Doppler Guidewire Research Articles

Abstract 4472: Validation of an Angiography based Algorithm to Calculate the Coronary Flow Reserve

Coronary Flow Reserve (CFR) is defined as the ratio between flow in a coronary vessel at maximum hyperemia and at rest. It is considered as a marker for the integrity of the coronary mircrocirculation. The measurement is typically performed using dedicated Doppler guidewires and pharmacologic stimulation (CFRdoppler). This measurement is costly, time-consuming and potentially harmful since the Doppler wire has to be advanced into the coronary artery. Today a new angiography based algorithm is available using the first pass kinetic of the injected contrast dye to calculate the CFR. The aim of the present study was, to compare this new algorithm with the conventionally Doppler wire technique. CFR measurements were performed during 27 coronary interventions (10 female, mean age 64 ± 11 years). CFR doppler (Flowire, Volcano corp.) was calculated as the ratio of average peak velocity (APV) during hyperemia (140μg/kg·min −1 ) and at rest. For calculation of angiographic CFR angio , two angiograms were analised, one at base line flow and one at hyperemia state. CFR was calculated by the ratio between the hyperemia representing numbers of the logarithmic Time Density Curve (TDC) linear slope, multiplied with the coronary cross-sections, and the respective baseline representing numbers. An excellent correlation was found between the CFR doppler and the CFR angio values: CFR angio = 1× CFR doppler (r=0.87; p<0.0001). The average absolute difference between both indexes was 0.36±0.31. Angiographic measurement of CFR is a feasible and valid method in daily routine with an excellent correlation to doppler-wire derived measurements and moreover less potential of adverse interventional health effects.

Clinical Implications of Distal Embolization During Coronary Interventional Procedures in Patients With Acute Myocardial Infarction: Quantitative Study With Doppler Guidewire

This study sought to investigate the timing and amount of embolic particles generation during the percutaneous coronary intervention (PCI) procedure and studied the relationship between embolic burden and coronary blood flow and myocardial damage. Distal embolization is a major complication of PCI. The Doppler guidewire (DGW) can detect the embolic particles as high-intensity transient signals (HITS) during the PCI procedure. We prospectively studied 37 patients with acute myocardial infarction (MI). Under monitoring with the DGW, we performed first and second balloon angioplasty, followed by stenting and post-high-pressure dilatation. Left ventricular ejection fraction (LVEF) (%) and regional wall motion (RWM) (standard deviation/chord) were measured on days 1 and 22. The HITS were detected in 35 of 37 patients. The number of HITS was the greatest after stenting (16 +/- 18) followed by first balloon inflation (5 +/- 4). There was a significant correlation between the total number of HITS and the corrected Thrombolysis In Myocardial Infarction frame count (r = 0.52, p = 0.003) and a significant weak inverse correlation between the total number of HITS and changes in LVEF and RWM (r = 0.37, p = 0.03 and r = 0.35, p = 0.04, respectively). Distal embolization is common during PCI in patients with acute MI, and the majority of HITS were observed after stenting. An increase in the total number of HITS is associated with reduced coronary blood flow, and is weakly associated with poor recovery of left ventricular function.

Isolated Atrial Microvascular Dysfunction in Patients With Lone Recurrent Atrial Fibrillation

The purpose of this study was to assess atrial myocardial perfusion in patients with lone recurrent atrial fibrillation (LRAF). Although acute atrial ischemia has been implicated in the pathogenesis of atrial fibrillation, there are few data concerning human atrial myocardial perfusion and none for patients with LRAF. Sixteen patients with LRAF and 15 control subjects with suitable coronary anatomy underwent time-averaged peak coronary blood flow velocity (APV) measurements (cm/s), using a Doppler guidewire in the proximal left circumflex coronary artery (LCx) and in the left atrial circumflex branch (LACB), at baseline (b) and after adenosine administration to achieve maximal hyperemia (h). Coronary flow reserve was defined as h-APV/b-APV. Although there were no statistically significant differences in b-APV between patients with LRAF and control subjects or between the LACB and LCx, there were significant group (p = 0.002), artery (p = 0.001), and interaction (p < 0.001) effects at maximal hyperemia. In patients with LRAF, the h-APV and coronary flow reserve of the LACB (30.4 +/- 9.5 cm/s and 2.2 +/- 0.4, respectively) were significantly lower than in the LACB of the control subjects (45.8 +/- 12.8 cm/s [p < 0.001] and 2.9 +/- 0.5 [p = 0.001], respectively) or in the patients' LCx (43.0 +/- 10.9 cm/s [p = 0.001] and 3.1 +/- 0.6 [p < 0.001], respectively). This study confirms for the first time isolated atrial myocardial perfusion abnormalities in patients with LRAF and coronary flow reserve impairment, indicating that microvascular dysfunction is a pathophysiological substrate associated with this arrhythmia.

Acute hyperglycaemia prevents the protective effect of pre-infarction angina on microvascular function after primary angioplasty for acute myocardial infarction

Background:Acute hyperglycaemia has been associated with impaired microvascular function after acute myocardial infarction (AMI), whereas pre-infarction angina (PIA) occurring shortly before the onset of AMI has been shown to reduce...

Single-Scope EUS Guided Cyst Access, Debridement and Drainage Using a Novel Therapeutic Forward Viewing Echoendoscope

Background: Despite reports of successful endoscopic cystgastrotomies, there remain technical limitations related to current CLA echoendoscopes - namely the oblique angle properties that result in a weakened transfer of force, difficult deployment of larger-bore accessories and its tunneling in the gastric wall. In addition, and most importantly, the technique requires the use an additional endoscope to perform cyst debridement with its potential loss of access during endoscope exchange. A novel therapeutic echoendoscope that shifts the endoscopic and ultrasound orientation from oblique to forward viewing has recently been prototyped. Methods: Phase I/II study of pancreatic cyst drainage using a forward viewing echoendoscope. A standardized approach of cyst drainage technique, including cyst localization, needle puncture under doppler ultrasound guidance, guidewire insertion, balloon dilation, cyst debridement and stent placement with or without nasocystic catheter, were used in order to study the technical advantages and disadvantages of the forward viewing endoscope. Patients were followed to assess symptom and cyst resolution. Our local Institutional Review Board approved the study. Results: Six consecutive patients who were referred for pancreatic cyst drainage were enrolled. The majority of patients were men (83%) with a mean age of 50 ± 20 years and had developed a cyst due to acute pancreatitis of various etiologies. The mean size of the cysts was 10 cm (range 6 to 12 cm) and they were located predominantly in the pancreatic body (83%). We gained cyst access using a 19-gauge needle followed by balloon dilation in 2 patients and with a Cystotome in 4. All cysts had successful stent drainage. Direct cystoscopy and debridement were achieved in 4 cases. Inability to directly enter the cyst with the echoendoscope occurred due to cyst location in the distal stomach in one case and inadequate cyst adherence to the stomach wall in the other. Conclusion: The forward viewing echoendoscope showed a number of promising mechanical advantages for pancreatic cyst drainage. Its most compelling feature was the ability to perform imaging and endoscopic interventions with the same instrument - for single scope ultrasound guided cyst access, debridement and stent drainage.

Comparison of effect between nitrates and calcium channel antagonist on vascular function in patients with normal or mildly diseased coronary arteries

The comparative long-term antianginal efficacy of long-acting nitrates versus calcium channel antagonists remains unclear. The goal of the present study was to compare the coronary endothelial cell function and coronary artery vasoconstriction between patients with normal or mildly diseased coronary arteries treated with long-acting nitrates or calcium channel antagonists. Forty-two patients suspected to have angina pectoris and with normal or mildly diseased coronary arteries underwent Doppler flow study of the left anterior descending coronary artery. All patients were suspected to have angina pectoris and were receiving either long-acting nitrates (n = 18; Nitrates group) or calcium channel antagonists (n = 24; Ca-antagonists group) for at least 1 year. Vascular reactivity was assessed by intracoronary administration of papaverine, acetylcholine (Ach), and nitroglycerin using a Doppler guidewire. Segments that showed the greatest constrictive response to Ach were used for assessment of vasoconstriction. The percent increase in coronary blood flow (CBF) and coronary artery diameter (CAD) induced by Ach was significantly smaller in the Nitrates group than in the Ca-antagonists group (33% +/- 74% vs 83% +/- 77%, P < 0.05; -3% +/- 16% vs 11% +/- 12%, P < 0.01, respectively). The percent diameter reduction in the region of greatest constrictive response to Ach was significantly greater in the Nitrates group than in the Ca-antagonists group (44% +/- 39% vs 15% +/- 32%, P < 0.02). Long-term treatment with long-acting nitrates may produce less favorable effects on coronary endothelial function and the constrictive response to Ach when compared with long-acting calcium channel antagonists in patients with normal or mildly diseased coronary arteries.

Relationship of Admission Neutrophil Count to Microvascular Injury, Left Ventricular Dilation, and Long-Term Outcome in Patients Treated With Primary Angioplasty for Acute Myocardial Infarction

The relationship of admission neutrophil count to the degree of microvascular injury, left ventricular (LV) volume, and long-term outcome after acute myocardial infarction (AMI) was examined in the present study. The study group comprised 228 consecutive patients with a first anterior wall AMI who underwent primary angioplasty within 12 h of onset. The degree of microvascular injury was evaluated by Doppler guidewire. Adverse cardiac events were recorded during an average follow-up of 52+/-28 months. Using a receiver-operating characteristic analysis, a neutrophil count >or=7,260 cells/mm(3) was the best predictor of future cardiac events. By regression analysis, the neutrophil count significantly correlated with diastolic deceleration time (r=-0.40, p<0.0001), coronary flow reserve (r=-0.43, p<0.0001), and LV end-diastolic volume at 4 weeks (r=0.32, p<0.0001). Kaplan-Meier survival analysis showed a higher incidence of adverse cardiac events in patients with a high neutrophil count (p=0.002). By multivariate analysis, a neutrophil count >or=7,260 cells/mm(3) was an independent predictor of long-term adverse cardiac events (odds ratio 3.8, p=0.002). Neutrophilia on admission is associated with impaired microvascular perfusion, LV dilation, and long-term adverse cardiac events in patients treated with primary angioplasty for AMI.

Hibernating Myocardium

See related article, pages 103–112 Winter hibernation carries the promise of rejuvenation in the spring. In a similar fashion, myocardial “hibernation” describes a clinical phenomenon in which patients with ischemic left ventricular dysfunction demonstrate improved cardiac function following bypass surgery.1 The signature of myocardial hibernation is decreased blood flow with preserved glucose uptake, as demonstrated by positron emission tomography imaging, and identifies individuals with ischemic cardiomyopathy who may benefit from revascularization.2 In experimental models of hibernating myocardium, oxygen consumption is reduced in the absence of active ischemia.3,4 This implies that hibernation is a coordinated response to balance myocardial energy utilization with energy production capacity.5 However, within hibernating myocardium, several morphological and functional changes have been observed that can identify regions in which complete revascularization may not result in normalization of contraction.6–10 In fact, those myocardial regions with the greatest metabolic abnormalities in the hibernating tissue demonstrate the longest delay in recovery.11 In the current issue, Page et al12 demonstrate that the process of hibernation is associated with altered expression of mitochondrial proteins. Using 2D differential-in-gel electrophoresis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry in a swine model of hibernation, they have found that key mitochondrial proteins associated with the electron transport chain are reduced. The functional importance of the decreased protein expression is documented by reduced activity measurements of the pyruvate dehydrogenase complex, cytochrome c oxidase, and citrate synthase. The parallel reductions in mitochondrial proteins and contractile function 5 months after placement of the coronary artery constrictor suggest that the “downregulation” of electron transport proteins is related to the reduced oxygen consumption. In fact, the reductions in ATPase correlate with the reduction in subendocardial blood flows in the hibernating myocardium. In addition, “upregulation” of several cytosolic proteins has been observed, including …

Abstract 3340: Coronary Flow Velocity Pattern Immediately After Percutaneous Coronary Intervention Predicts Left Ventricular Remodeling in Patients with Acute Myocardial Infarction

Background: Studies using the Doppler guidewire have shown that coronary flow velocity (CFV) pattern in recanalized infracted arteries predicts recovery of regional left ventricular (LV) function, in-hospital complications, and long-term cardiac events. However, the relationship between the CFV pattern after reperfusion and serial changes in LV volumes is not clear. We postulated that the quantitative CFV measurement immediately after successful percutaneous coronary intervention (PCI) might be associated with the LV remodeling. To test this hypothesis, we prospectively analyzed the LV remodeling according to CFV parameters measured by the Doppler guidewire in patients with acute myocardial infarction (AMI). Methods: Consecutive 211 patients with first-time anterior AMI underwent successful PCI (&lt;50% residual stenosis with TIMI flow grade 2–3) and coronary flow measurement with the Doppler guidewire. The CFV spectrum provided the following parameters: time-averaged peak velocity (cm/s), systolic peak velocity (cm/s), and diastolic deceleration time (ms). Left ventriculograms obtained immediately after PCI and 6 months after the infarction were analyzed to measure the end-diastolic volume index and end-systolic volume index. The LV remodeling was defined as an increase in end-diastolic volume index ≥20%. Result: The optimal cutoff values to predict LV remodeling (defined as 6-month LV dilation ≥20%) were 20 cm/s for time-averaged peak velocity, 0 cm/s for systolic peak velocity and 550 ms for diastolic deceleration time (sensitivity=0.63, specificity=0.56; sensitivity=0.76, specificity=0.85; and sensitivity=0.85, specificity=0.85, respectively). Systolic peak velocity and diastolic deceleration time correlated to the LV end-diastolic volume index obtained 6 months after AMI(r= −0.67; p&lt;0.001 and r= −0.78; p&lt;0.001, respectively). Conclusions: The CFV pattern appears to be an accurate predictor of LV remodeling even in patients who received successful PCI in the left anterior descending coronary artery immediately after AMI. This index, therefore, identifies a subset of patients at-risk.

The Relationship Between Coronary Plaque Characteristics and Small Embolic Particles During Coronary Stent Implantation

We investigated the relationship between coronary plaque components and small embolic particles during stenting and examined the influence on the coronary microcirculation. In vivo tissue characterization of atherosclerotic plaques was introduced by the Virtual Histology intravascular ultrasound (VH-IVUS) system (Volcano Therapeutics, Inc., Rancho Cordova, California). The study consisted of 44 patients who underwent elective coronary stenting. Plaque characteristics were identified with VH-IVUS, and small embolic particles liberated during stenting were detected as high-intensity transient signals (HITS) with a Doppler guidewire. Coronary flow velocity reserve (CFVR) was also measured before and after stenting. Patients were divided into the tertiles according to the HITS counts: the lowest, HITS <5 (n = 16); the middle, 5 to 12 (n = 15); and the highest, >12 (n = 13). Dense calcium and necrotic core area identified with VH-IVUS were significantly larger in the highest tertile (lowest vs. middle vs. highest; dense calcium: 0.2 +/- 0.3 mm2 vs. 0.3 +/- 0.6 mm2 vs. 0.8 +/- 0.7 mm2, p = 0.007; necrotic core: 0.5 +/- 0.4 mm2 vs. 0.9 +/- 0.9 mm2 vs. 1.8 +/- 1.0 mm2, p < 0.001, respectively). Multivariate logistic regression analysis revealed only necrotic core area was an independent predictor of high HITS counts (odds ratio 4.41, p = 0.045). Furthermore, there was a significant negative correlation between the HITS count and CFVR after stenting (r = -0.35, p = 0.017). The necrotic core component identified with VH-IVUS is related to liberation of small embolic particles during coronary stenting, which results in the poorer recovery of CFVR.

Usefulness of Coronary Flow Reserve Immediately After Primary Coronary Angioplasty for Acute Myocardial Infarction in Predicting Long-Term Adverse Cardiac Events

Coronary flow reserve (CFR) evaluated immediately after reperfusion is thought to reflect the degree of microvascular injury and predict left ventricular (LV) functional recovery after acute myocardial infarction. It was hypothesized that CFR immediately after reperfusion would be predictive of the occurrence of long-term adverse cardiac events. Using a Doppler guidewire, CFR was evaluated immediately after primary coronary angioplasty in 118 consecutive patients with first anterior acute myocardial infarctions. Adverse cardiac events combining cardiac death, recurrent myocardial infarction, and congestive heart failure were recorded during an average follow-up period of 62 +/- 32 months. Using receiver-operating characteristic analysis, CFR </=1.3 was the best predictor of future cardiac events (sensitivity 86%, specificity 70%). Accordingly, patients were divided into 2 groups: those with CFR </=1.3 (n = 50) and those with CFR >1.3 (n = 68). Patients with CFR </=1.3 had significantly higher peak creatine kinase concentrations, lower LV ejection fractions, and higher LV volumes compared with patients with CFR >1.3. CFR was significantly correlated with the LV ejection fraction at 4 weeks (r = 0.50, p <0.0001) and LV end-diastolic volume at 4 weeks (r = -0.43, p <0.0001). Kaplan-Meier survival analysis showed a higher incidence of adverse cardiac events in patients with CFR </=1.3 (p <0.0001). In conclusion, CFR evaluated immediately after primary coronary angioplasty is a strong predictor of long-term adverse cardiac events after reperfused acute myocardial infarction.

Relation Between Neutrophil Counts on Admission, Microvascular Injury, and Left Ventricular Functional Recovery in Patients With an Anterior Wall First Acute Myocardial Infarction Treated With Primary Coronary Angioplasty

Increased neutrophil counts have been associated with an increased risk of adverse clinical events after acute myocardial infarction (AMI). We examined the association of neutrophil counts on admission with degree of microvascular injury and left ventricular functional recovery after primary coronary angioplasty in AMI. We studied 116 patients with a first anterior wall AMI who underwent primary coronary angioplasty within 12 hours of onset. Patients were categorized into 3 groups based on initial neutrophil count: low (<5,000/mm(3)), intermediate (5,000 to 10,000/mm(3)), and high (>10,000/mm(3)). Coronary flow velocity parameters were assessed immediately after reperfusion using a Doppler guidewire. We defined severe microvascular injury as the presence of systolic flow reversal and a diastolic deceleration time <600 ms. Echocardiographic wall motion was analyzed before revascularization and 4 weeks after revascularization. In patients with a high neutrophil count, systolic flow reversal was more frequently observed, diastolic deceleration time was shorter, and coronary flow reserve was lower. By regression analysis, neutrophil count significantly correlated with diastolic deceleration time (r = -0.38, p <0.0001), coronary flow reserve (r = -0.33, p = 0.0004), and score for change in wall motion (r = -0.36, p = 0.0004). Multivariate analysis showed that neutrophil count on admission was an independent predictor of severe microvascular injury (odds ratio 2.94, p = 0.02). In conclusion, neutrophilia on admission is associated with impaired microvascular reperfusion and poor functional recovery after primary coronary angioplasty.

Detection of Coronary Microembolization by Doppler Ultrasound in Patients With Stable Angina Pectoris Undergoing Elective Percutaneous Coronary Interventions

Intracoronary Doppler guidewires can be used for real-time detection and quantification of microembolism during percutaneous coronary interventions (PCIs). We investigated whether the frequency of Doppler-detected microembolism is related to the incidence of myonecrosis during elective PCI. The study population included 52 consecutive patients (aged 64+/-10 years; 36 men, 16 women) with coronary artery disease who underwent elective PCI of a single-vessel stenosis. Using intracoronary Doppler ultrasound, we compared the frequency of microembolism during PCI in 22 patients with periprocedural non-ST-segment elevation myocardial infarctions (pNSTEMI) and 30 patients without pNSTEMI. The 2 groups were comparable with regard to their clinical and procedural characteristics. In the group with pNSTEMI, the total number of coronary microemboli after PCI (27+/-10 versus 16+/-8, P<0.001) was higher than in the group without pNSTEMI. Although high-sensitivity C-reactive protein plasma levels were similar before PCI (2.9+/-2.2 versus 3.4+/-1.7 mg/L, P=NS), they were higher in the group with pNSTEMI after PCI (12.6+/-10.4 versus 6.1+/-5.1 mg/L, P<0.05). Microembolic count independently correlated to postprocedural cardiac troponin I elevation (r=0.565, P<0.001), coronary flow velocity reserve (r=-0.506, P<0.001), and baseline average peak velocity (r=0.499, P<0.001). Patients with pNSTEMI had a significantly higher frequency of coronary microembolization during PCI, and their systemic inflammatory response and microvascular impairment after PCI were more pronounced. Intracoronary Doppler ultrasound provides evidence that pNSTEMI in patients undergoing elective PCI is caused by microembolization during the procedure.

Detection and quantification of embolic particles during percutaneous coronary intervention to stable plaque: It correlates to coronary flow dynamics and myocardial damage

We detected embolic particles liberated from plaque during percutaneous coronary intervention (PCI) as high-intensity transient signals (HITS) with a Doppler guidewire and studied their impact on coronary flow dynamics and the myocardium in patients with stable angina pectoris. These embolic particles during PCI may cause myocardial injury. However, this was difficult to confirm because it was impossible to detect embolic particles. We performed balloon angioplasty followed by stenting in 31 patients while monitoring coronary flow velocity. After PCI, we measured average peak velocity at baseline and after infusion of adenosine 5'-triphosphate to calculate coronary flow velocity reserve (CFVR) and coronary resistance index (CRI). In patients with PCI to the left coronary artery (n = 21), we calculated relative CFVR as the ratio of CFVR in the target vessel to that in the reference vessel. We measured cardiac troponin T (cTnT) the day after PCI. HITS were detected in 27 (87%) of 31 patients and the majority were observed after stenting. The total number of HITS was correlated with CRI (r = 0.36, P = 0.049) or relative CFVR (r = 0.65, P = 0.0036) but not with CFVR (r = 0.048, P = 0.82). Thirteen patients showed elevated cTnT (range, 0.05-0.31 ng/ml) and the total number of HITS was greater in those with elevated cTnT than in those without elevated cTnT (24 +/- 9 vs. 10 +/- 7, P = 0.0007). Embolic particles are frequently observed during PCI to stable plaque and the majority are liberated after stenting. There appears to be a quantitative relationship between amounts of HITS and coronary microvessel dysfunction and minor myocardial injury.

Coronary flow velocity pattern assessed by transthoracic Doppler echocardiography predicts adverse clinical events and myocardial recovery after successful primary angioplasty

Doppler guidewire studies demonstrated that specific velocity patterns in the left anterior descending coronary artery (LAD) after primary percutaneous coronary intervention (PCI) predict myocardial recovery and clinical outcome. The present study assessed whether similar results can be achieved by transthoracic Doppler echocardiography (TTDE). Coronary flow velocities of LAD were evaluated by TTDE in 35 consecutive patients with anterior acute myocardial infarction who were treated with successful primary PCI plus stenting, performed within 6 h after the onset of symptoms or within 6-12 h if there was evidence of continuing ischaemia. Coronary-flow velocity of the LAD was achieved after 12 h and within 48 h after the PCI; TTDE standard examination was repeated after 2 months of follow-up. Three patterns were found: (i) 'pattern A' with good antegrade systolic flow and slow diastolic deceleration rate (63.7%); (ii) 'pattern B' with reduced or absent systolic flow and rapid diastolic deceleration rate (9.1%); and (iii) 'pattern C' with protosystolic retrograde flow and rapid diastolic deceleration rate (27.2%). The clinical characteristics and echocardiographic data were compared: wall-motion-score-index (WMSI), ejection fraction, end-diastolic volume (EDV) after PCI (T1) and after 2 months (T2). Patients with pattern A demonstrated recovery of contractile function (WMSI-T1 1.48 + or - 0.42/WMSI-T2 1.29 + or - 0.29, P < 0.05) and better clinical outcome; patients with patterns B and C ran into ventricular remodelling (EDV-T1 89 + or - 6.3 ml/EDV-T2 123 + or - 25 ml, P = 0.002) and more early and late complications. TTDE is a reliable method to achieve coronary flow velocities in LAD after an anterior acute myocardial infarction and it could be useful to evaluate no-reflow phenomenon at bedside and thus clinical outcome.

The diastolic flow velocity-pressure gradient relation and dpv50to assess the hemodynamic significance of coronary stenoses

To evaluate the hemodynamic impact of coronary stenoses, the fractional (FFR) or coronary flow velocity reserve (CFVR) usually is measured. The combined measurement of instantaneous flow velocity and pressure gradient (v-dp relation) is rarely used in humans. We derived from the v-dp relation a new index, dp(v50) (pressure gradient at flow velocity of 50 cm/s), and compared the diagnostic performance of dp(v50), CFVR, and FFR. Before coronary angiography was performed, patients underwent noninvasive stress testing. In all coronary vessels with an intermediate or severe stenosis, the flow velocity, aortic, and distal coronary pressure were measured simultaneously with a Doppler and pressure guidewire after induction of hyperemia. After regression analysis of all middiastolic flow velocity and pressure gradient data, the dp(v50) was calculated. With the use of the results of noninvasive stress testing, the dp(v50) cutoff value was established at 22.4 mmHg. In 77 patients, 124 coronary vessels with a mean 39% (SD 19) diameter stenosis were analyzed. In 43 stenoses, ischemia was detected. We found a sensitivity, specificity, and accuracy of 56%, 86%, and 76% for CFVR; 77%, 99%, and 91% for FFR; and 95%, 95%, and 95% for dp(v50). To establish that dp(v50) is not dependent on maximal hyperemia, dp(v50) was recalculated after omission of the highest quartile of flow velocity data, showing a difference of 3%. We found that dp(v50) provided the highest sensitivity and accuracy compared with FFR and CFVR in the assessment of coronary stenoses. In contrast to CFVR and FFR, assessment of dp(v50) is not dependent on maximal hyperemia.

Coronary Vasomotor Response to Phenylephrine in Heart Transplant Patients

Coronary vasomotor responses to sympathetic stimulation vary with endothelial-layer integrity or presence of atherosclerosis. Our study objective was to assess the effects of phenylephrine-induced alpha-adrenergic stimulation on coronary vasomotion in heart transplant recipients with and without graft atherosclerosis. Intracoronary phenylephrine (alpha(1)-selective agonist) was injected in 6 control subjects, 9 recipients with angiographically normal coronary arteries and 8 recipients with mild or moderate atherosclerosis. Coronary flow velocity was measured using a Doppler guide-wire. The diameters of 3 epicardial segments of the left coronary artery and coronary blood flow and resistance were assessed at baseline, after infusion of increasing acetylcholine doses (10(-7) and 10(-6) mol/liter) and after phenylephrine (150- to 200-microg bolus). Systemic and coronary hemodynamic parameters were measured immediately after acetylcholine and 1, 3, 5, 7, 10 and 15 minutes after phenylephrine. Phenylephrine induced similar significant increases in rate pressure product in the 3 groups. Acetylcholine induced epicardial vasodilation in controls and vasoconstriction in transplant recipients. Phenylephrine induced epicardial vasodilation in controls and in angiographically normal recipients; subsequent vasoconstriction occurred in this last group. In the recipients with angiographic abnormalities, sustained vasoconstriction occurred. At peak phenylephrine effect, coronary blood flow (CBF) increased significantly (p < 0.001 vs baseline) in all 3 groups. Coronary resistance decreased in the 3 groups but the decrease was smaller in the recipients with angiographic abnormalities (p < 0.05 vs controls). In heart transplant patients, graft atherosclerosis unmasks the direct coronary vasoconstricting effects of pharmacologic alpha-adrenergic stimulation.

Value of Coronary Blood Flow Pattern as a Predictor of Functional Recovery and Short-Term Left Ventricular Remodeling After Primary Coronary Angioplasty. A Transthoracic Doppler Study

Coronary blood flow measurement using a Doppler guidewire is the most sensitive way of detecting the no-reflow phenomenon following reperfusion of a myocardial infarction (MI). New high-frequency Doppler probes enable coronary blood flow velocity to be measured noninvasively. Our aims were to study the different patterns of left anterior coronary artery blood flow observed by transthoracic Doppler echocardiography, and to describe their association with functional recovery following reperfusion of an anterior MI. The study included 57 patients with a mean age of 60 years (range 30-85 years). An abnormal coronary blo:d flow pattern was defined as one in which there was a high peak diastolic velocity and a short deceleration time (i.e., < or = 500 ms). We compared the regional contractility, ventricular volumes, and left ventricular ejection fraction (LVEF) measured after 72 hours with those measured 1 month after MI. Overall, 31 patients (54%) had a normal coronary blood flow pattern (Group 1) and 26 (46%), an abnormal pattern (Group 2). After one month, regional contractility improved in Group-1 patients, as did LVEF, from 46.8 (8.6) to 52.6 (8.8)% (P=.002). In these patients, left ventricular volumes were unchanged. In contrast, regional contractility and LVEF remained unchanged in Group-2 patients whereas ventricular volumes increased, from 55.8 (12.9) to 62.9 (16.8) ml/m2 (P=.05), and from 32.2 (9.5) to 37.1 (14.9) ml/m2 (P< .05). Coronary blood flow pattern was the most important independent predictor of left ventricular remodeling, odds ratio =6.14 (95% CI, 1.56-24.17). Transthoracic Doppler echocardiographic assessment of coronary blood flow following reperfusion of an anterior myocardial infarction can be used to identify patients with microvascular damage who are progressing towards ventricular dilatation without recovery of myocardial function.

Site of Coronary Sinus Drainage Does Not Significantly Affect Coronary Flow Reserve in Patients Long Term After Fontan Operation

This study was designed to investigate the impact of postoperative coronary sinus drainage pressure on coronary flow reserve (CFR) assessed by Doppler guidewire in patients long term after Fontan operation. Twenty-nine patients (median age, 17.4 years female, 11) at a median of 10.6 years after Fontan operation were examined with intracoronary Doppler guidewire during cardiac catheterization. Fourteen patients had coronary sinus (CS) drainage to the systemic venous atrium and 15 patients had CS drainage to the pulmonary venous atrium after Fontan operation. Median CS drainage pressure was significantly higher in systemic venous CS drainage compared to pulmonary venous CS drainage (11 vs 5 mmHg, p < 0.0001). Median CFR values for the right and left coronary artery did not differ significantly with respect to CS drainage. There was a positive correlation between coronary flow reserve and pulmonary arteriolar resistance (p < 0.05) in multivariate regression analysis. The site of coronary drainage into the systemic atrium or the pulmonary venous atrium did not significantly affect CFR. Our data do not support a surgical strategy of elective redirection of coronary sinus blood to a low-pressure compartment but support an early staged approach. The positive correlation between CFR and pulmonary resistance demands further evaluation.

Effect of Reactive Hyperemia After Coronary Recanalization on Myocardial Tissue Reperfusion by Thrombolysis In Myocardial Infarction Flow Grade in Acute Myocardial Infarction

Thrombolysis In Myocardial Infarction (TIMI) flow grade is widely used to evaluate myocardial tissue reperfusion in acute myocardial infarction (AMI), but the current grading system is incomplete. Therefore, we clarified the regulation of epicardial coronary flow velocity with the progression of microvascular dysfunction in AMI. We studied 36 patients with first anterior AMI. After intervention, we assessed TIMI flow grade and measured average peak velocity (APV) at baseline and after infusion of adenosine triphosphate (48 microg; baseline and hyperemic APVs, respectively) with a Doppler guidewire. We performed myocardial contrast echocardiography after 2 weeks to assess microvascular integrity (good reflow vs no reflow) and left ventriculography at admission and discharge (24 +/- 2 days) to measure regional wall motion (SD/chord). Patients were classified into 3 groups based on TIMI flow grade and microvascular integrity: TIMI grade 3 flow/good reflow (n = 16), TIMI grade 3 flow/no reflow (n = 12), and TIMI grade 2 flow (n = 8). Baseline APV was comparable in the patients with TIMI grade 3 flow but hyperemic APV was higher in patients with TIMI grade 3 flow/good reflow than in those with TIMI grade 3 flow/no reflow (hyperemic APV 59.3 +/- 25.8 vs 32.8 +/- 8.9 cm/s, p <0.01). All patients with TIMI grade 2 flow showed no reflow and the lowest values of baseline and hyperemic APVs. Regional wall motion at discharge was higher in patients with TIMI grade 3 flow/good reflow than in those with TIMI grade 3 flow/no reflow and TIMI grade 2 flow (-1.44 +/- 0.70, -2.69 +/- 0.31, and -2.88 +/- 0.48 SD/chord, respectively, p <0.01). In conclusion, compensatory reactive hyperemia preserves epicardial coronary flow velocity even in patients with microvascular damage, and with the progression of damage, this compensatory hyperemia can no longer preserve epicardial coronary flow velocity, and baseline APV is decreased in TIMI grade 2 flow.