Polymorphous ventricular tachycardia: a side effect of intracoronary papaverine

Clinical Efficacy of Intracoronary Papaverine After Nicorandil Administration for Safe and Optimal Fractional Flow Reserve Measurement

Fractional flow reserve (FFR) is considered the standard for assessment of the physiological significance of coronary artery stenosis. Intracoronary papaverine (PAP) is the most potent vasodilator used for the achievement of maximal hyperemia. However, its use can provoke ventricular tachycardia (VT) due to excessive QT prolongation. We evaluated the clinical efficacy and safety of the administration of PAP after nicorandil (NIC), a potassium channel opener that prevents VT, for optimal FFR measurement.A total of 127 patients with 178 stenoses were enrolled. The FFR values were measured using NIC (NIC-FFR) and PAP (PAP-FFR). We administered PAP following NIC (NIC-PAP). Changes in the FFR and electrogram parameters (baseline versus NIC versus PAP) were assessed and the incidence of arrhythmias after PAP was evaluated. In addition, we analyzed another 41 patients with 51 stenoses by assessing the FFR using PAP before NIC (PAP-NIC). After propensity score matching, the electrogram parameters between 2 groups were compared.The mean PAP-FFR was significantly lower than the mean NIC-FFR (0.82 ± 0.11 versus 0.81 ± 0.11, P < 0.05). The mean baseline-QTc, NIC-QTc, and PAP-QTc values were 425 ± 37 ms^1/2, 424 ± 41 ms^1/2, and 483 ± 54 ms^1/2, respectively. VT occurred in only 1 patient (0.6%). Although PAP induced QTc prolongation (P < 0.05), the PAP-QTc duration was significantly shorter in NIC-PAP compared to PAP-NIC (P < 0.05).The administration of PAP with NIC may induce sufficient hyperemia and prevent fatal arrhythmia through reductions in the PAP-induced QTc prolongation during FFR measurement.

Intra-procedural arrhythmia during cardiac catheterization: A systematic review of literature

BACKGROUND

Cardiac catheterization is among the most performed medical procedures in the modern era. There were sporadic reports indicating that cardiac arrhythmias are common during cardiac catheterization, and there are risks of developing serious and potentially life-threatening arrhythmias, such as sustained ventricular tachycardia (VT), ventricular fibrillation (VF) and high-grade conduction disturbances such as complete heart block (CHB), requiring immediate interventions. However, there is lack of systematic overview of these conditions.

AIM

To systematically review existing literature and gain better understanding of the incidence of cardiac arrhythmias during cardiac catheterization, and their impact on outcomes, as well as potential approaches to minimize this risk.

METHODS

We applied a combination of terms potentially used in reports describing various cardiac arrhythmias during common cardiac catheterization procedures to systematically search PubMed, EMBASE and Cochrane databases, as well as references of full-length articles.

RESULTS

During right heart catheterization (RHC), the incidence of atrial arrhythmias (premature atrial complexes, atrial fibrillation and flutter) was low (< 1%); these arrhythmias were usually transient and self-limited. RHC associated with the development of a new RBBB at a rate of 0.1%-0.3% in individuals with normal conduction system but up to 6.3% in individuals with pre-existing left bundle branch block. These patients may require temporary pacing due to transient CHB. Isolated premature ventricular complexes or non-sustained VT are common during RHC (up to 20% of cases). Sustained ventricular arrhythmias (VT and/or VF) requiring either withdrawal of catheter or cardioversion occurred infrequently (1%-1.3%). During left heart catheterizations (LHC), the incidence of ventricular arrhythmias has declined significantly over the last few decades, from 1.1% historically to 0.1% currently. The overall reported rate of VT/VF in diagnostic LHC and coronary angiography is 0.8%. The risk of VT/VF was higher during percutaneous coronary interventions for stable coronary artery disease (1.1%) and even higher for patients with acute myocardial infarctions (4.1%-4.3%). Intravenous adenosine and papaverine bolus for fractional flow reserve measurement, as well as intracoronary imaging using optical coherence tomography have been reported to induce VF. Although uncommon, LHC and coronary angiography were also reported to induce conduction disturbances including CHB.

CONCLUSION

Cardiac arrhythmias are common and potentially serious complications of cardiac catheterization procedures, and it demands constant vigilance and readiness to intervene during procedures.

Feasibility of intracoronary nicorandil for inducing hyperemia on fractional flow reserve measurement: Comparison with intracoronary papaverine

BACKGROUND

Adenosine and adenosine triphosphate (ATP) are widely used to induce hyperemia for fractional flow reserve (FFR) measurements. Caffeine attenuates their hyperemic effects, but not those of nicorandil and papaverine. No studies have systematically compared the hyperemic efficacies of nicorandil, papaverine, and ATP with and without caffeine abstention.

METHODS

FFRs were measured using nicorandil 2 mg (FFR_NC2), nicorandil 4 mg (FFR_NC4), and papaverine (FFR_PAP) in 40 patients (group 1), and using nicorandil 2 mg, ATP (FFR_ATP), ATP plus nicorandil (FFR_ATP+NC2), and papaverine in 20 patients with (group 2) and in 20 patients without caffeine abstention (group 3).

RESULTS

In group 1, FFR_NC2 and FFR_NC4 did not differ (p = 0.321) and were higher than FFR_PAP (p < 0.001 and p = 0.0026). Likewise, FFR_NC2 was higher than FFR_PAP in groups 2 (p = 0.049) and 3 (p < 0.010). In the whole group, Bland-Altman analysis showed a modest mean difference (0.015, p < 0.001) and narrow 95% limits of agreement (-0.025 and 0.056). FFR_NC2 and FFR_PAP strongly correlated (r = 0.975, p < 0.001). Compared with FFR_PAP, FFR_ATP and FFR_ATP+NC2 did not differ in group 2 (p = 1.0 and p = 0.780), but they were higher (p = 0.002 and p = 0.02) in group 3. Adjunctive nicorandil did not decline FFR further in groups 2 (p = 0.942) and 3 (p = 0.294).

CONCLUSIONS

Nicorandil 2 mg is a safe and practical alternative for patients who consume caffeine-containing products before the test or have contraindications for adenosine/ATP. Increasing the nicorandil dose to 4 mg or administering adjunctive nicorandil during ATP infusions does not offer any clinical advantages compared with administering nicorandil 2 mg alone.

Summary of Torsades de Pointes (TdP) Reports Associated with Intravenous Drug Formulations Containing the Preservative Chlorobutanol

INTRODUCTION

Drug-induced torsades de pointes (TdP) is a potentially lethal ventricular arrhythmia that is associated with drugs that prolong the QT interval on the electrocardiogram (ECG) due to their interference with the cardiac potassium current, I_KR. Intravenous (IV) formulations of methadone have been associated with TdP and contain the preservative chlorobutanol, which, like methadone, blocks I_KR. The combinations of chlorobutanol with methadone or terfenadine, another I_KR blocker, produce synergistic I_KR block.

OBJECTIVE

The aim of this study was to examine and summarize the evidence available to address the question: what other IV drug formulations contain chlorobutanol and are they associated with TdP?

METHODS

IV drug products containing the preservative chlorobutanol were identified by searching the websites DailyMed ( https://dailymed.nlm.nih.gov/dailymed/index.cfm ) and Drugs@FDA ( https://www.accessdata.fda.gov/scripts/cder/daf/ ). For each drug identified, PubMed and the FDA's Adverse Event Reporting System (FAERS) were searched for reports of TdP and/or QT prolongation and FAERS data were analyzed for disproportionality of reports.

RESULTS

The search found nine drugs (methadone, epinephrine, papaverine, oxytocin, vasopressin, testosterone, estradiol, isoniazid, and desmopressin) that contain chlorobutanol 2.5 (n = 1) or 5.0 mg/mL. All nine drugs had reports of QT prolongation or TdP reported in FAERS and all but estradiol, testosterone, desmopressin, and isoniazid had reports of QT prolongation or TdP in PubMed. Two of the nine drugs (epinephrine and methadone) had positive signals (by disproportionality analysis) for TdP in FAERS (EB₀₅ 2.88 and 23.81, respectively) and four (methadone, epinephrine, papaverine, and vasopressin) were reported in published articles as the suspect drugs in cases of TdP.

CONCLUSION

The pharmacologic profile of chlorobutanol (synergistic I_KR block) and its association with reports of TdP and QT prolongation suggest the need for a full evaluation of its cardiac safety when used as a preservative in IV drug and vitamin formulations.

Utility and Validity of Intracoronary Administration of Nicorandil Alone for the Measurement of Fractional Flow Reserve in Patients With Intermediate Coronary Stenosis

BACKGROUND

Intracoronary (IC) administration of nicorandil has been proposed as an alternative choice of hyperemic agent for fractional flow reserve (FFR) measurements. This study evaluated the utility and validity of IC nicorandil administration alone to induce maximal hyperemia.Methods and Results:Two-hundred-seven patients with coronary artery disease listed for coronary angiography with FFR were prospectively enrolled. FFR was measured after (1) IC administration of nicorandil 2 mg (ICNIC2 mg); (2) continuous intravenous (IV) adenosine triphosphatase (ATP) infusion at 150 μg/kg/min (IVATP150); (3) IV ATP infusion at 210 μg/kg/min (IVATP210); (4) IC administration of 0.5 mg nicorandil during IVATP150 (ICNIC0.5 mg+IVATP150); (5) IC administration of 1 mg nicorandil during IVATP150 (ICNIC1 mg+IVATP150); and (6) IC administration of 2 mg nicorandil during IVATP150 (ICNIC2 mg+IVATP150). The average FFR values and the rate of achieving maximum hyperemia after ICNIC2 mg, IVATP150, IVATP210, ICNIC0.5 mg+IVATP150, ICNIC1 mg+IVATP150, and ICNIC2 mg+IVATP150 were 0.85±0.08, 0.89±0.08, 0.85±0.09, 0.84±0.08, 0.83±0.08, 0.83±0.08 (P<0.01), and 92%, 54%, 91%, 96%, 99%, 99% (P<0.01), respectively. The incidence of systolic aortic pressure drop, chest discomfort, and transient atrioventricular block increased in a dose-dependent manner after IV ATP infusion, but almost no adverse effects were observed after ICNIC2 mg.

CONCLUSIONS

ICNIC2 mg produced a more pronounced hyperemia than continuous IV ATP, and might be the preferred method for assessment of FFR.

Evaluation of the risk factors for ventricular arrhythmias secondary to QT prolongation induced by papaverine injection during coronary flow reserve studies using a 4 Fr angio-catheter

Estimation of the fractional flow reserve (FFR) is considered to be an established method by which to assess stable coronary artery stenosis. Induction of maximal coronary hyperemia is important during the FFR procedure. Papaverine has been reported to increase the risk of ventricular arrhythmia (VA). The purpose of the present study was to discover predictors of papaverine-induced VAs developing during FFR measurement. A total of 213 clinically stable patients were included in the study. FFRs were determined after intracoronary papaverine administration (12 mg into the left and 8 mg into the right coronary arteries). We compared patients in whom VA did and did not develop in terms of clinical and electrocardiogram characteristics. FFR measurements were performed on 244 lesions (133 in the left anterior descending arteries, 43 in the left circumflex arteries, and 68 in the right coronary arteries). We found that the QTc interval was prolonged in all patients after papaverine administration (average post-administration QTc interval = 569 ± 89 ms; average ΔQTc interval = 144 ± 80 ms). VA developed in three patients with significantly prolonged QT intervals (average post-administration QTc interval = 639 ± 19 ms, average ΔQTc interval = 220 ± 64 ms, p < 0.02) and transitioned from torsade de pointes to ventricular fibrillation. Bradycardia (< 50 beats/min), hypokalemia (serum K < 3.5 mEp/L), and low left ventricular function (ejection fraction (EF) < 50%) were associated with VA (bradycardia, p < 0.01; hypokalemia, p < 0.01; low left ventricular function, p < 0.01). Three-vessel disease was significantly predictive of VA (p < 0.003). In the three-vessel group, the complications of low left ventricular function, hypokalemia, and bradycardia were significantly associated with VA (p < 0.045). Three-vessel disease is a predictor of the development of VA during FFR measurement performed with the aid of papaverine, especially if accompanied by one or more of the following: low left ventricular function, hypokalemia, or bradycardia.

History and Development of Coronary Flow Reserve and Fractional Flow Reserve for Clinical Applications

We discuss the historical development of clinical coronary physiology, emphasizing coronary flow reserve (CFR) and fractional flow reserve (FFR). Our analysis focuses on the clinical motivations and technologic advances that prompted and enabled the application of physiology for patient diagnosis. CFR grew from the general concepts of physiologic and coronary reserve, linking the anatomic severity of a lesion to its impact on hyperemic flow. FFR developed from existing models relating pressure measurements to the potential for flow to increase after removing a stenosis. Because pressure measurements have proved easier and more robust than flow measurements, FFR has become the dominant metric.

Papaverine-induced polymorphic ventricular tachycardia during coronary flow reserve study of patients with moderate coronary artery disease

BACKGROUND

Papaverine is useful for evaluating the functional status of a coronary artery, but it may provoke malignant ventricular arrhythmia (VA). The aim of this study was to investigate the incidence, and clinical and ECG characteristics of patients with papaverine-induced VAs. METHODS AND RESULTS: The 182 consecutive patients underwent fractional flow reserve (FFR) measurement of 277 lesions. FFR was determined after intracoronary papaverine administration by standard procedures. The clinical and ECG characteristics were compared between patients with and without ventricular tachycardia (VT: ≥3 successive premature ventricular beats (PVBs), or ventricular fibrillation (VF)). After papaverine administration, the QTc interval, QTUc interval, and T-peak to U-end interval were prolonged significantly. Single PVBs on the T-wave or U-wave type developed in 29 patients (15.9%). Polymorphic VT (torsade de pointes) occurred in 5 patients (2.8%), and of those, VF developed in 3 patients (1.7%). No clinical and baseline ECG parameters were predictors for VT or VF except for sex and administration of papaverine into the left coronary artery. Excessive prolongation of QT (or QTU), T-peak to U-end intervals and giant T-U waves were found immediately prior to the ventricular tachyarrhythmias (VTAs), which were unpredictable from the baseline data.

CONCLUSIONS

Intracoronary administration of papaverine induced fatal VTAs, although the incidence is rare. Excessive prolongation of the QT (and QTU) interval appeared prior to VTAs; however, they were unpredictable.

Comparison of intravenous adenosine and intravenous regadenoson for the measurement of pressure-derived coronary fractional flow reserve

AIMS

Defining the clinical and physiologic significance of an intermediate coronary artery stenosis is aided by measurement of fractional flow reserve (FFR). Adenosine is the most common agent used in the cardiac catheterisation laboratory for the measurement of FFR. Regadenoson, a selective adenosine receptor agonist, with fewer side effects than adenosine has been used extensively in stress testing to induce hyperaemia. We postulated that FFR measurements would be equivalent following administration of regadenoson and adenosine.

METHODS AND RESULTS

Twenty patients with an angiographic intermediate coronary artery stenosis (50% to 80%) were included in the study. FFR was measured during three minutes of intravenous (IV) adenosine infusion and for five minutes after an injection of regadenoson. The mean difference between the FFR measured by IV adenosine and IV regadenoson was 0.0040 (min -0.04, max +0.04, standard deviation [SD] 0.025). There was a strong linear correlation between the FFR measured by IV adenosine and IV regadenoson (R2 linear=0.933). The FFR at maximum hyperaemia was achieved earlier using regadenoson than adenosine (59±24.5 sec vs. 93±44.5 sec, p=0.01).

CONCLUSIONS

Regadenoson produces similar pressure-derived FFR compared to IV adenosine infusion.

Papaverine-induced polymorphic ventricular tachycardia in relation to QTU and giant T-U waves in four cases

OBJECTIVE

Papaverine is used for the evaluation of functional status of the coronary arteries but it may provoke severe ventricular tachyarrhythmias (VTAs). This study compared the clinical and ECG characteristic of patients with papaverine-induced VTAs.

MATERIALS AND METHODS

The study involved 25 patients who underwent a fractional flow reserve (FFR) study. FFR was determined as the ratio of blood pressure at the distal and the proximal site of stenosis after intracoronary papaverine administration at 12 mg into the left and 8 mg into the right coronary artery. The QT and QTU intervals were measured manually in the limb leads and in the precordial leads, respectively and corrected by the R-R interval to obtain QTc and QTUc. The clinical and ECG data were compared between the patient groups with and without VTAs.

RESULTS

After papaverine administration into the left (20), right (3) or both coronary arteries (2), the RR interval shortened, but non-significantly however, the QT interval (and QTc) and the QTU interval (and QTUc) were significantly prolonged. VTAs developed in four women: torsade de pointes in 3 followed by ventricular fibrillation and ventricular premature beats in 1 patient. After papaverine administration, QTU and QTUc were more prolonged in women than men and in patients with VTAs compared to those without. Just prior to VTAs, giant T-U waves were observed.

CONCLUSION

Intracoronary papaverine was used to determine FFR which may induce VTAs. VTAs developed only in women and they were closely related to prolongation of the QTU intervals with prominent T-U waves.

Safety of intracoronary Doppler flow measurement

BACKGROUND

With the introduction of Doppler-tipped guide wires, intracoronary Doppler flow measurement has been increasingly accepted as an additional diagnostic approach in the catheterization laboratory. However, the safety of intracoronary Doppler flow measurement has not been well-investigated. The purpose of our study was to evaluate the safety of intracoronary Doppler flow measurement using the Doppler FloWire (Cardiometrics, Mountain View, Calif).

METHODS AND RESULTS

A total of 906 patients were examined by intracoronary Doppler with a 0.014-inch or an 0.018-inch Doppler FloWire. For coronary flow reserve measurement, intracoronary injection of adenosine or papaverine was used. Of the patients studied, 77 were cardiac transplant recipients and 829 were patients who had not received a transplant, of whom 617 had undergone diagnostic coronary procedures and 212 had coronary interventions. In 27 (2.98%) of 906 patients adverse cardiac events were observed. Fifteen (1.66%) of 906 patients had severe transient bradycardia develop (asystole or second- to third-degree atrioventricular block) after intracoronary administration of adenosine, 14 of which occurred in the right coronary artery and 1 in the left anterior descending artery. Nine (0.99%) of 906 patients had coronary spasm during the passage of the Doppler wire (5 in the right coronary artery, 4 in the left anterior descending artery). Two (0.22%) of 906 patients had ventricular fibrillation during the procedure. Hypotension with bradycardia and ventricular extrasystole each occurred in 1 (0.11%) of 906 patients. The incidence of complication was significantly higher in transplant recipients than in patients who underwent either diagnostic or interventional procedures (12.99% vs 2.43% vs 0.94%, P <.001). The Doppler measurements in the right coronary artery were associated with a higher incidence of complications, especially bradycardia, compared with the left anterior descending and the left circumflex arteries (right coronary, 5.87% vs left anterior descending, 1.05% vs left circumflex, 0.17%; P <.001). All complications were cured medically.

CONCLUSION

Intracoronary Doppler flow measurement with Doppler wires and intracoronary administration of adenosine is a safe method. However, severe complications such as bradycardia and coronary spasm can occur. Attention should be paid to the examination of the right coronary artery, especially in heart transplant recipients.

Safety and optimal dose of intracoronary adenosine 5'-triphosphate for the measurement of coronary flow reserve

BACKGROUND

Adenosine 5'-triphosphate (ATP) has been demonstrated to have similar vasodilator potency and fewer hemodynamic or electrocardiographic derangements compared with papaverine in the measurement of coronary flow reserve. However, there is little data about its optimal dose and the effect on myocardial lactate metabolism.

METHODS

Under continuous monitoring of the left anterior descending coronary flow velocity with a Doppler guide wire, we investigated the changes of hemodynamics, electrocardiogram, and myocardial lactate metabolism before and after the administration of 50 microg ATP and 10 mg papaverine into the left coronary artery in 18 patients with normal coronary arteries. To determine the optimal dose of ATP for the coronary flow reserve in the left coronary artery, we measured coronary flow velocity with five incremental doses of intracoronary ATP (0.5, 5, 15, 30, and 50 microg) and 10 mg of papaverine in another seven patients.

RESULTS

In contrast to papaverine, ATP did not produce any significant changes in hemodynamics or the electrocardiogram. The increase in the coronary flow velocity of the two agents was similar. Although all patients showed lactate production after the administration of papaverine, only three patients showed lactate production after ATP (p < 0.001). The coronary flow reserve derived from > or = 215 microg of ATP was similar to that derived from papaverine. There was a significant correlation between the coronary flow reserve obtained with > or = 5 microg of ATP and that obtained with papaverine.

CONCLUSIONS

These results suggest that maximal coronary vasodilation in the left coronary artery can be safely obtained with doses > or = 15 microg of intracoronary ATP in patients with normal coronary arteries.

Measurement of myocardial fractional flow reserve during coronary angioplasty in patients with old myocardial infarction

Although myocardial fractional flow reserve (FFRmyo) has been demonstrated to be a useful index for determining functional significance of coronary stenosis, the data in previous studies was derived from a highly selected group of patients. The aim of this study was to investigate the value of FFRmyo in a more clinically relevant group of patients, especially in patients who also had resistance vessel dysfunction. We measured FFRmyo in 20 consecutive patients who had undergone elective coronary angioplasty. FFRmyo was calculated by the ratio of Pc/Pa during intracoronary adenosine 5'-triphosphate (ATP; 50 micrograms in the left coronary and 20 micrograms in the right coronary artery) induced maximal hyperemia, where Pa represents mean aortic pressure obtained by the guiding catheter and Pc represents mean distal coronary pressure measured by a 2.1 F infusion catheter. In total, 21 vessels were dilated and 14 of them were infarct-related arteries. The percent diameter stenosis significantly decreased from 80 +/- 14% to 27 +/- 17%, and the FFRmyo increased significantly from 0.46 +/- 0.18 to 0.77 +/- 0.15 after angioplasty. There was no significant differences in the FFRmyo between vessels with previous myocardial infarction and those without, after angioplasty (0.78 +/- 0.18 vs. 0.76 +/- 0.08). There was a significant correlation between the percent diameter stenosis and FFRmyo before (r = 0.83, P < 0.001) and after (r = 0.64, P < 0.01) angioplasty. In conclusion, FFRmyo significantly improved immediately after angioplasty in vessels with myocardial infarction as well as those without. These results led us to suggest the usefulness of FFRmyo in patients who had both epicardial stenosis and resistance vessel dysfunction. The significant correlation between FFRmyo and quantitative coronary arterial diameter stenosis would further support the more widespread use of FFRmyo in the clinical setting.

Intracoronary papaverine induced myocardial lactate production in patients with angiographically normal coronary arteries

Although intracoronary papaverine has been widely used for the measurement of coronary flow reserve, little is known concerning whether papaverine may produce deleterious metabolic changes in humans. We investigated the effect of papaverine on lactate metabolism in 28 patients with normal coronary arteries. We continuously monitored phasic coronary flow velocity in the proximal left anterior descending coronary artery using Doppler guidewire. We also obtained paired samples of arterial and coronary sinus blood for the measurement of lactate at control and at 1 min after administration of 10 mg of intracoronary papaverine. There were no serious side effects during papaverine infusion. Sixteen patients showed ST-T abnormalities after papaverine. The QTc interval increased from 450 +/- 42 msec to 571 +/- 58 msec (P < 0.001). Average peak velocity increased significantly (% increase: 198.5 +/- 87.8%, range: 27.8-374.1%) after papaverine. Although intracoronary papaverine produced no significant change in arterial lactate levels (8.5 +/- 4.0-8.8 +/- 5.0 mg/ml), it induced a significant increase in coronary sinus lactate levels (5.4 +/- 3.2-15.3 +/- 8.2 mg/ml, P < 0.001). Lactate extraction ratio decreased significantly (36.4 +/- 18.4--82.2 +/- 58.4%, P < 0.001), and all patients showed net lactate production (-3.9--198.0%) after papaverine. There was weak but significant correlation between lactate extraction ratio after papaverine and coronary flow reserve (R2 = 0.15, P < 0.05). There was no correlation between lactate extraction ratio and QTc interval after papaverine. The mean value of lactate extraction ratio was not different in patients with ST-T abnormalities induced by papaverine compared to those without. These results demonstrate that intracoronary papaverine induces myocardial lactate production irrespective of the degree of coronary flow reserve and electrocardiographic changes in patients with normal coronary arteries. A safer and more reliable agent is needed for the measurement of coronary flow reserve.

Comparison of intravenous adenosine to intracoronary papaverine for calculation of pressure-derived fractional flow reserve

For calculation of fractional flow reserve (FFR), simultaneous registration of both aortic pressure (Pa) and transstenotic distal coronary pressure (Pd) is necessary at steady-state maximum coronary hyperemia. The aim of the present study was to compare the maximum transstenotic gradient (delta Pmax) and pressure-derived myocardial fractional flow reserve (FFRmyo), observed during intravenous adenosine infusion, to delta Pmax and FFRmyo induced by intracoronary papaverine, which is considered to be the gold standard for induction of coronary hyperemia, but acts too short for steady-state hyperemic pressure recordings and is associated with QT-prolongation. In 24 patients with coronary stenoses of various degrees, Pa and Pd were measured simultaneously by the diagnostic catheter and a high fidelity 0.018" fiberoptic pressure monitoring guide wire, respectively. Excellent steady-state phasic intracoronary pressure recordings were obtained in all patients within 1 min after start of intravenous adenosine infusion at a rate of 140 micrograms/kg/min, and compared to delta Pmax obtained 30 sec after intracoronary administration of papaverine (12 mg LCA, 10 mg RCA). Delta Pmax was 24 +/- 15 mmHg during adenosine infusion and 24 +/- 15 mmHg after papaverine administration. Myocardial fractional flow reserve, calculated from these pressure recordings, was 0.75 +/- 0.16 and 0.75 +/- 0.15, respectively, with an individual difference of 0.02 +/- 0.01 between both values (r = 0.99). No important side effects by intravenous infusion of adenosine were observed. Thus intravenous adenosine infusion at a rate of 140 micrograms/kg/min is an excellent and safe alternative for induction of steady-state maximum coronary hyperemia and therefore is an ideal vasodilator for determination of fractional flow reserve based upon pressure recordings.

Does coronary flow reserve assessed by blood flow velocity analysis reflect absolute coronary flow reserve?

Doppler guidewire enables us to measure phasic coronary velocity and has been used for the measurement of coronary flow reserve (CFR). Although CFR is usually calculated by the quotient of peak flow velocity during papaverine infusion and flow velocity at rest, this assumption is true only if conduit vessel size is constant. To determine the accuracy of measurement of CFR using average peak velocity (APV) with Doppler guidewire, we investigated the influence of intracoronary papaverine on coronary flow velocity and coronary arterial diameter (CAD) and examined the correlation between CFR derived using APV and that derived using coronary blood flow (CBF) in 26 patients with normal coronary arteries. We measured phasic coronary flow velocity, and performed quantitative coronary angiography in the proximal left coronary artery at control and during 10 mg of intracoronary papaverine. Compared to control value, papaverine induced a significant increase in APV (% increase: 182 +/- 101%; P < 0.001). Papaverine also significantly increased CAD (16 +/- 10%; P < 0.001). Thus, CFR derived from APV was significantly lower than that derived from CBF (2.8 +/- 1.0 vs. 4.0 +/- 1.5, P < 0.001). Although there was a significantly strong positive correlation between these two methods (R2 = 0.83, P < 0.001), there was also considerable variability with regard to predicting one variable from the other. These results suggest the importance of standardizing the conditions in which coronary flow velocity is measured with regard to either controlling or measuring changes in epicardial coronary arterial diameter during changes in distal resistance vessel tone.

Impairment of coronary flow reserve in orthotopic cardiac transplant recipients with minor coronary occlusive disease

OBJECTIVE

Coronary occlusive disease is the major long-term complication after cardiac transplantation. The relation between minor angiographic abnormalities and myocardial perfusion has not been previously assessed in a large number of cardiac transplant patients.

DESIGN

Prospective study. Coronary flow reserve was measured with an intracoronary Doppler flow probe in the proximal left anterior descending coronary artery in each patient. A dose of intracoronary papaverine producing maximal vasodilation was then administered.

SETTING

A regional cardiothoracic centre and a supraregional transplant unit.

PATIENTS

Seven patients with chest pain but normal coronary anatomy (controls), and 61 cardiac transplant patients between three months and 10 years after operation (median 4.5 years). Twenty one cardiac transplant patients had angiographic evidence of minor coronary occlusive disease (mean (SD) percentage stenosis diameter 23% (6%)) in a primary or secondary coronary vessel (group 1), with 12 of these in the left anterior descending coronary artery (stenosis diameter (mean (SD) 24% (8%)). The remaining 40 transplant patients had normal coronary angiograms (group 2).

MAIN OUTCOME MEASURE

Coronary flow reserve was defined as the ratio of the peak flow velocity after papaverine to the resting flow velocity.

RESULTS

Group 1 patients had a noticeably impaired coronary flow reserve (2.6 (1.1)) compared with control patients (3.9 (0.4), p = 0.05) and, after adjusting for year after operation, compared with group 2 patients (3.8 (1.0), p < 0.001). No other variables were associated with a reduction in coronary flow reserve. Mean resting flow velocity was similar in all three groups (controls, 7.4 (4.6) cm/s; group 1, 7.5 (5.9) cm/s; and group 2, 7.3 (3.9) cm/s). Mean peak flow velocity response to papaverine was reduced in group 1 patients (18.1 (13.5) cm/s) relative to group 2 patients (27.5 (15.4) cm/s, p = 0.05) but not controls (28.4 (15.1) cm/s, p = 0.1).

CONCLUSIONS

Coronary flow reserve and the peak flow response to the coronary vascular smooth muscle relaxant papaverine are impaired in cardiac transplant patients with minor coronary occlusive disease. This disturbance of cardiac microvascular function may contribute to the late morbidity and mortality seen in cardiac transplant patients with coronary occlusive disease.

Coronary flow reserve and coronary occlusive disease

The functional effects of coronary occlusive disease (COD) in cardiac transplant patients on small-resistance coronary vessels are unclear. We investigated the changes in coronary flow reserve (CFR) in response to the non-specific smooth muscle vasodilator papaverine. A 3F Doppler probe was inserted into the left anterior descending (LAD) coronary artery in 61 patients following orthotopic heart transplantation. Studies were performed in 57 males and 4 females with a mean age of 46 years (range 20-61 years). The median time from operation was 4 years (range 3 months to 10 years). Coronary blood velocity was measured at rest (RFV) and maximum hyperaemia (PFV) produced by intracoronary papaverine. Coronary flow reserve (CFR) was defined as the ratio of PFV to RFV. Minor lesions in epicardial vessels were found in 23 transplant patients. The mean percentage diameter of the most severe lesion in the coronary tree was 23% SD 3% including 12 lesions in the LAD coronary artery itself (mean 24% SD 4%). Patients with COD had an impaired CFR (2.6 SEM 0.2) compared with normals (3.9 SEM 0.2, P = 0.0003), adjusting for year after operation. Mean resting flow velocity was similar in both groups (minor COD, 6.8 cm/s SEM 1.2; normals, 7.1 cm/s SEM 0.6), but mean peak flow velocity response to papverine was reduced (16.5 cm/s SEM 2.5 versus 27.3 cm/s SEM 2.6; P = 0.007). In the presence of minor epicardial disease, coronary flow reserve in resistance vessels was reduced due to impairment of peak flow. This demonstrates that non-endothelial-dependent coronary resistance vessel vasodilatation is abnormal and may be caused by a defect in vascular smooth muscle function.

Intravenous adenosine: continuous infusion and low dose bolus administration for determination of coronary vasodilator reserve in patients with and without coronary artery disease

To assess the use of adenosine as an alternative agent for determination of coronary vasodilator reserve, hemodynamics and coronary blood flow velocity were measured at rest and during peak hyperemic responses to continuous intravenous adenosine infusion (50, 100 and 150 micrograms/kg per min for 3 min) and intracoronary papaverine (10 mg) in 34 patients (17 without [group 1] and 17 with [group 2] significant left coronary artery disease), and in 17 patients (11 without and 6 with left coronary artery disease) after low dose (2.5 mg) intravenous bolus injection of adenosine. The maximal adenosine dose did not change mean arterial pressure (-10 +/- 14% and -6 +/- 12% for groups 1 and 2, respectively) but increased the heart rate (15 +/- 18% and 13 +/- 16, respectively). For continuous adenosine infusions, mean coronary flow velocity increased 64 +/- 104%, 122 +/- 94% and 198 +/- 59% and 15 +/- 51%, 110 +/- 95% and 109 +/- 86% in groups 1 and 2, respectively for each of the three doses. Mean coronary flow velocity increased significantly after 100 and 150 micrograms/kg of adenosine and 10 mg of intracoronary papaverine (48 +/- 25, 52 +/- 19 and 54 +/- 21 cm/s, respectively; all p less than 0.05 vs. baseline) and was significantly higher than in group 2 (37 +/- 24, 32 +/- 16, 41 +/- 23 cm/s; all p less than 0.05 vs. group 1). The coronary vasodilator reserve ratio (calculated as the ratio of hyperemic to basal mean flow velocity) for adenosine and papaverine was 2.94 +/- 1.50 and 2.94 +/- 1.00, respectively, in group 1 and was significantly and similarly reduced in group 2 (2.16 +/- 0.81 and 2.38 +/- 0.78, respectively; both p less than 0.05 vs. group 1). Low dose bolus injection of adenosine increased mean velocity equivalently to that after continuous infusion of 100 micrograms/kg, but less than after papaverine. There was a strong correlation between adenosine infusion and papaverine for both mean coronary flow velocity and coronary vasodilator reserve ratio (r2 = 0.871 and 0.325; SEE = 0.068 and 0.189, respectively; both p less than 0.0005). No patient had significant arrhythmias or prolongation of the corrected QT (QTc) interval with adenosine, but papaverine increased the QT (QTc) interval from 445 +/- 44 to 501 +/- 43 ms (p less than 0.001 vs. both maximal adenosine and baseline) and produced nonsustained ventricular tachycardia in one patient.(ABSTRACT TRUNCATED AT 400 WORDS)