to determine coronary anatomy; however, in the absence of selective coronary injections, a difficult and high-risk procedure in neonates, important stenoses may be missed.
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21 Hemodynamically significant anatomic obstruction to LV outflow was present in 3 other patients. Septal bowing and LV outflow obstruction after the Fontan operation has been described 22; however, the finding of significant aortic valve or fixed subaortic narrowing is unusual and not previously reported.
In our series, 7 patients underwent heart transplantation. Whether to use the strategy of heart replacement at the outset or to plan for a single ventricle approach in patients with RV-dependent coronary circulation is unclear. Some have argued that quantifying the degree of RV-coronary dependency is useful and that RV decompression can be successfully achieved if no more than 1 coronary vessel is involved. 4 As previously stated, accurately defining the precise coronary anatomy in a neonate can be difficult. Adequate myocardial perfusion in the presence of RV-coronary dependency, or even a fistulous connection alone with dual distal supply, does not guarantee continuing good perfusion over time. Shear forces from RV ejection into the coronary vessel may result in a progressive obliterative process at the site of connection. 15 In addition, until the time of separation of the circulations at the Fontan operation, the RV is ejecting desaturated blood into the coronary arteries, which may place the distal myocardium at risk for ischemia, in particular during periods of high demand. When deciding on a single ventricle strategy or heart replacement, one must weigh these concerns against the issues of organ availability, early graft failure, rejection, and coronary graft disease after heart transplantation. 7
To date, there is little data on the well-being of patients with severe coronary abnormalities after the Fontan operation. In our series, only 2 patients with RV-coronary dependency had a Fontan operation, and 1 is awaiting the Fontan operation, all without overt clinical evidence for myocardial ischemia. In addition, all 12 patients with fistulas alone between the RV and coronary arteries (grade 1) who survived beyond the Fontan procedure are doing well at a median of 56 months. Of note, none of these patients had thromboexclusion of the RV, as recommended by some, 23 and only 1 had excision of the tricuspid valve, which subsequently resulted in ischemia and an apical aneurysm of the LV. Whether myocardial insufficiency will develop over time is unclear. Sensitive methods for detecting progressive changes in myocardial perfusion such as thallium imaging studies or dobutamine-stress echocardiography may prove useful when used serially in these patients. 24,25 A combined approach involving the single ventricle strategy initially, with listing for heart transplantation at the early signs of myocardial insufficiency, may be the best approach. If the single ventricle approach is chosen, we recommend the placement of a small aortopulmonary shunt to limit pulmonary blood flow and the early performance of a superior vena cava–pulmonary connection to eliminate volume load and improve diastolic coronary filling. Early performance of the Fontan operation should also be considered to divert pulmonary venous return to the RV at the earliest opportunity, thereby allowing for fully saturated blood to be ejected into the coronary arteries.
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Appendix: Discussion |
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TopAbstractIntroductionMethods and patientsResultsDiscussionAppendix: DiscussionReferences |
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Second, after a patient receives a cavopulmonary shunt, do you have any echocardiographic or computed tomographic criteria to decide whether to attempt a Fontan repair, a partial biventricular repair, or 1 1/2-ventricle repairs?
My final question is this: In your large experience I failed to notice any patients with Ebstein's malformation of the tricuspid valve. In our experience these patients have a very poor prognosis. Have you treated such patients, and do you consider them candidates for transplants?
Dr Rychik. Thank you, Dr Reddy, for your comments. Regarding tricuspid valve size, the question frequently comes up as to whether one should stick with a strict regimen of using tricuspid valve Z-score versus using one subjective assessment of RV size. In my experience, and I think in the experience of others, there appears to be fairly good concordance between the two. Experienced surgeons and cardiologists are fairly good at determining when an RV is of adequate size and when it is not. As you mentioned, the Congenital Heart Surgeons Society used a cutoff of about –3 to –4, and our tricuspid valve Z-score when we looked back at this retrospectively fell into that same category. What is still not completely clear are some of the other variables that enter into the assessment subjectively as to whether an RV is of adequate size. Other authors have used the concept of the different parts of the RV, for example, whether the RV is tripartite with an infundibular sinus portion and trabecular zone.
At the moment we would still probably stick with a subjective assessment. We would evaluate the tricuspid valve diameter as part of the complete evaluation, looking at the different parts of the RV as well, to determine whether there was an infundibular outflow, sinus portion, or trabecular zone.
Your second question concerned our use of criteria to determine whether we should proceed to a biventricular repair or not. We take these patients to the catheterization laboratory and attempt to close or balloon occlude the atrial septum and assess for right atrial pressures and mixed venous saturation to estimate for cardiac output.Regarding the tricuspid valve, some patients clearly have Ebstein's anomaly of the tricuspid valve. At times it can be difficult to determine in that category of patients whether one is dealing with a functional pulmonary atresia or in fact anatomic atresia. That is a different category of patients from the 2 or 3 in this study who, by strict anatomic definition, did not seem to have Ebstein's anomaly. As an echocardiographer, I would describe Ebstein's anomaly as inferior and apical displacement of the septal leaf of the tricuspid valve with a long curtain-like anterior leaflet. These patients did not fall into that category. They had evidence for very thickened dysplastic-appearing tricuspid valves without displacement of the septal leaflet. Those patients have a primary tricuspid valve abnormality that results in poor anterograde flow prenatally and then results in pulmonary atresia; however, they may very well be a different group of patients. Physiologically, the RV in those patients is similar to that of the patients with Ebstein's anomaly. They have very poor potential for development of forward flow, and I think they should be considered for heart transplantation.
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Acknowledgments |
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References |
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TopAbstractIntroductionMethods and patientsResultsDiscussionAppendix: DiscussionReferences |
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