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Print version ISSN 0034-7094
Rev. Bras. Anestesiol. vol.57 no.5 Campinas Sept./Oct. 2007
Anesthesia for repair of tetralogy of Fallot in an adult patient. Case report*
Anestesia para corrección de tetralogía de Fallot en paciente adulto. Relato de caso
Michelle Nacur Lorentz, TSAI; Bayard Gontijo FilhoII
do Hospital Biocor
IICirurgião Cardiovascular do Hospital Biocor
BACKGROUND AND OBJECTIVES: Congenital cardiopathy is one of the most
common problems at birth, with an incidence of 1 to 1.5 in 10,000 live births.
Currently, more than 85% of children with congenital cardiopathy survive to
adulthood, partly due to the development of new therapies, but especially because
of the tendency for earlier surgical corrections. On the other hand, adult patients
with non-corrected tetralogy of Fallot (TOF) are hard to find. The objective
of the present report was to describe a case of repair of TOF in an adult patient.
CASE REPORT: A female patient, 45 years old, with TOF, was admitted for surgical repair of her condition. Physical exam revealed extremities with cyanosis and oxygen saturation (SpO2) of 73%. General balanced anesthesia consisted of ethomidate, fentanyl, pancuronium and sevoflurane. During the surgery, the ventricular communication was closed, placement of a 24 French prosthetic conduit with valve and, posteriorly, the ventricular septum was fenestrated. Milrinone and dopamine were administrated when extracorporeal circulation (ECC) was removed. At the end of the surgery SpO2 was 97%. After the procedure the patient was admitted to the ICU where she remained for 72 hours, being discharged from the hospital on the eighth postoperative day in good condition.
CONCLUSIONS: This case illustrated the successful surgical repair in a high-risk patient, with a very good interaction among the surgeon, anesthetist, and intensive care.
Key Words: ANESTHESIA, Cardiac; DISEASES, Cardiac: congenital, tetralogy of Fallot.
JUSTIFICATIVA Y OBJETIVOS: La cardiopatía congénita es
uno de los problemas más comunes en el nacimiento acometiendo de 1 a
1,5 en cada 10.000 nacidos vivos. Actualmente más del 85% de los niños
con cardiopatías congénitas llegan a la fase adulta en parte debido
a los nuevos tratamientos, pero principalmente a la tendencia de hacer correcciones
quirúrgicas más precoces. Por otro lado es raro que se encuentre
un adulto con Tetralogía de Fallot no corregida. El objetivo del presente
relato fue describir un caso de T4F sometido a la corrección quirúrgica
en la edad adulta.
RELATO DEL CASO: Paciente de 45 años, sexo femenino, portadora de T4F internada para realización de corrección quirúrgica. Al momento del examen físico se presentaba cianótica en las extremidades y con saturación de oxígeno (SpO2) de 73%. Fue realizada anestesia general balanceada con etomidato, fentanil, pancuronio y sevoflurano. La corrección quirúrgica realizada fue el cierre de la comunicación ventricular e interposición de conducto con válvula pulmonar n° 24, posteriormente fue abierto el septo ventricular. A la salida de circulación extracorpórea (CEC) se administraron milrinona y dopamina. La SpO2 al concluir la operación era del 97%. Después del procedimiento quirúrgico la paciente fue llevada al CTI donde permaneció por 72 horas y tuvo alta en el octavo día postoperatorio en buenas condiciones.
CONCLUSIONES: El caso ilustró un éxito de la intervención quirúrgica en paciente de alto riesgo con gran interacción entre cirujano, anestesista y terapia intensiva.
The number of adults with congenital cardiopathies has increased considerably over the years, mainly due to improvements in surgical techniques and intensive care and the tendency for the early repair of said conditions. It is hoped that the day will come when the number of adults with congenital cardiopathies will be greater that that of children 1; however, it is difficult to estimate the prevalence of congenital cardiopathies in adults. The increase in the number of women in childbearing age with congenital cardiopathies, repaired or not, who decided to take the risk of a pregnancy has also increased. Some cardiopathies do well during the pregnancy, while others develop dangerous complications; the presence of cyanosis is associated with hemodynamic deterioration in more than half of pregnant women and, among non-cyanotic patients, only 15% present deterioration of their clinical condition. Therefore, the knowledge of the pathophysiology of congenital cardiopathies in adults is very important, since there are specific anesthetic implications. There are three groups of adult patients with congenital cardiopathies: those who underwent corrective surgeries, patients who had palliative procedures, and the ones that were not operated 2. There are several reasons why a patient reaches adulthood without having surgical repair of his/her disease: late diagnosis; patients with an equilibrium between pulmonary and systemic circulations, which is very common in complex cardiopathies that remain asymptomatic for a long time before developing an imbalance between the pulmonary and systemic circulation; some patients are deemed inoperable; and others are from areas in which the surgical intervention is not viable 1. The group of patients whose cardiopathies were not repaired is singular because of the long-term effects of hypoxia and excessive reduction in pulmonary blood flow on their physiology. Risk factors associated with intraoperative complications include the presence of cyanosis, treatment of congestive heart failure, deterioration in physical condition, and young 3.
A female patient, 45 years old, weighing 49 kg, presented with non-corrected tetralogy of Fallot. The congenital cardiopathy was diagnosed by her pediatrician in the first year of life, but her mother refused to have it repaired. When the patient reached adulthood, she also refused surgical repair. Sixteen years before admission, the patient underwent a cesarean section under general anesthesia; during the procedure she developed cardiac arrest, and remained in induced coma for two months in the intensive care unit. Twelve years before admission, she underwent exclusion of collaterals and was started on propranolol but, for personal reasons, did not continue the cardiological follow-up. Lately, her condition had been worsening, with progressive dyspnea, orthopnea, and paroxysmal nocturnal dyspnea. Four days before admission, the patient developed ascites and edema of the lower limbs, being admitted to the hospital with decompensated heart failure and atrial fibrillation (AF) with high ventricular rate. She was treated to improve her clinical condition and was referred for surgical repair. Echocardiogram showed malaligned interventricular communication (IVC), moderate atrial hypertrophy, important right ventricular hypertrophy (RV) with preserved contractile function; mild aortic, mitral, and tricuspid insufficiency; moderate aortic dilation and small pericardial effusion; preserved left ventricular (LV) systolic function and RV/PT gradient of 90 mmHg.
Preoperatively, the patient was taking furosemide, captopril, and propranolol. Physical exam revealed a Levine grade III mitral systolic murmur radiating to the axilla and tricuspid focus; heart rate (HR) = 78 bpm, with AF; blood pressure (BP) 140x80 mmHg. Pulmonary auscultation revealed fine bilateral basal crepitation.
Arterial blood gases revealed pH = 7.48, pCO2 = 25.3, pO2 = 47, HCO3 = 18.6, BE = 1.1. Oxygen saturation 78%, hematocrit (HT) = 52%, and hemoglobin = 17.8 g.dL-1; BUN = 42; creatinine = 0.6, and normal blood clotting parameters.
Monitoring included electrocardiogram, pulse oximetry, capnograph, intra-arterial blood pressure in the left radial artery with a 20G catheter, a 16G central venous catheter in the right subclavian vein, and a 16G peripheral vein catheter. A pulmonary artery catheter (16G) was introduced with direct supervision of the surgeon during the surgical procedure. Serial activated clotting time (ACT), ionogram, complete blood count, glucose level, and arterial blood gases were done.
Anesthetic induction was done with 0.3 mg.kg-1 of ethomidate, 10 µg.kg-1 of fentanyl, and 0.08 mg.kg-1 of pancuronium; 1% sevoflurane and additional doses of fentanyl, for a total of 40 µg.kg-1, were used for maintenance. Approximately 10 minutes before ECC, 735 mg of methylprednisoline (15 mg.kg-1) was administered. During ECC, 10 mg of midazolam and 4 g of pancuronium were administered. After administration of the test doses, three doses of aprotinin, 1,000,000 KIU, were administered before inducing anesthesia, and during and after ECC (3,000,000 KIU).
Surgical procedure consisted of closure of the IVC with a patch and placement of a 24 French prosthetic conduit with valve, besides fenestration of the ventricular septum to decompress the RV. Extracorporeal circulation lasted 110 minute, and the aorta was clampped for 75 minutes.
During warming up of the patient and after opening of the aorta, milrinone (0.5 µg.kg-1.min-1), without a loading dose, and dopamine (7 µg.kg-1.min-1) were instituted.
After removing the patient from ECC, the contractility of the heart was adequate (low pulmonary pressure) and SpO2 was 97%. The final hematocrit was 36%, mean arterial pressure (MAP) 70 mmHg, pulmonary artery pressure (PAP) 20 mmHg, and heart rate 88 with AF. Patient was hemodynamically stable when she was transferred to the ICU.
The patient was discharged from the ICU on the third postoperative day and from the hospital on the eighth postoperative day in good clinical condition.
Tetralogy of Fallot is the most common cyanotic congenital cardiopathy, being responsible for 10% of all congenital cardiopathies. It has an incidence of 14% among patients who grew-up with non-corrected congenital cardiopathies, being surpassed only by atrial and ventricular septal defects. Although, traditionally, four defects are describe as part of this cardiopathy: non-restrictive interventricular septal defect, obstruction of the outflow tract of the RV, right ventricular hypertrophy, and biventricular origin of the aortic valve, in reality tetralogy of Fallot encompasses a wide spectrum of disorders, from patients with interventricular septal defect and discrete pulmonary stenosis to pulmonary atresia. If it is not repaired, 70% of the children with this disorder die before the age of 10, but survival to adulthood is possible 4, although after the age of 40, the rate of survival is about 3%. Makaryus reported the case of a 52-year old patient who survived without repair 5. Obstruction of the outflow tract of the RV usually is infundibular, although it may also be valvar or supravalvar. In children, the infundibular obstruction is labile, leading to the characteristic crisis of hypoxemia (Tet spells), but adults whose TOF was not repaired usually do not experience those episodes. Cyanosis usually is secondary to inadequate pulmonary blood flow, often associated with a right to left shunt, and elevated hematocrit. In patients with limited pulmonary perfusion, one should avoid dehydration, maintain adequate systemic vascular resistance (SVR), control pulmonary vascular resistance, and minimize oxygen consumption. Hypoxemia causes hematologic changes, such as polycythemia, which is a compensatory response to increase oxygen transportation. Blood viscosity is increased, elevating the risk of thrombosis. Despite the risk of thrombosis, platelet count is usually decreased and, even when it is normal, its function is reduced, causing an increased risk of intraoperative bleeding. Chronic hypoxemia causes myocardial dysfunction, with reduced diastolic complacency and cardiac reserve. The limitation in cardiac output might not be evident at rest; however, affected patients characteristically have a low exercise tolerance. Chronic renal hypoxemia usually causes changes in the glomeruli6, associated with a reduction in glomerular filtration rate and increased levels of BUN and creatinine, which were not present in the patient presented here. Optimization of the cardiovascular system, with large volumes of fluids, should be done very carefully because it can be disastrous in patients with severe ventricular dysfunction; besides, ventricles used to work with pressure overload do not tolerate well an increase in volume; on the other hand, liquid restriction should not be exaggerated in patients with tetralogy of Fallot, which might lead to hypovolemia, dehydration with reduction in post-load, which causes an increase in the right to left shunt. The condition of the patient can be aggravated by thromboembolic phenomena in the presence of elevated hematocrit.
Traditionally, the surgical approach to these patients included a systemic-pulmonary anastomosis in the first months of life, and definitive repair between the ages of 2 and 5; however, the current tendency is to perform the definitive surgical repair earlier, to avoid problems caused by chronic hypoxemia, RV dysfunction, or even problems regarding the arterial shunt. Complete repair can be done in the infancy 7, with low mortality and associated with good long-term prognosis. However, some patients with congenital cardiopathy will undergo surgical repair at a later time. Most adult patients who underwent repair of tetralogy of Fallot were asymptomatic. Among patients undergoing surgical repair, 85% survive up to 36 years after repair 8; left ventricular function is normal 24 hours after the repair 9. Most problems associated with late surgical repair are associated with ventricular arrhythmias, exercise intolerance and sudden death secondary to chronic pulmonary regurgitation.
In the adult patient without surgical repair, one should expect an abnormal response to physical exercise 10, progressive hypertrophy of myocardial cells in 29.3% of cyanotic patients with tetralogy Fallot between the ages of 4 and 15 years, and in 81.1% of patients above 15 years with right ventricular systolic dysfunction and low cardiac output 11. Changes are more pronounced in older patients due to long-term cyanosis and pressure overload, increasing the probability of myocardial dysfunction and arrhythmias. The number of adult patients who survive with congenital cardiopathies has increased over the years. In the center of congenital cardiopathy in Toronto, 528 patients underwent cardiac surgery between 1992 and 2001 12. The main physiological changes to be considered in those patients are arrhythmias, hypoxemia, hyperviscosity, endocarditis, and coagulation abnormalities. The proper approach to the hyperviscosity syndrome includes avoidance of further deterioration in the condition of the patient, since repeated admissions to the hospital to bleed adult patients with congenital cardiopathy are frequent13. Recent studies on the repair of congenital cardiopathies in adults have been published. Erdoan et al. demonstrated a mortality rate of 3.1% after correction of tetralogy of Falllot in teenagers and adults, and that surgical repair can be successfully done in those patients 14. Lu et al. also had satisfactory results after definitive surgical repair of tetralogy of Fallot in adults 15, with an in-hospital mortality rate of 7% and a 5.7% late mortality rate, demonstrating that the greater benefit of surgical repair in adults is functional improvement.
In some patients with a good response to palliative surgery and those who had no surgery and did not develop late deterioration, conventional anesthetic management was successful. The anesthetic technique in patients with cardiac deterioration and functional limitations should be evaluated carefully. The most important aspects regarding preoperative care is the detailed knowledge of the pathophysiology of the disease, functional state, and long-term changes that the uncorrected congenital cardiopathy caused in the patient. The entire team should be involved and the anesthesiologist should anticipate the intraoperative problems that might ensue.
Administration of pre-anesthetic medication to reduce oxygen consumption should be done carefully, due to the risk of respiratory depression in patients with cyanotic cardiopathy and, since the patient described here had cardiovascular decompensation, pre-anesthetic medication was not administered. All intravenous anesthetics can be safely used for induction, because proportion and dose are more important than the type of drug chosen. Anesthetic induction varies according to the experience of the anesthesiologist, degree of patient cooperation, and hemodynamic parameters. Inhalational induction with sevoflurane is usually well-tolerated in children; intramuscular ketamine can also be used in these patients. In adults, induction is usually done with intravenous drugs, and one should not forget that all drugs used for induction, except for ketamine, are associated with reduction in systemic vascular resistance. Induction with intravenous drugs should be done slow and carefully, because circulatory effects occur rapidly. Inhalational induction is usually more prolonged, but it is rarely a problem 16. In cases with simple cardiac lesions, halothane, isoflurane, or sevoflurane do not change the degree of left-to-right shunt in patients ventilated with 100% oxygen 17. However, this cannot be extrapolated to patients with complex congenital cardiopathy or for those with right-to-left shunt. The need of invasive monitoring depends both on the type of surgical repair and cardiac lesion. One should remember that in the presence of a right-to-left shunt, measurement of cardiac output by thermodilution on the right side of the circulation might not be accurate. Capnography greatly underestimates PaCO2 and the degree of discrepancy is correlated with the degree of right-to-left shunt. Transesophageal echocardiogram allows the evaluation, during surgery, of ventricular function, preload, and intracardiac shunt, as well as valvar function. Pulse oximetry also loses its accuracy in patients with severe hypoxemia. Extreme care should be taken with the presence of air in intravenous lines, because it can reach the central nervous system directly through the right-to-left shunt.
Methylprednisolone was administered before ECC to decrease systemic inflammatory response 18; besides, a study by Prasongsukarn et al. demonstrated that the administration of corticosteroids before ECC decreases the frequency of postoperative AF 19. Aprotinin has been widely used in cardiac surgeries because it decreases bleeding and the need for blood transfusions 20. Aprotinin reduces fibrinolysis significantly and improves hemostasis in cardiac surgeries, and it also interferes with other clotting factors, generating a hemostatic balance. Other benefits of this drug include its anti-inflammatory properties that could help reduce systemic inflammatory response secondary to the noxious effects of ECC and the microvascular inflammatory response secondary to cardiac surgery with or without ECC. It is known that a multimodal treatment should be used to prevent the systemic inflammatory response 21.
As for the inotropic agents used, in the presence of ventricular hypertrophy secondary to long-term pressure overload and cardiac decompensation of this patient, worsening of myocardial dysfunction after anatomical repair was a real possibility and, therefore, the administration of inotropic agents was iniated before taking the patient off ECC. Doses of dopamine from 3 to 10 µg.kg-1.min-1 have inotropic action, being adequate for patients with tetralogy of Fallot; one should avoid doses higher than 15 µg.kg-1.min-1, because of the marked increase in vasoconstrictive and chronotropic properties. It is known that smaller doses of dopamine do not protect renal function and, therefore, they should not be used 22,23. The probability that AF was caused by dopamine was ruled out based on the low dose administered to the patient and the fact that she already had this arrhythmia upon admission to the hospital. Milrinone was added based on the fact that, in congenital cardiopathy in adults, one should worry about the development of tachycardia, increase in end-diastolic pressure, post-load, and oxygen consumption, since they are not tolerated in adults as well as in children. In the case presented here, we were aware that the development of arrhythmias should be avoided. Milrinone is a non-glycoside, non-catecholamine drug, with vasodilator, inotropic, and lusitropic properties, and has been widely used in adults with congestive heart disease with good results24. In the present case, one could question whether the association of epinephrine and milrinone would have been better, since they have synergistic action, being a good treatment option both in adults and children after surgery.
In conclusion, the knowledge of the pathophysiology of the adult patient with congenital cardiopathy is vital, and the decisions of a multidisciplinary team and individualized patient management contribute to the success of the surgery.
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Dra. Michelle Nacur Lorentz
Rua Marquês de Maricá, 181/1502 Santo Antônio
30350-070 Belo Horizonte, MG
Submitted em 30 de maio de 2006
Accepted para publicação em 21 de junho de 2007
* Received from Instituto Biocor, Nova Lima, MG