Definition of flow parameters in proximal nonstenotic coronary arteries using transesophageal Doppler echocardiography

Transesophageal echocardiography (TEE) enables the visualization of proximal coronary arteries. We investigated the feasibility of coronary flow evaluation using TEE, as well as to define flow parameters found in normal proximal coronary arteries. The subgroups of patients with normal proximal segments of coronary arteries were selected from the cohort of 210 patients undergoing routine coronary angiography. The left main coronary artery (LMCA), proximal segment of left anterior descending coronary artery (LAD), left circumflex artery (LCx), and right coronary artery (RCA) were analyzed separately in 147, 64, 53, and 70 patients, respectively. Proximal coronary arteries were evaluated in the transverse plane using a 5-MHz TEE probe, and the flow in normal arteries was registered using pulsed-wave Doppler. The registration of flow with pulsed-wave Doppler was feasible in 88% of studies for the LMCA, 85% for the LAD, 58% for the LCx, and 65% for the RCA. Normal flow was laminar with distinct phasic character (diastolic predominance). Mean +/- SD values of peak coronary flow velocity were (systole/diastole) for the LMCA, 36 +/- 11/71 +/- 19 cm/sec; the LAD, 31 +/- 9/67 +/- 19 cm/sec; the LCx, 36 +/- 13/75 +/- 24 cm/sec; and the RCA, 25 +/- 8/39 +/- 12 cm/sec. Peak diastolic coronary flow velocity was most significantly correlated with heart rate. Doppler evaluation of proximal coronary flow is feasible using TEE in the majority of patients. The knowledge of normal flow values, which is different for the left and the right coronary artery, provides the background for proper interpretation of flow in diseased coronary arteries.     

The bifurcation study using 64 multislice computed tomography

Background: Various two‐stent techniques have been applied to aggressively treat bifurcation lesions as the introduction of drug‐eluting stents (DES) and the importance of the bifurcation angle and three‐dimensional (3D) structure has come to be recognized. Recent 64 multislice computed tomography (MSCT) technology provides accurate information about the 3D bifurcation geometry of the coronary arteries and with reproducibility. Objectives: The purpose of this study is to disclose the coronary bifurcation angle and 3D structure in humans and elucidate the importance of bifurcation angle for the crush technique using MSCT. Methods: Two hundred and nine patients who were suspected to have angina pectoris and underwent CT angiography using MSCT were examined. The 3D‐volume rendering (VR) image was reconstructed by two technicians and was used for the assessment of each coronary bifurcation angles. Results: The average LMT bifurcation angles (∠LMT‐LAD, ∠LMT‐LCx, ∠LAD‐LCx) were 143 ± 13°, 121 ± 21°, and 72 ± 22°, respectively, the average ∠LAD‐D was 138 ± 19°, the average ∠LCx‐OM was 134 ± 23°, the average distal RCA bifurcation angles (∠RCA‐4AV, ∠RCA‐4PD, ∠4AV‐4PD) were 152 ± 15°, 137 ± 20°, and 61 ± 21°, respectively. In addition, a percentage of steep angled bifurcation (<110°) was significantly higher in the LMT (26%) than in other bifurcations (P < 0.05). Conclusions: LMT bifurcation has been shown to have a higher rate of steep angled bifurcation in humans, it is therefore necessary to take the bifurcation angle into consideration in the case of LMT stenting. These data suggest that a bifurcation study using MSCT can clarify the 3D structure of coronary bifurcation and may provide useful information for bifurcation stenting. © 2009 Wiley‐Liss, Inc.     

Coronary Flow Velocity Reserve After Successful Balloon Angioplasty and Directional Atherectomy

Background: To ascertain whether transesophageal echocardiography (TEE) allows for measurement of coronary flow velocity "reserve" in patients with disease of the left anterior descending artery (LAD), and to establish the flow velocity response following angiographically successful angioplasty and atherectomy. Methods: Four groups of patients were studied: normal controls (n = 15) consisted of patients without obstructive coronary artery disease, a LAD stenosis group (n = 15) consisted of patients with > 70% stenosis, an LAD postangiographically successful balloon angioplasty group (n = 12), and an LAD postangiographically successful directional atherectomy group (n = 6). Two-dimensional horizontal plane TEE was used to image the proximal left coronary arterial system. Pulsed Doppler recordings were made of proximal LAD flow velocities at rest, and following an infusion of 0.56 mg/kg IV dipyridamole. Results: The peak diastolic flow velocity ratio (hyperemic flow/baseline flow) for normal controls was 3.46 ± 0.48 (mean ± standard deviation), for the LAD stenosis group was 1.35 ± 0.26, for the balloon angioplasty group was 2.08 ± 0.45, and for the directional atherectomy group was 2.10 ± 0.82. Conclusions: We conclude that: (1) it is feasible to record with TEE Doppler, flow velocity and flow reserve in normals, in obstructive coronary artery disease, and following revascularization; (2) coronary flow velocity ratio (CFVR) is decreased in patients with LAD stenosis; (3) CFVR remains subnormal in patients with angiographically successful directional atherectomy and balloon angioplasty; and (4) that flow velocity ratios following directional atherectomy were not significantly different from those following balloon angioplasty .     

Comparison of transesophageal doppler coronary flow reserve measurements with thallium-201 single-photon emission computed tomography imaging in assessment of left anterior descending artery stenoses

Background and hypothesis: Recent studies demonstrate the feasibility of coronary flow reserve measurements by transesophageal echocardiographic (TEE) Doppler recordings of coronary sinus or left anterior descending (LAD) coronary artery flow velocity for detecting stenoses of the LAD artery. This study compares coronary flow reserve measurements by Doppler TEE with thallium-201 (²⁰¹T1) single-photon emission computed tomography (SPECT) in patients with proximal single-vessel LAD stenosis. Methods: Nineteen patients with various degrees of LAD stenosis (mean area stenosis 71 ± 24%; range 24-96%) were studied. Area stenosis by quantitative coronary angiography was < 75% in 7 patients and > 75% in 12 patients. Transesophageal LAD and coronary sinus Doppler measurements were performed at baseline and after intravenous dipyridamole. Coronary flow reserve was calculated as the ratio of hyperemic to baseline average peak velocities. Predefined coronary flow reserve cut-off values of 1.8 for the coronary sinus method and of 2.0 for the LAD method were used for diagnosis of significant LAD stenosis. Results were compared with qualitative ²⁰¹T1 dipyridamole SPECT. Results: Overall predictive accuracy for diagnosis of > 75% LAD stenosis was 79% for ²⁰¹T1 SPECT, 77% for the transesophageal LAD and 79% for the transesophageal coronary sinus technique. Concordant results between ²⁰¹T1 SPECT and the LAD and coronary sinus Doppler methods were observed in 79% and 71% of patients, respectively. Conclusions: Thallium-201 SPECT and transesophageal Doppler assessment of coronary flow reserve have similar accuracy for diagnosing significant proximal LAD stenosis. Therefore, both transesophageal Doppler techniques might constitute another widely available, noninvasive method for assessment of left coronary artery disease, if disease location is proximal.     

Out-of-hospital ventricular fibrillation in patients with acute myocardial infarction: coronary angiographic determinants

OBJECTIVES: The study intended to compare the acute coronary anatomy of patients with acute myocardial infarction (AMI) complicated by out-of-hospital ventricular fibrillation (VF) versus patients with AMI without this complication. BACKGROUND: More than half of the deaths associated with AMI occur out of the hospital and within 1 h of symptom onset. The angiographic determinants of out-of-hospital VF in patients with AMI have not been investigated in detail. METHODS: Acute coronary angiographic findings of 72 consecutive patients with AMI complicated by out-of-hospital VF were compared with findings from 144 matched patients with AMI without this complication. RESULTS: Patients with an acute occlusion of the left anterior descending coronary artery (LAD) or left circumflex coronary artery (LCx) had a higher risk for out-of-hospital VF compared with patients with an acute occlusion of the right coronary artery (RCA) (odds ratio and 95% confidence interval, respectively, 4.82 [2.35 to 9.92] and 4.92 [2.34 to 10.39]). With regard to extent of coronary artery disease (CAD), the location of the culprit lesion in the coronary arteries (proximal vs. mid or distal), the flow in the infarct related artery (IRA), the presence or absence of collaterals to the IRA and chronic occlusions, there were no differences between the two groups. CONCLUSIONS: Acute myocardial infarction due to occlusion in the left coronary artery (LCA) is associated with greater risk for out-of-hospital VF compared to the RCA. The location of occlusion within LCA (LAD, LCx, proximal or distal), amount of myocardium at risk for necrosis and extent of CAD are not related to out-of-hospital VF.     

Significance of exercise-induced ST changes in leads aVR,V5, and V1. Discrimination of patients with single- or multivessel coronary artery disease

BACKGROUND: It is known that exercise-induced ST-segment elevation in lead V1 (V1-E) detects left anterior descending (LAD) stenosis. It was also postulated that ST elevation in aVR and simultaneous ST depression in V5 (aVR-E + V5-D) is a marker of ischemia due to significant stenosis of the LAD in patients with single-vessel disease. HYPOTHESIS: This study was undertaken to investigate the significance of the concomitant appearance of both electrocardiographic (ECG) ischemic markers, and of each of them alone during exercise, to detect either LAD stenosis as single-vessel coronary artery disease (CAD), or multivessel CAD involving LAD stenosis. METHODS: A total of 196 consecutive patients (152 men and 44 women, mean age 54 +/- 7 years) with at least one of these ECG markers, who underwent treadmill exercise testing with the Bruce protocol and coronary arteriography, were studied. RESULTS: Patients were divided into three groups. In Group A (83 patients with V1-E + aVR-E & V5-D), 93% of patients with single-vessel disease had significant LAD stenosis (p<0.001), whereas 75% of patients with double-vessel disease had significant stenoses of the LAD and the left circumflex (LCx) coronary arteries (p<0.01). In Group B (97 patients with aVR-E & V5-D but without V1-E), 43% of patients with single-vessel disease had significant LAD stenosis (p<0.08), whereas 85% of patients with double-vessel disease had significant stenoses of the LAD and the right coronary artery (RCA) (p<0.01). In Group C (16 patients with only V1-E), 60% of patients with single-vessel disease had significant LAD stenosis (p<0.05), whereas 75% of patients with double-vessel disease had significant LAD and LCx stenoses (p<0.05). CONCLUSIONS: The concomitant appearance of exercise-induced ST elevation in lead V1, ST elevation in lead aVR, and ST depression in lead V5, as well as the isolated appearance of ST elevation in lead V1 detect significant LAD stenosis as single-vessel disease, or significant stenoses of LAD and LCx arteries in patients with double-vessel disease, whereas the appearance of ST elevation in aVR & ST depression in V5 but without ST elevation in V1 correlates strongly with significant LAD and RCA stenoses and usually indicates double-vessel disease.     

Does Passive Smoking Impair Endothelium-Dependent Coronary Artery Dilation in Women?

Objectives. This study sought to examine whether passive smoking is associated with endothelial dysfunction in the coronary arteries.Background. Long-term exposure to cigarette smoking has been reported to suppress endothelium-dependent arterial dilation in humans. Endothelial dysfunction is an early feature of atherogenesis, and the impairment of acetylcholine (ACh)-induced coronary artery dilation indicates coronary endothelial dysfunction.Methods. We studied 38 women (40 to 60 years old) who had no known risk factors for coronary artery disease other than tobacco smoking: 11 nonsmokers who had never smoked and had never been regularly exposed to environmental tobacco smoke; 19 passive smokers with self-reported histories of exposure to environmental tobacco smoke of ≥1 h/day for ≥10 years; and 8 active smokers. We examined the response of the epicardial coronary artery diameters (proximal and distal segments of the left anterior descending [LAD] and left circumflex [LCx] coronary arteries) to the intracoronary injection of ACh into the left coronary artery by means of quantitative coronary angiography.Results. ACh significantly dilated the distal segment in nonsmokers (percent change from baseline diameter: LAD 13.7 ± 3.4%, p < 0.05; LCx 18.8 ± 2.9%, p < 0.01) but not the proximal segment (LAD 7.4 ± 3.5%; LCx 3.1 ± 5.0%). ACh significantly constricted all segments of the left coronary artery in passive smokers (LAD: proximal −20.3 ± 3.7%, p < 0.05; distal −22.3 ± 4.1%, p < 0.01; LCx: proximal −20.8 ± 3.1%, p < 0.05; distal −17.3 ± 2.9%, p < 0.01) and active smokers (LAD: proximal −14.8 ± 3.4%, p < 0.05; distal −27.2 ± 6.0%, p < 0.01; LCx: proximal −14.5 ± 6.6%, p < 0.05; distal −22.4 ± 4.0%, p < 0.01). Thus, ACh constricted most coronary arteries in both passive and active smokers and dilated the coronary arteries in nonsmokers.Conclusions. Impairment of ACh-induced coronary artery dilation, indicating coronary endothelial dysfunction, may occur diffusely in passive smokers as well as in active smokers.     

Successful retrieval of an entrapped rotablator burr using 5 Fr guiding catheter

Background : Although burr entrapment is a rare complication of the Rotablator, it is extremely difficult to retrieve a fixedly entrapped burr without surgical procedure. Case Report : An 84‐year‐old male with effort angina had heavily calcified coronary trees as well as severe stenosis in the mid LCx, and moderate stenosis in the proximal LCx, and in the LMT. We planned to perform rotational atherectomy in the LCx lesions. Using 7 Fr Q‐curve guiding catheter and Rotawire floppy, we began to ablate using 1.5‐mm burr at 200,000 rpm. Because the burr could not pass the proximal stenosis, we exchanged the wire for Rotawire extrasupport and the burr for 1.25‐mm burr, and restarted the ablation at 220,000 rpm. Although the burr could manage to pass the proximal stenosis, it had become trapped in the mid LCx lesion. Simple pull on the Rotablator, rotation of the burr, and crossing the Conquest (Confianza) wire could not retrieve it. Thus, we cut off the drive shaft and sheath of the Rotablator, inserted 5 Fr 120‐cm straight guiding catheter (Heartrail ST01; Terumo) through the remaining Rotablator system, pushed the catheter tip to the lesion around the burr as well as simultaneously pulled the Rotablator, and finally could retrieve it. Then we implanted stents in the LCx and in the LMT without difficulty. Conclusions : The 5 Fr straight guiding catheter might be useful for retrieving an entrapped burr (1.25‐mm burr). © 2011 Wiley‐Liss, Inc.     

Responses of angiographically normal human coronary arteries to intracoronary injection of acetylcholine by age and segment. Possible role of early coronary atherosclerosis

We examined the response of left coronary arteries to intracoronary injection of acetylcholine (ACh) 50 micrograms in 74 patients by measuring the diameter changes with a videodensitometric analysis system. Patients with angiographically normal coronary arteries were subdivided into a younger group of 26 patients (age, 9-29 years) and an older group of 23 patients (age, 31-68 years). In the younger group, the diameter at the distal segment of the left anterior descending artery (LAD) and at the proximal, middle, and distal segments of the left circumflex artery (LCx) increased significantly (16.7 +/- 19.3%, p less than 0.01, for LAD and 8.0 +/- 18.8%, p less than 0.05; 11.0 +/- 16.1%, p less than 0.01; and 19.8 +/- 17.5%, p less than 0.01, for LCx segments, respectively) in response to ACh. In the older group, on the other hand, the diameter at the proximal and middle segments of LAD and LCx decreased significantly (-20.8 +/- 16.9%, p less than 0.01; and -17.9 +/- 28.4%, p less than 0.01, for LAD segments and -14.6 +/- 17.4%, p less than 0.01; and -11.3 +/- 21.4%, p less than 0.05, for LCx segments, respectively). The dilator response to ACh in the younger group was significantly greater in the distal segment than in the proximal segment in both LAD and LCx (p less than 0.01 for LAD and p less than 0.05 for LCx). The constrictor response to ACh in the older group was significantly greater in the proximal than the distal segment in both LAD and LCx (p less than 0.05 for LAD and LCx, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

Classification and Atherosclerosis Distribution in Patients with Left Main Coronary Disease

Objective: The purpose of this investigation was to characterize clinical variables and angiographic distribution of coronary atherosclerosis to classify patients with de novo left main (LM) disease in a real-world population presenting for coronary angiography.
Background: Limited quantitative and angiographic published data exist that provide detailed quantitative information to classify potential target population for elective LM percutaneous coronary intervention (PCI) and guide development of dedicated LM PCI platforms.
Methods: Medical history and clinical presentation were prospectively collected on 177 consecutive patients with LM stenosis ≥50% by coronary angiography. Blinded quantitative coronary angiography (QCA) was performed on all LM stenoses to classify LM-A (ostial), LM-B (nonostial, non-bifurcation), and LM-C (bifurcation involvement). QCA was performed on the left anterior descending (LAD), left circumflex (LCx), and right coronary arteries (RCA) and branches (≥2.5 mm) to identify lesions with ≥60% stenosis or occlusion.
Results: No differences in baseline clinical history or presentation discriminated the distribution patterns of LM stenosis. QCA revealed 66% of LM stenoses were LM-C. Mean LM reference vessel diameter was 4.65 mm and average lesion length was 11.12 mm. Around 88.7% of patients had at least one lesion ≥60% in a major epicardial artery and 32.2% of patients had RCA chronic total occlusion. Right-to-left coronary collateralization was only identified in patients with obstructive stenosis in the LAD or LCx in addition to the LM stenosis.
Conclusion: Dedicated LM stent platforms may need to be developed to accommodate larger vessel size and bifurcation distributions. A majority of patients with LM stenosis will require adjunctive epicardial vessel PCI to achieve complete anatomic revascularization.     

Transthoracic, harmonic mode, contrast enhanced color Doppler echocardiography in detection of restenosis after percutaneous coronary interventions. Prospective evaluation verified by coronary angiography.

AIMS: To test the feasibility and accuracy of transthoracic, harmonic mode, contrast enhanced Doppler echocardiographic assessment of lesion severity after PCI treatment in native coronary arteries--the LAD, Cx and RCA. METHODS AND RESULTS: Prospective evaluation of 59 patients (66 arteries). Restenosis was diagnosed whenever maximal flow velocity at least doubled in comparison to the segment immediately proximal to the PCI site or when local velocity was at least 2 m/s. At 9 months of follow-up final comparison of Doppler echocardiography and coronary angiography was performed with regard to 44 arteries in 40 patients. Of LAD segments assessed, 15 were proximal and 15 middle. The figures for Cx segments were: 4 proximal and 2 mid, and for RCA 2 proximal, 5 middle and 1 distal (i.e. the posterior descending coronary artery). On final coronary angiography there were 8 restenoses--all correctly diagnosed by echocardiography. There were 2 false-positive diagnoses of restenosis. Specificity for restenosis detection was 94% and sensitivity 100%. CONCLUSION: Transthoracic echocardiography allowed for accurate stenosis assessment of principal coronary arteries after successful PTCA. Feasibility of lesion site visualization was 100% for the LAD, 75% for the Cx and 43% for the RCA. Ultrasound contrast agent improved the quality of the RCA images.     

Proximal coronary hemodynamic changes evaluated by intracardiac echocardiography during myocardial ischemia and reperfusion in a canine model

BACKGROUND: The purpose of this study was to assess whether the dynamic changes in coronary flow velocity and coronary flow velocity reserve (CFVR) by intracardiac echocardiography (ICE) within proximal coronary arteries are related to myocardial perfusion status and infarct size in a myocardial ischemia-reperfusion injury model. METHODS: In 14 dogs, left anterior descending coronary artery (LAD) was ligated for 2 hours followed by 2 hours reperfusion. Coronary flow velocity was obtained by ICE within coronary arteries at baseline, and at the end of both occlusion and reperfusion period. The CFVR was calculated as the ratio of hyperemic to resting peak diastolic velocity (PDV). Myocardial perfusion was evaluated by real time myocardial contrast echocardiography (MCE). The infarct area was detected by triphenyltetrazolium chloride (TTC) staining and expressed as the percentage of the whole left ventricular (LV) area. RESULTS: CFVR significantly decreased both in proximal LAD and left circumflex (LCx) artery at the end of occlusion, and did not recover at the end of reperfusion. However, no significant difference in flow parameters was observed between dogs with myocardial perfusion defect and those without. CFVR in LAD at the end of reperfusion did not correlate with the infarct size (r =-0.182, P = NS) either. CONCLUSIONS: Decreased CFVR detected by ICE occurs both in ischemic and in nonischemic proximal arteries during myocardial ischemia and early stage of reperfusion. This change in CFVR has poor correlation with the extent of microvascular impairment and cannot be used to predict infarct size.     

Effect of angioplasty-induced endothelial denudation compared with medial injury on regional coronary blood flow

To determine the effect of angioplasty-induced arterial injury on regional coronary blood flow, resting and postocclusion reactive hyperemic flows were measured in the left anterior descending (LAD) and circumflex (LCx) coronary arteries of 32 dogs after one of four interventions in the LAD with a balloon angioplasty catheter: group A, no injury; group B, endothelial denudation; group C, medial injury; group D, pretreatment with 325 mg of aspirin 2 hr before medial injury. Resting flows did not change in any group. In group C, hyperemic flow decreased in both the LAD and LCx by 15% to 20% (p less than .001) over 30 to 90 min, suggesting that a circulating substance changed coronary resistance. Histologic and ultrastructural studies of the LADs demonstrated an intact endothelial cell layer in group A, endothelial disruption with a few adherent platelets in group B, medial injury with a dense layer of adherent platelets in group C, and medial injury with a few adherent platelets in group D. Thus endothelial denudation results in relatively mild platelet deposition and no change in resting or hyperemic coronary blood flow. In contrast, medial injury results in relatively marked platelet deposition and a significant decrease in hyperemic flow, both of which are prevented by platelet inhibition with aspirin.     

血管内超声诊断冠状动脉临界病变的临床研究

目的：探讨血管内超声（IVUS）诊断左冠脉前降支及左主干冠状动脉临界病变的应用价值。方法：以60例冠状动脉造影（CAG）诊断的冠状动脉临界病变（包括20例左主干病例,前降支近段20例,前降支中段20例）为标准,分析血管内超声（IVUS）检查冠状动脉临界病变的价值。结果：与CAG检查比较,IVUS检查的冠状动脉平均直径狭窄率均显著升高[左主干：（65．31±7．81）％比（75．28±8．89）％,前降支近段：（66．67±8．79）％比（78．89±7．88）％,前降支中段：（71．55±6．83）％比（75．31±7．81）％,P均〈0．01]。CAG和IVUS检查在斑块钙化及斑块破裂的检出率方面无显著差异（P〉0．05）。结论：CAG不同程度地低估了冠状动脉狭窄,尤其是前降支近段,IVUS可对CAG作有效的补充,并且提高不稳定斑块的检出率,弥补了CAG的不足。     

Stenotic lesions and the bifurcation angle of coronary arteries in the young.

To determine the genesis of the high incidence of stenotic lesions of the left anterior descending artery (LAD) in the young, we have investigated the anatomical characteristics of coronary arteries in the following 3 groups; young (less than or equal to 40 yr) myocardial infarction (MI) patients with LAD lesions, young (less than or equal to 40 yr) patients without coronary stenosis and aged (greater than or equal to 60 yr) MI patients. The angle between the left main coronary artery (LMT) and the LAD in the young MI patient group (146.7 +/- 7.4 degrees) was significantly wider than those of the young normal (126.0 +/- 13.4 degrees) or the aged MI patient groups (127.1 +/- 18.6 degrees) (p less than 0.01, p less than 0.02, respectively). The angle between the LMT and the left circumflex artery (LCX), and the angle between the LAD and the LCX were not significantly different among the 3 groups. The LMT length in the young MI patient group was 18.3 +/- 4.7 mm, which was not significantly longer than those of the young normal (12.7 +/- 6.9 mm) or the aged patient groups (14.8 +/- 6.0 mm). The internal diameter ratio of the LAD and LCX was also not significantly different among the 3 groups. These results suggest that the angle between the LMT and LAD was significantly wider in young MI patients, and should be regarded as an inherited characteristic influencing the development of coronary atherosclerosis of the LAD, particularly in young MI patients.     

Comparison of the effect of the ATP-sensitive potassium channel opener YM934 with that of nitroglycerin on impaired coronary circulation in dogs

We compared the effect of an ATP-sensitive potassium channel opener, YM934, with that of nitroglycerin (NTG) on impaired coronary circulation in dogs. Coronary stenosis was produced in 7 dogs by placing a hydraulic occluder around the proximal left circumflex coronary (LCx) artery and abolishing reactive hyperemia to compromise the LCx flow. The following parameters were measured: the aortic pressure, LCx flow velocity, LCx vessel diameter, LCx peripheral pressure, and segment length in the LCx area. Subsequently, we occluded the LCx artery for 15 seconds and measured the recovery-interval (time required for the segment shortening to return to the preocclusion value). The measurements were recorded under three study conditions: (1) at baseline without LCx stenosis; (2) with LCx stenosis under NTG infusion (3 microg/Kg/min); and (3) with LCx stenosis after intravenous administration of YM934 (0.3 microg/kg). The heart rate and aortic pressure were similar under the three study conditions. Mean LCx flow velocity and segment shortening did not significantly change either. However, LCx peripheral pressure decreased after the induction of stenosis (P < 0.05) and showed no response to either NTG or YM934. YM934 administration significantly increased LCx flow in the presence of LCx stenosis, (P < 0.05), whereas NTG infusion did not. YM934 significantly shortened the recovery-interval of the segment shortening after 15-sec LCx occlusion (P < 0.05), whereas NTG did not. These findings suggest that YM934 improves coronary blood flow and prevents myocardial ischemic damage in severely impaired coronary circulation.     

Cut-off value of coronary flow velocity reserve by transthoracic Doppler echocardiography for diagnosis of significant left anterior descending artery stenosis in patients with coronary risk factors

The purpose of this study was to evaluate the adequate cut-off value of coronary flow velocity reserve (CFVR) with transthoracic Doppler echocardiography for diagnoses of significant left anterior descending (LAD) artery stenosis in a large study population with various coronary risk factors. CFVR, which has been used for evaluation of significant coronary artery stenosis, can be reduced despite angiographically normal coronary arteries in patients with various coronary risk factors. However, the adequate cut-off value of CFVR for diagnosing significant LAD stenosis has not been fully established in patients with coronary risk factors. We examined 138 consecutive patients who underwent coronary angiography. Clinical histories of coronary risk factors were determined from interviews or medical records. CFVR assessment in the LAD artery by transthoracic Doppler echocardiography was performed in all patients. Of the 138 patients, 30 had significant stenosis, and the remainder had no stenotic lesions in the LAD artery. Receiver-operating characteristic curves for detection of significant LAD stenosis showed that a cut-off value of <2.0 was extremely precise. A cut-off value <2.0 of CFVR had a sensitivity of 90%, a specificity of 93%, a positive predictive value of 77%, and a negative predictive value of 97% for the presence of significant LAD stenosis. A cut-off value <2.0 of CFVR by transthoracic Doppler echocardiography was adequate for the diagnosis of significant LAD stenosis in a population that included patients with coronary risk factors.     

Percutaneous transluminal coronary angioplasty of distal lesions: comparison of results with proximal lesions.

The results of percutaneous transluminal coronary angioplasty (PTCA) of 57 distal lesions were compared with 55 proximal lesions in 42 patients, aged 31 to 66 years (mean +/- SD: 51 +/- 9 yrs). Twenty nine (69%) had multivessel and 13 (31%) single vessel disease. The lesions classified as distal were located in left anterior descending (LAD) artery beyond the origin of second diagonal (D2), left circumflex (LCx) after the main obtuse marginal (OM) and right coronary artery (RCA) after the origin of acute marginal branch. Also included in this category were lesions in the second diagonal and obtuse marginal branches, two centimeters from their origin and stenosis in the posterior descending and posterolateral left ventricular branches of RCA. Out of 57 distal lesions 18 were 'complex' because of tandem location (5 patients), ulceration (6 lesions) and intraluminal thrombi (2 lesions). There was no significant difference in the mean luminal diameter stenosis between distal and proximal lesions, before and after PTCA. The primary success rate of angioplasty was 89.5% for the distal and 94.5% for the proximal lesions (P = NS). Inability to position the balloon across the lesion accounted for more failures in distal (3) compared to proximal (1) location. There were no major complications. Our results show that PTCA of distal lesions can be performed with a high rate of success, which is comparable to those with classical proximal lesions in the same patients.     

Dobutamine stress echocardiography as a predictor of coronary lesion severity on coronary angiography.

In order to evaluate the capacity of dobutamine stress echocardiography (stress echo) to predict the severity of atherosclerotic lesions observed on coronary angiography in patients with coronary artery disease, we performed a retrospective study at Instituto Nacional de Cardiologia and Universidade Federal Fluminense, Brazil. The health records of 40 patients who underwent both stress echo and coronary angiography within a period of less than 14 days were assessed. For the stress echo analysis, the heart was divided into 16 segments and the different types of response assessed: biphasic, ischemic, viable or unchanged. The main arteries - left anterior descending artery (LAD), left circumflex coronary artery (LCx) and right coronary artery (RCA) and their branches - were studied by coronary angiography to assess the degree of obstruction (in %), the type of lesion (A, B1, B2 or C), and the presence or absence of collateral circulation. The following results were obtained: patients showing an altered response on stress echo (ischemic) presented a higher degree of coronary obstruction as well as more complex lesions in the anterior descending artery on coronary angiography. A higher degree of obstruction was associated with more complex lesions (in LAD, LCx and RCA) and collateral circulation (in LAD and RCA). The presence of more complex lesions also correlated with collateral circulation in the LAD. Based on these results, we concluded that dobutamine stress echocardiography is a non-invasive test capable of predicting the severity of coronary lesions in patients with chronic ischemic cardiopathy.     

多排螺旋CT冠脉成像与冠脉造影对冠心病诊断的对比研究

目的初步评价多排螺旋CT（MSCT）在冠状动脉成像中的临床应用价值。方法18例疑诊冠状动脉狭窄患者行MSCT扫描,利用影像曲面重建,3D重建,了解冠状动脉病变情况,并与冠状动脉造影（CAG）对比。结果18例76支血管同时经MSCT和CAG成像。CAG发现狭窄27支,其中左前降支（LAD）病变11支,回旋支（LCA）病变3支,左主干（LMA）2支,右冠（RCA）病变9支,桥支病变2支。MSCT发现狭窄24支,其中LAD病变11支,LCA病变3支,LMA病变1支,RCA病变7支,桥支病变2支。MSCT与CAG结果相符的病变血管22支,MSCT成像的敏感性为82%（22/27）,特异性96%（47/49）。结论在控制心率的情况下MSCT可作为冠状动脉狭窄的一种无创筛选检查方法。