Age-dependent impairment of coronary collateral development in humans

The purpose of this study was to evaluate whether age influences collateral development in patients with coronary artery disease. The extent of collateral development to the area perfused by the infarct-related artery was graded, depending on the degree of opacification of the occluded infarct-related artery. We evaluated the extent of collateral development using coronary cineangiography in 102 patients with an acutely occluded infarct-related coronary artery within 12 h after the onset of the first acute myocardial infarction, and who had a history of long-standing effort angina. Well-developed collateral circulation was observed in 54 (53%) of the patients. The patients were divided into two groups based on their age. The prevalence of well-developed collateral circulation in the younger group (< or = 64 years, n = 48) was 69% (33 of 48), being significantly (P = 0.003) higher than 39% (21 of 54) in the older group (> or = 65 years, n = 54). We conclude that in the presence of stimuli for collateral development i.e., long-standing effort angina accompanied by severe coronary stenosis, the age of patients is a key determinant of collateral development.

A nuclear complex containing PPARalpha/RXRalpha is markedly downregulated in the hypertrophied rat left ventricular myocardium with normal systolic function

The expression of genes encoding fatty acid utilization enzymes is coordinately downregulated during the development of cardiac hypertrophy and failure. However, molecular mechanisms that mediate this downregulation are unknown. Peroxisome proliferator-activated receptor (PPAR) response elements (PPREs) have been identified in promoters of many genes involved in fatty acid utilization, where they function as positive regulatory elements. PPARs bind to PPREs as heterodimers with retinoid X receptors (RXRs). Primary cardiac myocytes from neonatal rats were transfected with a reporter construct driven by the C promoter of rat acyl-coenzyme A synthetase (ACS) gene. Stimulation with phenylephrine, a potent inducer of hypertrophy, markedly downregulated the activity of this promoter. By use of electrophoretic mobility-shift assays (EMSAs) using PPRE in the rat ACS promoter as a probe, we found a sequence-specific protein-DNA complex in the nuclear extract from adult rat left ventricular (LV) myocardium. Supershift experiments revealed that this complex was immunoreactive for PPARalpha and RXRalpha. We compared the activity of this complex in LV nuclear extracts from Dahl salt-sensitive rats (DSs) with hypertension and control age-matched Dahl salt-resistant rats (DRs). Even at the stage of concentric LV hypertrophy with normal systolic function, the activity of the band was markedly diminished in DSs compared with DRs. However, immunoblot analyses showed no difference in LV expression levels of PPARalpha or RXRalpha between DSs and DRs. These findings indicate that a nuclear complex of PPARalpha/RXRalpha is present in adult rat LV and is markedly downregulated in the hypertrophied LV from DS rats, which may account for the loss of transcriptional activation. The downregulation of this complex precedes LV systolic dysfunction and is mediated at the posttranslational levels.

Enhanced external counterpulsation improved myocardial perfusion and coronary flow reserve in patients with chronic stable angina; evaluation by(13)N-ammonia positron emission tomography

AIMS

The mechanism by which enhanced external counterpulsation therapy exerts its beneficial effects on chronic and symptomatic stable angina is largely unknown. To clarify the mechanism of action of enhanced external counterpulsation, we used(13)N-ammonia positron emission tomography to evaluate myocardial perfusion.

METHODS AND RESULTS

This was not a randomized controlled study. Eleven patients (eight male, age: 61.6+/-9.7) with angina pectoris underwent enhanced external counterpulsation therapy for 35 1 h sessions. They underwent a treadmill exercise test and(13)N-ammonia positron emission tomography, both at rest and with dipyridamole, before and after enhanced external counterpulsation therapy. Neurohumoral factors and nitric oxide were also evaluated. Myocardial perfusion increased at rest after therapy (0.69+/-0.27 to 0.85+/-0.47 ml x min(-1) x g(-1), P<0.05). In ischaemic regions, particularly the anterior region, myocardial perfusion at rest and with dipyridamole and coronary flow reserve improved significantly after therapy (at rest: 0.71+/-0.26 to 0.86+/-0.31;P<0.05, with dipyridamole: 1.26+/-0.65 to 1.84+/-0.94;P<0.02, coronary flow reserve: 1.75+/-0.24 to 2.08+/-0.28;P<0.04). Exercise time was prolonged and the time to 1-mm ST depression improved markedly (P<0.01). After therapy, nitric oxide levels increased (P<0.02) and neurohumoral factors decreased.

CONCLUSIONS

Enhanced external counterpulsation therapy improved myocardial perfusion at rest and with dipyridamole and was associated with an increased exercise tolerance with(13)N-ammonia positron emission tomography and increased nitric oxide levels. These results suggest that one of the enhanced external counterpulsation mechanisms is development and recruitment of collateral vessels.

Serial evaluation of fatty acid metabolism in rats with myocardial infarction by pinhole SPECT

BACKGROUND

Iodine 123-labeled 15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) is mainly trapped in the myocardium as triglyceride, depending on the adenosine triphosphate level. Ten percent to 20% of it is metabolized through alpha-oxidation after beta-oxidation; however, the precise mechanism of the regulatory pathways of BMIPP is yet to be clarified.

METHODS AND RESULTS

A brief left coronary artery occlusion (10-30 minutes) was performed in 28 male Wistar-Kyoto rats. Dual single photon emission computed tomography images of BMIPP and thallium 201 were obtained 3 days and 24 days after the operation. The activities of 3-hydroxyacyl-coenzyme A dehydrogenase (HAD), citrate synthase (CS), and alpha-glycerol-phosphate dehydrogenase (GPD) were then measured in both ischemic and nonischemic regions. BMIPP and Tl-201 chloride severity scores were also evaluated conventionally. CS and HAD levels were significantly lower in the ischemic region than in the nonischemic region in the chronic group (CS, 102.9 +/- 28.1 vs 138.7 +/- 33.7 micromol/g/min, respectively, P =.0051; HAD, 54.7 +/- 20.1 vs 78.6 +/- 18.7 micromol/g/min, respectively, P =.0031). There was no difference in GPD between the ischemic and nonischemic regions. The BMIPP severity score had closer inverse relations with HAD (acute, r = -0.82; chronic, r = -0.80) and CS (acute, r = -0.87; chronic, r = -0.81), but not with GPD, than did Tl-201 chloride severity score.

CONCLUSIONS

BMIPP imaging correlates well with the activities of HAD and CS, suggesting that a decrease in BMIPP uptake reflects deterioration of both fatty acid metabolism and citrate cycle and shows information other than regional myocardial perfusion.

Effects of exercise training on myocardial fatty acid metabolism in rats with depressed cardiac function induced by transient ischemia

The effects of exercise training on metabolic and functional recovery after myocardial transient ischemia were investigated in a rat model. Male Wistar Kyoto rats were subjected either to a 30-min left coronary artery occlusion followed by reperfusion or to a sham operation. At 4 weeks after operation, the rats were randomly assigned either to sedentary conditions or to exercise training for 6 weeks. In the ischemic rats, pinhole SPECT (single photon emission computed tomography) imaging with thallium-201 (201Tl) and 123I-(rho-iodophenyl)-3-R,S-methylpentadecanoic acid (BMIPP) showed a reduction of both myocardial perfusion and fatty acid metabolism in the risk zone of the left ventricle (LV). The LV was dilated and the ejection fraction was decreased after ischemic injury. The severity score showed a significant decrease on both 201Tl and BMIPP (201Tl, from 19.9+/-2.7 to 17.0+/-2.2, p<0.05; BMIPP, from 21.5+/-2.4 to 18.6+/-1.9, p<0.05) after exercise training in the ischemic trained rats, but did not change significantly in their sedentary counterparts. Plasma levels of free fatty acids normalized in the ischemic trained rats, but elevated in the ischemic sedentary rats (0.53+/-0.05 vs 0.73+/-0.06 mmol/L, p<0.05). Furthermore, the trained rats had a significant increase in LV stroke volume (0.25+/-0.02 vs 0.21+/-0.01 ml/beat, p<0.05) and adaptive cardiac hypertrophy. These findings demonstrate that adaptive improvements in myocardial perfusion, fatty-acid metabolism and LV function were induced by exercise training after transient ischemia.

Effects of posture on cardiac autonomic nervous activity in patients with congestive heart failure

OBJECTIVES

We aimed to clarify which recumbent position is preferred by patients with congestive heart failure (CHF) and to evaluate whether cardiac autonomic nervous activity is different among three recumbent positions (supine, left lateral decubitus, right lateral decubitus) in patients with CHF.

BACKGROUND

It remains unclear whether cardiac autonomic nervous activity is different among three recumbent positions in patients with CHF.

METHODS

We studied 17 male CHF patients (66+/-7 years) and 17 age- and gender-matched healthy subjects (66+/-7 years). Each subject underwent 24-h ambulatory electrocardiographic monitoring. A channel was used to record the CM5 lead, and another to record the signal of the patient's posture with use of a newly developed small-sized detector (3.2 cm x 3.2 cm). By using spectral analysis of heart rate variability, frequency-domain measures were calculated and compared among the three recumbent positions. Normalized high-frequency (HF: 0.15 to 0.40 Hz) power was used as an index of vagal activity and the low frequency (0.04 to 0.15 Hz)/HF power ratio was used as an index of sympathovagal balance.

RESULTS

In patients with CHF, the time for the right lateral decubitus position was two-fold longer than that for the supine and left lateral decubitus positions. The increased cardiac sympathetic activity and decreased vagal tone in CHF patients were normalized in the right lateral decubitus position.

CONCLUSIONS

The right lateral decubitus position in patients with CHF may be a self-protecting mechanism of attenuating the imbalance of cardiac autonomic nervous activity.

Baroreflex sensitivity and heart rate variability in the identification of patients at risk for life-threatening arrhythmias: implications for clinical trials

BACKGROUND

The need for accurate risk stratification is heightened by the expanding indications for the implantable cardioverter defibrillator. The Multicenter Automatic Defibrillator Implantation Trial (MADIT) focused interest on patients with both depressed left ventricular ejection fraction (LVEF) and the presence of nonsustained ventricular tachycardia (NSVT). Meanwhile, the prospective study Autonomic Tone and Reflexes After Myocardial Infarctio (ATRAMI) demonstrated that markers of reduced vagal activity, such as depressed baroreflex sensitivity (BRS) an heart rate variability (HRV), are strong predictors of cardiac mortality after myocardial infarction.

METHODS AND RESULTS

We analyzed 1071 ATRAMI patients after myocardial infarction who had data on LVEF, 24-hour ECG recording, and BRS. During follow-up (21 +/- 8 months), 43 patients experienced cardiac death, 5 patients had episodes of sustained VT, and 30 patients experienced sudden death and/or sustained VT. NSVT, depressed BRS, or HRV were all significantly and independently associated with increased mortality. The combination of all 3 risk factor increased the risk of death by 22x. Among patients with LVEF<35%, despite the absence of NSVT, depressed BRS predicted higher mortality (18% versus 4.6%, P = 0.01). This is a clinically important finding because this grou constitutes 25% of all patients with depressed LVEF. For both cardiac and arrhythmic mortality, the sensitivity of lo BRS was higher than that of NSVT and HRV CONCLUSIONS: BRS and HRV contribute importantly and additionally to risk stratification. Particularly when LVEF is depressed, the analysis of BRS identifies a large number of patients at high risk for cardiac and arrhythmic mortalit who might benefit from implantable cardioverter defibrillator therapy without disproportionately increasing the number of false-positives.

Myocardial ischemia enhances the expression of acidic fibroblast growth factor in human pericardial fluid

Acidic fibroblast growth factor (FGF) is a potent mitogen that can induce angiogenesis in vivo. We have recently reported a marked increase of basic FGF in the pericardial fluid of patients with severe coronary stenosis and an increase in vascular endothelial growth factor (VEGF) in the pericardial fluid of patients with severe myocardial ischemia. The purpose of this study was to evaluate whether acidic FGF levels in the pericardial fluid are associated with severe myocardial ischemia. Immediately after incision of the pericardium in 48 patients during open-heart surgery, 3-5ml of pericardial fluid was obtained. Concentrations of basic FGF and VEGF in the pericardial fluid were measured using an enzyme-linked immunosorbent assay (ELISA). The ELISA system for human acidic FGF was newly developed using a rabbit antibovine acidic FGF antibody. The patients were divided into three groups (group A: 13 patients undergoing emergency coronary artery bypass grafting (CABG) for unstable angina; group B: 17 patients undergoing elective CABG for stable angina; group C: 18 patients undergoing nonischemic open-heart surgery). The VEGF level in the pericardial fluid in group A was 68 +/- 59pg/ml, which was significantly higher than 33 +/- 9 pg/ml in group B and 31 +/- 20 pg/ml in group C (P < 0.05). The concentrations of basic FGF in the pericardial fluid in groups A and B were 722 +/- 601 and 773 +/- 763pg/ml, respectively, significantly higher than 263 +/- 349pg/ml in group C. The pericardial acidic FGF level in group A was 4,291 +/- 2,336 pg/ml, which was also significantly higher than 2,386 +/- 1,048 pg/ml in group B and 2,589 +/- 990 pg/ml in group C (P < 0.05). The acidic FGF level correlated well with the level of VEGF (r = 0.61, P < 0.0001). It is concluded that the level of acidic FGF in pericardial fluid is associated with severe myocardial ischemia. This result indicates that the release of acidic FGF from the myocardial tissue into pericardial fluid is closely related to severe myocardial ischemia.

Pericardial fluid from patients with ischemic heart disease induces myocardial cell apoptotis via an oxidant stress-sensitive p38 mitogen-activated protein kinase pathway

Factors produced by the heart are accumulated at high concentrations in pericardial fluid. We recently reported that pericardial fluid from patients with ischemic heart disease induces apoptosis in an F2 cell line. To characterize factors in pericardial fluid from patients with ischemic heart disease, we investigated signaling pathways by which this pericardial fluid induces apoptosis in cardiac myocytes. Pericardial fluid from patients with ischemic heart disease markedly increased the percentage of TUNEL-positive myocytes compared with fetal bovine serum. Apoptosis was also confirmed by ladder formation and morphologic features. Apoptosis mediated by this pericardial fluid occurs as readily in cardiac myocytes prepared from neonatal mice nullizygous for p53 as in wild-type littermates. This indicates that p53 is not required for this process. We have found that pericardial fluid from ischemic heart disease elicits a robust increase in phosphorylation of p38 mitogen-activated protein kinase. Specific inhibition of the p38 mitogen-activated protein kinase pathway with SB 203580 almost completely blocked apoptosis mediated by pericardial fluid from ischemic heart disease. Activation of p38 mitogen-activated protein kinase is caused by cellular stress, including oxidants. We have also found that anti-oxidant catalase inhibited pericardial fluid-induced activation of p38 mitogen-activated protein kinase and apoptosis. These findings demonstrate that myocardial cell apoptosis induced by pericardial fluid from patients with ischemic heart disease is mediated by an oxidant stress-sensitive p38 mitogen-activated protein kinase pathway. A possible application of SB 203580 to preserve cardiac function in patients with ischemic heart disease should be discussed.

Pericardial fluid as a new material for clinical heart research

This article will review the results of recent clinical studies relating to the pericardial fluid in patients with various heart diseases. In ischemic patients, several angiogenic growth factors are accumulated in a high concentration in pericardial fluid. These may contribute to the angiogenesis and arteriogenesis, which are self-protecting mechanisms of myocardial ischemia. In congestive heart failure, natriuretic peptides are released into the pericardial fluid in a higher concentration compared with plasma levels. This suggests that these peptides may act as autocrine and/or paracrine factors. Pericardial fluid from ischemic patients induces cell proliferation and apoptosis depending on the cell type. Intrapericardial drug administration may provide a reasonable therapeutic strategy for heart diseases. In conclusion, the analysis of pericardial fluid appears to be a logical approach for elucidation of the pathophysiology of the heart.

Myocardial lipid metabolism in compensated and advanced stages of heart failure: evaluation by canine pacing model with BMIPP

The normal myocardium uses primarily fatty acid as its energy source, but, as heart failure develops, the myocardial fatty acid metabolism is limited. In this study, impairment of the lipid metabolism in heart failure was serially evaluated with 123I-(rho-iodophenyl)3-(R,S)-methylpentadecanoic acid (BMIPP), a radioiodinated fatty acid analog.

METHODS

Rapid ventricular pacing was introduced in 10 beagle dogs. Dogs were subjected to hemodynamic assessment and measurement of catecholamine before and after pacing. After 1 wk (group A; n = 4) and 4 wk (group B; n = 6) of pacing, BMIPP was injected directly into the left anterior descending artery; its extraction, retention, and washout rate in the early phase were calculated, and the metabolites in the myocardium were evaluated using high-performance liquid chromatography. These factors were compared with those of healthy control animals (group C; n = 6).

RESULTS

The left ventricular ejection fraction and cardiac output decreased significantly in groups A and B after pacing. The pulmonary capillary wedge pressure did not change in group A but increased significantly in group B. Plasma norepinephrine increased progressively as heart failure developed but did not reach statistical significance. The washout rate in the early phase increased, significantly in groups A and B compared with that of group C. Extraction and retention of BMIPP did not change in group A. In group B, extraction tended to decrease and retention decreased significantly compared with that of group C. The levels of full metabolite formed by complete oxidation of BMIPP decreased, and backdiffusion of BMIPP increased significantly in groups A and B compared with that of group C. Myocardial blood flow did not change among the three groups.

CONCLUSION

Our study indicates that myocardial fatty acid oxidation begins to be inhibited and that washout of BMIPP increases in the compensated stage of left ventricular dysfunction but that myocardial extraction and retention of fatty acid are definitely impaired in the advanced stage of heart failure. Therefore, as assessed by BMIPP, the myocardial lipid metabolism is related to the pathophysiology of the development and worsening of heart failure.

Evaluation of coronary blood flow reserve by 13N-NH3 positron emission computed tomography (PET) with dipyridamole in the treatment of hypertension with the ACE inhibitor (Cilazapril)

PURPOSE

The purpose of this study was to evaluate the effect of treatment with an angiotensin-converting enzyme (ACE) inhibitor (Cilazapril) for early hypertensive patients in terms of coronary blood flow reserve evaluated by 13NH3-positron emission tomography (PET).

METHODS

Before and after 12 weeks of ACE inhibitor treatment, 13NH3-PET with dipyridamole provocation test was performed, and definite myocardial perfusion and coronary flow reserve (CFR) were calculated.

RESULTS

Compared to our normal subjects previously reported (2.61+/-0.74), average coronary flow reserve was decreased (1.70+/-0.64 in hypertensive patients), and improved after treatment (1.77+/-0.52), but not significantly. Of 12 patients, five (42%) showed improved coronary flow reserve from 1.34 to 1.99 without a significant change in the resting flow. Only one patient (8%) showed deterioration after the ACE inhibitor treatment. The coronary vascular resistance (CVR) after ACE inhibitor treatment of the patients with CFR < 2.0 decreased significantly compared with those with CFR> or = 2.0 (p < 0.03).

CONCLUSIONS

These results indicate that hypertensive patients at the early stage show decreased coronary flow reserve despite having normal resting flow. Treatment with an ACE inhibitor (Cilazapril) for 12 weeks improved coronary flow reserve in 42% of our patients. The CVR of the patients with CFR < 2.0 showed improvement compared to those with CFR> or = 2.0. This result indicates that an ACE inhibitor (e.g., Cilazapril) should be one of the choices for improving CFR if hypertensive patients in early stage show signs of ischemia or diastolic dysfunction, which may be one of the sequels of reserve restriction.

Significant regional heterogeneity of coronary flow reserve in paediatric hypertrophic cardiomyopathy

Previous studies have indicated that cardiac events in young patients with hypertrophic cardiomyopathy (HCM) are related to ischaemia rather than to arrhythmia. We measured coronary flow reserve in paediatric HCM and compared the values with those in adult HCM. We studied 12 patients with HCM including six paediatric (<20 years old; mean 13 years) and six adult patients (>20 years old: mean 62 years), and six healthy young adults (mean 29 years) as controls. Every patient underwent magnetic resonance imaging (MRI) for anatomical assessment. Myocardial blood flow at rest and after dipyridamole infusion was measured with dynamic nitrogen-13 ammonia positron emission tomography (PET). Partial volume effect was corrected for using the anatomical data obtained with MRI. In adult patients with HCM, coronary flow reserve in the hypertrophied septal region was not significantly different from that in the non-hypertrophied lateral wall (1.38+/-0.29 vs 1.77+/-0.39, respectively). In the paediatric patients, coronary flow reserve in the hypertrophied septal region was significantly lower than in the non-hypertrophied lateral wall (0.84+/-0.33 vs 2.74+/-0.90, respectively, P<0.01). In addition, coronary flow reserve in adult patients was lower than in control subjects both in the septal wall (1.38+/-0.29 vs 2.94+/-0.35, respectively, P<0.0001) and in the lateral wall (1.77+/-0.39 vs 2.85+/-0.69, respectively, P<0.05). In contrast, coronary flow reserve in paediatric patients was not significantly different from that in control subjects in the lateral wall (2.74+/-0.90 vs 2.85+/-0.69, respectively), while absolute reduction of myocardial blood flow was noted after pharmacological vasodilatation in the hypertrophied septal region. In conclusion, significant regional differences of coronary flow reserve were present in the paediatric patients with HCM. These results suggest that paediatric patients with HCM intrinsically have the potential to experience significant regional ischaemia even in the absence of coronary stenosis.

[Effect of itraconazole on digoxin clearance in patients with congestive heart failure]

We showed a digoxin-itraconazole interaction in three patients in whom digoxin serum concentrations were increased. Their electrocardiograms revealed arrhythmias such as ventricular premature contraction, atrioventricular block, and ST depression. The elimination half-life of digoxin in case 3 patient who continued itraconazole therapy was 8.4 days, which was estimated by nonlinear least squares method from the serum concentrations of digoxin versus time curve. In order to evaluate the influence of itraconazole on pharmacokinetic parameters of digoxin, we estimated digoxin clearance by the Bayesian method using the population pharmacokinetic parameters in Japanese patients. During the concomitant use of itraconazole and digoxin, the digoxin clearance in all patients decreased to 50.5 +/- 8.8% (mean +/- S.D.) of the clearance without itraconazole. When digoxin and itraconazole are used concomitantly, careful monitoring of digoxin serum concentrations is necessary. Based on our results of digoxin clearance evaluation, the dose of digoxin should be reduced to 50% of original dose after itraconazole is started, and digoxin serum concentration might be controlled at the same level before the concomitant use.

Pericardial fluid from patients with ischemic heart disease accelerates the growth of human vascular smooth muscle cells

The strong association between severe coronary stenosis and collateral growth continues to be a paradigm in this field of investigation. The present study was based on the hypothesis that angiogenic growth factors are produced by ischemic cardiac tissue, are diffusible and more concentrated in pericardial fluid, and accelerate the growth of vascular smooth muscle cells (VSMC). Pericardial fluid from 17 patients with stable or unstable angina or acute myocardial infarction (group A) and from 10 patients with nonischemic heart disease (group B) were collected at the time of open heart surgery. Cultured human aortic VSMC were plated at the third passage at a density of 5x10(3)/100 microl and allowed to attach for 24 h. The 3-day growth assay was preceded by 72 h of growth arrest with 0.4% fetal calf serum (FCS). Growth was restarted by the addition of 90 microl of medium containing 0.4% FCS, and 1O microl of each pericardial fluid. Cell counts on triplicate wells were performed using a dimethylthiazol (MTT) method on days 0 and 3. The effect of pericardial fluid on the growth of VSMC was evaluated as a ratio (R) of cell numbers on day 3 to those on day 0. The concentration of basic fibroblast growth factor (bFGF) in pericardial fluid was measured by an enzyme-linked immunosorbent assay. The concentration of bFGF in pericardial fluid of group A was 633+/-127 pg/ml, and significantly (p=0.003) higher than that of group B (86+/-23 pg/ml). R in group A was 2.29+/-0.18 and significantly (p=0.019) higher than that in group B (1.68+/-0.11). The level of bFGF positively correlated with R (p=0.009). These findings indicate that pericardial fluid from patients with ischemic heart disease contains some substances that mediate collateral development, and bFGF might be one of them.

Pericardial fluid from patients with unstable angina induces vascular endothelial cell apoptosis

OBJECTIVES

The purpose of this study was to investigate whether pericardial fluid from patients with unstable angina (UA) would modulate vascular endothelial cell survival.

BACKGROUND

Apoptosis of vascular endothelial cells promotes the coagulation process, playing an important role in the formation of coronary arterial thrombi. However, little is known about the mechanisms of vascular endothelial cell death in acute coronary syndrome. We hypothesized that factors inducing apoptosis are produced by the ischemic heart and accumulated in high concentrations in pericardial fluid.

METHOD

Pericardial fluid was obtained during coronary artery bypass surgery from patients with UA (group A, n = 8) and those with stable angina (group B, n = 23). A survival assay of F2 cells from a mouse vascular endothelial cell line was performed in the presence of 10% pericardial fluid from each patient.

RESULTS

Pericardial fluid levels of vascular endothelial growth factor were significantly higher in group A than in group B, indicating that group A had more ischemic insults than group B. Pericardial fluid from group A, but not from group B, markedly induced F2 cell death (cell survival relative to fetal bovine serum; group A: 33 +/- 26% vs. group B: 91 +/- 22%, p < 0.01). Cell death was associated with internucleosomal DNA fragmentation, a hallmark of apoptosis. Fractionation of pericardial fluid using a Centricon C-100 demonstrated that apoptosis-inducible activities exist in the Centricon C-100 retentates but not in the filtrates.

CONCLUSIONS

Factors that induce vascular endothelial cell apoptosis are secreted into the pericardial space from the hearts of patients with UA. These factors are large complexes or unknown new proteins larger than 100 kDa.

Evaluation of myocardial infarct size in rat heart by pinhole SPECT

BACKGROUND

High-resolution single photon emission computed tomography (SPECT) with a pinhole collimator is a new method for evaluating the regional properties of radiopharmaceuticals in small laboratory animals in vivo. Although several reports of normal images of rat taken by this new technique are available, there are as yet few reports on its use in disease models, such as myocardial infarction. In this study, we clearly visualized myocardial flow in the rat heart with myocardial infarction using this system, and evaluated the relationship between SPECT images and histologic analysis.

METHODS AND RESULTS

For visualization of myocardial flow in rat heart, 201Tl images were taken just before and 24 days after left coronary artery ligation. The images were taken using a 4-head SPECT scanner with pinhole collimators. The percent infarct size on 201Tl-SPECT imaging (%SI) and the defect score were then assessed and compared with the percent infarct size on histologic analysis (%HI). Both the %SI and defect score correlated well with %HI (r = 0.97 and 0.74, respectively).

CONCLUSION

Serial SPECT imaging using pinhole collimators permits estimates of myocardial flow even in small laboratory animals noninvasively in vivo.

Effect of long-term cholesterol-lowering treatment with HMG-CoA reductase inhibitor (simvastatin) on myocardial perfusion evaluated by thallium-201 single photon emission computed tomography

Fifteen patients with either angina pectoris or old myocardial infarction, who had positive 201Tl single photon emission computed tomography (SPECT) imaging and coronary sclerosis of more than 50%, were treated with an HMG-CoA reductase inhibitor (simvastatin) for more than 1 year. They were compared with an untreated control group (n = 25). Total cholesterol decreased 22% and high-density lipoprotein (HDL) increased 9% with simvastatin; both changes were significantly different from those in controls. Long-term simvastatin induced improvement of myocardial perfusion on 201Tl SPECT images both during exercise and at rest, which was also significantly different from controls. In addition, the improvement of myocardial perfusion on 201Tl SPECT images was clearly related to the improvements in cholesterol values, especially nonHDL cholesterol. Thus, the greater the decrease in nonHDL cholesterol, the greater the improvement in myocardial perfusion at rest or during exercise with long-term treatment using an HMG-CoA reductase inhibitor. These findings indicate that the improvements in cholesterol values caused by HMG-CoA reductase inhibitor therapy are related to improvements of myocardial perfusion seen on 201Tl SPECT images.

Immune function and psychological factors in patients with coronary heart disease (I)

As part of studies on the effects, especially the preventive effects, of exercise and psychological factors on cardiovascular diseases, the association between psychological tendencies and immune response was evaluated in patients with coronary heart disease who were receiving exercise therapy. The Pearson's product-moment correlation coefficients between natural killer (NK) cell activity and various psychological scales were obtained. For the Moudsley Personality Inventory, NK cell activity had a significant positive correlation with the extraversion scale and a significant negative correlation with the neuroticism scale. NK cell activity also had a significant positive correlation with the playful humor scale and a significantly negative correlation with the Self-rating Depression Scale. The positive correlation of NK cell activity with the extraversion scale and the humor scale and its negative correlation with the neuroticism scale suggest an association between a positive-feeling tendency and high NK cell activity. The negative correlations of NK activity with the depression scale and neuroticism scale indicate that decreased or excessive expression of feelings inhibits NK cell activity. Thus, high NK activity appears to be associated with optimal expression of feelings.

Heparin potentiates collateral growth but not growth of intramyocardial endarteries in dogs with repeated coronary occlusion

Heparin accelerates coronary collateral development in various animal models of myocardial ischemia. The purpose of this study was to clarify the beneficial effect of heparin on canine collateral development. Seventeen adult mongrel dogs were instrumented for measurements of a subendocardial segment length in the central area perfused by the left circumflex coronary artery, its flow, and left ventricular pressure. A pulsed Doppler flow probe and an externally inflatable pneumatic occluder were placed around the proximal circumflex artery. After the recovery from surgery, 2-min circumflex coronary artery occlusions were repeated eight times at 58-min intervals daily. After excluding seven dogs with well-developed preexisting collateral circulation, ten dogs were randomized into two groups with (n = 5) and without (n = 5) heparin treatment. The total occlusion time until adequate collateral development (an index of collateral growth) was 164+/-34 (SD) min in dogs with heparin treatment, being significantly less than 289+/-49 min in dogs without heparin (p<0.01). In contrast, the extent of the reduction in resting blood flow of the repeatedly occluded circumflex artery (an index of neovascularization toward the ischemic area) was comparable in dogs with and without heparin (15.4+/-12.4% vs. 21.1+/-13.6%, p=NS). Heparin promotes nonsprouting angiogenesis (arteriogenesis) of preformed collateral vessels but not neovascularization toward the ischemic area in dogs with brief repetitive coronary occlusions.

Improvement of regional myocardial and coronary blood flow reserve in a patient treated with enhanced external counterpulsation: evaluation by nitrogen-13 ammonia PET

Enhanced external counterpulsation (EECP) is a noninvasive treatment for chronic stable angina, which works by recruiting and developing the coronary collateral vessels. Coronary perfusion and coronary flow reserve (CFR) were evaluated by nitrogen-13 (13N) ammonia positron emission tomography (PET) in a patient who had undergone EECP. The patient, who had 3-vessel coronary artery disease, required a percutaneous transluminal coronary angioplasty (PTCA) for the right coronary artery. The PTCA was successful, but 6 months later he again felt chest oppression. The coronary angiography showed re-stenosis at the PTCA site, and other progressive coronary stenosis. The patient was again treated with EECP for 35 h. The 13N-ammonia PET was performed both at baseline and during dipyridamole provocation, before and after EECP treatment. Coronary perfusion of each myocardial wall increased at the baseline (anterior: 0.52-0.75; septal: 0.48-0.66; lateral: 0.61-0.68; inferior: 0.46-0.57 ml min(-1) g(-1), and the CFRs in the septal and inferior walls (septal: 2.07-2.15; inferior: 1.99-2.06) also increased after the treatment. Thus, the EECP treatment improved both coronary perfusion at baseline and CFR, which suggests that it may be one of the choices for treatment of angina.

Myocardial metabolism of 123I-BMIPP in a canine model with ischemia: implications of perfusion-metabolism mismatch on SPECT images in patients with ischemic heart disease

123I-(rho-iodophenyl)-3-R,S-methylpentadecanoic acid (BMIPP) is a fatty acid analog for SPECT imaging. This radiopharmaceutical possesses the unique property, that is, perfusion-metabolism mismatch on SPECT images in patients with ischemic heart disease. However, the reason of this mechanism remains unclear.

METHODS

Using open-chest dogs under anesthesia, we made a system to release all the blood of the great cardiac vein outside without recirculation, if necessary. Left anterior descending artery (LAD) was occluded for 30 min after reperfusion. After the injection of BMIPP into LAD, blood samplings from the cardiac vein and abdominal aorta (6 dogs) or serial biopsy specimens from the LAD region (5 dogs) were performed, and then compared with the normal control. The catabolites of BMIPP, including backdiffusion of nonmetabolized BMIPP, were evaluated with high-performance liquid chromatography (HPLC) in the efflux study. Thin-layer chromatography (TLC) technique was introduced in the tissue analytical study.

RESULTS

Although the rapid extraction of BMIPP from the plasma into the myocardium and the subsequent retention were unchanged, the early washout (8 min) of radioactivity significantly increased (51% +/- 12% to 65% +/- 7%; P < 0.05) with ischemia. The metabolites from the myocardium consisted of backdiffusion of nonmetabolized BMIPP, alpha, intermediate, and full oxidation metabolites. Among these metabolites, backdiffusion of nonmetabolized BMIPP in blood significantly increased (27.9% +/- 7.7% to 42.3% +/- 8.1%; P < 0.05), especially in the early phase with ischemia. In tissue, the radioactivity was concentrated in the triglyceride pool even in the early phase, and in addition, BMIPP and alpha-oxidized metabolite significantly decreased in the early phase with ischemia (t = 1 min after BMIPP injection, 25.9% +/- 8.6% to 14.5% +/- 2.1%, P < 0.01; t = 2 min, 8.9% +/- 5.0% to 4.5% +/- 1.7%, P < 0.05).

CONCLUSION

These results show that backdiffusion of nonmetabolized BMIPP from the myocardium increased and BMIPP (long-chain fatty acids) in tissue decreased with ischemia, suggesting backdiffusion of nonmetabolized BMIPP might play an important role in myocardial perfusion-metabolism mismatch on SPECT images in patients with ischemic heart disease.

A patient with hypertrophic cardiomyopathy accompanied by right ventricular dilation of unknown cause

Hypertrophic cardiomyopathy (HCM) is a disease characterized by an unknown cause of hypertrophy in the left or right ventricle. The dilated phase of HCM shows disease conditions resembling dilated cardiomyopathy, such as ventricular dilation, thin ventricular wall, and reduction of the ejection fraction. A patient presented with left ventricular concentric hypertrophy accompanied by right ventricular dilatation of unknown cause. Right ventricular endomyocardial biopsy specimens showed characteristic myocardial disarray. Therefore, there is the possibility that the patient had right and left ventricular HCM in the process toward the dilated phase, in which dilatation first occurred in the right ventricle.

Basic kinetics of 15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid (BMIPP) in canine myocardium

BMIPP is a radioiodinated fatty acid analogue used for myocardial single photon emission CT (SPECT) imaging based on high cardiac fatty acid metabolism. In normal dogs, 74% of the injected BMIPP was instantly extracted and was then retained in 65.3%. The washout of the retained radioactivity was low, and most of the washout was alpha- and beta-oxidation metabolites. ATP concentration plays an important role in the myocardial uptake and retention of BMIPP. The ATP-dependent BMIPP uptake at the TG pool was strongly regulated by etomoxir with modifying mitochondrial beta-oxidation and subsequent ATP production. Thus, myocardial viability was reflected on the BMIPP uptake in acute ischemia. In spite of insignificant changes in early extraction and retention. BMIPP back diffusion (r = -0.92) and full-oxidation metabolite (r = 0.78) were correlated with the severity of ischemia. Mismatched region of BMIPP with flow (Tl-201) showed decreased metabolic enzymes such as citrate synthase and 3-hydroxyacyl-CoA dehydrogenase. These data suggest that BMIPP would be feasible for detecting cellular energy state from lipid metabolism.

Effect of long-term exercise training on regional myocardial perfusion changes in patients with coronary artery disease

The cardiac rehabilitation of patients with coronary artery disease (CAD) promotes exercise tolerance, improves left ventricular function, and decreases the heart rate and systolic blood pressure at the same load intensity. Several studies have shown that cardiac rehabilitation improves myocardial perfusion in CAD patients. However, the long-term (> or = 1 year) effect of cardiac rehabilitation on myocardial perfusion is still controversial. The effect of long-term exercise training on myocardial perfusion in CAD patients was assessed using thallium-201 (201Tl) exercise studies at a baseline (4 months after the onset of CAD) and at a 1-year or more follow-up in 58 patients with stable CAD. The subjects had been divided into a training group (n=35) participating in supervised exercise 2 times per week for the follow-up period, and the control group (n=23). There was an improvement in the myocardial perfusion on stress 201Tl scintigraphy in 20 of the 35 (57.1%) trained patients and in 3 of the 23 (13.0%) of the control patients (p<0.001). The number of 201Tl stress myocardial perfusion defect segments was significantly decreased after the cardiac rehabilitation training (231 to 153 segments), but showed no change in the control group (158 to 156 segments) (p<0.01). In spite of no significant differences in the number of involved coronary arteries, it improved (12/17 patients: 70.6%) more in the patients who had trained for more than 2 years compared to the patients who had trained for less than 2 years. The exercise tolerance increased in 25 of the 35 training group patients (71.4%), and in only 3 of the 23 control group patients (13.0%). The peak double products increased from 20,131+/-6,010 to 28,370+/-5,600 (p<0.01) in the training group, and showed no change in the control group (20,567+/-5,112 to 20,964+/-7,728 (NS)). The results indicated that the long-term physical training increased exercise tolerance and the double products of CAD patients. In addition, the training resulted in improved cardiac perfusion as evidenced by 201Tl scintigraphy. The findings suggest that exercise training is an advisable and effective treatment for patients with CAD.