Collateral Function Research Articles

Coronary Collaterals in Full Effect

A 59-year-old man with no relevant medical history was referred to our clinic for analysis of exertional chest pain. He had noticed slowly progressive symptoms approximately 6 months before referral, although they did not prohibit his daily 12-mile cycling exercise routine. During diagnostic 99m-technetium-sestamibi single photon emission computed tomography treadmill stress testing, the ECG showed pathological ST-segment depression, and the patient had anginal chest pain. Three-dimensional reconstructed scintigraphic perfusion images (Figure 1) displayed a substantial reversible defect in the anterolateral myocardium with only a mild resting perfusion defect in the distal segment of the anterior wall, which coincided with a small area of subendocardial fibrosis visualized …

The functional reserve of collaterals supplying long-term chronic total coronary occlusions in patients without prior myocardial infarction

Chronic total coronary occlusions (CTOs) with angiographically well-developed collaterals may be considered to provide sufficient blood supply to the occluded segment, and the indication for revascularization may be questioned. Therefore, the collateral function and functional reserve in patients with a CTO without a prior Q-wave myocardial infarction (MI) were assessed. Invasive assessment of collateral function was done during successful percutaneous coronary intervention in 107 patients with a CTO and no prior Q-wave MI. Intracoronary Doppler flow velocity and pressure recordings were obtained distal to the occlusion before the first balloon inflation and collateral function indexes calculated. In 62 patients, additional pharmacological stress testing was done by intravenous adenosine (140 microg/kg/min) to assess the collateral flow reserve. Patients with normal and impaired regional dysfunction were compared. Collateral function was similar in patients with and without regional left ventricular (LV) dysfunction. In both groups, 78% collaterals provided a collateral pressure index at baseline > 0.3, sufficient to prevent ischaemia during a balloon occlusion, with a minimum of 0.2 in those with preserved LV function. A Doppler-derived function index showed a wider variation due to the high prevalence of microvascular dysfunction in CTOs. Only 7% of patients had an increase in collateral flow reserve > 2.0 during pharmacological stress, whereas coronary steal occurred in one-third independent of regional LV function. A limited increase in collateral flow and the high prevalence of coronary steal during stress underscore the functional limitation of collaterals in CTOs without prior Q-wave MI. Even presumably 'well-collateralized' CTOs may benefit from a revascularization.

Obstructive lesions of the inferior vena cava: Clinical features and endovenous treatment

Chronic obstructions of the inferior vena cava (IVC) are associated with many odd features. Even total occlusions may remain entirely silent or present late with acute symptoms. Renal dysfunction is rare. Many have chronic symptoms, but often only one limb is affected. We describe the clinical features in a series of 120 patients seen over a 10-year period and the results of successful stent placement in 99 limbs. Patients with acute onset of symptoms due to distal thromboses underwent catheter-directed thrombolysis. Patients with significant chronic symptoms were investigated by duplex, venous function tests, transfemoral venography and finally intravascular ultrasound (IVUS). Stenotic segments were balloon dilated and occluded segments were recannalized when feasible; stents were placed under IVUS control. In the asymptomatic group, 10 patients with total occlusions had transient or no occlusive symptoms. In the acute symptom group, four patients with chronic IVC occlusions presented with acute onset of deep venous thrombosis distal to the occlusion but became asymptomatic when the clot was lysed. In the chronic symptom group, 97 patients (99 limbs) had symptoms of chronic venous disease of variable distribution and intensity. In two-thirds, limb symptoms were unilateral. Pathology was total occlusion in 14%, and the rest were stenoses. The lesion extended above the renal vein in 18%. Common iliac obstruction was concurrent in 93%. Distal reflux was present in 66%. Modifications of the basic stent technique were required in recanalization of total occlusions (four extending up to the atrium), two bilateral stent deployments, and nine IVC filter cases. Stent deployment across the renal and hepatic veins or the contralateral iliac vein had no adverse sequelae. Stent patency (cumulative) at 2 years was 82%. Complete relief (cumulative) of pain and swelling at 3.5 years was 74% and 51%, respectively. The cumulative rate of complete ulcer healing at 2 years was 63%. Overall clinical outcome was rated as good or excellent in 70%. The unusual clinical features of IVC obstructions seem related to the rich collateralization, which has an embryonic basis. Common iliac vein patency seems to be a crucial link in collateral function, and its concurrent occlusion produces symptoms. Percutaneous stent placement has an emerging role in the treatment of IVC obstructive lesions, with good mid-term stent patency and clinical results.

Matrix metalloproteinase (MMP) inhibition eliminates training‐induced collateral blood flow expansion in rats

To study the role of MMPs in collateral vessel remodeling, adult male Sprague-Dawley rats with bilateral femoral artery occlusion (n=30) were divided into sedentary (Sed, limited to cage activity, n=10) or treadmill exercise (Tr, 2x/d, 2 wks; n=20). Rats in Sed or Tr group were fed with either water or MMP inhibitor doxycycline (Doxy; ~30 mg/kg/d) for two wks. Hind limb blood flow was determined with isotope labeled microspheres during treadmill running. In Tr animals, Doxy treatment reduced MMP-2 protein content by 19% (Western blot); and proMMP-2 activity by 17% (Zymograph) in the red gastrocnemius muscle when compared with the water controls. Blood pressure (~130 mmHg) and heart rate (~480 bpm) were no difference across the groups during flow measuring. Collateral dependent blood flows to the calf muscle were 48±1.7, 47±8.7, 81±4.1 and 60±3.5 ml/min/100g in Sed+water (n=6), Sed+Doxy (n=4), Tr+water (n=9), and Tr+Doxy (n=8) groups respectively (ANOVA, p<0.001). Maximal luminal diameters of collateral artery (the perforating a.) increased from ~280μm in Sed groups to 317±13.7μm (Tr +water), and reduced to 278±11.3μm by Doxy in the Tr animals. Our results indicate that exercise training-induced remodeling of collateral function and structure requires normal MMP-2 function. Supported by NIH HL-37387.

Transcranial duplex ultrasound of the ophthalmic artery

The purpose of this study was to identify the ophthalmic artery (OA) by means of transcranial color-coded sonography using a new approach via the transtemporal bone window and to compare blood flow measurements with values obtained from the transorbital approach. A total of 105 subjects were included. Two individuals had an insufficient unilateral bone window, according to our inclusion criteria. Of the remaining 208 OAs, 206 (99%) could successfully be insonated via the transorbital approach and 190 (91%) via the transtemporal approach. Transorbital systolic and diastolic flow velocity (FVs) ranged between 15 and 67 cm/s (mean ± SD: 35 ± 10) and 4 to 36 cm/s (14 ± 5), pulsatility index ranged between 0.4 to 2.8 (1.2 ± 0.4). Transtemporal systolic and diastolic FVs ranged between 15 and 58 cm/s (33 ± 9) and 4 to 25 cm/s (11 ± 4). Transorbital and transtemporal FVs correlated significantly ( p = 0.01). Our study demonstrates that transtemporal insonation of the proximal intracranial OA is feasible. Whenever OA assessment for analysis of collateral function is required, this simple approach, avoiding direct eye bulb insonation, should be considered. (E-mail: stephan.schreiber@charite.de)

Is Magnetic Resonance Image Guidance the Key to Opening Chronic Total Occlusions?

Through progressive plaque growth or fibrotic organization of occlusive thrombus, atherosclerosis may result in chronic total occlusion (CTO) of a major arterial conduit. If CTO develops slowly, collateral pathways may supply sufficient perfusion to retain tissue viability despite occlusion of the major inflow conduit. However, such collateral-mediated perfusion rarely matches that provided by an open main conduit, particularly during the peak demand of regional muscular activity. Although strategies to limit regional oxygen demand (eg, β-blockers for the treatment of angina pectoris) or to enhance collateral function (eg, a walking program for superficial femoral occlusion, experimental angiogenesis) may be of some benefit, these approaches generally offer less complete return of normal physiology and relief of ischemic symptoms than does direct revascularization of the occluded vessel. With surgical bypass, the nature of the occlusion (its length, duration, tortuosity, calcification) is less important than the presence of a suitable distal anastomotic target. On the other hand, with catheter-based techniques, success depends heavily on these lesion characteristics. In fact, crossing such occluded segments with a guidewire remains the dominant barrier to catheter-based treatments of occluded arterial segments. Once the guidewire has been passed successfully into the distal true lumen, the process of dilating and stenting the segment is usually straightforward and durable, at least with the use of drug-eluting stents in coronary CTOs.1,2 Article p 1101 Devices designed to cross CTOs should have 3 key features: an ability to distinguish a true luminal path from one created within (dissection) or through (perforation) the vessel wall of the occluded segment, an ability to change direction (steer) to correct deviations from the desired path through the occlusion, and an ability to penetrate the frequently fibrotic and focally calcific substance of the occlusion through the use of either mechanical stiffness or an alternative energy modality (laser, …

The value of phase-contrast magnetic resonance angiography of the circle of Willis in predicting cerebral ischemia-hypoxia (shunt need) during carotid endarterectomy

Cerebral perfusion during carotid cross-clamping depends on collateral function of the circle of Willis. The aim of this study was to determine the value of 3D Phase-Contrast (3D PC) MR angiography in predicting pre-operatively the need of shunting. 3D PC MR angiography were performed in 121 patients before carotid endarterectomy under locoregional anaesthesia. Based on the MR analysis, the risk of cerebral ischemia-hypoxia during clamping was classified as high, moderate and low. The analysis was then correlated with intraoperative neurological examination. In patients with high risk of cerebral ischemia (n=9), immediate cerebral ischemia developed in all patients within one min of clamping (P<0.001). All nine underwent shunt placement. In six of the patients with moderate risk (n=46), cerebral ischemia occurred between 20 and 25 min after clamping; All occurred during intraoperative hypotension. 3D PC MR angiography can significantly determine the need of shunting in patients with important risk of immediate intraoperative cerebral ischemia. It also focuses on the intraoperative blood pressure stability in patients with moderate risk of ischemia.

Collaterals and the recovery of left ventricular function after recanalization of a chronic total coronary occlusion

A good collateral function in patients with regional myocardial dysfunction may indicate viability with the potential for left ventricular (LV) recovery after revascularization of a chronic total coronary occlusion (CTO). A CTO (duration > 2 weeks) was successfully recanalized in 126 patients. During this procedure, the collateral function was assessed before the first balloon inflation by intracoronary Doppler and pressure wires. Collateral function indexes were calculated. Left ventricular function was assessed by the LV ejection fraction (LVEF) and the wall motion severity index (WMSI [SD/chords]). A repeat angiography was available in 119 patients after 4.9 +/- 1.4 m. An improvement of WMSI > or =1 SD/chord was considered significant. Left ventricular function was normal in 42%, regional dysfunction with LVEF > or = 0.60 was observed in 16%, and regional dysfunction with LVEF < 0.60 in 42%. The former had a better collateral function than patients with LV dysfunction. In 39% of patients with LV dysfunction, a significant myocardial recovery was observed at follow-up. The collateral function was similar in patients with and without recovery. However, patients with recovery had a lower peripheral resistance as an indicator of a better preserved microvascular integrity. Recovery of impaired LV function after revascularization of a CTO is not directly related to the quality of collateral function, as collateral development does not appear to require the presence of viable myocardium. However, a preserved microvascular integrity may be of relevance for myocardial recovery.

Collateral function is impaired in aged F344 × BN rats with aortic pathology

Introduction: This study was performed to determine if hindlimb collateral function is impaired in a rat model which develops age-related vascular pathology similar to that observed in humans. Methods: Rats aged 6 (n = 6) and 24 (n = 6) months were studied. Under pentobarbital anesthesia, iliac artery blood flow was measured before and during occlusion of the femoral artery. The thoracic aorta, abdominal aorta, iliac arteries, and femoral arteries were harvested after perfusion fixation with paraformaldehyde and subsequently plastic embedded, sectioned, and stained. Results: Prior to occlusion, iliac flows were 3.0 ± 0.01 mL/min and 3.5 ± 0.02 mL/min respectively in 6 and 24 month old rats. After occlusion in the young rats, flow dropped initially by 0.8 ± 0.01 mL/min and then recovered by 0.7 ± 0.02 mL/min, essentially reaching pre-occlusion values. In 24 month old animals, flow decreased initially by 0.9 ± 0.01 mL/min but only recovered 0.4 ± 0.01 mL/min (p < 0.05). Intimal thickening was apparent only in the thoracic aorta of 24 month old animals. Conclusions: The increase in iliac artery blood flow after femoral artery occlusion reflects dilation of collateral vessels. The reduced compensation in older animals suggests that flow-dependent collateral dilation is reduced. This is consistent with studies which have demonstrated a progressive increase in endothelial dysfunction with aging. These observations together with the aortic pathology are consistent with the hypothesis that vascular aging not only promotes large vessel pathology, but also suppresses the capacity for compensation such as collateral dilation.

Regression of Collateral Function After Recanalization of Chronic Total Coronary Occlusions

Collaterals can maintain myocardial function or preserve viability in chronic total coronary occlusions (CTOs). It is unknown whether and to what extent collaterals regress after successful recanalization of a CTO. In 103 patients with successful recanalization of a CTO collateral function was assessed by intracoronary Doppler and pressure recordings before and after recanalization, and again after 5.0+/-1.3 months. Doppler (CFI) and pressure-derived collateral function indexes (CPI) and collateral (RColl) and peripheral resistance indexes (RP) were calculated. In 10 patients with reocclusion, all without myocardial infarction during follow-up, collateral function had reached a similar level as before the first recanalization. In the other 93 patients with or without restenosis, collateral function was attenuated during follow-up. CPI had decreased by 23% immediately after recanalization (P<0.001) and decreased further by another 23% at follow-up (P<0.001). The RColl increased immediately after recanalization by 82% (P<0.001) and by a further 273% at follow-up (P<0.001). In contrast, RP increased only by 22% after recanalization (P<0.001) and by an additional 12% at follow-up (P<0.05). The initial size of the collaterals but not the incidence of a restenosis influenced the collateral regression. Only 18% of patients at follow-up had collaterals with a CPI >0.30, presumably sufficient to prevent ischemia during acute occlusion. Collateral function regresses during long-term follow-up, especially in collaterals with a small diameter. In the majority of patients, collaterals are not readily recruitable in the case of acute occlusion. However, collaterals have the potential to recover in the case of chronic reocclusion.

Exercise-Induced Human Coronary Collateral Function: Quantitative Assessment during Acute Coronary Occlusions

In 50 patients undergoing percutaneous transluminal coronary angioplasty because of chronic angina pectoris, a collateral flow index (CFI) was determined at the start and the end of two 1-min coronary occlusions, randomly accompanied by a resting state or a 3-min dynamic handgrip exercise (DHE). CFI expressing collateral flow relative to normal antegrade flow was determined by simultaneous coronary occlusive pressure, mean aortic pressure and central venous pressure measurements. When comparing CFI without and with DHE at the start as well as at the end of balloon occlusions, a significant increase was observed with DHE (overall p < 0.0001); start: 0.18 ± 0.12 vs. 0.22 ± 0.13, respectively (p = 0.01); end of occlusion: 0.21 ± 0.14 vs. 0.25 ± 0.14, respectively (p = 0.007).

Determinants of target vessel failure in chronic total coronary occlusions after stent implantation: the influence of collateral function and coronary hemodynamics

Further medieval Arabic documents are referred to on the history of knowledge of seasonally reversing surface currents, semidiurnal tides and winds in the North Indian Ocean and also in the South Indian Ocean. A “theory” of tides based on the lunar cycle was described by Ibn Khordazbeh (846) and by Al Mokaddasi (985). Utilization of tidal currents in turning water-wheels and flour mills in Basea (Irak) in the 10th century was also noted by the second author.

Venous Drainage Patterns in a Case of Pseudotumor Cerebri Following Unilateral Radical Neck Dissection

We report the extracranial venous ultrasound findings in a case of pseudotumor cerebri (PTC) following unilateral radical neck dissection (rND). PTC is known to be a rare complication following bilateral rND, and is caused by venous outflow obstruction. Single cases of PTC have been reported after unilateral rND, and are thought to be due to resection of the dominant internal jugular vein (IJV) in the presence of a hypoplastic or aplastic contralateral transverse sinus. Our patient developed PTC despite prominent flow in the contralateral IJV as shown by venous ultrasound. No compensatory increase in flow in the vertebral veins was observed, as confirmed by digital subtraction angiography. We conclude that the physiological collateral function of the vertebral venous system and deep neck veins was insufficient and contributed to global venous outflow obstruction in our case of unilateral rND.

Incorporating Collateral Value Uncertainty in Loss Given Default Estimates and Loan‐to‐value Ratios

AbstractWe present a model of risky debt in which collateral value is correlated with the possibility of default. The model is then used to study the expected loss given default, primarily as a function of collateral. The results obtained could prove useful for estimating losses given default in many popular models of credit risk which assume them constant. We also examine the problem of determining sufficient collateral to secure a loan to a desired extent. In addition to bank practitioners, regulators might find our analysis useful in reviewing banks’ lending standards relative to current collateral values. In particular, the current proposals for The New (Basel) Capital Accord involve options for the use of banks’ own loss given default estimates which might benefit from the analysis in this paper.

Determinants of target vessel failure in chronic total coronary occlusions after stent implantation: The influence of collateral function and coronary hemodynamics

ObjectivesThe goal of this study was to assess the influence of collateral function, coronary hemodynamics, and the angiographic result on the risk of target vessel failure (TVF) after recanalization of a chronic total coronary occlusion (CTO). BackgroundCollaterals may have an adverse effect on TVF. MethodsIn 111 consecutive patients, a CTO (duration >2 weeks) was successfully recanalized with stent implantation. Collateral function was assessed by intracoronary Doppler flow velocity and pressure recordings distal to the occlusion. Baseline collateral function was determined before the first balloon inflation, and recruitable collateral function after stenting during a balloon reocclusion. Finally, the coronary flow velocity reserve (CFVR) and the fractional flow reserve (FFR) were measured. ResultsAngiographic follow-up after 5 ± 1.4 months in 106 patients showed a reocclusion in 17% and a restenosis in 36%. The major determinants of TVF were the stent length (p < 0.01) and number of implanted stents (p < 0.01). No difference was observed in baseline or recruitable collateral function between patients with and without TVF; 52% of patients had a CFVR ≥2.0, and only 18% a CFVR ≥2.5 after percutaneous transluminal coronary angioplasty, but neither cutoff-value predicted TVF. A low FFR discriminated patients with reocclusion (0.81 ± 0.07 vs. 0.86 ± 0.08, p < 0.05) but not with restenosis (0.87 ± 0.06). ConclusionsThis study showed that there is no relation between a well-developed collateral supply and the risk of TVF in recanalized CTOs. This was rather determined by the stented segment length. There was also no adverse effect of the frequently observed impaired CFVR on TVF, whereas a low FFR was associated with a higher risk of reocclusion.

Absent Collateral Function of the Circle of Willis as Risk Factor for Ischemic Stroke

Background: Autopsy studies show a higher prevalence of circle of Willis anomalies in brains with signs of ischemic infarction. Our goal was to examine the collateral function of the circle of Willis in ischemic stroke patients and to assess in a case-control study if a collateral deficient circle of Willis is a risk factor for ischemic stroke in patients with severe internal carotid artery (ICA) occlusive disease. Methods: Our case-control study included 109 patients with an acute ischemic stroke in the anterior circulation and 113 patients with peripheral arterial disease and no known history of cerebral ischemia. The collateral function of the anterior and posterior communicating arteries of the circle of Willis was assessed by means of transcranial color-coded duplex ultrasonography (TCCD) and carotid compression tests. Results: TCCD was successfully performed in 75 case patients (mean age 64 years, range 41–91 years) and in 100 control patients (mean age 61 years, range 35–89 years). In 26 cases and 19 controls, a ≧70% stenosis or occlusion of the ICA was found. A nonfunctional anterior collateral pathway in the circle of Willis was found in 33% of the cases and in 6% of the controls (p < 0.001). The posterior collateral pathway was nonfunctional in 57% of the cases and in 43% of the controls (p = 0.02). In patients with severe ICA occlusive disease, the odds ratios of a nonfunctional anterior and a nonfunctional posterior collateral pathway were 7.33 (95% confidence interval, CI, = 1.19–76.52) and 3.00 (95% CI = 0.77–12.04), respectively. Conclusions: Patients who suffer ischemic stroke in the anterior circulation have a higher incidence of collateral deficient circles of Willis than those with atherosclerotic vascular disease without ischemic cerebrovascular disease. The presence of a nonfunctional anterior collateral pathway in the circle of Willis in patients with severe ICA occlusive disease is strongly associated with ischemic stroke.

Impaired acute collateral recruitment as a possible mechanism for increased cardiac adverse events in patients with diabetes mellitus.

The mortality of coronary artery disease is increased in diabetic patients. An impaired collateral function is considered a possible explanation. This study should assess the influence of diabetes on collaterals by direct invasive assessment of collateral function. In 90 consecutive patients with a chronic coronary occlusion (TCO) of >2 weeks duration a recanalization was done. Thirty patients with diabetes (33%) were compared with 60 (67%) without diabetes. Blood flow velocity and pressure were measured distal to the occlusion by intracoronary Doppler and pressure wires before PTCA, and again after PTCA during a final balloon reocclusion to assess acute recruitment of collaterals. Resistance indexes for collaterals (R(Coll)) and peripheral microcirculation (R(P)) were calculated. The R(Coll)(diabetics: 8.1+/-6.8 vs nondiabetics: 8.7+/-6.7 mmHg cm(-1)s(-1); p=0.68) and R(P)(5.6+/-4.2 vs 6.6+/-3.8 mmHg cm(-1)s(-1); p=0.30) were similar in diabetic and nondiabetic patients before recanalization. During balloon reocclusion both R(Coll)and R(P)increased. This increase was significantly more pronounced in diabetic than in nondiabetic patients in TCOs <3 months duration. In TCOs of longer duration (> or =3 months) these differences were no longer detectable between both patient groups. Diabetic patients with TCOs have similarly developed collaterals as nondiabetic patients. However, in TCOs <3 months duration the acute recruitment of collaterals in case of reocclusion is impaired. This could explain some of the higher complication rate and mortality after coronary interventions in diabetic patients.

Transection of intrinsic polysynaptic pathways reduces N-methyl- d-aspartate neurotoxicity in hippocampal slice cultures

Hippocampal CA1 neurons have been shown to be highly susceptible to excitotoxicity produced by various forms of insult. CA1 neurotoxicity is partly dependent on over activity of N-methyl- d-aspartate (NMDA) receptors. It is unclear, however, if sensitivity of this region to excitotoxicity is related to inherent properties of CA1 neurons and/or network activation of polysynaptic pathways. The present studies examined the role of mossy fiber and Schaffer collateral function in promoting NMDA-induced neurodegeneration. Organotypic hippocampal cultures were subjected to transection of mossy fibers, Schaffer collaterals, or CA1 efferent fibers and then exposed to NMDA (20 μM) for 1 h. Hippocampal damage was assessed 24 h later via fluorescent microscopy. NMDA exposure produced significant excitotoxicity in all regions (160–500% of control), particularly in the CA1. In each region, toxicity was reduced by co-exposure to NMDA with MK-801 (20 μM), to near-control levels. Surgical transection of mossy fibers and Schaffer collaterals significantly reduced NMDA-induced neurotoxicity in the CA1 (∼20%), and to a lesser extent, the CA3 and dentate regions. Conversely, transection of CA1 efferent fibers did not reduce the neurotoxicity in these regions. These data indicate that CA1 neurotoxicity caused by excitotoxic insult depends, in part, on ‘network activation’ of intrinsic polysynaptic pathways.

Coronary collaterals: an important and underexposed aspect of coronary artery disease.

Important risk factors for cardiovascular disease (CVD) have been identified, but they fail to explain why some patients with atherosclerosis become symptomatic and have recurrent symptomatic disease, and others do not. Apart from the extent of coronary atherosclerosis (among other factors), the sensitivity of organs to episodes of ischemia is probably of importance. An organ may be less sensitive to episodes of ischemia if supplied with sufficient blood flow by well-developed collateral vessels. Unfortunately, some organs or even some individuals do not appear to have well-developed collateral vessels, if developed at all. At present, it is not clear why there are differences between individuals in their capability of developing a sufficient collateral circulation. The potential of individuals to develop coronary collateral circulation has so far been largely neglected but may play a major role in determining myocardial vulnerability. In the present article, we propose why coronary collaterals are important, and why this individual potential to develop collaterals should be considered an additional indicator of cardiac vulnerability. Also, we review determinants that play a role in collateral coronary blood supply. Coronary collaterals, or “natural bypasses,” are anastomotic connections without an intervening capillary bed between portions of the same coronary artery and between different coronary arteries (Figure 1).1 Collateral circulation potentially offers an important alternative source of blood supply when the original vessel fails to provide sufficient blood.2 Timely enlargement of collaterals may even avoid transmural myocardial infarction (MI) and death in symptomatic patients.3 As early as in 1956, Baroldi et al4 demonstrated the presence at birth of mostly corkscrew-shaped collaterals in normal human hearts, with a lumen diameter of 20 to 350 μm and lengths ranging from 1 or 2 cm to 4 or 5 cm. In hearts with typical findings of coronary disease at autopsy, …

P1184 Growth factor generation in the collateral system of chronically occluded coronary arteries and its relation to invasively determined collateral function

P1184 Growth factor generation in the collateral system of chronically occluded coronary arteries and its relation to invasively determined collateral function