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Results for “Collateral Circulation”

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At least 1,207 records · Page 67Linked to original sources
PubMed1975

Pharmacoangiographic evaluation of the hemodynamic significance of coronary artery stenoses.

Acute stenoses of varying degree were produced in the circumflex arteries of 5 calves, and chronic stenoses which reduced blood flow by about 50% were effected in the left anterior descending coronary arteries of 14 dogs. Selective vasodilators or amyl nitrite increased blood flow more than 100% in nonstenotic arteries, but less in stenotic ones. Increased transstenotic blood flow was associated with an increased pressure gradient and increased frequency of collateral circulation. Collateral circulation was sometimes recognizable when the pre- and postvasodilatory angiograms were compared but not when the angiograms were examined individually. The altered flow patterns demonstrated by comparative studies may be a very sensitive index of collateral circulation.

Adenosine↗
PubMed1975

Saphenous vein bypass grafting. Changes in native circulation and collaterals.

One hundred patients were evaluated 12 to 43 months after saphenous vein bypass surgery. The rate of progression of obstructive disease in the native vessels and changes in collateral circulation were analyzed in detail. Fifty-five per cent of preoperatively patent vessels showed progression proximal to the site of graft insertion, 40% proximal to patent grafts; there was distal progression in only 7% of grafted vessels. The progression rate for nongrafted vessels was 14%. Patent grafts were associated with a high rate of disappearance of collaterals to the grafted vessels, while occluded grafts were associated with preservation of collaterals or appearance of new collaterals. Progression of obstructive disease in the native circulation and changes in collaterals did not prevent symptomatic improvement (93% of patients were symptomatically improved).

Adult↗
PubMedDate not supplied

Relationship between contractile reserve, Tl-201 uptake, and collateral angiographic circulation in collateral-dependent myocardium: implications regarding the evaluation of myocardial viability.

BACKGROUND: The aim of this study was to compare collateral angiographic circulation (CC), thallium 201 single photon emission computed tomography (SPECT), low-dose dobutamine echocardiography (LDDE), and their combination in identifying viable myocardium beyond a chronic occlusion. METHODS AND RESULTS: We studied 33 consecutive patients with a chronic occluded coronary artery and regional ventricular dysfunction who underwent dobutamine infusion (5-10 microg x kg(-1) x min(-1)), Tl-201 SPECT, and coronary revascularization (15 patients underwent coronary artery bypass grafting and 18 patients percutaneous transluminal coronary angioplasty). Echocardiography and Tl-201 SPECT at rest were repeated 90 +/- 48 days after revascularization. For viability assessment, Tl-201 SPECT showed the best sensitivity and accuracy (77% and 72%, respectively) compared with LDDE (64% and 63%, respectively) and CC (74% and 55%, P < .05 vs Tl-201 SPECT). Specificity was significantly better for both Tl-201 SPECT (65%) and LDDE (62%) compared with collateral circulation (27%, P < .001 vs Tl-201 SPECT and LDDE). Furthermore, combined Tl-201 SPECT and LDDE data improved specificity (from 88% to 92%) and positive predictive power (from 75% to 78%) but not global accuracy. A direct relationship between the number of viable segments and global functional recovery after revascularization was found only in the case of Tl-201 SPECT (r = 0.48, P = .04). CONCLUSIONS: This study demonstrates that CC has a very low specificity in the evaluation of viability in collateral-dependent myocardium and that LDDE has a very low sensitivity, whereas Tl-201 SPECT is the most reliable method, particularly in akinetic segments, and optimally identifies patients who will mostly benefit from revascularization in terms of ventricular functional improvement. No additional advantages in terms of accuracy were found when Tl-201 SPECT and LDDE data were combined.

Aged↗
PubMedDate not supplied

[Evaluation of blood supply dynamics and possibilities of cerebral arteriovenous malformations (AVM) imaging by means of transcranial color-coded duplex sonography (TCCS)].

The present study was carried out in 12 patients (7 males and 5 females) aged 16-56 years (mean age 35.9) with arteriovenous malformation diagnosed in cerebral angiography. The examination was performed by means of ATL ULTRAMARK 9 with low-frequency (2MHz to 3MHz) transducer. Assessment was made of possibilities of imaging arteriovenous malformations by transcranial colour-coded duplex sonography and of blood flow values in the studied intracranial arteries. Statistical analysis was applied of the following blood flow parameters: mean velocity, peak systolic velocity, end diastolic velocity, pulsatility index (PI), resistance index (RI), pulsatility transmission index (PTI) and relative flow velocity (RFV). The malformations were imaged using TCCS in 9 (75%) patients. In two-dimensional B mode image the angiomas displayed echogenicity similar to the surrounding brain parenchyma and could not be precisely delineated. The colour-coded imaging made possible depicting the image of the vessel loops in the AVM nidus. In two other patients the presence of angiomas was confirmed by blood flow disturbances in the feeder vessel: increased blood flow, decreased pulsatility and resistance indices, and collateral circulation. Collateralization by the contralateral internal carotid artery via the anterior communicating artery was disclosed in 9 cases. The TCCS results corresponded closely to angiographic findings. Collateral circulation via the posterior communicating artery ipsilateral to the AVM was found in 3 of 5 patients in whom it was diagnosed in cerebral angiography. Doppler findings in the patients were similar to the conventional TCD examination. In the feeding vessels significant increase in blood flow velocity and decreased pulsatility and resistance indices was observed. RFV value for the end diastolic velocity was higher than RFV for the peak systolic velocity (p < 0.001) and mean velocity. These findings suggest that the increased end diastolic velocity in the feeding vessel is higher than the mean velocity and peak systolic velocity. It is thought that the TCCS can be successfully used in early diagnosis of cerebral arterio-venous malformations and as an instrument in follow-up examination.

Adolescent↗
PubMed1983

Effects of cardiac contraction on segmental coronary resistances and collateral perfusion.

This study examined the reactions of coronary arteries and microvessels to changes in left ventricular pressure, as well as their significance for collateral circulation. Collateral perfusion pressure was measured as peripheral coronary pressure of an occluded coronary artery after embolisation of its terminal vascular bed with 20 micron microspheres in 9 anesthetized dogs. With measurement of collateral perfusion pressure it was then possible to determine the segmental coronary resistances of the coronary arteries and the microvasculature. Left ventricular pressure was increased by aortic clamping during autoregulation and after maximal pharmacological dilation of the coronary circulation. During autoregulation, the increase in left ventricular pressure induced a resistance decrease mainly in the postcollateral microvessels. With maximal vasodilation, the increase in left ventricular pressure induced a resistance increase mainly in the postcollateral microvessels. Finally with ventricular fibrillation, the resistance of the postcollateral microvasculature was markedly decreased. We conclude that both metabolic regulation of coronary blood flow and extravascular compression of coronary circulation by cardiac contraction act predominantly on postcollateral microvessels. Coronary collateral circulation may be impaired at increased left ventricular pressure.

Animals↗
PubMed1985

Coronary angiographic significance of left anterior fascicular block during acute myocardial infarction.

The clinical and angiographic significance of isolated left anterior fascicular block occurring during the early stage of acute myocardial infarction was studied in 141 consecutive patients who underwent cardiac catheterization before hospital discharge. Left anterior fascicular block occurred in 15 of the 62 patients with an anterior wall infarction and in 13 of the 79 with an inferior infarction. None of the clinical characteristics differed among patients with or without left anterior fascicular block. The number of coronary vessels with significant stenosis, the Friesinger and the Gensini scores for severity of stenosis and the ejection fraction were also similar in the two groups. Patients with left anterior fascicular block had more severe narrowing of the coronary artery supplying the infarct zone (88 +/- 21 versus 70 +/- 35%, p less than 0.001) and tended to have less developed collateral circulation (collateral score 0.7 +/- 0.8 versus 1 +/- 0.8, p = 0.10). A significant stenosis of the left anterior descending coronary artery was found as frequently in patients with as in those without left anterior fascicular block (64 versus 65%); 29% of the patients with inferior wall infarction and left anterior fascicular block had left anterior descending coronary artery stenosis compared with 47% of the patients without this conduction disturbance (no significant difference). When the infarction was located anteriorly, a significant stenosis of the proximal segment of the left anterior descending coronary artery was present in 47% of the patients with and in 45% of the patients without left anterior fascicular block.(ABSTRACT TRUNCATED AT 250 WORDS)

Bundle-Branch Block↗
PubMed1990

Actions of isoflurane on myocardial perfusion in chronically instrumented dogs with poor, moderate, or well-developed coronary collaterals.

The influence of isoflurane on myocardial perfusion (determined by the radioactive microsphere technique) in normal regions and areas distal to a left anterior descending (LAD) coronary artery occlusion was evaluated in dogs that were chronically instrumented for measurement of systemic and coronary hemodynamics and had varying degrees of coronary collateral development. In 17 dogs, an Ameroid constrictor was implanted on the LAD coronary artery to produce a slowly progressive occlusion that stimulated development of the collateral circulation. Collateralization was allowed to progress in three groups of dogs to a poor (3 +/- 1 days), moderate (19 +/- 4 days), or well-developed (50 days) stage postsurgery. After the indicated period of time had elapsed, the LAD coronary artery was occluded (via Ameroid constrictor and/or balloon cuff occluder). Radioactive microspheres were administered during the conscious state and at 2% and 3% inspired concentrations of isoflurane. A fourth set of microspheres was injected at 3% isoflurane with heart rate and blood pressure adjusted to conscious levels. Isoflurane produced equivalent changes in systemic hemodynamics in all groups, including an increase in heart rate and decreases in arterial pressure and left ventricular peak positive dP/dt. Regional contractile function of normal myocardium was reduced by isoflurane in all groups. Isoflurane (3%) significantly decreased subepicardial, subendocardial, and transmural blood flow in normal and collateral-dependent regions in all groups. Myocardial perfusion returned to levels present in the conscious state when arterial pressure and heart rate were adjusted to those levels present prior to induction of anesthesia. Neither the left ventricular transmural distribution nor the collateral-dependent to normal zone flow ratio was altered from conscious levels by isoflurane in any group with or without changes in blood pressure and heart rate. The results indicate that isoflurane does not redistribute coronary blood flow from collateral-dependent to normal regions in a single-vessel coronary artery disease model. The actions of isoflurane are also independent of the degree of coronary collateral development.

Anesthesia, Inhalation↗
PubMed2003

Obesity is associated with impaired coronary collateral vessel development.

BACKGROUND: Chronic myocardial ischaemia due to coronary artery stenosis or occlusion has been shown to increase the growth of coronary collateral circulation. Collateralization leads to increased oxygen delivery to the area at risk and hence may reduce ischaemia, prevent infarction and preserve contractile function. However, there is considerable variation among patient subsets in terms of the presence or degree of collateralization. We aimed to evaluate the relationship between obesity and coronary collateral development in patients with ischaemic heart disease. METHODS AND RESULTS: In all, 215 patients (mean age, 57.8+/-8.9 y) with body mass index (BMI)> or =30 kg/m(2) were enrolled into our study. A total of 90 age- and sex-matched patients (mean age, 58.7+/-10 y) with BMI<25 kg/m(2) and significant coronary artery disease were selected as a control group. The mean age and distribution of risk factors for coronary heart disease were not significantly different between two groups other than poorer HDL cholesterol and triglyceride profile in obese patients. The mean BMI was significantly higher in the patient group (33.3+/-2.4 vs 22.8+/-1.7, P<0.001). The mean number of diseased vessels and maximum lesion severity were not significantly different between the two groups. The mean Rentrop collateral score of the patient group was significantly worse than the control group (1.08+/-0.68 vs 2.10+/-0.72, P<0.001). CONCLUSIONS: Our findings suggest that collateral vessel development is poorer in obese patients (defined as BMI> or =30 kg/m(2)) with ischemic heart disease compared to normal range BMI, and the risk of having poor collateral vessel development is significantly increased. However, this might be reflecting the cluster of risk factors, associated with metabolic syndrome, in which insulin resistance plays a major role.

Age Distribution↗
PubMed1987

Improvement of cerebral circulation by extracorporal collateral between the femoral and the external carotid artery in experimentally induced ischaemia.

The purpose of this study was to examine the effect of extracorporal collateral circulation (ECCC) between the femoral and the external artery (ECA) on the cerebral circulation, in experimentally induced ischaemia, in rabbits. The animals were divided in four groups. Seven animals (Group A) were used to determine the injection pressure (150-160 mmHg) at the ECA, necessary to achieve collateral circulation between ECA and internal carotid artery (ICA), after occlusion of ICA. Group B (8 rabbits) was the control group for establishing cerebral ischaemia (CI) by a) ligating the common carotid artery bilaterally, b) coagulating the right vertebral artery and c) exsanguinating the animal (removing 28-30 ml of blood). The induced ischaemia was studied by BP and PCO2 monitoring, CBF measurement, videomicroscopy of surface cerebral vessels, and finally macroscopic and microscopic examination of brain sections. In group C (8 animals)-moderate degree of CI-brain circulation improved in all animals after the application of the ECCC, installed at 135 min after the onset of CI. In 10 animals (group D) with severe and prolonged (225 min) CI, ECCC enhanced the brain circulation in eight animals to a variable degree.

Animals↗
PubMedDate not supplied

[Functional significance of collateral coronary circulation in univascular obstructions (1)].

The presence, degree and functional significance of the coronary collateral circulation was investigated in a group of 68 patients with angiographycally important (greater than 60%) univascular coronary obstruction. The following clinical parameters were reviewed. Smoking, hypertension, diabetes mellitus, functional class (NYHA), and degree of angina pectoris. In the ECG the presence of abnormal Q waves and the response to the stress test were analysed. To evaluate the functional significance of the collateral circulation the following angiographic and hemodynamic parameters were measured: ejection fraction (FE 100), mid sistolic ejection fraction (FE 50), percent of regional shortening of the left ventricular wall and finally the end diastolic pressure. According to the obstructed vessel (R, DA, Cx) the degree of obstruction (parcial or complete) and the degree of collateral circulation (O, I, II, III) several groups were formed. Statistical analysis of all the above mentioned clinical, electrocardiographic and angiographic findings were compared amongst the various groups. Coronary collateral circulation was demonstrated in 45 patients (68%) being present in 82% of those with complete coronary obstruction. In most of the patients (87%) an abundant collateral network was present (grade II or III). No statistical differences were demonstrated between the groups with abundant or poor collateral circulation in all the clinical, electrocardiographic or angiographic parameters. Finally we conclude that important collateral circulation usually develops in the presence of severe coronary obstruction; however its functional value is limited.

Adult↗