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On-line version ISSN 1806-907X
Rev. Bras. Anestesiol. vol.55 no.1 Campinas Jan./Feb. 2005
Labour analgesia in parturient with uncorrected tetralogy of Fallot. Case report*
Analgesia de parto en paciente con tetralogía de Fallot no corregida. Relato de caso
Florentino Fernandes Mendes, TSA, M.D.I; Carlos Alberto T Farias, M.D.II; Daniel Segabinazzi, M.D.III
IChefe do Serviço de Anestesiologia
da Santa Casa de Porto Alegre. Mestre em Farmacologia pela FFFCMPA. Doutor em
Medicina pela FCMSCSP
IIMédico do Serviço de Anestesiologia da Santa Casa de Porto Alegre. Médico Anestesiologista do Grupo Hospitalar Conceição
IIIME2 do CET/SBA da FFFCMPA
BACKGROUND AND OBJECTIVES: Although tetralogy
of Fallot is the most common cyanotic congenital heart disease, national publications
correlating this condition with anesthetic practice are scarce. This report
aimed at presenting a case of labor epidural analgesia in a patient with uncorrected
tetralogy of Fallot diagnosed during gestation.
CASE REPORT: Patient 26 years old, 1.54 m, 56 kg, 32 weeks and 5 days of gestational age, who had been diagnosed with tetralogy of Fallot during gestation. Patient was admitted in labour. After obstetric evaluation and decision for natural birth, epidural analgesia was performed with 0.125% bupivacaine associated to 100µg fentanyl through a catheter. Patient gave birth 1 hour and 30 minutes after the procedure. The newborn weighed 1485 grams and had an Apgar score of 6 and 8 at one and five minutes, respectively. Patient remained stable, with no hemodynamic or ECG changes.
CONCLUSIONS: Selecting the appropriate anesthetic technique is extremely important when managing patients with uncorrected tetralogy of Fallot. Favorable uterine dynamics and cervical conditions, particularly in patients with no history of syncope, are critical findings for adequate labour analgesia indication.
Key words: ANALGESIA, Labour; ANESTHETIC TECHNIQUES: Regional: epidural continuous; DISEASES, Cardiac: tetralogy of Fallot
JUSTIFICATIVA Y OBJETIVOS: Aunque la tetralogía
de Fallot sea la más común de las cardiopatías congénitas
cianóticas, las publicaciones nacionales, relacionando esa enfermedad con
la práctica anestésica son escasas. El objetivo de este relato es
presentar un caso de analgesia de parto en paciente portadora de tetralogía
de Fallot no corregida y diagnosticada durante la gestación.
RELATO DEL CASO: Paciente con 26 años, 56 kg, 1,56 m, edad gestacional 32 semanas y 5 días, con diagnóstico de tetralogía de Fallot realizado durante la gestación. Internó en trabajo de parto. La conducta obstétrica fue la de parto vía baja, siendo realizada analgesia de parto a través de bloqueo peridural con bupivacaína a 0,125% y fentanil (100 µg) y colocación de catéter peridural. Después de 1h30 minutos del inicio de la analgesia, ocurrió el nacimiento. El peso del recién nacido fue 1485 g y el índice de Apgar 6 y 8 en el primero y en el quinto minutos, respectivamente. La paciente permaneció estable y sin alteraciones hemodinámicas y/o electrocardiográficas.
CONCLUSIONES: La elección de la técnica anestésica es de fundamental importancia en el manoseo de las pacientes con tetralogía de Fallot no corregidas. Condiciones favorables del cuello y buena dinámica uterina, particularmente en aquellas pacientes sin historia de síncope, se vuelven imprescindibles para una buena indicación de la analgesia de parto.
Tetralogy of Fallot is a cyanotic congenital heart disease characterized by right ventricular outflow obstruction, right ventricular hypertrophy, interventricular septum defect and variable aortic transposition 1,2. The obstruction of right ventricular outlet is due to infundibular stenosis in many patients. At least 20% to 50% of patients also present pulmonary valve stenosis and a low percentage has some supravalvar stenotic element. Infundibular obstruction is increased in situations of increased sympathetic tone (dynamic variable) and is probably responsible for cyanosis observed in several young patients 3.
The combination of right ventricular outlet obstruction and interventricular communication (IVC) results in the ejection of right ventricular non-oxygenated blood and aortic oxygenated blood. Right-left shunt determines the level of hypoxemia and, as a consequence, the severity of the disease, which varies as a function of fixed components: right ventricular obstruction level, aortic dextroposition level, IVC size - as well as variable components: systemic vascular resistance (SVR), pulmonary vascular resistance (PVR), infundibular obstruction, venous return and myocardial contractility 4. Events with increased PVR, such as acidosis and increased airway pressure, should be avoided 5.
The maintenance of variable components is critical for anesthetic management of patients with uncorrected disease, since they are major determinants of their hemodynamic balance.
This report aimed at describing a case of labour analgesia in uncorrected tetralogy of Fallot patient diagnosed during gestation, and at listing the cares for anesthetic management of this disease.
Patient 26 years old, 56 kg, 1.56 m, 32 weeks and 5 days of gestational age, in labor, with uterine dynamics of 3 contractions in 10 minutes and with 4 cm cervical dilatation. Prenatal evaluation has revealed severe heart murmur and patient was referred to a specialized hospital were tetralogy of Fallot was diagnosed. Patient denied having previous knowledge about the disease. Patient referred mild dyspnea and cyanosis of extremities, which have worsened along gestation and were associated to not disabling precordial pain at moderate effort.
At preanesthetic evaluation patient presented with central and extremities cyanosis and clubbed fingers, denying allergies, previous surgeries and use of medications. Fetal cardiotocography and echocardiography were normal.
Maternal echocardiography, performed at 27 weeks of gestation has revealed levocardia, aortic arch to the left, agreeing and normal AV connection, agreeing ventricular-arterial connection and normal connection mode. Patient had broad subaortic IVC as associated defect, which caused interventricular septum anterior and superior deviation, suggesting tetralogy of Fallot. Ventricles and atria had normal size, thickness and movement. ECG showed antero-septal T wave inversion.
After obstetric evaluation and decision for natural birth, monitoring consisted of pulse oximetry varying from 89% to 78% according to presence or absence of uterine dynamics, ECG with regular rhythm and T wave inversion, and noninvasive blood pressure with mean level of 120/60 mmHg. Pain scores were monitored with visual analog scale.
Anesthetic technique was epidural block performed at L2-L3 with patient in the sitting position and using 16G Tuohy needle. After a test dose with 3 mL of 2% lidocaine with vasoconstrictor, 8 mL of 0.125% bupivacaine (10 mg) and fentanyl (100 µg) were injected and epidural catheter was inserted 5 cm into the epidural space. Patient remained monitored and receiving 2 L.min-1 oxygen via nasal catheter.
Patient referred pain relief approximately 5 minutes after blockade with minor uterine dynamics change. After 30 minutes patient presented 9 cm cervical dilatation and mild to moderate perineal pain during contractions. Pressure levels were not changed. Oximetry continued oscillating during contractions from 88% to 80%. With one hour of analgesia patient presented 10 cm cervical dilatation and started to have more effective contractions. Pain scores increased and 6.25 mg of 0.125% bupivacaine were injected through the epidural catheter.
Patient was placed in the gynecological position and oriented not to push during contractions when oximetry levels were 76% to 78%. Patient gave birth 1h30m after analgesia. Newborn weight was 1486 g and Apgar score at one and five minutes was 6 and 8, respectively.
After delivery patient remained stable, with no hemodynamic or ECG changes, however with increased oximetry levels of 91% to 93%.
A new echography was performed the next day aiming at finding right ventricular outflow which, together with previously detected changes, has evidenced right ventricular hypertrophy, lack of IAC, IVC with broad outflow, anterior infundibular septum shift generating moderate obstruction and normal AV valves with normal ejection fraction. Pulmonary valve was hypoplastic and stenotic and aortic valve was ectatic with aortic 50% riding. Pulmonary arteries seemed to be unobstructed and confluent. Coronary arteries were not adequately reviewed. Test conclusion was: results compatible with tetralogy of Fallot.
Tetralogy of Fallot is a congenital heart disease characterized by ventricular septum defect, pulmonar stenosis, aortic riding on interventricular communication and right ventricular hypertrophy. This disease represents 15% of congenital cardiopathies and is the most common among cyanotic heart diseases. Approximately 15% of tetralogy of Fallot patients have a deletion of the short arm of chromosome 22 as the genetic cause of the disease and there is 50% probability of transmission to offsprings 1,2,6,7.
Disease pathophysiology depends on the level of right ventricular outflow obstruction. With relatively mild obstruction, presentation is increased pulmonary blood flow (also called Rose Tetralogy or acyanotic Fallot). Occasionally this is the adult presentation 8,9. Most children, however, have significant right ventricular outflow obstruction with consequent right-left shunt and cyanosis.
Gestation increases mortality and morbidity rates of uncorrected tetralogy of Fallot patients, especially those with history of syncope, polycythemia and right ventricular hypertrophy, what is not true for those surgically corrected 1,3,8.
Risk is increased when arterial oxygen saturation levels at rest are below 85%. Decreased systemic vascular resistance during gestation and labour may increase shunt and worsen acidosis.
The level of hypoxemia is a direct function of shunt severity and magnitude, which depend on fixed factors -right ventricular obstruction level, aortic dextroposition level, IVC size - and variable factors - SVR and PVR, infundibular obstruction, venous return and myocardial contractility 4.
The indication of the anesthetic technique for uncorrected tetralogy of Fallot patients, as well the adequate management of possible intraoperative events, are based on the understanding of the severity of the disease to determine major shunt mechanism. Anesthetic drugs and techniques may significantly change variable components determining the hemodynamic balance of such patients 1,2.
Regional techniques may affect this balance according to the level of sympathetic blockade, which may increase shunt by decreasing SVR and, as a consequence, decrease ventricular filling and cardiac output 2,5.
Basic obstetric anesthesia principles should be particularly applied to these patients: adequate analgesia, maintenance of uterine-placental perfusion preventing aortocaval compression and minimization of sympathetic block by maintaining intravascular volume. Intravenous fluids should be carefully monitored to prevent deficits or excesses, leading to shunt worsening and patients decompensation 2.
The choice of the anesthetic technique is critical to manage tetralogy of Fallot patients. When pain may be relieved with minor hemodynamic changes, as it is the case with labour epidural analgesia and low local anesthetics concentrations, this would be valuable for the management of these patients.
Combined labour analgesia is also effective and safe because it allows the use of subarachnoid lipophylic opioids, such as sufentanil, leading to faster analgesic effect, lower sympathetic and motor block, in addition to lower local anesthetics via epidural catheter10-12.
However, physiological and obstetric conditions have to be observed for good labour outcome. Favorable cervical conditions and good uterine dynamics in these patients, especially those with no history of syncope, are indispensable for adequate indication of labour analgesia.
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Dr. Carlos Alberto T. Farias
Address: Av. Arnaldo Bohrer, 184/23 Bairro Teresópolis
ZIP: 91720-130 City: Porto Alegre, Brazil
Submitted for publication October 3 de outubro
Accepted for publication September 27, 2004
* Received from Maternidade Mário Totta, Núcleo de Anestesia e Analgesia Obstétrica do Serviço de Anestesiologia da Santa Casa de Porto Alegre - CET/SBA FFFCMPA, Porto Alegre, RS