SEARCH · PubMed Health

Results for “Collateral Circulation”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,711 records · Page 95Linked to original sources

PubMed1993

Splenic infarction after splenorenal arterial bypass.

Because of the spleen's extensive collateral circulation, the risk of splenic infarction after splenorenal arterial bypass (SRB) has been considered negligible. We report four patients in whom splenic infarctions developed after SRB. Splenic infarction developed in one patient at the time of SRB, and symptoms of splenic abscess (fever, abdominal pain, and leukocytosis) that proved to be splenic infarctions at laparotomy developed in three patients 2 to 16 days after the operation. Factors possibly contributing to splenic infarction could be determined for three patients. These included interruption of collateral vessels, intraoperative hypotension and disseminated intravascular coagulation, and distal splenic artery ligation. Normal Doppler flow was detected in the splenic parenchyma during test occlusions of the splenic artery before SRB in three patients. Our experience suggests that existing collateral circulation may not always sustain splenic viability after SRB, and some patients may not be suitable candidates for this operation. Factors such as adequacy of inflow, splenic artery length, and risk of perioperative hypotension should be considered.

Aged↗

PubMedDate not supplied

[Renovascular hypertension in a child with type 1 neurofibromatosis].

Arterial hypertension in pediatric patients with neurofibromatosis type 1 (NF 1) is usually due to renal artery stenosis (RAS) mainly involving the proximal part of the vessel. The treatment modalities are highly individualized. In severe and/or bilateral RAS, antihypertensive drugs are either ineffective or have the potential risk for acute renal failure, while percutaneous transluminal angioplasty (PTA) has limited success due to the ostial localization of RAS and the tough fibrotic tissue involved that is refractory to dilatation Renal autotransplantation has potential advantages when medical control and PTA/or bypass techniques failed. Here we report 5 year-old girl with NF 1 and hyponatremic hypertensive syndrome due to severe bilateral disease, occluded proximal part of the right artery and ostial stenosis (80%) of the left one. Only left kidney was identified on 99 m Tc DTPA, but the right one was visualized on the renal ultrasonography and in the late phase of arterial renography due to well developed collateral circulation. Multiple antihypertensive drugs (nifedipine, labetolol and minoxidil) in maximal doses and PTA failed to normalize BP while short term therapy with ACEI with NF1 and hyponatremic hypertensive syndrome due to severe bilateral renovascular disease; occluded proximal part of the right renal artery and ostial stenosis (80%) of the left one. Only left kidney was identified on 99 m Tc DTPA, but the right one was visualized on the renal ultrasonography and in the late phase of arterial renography due to well developed collateral circulation. Multiple antiphypertensive drugs (nifedipine, labetolol and minoxidil) in maximal doses and PTA failed to normalize BP while. short term therapy with ACEI, captopril induced transient acute renal failure. Autotransplantation of right kidney saved its function and improved BP control. Our current case Autotransplantation of right kidney saved its function and improved BP control. Our current case is illustrative for a difficult management of renovascular hypertension in children with NF1. This is the first and up to now the only case of autotransplantation performed in Yugoslavia.

Child, Preschool↗

PubMed1981

Embolization of segments of the circle of Willis and adjacent branches for management of certain inoperable cerebral arteriovenous malformations.

Most large cerebral arteriovenous malformations (AVM's) in the territories of the penetrating arteries arising from the circle of Willis, including the proximal anterior, middle, and posterior cerebral arteries, have been considered untreatable. However, the pattern of collateral circulation which accompanies these lesions presents the possibility of completely occluding certain segments of the circle of Willis and adjacent major branches without producing infarction distally in the cerebral hemisphere or in the critical areas occupied by the AVM itself. The ensuing reduction of arterial pressure within the AVM may reduce the likelihood of hemorrhage or progressive enlargement. Four patients in whom this was accomplished in whole or in part by embolization are described. In one patient, infarction did ensure but the potential for collateral circulation had been restricted by the passage of emboli into the pericallosal artery. In the others, angiographic filling of the lesion was considerably reduced without worsening of their neurological deficits. One patient had recovery of neurological loss following the procedure, and another was slightly improved. Over follow-up periods of up to 28 months there have been no recurrent hemorrhages or further progression of neurological deficits. However, final assessment of the efficacy of this procedure will require longer follow-up intervals and additional patients.

Adolescent↗

PubMed1996

Posterior hip dislocations: a cadaveric angiographic study.

Avascular necrosis (AVN) of the femoral head after a traumatic posterior hip dislocation (Thompson and Epstein type I) has been hypothesized to occur due to changes in blood flow. However, to the best of our knowledge of the English literature, a human cadaveric angiographic study has never been performed to delineate these vascular changes. Six fresh frozen human cadavers were used to examine the effects of posterior hip dislocation on the extraosseous and intraosseous blood supply to the femoral head and neck. After a forceful posterior hip dislocation was performed on the cadavers, the proximal vessels were injected with a radioopaque colored latex liquid polymer (Microfil) and examined under cinefluoroscopy. The contra lateral hips were used as controls and were examined in a similar manner. Both hips of the cadavers were harvested, and a macroscopic and microscopic examination was performed. The cine-fluoroscopic examination delineated the dynamic effects of posterior dislocation on the surrounding vasculature. Filling defects were most notable at the junction of the external iliac and common femoral arteries. Filling defects were also present in the circumflex vessels. Compared to controls, the common femoral and circumflex vessel filling defects were statistically significant (p < 0.004). These defects were secondary to an apparent stretching and twisting of the artery caused by the pull and rotation of the dislocated hip. A number of collateral vessels from the gluteal arteries were also demonstrated on fluoroscopic examination. The macro and microscopic examination did not show a qualitative or a quantitative difference in the amount of latex present in the dislocated and control groups. Based on the results of this study, changes in the extraosseous blood flow to the dislocated hip do occur. The vessels that appear to be most affected by the dislocation are the common femoral and circumflex vessels. However, these extraosseous changes do not consistently result in changes in the intraosseous blood flow possibly due to collateral circulation. Relocating the femoral head in a traumatic posterior hip dislocation may provide earlier blood flow to the femoral head by relieving tension across the femoral and circumflex vessels. Delayed relocation could contribute to the development of AVN in the femoral head by not only inducing immediate ischemia at the time of injury but by also producing a progressive and delayed form of arterial damage in the femoral and circumflex vessels. AVN may not be an absolute outcome of posterior hip dislocations due to preexisting collateral circulation and/or the preservation of the femoral circumflex vessels.

Aged↗

PubMed2006

Surgical removal of jugular paragangliomas after stenting of the intratemporal internal carotid artery: a preliminary report.

OBJECTIVE: Jugular paragangliomas with extensive involvement of the internal carotid artery (ICA) represent a true challenge for surgeons, especially in the presence of inadequate collateral circulation through the circle of Willis. The aim of our study is to present a preliminary report of our experience with the surgical removal of three such cases using the stenting of the ICA as the method of choice for protecting and preserving the integrity of the artery. METHODS: This retrospective study was conducted at Gruppo Otologico, a private referral center for neurotology and skull base surgery. The subjects of our study are three cases of jugular paragangliomas with extensive involvement of the ICA and inadequate collateral circulation. These cases are the first three cases operated at our center after stenting of the intratemporal portion of the ICA. RESULTS: Complete surgical removal of the tumor, including the part involving the ICA, was achieved in all cases. Over a follow-up period of 22 to 30 months, no complications occurred and the patency of the stented arteries was preserved. CONCLUSION: Although more follow-up is still needed before establishing the exact long-term outcome of stenting the intratemporal ICA, our preliminary report shows that the stent has facilitated the complete surgical removal of the tumor, preserving the integrity of the ICA.

Adult↗

PubMed1989

Complete occlusion of the left main coronary artery: clinical and angiographic observations in five cases.

Involvement of the left main coronary artery is observed in approximately 5 to 8% of patients with coronary artery lesions detected by coronary angiography, but occlusion of the left main artery is a very infrequent finding. Out of approximately 4000 patients undergoing coronary angiography, four men and one woman, 37 to 60 years old, showed total occlusion of this vessel. Four of them had angina pectoris and three had had a myocardial infarction. All five showed deep ST depression in V 2(or 3)-6 during bicycle exercise testing. Apart from the left main artery occlusion, all had significant obstructive lesions in other coronary vessels, including the right coronary artery or its major branches. There was collateral circulation from the right coronary artery in all patients. Left ventricular function was well preserved in three patients and markedly impaired in two. Four patients underwent bypass surgery and they have been followed for 10 to 28 months. Three are free of angina and one has only minimal angina. One patient refused surgery and he continued to have severe angina despite intense medical treatment. He died suddenly after 30 months follow-up. In patients with complete occlusion of the left main coronary artery, development of adequate collateral flow seems important in preserving left ventricular function, but collaterals are usually insufficient to prevent angina. Moreover, associated obstructive lesions in other coronary arteries constitute a potential threat to the collateral circulation. Effective symptomatic relief is obtained by coronary bypass grafting, and revascularization may also improve prognosis in this subset of patients with coronary heart disease.

Adult↗

PubMedDate not supplied

Physiologic and clinical significance of myocardial blood flow quantitation: what is expected from these measurements in the clinical ward and in the physiology laboratory?

In this essay we review data on absolute quantitation of myocardial blood flow (MBF) in humans. Earlier work established that coronary heart disease (CAD) can be detected by coronary angiography and that this disease has characteristic features at rest and during stress, which indicate the linkage between regional metabolic needs and myocardial perfusion. In the 1970s myocardial perfusion was mapped in patients with radioxenon, but this method had significant technical limitations. About the same time, radioactive microspheres were introduced for cardiovascular research and investigations; these particles provided insights on MBF in acute infarction and ischemia, myocardial reperfusion, collateral circulation, myocardial blood flow during exercise, coronary flow reserve (CFR), and layer-to-layer distribution of MBF. Studies with microspheres also permitted investigators to establish the presence in the heart of MBF heterogeneity. Currently, there are several techniques that aim at extending these concepts into clinical investigation. Two of these techniques, i.e. Doppler coronary flow velocity and fast magnetic resonance imaging assess epicardial flow dynamics and CFR. Contrast myocardial echocardiography is another novel technique which has been useful in mapping the area at risk, reperfusion, myocardial viability and collateral circulation. This essay also considers the emerging technique of intracoronary ultrasound which has shown evidence of disease underestimation by conventional contrast angiography. Positron emission tomography (PET) is a noninvasive technique that uniquely and quantitatively maps myocardial perfusion and CFR. The latter can be computed before and after angioplasty. PET studies have further demonstrated that chronic myocardial ischemia does not exist as a distinct state in patients with CAD. From the above investigations the concept has arisen that not only is CAD an entity involving epicardial vessels but also, in a significant portion of patients, an abnormal microcirculation plays an important role in the pathogenesis of ischemic syndromes. PET studies have relatively low spatial resolution since they cannot resolve layer-to-layer absolute MBF.

Animals↗

PubMed1999

Stroke: indications for emergent surgical intervention.

As the brain attack message is disseminated throughout our medical community and the awareness of the public increases, neurosurgeons will have the opportunity to treat patients with stroke at a much earlier time in the evolution of the process than we have been accustomed. Are the relatively unimpressive results of acute surgical intervention in patients operated on later in the course of the disease applicable to those who seek medical attention early, within the first few hours of ictus? There is little firm data. However, there is an overwhelming amount of anecdotal and experimental evidence supporting the potential for ultra-early intervention, which frequently should be surgical. New surgical techniques may improve safety and feasibility of emergent operations. In the coming years, diagnostic techniques such as perfusion/diffusion magnetic resonance imaging will allow the clinician to determine who may benefit from intervention. These determinations will be made on physiological data, addressing the issues of tissue viability and degree of compromise of the blood-brain barrier. In the future, the window of opportunity for intervention will not be solely a function of time from ictus or a qualitative impression based on collateral circulation as extrapolated from angiography, transcranial Doppler, or magnetic resonance angiography. These new magnetic resonance imaging techniques, which are beginning to be tested clinically or are still in the developmental stages, will provide the functional data now provided by positron emission tomography and xenon computed tomography, but with improved sensitivity, specificity, and logistical ease. Neurosurgeons have been leaders in stroke care and have provided some of the most important experimental rationale for the brain attack concept. These contributions include demonstration of the ischemic penumbra, the importance of time and potential collateral circulation as factors determining viability of ischemic tissue, and the value of early revascularization and many neuroprotective maneuvers in preserving brain tissue after arterial occlusion. There is every reason to preserve and to enhance the role of the neurosurgeon as a "stroke expert" and as a leading member of the brain attack team. Early access to patients with stroke will offer us the opportunity to test clinically, in a rigorous fashion, the value of surgical revascularization procedures (open or endovascular) and medical maneuvers that we have developed clinically and tested in the laboratory. We have shown, as we did with the bypass study, that neurosurgeons know how to perform these trials and abide by their results, even when they are not to our liking.

Cerebral Angiography↗

PubMed1991

Hypertension and hyperglycemia in experimental stroke.

Both diabetes mellitus and hypertension are risk factors for stroke and also influence prognosis following stroke. Experimentally, hyperglycemia augments cortical infarct size in stroke models where collateral circulation exists, and infarct size in hypertensive rats is larger than in normotensive strains. Whether the deleterious effect of hyperglycemia is altered in the setting of hypertension has not previously been studied experimentally. The effect of hyperglycemia on infarct size in spontaneously hypertensive rats was examined in this study. Focal neocortical cerebral ischemia was induced by tandem right common carotid and middle cerebral artery occlusion. Preischemic hyperglycemia had no influence on infarct volume whether the duration of postischemic hyperglycemia was transient or prolonged. Although hyperglycemia increases infarct size in cortical stroke models where collateral circulation is available, this study demonstrates the effect can be modified by the presence of underlying hypertension.

Animals↗

PubMedDate not supplied

Clinical features, image analysis, and laparoscopic and histological liver findings in Budd-Chiari syndrome.

BACKGROUND/AIMS: Clinical manifestations and histological features of the liver in Budd-Chiari syndrome (BCS), with or without idiopathic membranous obstruction of the inferior vena cava (MOVC), vary according to whether BCS is acute, subacute or chronic. We clarified the diagnostic features in 6 patients with MOVC and in 1 without MOVC. METHODOLOGY: Five patients with subacute or chronic type BCS with MOVC complaining of epigastric pain, hematemesis and encephalopathy, and signs of portal hypertension or collateral circulation were seen. There was 1 asymptomatic patient with MOVC. One patient with acute type BCS without MOVC revealed hepatic and multi-organ failure. Liver function tests in BCS with MOVC were similar to those in liver cirrhosis, and laboratory data in acute type without MOVC were quite the same as those seen in fulminant hepatitis. Non-invasive image analysis by US, CT and MRI showed thrombi and obstruction of the IVC, and extrahepatic vasculature or communication between hepatic veins and IVC. Vena cavography showed the length of obstruction in IVC and collateral circulation in the extrahepatic or intrahepatic veins. Liver biopsy demonstrated massive hemorrhagic necrosis in acute type without MOVC, and laparoscopy with liver biopsy in asymptomatic, subacute and chronic type with MOVC showed subcapsular hemorrhage, congestion, fibrosis, and cirrhotic features. CONCLUSIONS: The non-invasive image analysis was complementary to vena cavography, and liver biopsy with or without laparoscopy was essential not only for diagnosis of acute, subacute, and chronic BCS, but also for therapeutic decision-making.

Adult↗

PubMed2001

Total knee arthroplasty in a patient with chronic occlusion of the superficial femoral artery.

In a 67-year-old patient with severe valgus gonarthrosis and chronic occlusion of the superficial femoral artery on the same side, total knee replacement was performed without preceding angioplasty because the collateral circulation was intact. No tourniquet was used. To leave the peripatellar arterial ring intact on one side in this case of lateral patellar maltracking, a lateral approach was used. In this approach, a lateral release forms part of the approach itself. To achieve gentle eversion of the patella, the tibial tubercle was osteotomized. One year postoperatively, the patient was satisfied with the outcome and showed no clinical signs of any vascular deterioration. It is concluded that total knee replacement may be possible in the presence of chronic occlusion of the superficial femoral artery provided that the collateral circulation is intact.

Aged↗

PubMed2000

Effects of preinfarction angina on myocardial injury in patients with acute myocardial infarction: a study with resting 123I-BMIPP and 201T1 myocardial SPECT.

METHODS: Recent studies have suggested that patients with preinfarction angina have smaller infarcts and a better in-hospital outcome than those without angina. The mechanisms responsible for limitation of infarct size in the presence of preinfarction angina are unclear. We examined the effects of preinfarction angina on myocardial injury in patients with the first acute myocardial infarction with resting 123I-15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) 201TI myocardial scanning performed within 1 mo of infarction. RESULTS: Of 136 patients tested, 48 (35%) had preinfarction angina within 72 h before infarction, whereas 88 (65%) did not. BMIPP and 201TI defects were scored in 9 segments of the left ventricle (0 = normal, 1 = mild defect, 2 = moderate defect, 3 = severe defect, and 4 = no uptake). The total defect score was defined as the sum of the defect scores. There was no significant difference in percentage diameters of stenoses of infarct-related arteries, collateral circulation, total defect scores for BMIPP, or 201TI between the groups with and without preinfarction angina. However, the ratio of total defect score for 201TI to that for BMIPP was significantly smaller for patients with than for those without preinfarction angina (0.64 +/- 0.21 versus 0.74 +/- 0.25, respectively; P = 0.007). CONCLUSION: Preinfarction angina did not affect the areas at risk in acute myocardial infarction, as shown by BMIPP defect, but decreased necrotic myocardium in the areas at risk, as shown by 201TI defect, and increased metabolically damaged but viable myocardium, as shown by BMIPP and 201TI mismatch through unidentified mechanisms other than collateral circulation (e.g., ischemic preconditioning).

Angina, Unstable↗

PubMed1999

Long saphenous-vein grafts for extracranial and intracranial internal carotid aneurysms amenable neither to clipping nor to endovascular treatment.

BACKGROUND: In the treatment of patients with unclippable, uncoilable internal carotid artery aneurysms it may be necessary to use high-flow bypass grafts. The indications, surgical techniques and complications are discussed. METHODS: During a 12- year period, 20 saphenous vein grafts were performed in 20 patients. The 20 aneurysms were located in the prepetrous or intrapetrous internal carotid artery in 7 cases, the intracavernous in 9 and intracranial internal carotid artery in 4. All aneurysms were symptomatic. The vein graft was interposed between the internal carotid artery at the neck and the intrapetrous carotid, from the internal carotid artery at the neck to a branch of the middle cerebral artery, or from the external carotid artery and a branch of the middle cerebral artery, according to the collateral circulation assessed with a 30-minute the balloon test occlusion during electroencephalographic recording. RESULTS: Only one of the 20 grafts occluded. One patient died from a large postoperative cerebral infarction. One patient had cerebral ischemia with transient hemiparesis; and three patients had mixed aphasia that resolved completely within two weeks. Radiological follow-up monitoring was by magnetic resonance imaging, magnetic resonance angiography or digital angiography. Postoperative follow-up ranged from 1 to 12 years (mean 3.7 years). CONCLUSIONS: Our experience in this series suggests that the indications for cerebral revascularization should be widened, even to include patients with adequate collateral circulation, particularly those who have a long life expectancy.

Adult↗

PubMed1989

Use of the omentum in chest-wall reconstruction.

Increased use of the omentum in chest-wall reconstruction has paralleled the refinement of anatomic knowledge and the development of safe mobilization techniques. Important anatomic points are the omental attachments to surrounding structures, the major blood supply from the left and right gastroepiploic vessels, and the collateral circulation via the gastroepiploic arch and Barkow's marginal artery. Mobilization of the omentum to the thorax involves division of its attachments to the transverse colon and separation from the greater curvature to fabricate a bipedicled flap. Most anterior chest wounds and virtually all mediastinal wounds can be covered with the omentum based on both sets of gastroepiploic vessels. The arc of transposition is increased when the omentum is based on a single pedicle, allowing coverage of virtually all chest-wall defects. The final method of increasing flap length involves division of the gastroepiploic arch and reliance on Barkow's marginal artery as collateral circulation to maintain flap viability. With regard to chest-wall reconstruction, we have included the omentum in the armamentarium of flaps used to cover mediastinal wounds. The omentum is our flap of choice for the reconstruction of most radiation injuries of the chest wall. The omentum may also be used to provide protection to visceral anastomoses, vascular conduits, and damaged structures in the chest, as well as to cover defects secondary to tumor excision or trauma. In brief, the omentum has proved to be a most dependable and versatile flap, particularly applicable to chest-wall reconstruction.

Humans↗

PubMed2006

The superior vena cava syndrome caused by malignant disease. Imaging with multi-detector row CT.

OBJECTIVE: The superior vena cava (SVC) obstruction by malignant diseases is either by direct invasion and compression or by tumour thrombus of the SVC. Whatever is its cause, obstruction of the SVC causes elevated pressure in the veins draining into the SVC and increased or reversed blood flow through collateral vessels. Severity of the syndrome depends on the collateral vascular system development. Therefore, imaging of the collateral veins with variable location and connection is important in determining the extension and management of the disease. Our aims are to describe collateral vessels of the superior vena cava syndrome (SVCS) related with the malignant diseases and to assess the ability of multi-detector row CT with multiplanar and 3D volume rendering techniques in determining and describing collateral circulations. MATERIALS AND METHODS: We present CT angiography findings of seven patients with small cell carcinoma of the lung (n = 2), squamous cell carcinoma of the lung (n = 3), Hodgkin disease of the thorax (n = 1), and squamous cell carcinoma of the oesophagus (n = 1). The patients received contrast-enhanced CT scans of the chest and abdomen on a multi-detector row CT during breath holding at suspended inspiration. RESULTS: CT images revealed the cause and level of the SVC obstruction in all patients with axial and multiplanar reconstructed images. The SVC showed total obstruction in five patients and partial obstruction in two patients. The most common experienced collateral vessels were azygos vein (6), intercostal veins (6), mediastinal veins (6), paravertebral veins (5), hemiazygos vein (5), thoracoepigastric vein (5), internal mammary vein (5), thoracoacromioclavicular venous plexus (5), and anterior chest wall veins (5). While one case showed the portal-systemic shunt, V. cordis media and sinus coronarius with phrenic veins were enlarged in two cases, and the left adrenal vein was enlarged in a patient. In one case, the azygos vein with reversed blood flow was drained into both inferior vena cava and hemiazygos vein with the left renal vein. CONCLUSION: Multi-detector row CT with multiplanar and 3D imaging is an effective tool in evaluation of the SVCS and has a greater advantage than the other imaging techniques. 3D volume rendering is a useful technique in determining and describing collateral circulations in addition to the primary disease process.

Adult↗

PubMed1980

Reflections on the etiology of hot spots on liver scans.

Liver scintigraphy demonstrated areas of increased radiocolloid uptake in three cases with obstruction of the superior vena cava and extensive collateral circulation through the veins of the thoracic wall. The pattern of the hyperactive zones is indicative of predominant vascularization of the liver via the umbilical vein, with high colloid particle deposition in the quadrate lobe and adjacent part of the right lobe. These liver regions vascularized by the first intrahepatic branches of the umbilical vein as demonstrated by postmortem angiography, probably extract a great portion of the tracer dose, resulting in localized hyperactivity. An identical liver scan image was, however, found in a fourth case without evident superior vena cava syndrome. In this patient, presenting with a bronchus carcinoma with paratracheal metastatic lymph nodes, there is no explanation metastatic lymph nodes, there is no explanation (collateral circulation without vena cava obstruction?) for the abnormal tracer distribution within the liver.

Adult↗

PubMedDate not supplied

[Duality of angiotensin II receptors and risk for stroke and cancer: what is the connection?].

Angiotensin II (AII) acts by 2 types of receptors: the ATI receptor which mediates its actions on vasoconstriction, renin (inhibition) and aldosterone (stimulation) secretions, cellular proliferation and angiogenesis and the non-AT1 (often called AT2) receptors. Mainly expressed in the embryon these latter may favor cellular differentiation and recruitment of collateral circulation. Angiotensin converting enzyme inhibitors (ACEI) decrease the synthesis of All and therefore the stimulation of both receptor types whereas AT1-receptor antagonists (AT1RA) block only the stimulation of these latter and increase the stimulation of AT2 receptor since they increase the production of All secondarily to the inhibition of the feedback of renin secretion by All. Experimentally ACEI and AT1RA decrease angiogenesis and cellular proliferation and favor cellular differentiation which could explain the protective effect of ACEI against cancer suggested recently in a Scotish study. Despite of their common suppressive effect on angiogenesis AT1RA may better than ACEI protect against ischemic events specially the cerebral ones because they favor the rapid recruitment of collateral circulation. This has been demonstrated for losartan in case of abrupt ligation of the carotid in the gerbil since its previous administration protects against fatal cerebral ischemia whereas its previous administration with enalapril abolishes this protection. These data may explain why, in the CAPP trial, captopril which has prevented more effectively diabetes occurrence could not be proved superior to diuretics and/or betablocker in the prevention of myocardial infarction and specially of strokes for which exist on the contrary a suspicion of a lower protection. Therefore a comparative trial between AT1RA and ACEI in the prevention of stroke recurrence should appear as a priority for Public Health and Pharmaceutical Industry Authorities.

Angiotensin II↗

PubMed1987

Limitation of coronary thrombolysis: experimental study of reperfusion after ischemia.

Contraction band necrosis (CBN), coagulation necrosis (CN) and infarct size, expressed as CBN + CN, were quantitatively analyzed in 15 pig hearts without collateral circulation. The left anterior descending coronary artery was ligated for 60 and 120 minutes and then reperfused for eight hours (group 1 and 2, respectively). Five hearts were not reperfused (group 3). There was no change in hemodynamics with either occlusion or reperfusion. Regional myocardial blood flow, measured by the generated hydrogen gas clearance method, decreased to almost zero after occlusion but recovered during reperfusion. Percent infarct area of the perfused area in group 1, 2 and 3 were 80 +/- 9, 96 +/- 2% and 95 +/- 3%, respectively. The percent area of CBN was 68 +/- 11% in group 1, 2 +/- 1% in group 2 and 2 +/- 2% in group 3. We conclude that in pig hearts without collateral circulation, the transmural infarct, two-thirds of which is occupied by CBN, is evident even in reperfusion following one-hour occlusion. Therefore, in patients with acute myocardial infarction, coronary thrombolysis should be performed within one hour after the onset of the infarction to reduce the infarct size.

Animals↗