Biomedical subjects
F V Aguirre
Publications and source records attributed to F V Aguirre.
Characterization of intra-arterial flow velocity within left coronary to pulmonary artery fistula.
The physiology of a coronary to pulmonary artery fistula has not been well characterized. This case report demonstrates the flow velocity pattern of a coronary fistula to the pulmonary artery which supports the hypothesized physiology that flow is predominantly continuous without a phasic pattern. The flow velocity within a coronary fistula has not been previously demonstrated.
Role of coronary artery lumen enlargement in improving coronary blood flow after balloon angioplasty and stenting: a combined intravascular ultrasound Doppler flow and imaging study.
OBJECTIVES: This study sought to examine the mechanism of increasing coronary flow reserve after balloon angioplasty and stenting. BACKGROUND: Coronary vasodilatory reserve (CVR) does not improve after percutaneous transluminal coronary angioplasty in > or = 50% of patients, postulated to be due to impaired microvascular circulation or inadequate lumen expansion despite adequate angiographic results. METHODS: To demonstrate the role of coronary lumen expansion, serial coronary flow velocity (0.014-in. Doppler guide wire) was measured in 42 patients before and after balloon angioplasty and again after stent placement. A subset (n = 17) also underwent intravascular ultrasound (IVUS) imaging of the target sites after angioplasty and stenting. CVR (velocity) was computed as the ratio of adenosine-induced maximal hyperemic to basal average peak velocity. RESULTS: The percent diameter stenosis decreased from (mean +/- SD) 84 +/- 13% to 37 +/- 18% after angioplasty and to 8 +/- 8% after stenting (both p < 0.05). CVR was minimally changed from 1.70 +/- 0.79 at baseline to 1.89 +/- 0.56 (p = NS) after angioplasty but increased to 2.49 +/- 0.68 after stent placement (p < 0.01 vs. before and after angioplasty). IVUS lumen cross-sectional area was significantly larger after stenting than after angioplasty (8.39 +/- 2.09 vs. 5.10 +/- 2.03 mm2, p < 0.05). Anatomic variables were related to increasing coronary flow velocity reserve (CVR vs. IVUS lumen area: r = 0.47, p < 0.005; CVR vs. quantitative coronary angiographic percent area stenosis: r = 0.58, p < 0.0001). CONCLUSIONS: In most cases, increases in CVR were associated with increases in coronary lumen cross-sectional area. These data suggest that impaired CVR after angioplasty is often related to the degree of residual narrowing, which at times may not be appreciated by angiography. A physiologically complemented approach to balloon angioplasty may improve procedural outcome.
Evidence for prevention of death and myocardial infarction with platelet membrane glycoprotein IIb/IIIa receptor blockade by abciximab (c7E3 Fab) among patients with unstable angina undergoing percutaneous coronary revascularization. EPIC Investigators. Evaluation of 7E3 in Preventing Ischemic Complications.
OBJECTIVES: We sought to evaluate whether patients with unstable angina undergoing coronary intervention derive particular clinical benefit from potent platelet inhibition. BACKGROUND: Plaque rupture and platelet aggregation are pathogenetic processes common to unstable angina and ischemic complications of percutaneous coronary intervention. METHODS: Of the 2,099 patients undergoing a coronary intervention in the Evaluation of 7E3 in Preventing Ischemic Complications (EPIC) trial, 489 were enrolled with the diagnosis of unstable angina and randomized to receive placebo, an abciximab (c7E3) bolus immediately before the intervention or an abciximab bolus followed by a 12-h infusion. The primary end point was a composite of death, myocardial infarction (MI) or urgent repeat revascularization within 30 days of randomization. The occurrence of death, MI or any revascularization within 6 months was also assessed. RESULTS: Compared with placebo, the bolus and infusion of abciximab resulted in a 62% reduction in the rate of the primary end point (12.8% vs. 4.8%, p = 0.012) among patients with unstable angina, due primarily to a reduction in the incidences of death (3.2% vs. 1.2%, p = 0.164) and MI (9% vs. 1.8%, p = 0.004). By 6 months, cumulative death and MI were further reduced by abciximab (6.6% vs. 1.8%, p = 0.018 and 11.1% vs. 2.4%, p = 0.002, respectively). The magnitude of the risk reduction with abciximab was greater among the patients with unstable angina than among other patients in the EPIC trial without unstable angina for the end points of death (interaction: p = 0.008 at 30 days, p = 0.002 at 6 months) and MI (interaction: p = 0.004 at 30 days, p = 0.003 at 6 months). CONCLUSIONS: The syndrome of unstable angina identifies patients who will experience particularly marked reductions in the risk of death and MI with abciximab during coronary intervention.
Variations in normal coronary vasodilatory reserve stratified by artery, gender, heart transplantation and coronary artery disease.
OBJECTIVES: The purpose of the study was to assess the spectrum of coronary vasodilatory reserve values in patients with angiographically normal arteries who had atypical chest pain syndromes or remote coronary artery disease or were heart transplant recipients. BACKGROUND: The measurement of post-stenotic coronary vasodilatory reserve, now possible in a large number of patients in the cardiac catheterization laboratory, is increasingly used for decision making. Controversy exists regarding the range of normal values obtained in angiographically normal coronary arteries in patients with different clinical presentations. METHODS: Quantitative coronary arteriography was performed in 214 patients classified into three groups: 85 patients with chest pain syndromes and angiographically normal arteries (group 1); 21 patients with one normal vessel and at least one vessel with > 50% diameter lumen narrowing (group 2); and 108 heart transplant recipients (group 3). Coronary vasodilatory reserve (the ratio of maximal to basal average coronary flow velocity) was measured in 416 arteries using a 0.018-in. (0.04 cm) Doppler-tipped angioplasty guide wire. Intracoronary adenosine (8 to 18 micrograms) was used to produce maximal hyperemia. RESULTS: Coronary vasodilatory reserve was higher in angiographically normal arteries in patients with chest pain syndromes (group 1:2.80 +/- 0.6 [group mean +/- SD]) than in normal vessels in patients with remote coronary artery disease (group 2: 2.5 +/- 0.95, p = 0.04); both values were significantly higher than those in the post-stenotic segment of the diseased artery (1.8 +/- 0.6, p < 0.007). Coronary vasodilatory reserve in transplant recipients (group 3) was higher than that in the other groups (3.1 +/- 0.9, p < 0.05 vs. groups 1 and 2) as a group and for individual arteries. When stratified by vessel, coronary vasodilatory reserve was similar among the left anterior descending, left circumflex and right coronary arteries. There were no differences between coronary vasodilatory reserve values on the basis of gender for patients with coronary artery disease and transplant recipients. In group 1 (chest pain), there was a trend toward higher coronary vasodilatory reserve in men than in women (2.9 +/- 0.6 vs 2.7 +/- 0.6, p = 0.07). CONCLUSIONS: These findings identify a normal reference range for studies assessing the coronary circulation and post-stenotic coronary vasodilatory reserve in patients with and without coronary artery disease encountered in the cardiac catheterization laboratory.
Determination of angiographic (TIMI grade) blood flow by intracoronary Doppler flow velocity during acute myocardial infarction.
BACKGROUND: This study compared angiographically graded coronary blood flow with intracoronary Doppler flow velocity in patients during percutaneous transluminal coronary angioplasty (PTCA) for acute myocardial infarction. Different TIMI angiographic flow grades (flow grades based on results of the Thrombolysis in Myocardial Infarction trial) have been associated with different clinical results after reperfusion for acute myocardial infarction. However, intracoronary blood flow velocity has not been compared with the angiographic method of determining flow grade in patients. METHODS AND RESULTS: Coronary flow velocity (measured by use of a Doppler guidewire) during primary or rescue PTCA in 41 acute myocardial infarction patients was compared with TIMI grade and cineframes-to-opacification count. Before PTCA, 34 patients had TIMI grade 0 or 1, 5 had TIMI grade 2, and 2 had TIMI grade 3 flow in the infarct artery. Flow velocity was similar among patients with TIMI grades 0, 1, or 2 but was lower than in those with TIMI grade 3 flow (9.4 +/- 5.4 versus 16.0 +/- 5.4 cm/s for TIMI grades < or = 2 versus TIMI grade 3, respectively; P < .05). After PTCA, 1 patient had TIMI grade 1, 5 had TIMI 2, and 35 had TIMI 3 flow. Poststenotic flow velocity increased from 6.6 +/- 6.1 to 20.0 +/- 11.1 cm/s (P < .01). TIMI grade 3 flow increased to 21.8 +/- 10.9 cm/s (P < .05 versus before PTCA). Although post-PTCA flow velocity correlated with angiographic cineframes-to-opacification count (r = .45; P < .02) for TIMI grade 3, there was a large overlap with TIMI grades < or = 2 that had low flow velocity (< 20 cm/s). Nine of 11 clinical events (unstable angina and coronary artery bypass graft surgery) occurred in patients with low coronary flow velocity. CONCLUSIONS: Determination of flow velocity after reperfusion may enhance patient characterization and provide the physiological rationale for clinical variations after reperfusion therapy.
Correlation of poststenotic hyperemic coronary flow velocity and pressure with abnormal stress myocardial perfusion imaging in coronary artery disease.
The functional significance of coronary stenoses is frequently determined by adjunctive noninvasive myocardial perfusion imaging. Poststenotic coronary flow velocity and pressure can be measured directly during routine cardiac catheterization. The aim of this study was to correlate poststenotic (distal) flow velocity and pressure with stress perfusion imaging in patients. Quantitative angiography, basal and hyperemic transstenotic coronary flow velocities, and pressure gradients were measured in 50 patients within 1 week of exercise (n = 29) or of pharmacologic (n = 21) stress perfusion imaging. Twenty-two of 25 patients (88%) with reversible perfusion abnormalities had diminished distal coronary flow velocity reserves (CFVR) of < or = 2.0 x baseline, whereas 22 of 25 (88%) with normal perfusion imaging studies had a normal distal CFVR of > 2.0 (p = 0.000 1). Thirteen of 25 patients (52%) with reversible perfusion abnormalities had transstenotic gradients > or = 20 mm Hg, whereas 20 of 25 (80%) with normal perfusion studies had gradients <20 mm Hg (p = 0.01). Quantitative angiography did not differentiate patients with normal versus abnormal myocardial perfusion imaging. Distal CFVR was correlated more significantly with myocardial perfusion imaging results (kappa = 0.76) than with pressure gradients (kappa = 0.32). Exercise and pharmacologic stress myocardial perfusion imaging abnormalities reflect diminished post-stenotic coronary flow to a greater degree than transstenotic pressure gradients.
Lesion-directed administration of alteplase with intracoronary heparin in patients with unstable angina and coronary thrombus undergoing angioplasty.
Percutaneous coronary revascularization in patients with unstable angina and coronary thrombus carries a high complication rate. A new strategy to reduce thrombus burden before revascularization was tested in a multicenter prospective trial. Patients with unstable angina and coronary thrombus (n = 45) received alteplase through an infusion catheter at the proximal aspect of the target lesion and concomitant intracoronary heparin via a standard guiding catheter. Angiography was performed before and alter lesion-directed therapy and post-intervention. Systemic fibrinogen depletion and thrombin activation were not observed, while fibrinolysis was evident for > or = 4 hr after treatment. Target lesion stenosis did not change significantly after lesion-directed therapy, but thrombus score was reduced, particularly among patients who had large thrombi (mean 2.2 vs. 1.6, P = 0.02). Revascularization was successful in 89% of patients. Median final stenosis was 30% and mean final thrombus score was 0.4. Complications included recurrent ischemia (11%), MI (7%), abrupt closure (7%), severe bleeding (4%), and repeat emergency angioplasty (2%). Patients with overt thrombus appeared to derive the most angiographic benefit from lesion-directed alteplase plus intracoronary heparin. Later revascularization was highly successful. This strategy may be a useful adjunct to percutaneous revascularization for patients with unstable angina and frank intracoronary thrombus.
Differential characterization of human coronary collateral blood flow velocity.
The functional importance and protective nature of the coronary collateral circulation has been well established. There are few data, however, regarding the phasic nature and absolute velocities of collateral flow in patients. The aim of this study was to characterize and quantify ipsilateral coronary collateral blood flow velocity in patients during coronary angioplasty. Coronary collateral flow velocity was measured in 49 patients during coronary angioplasty. Angiographic collateral filling was categorized by the Rentrop grading scale (0 to 3) and by anatomic pathway (epicardial, intramyocardial, or unknown [acutely recruited]). Collateral blood flow velocity was measured with a Doppler-tipped guide wire placed distal to the balloon occlusion in the collateralized vessel. Collateral flow velocity was characterized as predominantly systolic or diastolic, and phasic flow patterns were defined as biphasic (both systolic and diastolic), monophasic (only systolic or diastolic), or bidirectional (antegrade and retrograde velocity). Twenty-three (47%) patients had biphasic flow; 17 (35%) patients had monophasic flow; and 9 (18%) patients had bidirectional flow. Thirty-six (73%) of 49 patients had predominantly systolic flow signals. Epicardial collateral pathways had the highest total flow velocity integral, at 15.0 +/- 7.0 (vs intramyocardial [8.4 +/- 5.7] and acutely recruitable [5.4 +/- 2.1]; p < 0.05). There were no differences in flow velocity integrals among the Rentrop angiographic grades of collateral filling. These data establish three patterns of coronary collateral blood flow and demonstrate that the majority of collateral flow in the ipsllateral receiving vessel occurs during systole. The measurement of coronary collateral flow velocity provides a unique means to study the effects of pharmacologic or mechanical interventions on human collateral blood flow.
Influence of percutaneous transluminal coronary rotational atherectomy with adjunctive percutaneous transluminal coronary angioplasty on coronary blood flow.
The purpose of this study was to examine the influence of sequential percutaneous transluminal coronary rotational atherectomy (PTCRA) and coronary angioplasty on coronary blood flow reserve in patients. Rotational coronary atherectomy restores lumen patency by partially ablating fibrocalcific plaque, releasing microparticulate debris into the distal coronary circulation. Adjunctive balloon angioplasty is usually performed to optimize the angiographic luminal dimensions. Serial alterations in coronary physiology have not been reported. Fourteen lesions in 13 patients were treated by sequential rotational atherectomy followed by adjunctive balloon angioplasty. Poststenotic baseline coronary blood flow velocity was measured by using a Doppler flow wire (FloWire, Cardiometrics, Inc., Mountain View, Calif.), and coronary blood flow was calculated by using the distal vessel cross-sectional area obtained by quantitative coronary angiography. Data were acquired at baseline and during hyperemia (12 to 18 microg of intracoronary adenosine), before and after PTCRA, and again after balloon angioplasty. The mean stenosis decreased from 76 percent +/- 12 percent at baseline to 21 percent +/- 11 percent at the completion of the procedure (p<0.01). The minimal luminal diameter (by quantitative coronary angiography) was 0.7 +/- 0.4 mm at baseline, increased to 1.9 +/- 0.4 mm after rotational atherectomy (p<0.01), and increased to 2.4 +/- 0.5 mm after balloon angioplasty (p<0.01 versus baseline and PTCRA). Distal (poststenotic) coronary blood flow at baseline was 47 +/- 23 ml/min and 57 +/- 38 ml/min during hyperemia. After PTCRA, coronary blood flow increased to 104 +/- 59 ml/min and to 132 +/- 73 ml/min with hyperemia. After adjunctive angioplasty, coronary blood flow was 84 +/- 40 ml/min (p=not significant [NS] vs PTCRA) and increased to 143 +/- 81 ml/min with hyperemia (p=NS vs PTCRA). The poststenotic coronary flow reserve increased from an initial value of 1.1 +/- 0.2 ml/min to 1.3 +/- 0.3 ml/min after PTCRA (p=NS vs baseline) and to 1.6 +/- 0.3 ml/min after adjunctive balloon angioplasty (p<0.01 vs p=NS vs PTCRA). PTCRA significantly increased resting coronary blood flow. Adjunctive balloon angioplasty did not significantly augment resting or hyperemic coronary blood flow more than that achieved by rotational atherectomy alone. These data demonstrate that PTCRA alone improves baseline coronary blood flow with minimal additional physiologic change after adjunctive balloon angioplasty.
Bleeding complications with the chimeric antibody to platelet glycoprotein IIb/IIIa integrin in patients undergoing percutaneous coronary intervention. EPIC Investigators.
BACKGROUND: The potential for novel antiplatelet and antithrombin agents to contribute to periprocedural bleeding complications of percutaneous coronary revascularization is poorly defined. In the Evaluation of c7E3 Fab in Preventing Ischemic Complications of High-Risk Angioplasty (EPIC) trial, the periprocedural use of aspirin, heparin, and a chimeric antibody to the platelet glycoprotein IIb/IIIa integrin c7E3 Fab in 2099 patients significantly reduced postprocedural ischemic complications and 6-month clinical restenosis but was associated with increased procedural bleeding complications. We review these complications and describe clinical and procedural variables associated with increased bleeding complications in the EPIC trial. METHODS AND RESULTS: Patients with high-risk clinical or lesion morphological characteristics were randomized to receive placebo bolus plus placebo infusion, c7E3 Fab bolus plus placebo infusion, or c7E3 Fab bolus plus c7E3 Fab infusion. Patients received periprocedural aspirin and intravenous heparin continued for a minimum of 12 hours after the procedure. Outcomes reflecting bleeding complications were measured: transfusions, decreased hemoglobin, and an index including both parameters. Major bleeding complications unrelated to bypass surgery occurred in 3.3%, 8.6%, and 10.6%, and blood product transfusions were used in 7.5%, 14.0%, and 16.8% of patients treated with placebo, bolus c7E3 Fab, and bolus plus infusion c7E3 Fab, respectively (both P < .001). Most major bleeding complications occurred at the femoral access site, regardless of treatment. Intracranial hemorrhage (0.3%) and death (0.09%) attributable to major bleeding complications were rare. Multivariable regression analyses identified several variables significantly and independently related to major bleeding complications or greater blood loss, including greater age, female sex, lower weight, c7E3 Fab therapy, and duration and complexity of the index procedure. Major bleeding complications and blood loss in patients receiving bolus plus infusion were not significantly greater than in those receiving bolus alone (P = .38 and P = .14, respectively). CONCLUSIONS: Bleeding complications unrelated to bypass surgery were two to three times more frequent in patients receiving c7E3 Fab than in those receiving placebo, but most were transient and well tolerated. Risk-factor analysis and modification of concomitant antithrombotic and antiplatelet treatment strategies may aid in reducing bleeding complications and enhancing clinical benefit in patients receiving c7E3 Fab during percutaneous coronary revascularization.
Early and 1-year clinical outcome of patients' evolving non-Q-wave versus Q-wave myocardial infarction after thrombolysis. Results from The TIMI II Study.
BACKGROUND: There are few data comparing clinical outcome and potential indications for routine post-myocardial infarction cardiac catheterization and revascularization of patients who sustain a non-Q-wave versus Q-wave infarct after thrombolytic therapy. METHODS AND RESULTS: A secondary analysis of 2634 patients enrolled in the TIMI II trial with a first myocardial infarction was performed to determine 6-week and 1-year cardiac event rates and identify clinical and angiographic differences between the 1867 patients (70.9%) who evolved a Q-wave infarct and the 767 patients (29.1%) who sustained a non-Q-wave infarct after treatment with intravenous thrombolytic therapy. Male sex (85.3% versus 75.6%; P < .001) and anterior wall infarcts (53.8% versus 43.7%; P < .001) were more frequent in the Q-wave versus the non-Q-wave group. During recombinant tissue-type plasminogen activator (rTPA) infusion, a greater percentage of non-Q-wave patients (37.3% versus 23.5%; P = .001) had normalization of initial ST-segment elevation. Infarct-related artery patency (TIMI flow grade 2 or 3) (P = .02), complete infarct-related artery reperfusion (TIMI 3 flow grade) (P < .001), and the percentage of patients with a predischarge resting left ventricular ejection fraction > 55% (P < .001) were greater in the non-Q-wave group. New congestive heart failure during hospitalization developed more frequently in Q-wave patients (18.9% versus 11.6%; P < .001). After 42 days, the occurrences of reinfarction (P = .76), death (P = .76), and combined death or reinfarction (P = .43) were similar in patients assigned to the invasive or conservative postlytic management strategy, regardless of infarct type. One-year mortality was 3.4% versus 4.4% for non-Q-wave versus Q-wave infarct type, respectively (P = .25). CONCLUSIONS: Angiographic and clinical differences were observed between patients who present with initial ST-segment elevation and evolve early non-Q-wave versus Q-wave myocardial infarcts after treatment with rTPA, heparin, and aspirin. Early mortality and adverse clinical cardiac events in these patients are not significantly different after a conservative compared with an invasive treatment strategy, regardless of whether the infarct type is non-Q wave or Q wave.
Clinical and operative characteristics of patients randomized to coronary artery bypass surgery in the Bypass Angioplasty Revascularization Investigation (BARI).
The surgical cohort of the Bypass Angioplasty Revascularization Investigation (BARI) is the largest group of patients with multivessel coronary artery disease randomly assigned to surgical treatment. This report presents baseline and operative characteristics of the cohort and describes some aspects of the variability in surgical practice among the 14 primary clinical centers and 4 co-investigational sites participating in BARI. Preoperative clinical and angiographic data and intraoperative variables were reviewed in 892 patients who were randomly assigned to coronary artery bypass grafting (CABG) and underwent operation. Associations between patient/lesion variables and operative characteristics are described. Of patients assigned to CABG, 87% underwent an operation within 2 weeks of randomization, as recommended in the protocol. Mean age of the 892 patients was 61 years, and mean age of the 235 women was greater than that of men (64 years vs 60 years); 64% of the surgical patients were classified as having unstable angina during the 6 weeks prior to randomization. Coronary angiography demonstrated 3-vessel disease (50% diameter narrowing by caliper measurement) in 41% of patients, and disease of the left anterior descending coronary artery was present in 87% of patients. A mean of 3.1 coronary arteries per patient were bypassed, and 82% of patients received 1 (70%) or 2 (12%) internal thoracic artery grafts. Prevalence of internal thoracic grafts was lower in elderly patients (74% of patients > or = 70 years), in women (72% vs 85% in men; p < 0.01), and in black participants (65%).(ABSTRACT TRUNCATED AT 250 WORDS)
Effect of platelet glycoprotein IIb/IIIa integrin blockade on activated clotting time during percutaneous transluminal coronary angioplasty or directional atherectomy (the EPIC trial). Evaluation of c7E3 Fab in the Prevention of Ischemic Complications trial.
The activated clotting time (ACT) has been used during percutaneous transluminal coronary angioplasty (PTCA) to monitor the extent of thrombin inhibition and anti-coagulation from heparin in an attempt to minimize untoward thrombotic events and hemorrhagic complications. With the introduction of potent platelet inhibitors, such as the chimeric monoclonal antibody c7E3, to interventional cardiology, the utility of measuring and regulating procedural ACT has not been examined. To investigate the possible influence of platelet IIb/IIIa antagonism on procedural ACT, we reviewed data from the Evaluation of c7E3 Fab in the Prevention of Ischemic Complications (EPIC) trial. In the EPIC trial, 2,099 patients undergoing PTCA with a high risk of abrupt vessel closure were randomized to receive placebo (n = 696) or the IIb/IIIa platelet receptor antagonist c7E3 Fab (n = 1,403). Despite receiving less procedural heparin, and fewer patients receiving very high heparin doses (> 14,000 U) than the placebo group, those receiving c7E3 had a higher mean (401 vs 367 seconds, p < 0.001) ACT when corrected for body weight. The ACT is increased approximately 35 seconds by the platelet IIb/IIIa receptor antagonist c7E3 Fab. This has important implications for dosing conjunctive heparin therapy and performing PTCA or directional coronary atherectomy in the setting of IIb/IIIa-directed therapy.
Comparison of quantitative angiographically derived and measured translesion pressure and flow velocity in coronary artery disease.
Although quantitative coronary angiography (QCA) has been used to determine lesion severity, angiographically derived parameters of translesional physiology have not been compared with those directly measured in the same patients. Thus, the aim of this study was to correlate QCA-derived translesional pressure and flow data with directly measured data in patients. QCA (DCI-ACA program), translesional pressure gradient (2.2Fr fluid-filled tracking catheter), and intracoronary Doppler flow velocity (0.018-inch FloWire) measurements were simultaneously performed in 28 arteries (25 patients). Mean diameter stenosis was 51 +/- 2.3% (range 29 to 73). No patient had left ventricular hypertrophy or valvular heart disease. The arteries studied were left anterior descending in 14, circumflex in 8, and right coronary in 6 patients. Stenotic flow reserve and baseline and maximal gradients were calculated by the DCI program. Coronary flow reserve and baseline and maximal hyperemic gradients were also directly measured distal to the stenosis after administration of intracoronary adenosine (12 to 18 micrograms). QCA-derived pressure gradients did not correlate with the measured gradients at baseline (r2 = 0.005; p = 0.73) or at maximal hyperemia (r2 = 0.1; p = 0.13). No correlation was found between the QCA-predicted flow reserve and the coronary flow reserve measured distal to the stenosis (r2 = 0.02; p = 0.46). Furthermore, stenotic flow reserve and measured gradient were not significantly correlated (r2 = 0.1; p = 0.16). In this range of stenoses of intermediate severity, there was no correlation between the measured pressure gradient or coronary flow reserve and lesion diameter or cross-sectional area by QCA.(ABSTRACT TRUNCATED AT 400 WORDS)
Interventional physiology. Part XIII: Role of large pectoralis branch artery in flow through a patent left internal mammary artery conduit.
Explore the source record for details and available documents.
Dynamic systolic coronary flow reversal and hyperemia in left anterior descending coronary blood flow velocity during Valsalva maneuver in a patient with hypertrophic cardiomyopathy.
Explore the source record for details and available documents.
Collateral flow velocity alterations in the supply and receiving coronary arteries during angioplasty for total coronary occlusion.
The unique observations of contralateral and ipsilateral coronary artery collateral supply before and after angioplasty suggest highly responsive conduits to hemodynamic conditions. The study of collateral supply system is not only significant for our current understanding of the dynamic behavior of the collateral circulation, but may also have important clinical implications for the treatment of patients with a chronic coronary occlusion.