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Intraoperative suspicion of phaeochromocytoma during elective coronary artery surgery
Case Report Intraoperative Suspicion Of Phaeochromocytoma During Elective Coronary Artery Surgery Sarah J. Bucknell, FRCS,David G. Hill, FRACS,FRCS,Morteza Mohajeri,
FRACS
Department of Cardiothoracic Surgery, Geelong Hospital, Geelong, Victoria
A patient with an unsuspected phaeochromocytoma survived elective coronary artery bypass grafting due to aggressive pharmacological therapy for episodes of severe hypertension during surgery. The favourable result was probably attributable to an early suspicion during surgery that a phaeochromocytoma may be present and the prompt commencement of aggressive pharmacological therapy. After tests which contlrmed the presence of the tumour, the patient underwent surgery to remove a phaeochromocytoma from the right adrenal gland. He recovered uneventfully, his blood pressure returning to normal. Surgery on an unprepared patient with a phaeochromocytoma is hazardous and carries a high mortality. (Asia Pacific Heart Journal l!TJ!Xl;7(2):125-128)
Introduction Phaeochromocytoma is a rare and potentially lethal catecholamine-secreting tumour usually arising in the adrenal medulla. Surgery in the presence of an undiagnosed phaeochromocytoma is extremely hazardous and associated with a high mortality.13 2 We report a patient in whom a phaeochromocytoma was suspected during coronary artery surgery due to a grossly labile systolic blood pressure requiring large doses of vasodilator therapy.
A blood test showed no cardiac-enzyme rise. Results of an angiogram revealed a greater than 50% stenosis at the ostium of his left main stem and an 80% stenosis of the mid portion of the right coronary artery. Left ventriculography was normal. The patient remained stable and pain-free on the heparin and GTN infusions. Coronary revascularisation was planned for the following week. During his preoperative in-patient stay he was normotensive at 120/70 mmHg except for 1 episode of hypertension reaching a systolic pressure of 190 mmHg which resolved spontaneously.
Case Report A 53-year-old, insulin-dependent diabetic male presented to the Emergency Department with a 24-hour history of recurrent chest pain. Postero-inferior ECG changes were found, and the patient was admitted to the Coronary Care Unit where he was subsequently stabilised on heparin and glyceryl trinitrate (GTN) infusions. He had no history of angina but did have a history of hyperlipidaemia and hypertension.
Induction of anaesthesia was achieved with propofol 1 mg/kg, fentanyl 25 yg/kg, pancuronium 0.15-0.2 mg/kg and clonidine 4 ug/kg.3 Anaesthesia was maintained with a stepped infusion of propofol at 5 mg/kg/hour for 10 min, 4 mg/kg/hour for a further 10 min and 3 mg/kg/hour thereafter.4 Arterial pressure was stable for the first 5 min postinduction, but the patient then developed frequent hypertensive surges with systolic pressures in excess of 200 mniHg.
His medications included atenolol, 50 mg once daily, captopril 6.25 mg once daily, insulin and aspirin. He had ceased smoking 30 cigarettes per day 3 weeks previously. He had no other significant medical history apart from 2 previous uneventful procedures for vasectomy and menisectomy under general anaesthesia.
A GTN infusion was commenced, and high doses were required from l-6 yg/kg/min to control the surges. Once cardiopulmonary bypass (CPB) was established, the mean arterial pressure remained high, and the systemic vascular resistance index was in excess of 1,500 dyn see-lcm-5. An infusion of sodium nitroprusside (SNP) was commenced, but infusion rates exceeding 5 ug/kg/min did not control the peaks of arterial pressure. Consequently, multiple bolus doses of 0.5 mg of phentolamine were required.
His heart was in sinus rhythm with a rate of 60 beats/min, and blood pressure was 120/70 mmHg. The results of a physical examination were unremarkable. The chest X-ray examination and results of blood screen and serum electrolytes results were within normal limits.
125
AsiaPacificHeartJ 1998;7(2)
Bucknell,Hill, Mohajeri Intraoperative
suspicion
of phaeochromocytoma
< HMHG)
H:IlIN) Fig. 1. A record of the patient’s systolic blood pressurein the intensive care unit for the first 5 hours. Three coronary artery bypass grafts were performed using intermittent aortic crossclamping with cold-blood cardioplegia and moderate cooling to 30°C. Total bypass time was 100 min, and crossclamp time was 47 min. The patient was weaned from CPB satisfactorily although the large swings in blood pressure persisted. After CPB, his arterial pressure remained extremely labile, with systolic pressures as low as 50 mmHg and surges exceeding 200 mmHg.
Discussion The incidence of phaeochromocytoma is 1 or 2 per 100,000. It represents a curable cause of approximately 0.1-l% of hypertension cases.5 It occurs sporadically in 88% of cases and in association with familial syndromes in the remainder: multiple endocrine neoplasia (MEN) syndrome IIa (4%) or IIb (2%), Von Hippel-Lindau disease (3%), neurofibromatosis (3%) and Carney’s syndrome ( 1%)6.
On transfer of the patient to the Intensive Care Unit, infusion of phentolamine was commenced, initially at a rate of 4 mg/hour and reducing to 2 mg/hour. The arterial pressure gradually stabilised within the normal range with a mean pressure of 80 mmHg (Fig. 1). The remainder of his postoperative course was uneventful. The phentolamine was changed to oral phenoxybenzamine once a normal diet was tolerated. On the second postoperative day, atenolol was added to the antihypertensive regime. Mild postural hypotension of 30 mmHg was observed, but no further paroxysms of hypertension were noted.
The majority of these neuroendocrine tumours occur in the adrenal medulla (80%), and the remainder, known as paragangliomas or chemodactomas, are scattered along the sympathetic chain, the Organ of Zuckerkandyl, the pericardium and in the posterior mediastinum. Approximately 10% are bilateral, usually in association with multiple endocrine neoplasia. About 85-90% are benign, although malignancy can be difficult to predict unless gross capsular invasion or metastases are present. Phaeochromocytomas can present a difficult clinical problem as patients present with a wide range of symptoms which mimic a variety of physiological and psychological conditions. The classical clinical history is one of paroxysmal headache, sweating and palpitations. The predominantly adrenaline secreting tumour produces symptoms of beta-adrenergic stimulation, namely paroxysmal hypertension, palpitations, sweating, headaches and anxiety. Symptoms tend to be less dramatic if noradrenaline secretion predominates, with sustained resistant hypertension being the main feature. A smaller proportion of patients present with other clinical features such as angina (5%), myocardial infarction (5%), hypertensive encephalopathy (5%), haematuria (5%) or subarachnoid haemorrhage (2%).7
A phaeochromocytoma was suspected, and a predominantly adrenaline-secreting tumour was confirmed on 24-hour urine analysis. The results were as follows: adrenaline 2,889 nmol/d (l-SO>, noradrenaline 1,068 nmol/d (l-780) and dopamine 1,223 nmol/d (2303,500). CT scan demonstrated a soft tissue mass measuring 3x4 cm and occupying the right adrenal gland. No lymphadenopathy or other intra-abdominal pathology was demonstrated (Fig. 2). He was discharged home 10 days after cardiac surgery and was prescribed atenolol, 50 mg twice daily, phenoxybenzamine, 40 mg twice daily, and aspirin.
The diagnosis can be confirmed biochemically in most patients by the measurement of catecholamines and their metabolites (vanillymandelic acid) in 24-hour urine collections. Assay of plasma catecholamine concentrations is helpful to determine the proportion of adrenaline and noradrenaline secreted. If the diagnosis is still equivocal, pharmacological tests may be useful. A suppression test using the centrally acting a2agonist, clonidine, is commonly used.8 This test is based
He was readmitted 3 weeks later, and resection of the tumour occupying the right adrenal gland was performed. Slight hypertensive surges occurred preoperatively but were less severe than observed previously. Histological examination of the specimen confirmed the presence of a phaeochromocytoma which showed no evidence of invasion. He made an uneventful recovery and was well at follow-up with a blood pressure of 120/70 mmHg.
126
Asia Pacific
Heart .I 1998;7(2) Intraoperative
suspicion
Bucknell, Hill, Mohajeri ofphaeochromocytom
prognosis. In 1951 Apgar reported a 50% mortality in the early postoperative period on patients with unsuspected phaeochromocytomas.* Mode of death in most cases is attributable to cardiovascular collapse and hypovolaemia.
on the rationale that autonomous secretion of catecholamines in phaeochromocytoma is not affected by clonidine whereas levels in hypertensive patients will be suppressed by clonidine’s central action. A test dose of 4.3 pg/kg of clonidine is given orally, and failure of suppression of plasma catecholamine concentrations indicates a positive result. This test has proven to be useful in discriminating phaeochromocytoma from other forms of hypertension.9 As in this case, the tumour is accurately located by CT scan in 95% of patients. Isotope scanning using metaiodobenzylguanidine (MIBG) can be helpful for locating recurrent or ectopic tumour. With optimal management the prognosis is excellent. It is important that all patients are adequately hydrated and rendered normotensive with complete alpha and beta blockade for at least 2 weeks prior to planned surgical resection. In these circumstances the mortality from elective surgery should be less than 2%. Approximately 80% of patients will become normotensive, and recurrence occurs in less than lo%.5 Beta blockade is contraindicated prior to alpha blockade because if betamediated vasodilatation is blocked, unopposed vasoconstriction mediated by the alpha receptors could produce severe surges of hypertension.5JO
Recent reports 11512have suggested that severe intraoperative haemodynamic instability could be a clue to the presence of an undiagnosed phaeochromocytoma and should prompt early aggressive pharmacological therapy. It is advisable to terminate surgery, transfer the patient to an Intensive Care Unit for the early postoperative period, and postpone further surgery until the patient is adequately investigated and prepared. Two previous cases of unsuspected phaeochromocytoma in patients undergoing cardiac surgery have been described. In the first case the patient was stable intraoperatively, and the diagnosis was not suspected until persistent hypertension with fluctuations from 50 to 200 mmHg were noted in the postoperative period.13 Brown l4 described a case in which severe paroxysmal hypertension occurred on separation from CPB which was resistant to conventional antihypertensive therapy. One previous episode of hypertension coinciding with tracheal intubation had occurred but otherwise the patient had remained stable whilst on bypass. Fentanyl, enflurane, morphine, diazepam and droperidol were used to maintain
Surgery in a patient with an undiagnosed phaeochromocytoma is hazardous and has a poor
127
Asia Pacific
Heart J 1998;7(2) Intraoperative
anaesthesia. After bypass there were frequent surges of hypertension. Systolic peaks in excess of 200 mmHg were not controlled by large doses of hydralazine and propranolol. A phaeochromocytoma was suspected due to the extreme elevations in blood pressure, and phentolamine was commenced which controlled the hypertensive surges. The authors postulated that highdose fentanyl may have had a beneficial effect due to its alpha-blocking effect on vascular smooth muscle. They suggested that droperidol and propranolol may have exacerbated the hypertension and that the stress of CPB and hypothermia would have increased tumour catecholamine secretion.
suspicion
Bucknell, Hill, Mohajeri of phaeochromocytoma
the early use of phentolamine which could have contributed to the favourable outcome by reducing systemic vascular resistance and allowing restoration of intravascular volume Conclusion Our case demonstrates that a patient with an unsuspected phaeochromocytoma can survive elective coronary artery bypass grafting. The favourable result is likely to be attributable to early suspicion in the intraoperative period and the prompt commencement of aggressive pharmacological therapy. References 1.
In our patient, the surges of hypertension started soon after induction of anaesthesia. The use of total intravenous anaesthesia with fentanyl and propofol may have had a beneficial effect as the 2 drugs will tend to produce some reduction in arterial pressure due to their action on vascular smooth muscle.4Js
2. 3.
The alpha agonist clonidine is routinely used in all our patients regardless of preoperative blood pressure to protect renal function. Clonidine is thought to produce this effect by reducing the sympathetic response and so limiting stress-induced renal damage during CPB.3 A dose of 4 pglkg is infused slowly after induction and prior to CPB. This is a similar dose to that used in the previously described clonidine suppression test, presumably giving a positive result as the paroxysmal hypertensive surges would indicate catecholamine secretion had not been suppressed. Clonidine has moderate haemodynamic effects, decreasing mean arterial pressure (MAP) by a maximum of 20% and heart rate by a maximum of 12% due to its action on the alpha receptors in the medul1a.r” A brief rise in blood pressure is sometimes encountered after intravenous administration due to direct stimulation of the receptors in the arterioles but slow infusion minimises signs of peripheral alphaadrenergic stimulation.17 It is possible that the administration of clonidine could have contributed to the hypertension and the early intraoperative presentation. However, it is more likely that the administration of this dose of clonidine reduced the hypertensive response by modifying the vasoconstriction response to catecholamine secretion. The patient had also been treated with a beta blocker preoperatively. As mentioned previously this too will accentuate the degree of hypertension as beta-mediated vasodilatation is blocked.
4.
5. 6.
7.
8. 9.
10. 11. 12.
13.
14.
15. 16.
17.
Due to the severity and paroxysmal nature of the hypertension and its resistance to conventional antihypertensive therapy, a phaeochromocytoma was suspected whilst the patient was on CPB. This prompted
18.
128
Apgar V, Papper EM. Phaeochromocytoma: anaesthetic management during surgical treatment. Arch Surg 1951;62:634-46. Scott HW, Oates JA, Nies AS, et al. Phaeochromocytoma: diagnosis and management. Ann Surg 1976;183:587-92. Kulka PJ, Tryba MT, Zenz M. Preoperative c&adrenergic receptor agonists prevent the deterioration of renal function after cardiac surgery: results of a randomised controlled trial. Crit Care Med 1996;24(6):947-52. Manara AR, Monk CR, Bolsin SN, Prys-Roberts C. Total IV anaesthesia with propofol andalfentanil for coronary artery bypass grafting. B J Anaes 1991;66:716-18. Foo M, Burton BJL, Ahmed R. Phaeochromocytoma. B J Hosp Med 1995;7:318-21. Orchard T, Grant CS, Heerden JA, Weaver A. Phaeochromocytoma: continuing evolution of surgical therapy. Surg 1993;6:1153-9. Beatty OL, Russell CFJ, Kennedy L, Hadden DR, Kennedy TL, Atkinson AB. Phaeochromocytoma in Northern Ireland: a 21-year review. Eur J Surg 1996;162:695-702. Wetheral, Ledingham, Warfell. Oxford Textbook of Medicine (3rd ed). New York Oxford University Press, 1996, vol. 2. Bachmann AW, Gordon RD. Clonidine suppression test reliably differentiates phaeochromocytoma from essential hypertension. Clin Exp Pharmacol Physiol 1991;18:275-7. Kaplan NM, Swain CT. Diagnosis and treatment of phaeochromocytoma. UpToDate 1997. Wooster DL, Mitchell RI. Unsuspected phaeochromocytoma presenting during surgery. Can Anaesth Sot J 1981;28:471-4. Voros DC, Smymiotis B, Argyra E, Vadalouka A, Siafaka I, Papadimitriou J. Undiagnosed phaeochromocytomas in the perioperative period. Eur J Surg 1995;162:985-7. Lefrak EA, MacManus Q, Ross P. Phaeochromocytoma as a cause of hypertension after coronary bypass. Virginia Med J 1983; 11 0: 183-5. Brown P, Caplan PA. Recognition of an unsuspected phaeochromocytoma during elective coronary artery bypass surgery. Can Anaesth Sot J 1986;33(6):785-9. Lunn JN. Lecture notes on anaesthetics (4th ed). Oxford: Blackwell, 1991;51-4. Taittonen M, Kirvela 0, Aantaa R, Kanto J. Cardiovascular and metabolic responses to clonidine and midazolam premeditation. Eur J Anaesth 1997;14:190-6. Katzung BG. Basic and clinical pharmacology (4th ed). Norwalk CA: Appleton &Lange, 1989;124-125. Proye CAG, Vix M, Jansson S, Tisell LE, Dralle H, Hiller W. “The” phaeochromocytoma: a benign, intra-adrenal, hypertensive, sporadic, unilateral tumour. Does it exist? World J Surg 1994:18:467-72.
FRACS
Department of Cardiothoracic Surgery, Geelong Hospital, Geelong, Victoria
A patient with an unsuspected phaeochromocytoma survived elective coronary artery bypass grafting due to aggressive pharmacological therapy for episodes of severe hypertension during surgery. The favourable result was probably attributable to an early suspicion during surgery that a phaeochromocytoma may be present and the prompt commencement of aggressive pharmacological therapy. After tests which contlrmed the presence of the tumour, the patient underwent surgery to remove a phaeochromocytoma from the right adrenal gland. He recovered uneventfully, his blood pressure returning to normal. Surgery on an unprepared patient with a phaeochromocytoma is hazardous and carries a high mortality. (Asia Pacific Heart Journal l!TJ!Xl;7(2):125-128)
Introduction Phaeochromocytoma is a rare and potentially lethal catecholamine-secreting tumour usually arising in the adrenal medulla. Surgery in the presence of an undiagnosed phaeochromocytoma is extremely hazardous and associated with a high mortality.13 2 We report a patient in whom a phaeochromocytoma was suspected during coronary artery surgery due to a grossly labile systolic blood pressure requiring large doses of vasodilator therapy.
A blood test showed no cardiac-enzyme rise. Results of an angiogram revealed a greater than 50% stenosis at the ostium of his left main stem and an 80% stenosis of the mid portion of the right coronary artery. Left ventriculography was normal. The patient remained stable and pain-free on the heparin and GTN infusions. Coronary revascularisation was planned for the following week. During his preoperative in-patient stay he was normotensive at 120/70 mmHg except for 1 episode of hypertension reaching a systolic pressure of 190 mmHg which resolved spontaneously.
Case Report A 53-year-old, insulin-dependent diabetic male presented to the Emergency Department with a 24-hour history of recurrent chest pain. Postero-inferior ECG changes were found, and the patient was admitted to the Coronary Care Unit where he was subsequently stabilised on heparin and glyceryl trinitrate (GTN) infusions. He had no history of angina but did have a history of hyperlipidaemia and hypertension.
Induction of anaesthesia was achieved with propofol 1 mg/kg, fentanyl 25 yg/kg, pancuronium 0.15-0.2 mg/kg and clonidine 4 ug/kg.3 Anaesthesia was maintained with a stepped infusion of propofol at 5 mg/kg/hour for 10 min, 4 mg/kg/hour for a further 10 min and 3 mg/kg/hour thereafter.4 Arterial pressure was stable for the first 5 min postinduction, but the patient then developed frequent hypertensive surges with systolic pressures in excess of 200 mniHg.
His medications included atenolol, 50 mg once daily, captopril 6.25 mg once daily, insulin and aspirin. He had ceased smoking 30 cigarettes per day 3 weeks previously. He had no other significant medical history apart from 2 previous uneventful procedures for vasectomy and menisectomy under general anaesthesia.
A GTN infusion was commenced, and high doses were required from l-6 yg/kg/min to control the surges. Once cardiopulmonary bypass (CPB) was established, the mean arterial pressure remained high, and the systemic vascular resistance index was in excess of 1,500 dyn see-lcm-5. An infusion of sodium nitroprusside (SNP) was commenced, but infusion rates exceeding 5 ug/kg/min did not control the peaks of arterial pressure. Consequently, multiple bolus doses of 0.5 mg of phentolamine were required.
His heart was in sinus rhythm with a rate of 60 beats/min, and blood pressure was 120/70 mmHg. The results of a physical examination were unremarkable. The chest X-ray examination and results of blood screen and serum electrolytes results were within normal limits.
125
AsiaPacificHeartJ 1998;7(2)
Bucknell,Hill, Mohajeri Intraoperative
suspicion
of phaeochromocytoma
< HMHG)
H:IlIN) Fig. 1. A record of the patient’s systolic blood pressurein the intensive care unit for the first 5 hours. Three coronary artery bypass grafts were performed using intermittent aortic crossclamping with cold-blood cardioplegia and moderate cooling to 30°C. Total bypass time was 100 min, and crossclamp time was 47 min. The patient was weaned from CPB satisfactorily although the large swings in blood pressure persisted. After CPB, his arterial pressure remained extremely labile, with systolic pressures as low as 50 mmHg and surges exceeding 200 mmHg.
Discussion The incidence of phaeochromocytoma is 1 or 2 per 100,000. It represents a curable cause of approximately 0.1-l% of hypertension cases.5 It occurs sporadically in 88% of cases and in association with familial syndromes in the remainder: multiple endocrine neoplasia (MEN) syndrome IIa (4%) or IIb (2%), Von Hippel-Lindau disease (3%), neurofibromatosis (3%) and Carney’s syndrome ( 1%)6.
On transfer of the patient to the Intensive Care Unit, infusion of phentolamine was commenced, initially at a rate of 4 mg/hour and reducing to 2 mg/hour. The arterial pressure gradually stabilised within the normal range with a mean pressure of 80 mmHg (Fig. 1). The remainder of his postoperative course was uneventful. The phentolamine was changed to oral phenoxybenzamine once a normal diet was tolerated. On the second postoperative day, atenolol was added to the antihypertensive regime. Mild postural hypotension of 30 mmHg was observed, but no further paroxysms of hypertension were noted.
The majority of these neuroendocrine tumours occur in the adrenal medulla (80%), and the remainder, known as paragangliomas or chemodactomas, are scattered along the sympathetic chain, the Organ of Zuckerkandyl, the pericardium and in the posterior mediastinum. Approximately 10% are bilateral, usually in association with multiple endocrine neoplasia. About 85-90% are benign, although malignancy can be difficult to predict unless gross capsular invasion or metastases are present. Phaeochromocytomas can present a difficult clinical problem as patients present with a wide range of symptoms which mimic a variety of physiological and psychological conditions. The classical clinical history is one of paroxysmal headache, sweating and palpitations. The predominantly adrenaline secreting tumour produces symptoms of beta-adrenergic stimulation, namely paroxysmal hypertension, palpitations, sweating, headaches and anxiety. Symptoms tend to be less dramatic if noradrenaline secretion predominates, with sustained resistant hypertension being the main feature. A smaller proportion of patients present with other clinical features such as angina (5%), myocardial infarction (5%), hypertensive encephalopathy (5%), haematuria (5%) or subarachnoid haemorrhage (2%).7
A phaeochromocytoma was suspected, and a predominantly adrenaline-secreting tumour was confirmed on 24-hour urine analysis. The results were as follows: adrenaline 2,889 nmol/d (l-SO>, noradrenaline 1,068 nmol/d (l-780) and dopamine 1,223 nmol/d (2303,500). CT scan demonstrated a soft tissue mass measuring 3x4 cm and occupying the right adrenal gland. No lymphadenopathy or other intra-abdominal pathology was demonstrated (Fig. 2). He was discharged home 10 days after cardiac surgery and was prescribed atenolol, 50 mg twice daily, phenoxybenzamine, 40 mg twice daily, and aspirin.
The diagnosis can be confirmed biochemically in most patients by the measurement of catecholamines and their metabolites (vanillymandelic acid) in 24-hour urine collections. Assay of plasma catecholamine concentrations is helpful to determine the proportion of adrenaline and noradrenaline secreted. If the diagnosis is still equivocal, pharmacological tests may be useful. A suppression test using the centrally acting a2agonist, clonidine, is commonly used.8 This test is based
He was readmitted 3 weeks later, and resection of the tumour occupying the right adrenal gland was performed. Slight hypertensive surges occurred preoperatively but were less severe than observed previously. Histological examination of the specimen confirmed the presence of a phaeochromocytoma which showed no evidence of invasion. He made an uneventful recovery and was well at follow-up with a blood pressure of 120/70 mmHg.
126
Asia Pacific
Heart .I 1998;7(2) Intraoperative
suspicion
Bucknell, Hill, Mohajeri ofphaeochromocytom
prognosis. In 1951 Apgar reported a 50% mortality in the early postoperative period on patients with unsuspected phaeochromocytomas.* Mode of death in most cases is attributable to cardiovascular collapse and hypovolaemia.
on the rationale that autonomous secretion of catecholamines in phaeochromocytoma is not affected by clonidine whereas levels in hypertensive patients will be suppressed by clonidine’s central action. A test dose of 4.3 pg/kg of clonidine is given orally, and failure of suppression of plasma catecholamine concentrations indicates a positive result. This test has proven to be useful in discriminating phaeochromocytoma from other forms of hypertension.9 As in this case, the tumour is accurately located by CT scan in 95% of patients. Isotope scanning using metaiodobenzylguanidine (MIBG) can be helpful for locating recurrent or ectopic tumour. With optimal management the prognosis is excellent. It is important that all patients are adequately hydrated and rendered normotensive with complete alpha and beta blockade for at least 2 weeks prior to planned surgical resection. In these circumstances the mortality from elective surgery should be less than 2%. Approximately 80% of patients will become normotensive, and recurrence occurs in less than lo%.5 Beta blockade is contraindicated prior to alpha blockade because if betamediated vasodilatation is blocked, unopposed vasoconstriction mediated by the alpha receptors could produce severe surges of hypertension.5JO
Recent reports 11512have suggested that severe intraoperative haemodynamic instability could be a clue to the presence of an undiagnosed phaeochromocytoma and should prompt early aggressive pharmacological therapy. It is advisable to terminate surgery, transfer the patient to an Intensive Care Unit for the early postoperative period, and postpone further surgery until the patient is adequately investigated and prepared. Two previous cases of unsuspected phaeochromocytoma in patients undergoing cardiac surgery have been described. In the first case the patient was stable intraoperatively, and the diagnosis was not suspected until persistent hypertension with fluctuations from 50 to 200 mmHg were noted in the postoperative period.13 Brown l4 described a case in which severe paroxysmal hypertension occurred on separation from CPB which was resistant to conventional antihypertensive therapy. One previous episode of hypertension coinciding with tracheal intubation had occurred but otherwise the patient had remained stable whilst on bypass. Fentanyl, enflurane, morphine, diazepam and droperidol were used to maintain
Surgery in a patient with an undiagnosed phaeochromocytoma is hazardous and has a poor
127
Asia Pacific
Heart J 1998;7(2) Intraoperative
anaesthesia. After bypass there were frequent surges of hypertension. Systolic peaks in excess of 200 mmHg were not controlled by large doses of hydralazine and propranolol. A phaeochromocytoma was suspected due to the extreme elevations in blood pressure, and phentolamine was commenced which controlled the hypertensive surges. The authors postulated that highdose fentanyl may have had a beneficial effect due to its alpha-blocking effect on vascular smooth muscle. They suggested that droperidol and propranolol may have exacerbated the hypertension and that the stress of CPB and hypothermia would have increased tumour catecholamine secretion.
suspicion
Bucknell, Hill, Mohajeri of phaeochromocytoma
the early use of phentolamine which could have contributed to the favourable outcome by reducing systemic vascular resistance and allowing restoration of intravascular volume Conclusion Our case demonstrates that a patient with an unsuspected phaeochromocytoma can survive elective coronary artery bypass grafting. The favourable result is likely to be attributable to early suspicion in the intraoperative period and the prompt commencement of aggressive pharmacological therapy. References 1.
In our patient, the surges of hypertension started soon after induction of anaesthesia. The use of total intravenous anaesthesia with fentanyl and propofol may have had a beneficial effect as the 2 drugs will tend to produce some reduction in arterial pressure due to their action on vascular smooth muscle.4Js
2. 3.
The alpha agonist clonidine is routinely used in all our patients regardless of preoperative blood pressure to protect renal function. Clonidine is thought to produce this effect by reducing the sympathetic response and so limiting stress-induced renal damage during CPB.3 A dose of 4 pglkg is infused slowly after induction and prior to CPB. This is a similar dose to that used in the previously described clonidine suppression test, presumably giving a positive result as the paroxysmal hypertensive surges would indicate catecholamine secretion had not been suppressed. Clonidine has moderate haemodynamic effects, decreasing mean arterial pressure (MAP) by a maximum of 20% and heart rate by a maximum of 12% due to its action on the alpha receptors in the medul1a.r” A brief rise in blood pressure is sometimes encountered after intravenous administration due to direct stimulation of the receptors in the arterioles but slow infusion minimises signs of peripheral alphaadrenergic stimulation.17 It is possible that the administration of clonidine could have contributed to the hypertension and the early intraoperative presentation. However, it is more likely that the administration of this dose of clonidine reduced the hypertensive response by modifying the vasoconstriction response to catecholamine secretion. The patient had also been treated with a beta blocker preoperatively. As mentioned previously this too will accentuate the degree of hypertension as beta-mediated vasodilatation is blocked.
4.
5. 6.
7.
8. 9.
10. 11. 12.
13.
14.
15. 16.
17.
Due to the severity and paroxysmal nature of the hypertension and its resistance to conventional antihypertensive therapy, a phaeochromocytoma was suspected whilst the patient was on CPB. This prompted
18.
128
Apgar V, Papper EM. Phaeochromocytoma: anaesthetic management during surgical treatment. Arch Surg 1951;62:634-46. Scott HW, Oates JA, Nies AS, et al. Phaeochromocytoma: diagnosis and management. Ann Surg 1976;183:587-92. Kulka PJ, Tryba MT, Zenz M. Preoperative c&adrenergic receptor agonists prevent the deterioration of renal function after cardiac surgery: results of a randomised controlled trial. Crit Care Med 1996;24(6):947-52. Manara AR, Monk CR, Bolsin SN, Prys-Roberts C. Total IV anaesthesia with propofol andalfentanil for coronary artery bypass grafting. B J Anaes 1991;66:716-18. Foo M, Burton BJL, Ahmed R. Phaeochromocytoma. B J Hosp Med 1995;7:318-21. Orchard T, Grant CS, Heerden JA, Weaver A. Phaeochromocytoma: continuing evolution of surgical therapy. Surg 1993;6:1153-9. Beatty OL, Russell CFJ, Kennedy L, Hadden DR, Kennedy TL, Atkinson AB. Phaeochromocytoma in Northern Ireland: a 21-year review. Eur J Surg 1996;162:695-702. Wetheral, Ledingham, Warfell. Oxford Textbook of Medicine (3rd ed). New York Oxford University Press, 1996, vol. 2. Bachmann AW, Gordon RD. Clonidine suppression test reliably differentiates phaeochromocytoma from essential hypertension. Clin Exp Pharmacol Physiol 1991;18:275-7. Kaplan NM, Swain CT. Diagnosis and treatment of phaeochromocytoma. UpToDate 1997. Wooster DL, Mitchell RI. Unsuspected phaeochromocytoma presenting during surgery. Can Anaesth Sot J 1981;28:471-4. Voros DC, Smymiotis B, Argyra E, Vadalouka A, Siafaka I, Papadimitriou J. Undiagnosed phaeochromocytomas in the perioperative period. Eur J Surg 1995;162:985-7. Lefrak EA, MacManus Q, Ross P. Phaeochromocytoma as a cause of hypertension after coronary bypass. Virginia Med J 1983; 11 0: 183-5. Brown P, Caplan PA. Recognition of an unsuspected phaeochromocytoma during elective coronary artery bypass surgery. Can Anaesth Sot J 1986;33(6):785-9. Lunn JN. Lecture notes on anaesthetics (4th ed). Oxford: Blackwell, 1991;51-4. Taittonen M, Kirvela 0, Aantaa R, Kanto J. Cardiovascular and metabolic responses to clonidine and midazolam premeditation. Eur J Anaesth 1997;14:190-6. Katzung BG. Basic and clinical pharmacology (4th ed). Norwalk CA: Appleton &Lange, 1989;124-125. Proye CAG, Vix M, Jansson S, Tisell LE, Dralle H, Hiller W. “The” phaeochromocytoma: a benign, intra-adrenal, hypertensive, sporadic, unilateral tumour. Does it exist? World J Surg 1994:18:467-72.