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PubMed1979

[Theoretical viewpoints of coronary hemodynamics relative to the localization of arterial stenoses and the collateral function with special reference to the so-called steal effect].

1. On a simple branched model of the vascular system is deduced that the restriction of the reserve of blood supply (coronary reserve) occurring in arterial constrictions depends not only on the degree of constrictions, but also on their type of distribution, by means of which peculiarities of the univascular diseases in contrast to the multivascular diseases are the result. 2. Constrictions further the formation of the collateral circulation, the size of which in the same initial pressure increases with the degree of constriction and the decrease of the peripheral resistance. 3. The effects of the collateral circulation are fully different for proximally and distally localized stenoses. Proximal stenoses lead the collateral circulation in direction to the narrowed area, peripheral narrowings of the circulation, however, to the counter-direction. 4. A Steal effect is possible only in peripheral narrowings of the circulation. Its haemodynamic conditions are described in detail. 5. As haemodynamic explanation for the positive dipyridamol test the hypothesis arises that it might refer to remarkable peripheral constrictions. 6. The application of vasodilators is from the haemodynamic point of view indicated above all in proximal constrictions, when distally from this there are interarterial anastomoses. Repression is necessary in peripheral narrowings, when their reserve of blood supply is already consumed by vasodilatation. In these cases is to be reckoned with a Steal effect.

Angina Pectoris↗
PubMed1976

Inhibition of feline collateral vessel development following experimental thrombolic occlusion.

We compared development of feline hindlimb collateral circulation after acute occlusion of the terminal aorta by ligation, thrombus formation, and formation of a "closed" aortic loop containing thromboplastin. Collateral circulation development was assessed by aortograms, scintillation scans, neurological signs following occlusion, measurement of hindlimb muscle blood flow, and forelimb and hindlimb temperature. In cats in which aortic occlusion was the result of ligation or thromboplastin in the aortic loop, paralysis was not evident. Aortograms and scintillation scans indicated hindlimb blood flow. Both muscle temperature and blood flow data indicated that the return of blood flow was rapid. The 5th lumbar artery appears to be the origin of the collateral vessels. The mid-zone component is a dorsal and ventral vertebral route and an epaxial muscle route. The reentry components are the 6th or 7th lumbar arteries. The collateral vessels arise from preexisting collateral vessels. Of those cats in which aortic occlusion was the result of a thrombus, all exhibited paralysis. Aortograms, scintillation scans, muscle temperature, and hindlimb blood flow data indicated reduced hindlimb blood flow. The results suggest that the thrombus has an inhibitory effect on the development of collateral circulation.

Acute Disease↗
PubMed1977

Bronchopulmonary circulation in d-transposition of the great arteries: possible role in genesis of accelerated pulmonary vascular disease.

Hemodynamic and angiograhic data from 209 patients with d-transposition of the great arteries were reviewed to estimate the incidence of prominent bronchopulmonary circulation and to explore its role in the genesis of accelerated pulmonary vascular disease in these patients. The degree of bronchopulmonary circulation was assessed visually by considering the extent of the pulmonary arterial opacification and the circulation to the left atrium. An initial survey study revealed a marked degree of collateral circulation in 20 of 138 patients with d-transposition having cardiac catheterization before age 2 years at the Hospital for Sick Children, Toronto, between 1967 and 1972. Detailed analysis of 71 additional patients with d-transposition aged 1 week to 72 months (mean 17 months) studied at Children's Memorial Hospital, Chicago, between 1967 and 1974 showed collateral circulation of marked degree in 23 and of mild degree in 14. The bronchopulmonary collateral vessels were more freqently demonstrated in the patients with intact ventricular septum than in those with ventricular septal defect or left ventricular outflow tract stenosis. In a prospective study in 12 of 15 patients during cardiac catheterization the functional patency of the bronchopulmonary collateral circulation was demonstrated by obstructing pulmonary blood flow in the right or left pulmonary artery, or both, with an inflated balloon and obtaining from the pulmonary arterial segment distal to the occlusion blood with an oxygen saturation similar to that of the aorta. A hypothesis is presented concerning the role of systemic hypoxemia and local pulmonary hypoxemia induced by way of the bronchopulmonary collateral vessels and the bronchial arterial vasovasorum in promoting pulmonary vasoconstriction. It is suggested that increased pulmonary blood flow and pressure due to the physiologic features of ventricular septal defect, patent ductus arteriosus or transposition of the great vessels, in the face of this regionally increased hypoxemia results in accelerated pulmonary vascular disease.

Aortography↗
PubMedDate not supplied

Selective MR angiography and intracranial collateral blood flow.

This study evaluates the usefulness of MR angiography (MRA) in analyzing the individual collateral flow dynamics and anatomy of the circle of Willis in patients with high-grade extracranial carotid stenosis or occlusion. Selective MRA of the carotid or vertebrobasilar territory was performed by means of presaturation of up to three of the brain-supplying arteries at the level of the middle or lower neck (angled presaturation slabs). Results obtained with selective and nonselective arterial MRA in 45 consecutive patients were compared with findings at transcranial Doppler ultrasonography and intraarterial angiography, the latter serving as the "gold standard." Sensitivity of selective MRA in detecting intracranial collateral circulation via the anterior and posterior communicating artery was 95 and 97%, respectively; sensitivity in depicting extracranial to intracranial transorbital flow was lower (67%). Nonselective arterial MRA was 100% sensitive in detecting a nonfilling of the horizontal (A1) segment of the anterior cerebral artery and in identifying an origin of the posterior cerebral artery from the intracranial carotid artery. Visibility of the posterior communicating artery at MRA predicted for pathological collateral flow via this vessel in all cases. We conclude that selective and nonselective MRA of the cerebral arteries as used here is the most powerful noninvasive method to demonstrate collateral circulation via the basal communicating arteries and to identify hemodynamically relevant anatomic variants of the circle of Willis.

Adult↗
PubMed2000

[A case of distal posterior cerebral artery aneurysm associated with occlusion of the internal carotid artery].

Hemodynamic stress is considered one of the most important factors in the growth of cerebral aneurysms. The authors report a rare case of cerebral aneurysm located at the distal posterior cerebral artery (PCA) in which collateral circulation developed due to occlusion of the internal carotid artery (ICA). A 73-year-old male was admitted to our hospital with a sudden headache and nausea. Computerized tomography (CT) revealed an intracerebral hematoma in the right parieto-occipital lobe and the acute subdural hematoma in both the cerebral interhemispheric fissure and the convexity. Moreover, angiography revealed a saccular aneurysm at the P4 portion of the PCA. The right ICA was occluded at the cervical portion and collateral circulation which had developed in the PCA was extended to the region of the right middle cerebral artery. The aneurysm was clipped 15 days after admission without new neurological complications. This case demonstrates that increased hemodynamic stress plays a role in the growth and rupture of cerebral aneurysm.

Aged↗
PubMed1999

Determinants of collateral development in patients with acute myocardial infarction.

BACKGROUND: The presence or absence of collateral circulation to the infarct-related coronary artery in acute myocardial infarction (AMI) significantly impacts on infarct size and resulting left ventricular function. However, the determinants of collateral development have not been clarified. HYPOTHESIS: The purpose of this study was to elucidate the determinants of collateral development in humans. METHODS: The study group consisted of 248 patients (178 men, 70 women; mean age 63 years) undergoing coronary angiography within 12 h after the onset of a first AMI. All patients exhibited complete occlusion of the infarct-related artery. The extent of collateral circulation to the area perfused by the infarct-related artery was graded as none, or poorly or well developed, depending on the degree of opacification of the occluded coronary artery on the contralateral injection of contrast. RESULTS: Well-developed collateral circulation was observed in 92 of the 248 patients (37.1%). The prevalence of well-developed collaterals was 57% in patients with a history of angina pectoris prior to AMI, which was significantly (p < 0.0001) higher than the 26% in those without a history of angina. Multivariate stepwise logistic regression analysis was then applied to identify predictors of collateral development. Possible determinants of collateral development were long-standing preinfarction angina, severity of coronary artery disease, age, gender, and coronary risk factors (hypertension, diabetes, hypercholesterolemia, smoking). This analysis revealed that only the presence of a history of angina pectoris prior to AMI was a significant predictor of collateral development (p < 0.0001). CONCLUSIONS: A history of angina pectoris prior to AMI is a clinical marker for coronary stenoses. Since severe coronary stenoses can provide stimuli that lead to collateral development, it is reasonable that a history of angina would also be a clinical marker for collateral vessels.

Age Factors↗
PubMed1975

[The value of laparoscopy in the study of portal hypertension].

Up to now, laparoscopy has always been considered as only marginally importan in the study of portal hypertension whereas in fact it should become one of the fundamental examinations in this field. The technique not only contributes, by direct liver exploration, to a more precise judgment regarding the underlying disease, with the possibility of earlier recognition of pre-hepatic, intra-hepatic and post-hepatic forms of portal hypertension, but also makes it possible to detect the earliest signs of hypertension. Further, and most important, laparoscopy extends investigation of the collateral circulation to the sector of the small peritoneal vessels which are inaccessible with other techniques, demonstrating alterations are of decisive importance in the economy of the collateral circulation. On the basis of these new elements, together of course with radiological and fibro-endoscopic data, it is possible to divide cases of portal hypertension into three groups depending on the type of collateral circulation operative on each occasion. These types present differing anatomcfunctional features and clinical physiognomy, a factor of great practical importance especially for the purpose of establishing indications for the portacaval anastomosis of choice, and possibly prophylactic intervention.

Collateral Circulation↗
PubMed1995

[Bilateral occlusion of the internal carotid arteries. Analysis of a series of 19 patients].

The natural history of patients suffering from bilateral internal carotid occlusion is poorly known. We report a study of 19 patients presenting such a vascular condition as demonstrated by angiography. In all our cases, cardio-vascular risk factors were frequently found. Smoking was particularly frequent and present in 18 patients (95%). Presenting neurological episodes included either transient ischemic attack (8/19) or stroke (9/19). Associated arterial lesions were diffusely distributed on the other cerebral vessels, frequently involving the extra-cranial part of the vertebral arteries. Collateral circulation feeding the intracranial carotid system mainly, or exclusively, originated from the vertebro-basilar system. Ischemic strokes were frequently detected by cerebral CT scan. They were located in the middle cerebral territory or at the junctions between 2 major cerebral arteries. A radiological aspect of cortical atrophy was noted in 9 patients among 19. Regional cerebral blood flow assessed by Xe133 inhalation was usually normal at rest (16/19), but hyporeactivity to acetazolamide was found in 10 patients among 19. The latter was more frequent in patients suffering from arterial hypertension or diabetes mellitus. Our results confirm that the patients suffering atheromatous bilateral occlusion of the internal carotid arteries may survive with minimal neurological deficits. Collateral circulation is mainly provided by the vertebro-basilar system allowing to frequently maintain normal cerebral blood flow at rest.

Aged↗