Coronary microvascular function in patients with angina with no obstructive coronary artery disease-What factors affect it clinically or angiographically?

Background

In the clinical setting, we have often experienced patients with angina with no obstructive coronary artery disease (ANOCA), and it has been proposed that the presence of coronary microvascular dysfunction (CMD) play a pivotal role in the pathogenesis of ANOCA. Thus, it is important to assess coronary microvascular function (CMF). However, it has not been clarified what clinical factors or lesion characteristics on coronary angiography (CAG) affect CMF. Thus, we investigated the relationship between CMF and clinical factors or lesion characteristics on CAG in patients with ANOCA.

Methods

Thirty-four patients with chest pain, who underwent CAG, spasm provocation test (SPT) and CMF test, were enrolled. We excluded patients who had moderate coronary stenosis (% stenosis >30%). In the SPT with acetylcholine for left coronary artery and right coronary artery (RCA), the coronary spasm was defined as >90% narrowing of coronary artery on CAG accompanied with chest symptoms and/or ST-T changes on ECG during SPT, and coronary microvascular spasm (MVS) was defined as ≤90% narrowing of coronary artery on CAG with accompanied with chest pain and ST-T changes during SPT. In each coronary artery, the presences of atherosclerosis (20%≤%stenosis≤30%), focal spasm (spasm occurred within one segment of AHA classification), diffuse spasm (spasm occurred over two segments of AHA classification) and MVS, were checked. In the CMF test with a pressure-wire during adenosine triphosphate infusion, the index of microvascular resistance (IMR) was measured. IMR values were obtained in 34 of the left anterior descending coronary artery (LAD) and 12 in RCA. In each patient, conventional coronary risk factors, blood chemical parameters, peripheral endothelial function such as flow-mediated dilation (FMD) of brachial artery and left ventricular mass index (LVMI) were checked.

Results

In 34 patients, clinical factors including blood chemical parameters, FMD and LVMI, except for smoking status did not affect IMR values on LAD. Only the smoking status was associated with IMR values as follows: median IMR values were 44, 22 and 25 in current smokers (n=5), past smokers (n=8) and never smokers (n=21, p=0.03), respectively. In 46 coronary arteries, the presence of atherosclerosis, the type of the coronary spasm, such as focal and diffuse spasm and MVS, did not affect the IMR values, however, it was significantly higher in the RCA (median 38) than that in the LAD (median 26, p=0.02).

Conclusion

These results suggest that smoking status affected CMF in patients with ANOCA, suggesting the possibility of improvement of CMF by stop smoking in such patients. In addition, in the assessment of CMF, it may be important to take into account which coronary artery being evaluated.

Funding Acknowledgement

Type of funding sources: None.

Clinical characteristics and prognosis in patients with multi-vessel coronary spasm – comparison with those in patients with single-vessel coronary spasm

Background

We have sometimes experienced patients with vasospastic angina (VSA), who showed multi-vessel spasm (MVS) on coronary angiography (CAG) and spasm provocation test (SPT). However, it has not been clarified what clinical characteristics VSA patients with MVS have or whether such patients have poor prognosis. Therefore, we compared the clinical characteristics and prognosis in VSA patients with MVS with those in VSA patients with single-vessel spasm (SVS).

Methods

One hundred and fifty-two patients (mean age: 67 yrs, 74 men and 78 women) with VSA, in which presence of coronary spasm was assessed in both left coronary artery (LCA) and right coronary artery (RCA) on SPT, were subjected. We defined VSA as the presence of more than 90% narrowing of the epicardial coronary artery on angiograms, accompanied by the usual chest symptoms and/or ischemic ST-T changes on electrocardiogram. On SPT, MVS was defined as the presence of spasm on ≥ two major coronary arteries. Base on the presence of MVS, patients were divided into the following 2 groups: MVS group and SVS group. The frequencies of conventional coronary risk factors, the average times of anginal attack (per month), the findings of SPT such as spasm provocation induced by low dose of acetylcholine (LDA) and total occlusion due to coronary spasm (TOC), the number of coronary vasodilators at discharge, and the major cardiovascular events (MACE) including death of any cause and readmission due to heart failure, acute coronary syndrome and unstable angina, were compared in the two groups.

Results

There were 98 patients (64%) in the MVS group and 54 patients (36%) in the SVS groups. The frequencies of conventional coronary risk factors and the average times of anginal attacks (4/month in both groups) were not different in the two groups. The frequencies of LDA (33% in MVS and 17% in SVS, p<0.05) and TOC (12% in MVS, 0% in SVS, p<0.01) were higher in the MVS group than in the SVS group. The average numbers of coronary vasodilators was higher in the MVS group (1.1±0.4) than in the SVS group (0.9±0.4, p<0.01). The frequency of MACE did not differ in the two groups as follows (figure).

Conclusions

These findings suggest that there was no clinical characteristic, suggesting the presence of MVS in VSA patients. Such patients may have higher VSA activity on SPT and have more aggressive medications, leading to the similar prognosis in VSA patient with SVS.

Funding Acknowledgement

Type of funding sources: None.

Perfusion-metabolic mismatch in myocardial scintigraphy in patients with vasospastic angina: what does it mean clinically?

Background

It has been reported that perfusion-metabolic mismatch (PMM) in thallium-201 (Tl) and 123I-βmethyl-p-iodophenyl-pentadecanoic acid (BMIPP) shows important information regarding myocardial ischemia in the clinical setting. Such findings have been frequently obtained, even in patients with vasospastic angina (VSA). However, it has not been fully clarified what such findings mean clinically in patients with VSA. There, we investigated the frequency of PMM in patients with VSA as well as clinical characteristics of patients with VSA who have PMM.

Methods

Seventy-eight patients (mean age: 70 yrs, 29 men and 49 women) were diagnosed with VSA by coronary angiography and spasm-provocation test (SPT). We defined VSA as the presence of more than 90% narrowing of the epicardial coronary artery on angiograms, accompanied by the usual chest symptoms and/or ischemic ST-T changes on electrocardiogram. On SPT, multi-vessel spasm was defined as the presence of spasm on ≥ two major coronary arteries. Dual myocardial scintigraphy with Tl and BMIPP was performed, and the presence of PMM was defined as the summed rest score (SRS) in BMIPP scintigraphy ≥4 and difference in SRS in BMIPP and Tl-201 ≥4. Patients were divided into two groups according to the presence of PMM: Group I (+PMM, n=30) and Group II (−PMM, n=48). Each patient with VSA was assessed for conventional coronary risk factors, numbers of angina attacks per month, and taking vasodilators.

Results

Age, gender distribution, and conventional risk factors were not different between the groups. The median number of angina attacks was higher in the Group I than in the Group II (Group I: 4.5 vs. Group II: 0.1, p<0.01), and fewer patients were taking vasodilators in Group I (Group I: 1.1±1.0 vs. Group II: 1.5±1.1, p<0.05). On SPT, the presence of multi-vessels spasm was significantly higher in Group I (76%) than Group II (44%, p<0.05). Logistic regression analysis showed that the presence of multi-vessels spasm (p<0.05) and taking a smaller amount of vasodilators (p<0.05) were associated with PMM.

Conclusions

These findings suggest that PMM in Tl and BMIPP scintigraphy are associated with multi-vessels spasm and a smaller amount of vasodilator medication. This imaging data may provide important information regarding activity of VSA and sufficient medication.

Funding Acknowledgement

Type of funding source: None

P3579Clinical characteristics of an intracoronary erosion and thrombus in patients with vasospastic angina

Background

Intracoronary erosion and thrombus are sometimes detected in patients with vasospastic angina (VSA) through intracoronary imaging modalities. However, the clinical characteristics of these intracoronary findings remain unclear. Therefore, we assessed the clinical and lesion characteristics of these intracoronary abnormalities in patients with VSA.

Methods

We included 48 patients with VSA who underwent coronary angiography (CAG), spasm provocation test (SPT), and coronary angioscopy (CAS). In all patients, acetylcholine was infused in the left and right coronary arteries. The vessels were classified into spastic vessels (SVs) and non-spastic vessels (NSVs) based on SPT results. SVs that could not be observed using CAS were excluded from the study. CAG and SPT findings were evaluated for the presence of atherosclerotic lesions (%stenosis <30%) and types of spasm (segmental or diffuse). Two experts examined the presence of an intracoronary erosion and thrombus on CAS. Other serious symptoms such as cold sweating or syncope were also assessed.

Results

Among the 48 patients, intracoronary erosion and thrombus were detected in 11 (23%) and 10 (21%) patients, respectively, and total intracoronary abnormalities were observed in 17 (35%) patients. Male sex (p<0.05), smoking (p<0.05), and presence of other serious symptoms (p<0.01) were associated with the presence of intracoronary abnormalities. The logistic regression analysis showed the presence of other serious symptoms to be the only factor associated with the presence of intracoronary abnormalities (p<0.05). In the lesion analyses, among the 72 vessels, intracoronary abnormalities were observed only in SVs (17/53, 33%) but not in NSVs (0/19, 0%, p<0.01). Among the 53 SVs, the presence of atherosclerotic lesions (p<0.05) and segmental spasm type (p<0.05) were found to be associated with the presence of intracoronary abnormalities.

Conclusions

Intracoronary erosion and thrombus were observed in approximately 35% of patients with VSA. Such intracoronary abnormalities may be partly affected by the forms of the coronary artery and coronary spasm, leading to the onset of serious symptoms of VSA.

Relation between C reactive protein concentrations and coronary microvascular endothelial function

OBJECTIVE

To determine how C reactive protein (CRP), a sensitive marker of inflammation, is related to coronary endothelial function.

DESIGN

Changes in quantitative coronary angiographic findings and Doppler flow velocity measurements in response to locally infused acetylcholine were assessed.

SETTING

Tertiary cardiology centre.

PATIENTS

46 patients with angiographically normal coronary arteries were divided into groups with normal (< or = 3 mg/l) or increased (> 3 mg/l) CRP concentrations.

INTERVENTIONS

Acetylcholine (3 and 30 microg/min) was infused into the left coronary ostium for two minutes.

MAIN OUTCOME MEASURES

Percentage change in diameter of epicardial coronary arteries and coronary blood flow (CBF) in response to acetylcholine; and correlations between these parameters and serum CRP concentrations.

RESULTS

15 patients had increased CRP concentrations. The change in coronary artery diameter induced by acetylcholine infusion was similar between the groups but the increase in CBF induced by acetylcholine was smaller in patients with increased CRP concentrations (54.9% v 139.4% with acetylcholine 30 microg/min, p = 0.0030). Multivariate analysis identified increased CRP concentration as independently associated with attenuated CBF response to acetylcholine at 30 microg/min (p = 0.0078, R2 = 0.434).

CONCLUSIONS

These findings suggest that inflammation appears to be associated with impaired coronary endothelial function in resistance but not conduit vessels. The data suggest a close relation between chronic vascular inflammation and endothelial dysfunction in atherosclerosis.

Tetrahydrobiopterin restores endothelial function of coronary arteries in patients with hypercholesterolaemia

OBJECTIVE

To examine the effect of tetrahydrobiopterin (BH4), an essential cofactor for nitric oxide synthase, on coronary artery endothelial function in hypercholesterolaemic patients.

DESIGN

Quantitative coronary angiography and Doppler flowmetry were used to examine the effects of intracoronary infusion of BH4 on vascular response to acetylcholine (ACh).

SETTING

Tertiary cardiology centre.

PATIENTS

18 patients with angiographically normal coronary arteries, of whom nine had hypercholesterolaemia and nine had noromocholesterolaemia.

INTERVENTIONS

ACh (3 and 30 microg/min) was infused for two minutes into the left coronary ostium. ACh was then simultaneously infused with BH4 (1 mg/min) before and after infusion of L-N(G)-monomethyl-L-arginine (L-NMMA) (40 micromol/min for five minutes).

MAIN OUTCOME MEASURES

Diameter of the epicardial coronary arteries and coronary blood flow.

RESULTS

In hypercholesterolaemic patients, BH4 attenuated the ACh induced decrease in coronary diameter (p < 0.05) and restored the ACh induced increase in coronary blood flow (p < 0.05). In normocholesterolaemic patients, BH4 did not affect the ACh induced changes in coronary diameter or coronary blood flow. In both groups, L-NMMA decreased the baseline coronary diameter (p < 0.05) and baseline coronary blood flow (p < 0.05). In hypercholesterolaemic patients, L-NMMA inhibited both the BH4 mediated attenuation of the ACh induced decrease in coronary diameter (p < 0.05) and the BH4 mediated enhancement of the ACh induced increase in coronary blood flow (p < 0.01).

CONCLUSIONS

Intracoronary infusion of BH4 restores coronary endothelial function by improving the bioavailability of endothelium derived nitric oxide in hypercholesterolaemic patients.

Endothelial dysfunction is an independent factor responsible for vasospastic angina

In order to evaluate peripheral endothelial function in patients with vasospastic angina (VSA), we measured flow-mediated dilation (FMD) of the brachial artery in patients with VSA and compared it with FMD in patients without VSA. Endothelial dysfunction is considered one of the mechanisms underlying VSA. However, its exact role remains to be clarified. The study included 30 patients with positive spasm-provocational test results without evidence of significant coronary stenosis (VSA group) and 30 patients with negative spasm-provocational test results without evidence of significant coronary stenosis (control group). In each patient, brachial artery diameter responses to hyperemic flow and glyceryl trinitrate spray were measured using high-resolution ultrasound. The carotid intima-media thickness was also measured as a marker of systemic atherosclerosis. FMD was lower in the VSA group (4.8+/-0.5%) compared with the control group (9.4+/-0.7%, P<0.0001). In the VSA group, FMD was not affected by coronary risk factors or the presence of atherosclerotic changes on coronary angiography. Glyceryl trinitrate-induced dilation did not differ between the two groups. The intima-media thickness was comparable between the VSA (0.85+/-0.04 mm) and control groups (0.81+/-0.05 mm). These findings indicated that peripheral endothelial function is impaired only in the VSA group, whereas the atherosclerotic changes were similar in the two groups. We conclude that endothelial dysfunction may be an independent factor responsible for the development of VSA.

Usefulness of flow-mediated dilation of the brachial artery and/or the intima-media thickness of the carotid artery in predicting coronary narrowing in patients suspected of having coronary artery disease

It has been reported that flow-mediated dilation (FMD) of the brachial artery and the carotid intima-media thickness (IMT), markers of atherosclerosis, are altered in patients with coronary artery disease (CAD), but it is still not known if the presence of CAD can be detected using these markers. We examined whether the presence of CAD can be detected by FMD of the brachial artery and/or IMT. Eighty-one patients who underwent coronary angiography for the first time were enrolled. In each patient, brachial artery diameter responses to FMD and the administration of nitroglycerin spray, and carotid IMT were measured using high-resolution ultrasound (10 MHz) before coronary angiography. CAD was defined as >50% stenosis of a major coronary artery. Fifty-six patients had CAD. FMD was lower and IMT was greater in patients with CAD (FMD, 2.9 +/- 0.2% vs 9.4 +/- 0.5%; IMT, 1.09 +/- 0.05 vs 0.79 +/- 0.04 mm, both p <0.0001). Nitroglycerin-induced dilation did not differ in the 2 groups. Multivariate analysis showed that FMD was the only predictor of the presence of CAD (p = 0.0026). Receiver-operating characteristic analysis demonstrated that a cutoff value for FMD for detecting the presence of CAD was 6%, with a sensitivity of 0.93 (52 of 56) and a specificity of 0.88 (22 of 25). These findings suggest that FMD but not IMT may be used to detect the presence of CAD in patients with suspected CAD.

Magnesium causes nitric oxide independent coronary artery vasodilation in humans

OBJECTIVE

To determine how magnesium affects human coronary arteries and whether endothelium derived nitric oxide (EDNO) is involved in the coronary arterial response to magnesium.

DESIGN

Quantitative coronary angiography and Doppler flow velocity measurements were used to determine the effects of the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA) on magnesium induced dilation of the epicardial and resistance coronary arteries.

SETTING

Hiroshima University Hospital a tertiary cardiology centre.

PATIENTS

17 patients with angiographically normal coronary arteries.

INTERVENTIONS

Magnesium sulfate (MgSO(4)) (0.02 mmol/min and 0.2 mmol/min) was infused for two minutes into the left coronary ostium before and after intracoronary infusion of L-NMMA.

MAIN OUTCOME MEASURES

Diameter of the proximal and distal segments of the epicardial coronary arteries and coronary blood flow.

RESULTS

At a dose of 0.02 mmol/min, MgSO(4) did not affect the coronary arteries. At a dose of 0.2 mmol/min, MgSO(4) caused coronary artery dilation (mean (SEM) proximal diameter 3.00 (0.09) to 3.11 (0.09) mm; distal 1.64 (0.06) to 1.77 (0.07) mm) and increased coronary blood flow (79.3 (7.5) to 101.4 (9.9) ml/min, p < 0.001 v baseline for all). MgSO(4) increased the changes in these parameters after the infusion of L-NMMA (p < 0.001 v baseline).

CONCLUSIONS

Magnesium dilates both the epicardial and resistance coronary arteries in humans. Furthermore, the coronary arterial response to magnesium is dose dependent and independent of EDNO.

Magnesium causes nitric oxide independent coronary artery vasodilation in humans

OBJECTIVE

To determine how magnesium affects human coronary arteries and whether endothelium derived nitric oxide (EDNO) is involved in the coronary arterial response to magnesium.

DESIGN

Quantitative coronary angiography and Doppler flow velocity measurements were used to determine the effects of the nitric oxide synthase inhibitorNG-monomethyl-L-arginine (L-NMMA) on magnesium induced dilation of the epicardial and resistance coronary arteries.

SETTING

Hiroshima University Hospital a tertiary cardiology centre.

PATIENTS

17 patients with angiographically normal coronary arteries.

INTERVENTIONS

Magnesium sulfate (MgSO4) (0.02 mmol/min and 0.2 mmol/min) was infused for two minutes into the left coronary ostium before and after intracoronary infusion of L-NMMA.

MAIN OUTCOME MEASURES

Diameter of the proximal and distal segments of the epicardial coronary arteries and coronary blood flow.

RESULTS

At a dose of 0.02 mmol/min, MgSO4 did not affect the coronary arteries. At a dose of 0.2 mmol/min, MgSO4 caused coronary artery dilation (mean (SEM) proximal diameter 3.00 (0.09) to 3.11 (0.09) mm; distal 1.64 (0.06) to 1.77 (0.07) mm) and increased coronary blood flow (79.3 (7.5) to 101.4 (9.9) ml/min, p < 0.001 vbaseline for all). MgSO4 increased the changes in these parameters after the infusion of L-NMMA (p < 0.001v baseline).

CONCLUSIONS

Magnesium dilates both the epicardial and resistance coronary arteries in humans. Furthermore, the coronary arterial response to magnesium is dose dependent and independent of EDNO.

The preventive effect of magnesium on coronary spasm in patients with vasospastic angina

STUDY OBJECTIVES

Previous studies have reported that magnesium (Mg) deficiency is associated with coronary spasm. However, little is known about the preventive effect of Mg on coronary spasm. The present study investigated whether Mg prevents coronary spasm in patients with vasospastic angina (VSA).

DESIGN

Effectiveness trial.

SETTING

University medical center.

PATIENTS

Twenty-two patients with VSA.

INTERVENTION

Coronary spasm was induced with an intracoronary infusion of acetylcholine (Ach). After spontaneous relief of the coronary spasm, Mg sulfate (0.27 mmol/kg body weight) was infused IV over 20 min in 14 patients and isotonic glucose was infused in 8 patients as control subjects. Intracoronary infusion of Ach was then repeated, and the diameter of the coronary arteries was measured quantitatively.

MEASUREMENTS AND RESULTS

Mg infusion caused coronary artery dilatation at baseline in both the spastic (5. 9 +/- 2.3%) and nonspastic segments (5.5 +/- 1.5%). Mg infusion reduced the severity of chest pain and ST-segment deviations during coronary spasm. After the Mg infusion, the percent change in the diameter of the spastic segments improved from - 62.8 +/- 2.6% to - 43.7 +/- 4.7% during coronary spasm. Overall, 10 of 14 patients (71%) responded favorably to Mg infusion. Isotonic glucose infusion did not elicit changes in chest pain severity, ST-segment deviations, or the diameter of the coronary arteries during spasm.

CONCLUSIONS

Mg infusion produces nonsite-specific basal coronary dilatation and suppresses Ach-induced coronary spasm in patients with VSA.

The role of nitric oxide in bradykinin-induced dilation of coronary resistance vessels in patients with hypercholesterolemia

OBJECT

In hypercholesterolemic patients, acetylcholine- and substance P-mediated endothelium-dependent dilation of the coronary resistance vessels is impaired due to decreased nitric oxide production. However, it is not clear if bradykinin-induced coronary vasodilation is impaired in these patients. We investigated whether the endothelium-dependent dilation of coronary resistance vessels mediated by bradykinin is impaired in patients with hypercholesterolemia and, if so, whether this impairment is caused by a decreased production of nitric oxide.

METHODS

We examined the coronary vascular responses to acetylcholine and bradykinin. The vascular responses to bradykinin were also assessed after N(G)-monomethyl-L-arginine was infused to inhibit nitric oxide production. Drugs were infused into the left coronary ostium and coronary blood flow (CBF) and coronary vascular resistance were evaluated by quantitative angiography and Doppler flow velocity measurements.

PATIENTS

Twelve hypercholesterolemic patients and 11 control patients with angiographically normal coronary arteries were studied.

RESULTS

The vasodilator responses to acetylcholine and bradykinin were reduced in hypercholesterolemic patients compared with control patients (p<0.005 and p<0.04, respectively, by two-way analysis of variance (ANOVA)). The CBF responses to acetylcholine and bradykinin were significantly correlated (r=0.56; p<0.01). Bradykinin-induced dilation was similar in hypercholesterolemic patients and control patients after inhibition of nitric oxide.

CONCLUSION

These results suggest that the bradykinin-mediated endothelium-dependent dilation of coronary resistance vessels may be impaired due to depressed nitric oxide production in patients with hypercholesterolemia.

Assessment of the severity of coronary artery stenosis by the ratio of the regional washout rate determined by adenosine triphosphate stress Tl-201 SPECT

BACKGROUND

Adenosine triphosphate stress thallium-201 single-photon emission computed tomography (ATP SPECT) is useful for diagnosis of coronary artery disease, but its usefulness for evaluating the severity of coronary artery stenosis has not been established.

METHODS AND RESULTS

We performed region-of-interest analysis of short-axis images obtained by ATP SPECT in 31 patients with single-vessel disease (>50% stenosis of the luminal diameter). We selected the lowest and highest washout rates (WR) among the anterior, lateral, and inferior WRs and calculated the ratio of the lowest WR to the highest WR (WR ratio = 0.925+/-0.027 in 14 control subjects). ATP SPECT showed positive results in 29 (94%) of 31 patients. The severity of coronary artery stenosis was inversely correlated with the WR ratio (r = -0.703, P < .0001). The sensitivity and specificity of a WR ratio < or = 0.660 for the diagnosis of severe coronary stenosis (> or =80% stenosis) were 83% and 80%, respectively.

CONCLUSIONS

Results suggest that ATP SPECT may be useful for assessment of the severity of coronary artery stenosis in patients with single-vessel disease.

[Magnesium (Mg) status in patients with cardiovascular diseases]

Mg is the fourth most abundant total cation in the human body and the second most abundant intracellular cation. Moreover, Mg is an important cofactor for many enzymes especially those involved in phosphate transfer reactions. Mg is therefore essential in the regulation of the metabolism of other ions and cellular functions. Mg deficiency has been shown to be associated with fatal cardiovascular diseases such as cardiac arrhythmias and coronary heart disease, as well as with risk factors for these diseases, such as hypertension, and diabetes mellitus. Clinical evaluation of Mg status has been limited by the lack of suitable technology for measuring this cation. Although the measurement of serum total Mg is routinely available, ionized Mg is physiologically active. Furthermore, most of the body's Mg is present in the intracellular space. Our findings showed that serum total Mg was similar in all groups, but patients with arrhythmias and diabetes mellitus revealed lower levels of serum ionized Mg. On the other hand, patients with essential hypertension exhibited higher intraerythrocyte Mg concentrations than healthy controls. The measurement of serum total Mg may obscure the diagnosis of an abnormality in Mg metabolism in patients with arrhythmias and diabetes mellitus. Furthermore, the intracellular accumulation of Mg does not support the hypothesis of Mg deficiency in patients with essential hypertension.

Relation between QT dispersion and adenosine triphosphate stress thallium-201 single-photon emission computed tomographic imaging for detecting myocardial ischemia and scar

It is not known if QT dispersion is useful for detecting coronary artery disease. We investigated whether QT dispersion at baseline and during adenosine triphosphate (ATP) infusion correlate with the imaging patterns obtained from ATP stress thallium-201 single-photon emission computed tomography (ATP-SPECT). QT dispersion was determined in 169 patients who underwent ATP-SPECT from 12-lead electrocardiograms obtained at baseline and 3 minutes after the beginning of ATP infusion. Based on the results of ATP-SPECT, patients were divided into 4 groups: normal (n = 55), ischemia (n = 38), ischemia and scar (n = 42), and scar (n = 34). Baseline QT dispersions (mean +/- SD) in the normal, ischemia, ischemia and scar, and scar groups were 48 +/- 15, 50 +/- 17, 69 +/- 25, and 70 +/- 24 ms, respectively. Baseline QT dispersion was significantly greater in the groups with myocardial scar. QT dispersions during ATP infusion were 43 +/- 16, 63 +/- 20, 76 +/- 20, and 62 +/- 25 ms in the normal, ischemia, ischemia and scar, and scar groups, respectively. QT dispersion increased with ATP infusion in patients with myocardial ischemia. QT dispersion at baseline and during ATP infusion correlated with the ATP-SPECT imaging pattern. These findings suggest that baseline QT dispersion and ATP-induced changes in QT dispersion may help detect the presence of myocardial ischemia and scar.

Idiopathic verapamil-sensitive left ventricular tachycardia complicated by right ventricular outflow tract ventricular tachycardia and ventricular fibrillation

Idiopathic ventricular tachycardias (VTs) are generally divided into those arising from the right ventricle and those arising from the left ventricle. There has been few reports of two morphologically distinct VT occurring in patients with no apparent structural heart disease. We report a patient with verapamil-sensitive left VT with a right bundle branch block pattern that spontaneously changed to VT with a left bundle branch block pattern. Ventricular fibrillation was induced by the application of programmed stimulation. Although it is unclear if our patient with pleomorphic VT has ventricular vulnerability, it is necessary to investigate further and follow him carefully.

Adenosine 5'-triphosphate induced dilation of human coronary microvessels in vivo

OBJECT

This study was performed to compare the coronary microvascular response to adenosine 5'-triphosphate (ATP) with the response to adenosine in humans.

METHODS

Coronary blood flow velocity was determined using a Doppler flow wire. After intracoronary nitroglycerin infusion, intracoronary bolus injections of adenosine (20 microg) and ATP (20 microg) were performed to induce reactive hyperemia.

PATIENTS

Twenty-nine patients (23 men and 6 women, mean age: 63+/-9 years) with coronary artery disease and risk factors for coronary atherosclerosis were studied.

RESULTS

Coronary flow reserve in response to ATP was similar to that for adenosine (2.7+/-0.7 vs. 2.7+/-0.7). However, the duration of ATP-induced vasodilation was longer than that of adenosine-induced dilation (39+/-25 seconds vs. 26+/-12 seconds, p<0.0001). The coronary flow reserve obtained with either ATP or adenosine was significantly reduced in the interventioned arteries compared with non-stenosed arteries. The coronary flow reserve obtained with ATP was similar to that obtained with adenosine in both artery groups. The duration of the vasodilator effect of ATP was significantly greater than that of adenosine in both artery groups.

CONCLUSION

These results suggest that ATP induces maximal dilation of coronary microvessels, most likely through an endothelium-independent mechanism. The degradation of ATP to adenosine 5'-monophosphate (AMP) and adenosine, as well as the direct action of ATP on A2-adenosine receptors may be responsible for the dilation. We conclude that coronary flow reserve can be determined safely with intracoronary ATP administration.

Vasomotility and nitric oxide bioactivity of the bridging segments of the left anterior descending coronary artery

We compared bridging and nonbridging coronary artery segments with respect to the vasoconstrictor effect of acetylcholine. Bridging segments were hypersensitive to the constrictor effect of acetylcholine, and results suggest that the effect of nitric oxide on the acetylcholine-stimulated condition is decreased, or that the smooth muscle sensitivity to acetylcholine is increased.

Portal-hepatic venous shunt through a portal aneurysm complicated by hepatic encephalopathy and pulmonary hypertension

We report a rare case of portal-hepatic venous shunt through an enormous portal aneurysm complicated by pulmonary hypertension. A 66-year-old woman was admitted to our hospital for hepatic encephalopathy. Chest roentgenography revealed pulmonary hypertension. Computed tomography and ultrasound examination demonstrated a shunt between the portal and hepatic veins through an enormous portal aneurysm. The diagnoses of portal-hepatic venous shunt and pulmonary hypertension were confirmed by hepatic venous catheterization and cardiac catheterization. Pulmonary hypertension might result from the effects of vasoconstrictive agents, which should be metabolized by the liver in normal subjects, passing through the intrahepatic shunt into the lung.

Adverse effects of interferon on the cardiovascular system in patients with chronic hepatitis C

The therapeutic effects of interferon in chronic hepatitis C and many of its adverse effects have been well documented. However, there are only a few reports regarding its adverse effects on the cardiovascular system. The aim of this study was to clarify the clinical features of the adverse effects of interferon on the cardiovascular system in patients with chronic hepatitis C. We monitored 295 patients with chronic active hepatitis C during 312 courses of interferon therapy and for 1 year after the end of treatment for the presence of cardiovascular adverse effects. We found 6 patients with cardiovascular adverse effects during interferon therapy and 4 more patients within 1 year after the end of therapy (10/312, 3.2%). The adverse effects of interferon on the cardiovascular system included arrhythmia (n = 4), ischemic heart disease (n = 4) and myocardial disease (n = 2). None of the clinical factors, including history of cardiovascular disease, were related to these cardiovascular adverse effects. In all instances the patient's condition improved after discontinuation of interferon and adequate therapy. The cardiovascular adverse effects of interferon occurred frequently in patients with chronic hepatitis C, even after the end of therapy and they were unpredictable. Thus, all patients undergoing interferon therapy should be monitored not only during but also after the end of treatment.

Sarcoidosis after interferon therapy for chronic active hepatitis C

Sarcoidosis is characterized by multisystemic granulomatous lesions of unknown etiology. A 62-year-old woman developed sarcoidosis after treatment with alpha-2a interferon (IFN) for 24 weeks (total dose: 522 million units) for chronic hepatitis C. She developed complete atrioventricular block and multiple noncaseating granulomatous lesions in the lung. IFN therapy, which may disturb cellular immune activation in some patients, may have contributed to the onset and progression of sarcoidosis.

Cardiogenic shock following recombinant alpha-2b interferon therapy for chronic hepatitis C. A case report

A 57-year-old woman with chronic hepatitis C was treated with alpha-2b interferon (IFN). Forty-five days after the initiation of IFN therapy, she developed cardiogenic shock. Acute perimyocarditis as a cause of cardiogenic shock was clinically suspected by the findings of complete atrioventricular block, regional wall motion abnormality and pericardial effusion. Since IFN therapy may induce cardiogenic shock in some patients, it is important to carefully monitor patients under treatment with IFN for abnormal cardiac signs.

Short- and mid-term follow-up results after percutaneous transvenous mitral commissurotomy

This study reports the clinical follow-up for 6 months of 52 patients who underwent percutaneous transvenous mitral commissurotomy (PTMC). PTMC resulted in an increase in mitral valve area from 1.1 +/- 0.3 to 1.7 +/- 0.4 cm2 (p < 0.0001), a decrease in mean left atrial pressure from 16 +/- 7 to 13 +/- 5 mmHg (p < 0.0001), and an increase in exercise time from 4.6 +/- 2.1 to 6.3 +/- 2.3 min (p < 0.0001). At 6 months follow-up, mitral valve area was unchanged (1.7 +/- 0.4 cm2). Of 52 patients, 33 showed clinical improvement and 19 had no clinical improvement after PTMC. Univariate analysis showed (1) younger age, (2) echocardiographic score of 8 or less, (3) existence of mitral regurgitation of less than grade 2 after PTMC, and (4) amelioration in left atrial dimension, mean pulmonary artery pressure and exercise time after PTMC as correlative factors for clinical improvement. In conclusion, PTMC was an effective procedure for mitral stenosis, especially in younger patients with an echocardiographic score of 8 or less. Change in left atrial dimension was a good indicator of the effectiveness of PTMC.