Intracoronary Doppler Research Articles

Value of coronary stenotic flow velocity acceleration on the prediction of long-term improvement in functional status after angioplasty

Background The coronary flow velocity acceleration at the stenotic site (SVA), defined as a ≥50% increase in resting stenotic velocity when compared with the reference segment, has been shown to be highly sensitive and specific for the diagnosis of a hemodynamically significant stenosis. In this study, we describe the value of postprocedural SVA for the prediction of a lack of improvement in functional activity at long-term follow-up balloon angioplasty (BA). Methods We investigated the improvement in functional activity in patients undergoing single native vessel angioplasty and intracoronary Doppler (before BA, after BA, and again at 6-month follow-up) as part of the Doppler Endpoints Balloon Angioplasty Trial Europe (DEBATE) I trial. Lack of improvement was defined as no change in Duke Activity Status Index (DASI) at 6-month follow-up, whereas SVA was defined as ≥50% elevation in resting velocity at the treated area compared with the distal measurement. Results SVA was found more frequently in patients without improvement in DASI (45% vs 31%, P =.03). Similar percent diameter stenosis and coronary flow velocity reserve were observed in patients with and those without improvement in DASI at follow-up. By multivariate regression analysis, the presence of SVA (P =.029; odds ratio, 1.97; 95% confidence interval, 1.07 to 3.63) and an elevated DASI at baseline (P <.001; odds ratio, 1.05; 95% confidence interval, 1.03 to 1.07) were associated with a lack of improvement at follow-up. Conclusions The detection of SVA was associated with failure of improvement in functional activity at follow-up after coronary intervention. (Am Heart J 2001;142:81-6.)

Assessment of flow velocity reserve by transthoracic Doppler echocardiography and venous adenosine infusion before and after left anterior descending coronary artery stenting

OBJECTIVESWe sought to evaluate whether coronary flow velocity reserve (CFR) (the ratio between hyperemic and baseline peak flow velocity), as measured by transthoracic Doppler echocardiography during adenosine infusion, allows detection of flow changes in the left anterior descending coronary artery (LAD) before and after stenting.BACKGROUNDThe immediate post-stenting evaluation of CFR by intracoronary Doppler has shown mixed results, due to reactive hyperemia and microvascular stunning. Noninvasive coronary Doppler echocardiography may be a more reliable measure than intracoronary Doppler.METHODSTransthoracic Doppler echocardiography during 90-s venous adenosine infusion (140 μg/kg body weight per min) was used to measure CFR of the LAD in 45 patients before and 3.7 ± 2 days after successful stenting, as well as in 25 subjects with an angiographically normal LAD (control group).RESULTSAdequate Doppler spectra were obtained in 96% of the patients. Pre-stent CFR was significantly lower in patients than in control subjects (diastolic CFR: 1.45 ± 0.5 vs. 2.72 ± 0.71, p < 0.01; systolic CFR: 1.61 ± 1.02 vs. 2.41 ± 0.68, p < 0.01) and increased toward the normal range after stenting (diastolic CFR: 2.58 ± 0.7 vs. 2.72 ± 0.75, p = NS; systolic CFR: 2.43 ± 1.01 vs. 2.41 ± 0.52, p = NS). Diastolic CFR was often damped, suggesting coronary steal in patients with ≥90% versus <90% LAD stenosis (0.86 ± 0.23 vs. 1.69 ± 0.43, p < 0.01). Coronary stenting normalized diastolic CFR in these two groups (2.45 ± 0.77 and 2.64 ± 0.69, respectively, p = NS), even though impaired diastolic CFR persisted in three of four patients with ≥90% stenosis. Stenosis of the LAD was better discriminated by diastolic (F = 49.30) than systolic (F = 12.20) CFR (both p < 0.01).CONCLUSIONSCoronary flow reserve, as measured by transthoracic Doppler echocardiography, is impaired in LAD disease; it may identify patients with ≥90% stenosis; and it normalizes early after stenting, even in patients with ≥90% stenosis.

Randomized comparison of elective stent implantation and coronary balloon angioplasty guided by online quantitative coronary angiography and intracoronary doppler

Randomized comparison of elective stent implantation and coronary balloon angioplasty guided by online quantitative coronary angiography and intracoronary doppler

Impairment of coronary microvascular dilation in response to cold pressor--induced sympathetic stimulation in type 2 diabetic patients with abnormal stress thallium imaging.

Coronary microcirculation dysfunction may be associated with myocardial perfusion defects on thallium imaging in diabetic patients without coronary artery stenosis. Microvascular coronary adaptation to increased myocardial oxygen demand in response to sympathetic stimulation evoked by the cold pressor test was examined in 22 type 2 diabetic patients with thallium imaging defects and in 15 control subjects. Both the diabetic patients and control subjects had angiographically normal coronary arteries and no other risk factors. Despite a similar increase in the rate-pressure product in the two groups (22.6 +/- 12.4% in diabetic patients and 31.8 +/- 8.2% in control subjects, NS), coronary blood flow increase in the left anterior descending artery (mean flow velocity measured by intracoronary Doppler multiplied by the cross-sectional area measured by digital angiography) was significantly lower in diabetic patients than in control subjects (14.7 +/- 19.8 vs. 75.5 +/- 13.5%, respectively; P = 0.0001). In addition, when there was a positive correlation between the two parameters in control subjects (r = 0.651, P < 0.01), there was no relationship in diabetic patients (r = 0.054). In conclusion, vasodilation of the coronary microcirculation in response to sympathetic stimulation evoked by the cold pressor test is impaired in type 2 diabetic patients without epicardial artery lesions. This microvascular impairment during sympathetic stimulation may explain exercise-induced myocardial perfusion abnormalities observed in these patients and may impair microcirculatory coronary vasodilation during current life stress episodes such as exercise, mental stress, or cold exposition.

Agreement between coronary flow velocity reserve and stress echocardiography in intermediate‐severity coronary stenoses

Visual and quantitative assessments of percent diameter stenosis on coronary angiography correlate poorly with functional testing, particularly in intermediate-severity (40%-70%) lesions, yet are frequently relied on to make decisions regarding revascularization. Coronary flow velocity reserve (CFVR) and relative CFVR (RCFVR) are promising methods for on-line functional assessment of lesion severity in the catheterization laboratory. We sought to determine the agreement between maximal, mean, and relative CFVR and stress echocardiography in intermediate-severity stenoses. The results of exercise or dobutamine stress echocardiography and CFVR measured by intracoronary Doppler were compared in 28 patients referred for assessment of intermediate-severity stenoses, using 15 patients with either angiographically normal coronary arteries or diameter stenoses > 70% as reference groups. CFVR was measured at least three times in response to a bolus of adenosine in the target vessel distal to the stenosis. RCFVR (target/normal vessel CFVR) was also measured in 27 patients. Maximal, mean (of three measures), and relative CFVR were calculated. CFVR > or = 2.0 and RCFVR > or = 0.75 were accepted as normal. A minority (29%) of patients in the intermediate-severity stenosis group had a positive test by either method. There was good to very good agreement between stress echocardiography and maximal CFVR (84%, kappa = 0.62, P < 0.0001) and RCFVR (81%, kappa = 0.59, P < 0.001) across the entire patient cohort, though in the intermediate subgroup concordance was only fair. Using the mean (of three measures of) CFVR for the same comparison improved the agreement in the intermediate subgroup to good (86%, kappa = 0.58, P = 0.002), and in the entire cohort the agreement was very good (88%, kappa = 0.74, P < 0.0001). There was only fair correlation between measures of CFVR and percent coronary stenosis. CFVR improved from 1.8 +/- 0.8 to 2.7 +/- 0.7 after percutaneous intervention (n = 12, P < 0.0001). These results suggest that there is good agreement between CFVR and stress echocardiography across a wide range of coronary lesion severity. The mean of three CFVR measurements distal to the target vessel stenosis increases diagnostic accuracy. Intracoronary Doppler flow velocity measurements at the time of cardiac catheterization may facilitate improved decision-making by providing the ability to assess the functional significance of coronary stenoses on-line.

Effects of mental stress on coronary epicardial vasomotion and flow velocity in coronary artery disease: relationship with hemodynamic stress responses

OBJECTIVESThis study examines the prevalence and hemodynamic determinants of mental stress-induced coronary vasoconstriction in patients undergoing diagnostic coronary angiography.BACKGROUNDDecreased myocardial supply is involved in myocardial ischemia triggered by mental stress, but the determinants of stress-induced coronary constriction and flow velocity responses are not well understood.METHODSCoronary vasomotion was assessed in 76 patients (average age 59.9 ± 10.4 years; eight women). Coronary flow velocity responses were assessed in 20 of the 76 patients using intracoronary Doppler flow. Repeated angiograms were obtained after a baseline control period, a 3-min mental arithmetic task and administration of 200 μg intracoronary nitroglycerin. Arterial blood pressure (BP) and heart rate assessments were made throughout the procedure.RESULTSMental stress resulted in significant BP and heart rate increases (p < 0.001). Coronary constriction (>0.15 mm) was observed in 11 of 59 patients with coronary artery disease (CAD) (18.6%). Higher mental stress pressor responses were associated with more constriction in diseased segments (rΔSBP = −0.26, rΔDBP = −0.30, rΔMAP = −0.29; p’s < 0.05) but not with responses in nonstenotic segments. The overall constriction of diseased segments was not significant (p > 0.10), whereas a small but significant constriction occurred in nonstenotic segments (p = 0.04). Coronary flow velocity increased in patients without CAD (32.2%; p = 0.008), but not in patients with CAD (6.4%; p = ns). Cardiovascular risk factors were not predictive of stress-induced vasomotion in patients with CAD.CONCLUSIONSCoronary vasoconstriction in angiographically diseased arteries varies with hemodynamic responses to mental arousal. Coronary flow responses are attenuated in CAD patients. Thus, combined increases in cardiac demand and concomitant reduced myocardial blood supply may contribute to myocardial ischemia with mental stress.

Electron-beam computed tomography permits accurate quantitation of long-term changes in myocardial perfusion: a follow-up study in comparison to intracoronary doppler ultrasound Stefan M�hlenkamp, Amir Lerman, Thomas R. Behrenbeck, Lilach O. Lerman, Patricia E. Lund, Patrick F. Sheedy, II, Erik L. Ritman. Mayo Clinic and Foundation, Dept of Physiology and Biophysics, Rochester, MN

Electron-beam computed tomography permits accurate quantitation of long-term changes in myocardial perfusion: a follow-up study in comparison to intracoronary doppler ultrasound Stefan M�hlenkamp, Amir Lerman, Thomas R. Behrenbeck, Lilach O. Lerman, Patricia E. Lund, Patrick F. Sheedy, II, Erik L. Ritman. Mayo Clinic and Foundation, Dept of Physiology and Biophysics, Rochester, MN

Cost-effectiveness Analysis of Intravascular Ultrasound Guided Percutaneous Coronary Intervention versus Conventional Percutaneous Coronary Intervention

Objective - Investigation of the cost-effectiveness of intravascular ultrasound (IVUS) guided percutaneous coronary intervention (PCI) compared to PCI guided by coronary angiography (CAG). Methods - One hundred and eight men referred for PCI, were randomized to IVUS or CAG guided PCI. After 6 months, the patients were subjected to a study related clinical and invasive follow-up investigation by CAG, IVUS and intracoronary Doppler flow measurements. Incremental costs of IVUS guided procedures and costs of reinterventions were estimated using the Activity Based Costing (ABC) method. Results - Patients randomized to IVUS guided PCI experienced an improved clinical outcome, with lower angina levels than patients in the CAG guided group. The initial cost of performing IVUS guidance was increased due to extra procedure time, IVUS catheters and slightly more balloons and stents, but fewer patients in the IVUS guided group needed re-intervention. Overall, these savings outweighed the initial cost increase. Conclusion - Our data suggest that when performing IVUS guided PCI, costs as well as benefits increase. The increased benefits measured as cost savings resulting from less restenosis outweigh the cost increase from performing the IVUS guided PCI as opposed to CAG guided PCI.

Provisional stenting in small vessels

Based on the currently available data, the strategy of routine stent placement in unselected lesions located in small coronary arteries provides good immediate results but is still associated with a high incidence of in-stent restenosis. Randomized trials comparing elective stenting with balloon angioplasty have not provided the demonstration that routine stenting is the best strategy for percutaneous intervention in coronary arteries with a reference diameter smaller than 2.75-3.0 mm. This paper describes the rationale for provisional stenting in this clinical setting and reviews the role of quantitative coronary angiography, intracoronary ultrasound and intracoronary Doppler measurements in the identification of lesions that would benefit from adjunctive stent placement after balloon angioplasty and in guiding stent implantation.

Correlations between Coronary Flow Reserve and the Presence of Viable Myocardium after Acute Anterior Myocardial Infarction

Background : Coronary flow reserve (CFR) was defined as the ability to increase coronary blood flow maximally in response to demand. The presence of viable myocardium in an infarcted zone indicates the presence of an intact microvasculature. We hypothesized that coronary flow reserve, which assesses the microcirculation, might be associated with the presence of viable myocardium. Methods : Thirty seven patients with acute anterior myocardial infarction (mean age 55±10, 25 males) were enrolled and abnormal 127 segments were analyzed. Dobutamine stress echocardiography (5 to 20 g/kg/min) was performed before coronary angiography (6±3 days after acute myocardial infarction (AMI)). Coronary flow reserve in infarct-related artery was measured at distal site to lesion immediately after successful angioplasty (7±2 days after AMI, with residual stenosis less than 20%) by using intracoronary Doppler flow wire. And follow-up 2-dimentional transthoracic echocardiography was performed in 26 patients during 333±161 (range of 109-780) days after acute myocardial infarction. Improvement of wall motion at least one segment by one more grade in dobutamine stress echocardiography was defined as contractile reserve. Viable myocardium was defined as the improvement of wall motion in transthoracic echocardiography during follow-up periods. Results : In 26 patients, viable myocardium was detected in 19 patients (73%) and their mean CFR was 1.74±0.42, which was significantly increased than 1.16±0.14 of CFR of patients without viable myocardium (p<0.001). The agreement of CFR score and presence

The physiological role of endogenous endothelin in the regulation of human coronary vasomotor tone

OBJECTIVESThe study was done to investigate the physiological role of endogenous endothelin-1 in the human coronary circulation by studying the effect of an intracoronary infusion of the specific endothelin receptor subtype A (ETA) receptor antagonist BQ123 on coronary vasomotor tone.BACKGROUNDEndothelin-1 contributes to the maintenance of peripheral vascular tone in humans. However, its physiological role in the human coronary vasculature is unknown.METHODSWe studied 12 patients (mean age 54.7 ± 2.5 years, 3 men) undergoing cardiac catheterization for investigation of atypical chest pain, with angiographically normal coronary arteries. Coronary artery cross-sectional area was measured with digital quantitative coronary angiography, and coronary blood flow was assessed with an intracoronary Doppler flow wire. Flow-mediated (adenosine, 18 μg) and agonist-mediated (substance P, 20 pmol/min for 2 min) endothelial responses were measured prior to study. BQ123 (40 nmol/min for 15 min and monitored for a further 15 min) was infused into the left coronary artery.RESULTSThe BQ123 caused significant dilation of the proximal (artery cross-sectional area: 8.08 ± 0.9 to 8.88 ± 0.9 mm2; p < 0.05), mid (5.32 ± 0.8 to 6.49 ± 0.8 mm2; p < 0.001) and distal study vessel (2.11 ± 0.2 to 2.50 ± 0.2 mm2; p < 0.05). There was an increase in coronary blood flow (26.8 ± 2.8 to 32.8 ± 3.4 ml/min; p < 0.001) but no change in systemic hemodynamics. Baseline flow- or substance P-induced epicardial vasodilation did not correlate with the degree of vasodilation induced by BQ123.CONCLUSIONSThese data uncover a role of endogenous endothelin-1 in the maintenance of basal vasomotor tone in patients with angiographically normal coronary arteries.

Immediate changes of collateral function after successful recanalization of chronic total coronary occlusions.

Coronary collaterals are essential to maintain myocardial function in chronic total coronary occlusions (TCOs). The aim of the present study was to assess the collateral circulation in TCOs before coronary angioplasty and to determine the recruitable collateral perfusion after recanalization by use of intracoronary Doppler flow velocimetry. In 21 patients with TCOs (duration >4 weeks), Doppler recordings of basal collateral flow were obtained before the first balloon inflation. Angioplasty was performed with stent implantation in all lesions. At the end of the procedure, recruitable collateral flow was measured during a repeat balloon inflation. The collateral flow index (CFI) was calculated from the velocity integral during the occlusion/velocity integral of antegrade flow. In 17 of 21 patients, angiography was repeated after 24 hours, and CFI was reassessed. Average peak velocity of collateral flow was 10.9+/-5.6 cm/s with a predominantly systolic flow (diastolic/systolic velocity ratio <0.5) compared with antegrade flow (diastolic/systolic velocity ratio >1.5). After recanalization, the average peak velocity of recruitable collateral flow dropped by >50% to 4.7+/-2.5 cm/s. CFI fell from 0.48+/-0.25 to 0.21+/-0.16 (P:<0.001). There was no further change of CFI during the following 24 hours. CFI was higher in patients with preserved regional ventricular function than in those with akinetic myocardium (0.57+/-0.23 versus 0.38+/-0.12, P:<0.05). Collateral circulation in TCO provided 50% of antegrade coronary flow. A considerable fraction of collateral flow was immediately lost after recanalization, indicating that TCO may not remain protected from future ischemic events by a well-developed collateral function.

Functional Assessment of Coronary Arteries by Poststenotic Intravascular Doppler Ultrasound

This study sought to delineate the impact of the rate pressure product on intraluminal Doppler velocity measurements and to determine the relation between poststenotic vasodilator reserve and percent luminal obstruction in coronary vessels. Twenty patients with single-vessel coronary disease were studied prior to coronary angioplasty and at follow-up 6 months later. Intracoronary velocity reserve after administration of adenosine was measured distal to the stenosis with a Doppler-tipped guide wire and was compared to quantitative coronary angiography and adenosine myocardial perfusion scintigraphy. The rate pressure product was confirmed as significant covariate (ANCOVA, p < 0.005) of intracoronary Doppler reserve. When normalized to rate pressure product, poststenotic Doppler velocity reserve in stenosed arteries was significantly lower than in patent arteries as classified by quantitative coronary angiography (1.7 ± 0.6 vs. 2.9 ± 0.5, p < 0.001) and perfusion scintigraphy (1.5 ± 0.4 vs. 2.8 ± 0.5, p < 0.001). Normalized Doppler velocity reserve showed a nonlinear but highly significant relation to percent area stenosis [y = 3.0·(1 – exp[0.081 (x – 100)]), p < 0.001]. When normalized Doppler velocity reserve was less than 2.0, coronary disease was identified with 95% specificity and 94% sensitivity in comparison to perfusion scintigraphy. Thus, in coronary arteries poststenotic Doppler reserve and percent area stenosis show a significant nonlinear relation. Doppler velocity reserve when normalized to rate pressure product can be used to characterize the hemodynamic impact of coronary obstructions.

Acute effects of ACE inhibition on coronary endothelial dysfunction.

The prerequisite of atherosclerosis, endothelial dysfunction, is characterised by impaired endothelium-dependent vasodilation caused by the reduced bioavailibility of nitric oxide (NO). In order to assess the role of acute ACE inhibition in this setting, coronary arterial endothelial function was quantified following acute intracoronary administration of the angiotensin-converting enzyme (ACE) inhibitor quinapril. Twenty-one patients with non-limiting coronary artery disease were studied before and after acute intracoronary administration of 10 mg quinapril. Nine patients received pre-treatment with the angiotensin AT(1)-receptor antagonist losartan (2 x 50 mg, p.o.). Coronary cross-sectional diameter was measured via quantitative angiography and microvascular reaction was investigated by intracoronary Doppler flow measurement during intracoronary infusion of 0.1 to 10 micromol/l acetylcholine. Quinapril acutely improved endothelial dysfunction on the macro- as well as the microvascular level. Losartan did not alter macrovascular function but facilitated microvascular endothelial function. Acute quinapril application led to no further improvement of endothelial dysfunction in patients pre-treated with losartan. Acute quinapril infusion improved endothelial function in patients with coronary heart disease. Treatment with the AT(1)-receptor antagonist losartan led to a slight improvement in microvascular endothelial function, but pre-treatment with losartan blunted the vascular effect of quinapril, suggesting that the combination of ACE inhibition and AT(1)-receptor antagonism may not exert a synergistic benefical impact on the coronary vasculature.

Minimally invasive evaluation of coronary microvascular function by electron beam computed tomography.

We previously demonstrated that in vivo electron-beam computed tomography (EBCT)-based indicator-dilution methods provide an estimate of intramyocardial blood volume (BV) and perfusion (F), which relate as BV=aF+b radicalF, where a characterizes the recruitable (exchange) and b the nonrecruitable (conduit) component of the myocardial microcirculation. In the present study, we compared BV and F with intracoronary Doppler ultrasound-based coronary blood flow (CBF) as a method for detecting and quantifying differential responses of these microvascular components to vasoactive drugs in normal (control) and hypercholesterolemic (HC) pigs. BV and F values were obtained from contrast-enhanced EBCT studies in 14 HC and 14 control pigs. BV, F, and CBF values were obtained at baseline (intracoronary infusion of saline) and after 5 minutes each of intracoronary infusion of adenosine (100 microgram. kg(-1). min(-1)) and nitroglycerin (40 microgram/min). BV and CBF reserves in response to adenosine were attenuated in HC pigs compared with controls (90+/-36% versus 127+/-42%, P<0.03, and 485+/-182% versus 688+/-160%, P<0.01, respectively). The relationship between BV and F showed consistently lower recruitable BV in HC versus control pigs. Nonrecruitable BV reserve in response to adenosine was attenuated in HC compared with controls (77+/-20% versus 135+/-28%, P<0.001). Our findings are consistent with HC-induced impairment of intramyocardial resistance vessel function. EBCT technology allows minimally invasive evaluation of intramyocardial microcirculatory function and permits assessment of microvascular BV distribution in different functional components. This method may be of value in evaluating the coronary microcirculation in pathophysiological states such as hypercholesterolemia.

Safety of intracoronary Doppler flow measurement

Background With the introduction of Doppler-tipped guide wires, intracoronary Doppler flow measurement has been increasingly accepted as an additional diagnostic approach in the catheterization laboratory. However, the safety of intracoronary Doppler flow measurement has not been well-investigated. The purpose of our study was to evaluate the safety of intracoronary Doppler flow measurement using the Doppler FloWire (Cardiometrics, Mountain View, Calif). Methods and Results A total of 906 patients were examined by intracoronary Doppler with a 0.014-inch or an 0.018-inch Doppler FloWire. For coronary flow reserve measurement, intracoronary injection of adenosine or papaverine was used. Of the patients studied, 77 were cardiac transplant recipients and 829 were patients who had not received a transplant, of whom 617 had undergone diagnostic coronary procedures and 212 had coronary interventions. In 27 (2.98%) of 906 patients adverse cardiac events were observed. Fifteen (1.66%) of 906 patients had severe transient bradycardia develop (asystole or second- to third-degree atrioventricular block) after intracoronary administration of adenosine, 14 of which occurred in the right coronary artery and 1 in the left anterior descending artery. Nine (0.99%) of 906 patients had coronary spasm during the passage of the Doppler wire (5 in the right coronary artery, 4 in the left anterior descending artery). Two (0.22%) of 906 patients had ventricular fibrillation during the procedure. Hypotension with bradycardia and ventricular extrasystole each occurred in 1 (0.11%) of 906 patients. The incidence of complication was significantly higher in transplant recipients than in patients who underwent either diagnostic or interventional procedures (12.99% vs 2.43% vs 0.94%, P <.001). The Doppler measurements in the right coronary artery were associated with a higher incidence of complications, especially bradycardia, compared with the left anterior descending and the left circumflex arteries (right coronary, 5.87% vs left anterior descending, 1.05% vs left circumflex, 0.17%; P <.001). All complications were cured medically. Conclusion Intracoronary Doppler flow measurement with Doppler wires and intracoronary administration of adenosine is a safe method. However, severe complications such as bradycardia and coronary spasm can occur. Attention should be paid to the examination of the right coronary artery, especially in heart transplant recipients. (Am Heart J 2000;140:502-10.)

Angiographic and clinical outcome of mild to moderate nonocclusive unstented coronary artery dissection and the influence on coronary flow velocity reserve

Limited data are available regarding the angiographic healing rate and physiologic impact of coronary artery dissections. Therefore, we studied the impact of coronary dissections on coronary flow velocity and outcome as well as their healing rate at 6-month follow-up balloon angioplasty. Of 297 patients who underwent balloon angioplasty, 225 underwent intracoronary Doppler measurements and 184 had Doppler and angiographic assessment at 6-month follow-up. Dissections were scored by an independent core lab (Cardialysis BV) and divided in 4 groups: mild (types A to B), moderate (type C), severe (D to F), and patients without dissections. Severe dissections (types D to F) were excluded from the analysis. Clinical, angiographic, and Doppler data were compared among the remaining 3 patient groups. From the 67 dissections detected after balloon angioplasty, only 3 (4.5%) remained unhealed at follow-up. Immediately after balloon angioplasty, the moderate dissection group was associated with a lower coronary flow velocity reserve than the patients with mild (2.16 ± 0.60 vs 2.82 ± 1.00, p = 0.037) or no dissections (2.16 ± 0.60 vs 2.71 ± 0.88, p = 0.046), respectively. In addition, higher recurrence of angina at 30 days was observed in the moderate group rather than in the mild group (5 [50%] vs 8 [16%], p = 0.0160) and in the patients without dissections (11 [12%], p = 0.007). After standard balloon angioplasty, the occurrence of unhealed dissections is a rare phenomenon. An impaired coronary flow reserve was observed after the development of nonocclusive type C dissections, which was associated with a worse short-term outcome.

Acute effects of urinary bladder distention on the coronary circulation in patients with early atherosclerosis

OBJECTIVESWe sought to examine whether distention of the urinary bladder, a physiologic stimulus, could induce impaired coronary circulation in patients with early atherosclerosis.BACKGROUNDDistention of the urinary bladder reflexively causes an increase in sympathetic activity. The effect of such distention on the coronary circulation in patients with early atherosclerosis remains unknown.METHODSTo assess the effect of bladder distention on coronary dynamic forces, epicardial and microvascular responses were measured with an intracoronary Doppler flow wire in 40 patients with early atherosclerosis (<50% diameter stenosis). Patients were randomized into two groups according to whether they did not (group 1, n = 20) or did have (group 2, n = 20) pretreatment with an alpha1-adrenergic receptor blocker (oral doxazosin, 2 mg). Coronary flow velocity was monitored by quantitative coronary angiography at baseline, during urinary bladder distention and after intracoronary nitroglycerin injection.RESULTSBladder distention significantly decreased the coronary diameter in the stenotic segments (p < 0.001), decreased coronary blood flow (p < 0.001) and increased coronary resistance (p < 0.001), as compared with baseline values, in group 1 patients. In group 2 patients with bladder distention, the angiographic variables did not show significant changes, as compared with baseline values. No significant differences were noted between the groups in the responses of the angiographic variables after nitroglycerin administration.CONCLUSIONSThe present study shows, for the first time, that urinary bladder distention caused vasoconstriction of coronary conduit and resistance vessels involved mechanisms related to alpha1 adrenoceptors. Pretreated administration of doxazosin reversed the changes toward baseline. Vasoconstriction during bladder distention can be relieved after nitroglycerin administration, suggesting an unchanged responsiveness of vascular smooth muscle cells to such distention.

Corrected coronary flow velocity reserve: a new concept for assessing coronary perfusion

OBJECTIVESIn order to limit the variability of coronary flow velocity reserve (CFVR), we analyzed which factors independently affect CFVR and established a new parameter integrating these factors.BACKGROUNDCoronary flow velocity reserve (CFVR) is a frequently used parameter for evaluating the physiological significance of epicardial stenosis and microvascular function. Since CFVR measurements are done in substantially different hemodynamic and clinical situations, interpretation of CFVR requires correction for major influencing factors.METHODSIn 141 patients with angina-like symptoms and angiographically unobstructed coronary arteries, intracoronary Doppler measurements were performed in at least two coronary vessels. Coronary flow velocity reserve was calculated as the ratio of hyperemic average peak velocity (hAPV), after intracoronary bolus of adenosine, to baseline average peak velocity (bAPV).RESULTSAnalysis of covariance revealed that only bAPV (p < 0.0001) and age (p < 0.0001) were independent factors influencing CFVR. Based on a regression model for estimation of predicted CFVR values, individual CFVR values (CFVRind) obtained at different bAPV and age were transformed in corrected CFVR values (CFVRcorr) by relating them to a mean bAPV of 15 cm/s and a mean age of 55 years. The transformation from CFVRind into CFVRcorr for the left anterior descending artery can be done by using the following equation: CFVRcorr = 2.85∗CFVRind∗10 0.48∗log(bAPV) + 0.0025∗age − 1.16. When applying this new parameter to conditions assumed to cause microvascular dysfunction, analysis showed that only patients with diabetes showed a significant decrease of traditional CFVR and CFVRcorr, whereas a history of hypertension and current smoking habit had no influence on CFVRcorr.CONCLUSIONSThe concept of CFVRcorr standardizes CFVR for bAPV and age as the major physiological determinants. Especially in patients with microvascular dysfunction, this approach may help to discriminate between conditions directly affecting vasodilator reserve and conditions primarily affecting bAPV.

Angiographical and Doppler flow-derived parameters for assessment of coronary lesion severity and its relation to the result of exercise electrocardiography. DEBATE study group. Doppler Endpoints Balloon Angioplasty Trial Europe.

Evaluation of angiographical and intracoronary Doppler-derived parameters of coronary stenosis severity. A total of 225 patients with one-vessel disease were studied before PTCA and at 6 months follow-up. Exercise electrocardiography was performed to document presence (n = 157) or absence (n = 138) of an ST segment shift (> or =0.1 mV). Intracoronary blood flow velocity analysis was performed to determine the proximal/distal flow velocity ratio, the distal diastolic/systolic flow velocity ratio and coronary flow velocity reserve. Receiver operator characteristic curves were calculated to assess the predictive value of these variables compared with the exercise test. The distal coronary flow velocity reserve demonstrated the best linear correlation for both percentage diameter stenosis and minimum lumen diameter (r = 0.67 and r = 0.66; P<0.01), compared to the diastolic/systolic flow velocity ratio (r = 0.19 and r = 0.14; P<0.01) and the proximal/distal flow velocity ratio (r = 0.03 and r = 0.07; not significant). The areas under the curve were 0. 84+/-0.02; 0.82+/-0.03 and 0.83+/-0.03 for diameter stenosis, minimum lumen diameter and coronary flow velocity reserve, respectively. Logistic regression analysis revealed that the percentage diameter stenosis or minimum lumen diameter and coronary flow velocity reserve were independent predictors for the result of stress testing. The distal coronary flow velocity reserve is the best intracoronary Doppler parameter for evaluation of coronary narrowings. Angiographical estimates of coronary lesion severity and distal coronary flow velocity reserve are good and independent predictors for the assessment of functional severity of coronary stenosis, emphasizing the complementary role of these parameters for clinical decision making.