Interventional radiology
- a review
K. Thomson Consultant Radiologist, Department of Radiology, The Royal Melbourne Hospital, Vic.
INTRODUCTION Over the past 20 years a quiet revolution has occurred in medicine; the growth of interventional radiology. This name was chosen because of the prior use of therapeutic radiology by the radiation therapists and because radiological techniques, principally those of angiography, are used. At first, only those patients unsuitable for conventional treatment were submitted to the radiologist, but as experience grew and the results improved, in selected cases interventional radiology became the prime choice of treatment. A measure of the acceptance of interventional radiology is the number of surgeons who now perform interventional procedures. The major benefits of interventional radiology are: 0 reduction in morbidity; 0 wide availability; 0 reduction in hospitalisation costs. The original principles on which interventional radiology was based were the use of the Seldinger technique for access and local anaesthesia. More recently endoscopes have expanded the horizons of interventional therapy and the term minimally invasive therapy more correctly describes this type of treatment. Entrepreneurs in these techniques have caught the imagination of the public media and many of the techniques such as laser angioplasty have been widely publicised with the result that some patients demand an interventional procedure when a more conventional procedure is indicated. These procedures require significant ability with three dimensional imaging and with the devices used to perform the techniques. As a result the complication rates are mostly directly related to the experience of the person performing them. One factor, independent of the operator, which has caused reduction of complication rates, has been the introduction of nonionic iodinated radiographic contrast media. The nonionic compounds have a lower osmolality than conven-
tional ionic contrast media and are about five times less likely to cause minor and major contrast media reactions.’
ANGIOPLASTY In spite of the advances in angioplasty and devices in the past few years there is still a considerable place for conventional arterial surgery as only about 30% of lower limb arterial lesions are suitable for angioplasty . If a localised and symptomatic arterial lesion is found in the distal aorta or lower limbs then balloon angioplasty is indicated as a first choice. A prospective analysis of 984 consecutive lesions by Johnston er al. showed an initial success rate of 89% and a five year patency rate of 48%.’ Four variables were found to be significant predictors of success. These were the indication for the angioplasty (claudication vs salvage), the site of the angioplasty (common iliac vs other), severity of the lesion (stenosis vs occlusion) and peripheral run-off (good vs poor). Almost all lesions in the lower limbs suitable for angioplasty are readily detected with a careful clinical examination. Surgical back-up of all angioplasties is essential as occasionally complications may arise which may require surgical intervention. Some surgeons advocate performance of angioplasty only in an operating theatre setting, but in the Royal Melbourne Hospital’s experience of over 2000 peripheral angioplasties this is not warranted in terms of patient care or of cost. The type of treatment required can only be determined after angiography (Figure 1). The major problem of balloon angioplasty is recurrence of stenosis. This occurs in about 25-30% of angioplasties’ and has stimulated the development of alternative or adjunctive measures. The most widely known of these is the thermal Nd-YAG laser. The laser energy is used to heat a metal tip on the laser fibre to 500 degrees C and the hot tip burns a hole through
Reprint requests to: Dr K. Thomson, Consulant Radiologist, Department of Radiology, The Royal Melbourne Hospital P.O., Parkville, VIC. 3050, Australia.
902
Aust NZ J Med 1991; 21
THOMSON
f?1 Puncture Site Dbs Vascular ObSeIval~OnS
Clin~cal Follawup -readmill Testing E x e m s 8 program Slop Smoking Anliplatelet Drugs
1
Fipre 1: A flowchart of suggested actions prior to angioplasty of the lower limbs.
the atheroma. The thermal laser requires a subsequent balloon angioplasty but it is claimed that much higher long term patency rates are produced by the laser and longer occluded segments can be treated su~cessfully.~ Overseas controversy rages about the place of laser a n g i ~ p l a s t yThis . ~ is in part due to the lack of prospective controlled trials and the rapid advances in balloon and wire guide technology over the past few years. A major Australian trial of laser angioplasty is now underway in New South Wales to investigate long term patency for laser assisted angioplasty and the initial report of an American prospective trial showed that initial success was independent of whether the laser or a wire guide was used.6 The Excimer laser operates at a lower wavelength and produces a photoablative effect instead of charring by heat. In theory the Excimer ablates the atheroma producing a clean cut with less thermal damage to the normal arterial wall. Clinical trials of the Excimer are only just beginning. Other wavelengths of light are under investigation but it is likely that, unless there are major developments in laser technology, the use of lasers for treatment of atheroma will be limited to photoablative recanalisation of short occluded segments which cannot be opened by other percutaneous means. Atherectomy devices which remove the atheroma directly are claimed to have longer patency rates and INTERVENTIONAL RADIOLOGY - A REVIEW
Figure 2: TEC atherectomy of the tibia1 arteries performed for continuing claudication some months after a femoropopliteal vein bypass (arrow). (a) The anterior tibial artery is stenosed and the posterior tibial trunk is occluded. (b) Restoration of a good lumen in both vessels after the TEC catheter has been passed. Foot pulses were normal after this procedure.
lower embolic complications than balloon angioplasty alone (Figure 2(a), (2b)). Initial results show similar complications and restenosis to balloon angioplasty.' Transluminal angioplasty for renal artery stenosis offers the hope that antihypertensive medication can be reduced or ceased and that any progression of atherosclerosis as a result of the hypertension will be halted. Results in atherosclerotic disease arc poor when 903 Aust NZ J Med 1991; 21
Figure 4: Palmaz articulated stent 6 months after placement. The abdominal aorta and both renal arteries have been opened along their posterior aspects. (The patient died of coronary artery disease). The aortic ends of the stents were intentionally placed to project slightly into the aorta. The neointimal lining of the stents is quite smooth and free of thrombus and the steel mesh is almost completely covered except at the aortic end.
Figure 3: Palmaz Stent in abdominal aortic stenosis. (a) A
high grade stenosis of the abdominal aorta in a young obese woman. A previous attempt at surgical bypass had failed. (6) Angiographic result after balloon angioplasty and insertion of a Palmaz s e n t dilated to a diameter of 10 mm. She has been asymptomatic for the past year. Note the extensive atherosclerosis in the renal arteries.
accidents within one year of treatment. Careful clinical follow-up and treatment for atherosclerosis is required in these patients even when the renal angioplasty has been radiologically 'successful'. Treatment of acute coronary thrombosis by direct arterial infusion has been largely replaced by intravenous therapy for reasons of cost and practicality but in the lower limbs there is still a place for this method of treatment as intrathrombus injections of thrombolytics may recanalise even chronic occlusions. Almost always there is an underlying lesion which requires further treatment by balloon or another method. If the viability of the leg is precarious, then there may not be sufficient time for thrombolysis and urgent embolectomy is indicated. Lammer et aL'O reported 81% cumulative patency at two years after thrombolysis and angioplasty in 107 long (mean length 12.5 cm) occluded arterial segments. Should the balloon dilatation fail to establish a satisfactory lumen then an endovascular stent may be inserted percutaneously to resist the elastic recoil of the arterial wall and hold back dissection flaps and loose fragments of atheroma against the wall." The stents are of two types; balloon-expandable or selfexpanding. Either type may be rigid or flexible. Comparison of each type has not been made. Experience in 30 iliac stent placements at the Royal Melbourne Hospital with up to 18 months' follow-up has shown only one restenosis (not at the site of the stent) and two cases of peripheral embolisation. The stent offers increased patency in angioplasty of occluded segments" and also in the aorta where elastic recoil is more likely after angioplasty (Figure 3).
compared with results in other types of stenoses.8 Using the same criteria as would be applied to a new antihypertensive drug a review of 23 cases by Grimm et aL9 showed only two of six patients with fibromuscular disease were considered cured. Of the three patients with atherosclerotic stenoses who were considered improved all developed cerebrovascular 904 Aust NZ J Med 1991; 2 1
THOMSON
The availability of stents has also made renal angioplasty more widely available as restenosis of lesions at the renal artery orifice within six months after balloon dilatation has been reported to be between 80% and 100%.'* Stents appear ideal as a means to overcome this problem but it remains to be seen if the intimal covering which forms on all stents will reduce the renal artery lumen significantly or not (Figure 4). A worldwide multicentre trial of balloon-expandable renal artery stents is currently underway. The complications of peripheral angioplasty are listed in the angioplasty flowchart. About 2% of patients will require surgery after a balloon angioplasty. The most common reasons for surgery are peripheral embolism and acute occlusion of the dilated arterial segment. The worst complication is to advance a patient from simple claudication to rest pain or limb salvage as a result of a failed angioplasty. Multiple small emboli cause the syndrome of 'trash foot' which may result in amputation for unremitting ischaemia. Coronary artery angioplasty suffers from the same restenosis problems as angioplasty elsewhere. Lasers, atherectomy devices and stents are also being investigated in the coronary circulation. Coronary angioplasty has been increasing far faster than lower limb angioplasty and the indications for coronary angioplasty depend somewhat on the aggression and expertise of the cardiologist concerned. For multivessel angioplasty, a clinical success rate of 95%, with emergency surgery in 2.870, myocardial infarction in 3.0% and hospital death rate of 0.4% has been reported.I3 Similar or better results should be expected for simpler lesions. Suitable lesions for coronary angioplasty are: 0 Proximal severe (>70%) stenosis of one vessel; 0 recent occlusion of a single vessel; 0 severe (>70%) stenosis of two major vessels; 0 symptomatic restenosis of prior angioplasty; 0 residual stenosis post thrombolytic therapy; 0 coronary graft stenosis; 0 single vessel occlusion during myocardial infarction; multiple discrete stenoses in a single vessel. Lesions which have a high risk or a low chance of success are: 0 Left main stem stenoses or equivalent; 0 chronic occlusions (? try laser); 0 multiple stenoses in multiple vessels with a large amount of myocardium at risk. The problems of dissection and perforation are more serious in the coronary circulation and the expertise required for good results is only maintained with a large continuing experience. Early results listed by the National Heart, Lung and Blood Institute PTCA RegistryI4 indicated a complication rate overall of 2 1.1% with coronary dissection, occlusion or INTERVENTIONAL RADIOLOGY
- A REVIEW
myocardial infarction in 10% of the patients and death in 0.9%.Current results are much better than this and our own expectation is an infarction rate of less than 5%. A cardiac bypass team on standby and a counter pulsation aortic balloon pump are necessary for effective and safe management of complications. Aortic valvuloplasty is used for high risk patients who are generally old, frail and unfit for aortic replacement surgery. This procedure is still being evaluated. Letac el ~ 1 . 'reported ~ that in 144 patients who had aortic valvuloplasty, there were 24 deaths in the followup period (mean eight months) but that 84% of the survivors had good clinical improvement. Most of the deaths were due to existing cardiac disease. The aim of aortic valvuloplasty should be to increase the aortic valve area as much as possible rather than to just reduce the peak to peak aortic valve gradient. Pulmonary valvuloplasty for congenital stenosis is a useful procedure and has a high success rate.I6 In a series of 75 patients including three neonates with critical pulmonary valve stenosis, the mean pulmonary valve gradient was reduced significantly after angioplasty with lasting clinical and objective improvement.
ARTERIAL EMBOLOTHERAPY Control of haemorrhage is the most common indication for transcatheter occlusion. New catheter technology and occlusion devices have made this procedure easier." Superselective embolism is used for pelvic or abdominal bleeding after trauma, for uncontrolled bleeding from the nose and for bleeding resulting from operative procedures or biopsy of deep organs. Because the embolism is superselective, tissue damage from the occlusion is minimised. The type of material injected depends on the catheter size and the desired effect. For example a detachable balloon is the only device which can be tried in a number of positions before permanent occlusion, and for complete capillary occlusion a liquid agent is desirable. Some of the materials commonly used are: 0 Collagen paste; gelfoam or collagen pieces; wireguide and dacron coils; detachable balloons; 0 liquid occluders (silicones, glues, irritants). Angiography is useful in localising gastrointestinal bleeding if the patient is bleeding at the time of the angiogram at a rate of 0.5 mLlminute or more." Often the bleeding has stopped at the time a patient produces a malena stool. Low rate or intermittent bleeding is best localised by nuclear medicine techniques using labelled red cells (Figure 5). Control of gastrointestinal bleeding by vessel occlusion is generally recommended only in the stomach and first part of the d u ~ d e n u m . ' ~ The multiple arteries supplying the stomach protect Aust NZ J Med 1991; 21
905
1
Gastro-Intestinal Bleeding
I
Blood replacement
. Nudebr Medklno Scan
Anniogrsphy
BIwdInQ Sne Found
Superseleotive Embolisation
Pitressin Infusion
Eleclive C0rrl)ctive
Emergency
Figure 5: A flowchart for the management of gastrointestinal bleeding by interventional radiology.
it from ischaemia. In the remainder of the bowel, embolisation of an artery may cause necrosis or late stenosis of the ischaemic segment. Sebrechts and BooksteinZopresented a series of 28 patients who had embolotherapy for lower gastrointestinal haemorrhage. They Controlled the bleeding in 26 patients (93%)and found mucosal or transmural infarction in only three patients at the time of bowel resection one to four days later. In the remainder of the bowel, control of haemorrhage can be achieved by ultra-low dose (
- a review
K. Thomson Consultant Radiologist, Department of Radiology, The Royal Melbourne Hospital, Vic.
INTRODUCTION Over the past 20 years a quiet revolution has occurred in medicine; the growth of interventional radiology. This name was chosen because of the prior use of therapeutic radiology by the radiation therapists and because radiological techniques, principally those of angiography, are used. At first, only those patients unsuitable for conventional treatment were submitted to the radiologist, but as experience grew and the results improved, in selected cases interventional radiology became the prime choice of treatment. A measure of the acceptance of interventional radiology is the number of surgeons who now perform interventional procedures. The major benefits of interventional radiology are: 0 reduction in morbidity; 0 wide availability; 0 reduction in hospitalisation costs. The original principles on which interventional radiology was based were the use of the Seldinger technique for access and local anaesthesia. More recently endoscopes have expanded the horizons of interventional therapy and the term minimally invasive therapy more correctly describes this type of treatment. Entrepreneurs in these techniques have caught the imagination of the public media and many of the techniques such as laser angioplasty have been widely publicised with the result that some patients demand an interventional procedure when a more conventional procedure is indicated. These procedures require significant ability with three dimensional imaging and with the devices used to perform the techniques. As a result the complication rates are mostly directly related to the experience of the person performing them. One factor, independent of the operator, which has caused reduction of complication rates, has been the introduction of nonionic iodinated radiographic contrast media. The nonionic compounds have a lower osmolality than conven-
tional ionic contrast media and are about five times less likely to cause minor and major contrast media reactions.’
ANGIOPLASTY In spite of the advances in angioplasty and devices in the past few years there is still a considerable place for conventional arterial surgery as only about 30% of lower limb arterial lesions are suitable for angioplasty . If a localised and symptomatic arterial lesion is found in the distal aorta or lower limbs then balloon angioplasty is indicated as a first choice. A prospective analysis of 984 consecutive lesions by Johnston er al. showed an initial success rate of 89% and a five year patency rate of 48%.’ Four variables were found to be significant predictors of success. These were the indication for the angioplasty (claudication vs salvage), the site of the angioplasty (common iliac vs other), severity of the lesion (stenosis vs occlusion) and peripheral run-off (good vs poor). Almost all lesions in the lower limbs suitable for angioplasty are readily detected with a careful clinical examination. Surgical back-up of all angioplasties is essential as occasionally complications may arise which may require surgical intervention. Some surgeons advocate performance of angioplasty only in an operating theatre setting, but in the Royal Melbourne Hospital’s experience of over 2000 peripheral angioplasties this is not warranted in terms of patient care or of cost. The type of treatment required can only be determined after angiography (Figure 1). The major problem of balloon angioplasty is recurrence of stenosis. This occurs in about 25-30% of angioplasties’ and has stimulated the development of alternative or adjunctive measures. The most widely known of these is the thermal Nd-YAG laser. The laser energy is used to heat a metal tip on the laser fibre to 500 degrees C and the hot tip burns a hole through
Reprint requests to: Dr K. Thomson, Consulant Radiologist, Department of Radiology, The Royal Melbourne Hospital P.O., Parkville, VIC. 3050, Australia.
902
Aust NZ J Med 1991; 21
THOMSON
f?1 Puncture Site Dbs Vascular ObSeIval~OnS
Clin~cal Follawup -readmill Testing E x e m s 8 program Slop Smoking Anliplatelet Drugs
1
Fipre 1: A flowchart of suggested actions prior to angioplasty of the lower limbs.
the atheroma. The thermal laser requires a subsequent balloon angioplasty but it is claimed that much higher long term patency rates are produced by the laser and longer occluded segments can be treated su~cessfully.~ Overseas controversy rages about the place of laser a n g i ~ p l a s t yThis . ~ is in part due to the lack of prospective controlled trials and the rapid advances in balloon and wire guide technology over the past few years. A major Australian trial of laser angioplasty is now underway in New South Wales to investigate long term patency for laser assisted angioplasty and the initial report of an American prospective trial showed that initial success was independent of whether the laser or a wire guide was used.6 The Excimer laser operates at a lower wavelength and produces a photoablative effect instead of charring by heat. In theory the Excimer ablates the atheroma producing a clean cut with less thermal damage to the normal arterial wall. Clinical trials of the Excimer are only just beginning. Other wavelengths of light are under investigation but it is likely that, unless there are major developments in laser technology, the use of lasers for treatment of atheroma will be limited to photoablative recanalisation of short occluded segments which cannot be opened by other percutaneous means. Atherectomy devices which remove the atheroma directly are claimed to have longer patency rates and INTERVENTIONAL RADIOLOGY - A REVIEW
Figure 2: TEC atherectomy of the tibia1 arteries performed for continuing claudication some months after a femoropopliteal vein bypass (arrow). (a) The anterior tibial artery is stenosed and the posterior tibial trunk is occluded. (b) Restoration of a good lumen in both vessels after the TEC catheter has been passed. Foot pulses were normal after this procedure.
lower embolic complications than balloon angioplasty alone (Figure 2(a), (2b)). Initial results show similar complications and restenosis to balloon angioplasty.' Transluminal angioplasty for renal artery stenosis offers the hope that antihypertensive medication can be reduced or ceased and that any progression of atherosclerosis as a result of the hypertension will be halted. Results in atherosclerotic disease arc poor when 903 Aust NZ J Med 1991; 21
Figure 4: Palmaz articulated stent 6 months after placement. The abdominal aorta and both renal arteries have been opened along their posterior aspects. (The patient died of coronary artery disease). The aortic ends of the stents were intentionally placed to project slightly into the aorta. The neointimal lining of the stents is quite smooth and free of thrombus and the steel mesh is almost completely covered except at the aortic end.
Figure 3: Palmaz Stent in abdominal aortic stenosis. (a) A
high grade stenosis of the abdominal aorta in a young obese woman. A previous attempt at surgical bypass had failed. (6) Angiographic result after balloon angioplasty and insertion of a Palmaz s e n t dilated to a diameter of 10 mm. She has been asymptomatic for the past year. Note the extensive atherosclerosis in the renal arteries.
accidents within one year of treatment. Careful clinical follow-up and treatment for atherosclerosis is required in these patients even when the renal angioplasty has been radiologically 'successful'. Treatment of acute coronary thrombosis by direct arterial infusion has been largely replaced by intravenous therapy for reasons of cost and practicality but in the lower limbs there is still a place for this method of treatment as intrathrombus injections of thrombolytics may recanalise even chronic occlusions. Almost always there is an underlying lesion which requires further treatment by balloon or another method. If the viability of the leg is precarious, then there may not be sufficient time for thrombolysis and urgent embolectomy is indicated. Lammer et aL'O reported 81% cumulative patency at two years after thrombolysis and angioplasty in 107 long (mean length 12.5 cm) occluded arterial segments. Should the balloon dilatation fail to establish a satisfactory lumen then an endovascular stent may be inserted percutaneously to resist the elastic recoil of the arterial wall and hold back dissection flaps and loose fragments of atheroma against the wall." The stents are of two types; balloon-expandable or selfexpanding. Either type may be rigid or flexible. Comparison of each type has not been made. Experience in 30 iliac stent placements at the Royal Melbourne Hospital with up to 18 months' follow-up has shown only one restenosis (not at the site of the stent) and two cases of peripheral embolisation. The stent offers increased patency in angioplasty of occluded segments" and also in the aorta where elastic recoil is more likely after angioplasty (Figure 3).
compared with results in other types of stenoses.8 Using the same criteria as would be applied to a new antihypertensive drug a review of 23 cases by Grimm et aL9 showed only two of six patients with fibromuscular disease were considered cured. Of the three patients with atherosclerotic stenoses who were considered improved all developed cerebrovascular 904 Aust NZ J Med 1991; 2 1
THOMSON
The availability of stents has also made renal angioplasty more widely available as restenosis of lesions at the renal artery orifice within six months after balloon dilatation has been reported to be between 80% and 100%.'* Stents appear ideal as a means to overcome this problem but it remains to be seen if the intimal covering which forms on all stents will reduce the renal artery lumen significantly or not (Figure 4). A worldwide multicentre trial of balloon-expandable renal artery stents is currently underway. The complications of peripheral angioplasty are listed in the angioplasty flowchart. About 2% of patients will require surgery after a balloon angioplasty. The most common reasons for surgery are peripheral embolism and acute occlusion of the dilated arterial segment. The worst complication is to advance a patient from simple claudication to rest pain or limb salvage as a result of a failed angioplasty. Multiple small emboli cause the syndrome of 'trash foot' which may result in amputation for unremitting ischaemia. Coronary artery angioplasty suffers from the same restenosis problems as angioplasty elsewhere. Lasers, atherectomy devices and stents are also being investigated in the coronary circulation. Coronary angioplasty has been increasing far faster than lower limb angioplasty and the indications for coronary angioplasty depend somewhat on the aggression and expertise of the cardiologist concerned. For multivessel angioplasty, a clinical success rate of 95%, with emergency surgery in 2.870, myocardial infarction in 3.0% and hospital death rate of 0.4% has been reported.I3 Similar or better results should be expected for simpler lesions. Suitable lesions for coronary angioplasty are: 0 Proximal severe (>70%) stenosis of one vessel; 0 recent occlusion of a single vessel; 0 severe (>70%) stenosis of two major vessels; 0 symptomatic restenosis of prior angioplasty; 0 residual stenosis post thrombolytic therapy; 0 coronary graft stenosis; 0 single vessel occlusion during myocardial infarction; multiple discrete stenoses in a single vessel. Lesions which have a high risk or a low chance of success are: 0 Left main stem stenoses or equivalent; 0 chronic occlusions (? try laser); 0 multiple stenoses in multiple vessels with a large amount of myocardium at risk. The problems of dissection and perforation are more serious in the coronary circulation and the expertise required for good results is only maintained with a large continuing experience. Early results listed by the National Heart, Lung and Blood Institute PTCA RegistryI4 indicated a complication rate overall of 2 1.1% with coronary dissection, occlusion or INTERVENTIONAL RADIOLOGY
- A REVIEW
myocardial infarction in 10% of the patients and death in 0.9%.Current results are much better than this and our own expectation is an infarction rate of less than 5%. A cardiac bypass team on standby and a counter pulsation aortic balloon pump are necessary for effective and safe management of complications. Aortic valvuloplasty is used for high risk patients who are generally old, frail and unfit for aortic replacement surgery. This procedure is still being evaluated. Letac el ~ 1 . 'reported ~ that in 144 patients who had aortic valvuloplasty, there were 24 deaths in the followup period (mean eight months) but that 84% of the survivors had good clinical improvement. Most of the deaths were due to existing cardiac disease. The aim of aortic valvuloplasty should be to increase the aortic valve area as much as possible rather than to just reduce the peak to peak aortic valve gradient. Pulmonary valvuloplasty for congenital stenosis is a useful procedure and has a high success rate.I6 In a series of 75 patients including three neonates with critical pulmonary valve stenosis, the mean pulmonary valve gradient was reduced significantly after angioplasty with lasting clinical and objective improvement.
ARTERIAL EMBOLOTHERAPY Control of haemorrhage is the most common indication for transcatheter occlusion. New catheter technology and occlusion devices have made this procedure easier." Superselective embolism is used for pelvic or abdominal bleeding after trauma, for uncontrolled bleeding from the nose and for bleeding resulting from operative procedures or biopsy of deep organs. Because the embolism is superselective, tissue damage from the occlusion is minimised. The type of material injected depends on the catheter size and the desired effect. For example a detachable balloon is the only device which can be tried in a number of positions before permanent occlusion, and for complete capillary occlusion a liquid agent is desirable. Some of the materials commonly used are: 0 Collagen paste; gelfoam or collagen pieces; wireguide and dacron coils; detachable balloons; 0 liquid occluders (silicones, glues, irritants). Angiography is useful in localising gastrointestinal bleeding if the patient is bleeding at the time of the angiogram at a rate of 0.5 mLlminute or more." Often the bleeding has stopped at the time a patient produces a malena stool. Low rate or intermittent bleeding is best localised by nuclear medicine techniques using labelled red cells (Figure 5). Control of gastrointestinal bleeding by vessel occlusion is generally recommended only in the stomach and first part of the d u ~ d e n u m . ' ~ The multiple arteries supplying the stomach protect Aust NZ J Med 1991; 21
905
1
Gastro-Intestinal Bleeding
I
Blood replacement
. Nudebr Medklno Scan
Anniogrsphy
BIwdInQ Sne Found
Superseleotive Embolisation
Pitressin Infusion
Eleclive C0rrl)ctive
Emergency
Figure 5: A flowchart for the management of gastrointestinal bleeding by interventional radiology.
it from ischaemia. In the remainder of the bowel, embolisation of an artery may cause necrosis or late stenosis of the ischaemic segment. Sebrechts and BooksteinZopresented a series of 28 patients who had embolotherapy for lower gastrointestinal haemorrhage. They Controlled the bleeding in 26 patients (93%)and found mucosal or transmural infarction in only three patients at the time of bowel resection one to four days later. In the remainder of the bowel, control of haemorrhage can be achieved by ultra-low dose (
