Effect of High Dose Statin Pretreatment on Endothelial Progenitor Cells After Percutaneous Coronary Intervention (HIPOCRATES Study)

BACKGROUND

Pretreatment with high-dose statins given before percutaneous coronary intervention (PCI) has been shown to have beneficial effects, in particular by reducing peri-procedural myocardial infarction. The mechanism of these lipid-independent beneficial statin effects is unclear. Circulating endothelial progenitor cells (EPCs) have an important role in the process of vascular repair, by promoting re-endothelization following injury. We hypothesized that statins can limit the extent of endothelial injury induced by PCI and promote re-endothelization by a positive effect on EPCs. We, therefore, aimed to examine the effect of high-dose statins given prior to PCI on EPCs profile.

METHODS

Included were patients, either statin naïve or treated chronically with low-dose statins, with stable or unstable angina who underwent PCI. Patients were randomized to receive either high-dose atorvastatin (80 mg the day before PCI and 40 mg 2-4 h before PCI) or low- dose statin. EPCs profile was examined before PCI and 24 h after it. Circulating EPCs levels were assessed by flow cytometry as the proportion of peripheral mononuclear cells co-expressing VEGFR-2+ CD133+ and VEGFR-2+ CD34+. The capacity of the cells to form colony forming units (CFUs) was quantified after 7 days of culture.

RESULTS

Twenty three patients (mean age 61.4 ± 7.4 years, 87.0% men) were included in the study, of which 12 received high-dose atorvastatin prior to PCI. The mean number of EPC-CFUs before PCI was higher in patients treated with high-dose atorvastatin vs. low-dose statins (165.8 ± 58.8 vs. 111.7 ± 38.2 CFUs/plate, respectively, p < 0.001). However, 24 h after the PCI, the number of EPC-CFUs was similar (188.0 ± 85.3 vs. 192.9 ± 66.5 CFUs/plate in patients treated with high-dose atorvastatin vs. low- dose statins, respectively, p = 0.15). There were no statistical significant differences in FACS analyses between the 2 groups.

CONCLUSIONS

The current study showed higher EPC- CFUs levels in patients treated with high-dose atorvastatin before PCI and a lower increment in EPC-CFUs after PCI. These findings could account for the beneficial effects of statins given prior to PCI, yet further investigation is required.

Acute myocardial infarction following sildenafil citrate (Viagra) intake in a nitrate-free patient

Since its introduction to the market in March 1997, sildenafil acetate (Viagra) has been prescribed to 1.7 million people. Sixteen men who were taking the drug have died, 7 of them during or soon after sexual activity. Most of these data have been derived from the media and not from the scientific literature. There is a general impression that cardiovascular complications of sildenafil occur mainly when the drug is taken concomitantly with nitrates. We describe a 65-year-old man with known coronary artery disease who had an acute myocardial infarction shortly after taking sildenafil and engaging an sexual activity. The patient had not been using nitrates. We suggest that the emotional arousal induced by Viagra, followed by the heavy physical exertion during sexual activity, triggers plaque rupture that leads to acute myocardial infarction.

[Detection of anomalous origin of left coronary artery by spiral CT as a cause of angina pectoris]

The anomalous origin of the left coronary artery can lead to angina pectoris, acute myocardial infarction or even sudden death, especially during exercise. We present a patient in whom the anomalous origin of the left coronary artery is from the right sinus of Valsalva, crossing between the aorta and the pulmonary trunk and causing ischemic chest pain. The anomaly was verified by a Spiral CT, as the coronary angiographic findings were not conclusive, particularly regarding the left course in relation to the major arteries. We suggest that Spiral CT is useful for detecting this kind of anomaly, particularly in clarifying the relationship between the left main coronary artery and the major arteries.

Coronary stenting without predilatation (SWOP): applicable technique in everyday practice

To evaluate the feasibility of stenting without predilatation, we registered all interventional procedures over a 6-month period. Six hundred patients were registered, and 684 lesions were treated. Interventions were divided into four groups: stenting without predilatation (SWOP), 221 lesions (32.4%); primary stenting with predilatation (PDS), 161 lesions (23.5%); provisional stenting (PRS), 131 lesions (19.2%); and plain-old balloon angioplasty (POBA), 171 lesions (25%). Interventional strategy was at the discretion of the operator based on few simple angiographic criteria and his clinical judgment. Procedural success was similar in all stent groups. We conclude that when primary stenting is planned, about 60% of lesions can be treated by SWOP effectively with excellent procedural results and considerable cost saving.

Terminal QRS distortion on admission is better than ST-segment measurements in predicting final infarct size and assessing the Potential effect of thrombolytic therapy in anterior wall acute myocardial infarction

We assessed predicting final infarct size (using predischarge Selvester score) by 3 electrocardiographic variables in 267 patients with first anterior wall acute myocardial infarction (AMI) undergoing (n = 86) or not undergoing (n = 181) thrombolysis. Patients with previous AMI or inverted T waves in leads with ST elevation were excluded. The sum (sigma) of ST elevation, the number of leads with ST elevation, and the initial electrocardiographic pattern were determined on the admission electrocardiogram (absence (QRS-) or presence (QRS+) of distortion of the terminal portion of the QRS in > or =2 leads (J point > or =0.5 of the R-wave amplitude in leads I, aVL, V4 to V6, or presence of ST elevation without S waves in leads V1 to V3). There was no association between sigmaST elevation and final infarct size in patients who did or did not receive thrombolytic therapy. Analysis of covariance showed that the number of leads with ST elevation (F = 19.6), thrombolysis (F = 25.2), and QRS+ initial pattern (F = 19.5) were all associated with final infarct size (p <0.0001 for all). Among patients who did not receive thrombolytic therapy, the average Selvester score was 19.7+/-9.9 for the QRS- patients and 26.1+/-10.4 for the QRS+ patients (p = 0.02). Among patients who received thrombolytic therapy, the average Selvester score was 11.7+/-9.8 for the QRS- patients and 24.2+/-10.1 for the QRS+ patients (p <0.0001). Thrombolysis reduced final Selvester score only in the QRS- group (p <0.00001), but not in the QRS+ group (p = 0.45). It is concluded that (1) final Selvester score in anterior wall AMI can be predicted by the number of leads with ST elevation, the initial electrocardiographic pattern, and thrombolysis, and (2) thrombolysis reduces final Selvester score only in patients with QRS- pattern.

Adverse cutaneous reactions to ticlopidine in patients with coronary stents

A prospective study was carried out to assess the occurrence and character of adverse cutaneous reactions in patients receiving ticlopidine hydrochloride to prevent subacute thrombosis after having undergone placement of coronary stents. During a 1-year period such patients were requested to report any adverse cutaneous reactions, and those with skin reactions were referred for dermatological evaluation. Among the 136 patients who underwent stent placement by one of the authors, 20 were referred for dermatological evaluation. Of these, 16 (11.8%) fit the case definition of ticlopidine-associated cutaneous reactions. In the first 8 consecutive patients ticlopidine was withdrawn (in 2 of these a rechallenge test was later performed); in the next 8 patients ticlopidine was not discontinued before completion of the intended 4-week period of treatment. Patients remained under weekly follow-up and underwent a weekly blood count. Skin biopsies were obtained in 5 patients with different types of eruptions. The skin reactions appeared from 2 to 21 days after commencement of ticlopidine (mean, 10 days), lasting from 2 to 30 days (mean, 5 days). Only 3 patients had other adverse effects: neutropenia in 1 and abdominal pain and nausea in 2. The most common presentations were urticaria, pruritus, and maculopapular eruption. In 3 patients there were previously unreported reactions: fixed drug eruption, erythromelalgia-like eruption, and erythema multiforme-like eruption. Of note was the rapid clearing of the skin eruption in most cases even when the drug was not withdrawn. It was concluded that adverse cutaneous reactions are relatively common in association with ticlopidine treatment but that serious reactions are rare and the disappearance of the signs and symptoms is rapid, suggesting that discontinuation of the drug is not usually imperative.

Biocompatibility of polyurethane-coated stents: tissue and vascular aspects

To assess the arterial injury triggered by polyurethane-coated vs. uncoated stents, six polyurethane-coated and six bare nitinol stents were implanted in rabbit carotid arteries. All animals were sacrificed 4 wk after stent placement. Sections were evaluated by histology and morphometric analysis. At 4 wk, both the coated and uncoated stent struts were entirely endothelialized. The spaces between the struts showed a relatively mild proliferative response, with a few sections demonstrating neovascularization around the struts. Polyurethane coating was associated with an inflammatory tissue response consisting of lymphocytic infiltration and foreign-body reaction, with the appearance of multinucleated giant cells. Lumen, intimal, and medial cross-sectional areas varied little between coated and uncoated stented vessels (2.45+/-0.19 vs. 2.47+/-0.47 mm2, 1.17+/-0.52 vs. 0.78+/-0.30 mm2, and 0.66+/-0.18 vs. 0.58+/-0.27 mm2, respectively). In the rabbit carotid artery model, polyurethane coating does not affect the degree of neointimal proliferation after endovascular stenting compared with the conventional stenting approach. However, the inflammatory tissue response may indicate a low intrinsic biocompatibility of this stable polymer, so that it may not be an ideal material for coating intravascular devices.

Long-term follow-up of a high risk cohort after stent implantation in saphenous vein grafts

OBJECTIVES

We sought to provide short- and long-term clinical outcomes of a high risk cohort treated with stents in saphenous vein grafts (SVGs).

BACKGROUND

Data on the long-term outcome of SVG stenting in high risk patients are limited.

METHODS

Johnson & Johnson stents were implanted in the SVGs of 186 patients (302 stents, 244 lesions). Ninety percent of patients presented with myocardial infarction (MI) or unstable angina (mean +/- SD ejection fraction [EF] 44 +/- 11%, patient age 71 +/- 9 years, graft age 9.4 +/- 5 years). Using a risk score classification, 155 patients (83%) were defined as high risk for repeat surgical repair or angioplasty.

RESULTS

The procedural success rate was 97.3%, with 2.7% major complications (death, Q wave MI, coronary artery bypass graft surgery [CABG]). Clinical follow-up was obtained in 177 patients (mean 19.1 +/- 13.5 months, range 7 to 59). Event rates were 10% for death; 9% for MI; 11% for repeat CABG; and 15% for repeat angioplasty (total events 45%). Kaplan-Meier estimated survival and event-free survival at 4 years were 0.79 +/- 0.06 and 0.29 +/- 0.07, respectively. Predictors of death were congestive heart failure (p < 0.01) and EF <44% (p < 0.05). Predictors of combined events of death, MI and CABG were low EF (p < 0.01) and high SVG age (>10 years, p < 0.01). There were 66 revascularization procedures (35% of patients), 24% of which were in nontarget lesions. Fifty-three percent of the cardiac events occurred during the first year of follow-up. Of the 160 survivors, 36% were free of angina, 49% were in Canadian Cardiovascular Society functional class I or II, and 15% were in class III or IV. Sixty-nine percent of patients were in class I or II according to the Specific Activity Scale, and 31% of patients were in class III or IV.

CONCLUSIONS

Balloon-expandable stent implantation in the SVGs of high risk patients is associated with a low early complication rate. Expected survival rates are good, as are the anginal and functional classifications, but there is a high rate of recurrent events and need for repeat revascularization. Vein graft stenting is an acceptable palliative option in many high risk patients.

Enhanced myocardial 18F-2-fluoro-2-deoxyglucose uptake after orthotopic heart transplantation assessed by positron emission tomography

OBJECTIVES

We sought to assess the relation between glucose metabolism, myocardial perfusion and cardiac work after orthotopic heart transplantation.

BACKGROUND

The metabolic profile of the transplanted cardiac muscle is affected by the lack of sympathetic innervation, impaired inotropic function, chronic vasculopathy, allograft rejection and immunosuppressive therapy. In relation to myocardial perfusion and cardiac work, glucose metabolism has not previously been studied in heart transplant recipients.

METHODS

Regional myocardial blood flow (ml.min-1.g-1) and 18F-2-fluoro-2-deoxyglucose (18FDG) uptake rate (ml.s-1.g-1) were measured after an overnight fast in 9 healthy male volunteers (mean age +/- SD 32 +/- 7 years) and in 10 male patients (mean age 50 +/- 10 years) who had a nonrejecting heart transplant, normal left ventricular function and no angiographic evidence of epicardial coronary sclerosis. Measurements were made by using dynamic positron emission tomography (PET) with 15O-labeled water and 18FDG, respectively. Heart rate and blood pressure were also measured for calculation of rate-pressure product.

RESULTS

18FDG uptake was similar in all heart regions in the patients and volunteers (intrasubject regional variably 12 +/- 8% and 16 +/- 12%, respectively, p = 0.51). Regional myocardial blood flow was similarly evenly distributed (intrasubject regional variability 14 +/- 10% and 12 +/- 8%, respectively, p = 0.67). Mean 18FDG uptake and myocardial blood flow values for the whole heart are given because no regional differences were identified. 18FDG uptake was on average 196% higher in the patients than in the volunteers (2.90 +/- 1.79 x 10(-4) vs. 0.98 +/- 0.38 x 10(-4) ml.s-1.g-1, p = 0.006). Regional myocardial blood flow and rate-pressure product were similarly increased in the patient group, but by only 41% (1.14 +/- 0.3 vs. 0.81 +/- 0.13 ml.min-1.g-1, p = 0.008) and 53% (11,740 +/- 2,830 vs. 7,689 +/- 1,488, p = 0.001), respectively.

CONCLUSIONS

18FDG uptake is homogeneously increased in normally functioning nonrejecting heart transplants. This finding suggests that glucose may be a preferred substrate in the transplanted heart. The magnitude of this observed increase is significantly greater than that observed for myocardial blood flow or cardiac work. In the patient group, the latter two variables were increased to a similar degree over values in control hearts, indicating a coupling between cardiac work load and myocardial blood flow. The disproportionate rise in 18FDG uptake may be accounted for by inefficient metabolic utilization of glucose by the transplanted myocardium or by the influence of circulating catecholamines, which may stimulate glucose uptake independently of changes in cardiac work load.

Sustained local drug delivery to the arterial wall via biodegradable microspheres

This study was designed to evaluate the feasibility of applying locally delivered polylactic acid microspheres for drug delivery to the arterial wall. To study drug persistence, rhodamine-loaded microspheres were infused into one carotid artery of 14 rabbits and plain rhodamine solution into the other by using a porous balloon. To study tissue response, plain microspheres and dexamethasone-loaded microspheres were infused into the carotid arteries of another group of rabbits. To study the antiproliferative effects of locally delivered drug, 20 rabbits were subjected to overstretch balloon injury to both carotid arteries and divided into 4 groups: injury alone, plain microspheres, dexamethasone-loaded microspheres, and microspheres containing colchicine and dexamethasone. Fluorescent microspheres persisted in the vessel wall for 4 wk, whereas rhodamine without microspheres disappeared at 72 h. Histopathologic studies in arteries infused with unloaded microspheres showed inflammatory cell infiltrate with polymorphonuclear cells at 1 wk and macrophages and giant cells at 4 wk. Arteries infused with dexamethasone-loaded microspheres did not show any inflammatory cell infiltrate. Local delivery of dexamethasone or dexamethasone plus colchicine did not result in significant change in the intima-to-media ratio or in residual lumen following balloon injury. Polylactic acid microspheres may be used for prolonged delivery of drugs or other bioactive agents locally to the arterial wall. They induce an inflammatory reaction that is suppressable by dexamethasone in the microspheres. Dexamethasone or dexamethasone and colchicine delivered via this system, however, failed to reduce the degree of intimal hyperplasia after overstretch balloon injury to the rabbit carotid arteries.

Temporary arterial stenting: comparison to permanent stenting and conventional balloon injury in a rabbit carotid artery model

The objective was to assess the arterial wall response to temporary stenting with a removable nitinol stent in comparison with permanent stenting and balloon injury at 28 days in the rabbit carotid artery. Restenosis remains an important limiting factor after the implantation of permanent metallic stents and balloon angioplasty. We have developed a temporary nitinol stent that uses a bolus injection of warmed saline to collapse the stent for percutaneous removal. Vascular changes related to the thermal saline bolus injection required to remove a nitinol implanted stent were assessed in 12 rabbit carotid arteries at 7 and 28 days postinjection. Nitinol stents, inflated to 3.0 mm diameter, were implanted for 3 days (n = 6) and histology and quantitative histomorphometry examined at 28 days. Results were compared with permanently implanted stents (n = 5) and balloon injury (n = 9). Dual bolus injection of 10 ml at 70 degrees C created an acute necrotizing injury and chronic neointimal proliferation, whereas injections of 5 ml at 63 degrees C were minimally injurious. Temporary stenting resulted in the least neointimal proliferation measured by the intima to media ratio (0.22 +/- 0.10 vs. 1.59 +/- 0.31 for permanent stenting and; 0.49 +/- 0.14 for balloon injury; P < 0.001). Temporary stenting maintained a significantly larger lumen than balloon (1.53 +/- 0.72 mm2 vs. 0.64 +/- 0.14 mm2; P < 0.001), which could not be explained by absolute changes in intimal cross sectional area (0.14 +/- 0.07 mm2 vs. 0.21 +/- 0.06 mm2 respectively; P = 0.33). Temporary stenting resulted in a relatively larger vessel area within the external elastic lamina than with balloon (2.28 +/- 1.06 mm2 vs. 1.30 +/- 0.18 mm2; P = 0.007). The thermal stent recovery process can create necrotizing vascular injury and neointimal proliferation at higher temperatures and injectate volumes. Stent removal after 3 days using 63 degrees C saline bolus injection results in less neointimal proliferation than with permanent stents or balloon injury. In comparison to balloon injury, temporary stenting also may have a long-lasting beneficial effect on vessel recoil and remodeling, resulting in larger lumen size after stent removal.

The outcome of patients with acute myocardial infarction ineligible for thrombolytic therapy. Israeli Thrombolytic Survey Group

PURPOSE

The aim of this study was to determine the proportion of patients with acute myocardial infarction (AMI) excluded from thrombolytic therapy on a national basis and to evaluate the prognosis of these patients by reasons of ineligibility and according to the alternative therapies that they received during hospitalization.

PATIENTS AND METHODS

During a national survey, 1,014 consecutive patients with AMI were hospitalized in all the 25 coronary care units operating in Israel.

RESULTS

Three hundred and eighty-three patients (38%) were treated with a thrombolytic agent and included in the GUSTO study. Ineligible patients for GUSTO were treated: (1) without any reperfusion therapy (n = 449), (2) by mechanical revascularization (n = 97), or (3) given 1.5 million units of streptokinase (n = 85) outside of the GUSTO protocol. The inhospital and 1-year post-discharge mortality rates were 6% and 2% in patients included in the GUSTO study; 6% and 5% in those mechanically reperfused; 15% and 10% in those treated with thromoblysis despite ineligibility for the GUSTO trial, and 15% and 13% among patients not treated with any reperfusion therapy.

CONCLUSIONS

Ineligibility for thrombolysis among patients with AMI remains high. Patients ineligible for thrombolysis according to the GUSTO criteria, but nevertheless treated with a thrombolytic agent were exposed to an increased risk.

Acute myocardial infarction entailing ST-segment elevation in lead aVL: electrocardiographic differentiation among occlusion of the left anterior descending, first diagonal, and first obtuse marginal coronary arteries

Acute myocardial infarction with ST elevation in lead aVL may represent involvement of the first diagonal or the first obtuse marginal branch. This study assesses the correlation among different electrocardiographic patterns of acute myocardial infarction with ST elevation in aVL and the site of the infarct-related artery occlusion. Patients who underwent coronary angiography within 14 days of infarction with an unequivocal culprit lesion were included. Fifty-seven patients were evaluated. The culprit lesion was in the left anterior descending coronary artery proximal to the first diagonal, first diagonal, and first obtuse marginal branches, in 38, 8, and 11 patients, respectively. ST elevation in aVL and V2 through V5 signifies left anterior descending artery occlusion proximal to the first diagonal branch (positive predictive value [PPV] and negative predictive value [NPV] of 95% and 94%, respectively). ST elevation in aVL and V2, not accompanied by ST elevation in V3 through V5, favors occlusion of the first diagonal branch (PPV, 89%; NPV, 100%). ST elevation in aVL accompanied by ST depression in V2 predicts obstruction of the first obtuse marginal branch (PPV, 100%; NPV, 98%).

Hyperdynamic performance of remote myocardium in acute infarction. Correlation between regional contractile function and myocardial perfusion

During and after myocardial infarction (MI), compensatory contractile and structural changes taking place in the remote uninvolved myocardial regions have been well described, in both experimental and clinical settings. However, quantitative information on the changes in perfusion in these regions in relation to their altered contractile function have not been available. This study was designed to assess the in vivo relationship between contractile function and perfusion in remote uninvolved hypercontractile myocardial regions, subtended by angiographically normal coronary arteries in patients with MI and single-vessel coronary artery disease. We utilized two-dimensional echocardiography and 15O-water positron emission tomography imaging to assess regional contractile function and myocardial blood flow, respectively. Measurements were performed in nine patients with single-vessel coronary artery disease and angiographically confirmed recanalization of the infarct-related artery, 1-2 days after MI (group A). Only patients demonstrating severely impaired wall motion of the infarcted area and reactive hypercontractility of the remote uninvolved regions were enrolled. Seven patients with previous non-reperfused MI (6-8 months post-MI) served as a control (group B). Systolic wall thickening and regional myocardial blood flow data sets were created for the remote myocardial segments perfused by angiographically detected patent coronary arteries by assigning regions on the tomograms to equivalent echocardiographic segments. In the remote regions, wall thickening and regional myocardial blood flow were higher in group A patients by 26% (43 +/- 6% vs 34 +/- 4%; P = 0.005) and 20% (1.06 +/- 0.15 vs 0.89 +/- 0.06 ml.g-1 per minute; P = 0.019), respectively. For both groups of patients, a significant correlation (r = 0.67; P = 0.004) between systolic wall thickening and regional myocardial blood flow was obtained. Infarcted regions in both groups showed no systolic wall thickening. In this selected group of patients these data demonstrate: (1) a proportionate increase in contractility and regional myocardial blood flow in uninvolved territories in patients with recent and old MI; (2) the in vivo relationship between contractile function and myocardial perfusion in man in these regions. When infarcted zones in both groups are equally affected, enhanced levels of catecholamines and sympathetic drive as well as different loading conditions may account for the hyperkinetic performance and consequently for the increased perfusion level in uninvolved segments in patients with recent MI.

Usefulness of a prototype directional catheter for excimer laser coronary angioplasty in narrowings unfavorable for conventional excimer or balloon angioplasty

We report clinical and angiographic results in 53 patients with 57 significant coronary or saphenous vein graft narrowings treated with directional excimer laser angioplasty. The target vessels were the left main (1%), anterior descending (32%), circumflex (19%), right coronary artery (39%), and vein grafts (9%). Lesions were morphologic class B1 (18%), B2 (79%), or C (3%), with 40 de novo and 17 restenotic lesions. Adjunctive balloon angioplasty was used in 53 lesions (93%). Mean pre- and postprocedural minimal lumen diameters were 0.6 +/- 0.3 and 1.9 +/- 0.7 mm (p < 0.001), corresponding to a mean diameter stenosis of 72 +/- 20% and 27 +/- 16%. Procedural success rate was 91%. Cumulative risk of death, Q-wave myocardial infarction, or emergency bypass operation was 9% (5 patients). Of patients who had a successful laser procedure, 28 (60%) with 30 lesions underwent angiographic follow-up at 6 +/- 3 months after the procedure. Restenosis rates (> 50% diameter restenosis or acute gain loss) were 37% and 23%, respectively. Four patients underwent bypass, 3 angioplasty, and 1 patient died from cancer. This study demonstrates the feasibility of directional application of laser energy to selected unfavorable narrowings for conventional excimer laser or balloon angioplasty. Further evaluation of this device using the now standard saline infusion technique is necessary to establish its ultimate role as a primary interventional device.

Influence of expanded balloon diameter on Palmaz-Schatz stent recoil

After successful stent implantation, the residual luminal diameter of the stented vessel is usually smaller than the maximal stent-expanded balloon diameter. The goal of this study was to determine whether immediate vessel diameter recoil after Palmaz-Schatz stenting is affected by the final expanding balloon diameter used during stent deployment. Single Palmaz-Schatz balloon expandable stents were successfully placed in 108 stenotic lesions. There were 68 patients with 75 saphenous vein graft (SVG) and 30 patients with 33 native coronary artery lesions, including 26 restenotic and 82 de novo occlusive (> 50% diameter stenosis) lesions. Quantitative coronary angiography was used for the assessment of stent recoil, defined as the difference between the minimal diameter of the fully expanded balloon and the postprocedure minimal lumen diameter divided by minimal diameter of the fully expanded balloon. A strong correlation (r = 0.94) was found between the minimal diameter of the fully expanded balloon and poststenting minimal lumen diameter. Immediate recoil was 11.3 +/- 7.5%, responsible on an average for 0.4 +/- 0.2-mm acute lumen loss. Recoil was less in SVG than in coronary arteries (9.7 +/- 6.6% vs. 14.0 +/- 7.8%; P = 0.004, and 0.3 +/- 0.2 vs. 0.4 +/- 0.2 mm; p = 0.01). Lesions were divided into four subgroups, based on the final stent expanding balloon diameter: (1) < or = 3.0 mm (n = 33); (2) > 3 < or = 3.5 mm (n = 43); (3) > 3.5 < or = 4 mm (n = 23); and (4) > 4 mm (n = 9).(ABSTRACT TRUNCATED AT 250 WORDS)

On-site catheterization laboratory and prognosis after acute myocardial infarction. Israeli Thrombolytic Survey Group

BACKGROUND

Since the introduction of thrombolytic therapy for patients with acute myocardial infarction, the use of coronary angiography has substantially increased. We sought to determine whether the presence of on-site coronary angiographic facilities influenced the utilization of coronary procedures in patients with acute myocardial infarction hospitalized in Israel's coronary care units.

METHODS

A prospective survey was conducted in January and February 1992 in the 25 coronary care units operating in Israel, 15 of which had on-site catheterization facilities. Data on demographics, clinical features, thrombolytic therapy, and the type of coronary diagnostic or therapeutic procedures performed during the current in-hospital stay were recorded. Mortality, both in-hospital and 1 year after discharge, was assessed for all patients in the survey.

RESULTS

One thousand fourteen consecutive patients with acute myocardial infarction were hospitalized during the survey, 307 (30%) of whom were admitted to 10 coronary care units without and 707 of whom were treated in hospitals with on-site coronary angiography facilities. Demographic and baseline characteristics were similar in both groups. Thrombolytic therapy was provided equally (46%) to patients admitted to hospital with and without catheterization laboratories. Patients admitted to hospitals with these laboratories underwent coronary angiography (26%) and percutaneous transluminal angioplasty and/or coronary artery bypass grafting (12%) in greater numbers than counterparts admitted to hospitals without such laboratories (10% and 5%, respectively). Hospital and cumulative 1-year mortality rates were 11% and 18%, respectively, in patients admitted to hospitals with on-site catheterization facilities vs 10% and 17%, respectively, in the patient group admitted to the other hospitals. Patients receiving thrombolytic therapy had similar hospital mortality rates unrelated to the availability of coronary catheterization laboratories.

CONCLUSION

This national survey showed that the availability of invasive coronary facilities led to increased use of diagnostic and therapeutic coronary procedures among patients with acute myocardial infarction. There was no difference in hospital or 1-year mortality rates in patients admitted to hospitals with or without on-site coronary angiographic facilities.

Stent implantation of saphenous vein graft aorto-ostial lesions in patients with unstable ischemic syndromes: immediate angiographic results and long-term clinical outcome

OBJECTIVES

This study examined the immediate angiographic and long-term clinical results of stenting saphenous vein graft aorto-ostial stenosis at a single center.

BACKGROUND

Data on the feasibility, safety and short- and long-term clinical results of stent implantation in aorto-ostial lesions in patients with unstable angina are limited.

METHODS

Palmaz or Palmaz-Schatz stents were deployed in 29 patients (mean [+/- SD] age 70 +/- 10 years) with complex (B2 or C) vein graft aorto-ostial lesion morphology. All patients had angina at rest; 23 (79%) had a previous myocardial infarction; and 13 (45%) had two previous bypass operations (mean graft age 9 +/- 5 years). Mean left ventricular ejection fraction was 42 +/- 13%.

RESULTS

Thirty-two stents were deployed in 25 new and 4 restenotic aorto-ostial lesions. Ten additional stents were implanted in five patients for eight lesions other than at ostial locations. Stent implantation was successful in all patients. There was no death, Q wave myocardial infarction, bypass surgery or stent thrombosis in the first 30 days. Stenting improved minimal lumen diameter from 0.7 +/- 0.5 mm (95% confidence interval [CI] 0.5 to 0.8) to 3.3 +/- 0.5 mm (CI 3.2 to 3.5) and percent diameter stenosis from 80 +/- 13% (CI 75% to 85%) to 1 +/- 12% (CI -3% to 6%) (p < 0.001 for both variables). Immediate loss from recoil was 0.2 +/- 0.2 mm (CI 0.2 to 0.3), corresponding to a percent recoil of 7 +/- 5% (CI 5% to 9%). Clinical follow-up in all patients at a mean of 11 +/- 8 months revealed that 27 patients (94%) were free of death or myocardial infarction. Bypass surgery and balloon angioplasty were required in one (3%) and two (6%) patients, respectively. In 21 (88%) of the remaining 24 patients, symptoms were lessened by two or more symptom classes.

CONCLUSIONS

Palmaz or Palmaz-Schatz stent implantation for saphenous vein graft aorto-ostial stenosis has a high likelihood of immediate success and is associated with a large immediate gain in lumen diameter. Thirty-day and long-term adverse event rates are low. These data suggest that stenting saphenous vein graft aorto-ostial lesions is an acceptable therapeutic option in selected elderly patients with unstable angina and large-diameter vessels.

Clinical significance and predisposing factors to symptomatic bradycardia and hypotension after percutaneous transluminal coronary angioplasty

Of 180 consecutive patients who underwent uneventful percutaneous transluminal coronary angioplasty (PTCA), 25 (13.9%) had at least 1 episode of symptomatic bradycardia and hypotension during the early postprocedure period. Symptomatic bradycardia and hypotension occurred 1 to 10 hours (mean 4 +/- 2) after PTCA. A higher incidence of symptomatic bradycardia and hypotension was found in patients receiving regular treatment with beta blockers (26% vs 10% in patients without beta blockers in their regimen, p < 0.01), diltiazem or verapamil (20% vs 9%, p < 0.025), or both a beta blocker and diltiazem or verapamil (64% vs 11%, p < 0.001). A higher incidence was also associated with angioplasty of the left anterior descending coronary artery compared with angioplasty of the other coronary arteries (22% vs 8%, p < 0.01). It is concluded that symptomatic bradycardia and hypotension is a common occurrence after PTCA. The incidence is higher after PTCA to the left anterior descending coronary artery and in patients receiving diltiazem, verapamil, and beta-blocking agents; it is particularly high in patients receiving a combination of a beta-blocking agent and either diltiazem or verapamil.

[Do on-site coronary angiographic facilities influence management and prognosis of acute myocardial infarction?]

Whether the presence of on-site coronary angiographic facilities (CAF) influences the use of invasive coronary procedures and the outcome of acute myocardial infarction in coronary care units was studied. A prospective survey was conducted early in 1992 when 1014 consecutive patients with acute infarction were admitted. Of them 707 (70%) were admitted to coronary care units of hospitals with, and 307 (30%) without CAF. Thrombolytic therapy was given to 46% in both groups. Those admitted to hospitals with CAF underwent more coronary angiographies (26%) and percutaneous transluminal angiography and/or coronary artery bypass grafting (12%) than those without CAF (10 and 5%, respectively--p < 0.005). In-hospital and 1-year mortality were 11 and 18% respectively in those with CAF, vs 10 and 11%, respectively, in those without CAF. All patients treated with a thrombolytic agent had similar mortality, unrelated to the availability of CAF. The survey showed that the availability of on-site coronary angiography facilities led to greater use of invasive coronary procedures in cases of acute myocardial infarction, but there was no significant difference in mortality.

Isolated mid-anterior myocardial infarction: a special electrocardiographic sub-type of acute myocardial infarction consisting of ST-elevation in non-consecutive leads and two different morphologic types of ST-depression

We describe eight patients with a distinct electrocardiographic pattern of anterior wall myocardial infarction characterized by three main features: (1) a pattern of 'transmural ischemia' (ST-elevation with positive T-wave) in non-consecutive leads: a VL and V2, and two different types of ST-depression; (2) a pattern of 'true reciprocal changes' (ST-depression and negative T-wave) in III and a VF; (3) a pattern of 'sub-endocardial ischemia' (ST-depression with positive T-wave) in V4-5, while ST in V3 was either isoelectric or depressed. We characterize the electrocardiographic features and correlate them with the echocardiographic, radionuclide, and angiographic data. All patients admitted to the coronary care unit from January 1990 to April 1992 with evolving acute myocardial infarction were evaluated prospectively. Patients whose admission electrocardiogram met the description above were included. The electrocardiographic evolution, echocardiographic, Technetium MIBI tomography, and coronary angiography are described. Of 471 patients with acute anterior wall myocardial infarction, admitted to the coronary care unit during the study period, eight patients met the inclusion criteria (1.7% of acute anterior wall myocardial infarction). Echocardiographic studies revealed mid-anterior hypokinesis in two patients, anterior and apical hypokinesis in one, and no wall motion abnormality in four patients. Technetium MIBI tomography, done in five patients, was consistent with mid-anterior or midanterolateral infarction without involvement of the septum or apex. Coronary angiography, performed in seven patients, demonstrated significant obstruction of the first diagonal branch in all of the patients. In four patients, the diagonal occlusion was the only significant coronary lesion in the left coronary artery.

CONCLUSION

Most of the anterior myocardial infarctions also involve the septal and apical regions. Anterior wall myocardial infarctions limited to the mid-anterior or mid-anterolateral wall, without apical or septal wall involvement are relatively rare. This study describes a special electrocardiographic form of anterior wall acute myocardial infarction. This distinct electrocardiographic pattern represents true mid-anterior wall myocardial infarction, caused by occlusion of a first diagonal branch of the left anterior descending coronary artery. The septal and apical regions are not involved because the blood supply via the left anterior descending artery is not interrupted.

Localized arterial wall drug delivery from a polymer-coated removable metallic stent. Kinetics, distribution, and bioactivity of forskolin

BACKGROUND

Coronary stenting is associated with two major complications: subacute thrombosis and neointimal proliferation resulting in restenosis. Our hypothesis is that the biocompatibility of metallic stents can be improved by coating with a polymer membrane that delivers agents that favorably modify the local arterial microenvironment. This study evaluates the kinetics, distribution, and bioactivity of the model drug forskolin delivered to the local arterial wall by a polyurethane-coated removable metallic stent.

METHODS AND RESULTS

Stents were used in rabbit carotid arteries (n = 20) for as long as 24 hours. The quantity of forskolin bound to the stent decreased exponentially with a half-life of 5.8 hours. Blood concentrations peaked at 140 +/- 39 pg/microL at 4 hours. The adjacent arterial media contained 60 +/- 39 ng/mg, which was 380- and 460-fold greater than the contralateral carotid media and the systemic blood, respectively (P < .0001). Media forskolin concentrations declined exponentially over time with a tissue half-life of 5.0 hours. Drug distributed throughout the vessel wall with decreasing gradients in the radial and axial dimensions consistent with a diffusion process. Removal of the stent was associated with a 100-fold decline in media forskolin concentration within 2 hours. Forskolin release was associated with a sustained 92% increase in carotid blood flow and a 60% decrease in local arterial resistance compared with coated control stents (P < .005). In another set of rabbits (n = 14) using a carotid crush injury, flow-reduction model, forskolin prolonged the time to flow variation and occlusion by 12-fold compared with the use of bare metal stents and 5-fold compared with the use of polyurethane-coated stents (P < .0001).

CONCLUSIONS

A polymer-coated metallic stent can deliver forskolin to the local arterial wall in high concentrations relative to the blood or other tissues. High local drug concentrations are dependent on maintaining stent-to-tissue gradients. The delivered drug is biologically active, demonstrating vasodilating and antiplatelet properties.

Implications of inferior ST-segment depression in anterior acute myocardial infarction: electrocardiographic and angiographic correlation

This study assesses the significance of inferior ST-segment depression during anterior acute myocardial infarction (AMI) by investigating the relationship between inferior ST-segment depression and (1) the site of the left anterior descending (LAD) coronary artery lesion and (2) ST-segment deviation in the various anterior and lateral leads. We studied 126 patients with anterior AMI who underwent coronary angiography within 21 days of hospitalization. The admission 12-lead electrocardiograms were evaluated for ST-segment amplitude in each lead at 0.08 second after the J-point. Coronary angiography was evaluated for the site and severity of luminal narrowing of the coronary arteries. The site of the culprit lesion in the LAD artery, relative to the origin of the first septal and diagonal branches, was determined. In four patients no lesion was identified in the LAD artery. Of the remaining 122 patients, 40 and 53 patients had a LAD artery lesion proximal to the first septal and first diagonal branches, respectively. Additional luminal narrowing (> or = 70% of diameter) was found in the circumflex and the right coronary arteries in 27 and 37 patients, respectively. ST-segment depression of > 1 mm in leads II, III, and aVF was noted in 24, 29, and 24 patients, respectively. The prevalence of a LAD artery preseptal and prediagonal lesion was higher in patients with inferior ST-segment depression.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of gender in the therapeutic management of patients with acute myocardial infarction in Israel. The Israeli Thrombolytic Survey Group

A national study was performed in early 1992 in the 25 operating coronary care units in Israel, which enabled the assessment of whether the therapeutic management of patients with acute myocardial infarction was affected by patient gender. During a 2-month period, 1,014 consecutive patients with acute myocardial infarction were hospitalized. Thrombolytic therapy was given to 47% of men (362 of 769), and 43% of women (106 of 245) (p = NS). After adjustment for age, no gender differences in the administration of thrombolytic therapy were noted (odds ratio 0.95; 95% confidence interval 0.73-1.23). Coronary angiography was more frequently performed in men (22%) than in women (16%) (p < 0.05). However, no gender differences in the use of angioplasty or coronary bypass surgery performed during the index hospitalization were found (10% in men, and 8% in women). The main reasons for ineligibility for thrombolytic therapy were: late hospital arrival, absence of qualifying ST-T changes on admission electrocardiogram, and contraindications to thrombolytic therapy. Hospital death was significantly lower in patients receiving thrombolytic therapy (37 of 456; 8%) than in those excluded from thrombolysis (70 of 540;13%) (p < 0.01). This difference was significant for men, but not for women. The 1-year postdischarge mortality was 4% in patients treated compared with 12% in those ineligible for thrombolysis (p < 0.01). This significant difference persisted among men and women.

Spontaneous hemarthrosis following thrombolytic therapy for acute myocardial infarction

We describe a 45-year-old man who developed a spontaneous hemarthrosis of his right knee following thrombolytic therapy with streptokinase and rtPA for acute myocardial infarction. Surprisingly, despite the wide use of thrombolytic therapy, only four cases of spontaneous hemarthrosis following thrombolysis have been previously reported. Prompt aspiration of the joint, after stopping anticoagulant therapy, and splinting will provide early diagnosis and may prevent further damage to the joint.

Comparison of regional myocardial blood flow in syndrome X and one-vessel coronary artery disease

Myocardial blood flow (MBF) was measured using continuous inhalation of oxygen-15-labeled carbon dioxide, and positron emission tomography before and after intravenous dipyridamole in 13 patients with syndrome X (angina pectoris, angiographically normal coronary arteries, positive exercise test and negative ergonovine test), 7 healthy subjects and 8 patients with 1-vessel coronary artery disease (CAD). In patients with syndrome X, baseline MBF was greater than in healthy subjects and patients with CAD (1.24 +/- 0.27 vs 0.87 +/- 0.07 and 1.03 +/- 0.23 ml/g/min, respectively; p < 0.05), and more heterogeneous (34 +/- 7 vs 26 +/- 5 and 25 +/- 6, respectively; p < 0.05) as assessed by the coefficient of variation among myocardial regions < or = 2.3 cm3. After dipyridamole, MBF in patients with syndrome X was similar to that in healthy subjects (2.95 +/- 0.75 vs 3.40 +/- 0.82 ml/g/min; p = NS) and greater than in patients with CAD (1.78 +/- 0.76 ml/g/min; p < 0.05). However in patients with both syndrome X and CAD, MBF was more heterogeneous than in healthy subjects (48 +/- 12 and 48 +/- 11, respectively, vs 30 +/- 7; p < 0.01). Thus, in patients with syndrome X, MBF is abnormally heterogeneous both at baseline and after dipyridamole. These findings are compatible with the presence of dynamic alterations of small coronary arteries. Because these alterations appear to be very sparse within the myocardium, they can be undetected when myocardial perfusion, function and metabolism are assessed using conventional methods that are unable to detect small myocardial regions.

"Infective" myocardial infarction

Four patients who developed acute myocardial infarction (AMI) in the setting of systemic febrile illness are described. They were all treated with anticoagulants or lytic agents (or both), demonstrating patient coronary arteries following infarction. We discuss the pathogenesis and therapeutic implications of AMI occurring in this setting.

ST segment depression in a VL: a sensitive marker for acute inferior myocardial infarction

In a substantial percentage of patients with acute myocardial infarction, especially in those with inferior wall involvement, no ST elevation is detected on the electrocardiogram. In many of them, ST depression is found in leads oriented to remote segments of the heart. The importance of those reciprocal changes for early diagnosis of acute inferior myocardial infarction in patients without ST elevation has not been stressed. In order to find the prevalence of reciprocal ST depression, we evaluated the admission electrocardiograms of 107 consecutive patients with evolving first acute inferior myocardial infarction. Ninety-three patients had ST elevation of at least 0.1 mV in at least one of the inferior leads: II, III or aVF (group A) and in 14 patients ST displacement did not reach 0.1 mV in any of these leads (group B). In both groups, reciprocal ST depression occurred more frequently in aVL than in any other lead. Only three patients had no ST depression in aVL. In eight patients (7.5%) ST depression in aVL was the sole early electrocardiographic sign of the inferior infarction. aVL is the only lead that is facing the superior part of the left ventricle and thus is the only lead that is truly opponent to the inferior wall. It seems that ST depression in aVL, by contrast to that in the precordial leads, is found in the majority of patients with evolving inferior wall myocardial infarction and is not influenced by extension of the infarction to the right ventricle or to the posterior wall.(ABSTRACT TRUNCATED AT 250 WORDS)

The significance of a dipyridamole induced 99mTc-MIBI perfusion abnormality on single photon emission tomography: a quantitative validation with labelled water and positron emission tomography

To relate technetium-99m 2-methoxy-isobutyl-isonitrile (99mTc-MIBI) uptake to regional myocardial blood flow (rMBF), 99mTc-MIBI single photon emission tomography (SPET) and H2(15)O positron emission tomography (PET) scans were obtained at rest and after dipyridamole infusion in six patients with single vessel coronary artery disease. 99mTc-MIBI and H2(15)O data sets were created for each segment perfused by the stenotic vessel and for a normal reference area, assigning regions on the SPET tomograms to comparable regions on the PET by similar transaxial image reconstructions. All patients demonstrated post-dipyridamole 99mTc-MIBI perfusion defects in the territories supplied by the stenotic arteries. Resting rMBF in these regions was slightly lower than that in the normal areas (0.82 +/- 0.05 vs 0.90 +/- 0.09 ml/g/min, P = NS). A 43% +/- 14% reduction in 99mTc-MIBI activity in the area at risk was coupled with on average a 60% +/- 9% reduction in post-dipyridamole rMBF compared with control regions (0.98 +/- 0.08 vs 2.52 +/- 0.51 ml/g/min, P < 0.001). Thus, SPET assessment of 99mTc-MIBI uptake tends to underestimate the perfusion contrast between areas with normal and areas with low coronary vasodilatory reserve when compared to PET. However, these findings may still not affect the clinical usefulness of 99mTc-MIBI and more extensive studies are required to confirm these results in the clinical environment.

The incidence of atrial arrhythmias during inferior wall myocardial infarction with and without right ventricular involvement

The atrial arrhythmia profile during inferior wall acute myocardial infarction (AMI) has not been systematically examined with respect to right ventricular (RV) involvement. To this end, 62 consecutive patients with first inferior wall AMI and no other conditions known to increase susceptibility for rhythm disturbances were studied by 24-hour Holter monitoring during the first and tenth day of infarction. Based on radionuclear ventriculography performed on day 2 of infarction, patients were allocated to two groups: group A--36 patients (58%) with right ventricular ejection fraction (RVEF) less than 40% (mean +/- SD, 31 +/- 6%) and group B--26 patients (42%) with normal (greater than 40%) RVEF (mean +/- SD, 47 +/- 5%). There were no significant differences between the two groups with respect to age, sex, or left ventricular (LV) function. In the group as a whole, ectopic activity in the different categories of atrial arrhythmias was significantly higher during the first day than on the tenth day of infarction. Comparing the two groups, 33 patients (92%) in group A had a mean hourly frequency of one or more atrial premature contractions (APCs) during the first day of infarction compared with 18 patients (69%) in group B (p less than 0.001). Atrial and supraventricular tachycardia were recorded more frequently in group A patients (16 of 36 [44%] versus 8 of 26 [31%]) as well as atrial fibrillation (AF) (7 of 36 [19%] versus 1 of 26 [4%]). Quantitative analysis showed a similar trend for a higher rate of ectopic events in group A patients. Ectopic activity was neither influenced by LVEF nor by age or sex.(ABSTRACT TRUNCATED AT 250 WORDS)

A new strategy for the assessment of viable myocardium and regional myocardial blood flow using 15O-water and dynamic positron emission tomography

BACKGROUND

We have developed a new measure of myocardial viability, the water-perfusable tissue index (PTI), which is calculated from transmission, C15O, and H2(15)O positron emission tomography (PET) data sets. It is defined as the proportion of the total anatomical tissue within a given region of interest (ROI) that is capable of rapidly exchanging water and has units g (perfusable tissue)/g (total anatomical tissue). The aim of this study was to assess the prognostic value of PTI in predicting improvement in regional wall motion after successful thrombolysis for acute myocardial infarction (AMI) and to measure the myocardial blood flow to the perfusable tissue (MBFp, ml/min/g [perfusable tissue]). Furthermore, PTI was compared with 18FDG metabolic imaging in patients with old myocardial infarction (OMI).

METHODS AND RESULTS

PET scans were performed in healthy volunteers (group 1, n = 8), patients with OMI (group 2, n = 15), and in patients who were successfully thrombolysed after an AMI (group 3, n = 11). Systolic wall thickening was measured by two-dimensional echocardiography within 2-4 days of AMI and after 4 months to assess contractile recovery. In the healthy volunteers, MBFp was 0.95 +/- 0.13 ml/min/g (perfusable tissue). PTI in these regions was 1.08 +/- 0.07 g (perfusable tissue)/g (total anatomical tissue), which was consistent with all normal myocardium being perfusable by water. In the OMI group, the ratio of the relative 18FDG activity to the relative MBFp defect (metabolism-flow ratio) was calculated for each asynergic segment. Regions in which the metabolism-flow ratio was greater than or equal to 1.20 were considered reversibly injured, whereas those in which the ratio was less than 1.20 were deemed irreversibly injured. PTI in the former group of regions (n = 9) was 0.75 +/- 0.14 g (perfusable tissue)/g (total anatomical tissue) and was significantly higher than in irreversibly injured regions (n = 6) (0.53 +/- 0.12 g [perfusable tissue]/g [total anatomical tissue], p less than 0.01). Values of MBFp were similar in these segments. Seven of 12 segments in the AMI patients showed improved systolic wall thickening on follow-up. PTI in these recovery segments was 0.88 +/- 0.10 g (perfusable tissue)/g (total anatomical tissue) (p = NS versus control). PTI in the nonrecovery regions was 0.53 +/- 0.11 g (perfusable tissue)/g (total anatomical tissue), which was similar to the segments in group 2 in which 18FDG uptake was absent. MBFp was similar in both the recovery and nonrecovery segments in the subacute phase.

CONCLUSIONS

These data indicate that PTI may be a good prognostic indicator for the recovery of contractile function after successful thrombolysis and show that myocardial viability may be assessed by PET without metabolic imaging.

Ventricular tachycardia of right bundle-branch block--left axis deviation morphology and organic heart disease

Most series of patients with ventricular tachycardia (VT) of right bundle-branch block (RBBB)-left axis deviation (LAD) morphology include young individuals with no overt evidence of structural heart disease. In the present report, the clinical and electrophysiologic findings in two patients with verapamil-responsive VT and organic heart disease are described.

Electrocardiographic Q-waves inconstancy during thrombolysis in acute anterior wall myocardial infarction

It is the purpose of this paper to describe the electrocardiographic inconstancy of Q-waves during administration of thrombolytic therapy. This was documented in four patients given streptokinase early in the course of anterior wall myocardial infarction. Understanding the pathogenesis of sequential dynamic variations of Q-waves in this setting may offer important insights into coronary physiology and management of acute coronary events. We discuss the possible explanations for such changes with respect to tissue viability, dynamic vascular changes and electrophysiological properties of the reperfused infarcted myocardium.

S-T segment depression in right-sided precordial leads during acute inferior wall infarction

Right-sided chest leads (V3-V4R) were recorded in the early stages of first inferior wall acute myocardial infarction (AMI) in 100 consecutive patients. Nine patients (9%) presenting with S-T segment depression (greater than 1 mm) in these leads were subsequently studied by echocardiography and radionuclear angiography. In this group, there were 5 patients with intact right ventricular (RV) function and 4 other patients with clinical findings compatible with RV infarction. We suggest that one should not rule out RV involvement when S-T segment depression rather than elevation is seen in the right precordial leads in the presence of inferior wall AMI. An individual assessment for RV infarction is recommended when this pattern is apparent on the ECG.

Dipyridamole vasodilator response after human orthotopic heart transplantation: quantification by oxygen-15-labeled water and positron emission tomography

To assess coronary vasodilator reserve after orthotopic heart transplantation, regional myocardial perfusion was measured with oxygen-15-labeled water and dynamic positron emission tomography in 14 cardiac allograft recipients who were not experiencing rejection and who had no angiographic evidence of epicardial coronary sclerosis 15 to 73 months (mean +/- SD 43 +/- 19) after transplantation (group I). Twelve normal men with an average age of 31 years (group II) served as a control group. Regional perfusion was measured at rest and after the intravenous administration of 0.6 mg/kg body weight of dipyridamole. Rest regional myocardial blood flow was homogeneously distributed throughout the left ventricle and was significantly higher in transplant recipients (mean 1.16 +/- 0.26 ml/g per min [range 0.8 to 1.73] than in normal subjects (mean 0.85 +/- 0.13 ml/g per min [range 0.57 to 0.99]; p = 0.001) as was rest heart rate-systolic blood pressure product (rate-pressure product 11,255 +/- 2,540 vs. 7,073 +/- 1,306; p less than 0.001). After dipyridamole, perfusion in the transplant recipients was homogeneous and slightly lower (2.73 +/- 1.03 vs. 3.40 +/- 1.09 ml/g per min; p = NS), whereas rate-pressure product was slightly higher (12,179 +/- 2,266 vs. 10,885 +/- 1,895; p = NS) than the value in normal subjects. Dipyridamole vasodilator response (dipyridamole/rest myocardial blood flow) ranged from 1.23 to 4.92 (mean 2.50 +/- 1.13) in group I and from 2.65 to 5.45 (3.97 +/- 0.89) in group II (p = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Prazosin's effect in high renin hypertension complicating pheochromocytoma

During three consecutive days of prazosin treatment in a patient with pheochromocytoma, urinary catecholamine metabolite levels were correlated with plasma renin activity. Suppression of renin plasma activity resulted in sustained hemodynamic and clinical improvement, while no remarkable changes were observed in urinary catecholamine metabolite levels. This suggests that prazosin may interrupt the vicious cycle of worsening hypertension provoked by further activation of the renin-angiotensin system mediated by excessive circulating catecholamines.

Head-up tilt for the evaluation of syncope of unknown origin in children

Fifteen patients aged 10 to 18 years with syncope of unknown origin, and 10 healthy control children aged 11 to 18 years, were evaluated by head-up tilt to 60 degrees for 60 minutes. Six patients (43%) reproduced symptoms of syncope during the examination. Four had a typical vasovagal reaction; two had marked hyperventilation. None of the children in the control group had syncope. The head-up tilt test offers a simple, noninvasive, high-yielding diagnostic tool for evaluation of syncope in children.

Noninvasive quantification of regional myocardial blood flow in coronary artery disease with oxygen-15-labeled carbon dioxide inhalation and positron emission tomography

BACKGROUND

Oxygen-15-labeled water is a diffusible, metabolically inert myocardial blood flow tracer with a short half-life (2 minutes) that can be used quantitatively with positron emission tomography (PET). The purpose of this study was to validate a new technique to quantify myocardial blood flow (MBF) in animals and to assess its application in patients.

METHODS AND RESULTS

The technique involves the administration of 15O-labeled carbon dioxide (C15O2) and rapid dynamic scanning. Arterial and myocardial time activity curves were fitted to a single tissue compartment tracer kinetic model to estimate MBF in each myocardial region. Validation studies consisted of 52 simultaneous measurements of MBF with PET and gamma-labeled microspheres in nine closed-chest dogs over a flow range of 0.5-6.1 ml/g/min. A good correlation between the two methods was obtained (y = 0.36 + 1.0x, r = 0.91). Human studies consisted of 11 normal volunteers and eight patients with chronic stable angina and single-vessel disease, before and after intravenous dipyridamole infusion. In the normal group, MBF was homogeneous throughout the left ventricle both at rest and after administration of dipyridamole (0.88 +/- 0.08 ml/g/min and 3.52 +/- 1.12 ml/g/min, respectively; p less than or equal to 0.001). In patients, resting MBF was similar in the distribution of the normal and stenotic arteries (1.03 +/- 0.23 and 0.93 +/- 0.21 ml/g/min, respectively). After dipyridamole infusion, MBF in normally perfused areas increased to 2.86 +/- 0.83 ml/g/min, whereas in the regions supplied by stenotic arteries it increased to only 1.32 +/- 0.27 ml/g/min (p less than or equal to 0.001).

CONCLUSIONS

PET with C15O2 inhalation provides an accurate noninvasive quantitative method for measuring regional myocardial blood flow in patients.