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The presence of an intrarenal collateral circulation in pediatric patients with segmental renal artery stenosis has not been stressed. Three patients demonstrating these collateral pathways are presented. The anatomy, pathogenesis, angiographic features, differential diagnosis, and significance of intrarenal collaterals in infants and children are discussed.
The development of collateral circulation was studied in a replanted rat hindlimb model by use of the hemodynamic techniques of hydrogen washout and laser Doppler capillary perfusion monitoring. Collateral development occurred and provided blood flow whose magnitude increased linearly over time. Twenty-seven percent of preligation blood flow was present at 2 weeks after replantation, 39% at 4 to 5 weeks, and 77% at 8 to 9 weeks by laser Doppler assessment. Laser Doppler correlated more closely with limb survival than did the hydrogen washout technique. Uniform necrosis (eight of eight) occurred after pedicle interruption in the 2-week group. Partial limb survival was noted in five of eight replants at 4 to 5 weeks on transection of the vascular pedicle, while complete survival of all replants (nine of nine) was seen at 8 to 9 weeks.
Vascular casts were prepared using Batson Anatomical corrosion compound, from maximally dilated rat tibialis anterior (TA), extensor digitorum longus (EDL) and soleus (SOL) with normal and limited blood supply (unilateral ligation of the common iliac artery). The weight of casts was expressed as a percentage of muscle wet weight. This value was considered representative for the size of the vascular bed. The value was 2.9 +/- 0.12% (mean +/- SEM) in normal TA, 3.37 +/- 0.15% in EDL and 4.8 +/- 0.43% in SOL. The weight of vascular casts decreased in all muscles to 40% of the values found in the contralateral muscles one week after ligation. Five weeks after ligation, it was about 60% of the control values in TA and EDL, and 80% in SOL. Treatment with torbafylline for one week did not change the weight of the vascular casts. After five weeks the size of the vascular bed was back to control values in EDL and SOL, and only 20% lower than control muscles in TA. This could be attributed to improved development of collateral circulation. Treatment with pentoxifylline improved collateral circulation only in SOL.
The angiocardiograms of 17 patients with aortic arch interruption are reviewed to emphasize the variations in arch interruption and origin of the brachiocephalic vessels, and collateral circulation to the descending aorta. Depending on the anatomical type and subtype of arch interruption, collateral flow to the descending aorta in the presence of a stenotic or closed ductus will be dependent on the development of intercostal collaterals and/or the presence of retrograde flow in all brachiocephalic vessels arising from the descending aorta. Familiarity with the potential pathways for collateral circulation may permit differentiation into types and subtypes on chest radiograph. Patients with Type I interruption may have bilateral rib notching if the right subclavian artery originates normally from the innominate artery, but will have rib notching confined to the left side if the origin of the right subclavian artery is aberrant. Type II or Type III interruption patients will have rib notching confined to the right side if the right subclavian has a normal origin, but no rib notching if the origin of the right subclavian artery is aberrant.
The myocardial perfusion and left ventricular function were evaluated by bicycle ergometry and myocardial scintigraphy in 23 patients with primary angina taking into account the status of coronary collateral circulation in response to stenotic and occlusive atherosclerosis. In addition to severe occlusive disease of the coronary bed, most patients had significant disturbances of myocardial perfusion and left ventricular function, which were detected during exercise tests. In patients with compensatory collateral circulation in the coronary bed, such disturbances were less marked than in those without anastomoses. However collateral coronary circulation cannot be regarded to be of real value as it compensates impaired perfusion incompletely, but in some cases it can result in impaired myocardial vascularization apparently due to the steal syndrome.
Three cases with cerebral ischemic symptoms and an intracranial aneurysm are presented. Using [99mTc]hexamethyl-propyleneamine oxime (HM-PAO) single photon emission computed tomography imaging before and during the Matas test, a quantitative measurement method was developed for evaluating brain collateral circulation. The evaluation correlated well with findings of contrast carotid angiography. This noninvasive method seems to be useful for selection of patients for appropriate surgical treatment.
In this report, a patient is described with an occluded left circumflex artery, in whom the corresponding myocardium was protected at rest by sufficient collateral circulation. Because of angina pectoris class III, a PTCA of that occluded vessel was performed, complicated by a large dissection. Recruitable collateral flow, assessed from pressure calculations by a new technique, suddenly decreased at the very moment of dissection. This was accompanied by resting pain and ischemia on the ECG. This case report confirms the hypothesis that the collateral circulation can be damaged by PTCA and emphasizes that every PTCA implies a definite risk, even in case of an occluded coronary artery filled by collaterals.
In isolated vascular rings, we have shown that mature coronary collateral vessels are highly responsive to the vasoconstrictor effects of vasopressin. The purpose of the present study was to determine the effect of concentrations of vasopressin encountered in pathophysiologic states on the collateral circulation in vivo. We studied eight open-chest anesthetized dogs with mature coronary collateral vessels 3-6 months after placement of an ameroid constrictor on the left circumflex coronary artery. The left anterior descending coronary artery was perfused at constant pressure, and peripheral coronary pressure was monitored continuously throughout each experiment. At baseline and during intracoronary infusion of vasopressin, which resulted in concentrations ranging from 8 +/- 3 to 1,340 +/- 327 microM/ml, we measured regional myocardial perfusion with radiolabeled microspheres. At baseline, regional myocardial perfusion to the collateral-dependent myocardium and to the normally perfused myocardium was similar; however, during vasopressin infusion, collateral-dependent zone flow decreased by 49 +/- 14% whereas normal zone flow decreased by only 9 +/- 9% (p less than 0.0005, normal zone perfusion vs. collateral perfusion). Vasopressin increased transcollateral resistance by 242 +/- 95% above baseline but produced a more modest increase in normal zone resistance (15 +/- 10%). The subendocardial to subepicardial perfusion ratio increased by 28 +/- 12% in the normal zone in response to vasopressin but decreased by 18 +/- 11% in the collateral-dependent zone. These data show that mature coronary collateral vessels are responsive to the vasoconstrictor effects of vasopressin at concentrations encountered in various pathophysiologic states.(ABSTRACT TRUNCATED AT 250 WORDS)
Surgical preparation of the rat cremaster skeletal muscle for microvascular study usually involves occlusion of the deferential artery and vein which supply a collateral circulation to the tissue. This allows removal of the testis and ductus deferens, and permits direct observation of the cremaster microvasculature. We examined with intravital microscopy the effect of this occlusion on alpha-adrenergic and nonreceptor-mediated (KCl) constriction of large arterioles (1A, 136 microns i.d.) and venules (1V, 193 microns i.d.). The acutely denervated cremaster was suspended in a tissue bath containing propranolol to block beta-adrenergic receptors. alpha 1-adrenergic (norepinephrine (NE) + rauwolscine), alpha 2-adrenergic (NE + prazosin), and KCl (+ phentolamine) concentration-response curves were obtained for bath-added agonists before vs after occlusion of the deferential circulation. Occlusion had no effect on baseline 1A diameter but increased 1V diameter slightly. Arteriolar alpha 1- and alpha 2-adrenergic sensitivities were unaffected by occlusion, but venular sensitivities were reduced by the same amount (approximately fourfold) for both receptor types. Occlusion increased arteriolar sensitivity to KCl but had no effect of venular KCl sensitivity. These data indicate that occlusion of the deferential collateral circulation can produce significant and varied effects on alpha-adrenoceptor and nonreceptor-mediated constriction of cremaster large arteriolar and venular smooth muscle, and underscore the need to avoid collateral occlusion for certain studies of the cremaster microcirculation.
The significance of coronary collateral circulation for redistribution in the infarcted zone was evaluated in 16 patients with history of myocardial infarction and severe stenosis (> or = 90%) of the coronary artery. Redistribution areas were quantitatively measured using the redistribution ratios and redistribution indices on the infarction-redistribution map obtained by thallium-201 scintigraphy with single photon emission computed tomography. Coronary collateral findings were categorized in 4 classes according to the Rentrop's grading. There was good, positive linear correlation between the redistribution ratio (Y) and collateral grading (X) (Y = 0.21X + 0.10, r = 0.92, p < 0.01). The redistribution index (X) also correlated well with the collateral grading (Y) using a good, positive quadratic equation (Y = 0.32X2 + 0.24X + 0.04, r = 0.89, p < 0.01). These results suggest that the measurements of the redistribution areas in the ischemic zone in myocardial infarction correlated well with collateral perfusion. Collateral perfusion severer than Rentrop's grade 2 markedly reduces the severity of ischemia and increases redistribution areas.
The present study was performed to investigate whether coronary collateral vessels open immediately after occurrence of myocardial ischemia. Multistage bicycle exercise was performed to determine the maximum tolerable workload until the onset of angina and significant ST segment depression in 10 patients with well-developed collateral circulation. On a different day, exercise using the maximum tolerable workload was repeated for comparable exercise durations. In two of the 10 patients, anginal pain was gradually alleviated despite the continuation of exercise using the fixed workloads. The extent of ST segment depression during three min exercise with the fixed workload was 0.20 +/- 0.10 (SD) mV, which was significantly (p less than 0.05) greater than 0.16 +/- 0.08 mV at the end of exercise with fixed workload. By contrast, the pressure-rate product was smaller at three min than at the end of exercise using the fixed workload (20,900 +/- 5,500 vs 22,700 +/- 5,700 mmHg-beats/min; p less than 0.05). It was concluded that delayed collateral openings play a critical role in the pathogenesis of the walk-through phenomenon.
A review of data in 465 patients with complete obstruction of either the left anterior descending or right coronary artery was undertaken to evaluate the functional role of the collateral circulation. Complete obstruction of a dominant right coronary artery was observed in 288 patients, 83 percent with distal filling and visualization of the posterior descending artery by way of collateral vessels. Complete obstruction of the left anterior descending artery was noted in 177 patients, 71 percent with filling and visualization distal to the obstruction by way of collateral vessels. Among patients with obstruction of the left anterior descending artery, there was a significantly greater frequency of congestive heart failure and cardiomegaly in those without collateral vessels than in those with collateral vessels. The former also had a significantly greater frequency of both electrocardiographic evidence of an anterior wall myocardial infarction and angiographic findings of anterior wall asynergy. The frequency of inferior myocardial infarction and inferior wall asynergy was not influenced by the presence of collateral vessels. These observations indicate that the collateral circulation plays a significant protective role in the presence of obstruction of the left anterior descending artery, which is not apparent with obstruction of the right coronary artery.
Experiments were performed on 18 anesthetized open-chest dogs to observe the changes in platelet aggregation and coronary collateral circulation during the early phase of acute myocardial ischemia. An increase in platelet aggregation rates (PAgR) and a decrease in platelet counts (PC) were found in the blood collected from the ischemic myocardium after coronary occlusion. PAgR was increased by 58.7 +/- 5.6% and PC was reduced by 39.5 +/- 23.6% at 50 min after occlusion (P less than 0.01). Under the condition of controlling aortic blood pressure, collateral coronary vascular capacity (CVC) was not changed (P greater than 0.05), but the effective collateral coronary flow to the ischemic zone, calculated by Wyatt et al's equation, was significantly reduced by 23.5 +/- 9.7% at 50 min after occlusion (P less than 0.05). There was a negative correlation between the changes in PAgR and the effective collateral coronary flow ( r = -0.857, P less than 0.01), and between the collateral indices and infarct size (r = -0.847, P less than 0.01). Abnormal changes in parameters of platelet and coronary collateral circulation after myocardial ischemia were nearly abolished by intravenous injection of aspirin before coronary occlusion. The results suggest that the deleterious changes of platelet aggregation during the early phase of the acute myocardial ischemia may decrease the effective collateral coronary flow significantly and thereby enlarge the infarct size.
In patients with cirrhosis, superior portosystemic collateral circulation was evaluated by the continuous thermodilution method in the azygos vein. Azygos blood flow was 5 times higher in a group of patients with cirrhosis (alcoholic in 27, cryptogenic in 8, post-hepatitic in 2 and primary biliary cirrhosis in 1), than in a group of patients without portal hypertension (steatosis in 2, granulomatous hepatitis in 2, persistent chronic hepatitis in 2 and Hodgkin's disease in 1). Azygos blood flow was not different in cirrhotic patients with no visible, in those with small-sized, and in those with large sized oesophageal varices. Azygos blood flow was not different in cirrhotic patients with and without a previous episode of gastrointestinal bleeding. Fifteen min after intravenous administration of 15 mg of propranolol, azygos blood flow significantly decreased whereas azygos blood flow did not change after placebo. The decrease in azygos blood flow was significantly more marked than the reduction in cardiac output. It is concluded that superior portosystemic collateral blood flow is elevated in patients with cirrhosis and that the reduction in this collateral circulation might explain the efficiency of propranolol in the prevention of recurrent gastrointestinal bleeding.
An eleven years' clinical treatment of a 28-year-old tractor-driver with Paget-Schroetter's syndrome is described. The development of the collateral circulation was pursued during 6 years or 11 years, respectively, after the occurence of the vein thrombosis and the importance of phlebography in this rare disease is emphasized for the judgment of the prognosis. Phlebographic procedure is recommended for the reliable evaluation of the pathomorphological changes of the veins and of the developed collateral circulation.
Forty patients with Kawasaki disease with severe coronary sequelae were investigated. All had at least a 90% reduction in the diameter of the major coronary artery. Collateral vessels were seen in 32 of 33 (97%) patients with total occlusion. All patients with severe stenosis but not total occlusion had no or poorly developed collateral vessels. Analysis according to the presence or absence of collateral vessels showed no significant differences in the results of treadmill stress testing and myocardial imaging between these two groups. In patients treated surgically, the abnormalities recognized by these tests were normalized or improved when the bypass was patent. These data indicate that collateral circulation in patients with Kawasaki disease cannot be seen angiographically unless there is total occlusion and the presence of collateral circulation cannot provide protection against stress-induced myocardial ischemia.
OBJECTIVE: To compare four methods of evaluating collateral blood flow to the hand. METHODS: The hands of 74 volunteers on the faculty or staff of a university hospital were studied prospectively. Only subjects without known peripheral vascular disease were included. Four tests were used in random order to assess radial and ulnar artery flow. Results of the assessments using the modified Allen's test, pulse oximetry, plethysmography, and laser Doppler perfusion monitoring were compared. RESULTS: No interrupted palmar arch was found. The modified Allen's test was normal in all cases. Pulse oximetry detected a 5% incidence of noticeably reduced blood flow in one artery compared with the other artery. This dominance of one artery was identified in 69% of the hands by plethysmography. The laser Doppler noted a dominant artery in 64% of the hands. Plethysmography and the laser Doppler disagreed in their findings in only 9% of the hands evaluated. Numerical values of blood flow, attainable only by the laser Doppler, were significantly lower upon occlusion of the radial vs the ulnar arteries (p < 0.05; paired t-test). CONCLUSION: All of the tests provide information about the collateral circulation to the hand. Only the laser Doppler provides quantitative blood flow. Further studies involving subjects most at risk for post-cannulation ischemic injury are needed to guide the clinical application of these findings.
The most important anastomoses between the arteria carotis externa and interna are discussed, based on a study of several patients with obstruction of the arteria carotis interna. When the arteria carotis interna is obstructed, it is important to determine, as best as possible, the collateral circulation to the vessels distal to the occlusion, since the prognosis can partly depend on it, and because collateral circulation must be taken into account in evaluating operative possibilities.