Intracoronary Doppler Guidewire Research Articles

Intracoronary Doppler Guidewire for Confirmation of True Lumen Position: A New Application for an Old Tool.

Intracoronary Doppler Guidewire for Confirmation of True Lumen Position: A New Application for an Old Tool.

Association between coronary microvascular function and the vasa vasorum in patients with early coronary artery disease

Background and aimsThe vasa vasorum (VV) plays a role in the initial phase of atherosclerosis, and abnormalities in microvascular function may be sensitive measures of the early development of atherosclerosis. The current study was designed to access the association between coronary microvascular function and VV density in patients undergoing cardiac catheterization. MethodsTwenty-four patients with early coronary artery disease underwent endothelium-dependent (coronary blood flow, CBF) and endothelium-independent (coronary flow velocity reserve, CFVR) coronary microvascular function testing, and optical coherence tomography (OCT) imaging of the left anterior descending coronary artery (LAD). Using an intracoronary Doppler guidewire, CBF was examined by evaluating changes in blood flow in response to acetylcholine and CFVR in response to adenosine. VV density (VV volume/vessel volume × 100, %VV) of the proximal 10 mm of the LAD was quantified by OCT. ResultsThe median values (Q1, Q3) of CFVR, % changes in CBF in response to acetylcholine, and the %VV were 2.70 (2.30, 2.90), −16.82 (−42.34, 54.52), and 2.62 (2.35, 3.35), respectively. %VV correlated inversely with CBF (r = −0.614, p = 0.001) and directly with CFVR (r = 0.423, p = 0.040). Multivariate analysis showed that only %VV was significantly correlated with CBF and the association was independent of other clinical variables, Framingham risk score, body mass index, and a family history of coronary heart disease. ConclusionsThis study demonstrates that VV density has negative correlation with endothelium-dependent microvascular function in patients with early coronary atherosclerosis. These observations link adventitial VV structure and function to microvascular dysfunction in early coronary atherosclerosis.

The waveform index of the ophthalmic artery predicts impaired coronary flow reserve

BackgroundCoronary flow reserve (CFR) can decrease with impairment in coronary microcirculation, even in the absence of epicardial conduit obstruction. Recently, the ophthalmic artery (OA), which is the first major branch of the internal carotid artery and is representative of microarterioles, has been identified using color Doppler sonography. However, the features of ultrasound waveform indices suggestive of impaired OA microcirculation and the relationships between these indices and CFR have not been elucidated. The present study aimed to assess the features of ultrasound waveform indices suggestive of impaired OA microcirculation and the relationships between these indices and CFR. Methods and resultsA total of 30 consecutive patients with a normal coronary angiogram and normal left ventricular function were studied. Patients with ≥25% stenosis of the right common or internal carotid artery were excluded. The CFR was defined as the ratio of adenosine-induced hyperemic to baseline blood flow velocity with an intracoronary Doppler guidewire. Color Doppler imaging was used to determine the blood flow velocity of the right OA, and the indices of peripheral resistance (resistance index [RI], pulsatility index [PI], and systolic mean velocity to diastolic mean velocity [Sm/Dm] ratio) were calculated. The ultrasound form showed a distinctive biphasic wave during systole followed by a monophasic wave during diastole. The velocity component in the early-systolic wave was higher than that in the mid-systolic wave or the diastolic wave (31.4±5.1 vs. 26.1±5.4 vs. 15.9±4.0cm/s, P<0.0001). The RI and PI were not related to the CFR, and the Sm/Dm ratio was negatively correlated with the CFR (β=−0.415, P=0.022). However, the relationship was attenuated by clinical variables closely associated with the Sm/Dm ratio or CFR, and hemoglobin A1c was a common mediator. The best Sm/Dm ratio cutoff for predicting an impaired CFR was 2.5 based on a receiver operating characteristic curve analysis. ConclusionsAn increase in the Sm/Dm ratio, which reflects a characteristic waveform, indicates impaired OA microcirculation. The ratio is negatively correlated with CFR, and therefore, it may be applied for the noninvasive evaluation of coronary physiology. Furthermore, hemoglobin A1c may be a common mediator for the OA and coronary microcirculation.

Use of an intracoronary Doppler guidewire for evaluation of coronary hemodynamics in the porcine model of acute hibernating myocardium during dobutamine stress tests

To determine the coronary hemodynamic characteristics of acute hibernating myocardium (AHM), evaluate the changes in coronary hemodynamics during dobutamine infusion, and investigate the mechanisms by which dobutamine stress echocardiography (DSE) detects AHM. The porcine model of acute hibernating myocardium was created in 10 animals, all of which underwent DSE with doses of 0-40 μg/kg/min. Myocardial segments abnormality was used as a DSE criterion for evaluating AHM. An intracoronary Doppler guidewire was used to measure the coronary hemodynamics; electrocardiography and systemic hemodynamics were recorded simultaneously. The ischemic regions of myocardium were reperfused, and all variables were recorded. Finally, the animals were euthanized and pathologic changes in the heart tissue were documented. There was no myocardium necrosis. There were 55 myocardial segments with abnormal DSE responses after stenosis, among which 41 segments were judged as AHM because of a biphasic response. Average peak velocity (APV) and coronary flow velocity reserve were improved during DSE. Coronary and systemic hemodynamics were increased during dobutamine infusion. There were significant differences for APV at all evaluated doses and for heart rate blood pressure product at higher doses. The difference between APV resting values and the values for peak dosage (ΔAPV) correlated with the amount of AHM during DSE. Coronary volume blood flow and coronary flow velocity reserve decreased after stenosis. ΔAPV may reflect the number of hibernating segments. The relative imbalance between blood supply and oxygen consumption in regional myocardium may be one of the mechanisms by which DSE detects AHM.

Transthoracic Doppler echocardiography to noninvasively assess coronary vasoconstrictor and dilator responses in humans

Human studies of coronary circulation are limited because of methodological issues. Recently, a noninvasive transthoracic duplex ultrasound (TTD) technique has emerged as an important tool to measure coronary blood flow velocity (CBV) in conscious humans. We employed two protocols to determine whether noninvasive "native" coronary artery velocity responses to constrictor or dilator stimuli assessed by TTD provide reliable data. In the first protocol, coronary vascular resistance (CVR = diastolic blood pressure/CBV) responses to static handgrip were examined in the left internal mammary artery (LIMA) and native left anterior descending artery (LAD) into which the graft was inserted (patient age 63 +/- 3 years). Our prior report documented increased CVR in the LIMA graft during static handgrip (Momen et al., J Appl Physiol 102: 735-739, 2007). We hypothesized that the magnitude of increases in CVR during handgrip would be similar in the LIMA graft and LAD in the same individual. Percent increases in CVR were similar in the LIMA and distal native LAD (27 +/- 4% vs. 28 +/- 6%). In the second protocol, we studied six patients (age 61 +/- 3 years) who underwent cardiac catheterization of the LAD. We compared coronary vasodilator responses to intravenous adenosine infusion (0.14 mg.kg(-1).min(-1)) obtained by intracoronary Doppler guidewire technique and TTD on separate studies. The relative increases in CBV with adenosine obtained by intracoronary Doppler guidewire and TTD were similar (62 +/- 10% vs. 65 +/- 12%). Noninvasive TTD provides reliable human coronary circulatory constrictor and dilator data.

Abstract 5252: Long-Term Administration of Thiazolidinedione Improves Vasomotion of Coronary Arteries Irrespective of Improvements in Diabetic Status for Patients Receiving an Angiotensin-II Receptor Blocker

Background: Effects of insulin sensitizing agents on coronary artery pathophysiology have marked attention, but the long-term effects remain uncertain. We previously reported clinical effects of thiazolidinedione, and adverse prognostic impacts of vasomotor dysfunction in coronary arteries. This study evaluated long-term effects of thiazolidinedione, an insulin sensitizer, on vasomotion of coronary arteries frequently affected by diabetes mellitus, in patients treated with an angiotensin-II receptor blocker, one of the best possible antiatherosclerotic therapies. Methods: Twenty-two type-2 diabetic patients treated with an angiotensin-II receptor blocker, were randomized where they received troglitazone (400mg/ day) or pioglitazone (30mg/day) (group-T), or they received therapy without thiazolidinedione for more than 1 year (group-C). We measured reactive changes in coronary blood flow (coronary flow reserve: CFR) or reactive endothelium-dependent dilatation (FMD) of coronary arteries to infusion of ATP (50 μ g) into the study (normal or minimally diseased) left coronary artery. CFR (maximal hyperemic flow-baseline flow/baseline flow) was quantified by coronary angiography and intracoronary doppler-guidewire. Changes in CFR and FMD were compared between the 2 groups. Results: All the enrolled patients manifested good compliance to the treatment and there were improvements in some of metabolic variables in group-T (n=11). CFR increased in group-T (p=0.027) but not in group-C (p=0.102). FMD also increased in group-T (p&lt;0.001), while it remained unchanged in group-C (p=0.768). Changes of CFR or FMD did not correlate to those of HbA1c (CFR: r=0.19, p=0.66, FMD: r=0.15, p=0.80). Conclusion: This study suggests that long-term thiazolidinedione use improves vasomotion of coronary arteries irrespective of glucose metabolic status, which may have beneficial potentials for management of coronary artery disease with type-2 diabetes mellitus.

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 …

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.

Relationship Between Coronary Flow and Viability in Patients With Myocardial Infarction Submitted to Revascularization With Stent. Assessment by Doppler Guidewire

Introduction and objectives. Intracoronary Doppler guidewire measurement provides information about the state of the myocardial microcirculation. Our aim was to assess the relationship between the pattern of coronary flow and myocardial viability. Patients and method. The study included 19 patients who had had a recent myocardial infarction (< 1 month), who underwent percutaneous revascularization of the responsible vessel, and who agreed to angiographic follow-up. Patients were divided into two groups according to the extent of the akinetic area observed at follow-up responsible (149 [40] days) in the myocardial region supplied by the responsible artery: one group (n=11) had preserved regional contractility (i.e., an akinetic area less than 30%); the other group (n=8) had impaired regional contractility (i.e., an akinetic area equal to or greater than 30%). Coronary flow in the artery was responsible assessed after revascularization and at follow-up using the Doppler guidewire method. After revascularization, patients with preserved regional contractility had a higher diastolic deceleration half-time than those with impaired regional contractility (628 [188] ms vs 376 [131] ms, P=.02). At follow-up, the difference in coronary flow between the groups had disappeared. Patients in whom regional contractility was preserved demonstrated a significant increase in coronary flow reserve at follow-up (1,8 [0,5] vs 2,3 [0,5], P=.01). After timely revascularization (within one month) of the vessel responsible for a myocardial infarction, the pattern of coronary flow observed in patients with viable myocardium differed from that in those with non-viable myocardium. The differences disappeared during follow-up.

Comparison of transthoracic Doppler echocardiography to intracoronary Doppler guidewire measurements for assessment of coronary flow reserve in the left anterior descending artery for detection of restenosis after coronary angioplasty

Transthoracic Doppler echocardiography (TDE) has been described as a feasible and accurate technique to noninvasively assess coronary flow reserve (CFR) in the left anterior descending artery (LAD). This study was designed to evaluate whether serial assessment of CFR in the LAD using TDE allows detection of restenosis after previously performed angioplasty. Thirty-three consecutive patients with single-vessel coronary artery disease of the LAD scheduled for angioplasty underwent assessment of coronary flow velocity at rest and during adenosine-induced hyperemia in the distal LAD using high-frequency TDE. CFR was calculated as the ratio of hyperemic to basal systolic/diastolic mean velocity. Investigations were performed before and immediately after angioplasty, and at the time of control angiography after 3 months. CFR results by TDE were compared with intracoronary Doppler guide wire measurements. Adequate pulse-wave Doppler signals to measure CFR were obtained in 30 patients (91%) using TDE. There was close correlation between echocardiographically and intracoronary derived CFR results (r = 0.80, 0.79, and 0.87 before angioplasty, early after, and at 3- month control angiography, respectively; p <0.001). Using a cut-off value of CFR ≤2.0 to identify significant coronary artery disease, TDE detected LAD restenosis with a sensitivity of 89% and specificity of 90%. Thus, high-frequency TDE is a feasible technique to noninvasively assess CFR in the LAD with results closely corresponding to invasive measurements. Defining a cut-off value of CFR ≤2.0, the technique has the potential to reliably detect LAD stenosis after coronary intervention.

Normal coronary flow reserve after arterial switch operation for transposition of the great arteries: an intracoronary doppler guidewire study

Normal coronary flow reserve after arterial switch operation for transposition of the great arteries: an intracoronary doppler guidewire study

Noninvasive assessment of coronary flow velocity and coronary flow velocity reserve in the right coronary artery by transthoracic doppler echocardiography: Comparison with intracoronary doppler guidewire

The aim of this study was to evaluate whether coronary flow velocity (CFV) and coronary flow velocity reserve (CFVR) in the posterior descending right coronary artery can be reliably measured by transthoracic Doppler echocardiography (TTDE). In 17 patients, CFV in the posterior descending right coronary artery was measured with TTDE at the time of Doppler guidewire examination. CFV was measured by both methods at baseline and under hyperemic conditions. TTDE data were obtained for 12 patients. CFV and CFVR by TTDE show a good correlation with those obtained by the Doppler guidewire method (average diastolic peak velocity: r = 0.98, y = 0.85x + 5.26; diastolic peak velocity: r = 0.97, y = 0.94x + 3.39; CFVR: r = 0.97, y = 0.87x + 0.56). CFV and CFVR in the posterior descending right coronary artery obtained noninvasively by TTDE accurately reflect these values obtained by the invasive Doppler guidewire method. (J Am Soc Echocardiogr 2002;15:1074-9.)

Coronary Endothelium-Dependent and Independent Vasomotor Responses in Patients With Hypertrophic Cardiomyopathy

It is well known that coronary flow reserve (CFR) is decreased in patients with hypertrophic cardiomyopathy (HCM), but it is unclear whether coronary endothelial function is impaired. Coronary endothelial function and CFR in the coronary macro- and microcirculation was evaluated in 14 patients with HCM and 11 control subjects. Acetylcholine (ACh), bradykinin (BK) and papaverine were infused into the left coronary artery. Coronary cross-sectional area was determined by quantitative coronary angiography and coronary blood flow (CBF) was determined by the product of the coronary cross-sectional area and CBF velocity measured by an intracoronary Doppler guidewire. Acetylcholine at 100 microg induced diffuse coronary spasms of the left anterior descending coronary arteries in 3 of the patients with HCM. The changes in the diameter of the left anterior descending coronary artery and the increases in CBF induced by BK (0.2, 0.6, and 2.0 microg/min) did not differ between the 2 groups. CFR was lower in the HCM group than in the control group (p<0.01). Moreover, the ratio of BK-induced CBF increase to papaverine-induced CBF increase was comparable between the 2 groups. Endothelium-dependent vasodilation of the epicardial and resistance coronary arteries induced by BK was preserved despite the decreased CFR in patients with HCM.

Measuring maximal percent area stenosis poststent placement with intracoronary Doppler and the continuity equation and correlation with intracoronary ultrasound and angiography

Quantitative coronary angiography (QCA) and intracoronary ultrasound (ICUS) are methods for anatomic assessment of stent deployment. Intracoronary Doppler is primarily a method for the physiologic assessment of coronary stenoses. It correlates well with traditional noninvasive measurements of lesion significance. Intracoronary Doppler was used for the anatomic assessment of de novo coronary artery stenosis with variable success; however, its use for anatomic assessment of adequate stent deployment is unavailable. A rapid, automated software program was developed based on a modified continuity equation to calculate the maximal in-stent percent area stenosis by comparing the maximal in-stent velocity to an average reference velocity (proximal and distal). This study was designed to compare the Doppler method of an anatomic assessment with QCA and ICUS in 15 patients. Physiologic success of stent deployment was determined by the distal coronary flow reserve to 24 to 36 μg of intracoronary adenosine. Following successful stent deployment, distal coronary flow reserve increased significantly from a baseline of 1.6 ± 0.5 to 2.9 ±1.1. There was a significant correlation between the maximal in-stent percent area stenosis as measured by Doppler and both QCA (r = 0.78, p <0.01) and ICUS (r = 0.84, p <0.01). This study demonstrates that maximal in-stent percent area stenosis can be measured by intracoronary Doppler and a novel software program. The intracoronary Doppler guidewire method can assess the adequacy of stent deployment using both anatomic and physiologic principles and may supplement other quantitative methodologies.

Hemodynamic and Coronary Effects of the Endothelin Antagonist Bosentan in Patients With Coronary Artery Disease

Endothelin is a potent endothelium-derived vasoconstrictor peptide with proliferative properties. Elevated levels of the peptide occur in coronary artery disease; however, its pathophysiological role as a regulator of coronary tone and structure is uncertain. Endothelin-receptor antagonists are specific tools to clarify this issue and might be useful in the treatment of coronary artery disease. In a double-blind, placebo-controlled randomized study, we investigated the effects of the ETA/ETB endothelin-receptor antagonist bosentan or placebo on systemic and coronary hemodynamics in 28 patients with angiographically documented stable coronary artery disease by quantitative coronary angiography and an intracoronary Doppler guidewire. Bosentan 200 mg IV decreased systolic blood pressure (P<0. 05), whereas heart rate increased slightly (P<0.05). Coronary diameter increased, particularly in vessels with no or mild angiographic changes (P<0.01). Glycerol trinitrate did not further dilate these segments, whereas coronary diameter increased significantly after nitrate in the placebo group. The increase in coronary diameter after bosentan correlated inversely with plasma LDL-cholesterol levels (P<0.01) in both stenotic and angiographically normal coronary segments. Coronary flow velocity did not change. Bosentan was well tolerated. Endogenous endothelin exerts a vasoconstrictor tone in epicardial coronary arteries of patients with coronary artery disease, as evidenced by the vasodilation exerted by the combined ETA/ETB endothelin-receptor antagonist bosentan under acute conditions. Bosentan can safely be given to these patients. Hence, further long-term studies are necessary to determine the therapeutic potential of endothelin-receptor antagonists in patients with coronary artery disease.

Comparison of Intracoronary Doppler Guide Wire and Transesophageal Echocardiography in Measurement of flow Velocity and Coronary flow Reserve in the Left Anterior Descending Coronary Artery

Comparison of Intracoronary Doppler Guide Wire and Transesophageal Echocardiography in Measurement of flow Velocity and Coronary flow Reserve in the Left Anterior Descending Coronary Artery

Coronary Arterial Flow-Velocity Dynamics in Children With Angiographically Normal Coronary Arteries

There have been few reports about coronary hemodynamics in children during the process of growth. In the present study, to assess the characteristics of coronary flow dynamics in children, we examined the phasic coronary flow-velocity (CFV) patterns at rest and during peak hyperemic responses in children with angiographically normal coronary arteries. Spectral Doppler phasic coronary flow velocity was recorded with a 0.018-in intracoronary Doppler guidewire at rest and during peak responses after intracoronary bolus injection of ATP in 30 patients with Kawasaki's disease (age, 8.2 +/- 5.1 years; 24 boys and 6 girls) without angiographic coronary lesions. Average peak velocity (APV), maximum peak velocity (MPV), and diastolic-to-systolic velocity ratio (DSVR) were evaluated in the left anterior descending coronary artery (LAD), left circumflex artery (LCx), and right coronary artery (RCA). Coronary vasodilator reserve (coronary flow reserve [CFR]) was calculated as the ratio of ATP-induced hyperemic to baseline APV. Flow-velocity parameters in RCA were significantly lower than those in the LAD and LCx in both proximal and distal portions. Although the distal LCx had significantly lower values of APV and MPV than did the proximal LCx, there was no significant difference between the proximal and distal portions of the LAD and RCA for APV and MPV. All three coronary vessels showed a diastolic dominant flow pattern in each segment. This coronary flow pattern was less marked in the RCA than in the LCA. All three coronary vessels showed a significant increase in APV and a significantly decrease in DSVR after ATP administration. CFR was significantly lower in the LCx than in the LAD or RCA (P < .01: 1.93 +/- 0.34 in LCx versus 2.32 +/- 0.42 in LAD and 2.37 +/- 0.44 in RCA). From the view of aging, it was revealed that APV values in three vessels were higher in the younger group than in the older group. CFR values in the LAD and LCx were significantly lower in the younger group than in the older group (P < .001 in LAD: 2.01 +/- 0.28 in the younger versus 2.53 +/- 0.37 in the older; P < .01 in LCx: 1.61 +/- 0.15 in the younger versus 2.06 +/- 0.31 in the older). In addition, intracoronary injection of ATP did not increase the absolute angiographic coronary luminal diameter. With the use of an intracoronary Doppler guidewire, we demonstrated that there are some characteristic findings in CFV dynamics in childhood. These physiological characteristics in CFV dynamics that occur with aging and occur in each vessel must be taken into consideration in the study of the coronary circulation in children.

786-2 Coronary Flow Reserve vs Transleslonal Velocity Gradient by Doppler Guidewire in Assessing Intermediate Coronary Stenoses

Intracoronary Doppler guidewire measures of coronary flow reserve (CFR) and translesional velocity gradients (TVG) have been used to determine the physiologic significance of intermediate coronary lesions (40–70%). In many patients with intermediate stenoses CFR and TVG values are discordant, raising the possibility that CFR is diminished due to microvascular rather than epicardial disease. In 13 patients with an intermediate coronary lesion, we used an intracoronary Doppler guidewire to record baseline coronaryflowvelocity proximal and distal to each lesion, thus defining TVG. Peak hyperemic velocity was then recorded distally after an intracoronary bolus of adenosine to obtain CFR. All patients had decreased CFR (mean = 1.4 ± 0.3; normal ≥2.0) but trivial TVG (mean = 1.3 ± 0.3; normal &lt;1.7). Each patient had a reversible perfusion defect on stress SPECT 201 TI imaging and subsequently underwent PTCA. These patients were asked to return at 6 months for a repeat stress SPECT201 TI test. Two patients had restenosis prior to repeat stress testing. The remaining 11 patients had their baseline and 6 month post-PTCA scans analyzed. Region of Interest201 TI Ouantitation (counts as % of normal) Pre-PTCA Stress 77 ± 2.5 Post-PTCA Stress 89 ± 3.0 * Delay 93 ± 3.0 * Delay 93 ± 4.0 P(ANOVA) &lt; 0.0001 * p &lt; 0.05 vs Pre-PTCA Stress All 11 patients demonstrated qualitative normalization of SPECT 201 TI scans at 6 month follow-up. Ouantitative polar mapping and region of interest analysis confirmed the improvement in perfusion. Therefore, blunted CFR was related to a physiologically significant intermediate stenosis rather than a microvascular cause. It appears that CFR is a more reliable indicator of lesion significance than TVG.

1028-67 Coronary Flow Reserve and Stress SPECT 201TI in Intermediate Saphenous Vein Graft Lesions

Coronary flow reserve (CFR) has become a useful means for determining the physiologic significance of native coronary lesions. While CFR normalizes following coronary bypass surgery, the utility of CFR in the evaluation of saphenous vein graft (SVG) lesions has not been defined. Therefore, we examined the correlation between CFR and stress SPECT 201TI results in 13 patients with SVG lesions of intermediate severity (40– 80% stenosis). In each patient, the SVG supplied normal myocardium, and the bypassed vessel was at least half the diameter of the SVG. Coronary flow velocity was recorded at baseline and following adenosine-induced hyperemia using an 0.014′ intracoronary Doppler guidewire. Patients subsequently underwent exercise SPECT 201TI imaging and were classified by stress 2.201TI results as being normal or having a reversible defect. Twelve SVGs without stenoses supplying normal myocardium served as controls. Control SVGs had a CFR of 2.6 ± 0.4, (range 2.0–3.6),Empty CellNormographic 201TI (n = 7)Reversible 201TI (n = 6)p valueCFR2.8 ± 061.5 ± 0.40.0001Stenosis (%)61 ± 964 ± 13NSMLD(mm)1.5 ± 0.31.3 ± 0.5NSMLD = minimal luminal diameter MLD = minimal luminal diameter Quantitative angiographic sperity did not distinguish patients with evidence of ischemia by stress SPECT 201TI imaging. CFR, however, was significantly reduced in patients with reversible 2 1TI defects. Using a normal CFR of ≥2.0, the sensitivity, specificity and predictive accuracy of CFR compared to stress 201TI results were 83%, 100% and 92%, respectively. Thus, Doppler guidewire measures of CFR correlate with stress SPECT 201TI results and may be useful in determining the physiologic significance of intermediate SVG lesions.

Alterations of coronary collateral blood flow velocity during intraaortic balloon pumping

Controversy exists regarding the ability of intraaortic balloon pumping to increase coronary blood flow either directly or through collateral perfusion. 1–4 In patients, directly measured coronary flow velocity by intracoronary Doppler guidewire technique distal to severe coronary stenoses is minimal and unaffected by intraaortic balloon pumping. 5 After coronary angioplasty, intraaortic balloon pumping increases both proximal and, more importantly, distal coronary artery flow velocity. 5 Whether collateral flow is altered during intraaortic balloon pumping has not been adequately studied in humans because of a lack of quantitative means to assess collateral blood flow. 6 With the use of a Doppler-tipped angioplasty guidewire, retrograde collateral flow velocity can be directly measured, and thus quantitate the effects of interventions altering collateral blood flow responses. 7 While performing angioplasty with the Doppler guidewire, we quantitated intracoronary collateral blood flow alterations during intraaortic balloon pumping in 3 patients: 2 with acute myocardial infarction and 1 with unstable angina. These observations using flow velocity techniques to evaluate perturbations of collateral flow are the first physiologic demonstrations in patients of one of the unique hypothesized beneficial antiischemic mechanisms of intraaortic balloon pumping.