Epidural
Anesthesia in Patients With Palliated Congenital Heart Disease
Cyanotic
Robert S. Holzman, MD, Charles D. Nargozian, MD, Richard Marnach, MD, and Curtis 0. McMillan, MD
P
ATIENTS WITH palliated cyanotic congenital heart disease (CHD) are surviving in greater numbers, and present for noncardiac surgical procedures that demand an understanding of progressive cyanotic CHD and the physiologic implications of varied anesthetic techniques. As these patients grow into young adulthood, they are desirous of discussing their anesthetic options, and may express a strong preference to retain consciousness and avoid a general anesthetic. Carefully administered regional anesthesia has a place in the options offered to such patients, and, therefore, two cases are presented to illustrate experience with these patients and epidural anesthesia. CASE REPORTS Patient
no. 1
A 17.year-old, Wkg boy with a d-transposition of the great arteries, hypoplastic right ventricle (RV), ventricular septal defect (atrioventricular canal type), atria1 septal defect (ASD), small patent ductus arteriosus (PDA), and an overriding tricuspid valve (straddling the hypoplastic right ventricle and the left ventricle) presented for a right inguinal herniorrhaphy (Fig 1). The patient took digoxin and furosemide. Prior surgical procedures included a balloon atria1 septostomy with a pulmonary artery band, and a modified Fontan procedure (right atria1 to right pulmonary artery anastomosis with intra-atria1 baffle). After the Fontan procedure, there was an elevated right atrial pressure (24 to 28 mmHg), with a 4-mmHg gradient across the right atrial-pulmonary artery [RARPA] anastomosis, but no discrete obstruction. There was also a mild right-to-left atrial-level shunt with a 12-mmHg gradient across a small atria1 septal defect (mean right atria1 pressure was 30 mmHg, and mean left atria1 pressure was 18 mmHg), a normal cardiac output, and oxygen saturation by pulse oximetry (S,oz) of 86% to 88% on room air. His preoperative hematocrit was 53%. Patient
no. 2
A 30-year-old, 50-kg woman with a history of tetralogy of Fallot with pulmonary atresia, an interatrial communication (ASD or patent foramen ovale [PFO]), and large aortopuhnonary collaterals presented for exploratory laparotomy for excision of an ovarian cyst (Fig 1). The patient took tetracycline, digoxin, and furosemide. Prior surgical procedures included a central shunt, left pleurectomy, odontectomy, and bilateral tubal ligation. Cardiac catheterization data prior to central shunt placement showed an aortic saturation of 78% on room air, with a right atria1 pressure of 9 mmHg, left atrial pressure of 8 mmHg, and a right ventricular pressure of 133113 mmHg. Her ratio of pulmonary to systemic
From the Departments of Anesthesia, the Children’s Hospital and Harvard Medical School, Boston, MA. presented in part at the Section on Anesthesiology, American Academy of Pediabics, Seattle, WA, April 28 to May 3, 1990. Address reprint requests to Robert S. Holzman, MD, Department of Anesthesia, Children’s Hospital, 300 Longwood Ave, Boston, MA 021I5. Copyright 0 I992 by W. B. Saunders Company IO53-0770/92/0603-0021$03.00/O Key worak epidural anesthesia, cyanosis, congenital heart defects
340
blood flow (Q,/Q,) was 1.5:1, and her preoperative hematocrit was 56%. Both patients received nothing by mouth from midnight on the day of surgery, and premeditation was not administered to either patient. After placement of an intravenous catheter, routine noninvasive monitors, and a pulse oximeter, an epidural catheter was inserted in a standard manner. After returning the patients to the supine position, they were each given 500 mL ( - 10 mL/kg) of lactated Ringer’s solution over approximately 20 minutes to supplement their intravascular volume while closely monitoring blood pressure, heart rate, and $0~. Both patients had test doses with 3 mL of 2% lidocaine with 1:200,000 epinephrine, followed by 0.5% bupivacaine (patient 1) or 2% lidocaine (patient 2) to achieve surgical anesthesia. These doses were administered in 3-mL increments with 3 minutes between doses. Sensory levels were checked in both patients only after a 20-mL dose had been administered; patient 1 achieved a sensory level of Ta, patient 2 a level of Ti,,. Patient I received a total of 150 ug of fentanyl and 1.5 mg of midazolam, while patient 2 received 75 pg of fentanyl and 2.5 mg of midazolam as intravenous anesthetic adjuncts. Both patients received prophylaxis for subacute bacterial endocarditis. Surgery proceeded uneventfully once anesthesia was established, which was 45 minutes after beginning to place the epidural in patient 1. and 40 minutes in patient 2. Surgery lasted for 75 minutes in patient 1, and 50 minutes in patient 2. Figure 2 presents the time course of epidural placement, dosing, sensory level achieved, duration of surgery, and intraoperative vital signs. Figure 3 illustrates intraoperative oxygen saturations.
DISCUSSION
Little in the literature exists about conduction anesthesia in patients with cyanotic CHD. Most references offer caution against techniques that tend to reduce the systemic vascular resistance (SVR); only one recent abstract suggests that slow incremental dosing of the local anesthetic during epidural blockade minimizes systemic hypotension. i Successful epidural anesthesia has been reported several timeszm4 and reviewed5 in conjunction with Eisenmenger’s syndrome. Mallampati used low thoracic epidural analgesia for cholecystectomy in a patient with partial anomalous pulmonary venous return, pulmonary hypertension, and an atria1 septal defect; epidural analgesia was chosen because of prior pulmonary infection with a general anesthetic.” Selsby and Sugden reported successful epidural anesthesia for a bilateral inguinal herniorrhaphy in a patient with Eisenmenger’s syndrome.7 In contrast to the dearth of reports in the general surgical population, much of the anesthetic literature in this area has been devoted to the obstetrical patient with cardiac disease. Ostheimer and Alper considered a variety of anesthetic options for pregnant patients with heart disease including CHD, while warning against the consequences of hypotension in this population.8 Krivosic-Horber et al reported a 3-year experience in France with 38 women, 14 of whom had CHD, and noted epidural analgesia as improving labor and vaginal delivery; nevertheless, they recommended general anesthesia for cesarean section.” A
Journalof Cardiothoracic and VascularAnesthesia,
Vol6,
No 3 (June), 1992: pp 340-343
EPIDURAL ANESTHESIA
IN HEART DISEASE
PatientNo. 1
U
Qp/Qs =0.9
341
PatientNo. 2
QplQs =
1.5~1
Fig 1. Patient histories. Patient 1. Cardiac anatomy: 1. d-transposition; 2. hypoplastic RV; 3. ADS; 4. small PDA; 5. overriding tricuspid valve. Procedure: right inguinal herniorhaphy. Age, 17.5 years; weight, 54 kg; hematocrit, 83%; room air saturation, 80%; physical status, 3; New York Heart Association class, 3. Prior procedures: 1. balloon atrial septostomy; 2. pulmonary artery band; 3. ADS or PFO; 4. large aorto-pulmonary collaterals. Procedure: exploratory laparotomy. Age, 30 years; weight, 50 kg; hematocrit, 58%; room air saturation, 85%; physical status, 3; NYHA class, 3; Prior procedures: 1. central shunt; 2. left pleurectomy; 3. odontectomy; 4. tubal ligation.
mortality rate of 52% was noted by Elkayam et al, maternal and they recommended general anesthesia for patients with cyanotic CHD with decreased pulmonary blood flow.iO Intrathecal morphine without local anesthetic has been reported in a parturient with a single ventricle, following a pulmonary artery band and a subsequent Glenn shunt,” as well as in a recent report by Pollack et al in a parturient with Eisenmenger’s syndrome and a patent ductus arteriosus.12 The two patients reported here requested conduction anesthesia, and this was done through the use of slow, careful dosing of the epidural block, and routine, noninvasive monitoring. The principal concern in patients with passive conduits, such as the Fontan, is an adequate central blood volume and pressure in order to perfuse the pulmonary circulation, along with unimpaired ventricular function. For the patient with a right-to-left shunt, on the other hand, such as tetralogy of Fallot, adequacy of pulmonary blood flow is, in part, related to prevention of significant
Fig 2. Summary of vital signs in patients 1 and 2. SBP, systolic blood pressure; DBP, diastolic blood pressure; HR. heart rate. Surgery began 40 minutes after epidural catheter placement in patient 1 and lasted 40 minutes. Surgery began 45 minutes after epidural catheter placement in patient 2 and lasted 75 minutes.
decreases in SVR. The profound sympathectomy associated with major conduction anesthesia carries implications for both of these considerations; lowering the SVR will contribute to peripheral pooling, thereby lowering the central blood volume, while at the same time, a sympathectomy can decrease SVR through the lowering of arteriolar tone. Particular attention was given to the blood pressure. While striving to keep the mean arterial pressure within a reasonable clinical range, it was also expected to see an increase in the pulse pressure as a result of sympathetic blockade, peripheral vasodilatation, and modest volume loading. Interesting blood pressure findings occurred in both patients, for unclear reasons. Patient 1 experienced an uncharacteristic narrowing of the pulse pressure (decrease in systolic blood pressure in excess of the decrease in diastolic blood pressure) following epidural blockade, which remained stable throughout surgery and was accompanied by an increase in S,Oz. Patient 2 experienced increases in systolic and diastolic blood pressures 30 minutes after the start of surgery, which were also accompanied by an increase in S,Or. After the epidural was reinjected with lidocaine, the blood pressure remained unchanged, despite satisfactory analgesia. Approximately 10 mL/kg of lactated Ringer’s solution was administered to both patients over a period of 20 minutes, which was approximately 66% of their NPO deficit. Pulse oximetry was expected to be a sensitive monitor in both patients for the adequacy of pulmonary blood flow, their principal determinant of oxygenation. While end-tidal carbon dioxide would also be a reflection of the adequacy of pulmonary blood flow, it is difficult to quantitate in a spontaneously breathing, nonintubated patient. The placement of a flow-directed pulmonary artery catheter (PAC) may be difficult or impossible in patients with CHD.r3 Placement of a PAC in patients with CHD with shunts or pulmonary outflow tract obstruction may require fluoroscopic guidance, because balloon inflation may not be enough to guide the catheter into the pulmonary circulation. Furthermore, thermodilution cardiac output determinations will be erroneous in such patients whether due to left-to-right or right-to-left shunting. Separate mea-
HOLZMAN ET AL
Epldural placement
A
Fig 3. Summary of oxygen saturations by pulse oximetry (S,O,) during epidural anesthesia for patients 1 and 2. Shaded bars indicate duration of epidural placement and dosing of local anesthetic.
surements of systemic and pulmonary blood flow are necessary to describe the resistances in each circulation.14 Although a paucity of studies exists reporting complications of PACs in patients with CHD, Blanco-Pajon et al noted atria1 ectopic beats in 25%, atria1 tachycardia in 3.3%, and ectopic ventricular beats in 60.8% of 119 patients undergoing PAC insertion for cardiac surgery.15 In a retrospective study of 700 pediatric patients, Hammerer observed paroxysmal supraventricular tachycardia in 3.6%, sinus bradycardia in 2.6%, junctional rhythm in 1.4%, second-degree arteriovenous block in 1.3%, ventricular fibrillation in l.l%, sinus tachycardia in l%, complete heart block in l%, asystole and atria1 flutter in 0.3%, and ventricular tachycardia in 0.15%.16 Asystole resulted in immediate death in one child with severe pulmonary hypertension. Four of seven complete heart blocks occurred in patients with pulmonary hypertension. A central venous pressure catheter would be easier to place into the superior vena cava, but with pulmonary hypertension and variable shunting, it probably would not be as useful in overall patient management as the pulse oximeter in judging adequacy of pulmonary blood flow, shunt, and oxygenation. Furthermore, right atria1 pressures were known to be elevated in both patients, and may not have provided suitable guidance for volume therapy. The release of endogenous catecholamines in patients with cyanotic CHD is associated with an increase in right-to-left shunting through effects on pulmonary vascular resistance and pulmonary infundibular tone. Patients with right-to-left shunting may worsen their shunt with a decrease in SVR. While conduction blockade will lower SVR, it is postulated that the rate of lowering is more important than the decrease itself, and the rate can be lowered slowly by the gradual introduction of conduction anesthesia.1 As SVR decreases under the influence of a progressive sympathetic blockade, preload is reduced, and the right atrium has less blood to eject into the high-resistance pulmonary arteriolar bed. Cautious volume loading will compensate for this slow afterload reduction and vasodilatation. As an alternative, general anesthetics carry their own set of risks,
including possible inadequate analgesia with a consequent increase in pulmonary vascular resistance, impaired venous return, and decreased cardiac output due to the effects of positive-pressure ventilation, the potential for airway mishaps during airway manipulation, as well as the depressant effects of volatile anesthetic agents on compromised myocardial function. Polycythemia may contribute to tissue ischemia in lowflow states as a part of the increase in blood viscosity.” It has been suggested that such rheological abnormalities should be taken into account when planning to alter microcirculatory flow and tissue oxygen delivery.rs Sympathectomy during regional anesthesia generally improves microvascular flow. Regional anesthesia has been shown to reduce the frequency of deep vein thrombosis, as well as intraoperative and postoperative blood loss during total hip replacement.r9 These two patients fasted overnight preoperatively, and were first cases of the day; a 12-hour overnight fast has been shown to not result in a significant increase in blood viscosity in normal patients, but a 24-hour fast did result in such an increase.20 Blood viscosity also affects SVR, cardiac output, and tissue oxygen delivery.21 Consideration needs to be given to the NPO interval in these patients; intravenous fluids may be required for cases that are not scheduled early in the day. Platelet half-life in patients with Eisenmenger’s complex is significantly shortened, and is responsive to lowering of the hematocrit.12 Erythrocytapheresis is another strategy for lowering viscosity by removing red cells from the circulation.23 Although the effects of regional anesthesia on coagulation in polycythemic cyanotic CHD patients are unknown, general anesthetics and surgery are known to contribute to hypercoagulable states; perhaps another added benefit of regional blockade for such patients is the avoidance of some of these adverse hemorheological effects. At the same time, patients with significant polycythemia secondary to their cyanotic CHD should be considered at risk for increased bleeding, and should be evaluated by history and standard laboratory examinations, although this does not typically occur until hematocrits greater than those of the present patients are encountered.24Js The psychological benefits of regional anesthesia were important for these patients. McNamara noted that the attitude of the adult patient with CHD is often influenced by restricted and overprotected childhoods, and multiple contacts with hospitals and doctorsz6 With a history of multiple hospitalizations and intense medical care all of their lives, these patients were reluctant to allow themselves to become unconscious and “lose control” if they could avoid it. Regional anesthesia allowed them to remain conscious while small amounts of sedation provided anxiolysis. Spinal anesthesia, as an alternative, is less desirable, because of the rapid onset of sympathetic blockade, and is not as titratable as progressive epidural analgesia. Continuous spinal anesthesia, more recently available with microcatheter techniques, offers another option for the more gradual onset of sympathetic blockade.
EPIDURAL ANESTHESIA
IN HEART DISEASE
343
Both patients were monitored with an electrocardiogram, oscillometric blood pressure cuff, precordial stethoscope for breath and heart sounds, and a pulse oximeter. In order to support the SVR, particularly in patient 2 with tetralogy of Fallot and a systemic-to-pulmonary artery shunt, the authors were prepared to treat with phenylephrine, but found it unnecessary because S,Oz did not change significantly from baseline, and the patient’s mental status remained the same. Phenylephrine was the drug of choice as a directly acting vasoconstrictor in order to increase SVR, with specific cui-receptor, and no l3-adrenergic activity. For the same pharmacologic reasons, methoxamine would be an equivalent choice. Both patients received supplemental oxygen for its possi-
ble salutary effect on pulmonary vascular resistance, as well as for any contribution that it could make to an increased margin of safety. While sedation may contribute to hypercarbia with its potential for adversely affecting pulmonary vascular resistance and endogenous catecholamine elaboration, judicious conscious sedation was used without any apparent deleterious effects. Finally, air bubbles were avoided, and an air filter was used in the intravenous tubing.
ACKNOWLEDGMENT
The authors thank Dr Paul R. Hickey for his kind review and thoughtful
suggestions
about the manuscript.
REFERENCES 1. Christopherson R, Beattie C, Crowley H, et al: Hypotension following epidural blockade in high-risk patients is avoidable. Anesth Analg 7OSlS450, 1990 (suppl) 2. Asling JH: Epidural anesthesia in Eisenmenger’s syndrome: A case report. Anesth Analg 53:965-968,1974 3. Crawford JS: A pregnant patient with Eisenmenger’s syndrome. Br J Anaesth 43:1091-1094,197l 4. Spinnato JA, Kraynack BJ, Cooper MW: Eisenmenger’s syndrome in pregnancy: Epidural anesthesia for elective cesarian section. N Engl J Med 304:1215-1217,198l 5. Foster JM, Jones RM: The anaesthetic management of the Eisenmenger syndrome. Ann R Coll Surg Engl66:353-355,1984 6. Mallampati SR: Low thoracic epidural anaesthesia for elective cholecystectomy in a patient with congenital heart disease and pulmonary hypertension. Can Anaesth Sot J 30:72-76,1983 7. Selsby DS, Sugden JC: Epidural anaesthesia for bilateral inguinal herniorrhaphy in Eisenmenger’s syndrome. Anaesthesia 44:130-132, 1989 8. Ostheimer GW, Alper MH: Intrapartum anesthetic management of the pregnant patient with heart disease. Clin Obstet Gynecol 18:81-97,1975 9. Krivosic-Horber R, Ducroux G, Beague D: L’anesthesie chez la parturiente cardiaque. Trente-huit cas. Anesth Analg (Paris) 37:681-684, 1980 10. Elkayam U, Gileicher N (eds): Cardiac Problems in Pregnancy. New York, NY, Liss, 1982, pp 1953-1960 11. Ahmad S, Hawes D, Dooley S, et al: Intrathecal morphine in a parturient with a single ventricle. Anesthesiology 54:515-517, 1981 12. Pollack KL, Chestnut DH, Wenstrom KD: Anesthetic management of a parturient with Eisenmenger’s syndrome. Anesth Analg 70:212-215,199O 13. Loomis JC: Care of the pediatric patient following cardiovascular surgery, in Ream AK, Fogdall RP (eds): Acute Cardiovascular Management: Anesthesia and Intensive Care. Philadelphia, PA, Lippincott, 1982, p 639 14. Jarmakani JM: Cardiac catheterization, in Moss AJ, Adams
FH, Emmanouilides GC (eds): Heart Disease in Infants, Children and Adolescents. Baltimore, MD, Williams & Wilkins, 1977 pp 130-147 15. Blanco-Pajon MJ, Fernandez de la Reguera G, HurtadoReyes IC, et al: Complicaciones de1 uso de1 cateter PE flotation pulmonar en cirugia cardiovascular: Etudio prospective. Arch Inst Cardiol Mex 56:147-155, 1986 16. Hammerer I: Das Risko Der Herzkatheter-Untersuchung. Eine retrospektive auswertung der komplikationen nach 700 untersuchungen. III. Rhythmusstorungen. Padiatr Padol 14:393-403, 1979 17. Lowe GD: Blood rheology in vitro and in vivo. Baillieres Clin Haematol1:597-636, 1987 18. Scholz PM, Kinney JM, Chien S: Effects of major abdominal operations on human blood rheology. Surgery 77:351-359, 1975 19. Modig J: Influence of regional anesthesia, local anesthetics, and sympathomimetics on the pathophysiology of deep vein thrombosis. Acta Chir Stand 55:119-124,1989 (suppl) 20. Aronson HB, Horne T, Blondheim SH, Davidson JT: Blood viscosity and the overnight fast. Can Anaesth Sot J 27:550-552, 1980 Anesth 21. Gordon RJ, Ravin MB: Rheology and anesthesiology. Analg 57:252-261, 1978 22. Lopes AA, Maeda NY, Ebaid M, et al: Effect of intentional hemodilution on platelet survival in secondary pulmonary hypertension. Chest 95:1207-1210, 1989 23. Zoller WG, Kellner H, Spengel FA: Erythrocytapheresis. A method for rapid extracorporeal elimination of erythrocytes. Klin Wochenschr 66:404-409,1988 24. Gross MA, Keefer V, Liebman J: The platelets in cyanotic heart disease. Pediatrics 42:651-658, 1968 25. Maurer HM, h4cCue CM, Robertson LW, Haggins JC: Correction of platelet dysfunction and bleeding in cyanotic congenital heart disease by simple red cell volume reduction. Am J Cardio135:831-835, 1975 26. McNamara DG: The adult with congenital heart disease. Curr Probl Cardiol 14:57-114,1989
Anesthesia in Patients With Palliated Congenital Heart Disease
Cyanotic
Robert S. Holzman, MD, Charles D. Nargozian, MD, Richard Marnach, MD, and Curtis 0. McMillan, MD
P
ATIENTS WITH palliated cyanotic congenital heart disease (CHD) are surviving in greater numbers, and present for noncardiac surgical procedures that demand an understanding of progressive cyanotic CHD and the physiologic implications of varied anesthetic techniques. As these patients grow into young adulthood, they are desirous of discussing their anesthetic options, and may express a strong preference to retain consciousness and avoid a general anesthetic. Carefully administered regional anesthesia has a place in the options offered to such patients, and, therefore, two cases are presented to illustrate experience with these patients and epidural anesthesia. CASE REPORTS Patient
no. 1
A 17.year-old, Wkg boy with a d-transposition of the great arteries, hypoplastic right ventricle (RV), ventricular septal defect (atrioventricular canal type), atria1 septal defect (ASD), small patent ductus arteriosus (PDA), and an overriding tricuspid valve (straddling the hypoplastic right ventricle and the left ventricle) presented for a right inguinal herniorrhaphy (Fig 1). The patient took digoxin and furosemide. Prior surgical procedures included a balloon atria1 septostomy with a pulmonary artery band, and a modified Fontan procedure (right atria1 to right pulmonary artery anastomosis with intra-atria1 baffle). After the Fontan procedure, there was an elevated right atrial pressure (24 to 28 mmHg), with a 4-mmHg gradient across the right atrial-pulmonary artery [RARPA] anastomosis, but no discrete obstruction. There was also a mild right-to-left atrial-level shunt with a 12-mmHg gradient across a small atria1 septal defect (mean right atria1 pressure was 30 mmHg, and mean left atria1 pressure was 18 mmHg), a normal cardiac output, and oxygen saturation by pulse oximetry (S,oz) of 86% to 88% on room air. His preoperative hematocrit was 53%. Patient
no. 2
A 30-year-old, 50-kg woman with a history of tetralogy of Fallot with pulmonary atresia, an interatrial communication (ASD or patent foramen ovale [PFO]), and large aortopuhnonary collaterals presented for exploratory laparotomy for excision of an ovarian cyst (Fig 1). The patient took tetracycline, digoxin, and furosemide. Prior surgical procedures included a central shunt, left pleurectomy, odontectomy, and bilateral tubal ligation. Cardiac catheterization data prior to central shunt placement showed an aortic saturation of 78% on room air, with a right atria1 pressure of 9 mmHg, left atrial pressure of 8 mmHg, and a right ventricular pressure of 133113 mmHg. Her ratio of pulmonary to systemic
From the Departments of Anesthesia, the Children’s Hospital and Harvard Medical School, Boston, MA. presented in part at the Section on Anesthesiology, American Academy of Pediabics, Seattle, WA, April 28 to May 3, 1990. Address reprint requests to Robert S. Holzman, MD, Department of Anesthesia, Children’s Hospital, 300 Longwood Ave, Boston, MA 021I5. Copyright 0 I992 by W. B. Saunders Company IO53-0770/92/0603-0021$03.00/O Key worak epidural anesthesia, cyanosis, congenital heart defects
340
blood flow (Q,/Q,) was 1.5:1, and her preoperative hematocrit was 56%. Both patients received nothing by mouth from midnight on the day of surgery, and premeditation was not administered to either patient. After placement of an intravenous catheter, routine noninvasive monitors, and a pulse oximeter, an epidural catheter was inserted in a standard manner. After returning the patients to the supine position, they were each given 500 mL ( - 10 mL/kg) of lactated Ringer’s solution over approximately 20 minutes to supplement their intravascular volume while closely monitoring blood pressure, heart rate, and $0~. Both patients had test doses with 3 mL of 2% lidocaine with 1:200,000 epinephrine, followed by 0.5% bupivacaine (patient 1) or 2% lidocaine (patient 2) to achieve surgical anesthesia. These doses were administered in 3-mL increments with 3 minutes between doses. Sensory levels were checked in both patients only after a 20-mL dose had been administered; patient 1 achieved a sensory level of Ta, patient 2 a level of Ti,,. Patient I received a total of 150 ug of fentanyl and 1.5 mg of midazolam, while patient 2 received 75 pg of fentanyl and 2.5 mg of midazolam as intravenous anesthetic adjuncts. Both patients received prophylaxis for subacute bacterial endocarditis. Surgery proceeded uneventfully once anesthesia was established, which was 45 minutes after beginning to place the epidural in patient 1. and 40 minutes in patient 2. Surgery lasted for 75 minutes in patient 1, and 50 minutes in patient 2. Figure 2 presents the time course of epidural placement, dosing, sensory level achieved, duration of surgery, and intraoperative vital signs. Figure 3 illustrates intraoperative oxygen saturations.
DISCUSSION
Little in the literature exists about conduction anesthesia in patients with cyanotic CHD. Most references offer caution against techniques that tend to reduce the systemic vascular resistance (SVR); only one recent abstract suggests that slow incremental dosing of the local anesthetic during epidural blockade minimizes systemic hypotension. i Successful epidural anesthesia has been reported several timeszm4 and reviewed5 in conjunction with Eisenmenger’s syndrome. Mallampati used low thoracic epidural analgesia for cholecystectomy in a patient with partial anomalous pulmonary venous return, pulmonary hypertension, and an atria1 septal defect; epidural analgesia was chosen because of prior pulmonary infection with a general anesthetic.” Selsby and Sugden reported successful epidural anesthesia for a bilateral inguinal herniorrhaphy in a patient with Eisenmenger’s syndrome.7 In contrast to the dearth of reports in the general surgical population, much of the anesthetic literature in this area has been devoted to the obstetrical patient with cardiac disease. Ostheimer and Alper considered a variety of anesthetic options for pregnant patients with heart disease including CHD, while warning against the consequences of hypotension in this population.8 Krivosic-Horber et al reported a 3-year experience in France with 38 women, 14 of whom had CHD, and noted epidural analgesia as improving labor and vaginal delivery; nevertheless, they recommended general anesthesia for cesarean section.” A
Journalof Cardiothoracic and VascularAnesthesia,
Vol6,
No 3 (June), 1992: pp 340-343
EPIDURAL ANESTHESIA
IN HEART DISEASE
PatientNo. 1
U
Qp/Qs =0.9
341
PatientNo. 2
QplQs =
1.5~1
Fig 1. Patient histories. Patient 1. Cardiac anatomy: 1. d-transposition; 2. hypoplastic RV; 3. ADS; 4. small PDA; 5. overriding tricuspid valve. Procedure: right inguinal herniorhaphy. Age, 17.5 years; weight, 54 kg; hematocrit, 83%; room air saturation, 80%; physical status, 3; New York Heart Association class, 3. Prior procedures: 1. balloon atrial septostomy; 2. pulmonary artery band; 3. ADS or PFO; 4. large aorto-pulmonary collaterals. Procedure: exploratory laparotomy. Age, 30 years; weight, 50 kg; hematocrit, 58%; room air saturation, 85%; physical status, 3; NYHA class, 3; Prior procedures: 1. central shunt; 2. left pleurectomy; 3. odontectomy; 4. tubal ligation.
mortality rate of 52% was noted by Elkayam et al, maternal and they recommended general anesthesia for patients with cyanotic CHD with decreased pulmonary blood flow.iO Intrathecal morphine without local anesthetic has been reported in a parturient with a single ventricle, following a pulmonary artery band and a subsequent Glenn shunt,” as well as in a recent report by Pollack et al in a parturient with Eisenmenger’s syndrome and a patent ductus arteriosus.12 The two patients reported here requested conduction anesthesia, and this was done through the use of slow, careful dosing of the epidural block, and routine, noninvasive monitoring. The principal concern in patients with passive conduits, such as the Fontan, is an adequate central blood volume and pressure in order to perfuse the pulmonary circulation, along with unimpaired ventricular function. For the patient with a right-to-left shunt, on the other hand, such as tetralogy of Fallot, adequacy of pulmonary blood flow is, in part, related to prevention of significant
Fig 2. Summary of vital signs in patients 1 and 2. SBP, systolic blood pressure; DBP, diastolic blood pressure; HR. heart rate. Surgery began 40 minutes after epidural catheter placement in patient 1 and lasted 40 minutes. Surgery began 45 minutes after epidural catheter placement in patient 2 and lasted 75 minutes.
decreases in SVR. The profound sympathectomy associated with major conduction anesthesia carries implications for both of these considerations; lowering the SVR will contribute to peripheral pooling, thereby lowering the central blood volume, while at the same time, a sympathectomy can decrease SVR through the lowering of arteriolar tone. Particular attention was given to the blood pressure. While striving to keep the mean arterial pressure within a reasonable clinical range, it was also expected to see an increase in the pulse pressure as a result of sympathetic blockade, peripheral vasodilatation, and modest volume loading. Interesting blood pressure findings occurred in both patients, for unclear reasons. Patient 1 experienced an uncharacteristic narrowing of the pulse pressure (decrease in systolic blood pressure in excess of the decrease in diastolic blood pressure) following epidural blockade, which remained stable throughout surgery and was accompanied by an increase in S,Oz. Patient 2 experienced increases in systolic and diastolic blood pressures 30 minutes after the start of surgery, which were also accompanied by an increase in S,Or. After the epidural was reinjected with lidocaine, the blood pressure remained unchanged, despite satisfactory analgesia. Approximately 10 mL/kg of lactated Ringer’s solution was administered to both patients over a period of 20 minutes, which was approximately 66% of their NPO deficit. Pulse oximetry was expected to be a sensitive monitor in both patients for the adequacy of pulmonary blood flow, their principal determinant of oxygenation. While end-tidal carbon dioxide would also be a reflection of the adequacy of pulmonary blood flow, it is difficult to quantitate in a spontaneously breathing, nonintubated patient. The placement of a flow-directed pulmonary artery catheter (PAC) may be difficult or impossible in patients with CHD.r3 Placement of a PAC in patients with CHD with shunts or pulmonary outflow tract obstruction may require fluoroscopic guidance, because balloon inflation may not be enough to guide the catheter into the pulmonary circulation. Furthermore, thermodilution cardiac output determinations will be erroneous in such patients whether due to left-to-right or right-to-left shunting. Separate mea-
HOLZMAN ET AL
Epldural placement
A
Fig 3. Summary of oxygen saturations by pulse oximetry (S,O,) during epidural anesthesia for patients 1 and 2. Shaded bars indicate duration of epidural placement and dosing of local anesthetic.
surements of systemic and pulmonary blood flow are necessary to describe the resistances in each circulation.14 Although a paucity of studies exists reporting complications of PACs in patients with CHD, Blanco-Pajon et al noted atria1 ectopic beats in 25%, atria1 tachycardia in 3.3%, and ectopic ventricular beats in 60.8% of 119 patients undergoing PAC insertion for cardiac surgery.15 In a retrospective study of 700 pediatric patients, Hammerer observed paroxysmal supraventricular tachycardia in 3.6%, sinus bradycardia in 2.6%, junctional rhythm in 1.4%, second-degree arteriovenous block in 1.3%, ventricular fibrillation in l.l%, sinus tachycardia in l%, complete heart block in l%, asystole and atria1 flutter in 0.3%, and ventricular tachycardia in 0.15%.16 Asystole resulted in immediate death in one child with severe pulmonary hypertension. Four of seven complete heart blocks occurred in patients with pulmonary hypertension. A central venous pressure catheter would be easier to place into the superior vena cava, but with pulmonary hypertension and variable shunting, it probably would not be as useful in overall patient management as the pulse oximeter in judging adequacy of pulmonary blood flow, shunt, and oxygenation. Furthermore, right atria1 pressures were known to be elevated in both patients, and may not have provided suitable guidance for volume therapy. The release of endogenous catecholamines in patients with cyanotic CHD is associated with an increase in right-to-left shunting through effects on pulmonary vascular resistance and pulmonary infundibular tone. Patients with right-to-left shunting may worsen their shunt with a decrease in SVR. While conduction blockade will lower SVR, it is postulated that the rate of lowering is more important than the decrease itself, and the rate can be lowered slowly by the gradual introduction of conduction anesthesia.1 As SVR decreases under the influence of a progressive sympathetic blockade, preload is reduced, and the right atrium has less blood to eject into the high-resistance pulmonary arteriolar bed. Cautious volume loading will compensate for this slow afterload reduction and vasodilatation. As an alternative, general anesthetics carry their own set of risks,
including possible inadequate analgesia with a consequent increase in pulmonary vascular resistance, impaired venous return, and decreased cardiac output due to the effects of positive-pressure ventilation, the potential for airway mishaps during airway manipulation, as well as the depressant effects of volatile anesthetic agents on compromised myocardial function. Polycythemia may contribute to tissue ischemia in lowflow states as a part of the increase in blood viscosity.” It has been suggested that such rheological abnormalities should be taken into account when planning to alter microcirculatory flow and tissue oxygen delivery.rs Sympathectomy during regional anesthesia generally improves microvascular flow. Regional anesthesia has been shown to reduce the frequency of deep vein thrombosis, as well as intraoperative and postoperative blood loss during total hip replacement.r9 These two patients fasted overnight preoperatively, and were first cases of the day; a 12-hour overnight fast has been shown to not result in a significant increase in blood viscosity in normal patients, but a 24-hour fast did result in such an increase.20 Blood viscosity also affects SVR, cardiac output, and tissue oxygen delivery.21 Consideration needs to be given to the NPO interval in these patients; intravenous fluids may be required for cases that are not scheduled early in the day. Platelet half-life in patients with Eisenmenger’s complex is significantly shortened, and is responsive to lowering of the hematocrit.12 Erythrocytapheresis is another strategy for lowering viscosity by removing red cells from the circulation.23 Although the effects of regional anesthesia on coagulation in polycythemic cyanotic CHD patients are unknown, general anesthetics and surgery are known to contribute to hypercoagulable states; perhaps another added benefit of regional blockade for such patients is the avoidance of some of these adverse hemorheological effects. At the same time, patients with significant polycythemia secondary to their cyanotic CHD should be considered at risk for increased bleeding, and should be evaluated by history and standard laboratory examinations, although this does not typically occur until hematocrits greater than those of the present patients are encountered.24Js The psychological benefits of regional anesthesia were important for these patients. McNamara noted that the attitude of the adult patient with CHD is often influenced by restricted and overprotected childhoods, and multiple contacts with hospitals and doctorsz6 With a history of multiple hospitalizations and intense medical care all of their lives, these patients were reluctant to allow themselves to become unconscious and “lose control” if they could avoid it. Regional anesthesia allowed them to remain conscious while small amounts of sedation provided anxiolysis. Spinal anesthesia, as an alternative, is less desirable, because of the rapid onset of sympathetic blockade, and is not as titratable as progressive epidural analgesia. Continuous spinal anesthesia, more recently available with microcatheter techniques, offers another option for the more gradual onset of sympathetic blockade.
EPIDURAL ANESTHESIA
IN HEART DISEASE
343
Both patients were monitored with an electrocardiogram, oscillometric blood pressure cuff, precordial stethoscope for breath and heart sounds, and a pulse oximeter. In order to support the SVR, particularly in patient 2 with tetralogy of Fallot and a systemic-to-pulmonary artery shunt, the authors were prepared to treat with phenylephrine, but found it unnecessary because S,Oz did not change significantly from baseline, and the patient’s mental status remained the same. Phenylephrine was the drug of choice as a directly acting vasoconstrictor in order to increase SVR, with specific cui-receptor, and no l3-adrenergic activity. For the same pharmacologic reasons, methoxamine would be an equivalent choice. Both patients received supplemental oxygen for its possi-
ble salutary effect on pulmonary vascular resistance, as well as for any contribution that it could make to an increased margin of safety. While sedation may contribute to hypercarbia with its potential for adversely affecting pulmonary vascular resistance and endogenous catecholamine elaboration, judicious conscious sedation was used without any apparent deleterious effects. Finally, air bubbles were avoided, and an air filter was used in the intravenous tubing.
ACKNOWLEDGMENT
The authors thank Dr Paul R. Hickey for his kind review and thoughtful
suggestions
about the manuscript.
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