Coronary Pressure Measurement Research Articles

Coronary Pressure Measurement After Stenting Predicts Adverse Events at Follow-Up

Coronary stenting is associated with a restenosis rate of 15% to 20% at 6-month follow-up, despite optimum angiographic stent implantation. In this multicenter registry, we investigated the relation between optimum physiological stent implantation as assessed by poststent fractional flow reserve (FFR) and outcome at 6 months. In 750 patients, coronary pressure measurement at maximum hyperemia was performed after angiographically apparently satisfactory stent implantation. Poststenting FFR was calculated and related to major adverse events (including need for repeat target vessel revascularization) at 6 months. In 76 patients (10.2%), at least 1 adverse event occurred. Five patients died, 19 experienced myocardial infarction, and 52 underwent at least 1 repeat target vessel revascularization. By multivariate analysis, FFR immediately after stenting was the most significant independent variable related to all types of events. In 36% of the patients, FFR normalized (>0.95), and event rate was 4.9% in that group. In 32% of the patients, poststent FFR was between 0.90 and 0.95, and event rate was 6.2%. In 32% of patients, poststent FFR was <0.90, and event rate was 20.3%. In 6% of the patients, FFR was <0.80, and event rate was 29.5% (P<0.001). FFR after stenting is a strong independent predictor of outcome at 6 months.

Can thrombolytic therapy provide beneficial effects additional to epicardial coronary artery recanalization? A study based on coronary pressure measurement.

Collaterals provide significant blood supply to the myocardium at risk and the presence of a preserved and adequate collateral network may limit microvascular damage during the occlusion of an epicardial coronary artery. The aim of this study was to evaluate whether thrombolytic therapy (TT) may produce beneficial effects at the level of microvascular circulation in addition to epicardial coronary artery recanalization by using quantitative intracoronary pressure measurement techniques in patients with recent acute myocardial infarction (AMI). Thirty-six patients who presented with AMI and had preinfarction angina pectoris, more than 60% stenosis and thrombolysis in myocardial infarction (TIMI) grade II flow in the infarct-related artery and who underwent a stent implantation procedure within 10 days of AMI were included in this study. Seventeen of 36 patients had received TT (group 1) and 19 had not received TT due to presence of contraindications or late admission (group 2). Quantitative coronary angiography, TIMI frame count (TFC) assessment and intracoronary pressure measurements were performed before and after stent implantation for all patients. Myocardial fractional flow reserve (FFRmyo) was calculated as the ratio of mean distal coronary pressure to mean aortic pressure. During total occlusion with balloon inflation, distal pressure was recorded as coronary wedge pressure (CWP). Collateral flow index (CFI) was determined by the ratio of simultaneously measured CWP to mean aortic pressure. There were no differences between the two groups with respect to mean per cent stenosis and mean FFRmyo both before and after stent implantation. The mean CWP (25.1 +/- 8.6 mmHg compared with 17.2 +/- 6.2 mmHg, P < 0.01) and CFI (0.24 +/- 0.10 compared with 0.16 +/- 0.11, P < 0.01) were significantly higher and mean post-stent corrected TFC (18.8 +/- 3.7 compared with 22.4 +/- 3.1, P < 0.01) was significantly faster in the group of patients who had received TT compared to those who had not. We concluded that destruction degree of collateral circulation and distal microvasculature is lower in patients who had received TT, compared to patients who could not be treated with TT. Besides protective effect on collateral vessels, TT provides even more reperfusion and less destruction of the microvasculature.

Preconditioning effect during coronary angioplasty in patients with stable angina pectoris.

To determine whether collateral recruitment is involved in the preconditioning effect on the electrocardiogram, chest symptoms, and lactate metabolism during coronary angioplasty in patients with stable angina pectoris. Sixteen patients with stable angina pectoris underwent three consecutive 2-min balloon inflations 5-min apart. The greatest ST elevation (deltaSTmax), the sum of ST elevations in all leads (sum(ST)), and QT dispersion (QTd) were measured at the end of each balloon inflation. Chest pain score was evaluated on a scale ranging from no pain (0) to the most severe pain (10). Lactate extraction ratio (LER) was determined by simultaneous blood sampling from the aorta and the coronary sinus. Collateral flow index (CFI) was derived from simultaneous measurements of mean aortic pressure and coronary wedge pressure obtained from a pressure guidewire during balloon inflation. Significant decreases were noted in deltaSTmax (3.3+/-2.1 vs. 3.0+/-1.9 vs. 2.6+/-1.8 mm, p<0.01), sum(ST) (9.7+/-7.2 vs. 8.5+/-6.1 vs. 6.9+/-5.3 mm, p<0.01), QTd (55.3+/-13.8 vs. 46.9+/-9.0 vs. 42.5+/-10.0 ms, p<0.01), and chest pain score (4.3+/-3.1 vs. 2.8+/-2.6 vs. 1.4+/-1.5, p<0.01) during the three sequential balloon inflations. LER significantly increased (-55.5+/-47.8 vs. -36.7+/-34.3 vs. -19.6+/-26.2%, p<0.01), indicating decreased lactate production. No significant difference was observed in CFI (0.16+/-0.10 vs. 0.15+/-0.10 vs. 0.15+/-0.10). Repeated balloon inflations during coronary angioplasty elicited a preconditioning effect on ST-segment shift, QT dispersion, chest pain, and lactate production that does not involve collateral recruitment.

Frequency distribution of collateral flow and factors influencing collateral channel development: Functional collateral channel measurement in 450 patients with coronary artery disease

OBJECTIVESWe sought to determine the pathogenetic predictors of collateral channels in a large cohort of patients with coronary artery disease (CAD).BACKGROUNDThe frequency distribution of collateral flow in patients with CAD is unknown. Only small qualitative studies have investigated which factors influence the development of collateral channels.METHODSIn 450 patients with one- to three-vessel CAD undergoing percutaneous transluminal coronary angioplasty (PTCA), collateral flow was measured. A collateral flow index (CFI; no unit) expressing collateral flow relative to normal anterograde flow was determined using coronary wedge pressure or Doppler measurements through sensor-tipped PTCA guide wires. Frequency distribution analysis of CFI and univariate and multivariate analyses of 32 factors, including gender, age, patient history, cardiovascular risk factors, medication and coronary angiographic data, were performed.RESULTSTwo-thirds of the patients had a CFI <0.25 and ∼40% of patients had a CFI <0.15, but only ∼10% of the patients had a recruitable CFI ≥0.4. By univariate analysis, the following were predictors of CFI ≥0.25: high levels of high-density lipoprotein cholesterol, the absence of previous non–Q-wave myocardial infarction, angina pectoris during an exercise test, angiographic indicators of severe CAD and the left circumflex or right coronary artery as the collateral-receiving vessel. Percent diameter stenosis of the lesion undergoing PTCA was the only independent predictor of a high CFI.CONCLUSIONSThis large clinical study of patients with CAD in whom collateral flow was quantitatively assessed reveals that two-thirds of the patients do not have enough collateral flow to prevent myocardial ischemia during coronary occlusion, and that coronary lesion severity is the only independent pathogenetic variable related to collateral flow.

Curriculum in interventional cardiology: Coronary pressure and flow measurements in the cardiac catheterization laboratory

Curriculum in interventional cardiology: Coronary pressure and flow measurements in the cardiac catheterization laboratory

Curriculum in interventional cardiology: coronary pressure and flow measurements in the cardiac catheterization laboratory.

Curriculum in interventional cardiology: coronary pressure and flow measurements in the cardiac catheterization laboratory.

PTCA versus bypass surgery in patients with multivessel disease: A tailored approach based on coronary pressure measurement Cees-Joost Botman, G. Jan-Willem Bech, Bernard De Bruyne, Hans Bonnier, Jozef Bartunek, Jacques Koolen, Rolf Michels, Nico Pijls. Catharina Hospital, Eindhoven, The Netherlands, Cardiovascular Center, Aalst, Belgium

PTCA versus bypass surgery in patients with multivessel disease: A tailored approach based on coronary pressure measurement Cees-Joost Botman, G. Jan-Willem Bech, Bernard De Bruyne, Hans Bonnier, Jozef Bartunek, Jacques Koolen, Rolf Michels, Nico Pijls. Catharina Hospital, Eindhoven, The Netherlands, Cardiovascular Center, Aalst, Belgium

Coronary pressure and FFR predict long-term outcome after PTCA.

Although coronary stents have been the most important improvement in percutaneous coronary interventions in the last 10 years, it is well known to interventionalists that many patients after percutaneous transluminal coronary angioplasty (PTCA) have a favourable outcome without stenting. Coronary angiography, however, is not sensitive enough to identify those particular patients and it has been suggested that a combination of angiographic and functional criteria would be more suitable to distinguish patients with a low restenosis chance after plain balloon angioplasty. In the present study, the authors investigated the value of coronary pressure measurement for conditional stenting in 85 patients. It was demonstrated that in patients in whom a high fractional flow reserve (FFR) was present (> 0.90), the incidence of coronary events at two-year follow-up was almost three times lower than in those patients with an FFR below 0.90. Such high FFRs could be obtained in approximately 45% of all patients. In an additional group of patients, it was demonstrated by intravascular ultrasound (IVUS) studies that the mechanism of a high FFR after plain balloon angioplasty is most likely the result of a larger lumen compared with patients with a suboptimal FFR. This means that, in patients in whom both the angiographic and the functional result after PTCA is optimal, a restenosis rate is achieved similar to that achieved by stenting. Obviously, in such patients, additional stenting and a number of problems in the long-term possibly related to stenting can be avoided. Therefore, coronary angiography and coronary pressure measurement have a complementary value in the evaluation of PTCA results and such information can be easily obtained by using a pressure wire instead of a regular guidewire.

Coronary pressure measurement to assess the hemodynamic significance of serial stenoses within one coronary artery: validation in humans.

When several stenoses are present within 1 coronary artery, the hemodynamic significance of each stenosis is influenced by the presence of the other(s), and the calculation of coronary and fractional flow reserve (CFR and FFR) for each individual stenosis is confounded. Recently, we developed and experimentally validated a method to determine the true FFR of each stenosis as it would be after the removal of the other stenosis; the true FFR can be reliably predicted by coronary pressures measured before treatment at specific locations within the coronary artery using equations accounting for stenosis interaction. The aim of the present study was to test the validity of these equations in humans. In this study of 32 patients with 2 serial stenoses in 1 coronary artery, relevant pressures were measured before the intervention, after the treatment of 1 stenosis, and after the treatment of both stenoses. The true FFR of each stenosis (FFR(true)) was directly measured after the elimination of the other stenosis and compared with the value predicted (FFR(pred)) from the initial pressure measurements before treatment. Although the hyperemic gradient across 1 stenosis increased significantly (from 10+/-7 to 19+/-11 mm Hg after treatment of the other stenosis), FFR(pred) was close to FFR(true) in all patients (0.78+/-0.12 versus 0.78+/-0.11 mm Hg; r=0.92; Delta%=4+/-0%). Without accounting for stenosis interaction, the value of FFR for each stenosis would have been significantly overestimated (0.85+/-0.08; P:<0.01). Coronary pressure measurements made by a pressure wire at maximum hyperemia provide a simple, practical method for assessing the individual hemodynamic significance of multiple stenoses within the same artery.

Erratum: Practice and potential pitfalls of coronary pressure measurement

Catheterization and Cardiovascular InterventionsVolume 50, Issue 1 p. 157-157 ErratumFree Access Erratum: Practice and potential pitfalls of coronary pressure measurement NHJ Pijls, NHJ PijlsSearch for more papers by this authorMJ Kern, MJ KernSearch for more papers by this authorPG Yock, PG YockSearch for more papers by this authorB De Bruyne, B De BruyneSearch for more papers by this author NHJ Pijls, NHJ PijlsSearch for more papers by this authorMJ Kern, MJ KernSearch for more papers by this authorPG Yock, PG YockSearch for more papers by this authorB De Bruyne, B De BruyneSearch for more papers by this author First published: 12 May 2000 https://doi.org/10.1002/(SICI)1522-726X(200005)50:1<157::AID-CCD30>3.0.CO;2-UCitations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume50, Issue1May 2000Pages 157-157 SCAI Member Sign in RelatedInformation

Erratum: Practice and potential pitfalls of coronary pressure measurement

Catheterization and Cardiovascular InterventionsVolume 50, Issue 1 p. 157-157 ErratumFree Access Erratum: Practice and potential pitfalls of coronary pressure measurement NHJ Pijls, NHJ PijlsSearch for more papers by this authorMJ Kern, MJ KernSearch for more papers by this authorPG Yock, PG YockSearch for more papers by this authorB De Bruyne, B De BruyneSearch for more papers by this author NHJ Pijls, NHJ PijlsSearch for more papers by this authorMJ Kern, MJ KernSearch for more papers by this authorPG Yock, PG YockSearch for more papers by this authorB De Bruyne, B De BruyneSearch for more papers by this author First published: 12 May 2000 https://doi.org/10.1002/(SICI)1522-726X(200005)50:1<157::AID-CCD30>3.0.CO;2-UCitations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume50, Issue1May 2000Pages 157-157 SCAI Member Sign in RelatedInformation

Practice and potential pitfalls of coronary pressure measurement.

Guidewire-based coronary pressure measurement has emerged over the last years as a promising approach in the invasive assessment of coronary artery disease. It enables calculation of fractional flow reserve (FFR) which closely relates distal coronary pressure to myocardial blood flow during maximal arteriolar vasodilation. Coronary pressure measurement and FFR provide important information, both for decision making in diagnostic angiography and for monitoring and evaluating coronary interventions. In this review, the practical set-up of coronary pressure measurement in the catheterization laboratory is discussed step-by-step, special attention is given to potential pitfalls and how to avoid them, and the interpretation of coronary pressure measurement in a variety of pathologic conditions is clarified. Cathet. Cardiovasc. Intervent. 49:1-16, 2000.

Practice and potential pitfalls of coronary pressure measurement

Practice and potential pitfalls of coronary pressure measurement

Fractional Flow Reserve: Who Needs the Pressure Wire?

Recently, the interest in coronary pressure measurements has been revived thanks to technical innovations (the development of pressure‐measuring angioplasty guidewire) and theoretical progress (the concept of pressure derived fractional flow reserve). Fractional flow reserve (FFR) is the ratio of maximal flow in the myocardial region depending on a stenosis to maximal flow in that same region if the stenosis were absent. With the development of pressure guidewires, fractional flow reserve can be calculated rapidly and safely in the diagnostic and interventional setting. It has been shown that pressure derived FFR can be used as a surrogate for a stress test for on‐line clinical decision making in the catheterization laboratory. Values &lt; 0.75 are most often associated with exercise‐inducible myocardial ischemia, while values &gt; 0.75 exclude objective signs of ischemia during exercise. The accuracy of FFR for that purpose is approximately 95% and higher than that of any single noninvasive test taken alone. Of note, it has been shown that prognosis is favorable in patients in whom a planned angioplasty was deferred on the basis of a myocardial fractional flow reserve &gt; 0.75. After regular balloon angioplasty, the combination of a good angiographic result and a FFR &gt; 0.90 is associated with an event rate during a 2‐year follow‐up, which is similar to that after stenting. After stent implantation, FFR should normalize. A FFR &lt; 0.94 after stent implantation appears to be as accurate as intravascular ultrasound (IVUS) to detect stent malposition. Thus, pressure derived FFR is a well‐validated index of stenosis severity that has evolved from a physiological index to a clinical tool.

Usefulness of fractional flow reserve to predict clinical outcome after balloon angioplasty.

After regular coronary balloon angioplasty, it would be helpful to identify those patients who have a low cardiac event rate. Coronary angiography alone is not sensitive enough for that purpose, but it has been suggested that the combination of optimal angiographic and optimal functional results indicates a low restenosis chance. Pressure-derived myocardial fractional flow reserve (FFR) is an index of the functional severity of the residual epicardial lesion and could be useful for that purpose. In 60 consecutive patients with single-vessel disease, balloon angioplasty was performed by use of a pressure instead of a regular guide wire. Both quantitative coronary angiography (QCA) and measurement of FFR were performed 15 minutes after the procedure. A successful angioplasty result, defined as a residual diameter stenosis (DS) <50%, was achieved in 58 patients. In these patients, DS and FFR, measured 15 minutes after PTCA, were analyzed in relation to clinical outcome. In those 26 patients with both optimal angiographic (residual DS by QCA </=35%) and optimal functional (FFR >/=0.90) results, event-free survival rates at 6, 12, and 24 months were 92+/-5%, 92+/-5%, and 88+/-6%, respectively, versus 72+/-8%, 69+/-8%, and 59+/-9%, respectively, in the remaining 32 patients in whom the angiographic or functional result or both were suboptimal (P=0.047, P=0.028, and P=0.014, respectively). In patients with a residual DS </=35% and FFR >/=0.90, clinical outcome up to 2 years is excellent. Therefore, there is a complementary value of coronary angiography and coronary pressure measurement in the evaluation of PTCA result.

Long-Term Follow-Up After Deferral of Percutaneous Transluminal Coronary Angioplasty of Intermediate Stenosis on the Basis of Coronary Pressure Measurement

Objectives. This study sought to determine the safety of deferral of percutaneous transluminal coronary angioplasty (PTCA) of angiographically intermediate but functionally nonsignificant stenosis, as assessed by coronary pressure measurement and myocardial fractional flow reserve (FFRmyo).Background. Decision making in patients with chest pain and intermediate coronary stenosis remains difficult. In these cases it is unclear whether the risk of an intervention and the potentially subsequent restenosis outweigh the future risk of an event if the lesion remains untreated. FFRmyois a lesion-specific functional index of epicardial stenosis severity that accurately distinguishes stenoses associated with inducible ischemia.Methods. Retrospective analysis and follow-up was performed in 100 consecutive patients referred to our centers for PTCA of an intermediate stenosis but in whom the planned intervention was deferred on the basis of an FFRmyo≥0.75.Results. During a follow-up period of 18 ± 13 months (mean ± SD, range 3 to 42), two patients died of noncardiac causes. Ninety patients remained free of any coronary events, and their average Canadian Cardiovascular Society class decreased from 2.0 ± 1.2 at baseline to 0.7 ± 0.9 at follow-up (p < 0.0001). A coronary event occurred in eight patients and was target-vessel related in four.Conclusions. In patients with chest pain referred for PTCA of an intermediate stenosis, deferral of the intervention on the basis of an FFRmyo≥0.75 is safe and is associated with a much lower clinical event rate than if the procedure had been performed as initially planned in these patients.

Fluorescence Intravital Microscopy of the Coronary Microvasculature

Much of our knowledge of coronary blood flow regulation is based on global blood flow measurements or from studies of large epicardial coronary arteries. Those studies which have examined the coronary microcirculation, have often considered it as a single homogeneous vascular bed. However, regulation of coronary microvascular resistance is not distributed uniformly, but varies across different segments of the vasculature. Under normal conditions, a major portion of coronary vascular resistance is controlled by the coronary arterioles.Studies of these vessels in vivo are difficult, due to problems associated with cardiac and ventilatory motion. To eliminate these problems, we have utilized a technique of fluorescent stroboscopic epi-illumination. Dogs (4-12 kg) were anesthetized with sodium pentobarbital, intubated, and ventilated with room air. A 24 gauge catheter was placed in the proximal left circumflex coronary artery for measurements of coronary artery pressure and administration of drugs. Following these procedures, the animal was ventilated on a high frequency jet ventilator synchronized to the cardiac cycle.

Clinical assessment of functional stenosis severity: Use of coronary pressure measurements for the decision to bypass a lesion

In the selection of patients eligible for minimally invasive coronary artery bypass grafting (MICABG), knowledge about the pathophysiologic significance of individual coronary stenoses is important. Only if the lesion amenable to MICABG can be identified as the culprit lesion, and other lesions can be demonstrated not to be responsible for reversible ischemia, will MICABG be an appropriate procedure. By simultaneous measurement of mean aortic pressure and transstenotic coronary pressure, a pathophysiologic index can be obtained that specifically indicates the influence of an epicardial coronary stenosis on maximum achievable blood flow of the supplied myocardial territory. This index is called myocardial fractional flow reserve (FFR(myo)). Myocardial fractional flow reserve is a reliable, lesion-specific index for determining whether a particular stenosis is responsible for reversible myocardial ischemia. If FFR(myo) is less than 0.75, revascularization is indicated, whereas if FFR(myo) is greater than 0.75, revascularization usually is not warranted. Moreover, in contrast to classic coronary flow or flow velocity reserve, FFR(myo) is independent of changes in heart rate, blood pressure, and contractility, and also accounts for the contribution of collaterals. Pressure-derived FFR(myo) is an accurate pathophysiologic index for reliable identification of functionally significant epicardial lesions and can be obtained easily and quickly during routine cardiac catheterization. Therefore, FFR(myo) facilitates clinical decision-making with respect to the appropriateness of MICABG.

Evaluation of a pressure-recording guidewire in patients with coronary arterial disease.

The accuracy and feasibility of coronary arterial pressure measurements with a 0.018-in. pressure-recording guidewire (PRGW) was evaluated in patients. Transstenotic pressure gradients were measured with the PRGW and a guiding catheter, at baseline and during coronary vasodilatation. Proximal intracoronary pressure was measured with both systems before and after gradient measurements. Zero pressure was measured with the PRGW before and after intracoronary use. The average of all proximal intracoronary PRGW readings were close to guiding catheter values, but there were substantial individual deviations. Average change in proximal deviation before and after gradient measurements was -1 mm Hg, standard deviation (S.D.) 7.6, range -16 to 15. Errors in zero pressure measurements after intracoronary use (average 2.8 mm Hg, S.D. 8.8, range -9 to 35) were much greater than before use (average 0.1 mm Hg, S.D. 1.4, range -4 to 3, P < 0.001). The PRGW was successfully introduced through an 8F guiding catheter and positioned across the stenosis in 21 of 26 attempts (81%). Intracoronary advancement of the PRGW through a double-lumen multifunctional probing catheter was successful in all nine attempts. In conclusion, errors in PRGW-measurements caused uncertainty in gradient interpretation. However, we found the wire useful in several cases, particularly for exclusion of hemodynamically significant lesions. The steerability of the wire is inferior to ordinary guidewires, but it can be advanced to a distal intracoronary position through an over-the-wire catheter.

The effects of high dose N G-nitro- l-arginine-methyl ester on myocardial blood flow and left ventricular function in dogs

Purpose: Nitric oxide (NO) synthase inhibition has been reported to cause elevation in mean arterial pressure (MAP) and a decrease in cardiac index (Cl), the cause of which is not completely understood. It has been shown that increased concentrations of NO synthase inhibitors cause a further drop in cardiac output without a corresponding increase in arterial pressure, prompting the conclusion that NO inhibition results in direct myocardial depression. However, myocardial ischemia was not completely ruled out as a cause for myocardial dysfunction in these studies. The purpose of this study was to examine the effects of 30 mg/kg of the NO synthase inhibitor N G-nitro- l-arginine-methyl ester (L-NAME) to those of 300 mg/kg and assess the effects on coronary ischemia and myocardial function. Materials and Methods: Eight anesthetized dogs underwent median sternotomy and pericardiectomy. L-NAME 30 mg/kg was administered and the effects were recorded at 5, 15, and 30 minutes. Thereafter, 300 mg/kg was administered and the effects were observed for 5, 15, and 30 minutes. We measured MAP, heart rate (HR), Cl, left ventricle (LV) end systolic and diastolic pressures, the first derivative of LV pressure (dP/dt), left anterior descending artery blood flow, regional LV contraction, gas tensions, and lactates. A coronary sinus catheter allowed for measurements of coronary sinus pressure, lactate, and gas tensions. Stroke volume, percent myocardial shortening (dL/dt) myocardial oxygen consumption, and net lactate myocardial production were calculated. Results: Whereas 30 mg/kg had minimal effects on coronary blood flow and LV function, 300 mg/kg resulted in profound hypotension, drop in Cl, and acidocis. Conclusions: L-NAME at 30 mg/kg caused a rise in MAP and systemic vascular resistance; however, it had no effect on ventricular function. High dose NO synthase inhibition causes myocardial depression not related to increased afterload, coronary vasoconstriction, or myocardial ischemia.