Anesthesia for blalock-taussig shunt and pacemaker placement in an adult patient with univentricular heart: case report

Abstracts

JUSTIFICATIVA E OBJETIVOS: O ventrículo único é uma cardiopatia complexa rara e grave, sem possibilidade de tratamento cirúrgico curativo, associada à alta mortalidade durante a primeira infância. O objetivo desse artigo foi descrever um caso raro de paciente adulto com ventrículo único não-operado que se internou para realização de valvoplastia pulmonar via hemodinâmica e acabou sendo submetido à cirurgia de Blalock-Taussig modificado e implante de marca-passo epicárdico. Teve como objetivo complementar chamar a atenção para as particularidades anestésicas do paciente adulto portador de cardiopatia congênita não-corrigida. RELATO DO CASO: Paciente de 34 anos, 60 kg, portadora de cardiopatia congênita complexa tipo ventrículo único, estenose infundibulovalvar pulmonar importante e hipertensão pulmonar moderada. Admitida no hospital sem condições de correção cirúrgica e com história pregressa de várias sangrias terapêuticas para tratamento de policitemia. Foi internada devido a piora da hipoxemia, um episódio de síncope e bloqueio atrioventricular total (BAVT) de início recente. À internação apresentava estabilidade hemodinâmica, freqüência cardíaca de 42 bpm, SpO2 de 73%, cianose central e de extremidades e pressão arterial de 120 × 70 mmHg. Foi proposta a realização de cateterismo e valvoplastia pulmonar via hemodinâmica. Por causa da impossibilidade de realização dessa técnica com sucesso, foi indicada a realização de cirurgia de Blalock-Taussig com implante de marca-passo. O procedimento foi realizado no dia seguinte sem intercorrências e a paciente teve alta hospitalar sete dias após o procedimento cirúrgico com SpO2 de 85%, hematócrito de 49% e melhora da dispnéia. CONCLUSÕES: O sucesso do procedimento anestésico para correção cirúrgica de cardiopatia congênita complexa demanda conhecimento da fisiopatologia da doença, bem como das particularidades inerentes à técnica anestésica utilizada.

CIRURGIA, Cardíaca; CIRURGIA, Cardíaca; DOENÇAS, Congênita

CLINICAL REPORT

Michelle Nacur Lorentz, TSA^I; Raquel Reis Soares, TSA^I; Cláudia Vargas Araújo Ribeiro^II; Friederike Wolff Valadares^I

^IAnestesiologista do Hospital Biocor

^IIAnestesiologista do Hospital Biocor e Santa Casa de Misericórdia de Belo Horizonte

Correspondence to

SUMMARY

BACKGROUND AND OBJECTIVES: Univentricular heart is a complex, rare, and severe cardiopathy, with no possibility of curative surgical treatment, associated with a high mortality in the first years of life. The objective of this article was to describe a rare case of an adult patient with uncorrected single ventricle who was admitted for pulmonary valvuloplasty but was submitted to a modified Blalock-Taussig and placement of an epicardic pacemaker. The complementary objective of this report was to address the anesthetic particularities of adult patients with uncorrected congenital cardiopathy.

CASE REPORT: A 34 years old female patient, weighing 60 kg, with a complex congenital cardiopathy with a single ventricle, important infundibular pulmonary stenosis and moderate pulmonary hypertension was admitted to the hospital without conditions to undergo surgical correction. The patient had a history several therapeutic bleedings to treat polycythemia. She was admitted due to worsening hypoxemia, an episode of syncope, and recent onset of third degree atrioventricular block. On admission, the patient was hemodynamically stable, heart rate of 42 bpm, SpO₂ 73%, central cyanosis and cyanosis of the extremities, and blood pressure 120 × 70 mmHg. Cardiac catheterization and pulmonary valvuloplasty were proposed. Due to the impossibility of success of this technique, Blalock-Taussig procedure with placement of a pacemaker was indicated. The procedure was performed in the following day without intercurrences, and the patient was discharged 7 days after the surgery, with SpO₂ 85%, hematocrit 49%, and improvement of the dyspnea.

CONCLUSIONS: The success of anesthesia for surgical correction of complex congenital cardiopathy requires knowledge on the pathophysiology of the disorder, as well as the particularities inherent to the anesthetic technique used.

Key Words: DISEASES, congenital: single ventricle; SURGERY, Cardiac: Blalock-Taussig, pacemaker placement.

RESUMEN

JUSTIFICATIVA Y OBJETIVOS: El ventrículo único es una cardiopatía compleja, rara y grave sin posibilidad de tratamiento quirúrgico curativo, asociada a una alta mortalidad durante la primera infancia. El objetivo de este artículo fue el de describir un caso raro de paciente adulto con ventrículo único no operado que se internó para la realización de valvoplastia pulmonar vía hemodinámica y que terminó siendo sometido a la cirugía de Blalock-Taussig modificado e implante de marcapaso epicárdico. Tuvo como objetivo complementario destacar las particularidades anestésicas del paciente adulto portador de cardiopatía congénita no corregida.

RELATO DEL CASO: Paciente de 34 años, 60 kg, portadora de cardiopatía congénita compleja tipo ventrículo único, estenosis infundíbulo valvar pulmonar importante e hipertensión pulmonar moderada. Admitida en el hospital sin condiciones de corrección quirúrgica y con historial anterior de varias sangrías terapéuticas para tratamiento de policitemía. Se le internó debido al empeoramiento de la hipoxemia, un episodio de síncope y bloqueo atrioventricular total (BAVT) de inicio reciente. En el momento de su internación presentaba estabilidad hemodinámica, frecuencia cardíaca de 42 lpm, SpO₂ de 73%, cianosis central y de extremidades y presión arterial de 120 × 70 mmHg. Fue propuesta la realización de cateterismo y valvoplastía pulmonar vía hemodinámica. Debido a la imposibilidad de la realización de esa técnica con éxito, fue indicada la realización de cirugía de Blalock-Taussig con implante de marcapaso. El procedimiento fue realizado al día siguiente sin intercurrencias y la paciente tuvo alta hospitalaria 7 días después del procedimiento quirúrgico con SpO₂ de 85%, hematócrito de 49% y mejoría de la disnea.

CONCLUSIONES: El éxito del procedimiento anestésico para la corrección quirúrgica de cardiopatía congénita compleja exige el conocimiento de la fisiopatología de la enfermedad, como también las particularidades inherentes a la técnica anestésica utilizada.

INTRODUCTION

A wide variety of cardiac defects share common characteristics that, physiologically, work as a single ventricular chamber and, therefore, are classified as "univentricular". Those defects include tricuspid atresia with a single right or left ventricle, double outlet right ventricle with noncommitted ventricular septal defect, and syndrome of left heart hypoplasia. Anatomically, those defects are very diverse, but functionally they behave as a single ventricle and are extremely severe complex cardiopathies, with a high mortality rate in the first year of life. Approximately 50% of the patients are dead 4 years after the diagnosis and, afterwards, it has a mortality rate of 4.8% per year. Restaino et al. described a case of single left ventricle in a 57-year old female who had not had corrective cardiac surgery; until that moment, only 10 cases of non-corrected single left ventricle who survived past age 50 had been reported in the literature ¹. Those cases demonstrate the rare occurrence of spontaneous compensation. In the study of patients with uncorrected single left ventricle, it was observed that the combination of double left ventricular inlet with transposition of the great vessels and moderate pulmonary stenosis or moderate pulmonary hypertension would allow, in some cases, an adequate balance between the systemic and pulmonary circulations, favoring blood oxygenation adequate for adult life. Surgical repair in those individuals is very difficult; therefore, only palliative surgeries are done or heart transplant. Repair of the ventricles requires an extremely favorable anatomy, which is not commonly found, although this was the case of the patient described by Ebert ². When the blood flow for the lungs is inadequate, palliative surgeries, with systemic-pulmonary shunt, are done to improve oxygenation. Among those procedures, one can use especially the modified Blalock-Taussig (subclavian-pulmonary anastomosis) or Fontan (cava-pulmonary anastomosis) procedure. The objective of this article was to report a case that, besides being rare, presented the particularity of having to submit a patient with pulmonary hypertension (PH) to Blalock-Taussig surgical correction.

CASE REPOT

A 34 years old female patient, weighing 60 kg, 1.64 m, with complex cyanotic congenital cardiopathy (single ventricle associated with severe infundibular pulmonary stenosis and moderate pulmonary hypertension). Recently, she had experienced one episode of syncope and developed third degree AV block, maintaining a heart rate (HR) of 42 bpm and blood pressure (BP) of 120× 70 mmHg. This was accompanied by tachydyspnea and recurring dizziness. On admission, she presented SpO₂ 73%, hematocrit (Ht) 70%, hemoglobin (Hb) 22.2 g.dL^-1, and INR 2.1. An echocardiogram confirmed "type E" single ventricle with double intlet and outlet, normally positioned vessels, and moderate to severe pulmonary stenosis; pressure in the pulmonary artery was 30 mmHg. Bleeding was performed to reduce polycythemia and central cyanosis, the patient was hydrated, vitamin K was administered, and a subcutaneous pacemaker was available. Cardiac catheterization was, then, performed in an attempt to dilate the left pulmonary artery, which was unsuccessful; the procedure was done under local anesthesia associated with conscious sedation with 2 mg of midazolam, 100 µg of fentanyl, and oxygen (O₂) 3 L.min^-1 by nasal catheter.

On the following day, the patient was transferred to the operating room for a surgical repair using the modified Blalock-Taussig in the right with Dacron prosthesis and placement of an epicardic pacemaker. The objective of the procedure was to improve oxygenation and decrease the recurring polycythemia. Intraoperative monitoring consisted of continuous electrocardiogram (ECG), pulse oximetry (SpO₂), capnograph, invasive blood pressure on the left radial artery (contralateral to the Blalock), nasopharyngeal temperature, urinary catheter, and serial blood gases. General balanced anesthesia was done with 2% sevoflurane, fentanyl, etomidate, and atracurium. Heparin, 1.5 mg.kg^-1, was administered before clamping the pulmonary artery and, at the end of the surgery, it was reversed with 70% of the dose of protamine. A FiO₂ of 0.5 mixed with room air was used, and due to the hemodynamic stability, inotropic agents were not necessary. At the end of the procedure, the patient was extubated, presenting SpO₂ 95%, which remained around 85% in the immediate postoperative period, when the Blalock was operational. On the day of the hospital discharge, the patient presented Hb 15.9 g.dL^-1 and Ht 49%. In the late postoperative period (one year after the surgery) the patient remained stable performing household chores with SpO₂ 83%.

DISCUSSION

Affecting approximately eight in every 1,000 live births ³, congenital cardiac defects are the most common human congenital deformity. Patients with single ventricle with left ventricular morphology and rudimentary anterior chamber represent 0.7% of all congenital cardiopathies ¹. Rare patients reach adulthood without palliative or corrective surgery, unless they also present pulmonary stenosis or mild to moderate pulmonary hypertension², since those factors can regulate pulmonary blood flow, allowing extended survival. The main causes of death are arrhythmias (atrial fibrillation) and congestive heart failure ⁴.

In the present case, third degree AV block was secondary to the natural evolution of the disease, because in this type of cardiopathy the region of the cardiac valves and the region of the atrioventricular node are commonly affected, leading to the late development of third degree AB block. Although this patient presented pulmonary stenosis, she developed pulmonary hypertension (PH), probably due to in situ thrombosis or hypoplasia of branches of the pulmonary tree. However, PH was not severe, and a low pulmonary blood flow predominated in this patient, since she presented cyanosis and severe hypoxemia. Therefore, the modified Blalock-Tausig procedure was performed, because it was necessary to increase the pulmonary blood flow to improve SpO₂, which was reduced due to a severe pulmonary stenosis. Initially, we thought of performing the surgical repair of Glenn (superior vena cava-pulmonary artery anastomosis); however, this technique should not be used in patients with pulmonary artery pressure greater than 15 mmHg, and this patient presented pulmonary artery pressure of 30 mmHg.

The physiological response of patients with single ventricle physiology to common interventions such as supplementary oxygen, mechanical ventilation, and vasoactive drugs is different than that of other patients ^5,6. With univentricular anatomy, circulations work in parallel, and both pulmonary and systemic circulations contain a mixture of oxygenated and non-oxygenated blood. Arterial oxygen saturations between 70% and 80% are physiologic for those patients; more elevated saturations, obtained by using supplementary methods, are deleterious for their physiology. Therefore, anesthetic handling of patients with parallel circulations demands deep understanding of the physiopathology of the disease, as well as individualization of the anesthetic technique. In complex congenital cardiopathies, the choice of anesthetic drugs is not as important as the knowledge and adequate handling of hemodynamic parameters ⁶. Successful management of those patients usually demands maintenance of SpO₂ around 75%, and SvO₂ around 50%, in an attempt to maintain a balance between both circulations.

Monitoring the SvO₂ seems to be more adequate in those patients, because provides the level of O₂ supplied to tissues, and some authors have indicated that it should be done continuously in the superior vena cava ⁷. The P_ETCO₂ in patients with low pulmonary blood flow loses its sensitivity as an indicator of the arterial pressure of CO₂ (PaCO₂) because, in those cases, the dead space is increased, which increases the Pa-P_ETCO₂ gradient. The main objective of anesthesia is to maintain the relationship between pulmonary and systemic output close to one. In parallel circulations, an excess of pulmonary blood flow decreases systemic blood flow, leading to a reduction in cardiac output, lactic acidosis, and myocardial dysfunction ⁸. On the other hand, low pulmonary blood flow leads to severe hypoxemia, compromising the life of the patient. Thus, the management of those patients is based, mainly, on adequate ventilation. High FiO₂, hypocapnia, and maneuvers that decrease pulmonary vascular pressure should be avoided, because they generate pulmonary vasodilation with high pulmonary blood flow, decreasing systemic blood flow. But hypoxemia and hypercapnia should also be avoided because they cause pulmonary vasoconstriction, shunting blood to the systemic circulation. Usually, a FiO₂ of 0.5 mixed with room air is used, although some cases of patients with increased pulmonary blood flow require the addition of CO₂ to the ventilating system to control pulmonary vasodilation ⁹. For a long time, anesthesiologists used SpO₂ as a guide in those cases. Nowadays, it is known that both SpO₂ and hemodynamic parameters, such as BP and HR, for intraoperative monitoring of those patients are supplanted by biologic markers, like SvO₂ (saturation of mixed venous blood) and lactate levels ^10,11. Saturation of mixed venous blood should be maintained around 50%, and the tendency of lactate levels to increase or decrease is more important than absolute levels.

Early extubation can be done, as long as the patient is breathing spontaneously and is not at risk of retaining CO₂; it can also be advantageous because it improves hemodynamics. However, many adults with congenital cardiopathies have altered pulmonary function, and this can be relevant when deciding for the early extubation of the patient.

REFERENCES

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Anesthesia for blalock-taussig shunt and pacemaker placement in an adult patient with univentricular heart. Case report

Anestesia para corrección quirúrgica de blalock-taussig e implante de marcapaso en adulto portador de ventrículo único. Relato de caso

Publication Dates

• Publication in this collection
  15 Sept 2008
• Date of issue
  June 2008

History

• Received
  28 Mar 2007
• Accepted
  19 Feb 2008