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PubMed1983

Anterior collateral circulation in the primate eye.

Sequential microdissection and scanning electron microscopy of whole primate ocular lumenal methyl methacrylate corrosion castings were performed to determine the anatomic basis of collateral arterial blood flow to the anterior uvea. Collateral anastomoses were observed at three sites: (1) the episclera where the anterior ciliary arteries interconnect at the limbus to form the episcleral circle; (2) the ciliary muscle where anastomoses between the perforating anterior ciliary and long posterior ciliary arteries comprise the intramuscular circle, the most extensive of the three collateral arterial rings, and (3) the root of the iris where circumferentially oriented vessels derived from the intramuscular circle form the "major arterial circle". Of these, the "major arterial circle" is the most discontinuous. This multilevel collateral system probably accounts for the rarity of anterior segment ischemia following all but the most extensive extraocular muscle surgeries.

Anatomy↗
PubMed1978

Pressure-flow characteristics of the coronary collateral circulation during cardiopulmonary bypass. Effects of ventricualr fibrillation.

Even though ventricular fibrillation is used frequently during cardiopulmonary bypass (CPB), the effects of fibrillation on myocardial regions supplied by collateral vessels have not been determined. To study these effects, nine dogs with left ventricles (ameroid model) consisting of a region of myocardium supplied by collateral vessels (CR) and a region supplied by normal coronary arteries (NR) were subjected to normothermic CPB at two perfusion pressures. In both the empty beating heart (EBH) and empty fibrillating heart (EFH) regional myocardial flow was determined by tracer microspheres. Retrograde coronary pressure was measured via cannulation of the circumflex artery distal to the ameroid induced occlusion. When perfusion pressure was maintained at 80 mm Hg, retrograde coronary pressure was similar in the EBH (46 +/- 4 mm Hg) and in the EFH (48 +/- 3 mm Hg). During fibrillation subendocardial flow in the CR was unchanged, while flow in the NR increased (P less than 0.02). In addition, the endo/epi was greater in the NR than in the CR (P less than 0.01), a difference which did not exist in the EBH. The flow response to fibrillation in the CR could be produced in the NR by reducing the perfusion pressure to 50 mm Hg. These data suggest that during CPB, fibrillation exaggerates existing subendocardial perfusion deficits in collateral regions and the impaired flow response appears to be related to a low regional intravascular pressure.

Animals↗
PubMed1984

[Development of collateral circulation in arterial occlusions in advanced age].

Plethysmographic course controls in 15 male patients at the age between 70 and 76.5 years showed that the maximum of the collateral blood supply in arteriosclerosis in the femoral region is reached 1-2 years at the latest after vascular occlusion. The peak-flow-values measured confirm the possibility of efficient collaterals also at older age. When there is a bad early compensation of the artery occlusions, we intended to test in time, whether or not a percutaneous transluminal angioplasty or a local thrombolysis are possible. Furthermore, in 100 male patients with arteriosclerotic disturbances of the blood supply of the legs the plethysmographic measurement of the reactive blood supply showed that the internationally usual haemodynamic subdivision into degrees of severity also concerns the age group between 60 and 75 years. With progressing Fontaine-stage a decrease of the reactive blood supply (first-flow, peak-flow) and an increase of the peak-flow-time were found.

Aged↗
PubMed1986

[Importance of collateral circulation for compensating for myocardial ischemia during physical loading in ischemic heart disease patients].

Exercise-induced electrocardiotopographic ST depression was analysed with reference to the presence of a collateral blood flow, angiographic assessment of the coronary bed and a history of myocardial infarction in 94 coronary patients. The presence of a collateral blood flow is shown to contribute to a more rapid elimination of post-exercise myocardial ischemia, irrespective of the number of affected coronary arteries and the history of myocardial infarction. Myocardial ischemia developing in response to exercise is particularly extensive in case of multiple coronary arterial lesions and the presence of a collateral blood flow.

Adaptation, Physiological↗