Intravenous Adenosine Infusion Research Articles

Assessment of Coronary Flow Velocity Reserve by Transthoracic Doppler Echocardiography Before and After Coronary Artery Bypass Grafting

Little is known about the changes in the coronary flow velocity reserve (CFVR) of the left anterior descending artery (LAD) before and after coronary artery bypass grafting (CABG). The present study aimed to evaluate the feasibility of measuring the CFVR of the LAD using transthoracic Doppler echocardiography before and after CABG. We prospectively measured the CFVR before and after CABG in 56 patients. The flow velocity in the LAD was measured using transthoracic Doppler echocardiography both at rest and during intravenous infusion of adenosine. The CFVR was calculated as the ratio of hyperemic to the basal peak and mean diastolic flow velocities. Coronary angiography was also performed to assess graft patency after CABG in all patients. Furthermore, we compared the differences between the pre- and postoperative CFVR in patients with and without a diffusely diseased LAD (lesion length >2 cm). All grafts were angiographically patent. The postoperative peak and mean CFVR were significantly increased compared to the preoperative peak and mean CFVR (both peak and mean 2.7 ± 0.9 vs 1.5 ± 0.6, respectively; p<0.0001). The preoperative peak CFVR was significantly lower in patients with a diffusely diseased LAD than in those without a diffusely diseased LAD (1.3 ± 0.5 vs 1.6 ± 0.5, respectively; p=0.04). The postoperative peak CFVR of the 2 groups was almost identical (2.5 ± 0.6 vs 2.9 ± 1.0; p=0.07). In conclusion, assessment of the CFVR of the LAD using transthoracic Doppler echocardiography was useful after CABG for confirming graft patency.

Validation of Intravascular Ultrasound–Derived Parameters With Fractional Flow Reserve for Assessment of Coronary Stenosis Severity

We assessed optimal intravascular ultrasound (IVUS) criteria for predicting functional significance of intermediate coronary lesions. Overall, 201 patients with 236 coronary lesions underwent IVUS and invasive physiological assessment before intervention. Fractional flow reserve (FFR) was measured at maximal hyperemia induced by intravenous adenosine infusion. FFR <0.80 at maximum hyperemia was seen in 49 (21%) of the overall 236 lesions. The independent determinants of FFR were minimal lumen area (MLA; β=0.020; 95% confidence interval [CI], 0.008 to 0.031; P=0.032), plaque burden (β=-0.002; 95% CI, -0.003 to 0.001; P=0.001), lesion length with a lumen area <3.0 mm(2) (β=-0.003; 95% CI, -0.005 to -0.001; P=0.005), and left anterior descending artery location (β=-0.035; 95% CI, -0.055 to -0.016; P=0.001). The best cutoff value (with a maximal accuracy) of the MLA to predict FFR <0.80 was <2.4 mm(2), with a diagnostic accuracy of 68% (90% sensitivity, 60% specificity, and area under the curve=0.800; 95% CI, 0.742 to 0.848; P<0.001). The cutoff value of plaque burden to predict FFR <0.80 was ≥79% (69% sensitivity, 72% specificity, and area under the curve=0.756; 95% CI, 0.696 to 0.810; P<0.001). The cutoff value of lesion length with a lumen area <3.0 mm(2) was 3.1 mm (84%sensitivity, 63%specificity, and area under the curve=0.765; 95% CI, 0.706 to 0.818; P<0.001). Among 117 lesions with an MLA ≥2.4 mm(2), 112 (96%) had an FFR ≥0.80,; and all but 1 showed FFR ≥0.75. Conversely, 44 (37%) lesions with an MLA <2.4 mm(2) had an FFR <0.80. IVUS-derived MLA ≥2.4 mm(2) may be useful to exclude FFR <0.80, but poor specificity limits its value for physiological assessment of lesions with MLA <2.4 mm(2). Thus, FFR or stress tests may be necessary to accurately identify ischemia-inducible intermediate stenoses.

008 Non invasive coronary flow reserve is a powerful independent predictor of in-hospital complications in Tako-Tsubo syndrome

Several in-hospital complications (HC) could impair the clinical course of tako-tsubo syndrome (TTS). to assess the clinical and echocardiographic predictors of HC in TTS. 37 consecutive patients (pts) (mean age, 69 ± 10 years, 35 women) with a typical TTS according to the Mayo Clinic criteria underwent prospectively a comprehensive transthoracic Doppler-echocardiography including the non invasive assessment of coronary flow reserve (CFR), measured in the distal part of the left anterior descending artery using intravenous adenosine infusion, at the acute phase (within 24–48 h of symptom onset) and after recovery (1 month apart). Clinical and biochemical parameters were also assessed. HC were defined as cardiogenic shock, or thrombo-embolic event. HC occurred in 8 cases (22%). Pts with HC, compared to pts without HC, were more frequently diabetics (63% vs. 21%, p < 0.05), and had at the acute phase a more severely impaired CFR (1.8 ± 0.5 vs. 2.3 ± 0.4, p<0.01), left ventricular (LV) ejection fraction (33 ± 8% vs. 41 ± 9%,), wall motion score index, and LV systolic volume/m 2 (all, p < 0.05), Age, frequency of ECG ST-segment elevation at presentation, troponin peak, and preexisting beta-blockers use, were not significantly different in pts with and without HC (all, p = NS). The in-hospital length of stay was longer in the former group (p < 0.05). After recovery, CFR improved significantly in both groups. However, the magnitude of improvement was higher in pts with HC as compared to pts without HC (74% vs. 27%, p < 0.05) leading to final value of CFR similar in both groups (2.9 ± 0.4 vs. 3.1 ± 0.6, p = NS). In multivariate analysis, the only independent predictor of HC was acute CFR (p = 0.028). Using a ROC curve analysis a CFR < 1.9 was the best cut-off to predict HC with a sensitivity of 75% and specificity of 86%, (AUC 0.76, p < 0.01). With a mean follow-up of 24 ± 10 months, one patient died in the group of HC vs. none in the other group. CFR is an independent predictor of HC, suggesting that the impairment of the coronary microcirculation is important at the acute phase of TTS.

The Adverse Events and Hemodynamic Effects of Adenosine-Based Cardiac MRI

ObjectiveWe wanted to prospectively assess the adverse events and hemodynamic effects associated with an intravenous adenosine infusion in patients with suspected or known coronary artery disease and who were undergoing cardiac MRI.Materials and MethodsOne hundred and sixty-eight patients (64 ± 9 years) received adenosine (140 µg/kg/min) during cardiac MRI. Before and during the administration, the heart rate, systemic blood pressure, and oxygen saturation were monitored using a MRI-compatible system. We documented any signs and symptoms of potential adverse events.ResultsIn total, 47 out of 168 patients (28%) experienced adverse effects, which were mostly mild or moderate. In 13 patients (8%), the adenosine infusion was discontinued due to intolerable dyspnea or chest pain. No high grade atrioventricular block, bronchospasm or other life-threatening adverse events occurred. The hemodynamic measurements showed a significant increase in the heart rate during adenosine infusion (69.3 ± 11.7 versus 82.4 ± 13.0 beats/min, respectively; p < 0.001). A significant but clinically irrelevant increase in oxygen saturation occurred during adenosine infusion (96 ± 1.9% versus 97 ± 1.3%, respectively; p < 0.001). The blood pressure did not significantly change during adenosine infusion (systolic: 142.8 ± 24.0 versus 140.9 ± 25.7 mmHg; diastolic: 80.2 ± 12.5 mmHg versus 78.9 ± 15.6, respectively).ConclusionThis study confirms the safety of adenosine infusion during cardiac MRI. A considerable proportion of all patients will experience minor adverse effects and some patients will not tolerate adenosine infusion. However, all adverse events can be successfully managed by a radiologist. The increased heart rate during adenosine infusion highlights the need to individually adjust the settings according to the patient, e.g., the number of slices of myocardial perfusion imaging.

Efficacy and Safety of Eptifibatide vs Abciximab in ST Elevation Myocardial Infarction

performed with a pressure guidewire. Maximal coronary hyperaemia was induced by femoral intravenous adenosine infusion at 140mcg/kg/min. IMR was calculated after rapid injection of a 3mL saline bolus through the guide catheter during hyperaemia. Pv was measured from the femoral sheath and FFR and IMR recalculated using the following formulae: FFR= [Pd−Pv]/[Pa−Pv], IMR= [Pd−Pv]×Tmn. Results: Baseline and hyperaemic Pv were similar (mean±SD; 13.8± 6.0mmHg vs 13.6± 4.9mmHg; p= 0.89). FFR was lower when Pvwas included (0.83± 0.12 vs 0.80± 0.14; p< 0.01; n= 32). In six patients with borderline FFR between 0.80 and 0.85, accounting for Pv resulted in reclassification of five lesions as significant (FFR≤ 0.80). IMR was also lower when Pvwas included (16 vs 12 units; p< 0.01). Conclusion: These data suggest that Pv has a significant impact on FFR and IMR values and should be considered in decision making to revascularise patients and in research studies utilising IMR. doi:10.1016/j.hlc.2011.05.308

Randomized Flow Capacity Comparison of Skeletonized and Pedicled Left Internal Mammary Artery

The preferential harvesting technique of the internal mammary artery has been periodically debated. This randomized study evaluated the flow outcome of the skeletonized versus pedicled left internal mammary artery. Two hundred patients undergoing surgery for left anterior descending coronary artery revascularization were enrolled and randomized to pedicled (n=100) or skeletonized (n=100) harvesting. Intraoperative baseline flow and post adenosine infusion into the left ventricle, hospital outcome, echocardiographic results, and troponin I leakage were analyzed. Noninvasive periodic evaluation of flow was carried out at rest and during intravenous adenosine infusion by transthoracic Doppler ultrasound, and was stratified according to the harvesting technique. Final angiographic evaluation was performed by 64-slice multidetector computed tomography. Skeletonized left internal mammary arteries demonstrated better flow capacity at rest and during adenosine recruitment perioperatively and at all time points of follow-up. Troponin I leakage was significantly higher in the pedicled group (59 vs 42, p=0.02). Pedicled harvesting (hazard ratio [HR] 3.6, 95% confidence interval [CI] 2.5 to 6.9, p<0.001); indexed left ventricular mass greater than 150 g/m2 (HR 4.6, 95% CI 3.1 to 7.5, p<0.001); and baseline corrected thrombolysis in myocardial infarction frame count greater than 30 (HR 4.4, 95% CI, 3.8 to 7.2, p<0.001) were the most powerful multivariable predictors of graft flow reserve less than 2.0. Postoperative echocardiographic results and clinical and angiographic outcomes were comparable between the two groups. Skeletonization of the left internal mammary artery, beyond traditional proven advantages, provided significantly higher flow capacity and better graft flow reserve.

Comparison of the Extent and Severity of Myocardial Perfusion Defects Measured by CT Coronary Angiography and SPECT Myocardial Perfusion Imaging

We compared electrocardiogram-gated computed tomography (CT) myocardial perfusion imaging (MPI) based on quantification of the extent and severity of perfusion abnormalities to that measured with single-photon emission computed tomography (SPECT) MPI. Contrast-enhanced CT-MPI has been used for the identification of myocardial ischemia. We performed CT-MPI during intravenous adenosine infusion in 30 patients with perfusion abnormalities on rest/adenosine stress SPECT-MPI acquired within 60 days (18 stress-rest CT-MPI and 12 stress CT-MPI only). The extent and severity of perfusion defects on SPECT-MPI were assessed on a 5-point scale in a standard 17-segment model, and total perfusion deficit (TPD) was quantified by automated software. The extent and severity of perfusion defects on CT-MPI was visually assessed by 2 observers using the same grading scale and expressed as summed stress score and summed rest score; visually quantified TPD was given by summed stress score/(maximal score of 68) and summed rest score/68. The magnitude of perfusion abnormality on CT-MPI in regions of the myocardium was defined. On a per-segment basis, there was good agreement between CT-MPI and SPECT-MPI with a kappa of 0.71 (p < 0.0001) for detection of stress perfusion abnormalities. Automated TPD on SPECT-MPI was similar to visual TPD from CT-MPI (p = 0.65 stress TPD, and p = 0.12 ischemic TPD stress-rest) with excellent agreement (bias = -0.3 for stress TPD, and bias = 1.2 for ischemic TPD) on Bland-Altman analysis. Software-based quantification of the magnitude of stress perfusion deficit and ischemia on CT-MPI were similar to that for automated TPD measured by SPECT (p = 0.88 stress, and p = 0.48 ischemia), with minimal bias (bias = 0.6, and bias = 1.2). Stress and reversible myocardial perfusion deficit measured by CT-MPI using a visual semiquantitative approach and a visually guided software-based approach show strong similarity with SPECT-MPI, suggesting that CT-MPI-based assessment of myocardial perfusion defects may be of clinical and prognostic value.

Left ventricular remodeling in the elderly with acute anterior myocardial infarction treated with primary coronary intervention

We compared left ventricular (LV) remodeling following a first time acute anterior ST-elevation myocardial infarction (aSTEMI) treated with primary coronary intervention (pPCI) in different age groups. A total of 116 patients, 61 aged <65 and 55 aged >or=65 years, who survived after a recent aSTEMI treated with pPCI, underwent dobutamine stress-echocardiography (DSE) and non-invasive measurement of left anterior descending coronary artery flow reserve (CFR) during intravenous adenosine infusion. Baseline LV dimensions and systolic function were similar between the two groups; wall motion score indices during all DSE stages and CFR were also similar. In both groups, the LV ejection fraction was positively affected by the presence of viability in the necrosis area and by a higher CFR, but negatively influenced by viability in a remote area, an indirect sign of an extensive infarction size. This study demonstrates that PCI in the geriatric population with aSTEMI is as equally effective as in younger subjects, in terms of LV remodeling and function.

Non-invasive coronary flow reserve after successful primary angioplasty for acute anterior myocardial infarction is an independent predictor of left ventricular adverse remodelling

To assess the usefulness of non-invasive coronary flow reserve (CFR) to predict left ventricular adverse remodelling (LVR) after ST-elevation myocardial infarction (STEMI). Sixty-five consecutive patients (mean age 58 +/- 13 years, 24 women) with a first anterior STEMI, underwent prospectively CFR in the distal part of the left anterior descending artery (LAD), using intravenous adenosine infusion (0.14 mg/kg/min, within 2 min), and a standard echocardiography during the same exam, performed within 24 h after successful primary coronary angioplasty, and 6 months later, while the patients were in stable haemodynamic situation. CFR was defined as the peak hyperaemic LAD flow velocity divided by the baseline flow velocity. LV end-systolic volume (ESV) and end-diastolic volume (EDV), and LV ejection fraction (LVEF) were measured using the biplane Simpson's rule. LVR was defined as an absolute increase of ESV > or =15%. Compared with patients without LVR, patients with LVR (n = 18) had higher peak troponin T levels, wall motion score (WMS), a worse initial angiographic TIMI flow grade, and less improved electrocardiographic ST-segment resolution (all P < 0.05), and lower CFR (1.43 +/- 0.2 vs. 1.97 +/- 0.5, P < 0.01). At 6 months, patients with LVR had higher WMS, ESV, EDV, and lower LVEF compared with patients without LVR (all P < 0.01). Furthermore, acute CFR was significantly correlated to the 6-month LVEF and ESV, and to change of LVEF and ESV (all P < 0.01). In the multivariate analysis, acute CFR and initial angiographic TIMI flow grade were the independent predictors of LVR (all P < or = 0.01). Receiver-operating characteristic curve analysis demonstrated that a cut-off value of 1.7 for CFR yields a sensitivity of 100% and a specificity of 62% to predict LVR at follow-up (P < 0.001, area under the curve 0.82). Non-invasive CFR is an independent predictor of LVR after successful primary angioplasty of anterior STEMI.

Detection of haemodynamically significant coronary stenoses with k-t SENSE-accelerated Myocardial Perfusion MR Imaging at 3.0 Tesla - a comparison with fractional flow reserve

CMR k-t SENSE accelerated perfusion CMR was performed on a 3 T Philips Achieva system (saturation recovery gradient echo, repetition time/echo time 3.0 ms/1.0 ms, flip angle 15°, 5× k-t SENSE acceleration, 11 interleaved training profiles, effective acceleration 3.8, spatial resolution 1.1 × 1.1 × 10 mm3, 3 slices acquired at each RR interval). Data were acquired during adenosine hyperaemia and at rest (0.05 mmol/kg Gd-DTPA). FFR was measured in all vessels with >40% severity stenosis using a pressure sensortipped wire (Volcano®). FFR < 0.75 was considered to represent a haemodynamically significant lesion. FFR was calculated as (Pd Pv)/(Pa Pv), where Pa, Pv and Pd are simultaneous aortic, right atrial and distal coronary pressures measured during an intravenous infusion of adenosine at 140 μg/kg/min. Two experienced observers blinded to the results of the angiogram visually interpreted ischemia on CMR data as relative underperfusion of a sector within a slice or relative endocardial underperfusion compared with epicardial perfusion. The performance of visual analysis of CMR to detect flow-limiting coronary stenosis on angiography was determined. Interobserver variability was calculated using the k coefficient.

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.

Effects of adenosine on propofol consumption and postoperative analgesic efficacy of fentanyl in patients with biliary tract surfery

Objective To observe the effects of intraoperative continuous intravenous infusion of adenosine on propofol consumption and postoperative analgesic efficacy of fentanyl in patients with biliary tract surgery.Methods Forty-five ASA class Ⅰ or Ⅱ patients scheduled for biliary tract surgery were randomized into 3 groups(n=15):group A1,group A2 and group NS.Ten minutes after the induction of general anesthesia.the patients received the continuous intravenous infusion of adenosine 35 μg·kg-1· min-1,70μg·kg-1·min-1 and normal saline,respectivetly,until the end of surgery.Fentanyl 2 μand atracurium 0.6 mg·kg 1·h-1 were continuously infused throughout the surgery.The propofol was titrated to maintain a BIS target level between 40-50 and a stable hemodynamics.Postoperative analgesia was provided by patient-controlled analgesia with fentanyl.The following values were observed:①changes of mean arterial pressure(MAP)and heart rate(HR)before induction of aneathesia(T0);0(T1),15(T2)and 30(T3)minutes after incision.and at the end of surgery(T4);②propofol comsumption;③visual analogue scale(VAS)at 30 min,and 2,4,24,48 h after surgery.Results There was no significant difference in MAP and HR at To and T1 among each groups(P＞0.05).Compared with groups AI and NS,MAP and HR decreased at T2,T3,and T4 in group A2(P＜0.05).The average propofol consumption was also lower in group A2(P＜0.05).There was no significant difference in VAS at all time points and in fentanyl consumption after surgery among each groups(P＞0.05).Conclusion Continuous intravenous infusion of adenosine 70 μg·kg-1·min-1could spare propofol consumption,but do not affect VAS and postoperative fentanyl dose. Key words: Biliary tract surgery; Adenosine; Propofol; Fentanyl; Analgesia; Dose

Effect of adenosine 5′-triphosphate infusions on the nutritional status and survival of preterminal cancer patients

The aim of the study was to investigate the effect of intravenous infusions of adenosine 5'-triphosphate (ATP) on nutritional status and survival in preterminal cancer patients. Ninety-nine preterminal cancer patients (estimated life expectancy 1-6 months) with mixed tumor types were randomly allocated to receive either intravenous ATP weekly (8-10 h/week, maximum 50 microg/kg/min) for 8 weeks, or no ATP (control group). Nutritional status parameters were assessed until 8 weeks, and analyzed by repeated-measures analysis of covariance. Cox proportional hazards models were fitted to assess the effect of ATP on short-term (0-8 weeks) and long-term (0-6 months) survival. Fifty-one patients were randomized to ATP and 48 to the control group. Results showed a significant favorable effect of ATP on triceps skin fold thickness [between-group difference per 8 weeks 1.76 mm, 95% confidence interval (CI): 0.48-3.12 mm; P = 0.009] and on short-term survival [0-8 weeks hazard ratio (HR): 0.40, 95% CI: 0.17-0.95; P = 0.037]. In weight-stable patients and in lung cancer patients, long-term survival (0-6 months) was also significantly better in ATP-treated patients (weight-stable patients HR: 0.40, 95% CI: 0.19-0.83; P = 0.014; patients with lung cancer: HR: 0.35, 95% CI: 0.14-0.88; P = 0.025). In conclusion, in this population of preterminal cancer patients, ATP infusions, at the dose and schedule studied, had a favorable effect on triceps skin fold thickness and survival, especially in weight-stable patients and patients with lung cancer. Larger studies are warranted to confirm these findings and to further define the effect of ATP on tumor growth and survival.

Effects of intravenous adenosine 5′-triphosphate on intraoperative hemodynamics and postoperative pain in patients undergoing major orofacial surgery: a double-blind placebo-controlled study

We conducted a double-blind placebo-controlled study to investigate the effects of the intraoperative intravenous infusion of adenosine 5'-triphosphate (ATP) on intraoperative hemodynamics and postoperative pain in patients undergoing major orofacial surgery. Thirty patients (age, 16-42 years; 16 males/14 females) scheduled for sagittal split ramus osteotomy were assigned in a double-blind fashion to receive intraoperative intravenous infusion of ATP (n = 15) or saline (n = 15). Anesthesia was induced and maintained with propofol, fentanyl, and vecuronium. Local anesthesia was added for intraoperative analgesia. In the ATP group, ATP was infused at a rate of 160 microg.kg(-1).min(-1) throughout surgery. Postoperative pain was managed with intravenous patient-controlled analgesia (PCA) with morphine. The intensity of postoperative pain was assessed with a verbal numeric rating scale (NRS). Morphine consumption was also assessed. There were no differences in demographic, anesthetic, and surgical data between the ATP and placebo groups. Intraoperatively, ATP effectively suppressed responses of blood pressure and heart rate to painful surgical stimuli. There were no differences in postoperative NRS scores between the two groups. However, postoperative morphine consumption was significantly less in the ATP group, compared with the placebo group, throughout the 72-h postoperative observation period. Cumulative morphine consumption for 72 h postoperatively was 47% less with ATP, compared with placebo. No adverse effect of ATP was observed. Our data suggest that intraoperative ATP infusion can blunt hemodynamic responses to surgical stimuli and produce prolonged analgesia in patients undergoing major orofacial surgery.

Non-Invasive Coronary Flow Reserve After Successful Primary Angioplasty for Acute Anterior Myocardial Infarction Is an Independent Predictor of Left Ventricular Recovery and In-Hospital Cardiac Events

The prediction of left ventricular (LV) recovery and adverse cardiac events after reperfused acute myocardial infarction (AMI) is challenging. The aim of this study was to assess the usefulness of noninvasive coronary flow reserve (CFR) to predict LV recovery and in-hospital adverse cardiac events after AMI by comparison with other available tools. Fifty-five consecutive patients (mean age, 59 +/- 13 years; 33% women) with first reperfused ST-elevation anterior AMIs and sustained Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow underwent prospectively, < 24 hours after successful primary coronary angioplasty, standard echocardiography and noninvasive CFR assessment in the distal part of the left anterior descending coronary artery, using intravenous adenosine infusion, while in a stable hemodynamic situation. CFR was defined as peak hyperemic left anterior descending coronary artery flow velocity divided by baseline flow velocity. LV ejection fraction (LVEF) was measured using the biplane Simpson's rule. A no-reflow pattern was defined as diastolic deceleration time of basal diastolic coronary flow velocity < 600 ms and/or systolic flow reversal and recovery of LV function as an absolute increase of LVEF >or= 10% at 3-month follow-up. Adverse events were defined as the composite of death, recurrent AMI, and acute heart failure. In the whole population, the mean LVEF was 46 +/- 5% at baseline and 55 +/- 9% at follow-up. Patients without LV recovery had more severely impaired CFR compared with those with LV recovery (2.1 +/- 0.55 vs 1.46 +/- 0.2, P < .001), as did patients with adverse events compared with those without events (P = .01). Furthermore, CFR was significantly correlated with 3-month LVEF and regional wall motion score (both P values < .01). On multivariate analysis, CFR was an independent predictor of global and regional LV function at follow-up (both P values <or= .01) and of in-hospital cardiac events (P = .02). Receiver-operating characteristic curve analysis demonstrated that a cutoff value of 1.7 for CFR yielded sensitivity of 76% and specificity of 96% to predict LV recovery at follow-up (P < .01). Noninvasive CFR determined < 24 hours after AMI was an independent predictor of LV recovery at 3-month follow-up and of in-hospital adverse cardiac events.

Comparison of the intracoronary continuous infusion method using a microcatheter and the intravenous continuous adenosine infusion method for inducing maximal hyperemia for fractional flow reserve measurement

Inducing stable maximal coronary hyperemia is essential for measurement of fractional flow reserve (FFR). We evaluated the efficacy of the intracoronary (IC) continuous adenosine infusion method via a microcatheter for inducing maximal coronary hyperemia. In 43 patients with 44 intermediate coronary lesions, FFR was measured consecutively by IC bolus adenosine injection (48-80 microg in left coronary artery, 36-60 microg in the right coronary artery) and a standard intravenous (IV) adenosine infusion (140 microg x min(-1) x kg(-1)). After completion of the IV infusion method, the tip of an IC microcatheter (Progreat Microcatheter System, Terumo, Japan) was positioned at the coronary ostium, and FFR was measured with increasing IC continuous adenosine infusion rates from 60 to 360 microg/min via the microcatheter. Fractional flow reserve decreased with increasing IC adenosine infusion rates, and no further decrease was observed after 300 microg/min. All patients were well tolerated during the procedures. Fractional flow reserves measured by IC adenosine infusion with 180, 240, 300, and 360 microg/min were significantly lower than those by IV infusion (P < .05). Intracoronary infusion at 180, 240, 300, and 360 microg/min was able to shorten the times to induction of optimal and steady-stable hyperemia compared to IV infusion (P < .05). Functional significances were changed in 5 lesions by IC infusion at 240 to 360 microg/min but not by IV infusion. The results of this study suggest that an IC adenosine continuous infusion method via a microcatheter is safe and effective in inducing steady-state hyperemia and more potent and quicker in inducing optimal hyperemia than the standard IV infusion method.

Slow infusion of calcium channel blockers compared with intravenous adenosine in the emergency treatment of supraventricular tachycardia

IntroductionThe emergency treatment of supraventricular tachycardia (SVT) has, over the last two decades, changed from verapamil to adenosine primarily owing to documented hypotensive episodes occurring with rapid bolus infusions of the calcium channel blocker. Slow infusions of calcium channel blockers have not previously demonstrated hypotension to any significant degree. The aim of this study was to compare the efficacy and safety of bolus intravenous adenosine and slow infusion of the calcium channel blockers verapamil and diltiazem in the emergency treatment of spontaneous SVT. MethodsA prospective randomized controlled trial with one group receiving bolus intravenous adenosine 6mg followed, if conversion was not achieved, by adenosine 12mg; and the other group receiving a slow infusion of either verapamil at a rate of 1mg per minute up to a maximum dose of 20mg, or diltiazem at a rate of 2.5mg per minute up to a maximum dose of 50mg. These infusions would be stopped at time of conversion of the SVT or when the whole dose was administered. Heart rate and blood pressure was continuously monitored during drug infusion and for up to 2h post-conversion. ResultsA total of 206 patients with spontaneous SVT were analysed. Of these, 102 were administered calcium channel blockers (verapamil=48, diltiazem=54) and 104 were given adenosine. The conversion rates for the calcium channel blockers (98%) were statistically higher than the adenosine group (86.5%), p=0.002, RR 1.13, 95% CI 1.04–1.23. The initial mean change in blood pressure post-conversion in the calcium channel blocker group was −13.0/−8.1mmHg (verapamil) and −7.0/−9.4mmHg (diltiazem) and 2.6/−1.7mmHg for adenosine. Only one patient in the calcium channel group (0.98%) (95% CI 0.025–5.3) developed hypotension, and none in the adenosine group. ConclusionSlow infusion of calcium channel blockers is an alternative to adenosine in the emergency treatment of stable patients with SVT. Calcium channel blockers are safe and affordable for healthcare systems where the availability of adenosine is limited.

The Effects of Intravenous Adenosine Infusion on Intraoperative Remifentanil Requirements and Postoperative Pain in Elective Tonsillectomies Are Influenced by the Time of Day the Operation Is Performed

Background: The chronobiology of postoperative pain is an interesting topic. This study was performed to evaluate the effects of adenosine on inta-operative remifentanil requirements and on postoperative pain in patients undergoing tonsillectomies and how those effects change with changing time of day the surgery is performed. Methods: For this study, 120 patients were randomly allocated into four groups. Patients in groups B and D received adenosine at a dose of 50μg/kg/min, and those in group A and C received an equal volume of saline from 10 minutes after the induction of anesthesia until the end of surgery. Group A (saline) and B (adenosine) patients entered the operating room after 08:30 and finished before 11:00, Group C (saline) and D (adenosine) patients entered the operating room after 13:30 and finished before 16:00. We evaluated the intraoperative time-weighted mean remifentanil dose, and postoperative pain scores at 1, 6, 12, and 24 hours, and the analgesic dose required during the following 24 hours. Results: Time-weighted mean remifentanil doses during the intraoperative period and the analgesic requirement during the following 24 hours in group D was significantly lower than in the other groups. The numeric rating scale for pain at 1, and 6 hours in group D was significantly lower (P ＜ 0.01) than that of group A. There were no significant differences in side effects among groups. Conclusions: Use of intraoperative adenosine infusion provides perioperative analgesia. Postoperative pain is affected by the time of day the operation is performed. (Korean J Pain 2009; 22: 135-140)

Myocardial blood flow and adenosine A2A receptor density in endurance athletes and untrained men

Previous human studies have shown divergent results concerning the effects of exercise training on myocardial blood flow (MBF) at rest or during adenosine-induced hyperaemia in humans. We studied whether these responses are related to alterations in adenosine A2A receptor (A2AR) density in the left-ventricular (LV) myocardium, size and work output of the athlete's heart, or to fitness level. MBF at baseline and during intravenous adenosine infusion, and A2AR density at baseline were measured using positron emission tomography, and by a novel A(2A)R tracer in 10 healthy male endurance athletes (ET) and 10 healthy untrained (UT) men. Structural LV parameters were measured with echocardiography. LV mass index was 71% higher in ET than UT (193 +/- 18 g m(-2) versus 114 +/- 13 g m(-2), respectively). MBF per gram of tissue was significantly lower in the ET than UT at baseline, but this was only partly explained by reduced LV work load since MBF corrected for LV work was higher in ET than UT, as well as total MBF. The MBF during adenosine-induced hyperaemia was reduced in ET compared to UT, and the fitter the athlete was, the lower was adenosine-induced MBF. A2AR density was not different between the groups and was not coupled to resting or adenosine-mediated MBF. The novel findings of the present study show that the adaptations in the heart of highly trained endurance athletes lead to relative myocardial 'overperfusion' at rest. On the other hand hyperaemic perfusion is reduced, but is not explained by A2AR density.

Relationship between peripheral and coronary function using laser Doppler imaging and transthoracic echocardiography

Vascular dysfunction in the coronary and peripheral circulations is an early prognostic marker of future cardiovascular events. Measurements of coronary and peripheral vascular function in resistance vessels can be made, but rely on invasive procedures, which make them unsuitable for routine application. An assessment of the direct correlation between vascular responses in skin and coronary vessels has not been made previously. In 27 normal healthy subjects (18-55 years of age), we examined the relationship between peripheral and coronary vascular function. Cutaneous perfusion was measured using the non-invasive technique of laser Doppler imaging during iontophoresis of acetylcholine and sodium nitroprusside, and cutaneous vascular conductance was calculated (laser Doppler perfusion/mean arterial pressure). Coronary flow reserve was measured using transthoracic echocardiography during intravenous adenosine infusion. Mean diastolic velocities were measured at baseline and peak hyperaemic conditions from the Doppler signal recordings. CVR (coronary velocity reserve) was defined as the ratio of hyperaemic to basal mean diastolic velocities. There were significant positive correlations between CVR and cutaneous vascular conductance for acetylcholine (r=0.399, P=0.039) and sodium nitroprusside (r=0.446, P=0.020). These results support the idea that peripheral measurements of skin blood flow are representative of generalized microvascular function including that of the coronary circulation in normal healthy subjects.