Adjunctive therapies in the cath lab. Successful medical therapy of left main thrombosis: value of serial coronary angiography

Acute coronary syndromes (ACS), including unstable angina, non-Q wave myocardial infarctions (MI) and Q-wave MIs, are usually the result of plaque rupture and subsequent thrombus formation. Commonly, patients with ACS have significant underlying coronary artery disease (CAD) demonstrable by coronary angiography and are candidates for prompt revascularization. In many cases, however, ACS are due to coronary thrombosis in the absence of obstructive CAD and therefore aggressive medical therapy may be sufficient. Coronary angiography is an invaluable resource for individualized treatment decisions. We describe a patient with thrombosis of the left main coronary artery successfully treated with aggressive and prolonged antiplatelet and anticoagulant therapy under the guidance of serial coronary angiography.

Elevated interleukin-6 levels in patients with asymptomatic left ventricular systolic dysfunction

BACKGROUND

Elevated interleukin-6 (IL-6) levels are present in patients with New York Heart Association (NYHA) class III and IV congestive heart failure (CHF) and are associated with a poor prognosis. We sought to determine whether elevated IL-6 levels are also present in patients with left ventricular (LV) dysfunction but without clinical symptoms.

METHODS

Blood samples were obtained from the femoral artery of 58 patients who underwent cardiac catheterization for recognized clinical indications. In a subgroup of 44 patients, samples were also obtained from the femoral vein, the left main coronary artery, and the coronary sinus. Patients with prior coronary artery bypass surgery, recent acute coronary syndrome, or steroid therapy were excluded. All samples were obtained before heparin or contrast administration. IL-6 was measured by enzyme-linked immunosorbent assay and values are expressed in picograms per milliliter.

RESULTS

Three groups of patients were identified: controls, no CHF, LV ejection fraction >/=0.55 (n = 32); asymptomatic LV systolic dysfunction, no CHF, LV ejection fraction <0.55 (n = 14); and CHF, pulmonary edema (n = 12). IL-6 levels were higher at all sampling sites in both the asymptomatic LV systolic dysfunction and CHF groups compared with controls with the IL-6 levels inversely related to LV ejection fraction.

CONCLUSIONS

Elevated IL-6 levels are present in patients with LV dysfunction even in the absence of the clinical syndrome of CHF. These data suggest that IL-6 may be involved in the progression of subclinical LV dysfunction to clinical CHF. IL-6 may be a marker of patients at risk for progression to clinical CHF or a novel target for therapeutic intervention.

Sites of interleukin-6 release in patients with acute coronary syndromes and in patients with congestive heart failure

This study examines the source of elevated interleukin-6 (IL-6) levels in patients with acute coronary syndrome (ACS) and congestive heart failure (CHF). IL-6 is elevated in the peripheral blood of patients with ACS and CHF, but it is not known if this proinflammatory cytokine is from a cardiac or extracardiac source. Blood samples were obtained from the femoral artery, femoral vein, left main coronary artery, and coronary sinus in 57 patients during cardiac catheterization. IL-6 levels from 12 patients with ACS and 12 patients with CHF were compared with the IL-6 levels in 33 patients who had neither of these clinical conditions. Median IL-6 levels in the peripheral and coronary circulation were a minimum fivefold higher in patients with ACS or CHF relative to control patients. An elevated transcardiac IL-6 gradient (coronary sinus-left main level) was present in patients with ACS (median 5.2; 25th and 75th percentiles 3.9 and 29.3 pg/ml, respectively) compared with control patients (median 0, -0.7 and 0.5 pg/ml; p < 0.001), but not in patients with CHF (median 0.4, -0.7 and 3.5 pg/ml; p = NS). Elevated IL-6 levels in patients with ACS derive from a cardiac source, presumably from "inflamed" coronary plaques and areas of myocardial necrosis, whereas elevated levels in patients with CHF are most likely the result of extracardiac production.

Effect of sex, hemodynamics, body size, and other clinical variables on the corrected thrombolysis in myocardial infarction frame count used as an assessment of coronary blood flow

BACKGROUND

Compared with the conventional Thrombolysis In Myocardial Infarction (TIMI) flow grade system, the corrected TIMI frame count (CTFC) quantifies coronary blood flow in a more reproducible fashion. The purpose of this study was to determine if the CTFC is affected by sex, body size, hemodynamics, or other selected clinical variables.

METHODS AND RESULTS

CTFC was measured in 534 coronary arteries from 200 consecutive patients referred for coronary angiography. CTFC in each artery was related to patient variables (sex, age, race, and body surface area), clinical variables (cardiac rhythm, medication use, diabetes, hypertension, hypercholesterolemia, smoking, and left ventricular hypertrophy), angiographic variables (wall motion abnormality in each coronary artery distribution, left ventricular ejection fraction, percent stenosis in the artery, and presence of collaterals), and hemodynamic variables (aortic systolic and diastolic blood pressure and left ventricular end-diastolic pressure). By multivariate analysis, CTFC in all arteries was significantly associated with aortic systolic and diastolic pressures and body surface area. In addition, there were significant associations between CTFC and age and sex in some but not all arteries. Although significant, the absolute change in CTFC associated with these variables was small.

CONCLUSIONS

CTFC provides a quantitative assessment of coronary blood flow that varies only a small amount in association with body size, systemic arterial pressure, age, and sex.

Preoperative factors predisposing to early postoperative atrial fibrillation after isolated coronary artery bypass grafting

An analysis of 183 patients in sinus rhythm who underwent coronary artery bypass grafting was conducted to determine the association of multiple preoperative factors, including an elevated left ventricular end-diastolic pressure, with early postoperative atrial fibrillation. An association with advanced age, a history of atrial fibrillation, and preoperative digoxin use was found, but not with an elevated left ventricular end-diastolic pressure, irrespective of left ventricular systolic function.

Effects of an ionic and nonionic contrast agent on von Willebrand factor assessed during coronary angiography

This study shows an increase in von Willebrand factor antigen in blood collected from the coronary sinus shortly after coronary angiography with an ionic contrast agent (diatrizoate), but not a nonionic contrast agent (iohexol). These findings suggest that ionic contrast agents may cause more endothelial injury than nonionic contrast agents.

Effect of estrogen replacement therapy on corrected thrombolysis in myocardial infarction frame count

The effect of chronic estrogen replacement therapy on the corrected Thrombolysis In Myocardial Infarction trial frame count of the left anterior descending coronary artery was assessed in 122 postmenopausal women. With use of multivariate analysis to account for confounding variables likely to affect the corrected Thrombolysis In Myocardial Infarction trial frame count, no chronic effect of estrogen replacement therapy on coronary blood flow was documented.

Lessons learned from the review of cardiac catheterization laboratories: a report from the Laboratory Survey Committee of the Society for Cardiac Angiography and Interventions

The Laboratory Survey Committee of the Society for Cardiac Angiography and Interventions was created as a resource for physicians and administrators to provide comprehensive independent outside review services for cardiac catheterization laboratories. Since 1989, when the committee began its work, surveys of 23 catheterization laboratories have been completed. Our review of this experience identified several recurring problems among the laboratories. The purpose of this paper is to summarize our experience and highlight the lessons we learned in the hope that this information will benefit many other laboratories.

Alterations in fibrin detected in coronary sinus blood after heparin and coronary angiography with a nonionic contrast agent (iohexol)

Although heparin and some radiographic contrast agents inhibit coagulation, thrombi can still form in their presence. The chemical environment in which a thrombus forms affects fibrin structure that may alter the ability of the thrombus to be lysed. Therefore, we assessed changes in fibrin structure in 13 patients referred for coronary angiography. Blood was obtained from the femoral vein, femoral artery, ascending aorta, left main coronary artery (LMCA), and coronary sinus (CS) before, during, and after coronary angiography was performed with iohexol. The number of fibrin monomers per fiber cross section was determined by turbidity measurements of fibrin gels formed from plasma samples. At baseline there was no difference in the number of fibrin monomers per fiber cross section in plasma gels generated from the different sampling sites. After iohexol administration, there was a significant decrease in the number of fibrin monomers per fiber cross section at the sampling sites ranging from - 13% to -25% compared with the respective baseline values with the largest change in the LMCA CS (51+/-16 to 38+/-15, p <0.025). Transcardiac (LM - CS value) changes in the number of fibrin monomers per fiber cross section were dependent on the timing of the sample collection in the CS. In 7 patients, the CS sample was collected approximately 2 minutes after injection of contrast material and there was no transcardiac difference. When the CS sample was obtained during contrast injection (n=6) a large transcardiac change occurred (44+/-10 to 32+/-14, p=0.01). These data show transient changes in fibrin structure during coronary angiography with iohexol. The thinner fibers formed in the presence of iohexol were more resistant to fibrinolysis.

Assessment of platelet activation by coronary sinus blood sampling during balloon angioplasty and directional coronary atherectomy

Three markers of platelet activation (platelet-derived microparticles, fibrinogen binding and expression of P-selectin) were assessed by flow cytometry during diagnostic coronary angiography and therapeutic coronary interventions. In 24 patients undergoing diagnostic angiography, blood was collected to determine if our sampling techniques or coronary angiography caused platelet activation. Changes during diagnostic angiography were used to establish baseline values and interpret changes during coronary interventions. In 21 patients, blood samples were obtained at 5 time points during percutaneous transluminal coronary angioplasty (PTCA) (n = 17) or directional coronary atherectomy (DCA) (n = 4). During coronary interventions, mean values for the percentage of platelets expressing P-selectin or binding fibrinogen increased, but with considerable variation among patients. Individual responses for platelet activation markers in each patient were characterized using a twofold increase to indicate elevation related to the intervention. Patients were classified as having complicated or uncomplicated procedures based on the presence of acute closure, dissection, or thrombus observed by angiography. There were no differences in the percentage of elevated markers between patients with uncomplicated (12.5%) and complicated (19%) PTCA procedures. However, patients treated with DCA had more elevated markers (38%) than those treated with PTCA (15%) (p = 0.04). Our data suggest that the extent of platelet activation in individual patients cannot be predicted by common angiographic findings or complications. More markers of platelet activation were present after DCA and may reflect a greater degree of vascular trauma associated with this procedure.

Care of the patient and management of complications after percutaneous coronary artery interventions

Certain aspects of patient management are common with conventional balloon angioplasty and newer coronary artery interventions. These aspects include the evaluation of chest pain or treatment of acute vessel closure shortly after the intervention, management of the vascular access site (especially if complications occur), prevention and treatment of contrast-induced renal dysfunction, and the use of anticoagulant or antiplatelet agents after the procedure. However, some aspects of management vary among techniques. Several different drug therapies are indicated after these procedures, but pharmacologic therapy for restenosis has been largely unsuccessful. Placement of an intracoronary stent decreases the frequency of restenosis and subsequent revascularization procedures, and functional testing may be of value in some patients after coronary artery interventions. It is important for the specialist in internal medicine to have a firm working knowledge of the various aspects of care that are required because their role in management is increasing.

Treatment of coronary artery disease in an anomalous coronary artery by placement of an intracoronary stent

We report the use of coronary stenting to treat disease in an anomalous coronary artery. The patient had a single coronary artery with anomalous left anterior descending artery arising from the right sinus of Valsalva and coursing between the aorta and pulmonary artery. Although balloon angioplasty has been used in patients with anomalous coronary arteries, this is the first report of stent placement in this circumstance.

Absence of human herpesvirus 8 genomes in coronary atherosclerosis in immunocompetent patients

Human herpevirus 8 (HHV8) has been localized to the endothelial and spindle cells of KS, suggesting a role for HHV8 in atherosclerosis. None of the 38 coronary atherectomy specimens contained HHV8 with both sensitive nested PCR assays, making it unlikely that persistent viral infection with HHV8 plays a role in coronary atherogenesis in the general population of the United States.

Randomized trial of recombinant platelet factor 4 versus protamine for the reversal of heparin anticoagulation in humans

BACKGROUND

Protamine reverses heparin anticoagulation, but it can have important side effects. We compared the safety and effectiveness of intravenous recombinant platelet factor 4 (rPF4) as an alternative to protamine in a randomized blinded trial.

METHODS AND RESULTS

In 81 patients having diagnostic cardiac catheterization, baseline hemodynamics were measured after a 5000-U bolus of heparin. Repeat measurements were obtained at the end of the procedure, and the anticoagulation status was determined by an activated coagulation time (ACT) and activated partial thromboplastin time (aPTT). Patients then received either protamine (50 mg IV over 10 minutes) or rPF4 (1.0 mg/kg IV over 2 minutes) in a blinded fashion. Serial measurements of hemodynamic and clotting functions were performed 5, 10, 20, and 30 minutes after drug administration. Follow-up measurements and clinical assessments were made at 1, 4, 6, and 24 hours later and after 7 days. Before drug administration, ACTs, aPTTs, and hemodynamics were similar among the groups. After drug infusion, there was no difference in ACT between the protamine and rPF4 patients. At 20 and 30 minutes after drug infusion, ACT and aPTT were slightly higher in those receiving rPF4, but these changes were small and of no clinical significance. There were no clinically meaningful differences in any of the hemodynamic variables between the groups, and there were no serious side effects in any patient.

CONCLUSIONS

At the dose used in this study, rPF4 was well tolerated and reversed the anticoagulant effect of heparin. These data support its continued evaluation as an alternative to protamine after cardiac surgery.

Variable influence of heparin and contrast agents on platelet function as assessed by the in vitro bleeding time

Both heparin and contrast agents have anticoagulant effects which are well-documented but their effects on platelets are not well-characterized. The purpose of the present study was to evaluate the sequential effects of heparin and then a contrast agent on platelet function during an angiographic procedure. Blood samples from 54 patients were obtained at baseline, after a 5000 unit bolus of heparin and after administration of a contrast agent (iohexol, n = 30: diatrizoate, n = 24) during angiography. The in vitro bleeding time (IVBT) was determined on nonanticoagulated whole blood using a hollow fiber device under physiological flow conditions. Mean IVBT at baseline was 3.6 +/- 2.7 minutes and increased to 17.0 +/- 12.3 minutes after heparin (p < 0.01). After heparin, 44.5% of the patients still had a normal IVBT (< 9.0 minutes), 11% of the patients had a moderately increased IVBT and the remaining patients had a large increase in their IVBT. When contrast was given (167 +/- 52 mls) following heparin, mean IVBT was higher in those who received diatrizoate (23.3 +/- 9.4 minutes) compared with iohexol (15.0 +/- 10.9 minutes, p < 0.05). However, 15 patients (28%) continued to have a normal IVBT after contrast and of these 80% had received iohexol.

Reversal of heparin anticoagulation by recombinant platelet factor 4 in humans

BACKGROUND

Protamine is used to reverse the anticoagulant effects of heparin, but it can have important side effects. Platelet factor 4 (PF4) is a protein found in platelet alpha granules that binds to and thereby neutralizes heparin. We evaluated the safety and effectiveness of intravenous recombinant PF4 to neutralize heparin anticoagulation after cardiac catheterization in a phase 1, open-label trial.

METHODS AND RESULTS

The study group consisted of 18 patients having diagnostic cardiac catheterization. Heparin (5000 U) was given after vascular access was obtained. In the first 12 patients, additional heparin was given at the conclusion of the procedure so that all patients had activated coagulation times > 300 seconds before rPF4 was given. Three patients each received 0.5, 1.0, 2.5, or 5.0 mg/kg rPF4 over a period of 3 minutes at the conclusion of the catheterization procedure. In 6 additional patients, extra heparin was not given at the conclusion of the procedure, and 1.0 mg/kg rPF4 was given. Hemodynamic measurements, cardiac output, and serial blood tests were performed 5, 10, 20, and 30 minutes after rPF4 and then into the next 24 hours. There were no serious side effects in any patient, despite transient rPF4 levels as high as 14,870 ng/mL in the patients receiving 5.0 mg/kg. One patient receiving 2.5 mg/kg had a slight transient rise in liver enzymes possibly related to the rPF4. There were no important hemodynamic effects of rPF4 administration at any dose used. Doses of 2.5 and 5.0 mg/kg were uniformly effective in reversing the anticoagulant effect of heparin. At lower doses, rPF4 neutralized the effects of heparin in most but not all patients. Pharmacokinetic analysis suggested a monophasic and one-compartment clearance of the PF4-heparin complex. No neutralizing factors to rPF4 were detected in the samples collected 7 days after dosing.

CONCLUSIONS

rPF4, in doses ranging from 0.5 to 5.0 mg/kg over 3 minutes, had no serious side effects. Given in sufficient amounts, rPF4 can completely and rapidly reverse the anticoagulant effects of heparin.

Impairment of fibrinolysis by streptokinase, urokinase and recombinant tissue-type plasminogen activator in the presence of radiographic contrast agents

OBJECTIVES

The purpose of this study was to determine whether an adverse interaction exists between radiographic contrast agents and thrombolytic drugs.

BACKGROUND

Coronary thrombosis may occur in the setting of unstable angina and after coronary angioplasty. However, the use of thrombolytic drugs in the setting of unstable angina has not been beneficial and, in one large trial of angioplasty in patients with unstable angina, was associated with an increased incidence of ischemic complications and abrupt closure. The reasons for these results are not clear. Coronary arteriography was performed in many of these trials, and it is known that fibrin structure and assembly are altered by radiographic contrast agents.

METHODS

Blood samples were obtained from patients before (n = 25) and after (n = 20) angiography using iohexol. Blood samples obtained before angiography were tested for response to streptokinase (10 and 100 IU/ml), urokinase (100, 200 and 500 IU/ml) and recombinant tissue-type plasminogen activator (rt-PA) (100 and 1,000 IU/ml) and the results measured. Iohexol, diatrizoate or ioxaglate (4% by volume) was added to separate aliquots of the baseline sample, and the test was repeated. Blood samples obtained after angiography were tested in a similar manner.

RESULTS

The onset of lysis at baseline by rt-PA at 1,000 IU/ml occurred at 72 +/- 8.2 s (mean +/- SD) and was markedly delayed in the presence of diatrizoate (527 +/- 181.7 s, p < 0.001) or iohexol (460 +/- 197.0 s, p < 0.001) but not ioxaglate. At 100 IU/ml, there was no lysis detected with rt-PA after the addition of any contrast agent. The addition of a contrast agent caused similar delays in the onset of lysis by urokinase and streptokinase; similar to rt-PA, the effect was smaller at higher concentrations of drug. In vivo blood samples obtained from the patient after angiography showed delays in the onset of lysis by rt-PA and urokinase but not streptokinase.

CONCLUSIONS

These data demonstrate that radiographic contrast agents impede fibrinolysis. This previously undescribed interaction was demonstrated using an in vitro test system, but these findings may have clinical relevance when thrombolytic drugs are used at the time of angiography.

Differences in clot lysis among patients demonstrated in vitro with three thrombolytic agents (tissue-type plasminogen activator, streptokinase and urokinase)

This study compares the ability of 3 thrombolytic drugs to promote clot lysis using a new in vitro testing procedure. Whole blood samples from 132 patients were tested using 5 different concentrations of tissue-type plasminogen activator (t-PA), streptokinase (SK) and urokinase. A mixture of blood and thrombolytic drug was placed on a dry-reagent test card containing reptilase, buffers and paramagnetic particles where clot formation occurred. Analysis of the motion of the clot-embedded paramagnetic particles caused by an oscillating magnetic field was used to define the lysis onset time. The slope of the linear regression plot of lysis onset time versus 1/[drug concentration] defined the kinetic rate constant (k) for each drug in each patient. Higher values of k indicated greater resistance to in vitro clot lysis. In the patients studied, there was a large range of k values for t-PA and SK (coefficient of variation 143 and 137%, respectively) but a smaller range of k for urokinase (coefficient of variation 32%). The coefficients of variation for t-PA and SK observed in the study group were five- to 10-fold greater than the coefficients of variation determined for replicate test measurements. Resistance to all SK concentrations tested was found in 9% of the patients. In vitro sensitivity to thrombolysis was compared among the drugs by correlating the derived k values. These comparisons indicated no relation for any of the drugs; many patients had a relatively low k value for 1 drug, while having a relatively high k value for a different drug.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of an anterior wall motion abnormality on the results of single-plane and biplane left ventriculography

Although the biplane area-length method would be optimal for all left ventriculograms, 2 contrast injections are needed in laboratories with single-plane imaging equipment. The purpose of this study was to develop practical guidelines to identify the need for biplane left ventriculography in laboratories with single-plane equipment. From a retrospective analysis of 91 consecutive biplane ventriculograms (group 1), guidelines were identified that predicted when the ejection fraction calculated by the biplane method would differ significantly from the single-plane value. These guidelines were derived from information immediately available to the operator in the laboratory at the time of the procedure. Patients in group 1 were divided into 3 subgroups: biplane exceeding single-plane ejection fraction by greater than or equal to 0.05 (n = 20); single-plane exceeding biplane ejection fraction by greater than or equal to 0.05 (n = 14); and ejection fractions within +/- 0.04 by the 2 methods (n = 57). By multivariate analysis, the only predictor of a higher ejection fraction calculated by the biplane method was an anterior wall motion abnormality. This finding was tested prospectively in a separate group of 60 patients (group 2). Left ventriculograms in group 2 patients were stratified before analysis by the presence or absence of an anterior wall motion abnormality. In patients with anterior wall motion abnormalities, the biplane ejection fraction was greater than the single-plane value by 0.05 +/- 0.04 (range -0.03 to +0.15). In contrast, this difference in patients without anterior wall motion abnormalities was -0.01 +/- 0.04 (range -0.09 to +0.06; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of thallium-201 single-photon emission computed tomography after intravenous dipyridamole using different quantitative measures of coronary stenosis severity and receiver operator characteristic curves

The presence of significant coronary artery disease in individual vessels was assessed using thallium-201 single-photon emission computed tomography (SPECT) after intravenous dipyridamole. Coronary angiograms were analyzed using quantitative computer-assisted techniques in 81 men patients. Eleven men with a less than 3% probability of coronary artery disease were used as a control population. Three definitions of a hemodynamically significant coronary stenosis were studied independently: (1) a greater than 50% luminal diameter narrowing; (2) an absolute cross-sectional area less than or equal to 2.0 mm2; or (3) a greater than or equal to 70% cross-sectional area obstruction. Myocardial perfusion after dipyridamole was analyzed using the quantitative (polar map) method in 213 regions from the group with known coronary anatomy and using 33 regions from the group with a low likelihood of disease. Receiver operating characteristic curves were used to define the best cut-off point for the discrimination between normal and abnormal perfusion. When related to each of the three quantitative angiographic criteria, the optimum balance between sensitivity and specificity occurred at a defect size of greater than or equal to 8% for the left anterior descending artery, greater than or equal to 4% for the circumflex artery, and greater than 0% for the right coronary artery. Using a luminal diameter narrowing of greater than 50% to define the presence of significant coronary artery disease, these corresponded to respective sensitivities and specificities of 0.82 and 0.76 for the left anterior descending artery, 0.71 and 0.71 for the circumflex artery, and 0.76 and 0.82 for the right coronary artery. Thus analysis of receiver operator characteristic curves provides a means to define abnormalities for the SPECT polar map program after dipyridamole stress. Different definitions of coronary stenosis significance as determined by quantitative angiography did not substantially alter the results of the thallium imaging data and thus suggest that these definitions are functionally similar.

Implications of inferior ST-segment elevation accompanying anterior wall acute myocardial infarction for the angiographic morphology of the left anterior descending coronary artery morphology and site of occlusion

Inferior ST-segment elevation during anterior wall acute myocardial infarction (AMI) due to left anterior descending (LAD) coronary artery occlusion is unusual and was not previously investigated. This study tested the hypothesis that inferior ST-segment elevation during anterior AMI predicts a specific angiographic morphology that satisfies 2 necessary conditions: (1) mass of ischemic anterior wall myocardium is relatively small, resulting in a weaker anterior injury current and less reciprocal inferior ST-segment depression; and (2) there is concomitant inferior wall transmural ischemia that further shifts the inferior ST segments upward. The study group consisted of 42 consecutive patients with anterior AMI undergoing angiography at 4.1 days (range 0 to 14). Coronary angiograms were examined for 3 features: (1) site of LAD artery occlusion (a distal obstruction implying a smaller mass of ischemic anterior wall myocardium), (2) LAD artery extension onto inferior wall of left ventricle (termed a "wrap around" vessel), and (3) collateral flow from LAD artery to inferior wall. The latter 2 features would be expected to contribute to inferior wall transmural ischemia. Acute inferior ST-segment elevation (sum of ST-segment deviation in leads II, III and aVF greater than or equal to 3.0 mm) was seen in 7 patients (16%). A greater number of LAD artery branches proximal to the site of occlusion was significantly correlated with less inferior ST-segment depression (r = 0.59, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Reduction in injection pain using buffered lidocaine as a local anesthetic before cardiac catheterization

Previous reports have suggested that pain associated with the injection of lidocaine is related to the acidic pH of the solution. To determine if the addition of a buffering solution to adjust the pH of lidocaine into the physiologic range would reduce pain during injection, we performed a blinded randomized study in patients undergoing cardiac catheterization. Twenty patients were asked to quantify the severity of pain after receiving standard lidocaine in one femoral area and buffered lidocaine in the opposite femoral area. The mean pain score for buffered lidocaine was significantly lower than the mean score for standard lidocaine (2.7 +/- 1.9 vs. 3.8 +/- 2.2, P = 0.03). The pH adjustment of standard lidocaine can be accomplished easily in the catheterization laboratory before injection and results in a reduction of the pain occurring during the infiltration of tissues.

Comparison of coronary angiographic features and oral dipyridamole thallium 201 tomography

Coronary angiography and left ventriculography is commonly used to identify those patients with incomplete infarctions and therefore, a need for revascularization. The authors compared coronary angiography and left ventriculography with thallium 201 tomography using oral dipyridamole to identify patients with potential ischemia in the infarct zone indicating viable tissue. Forty-five patients (37 men, 8 women) with acute myocardial infarctions (29 anterior, 16 inferior) who received intravenous thrombolytic therapy were studied. On the basis of the left ventriculograms, only 16 patients were judged to have residual function in the infarct zone. Six of these patients had no thallium redistribution in the infarct zone, indicating lack of residual ischemia. Of the 29 patients with no residual function in the infarct zone, 18 had redistribution in the infarct zone, suggesting residual ischemic myocardium and thus viable tissue. Among the 32 patients with open infarct vessels, 15 had no redistribution in the infarct zone, but of the remaining 13 patients with occluded infarct vessels, 9 had redistribution in the infarct zone indicating residual ischemia and thus viable tissue. The authors' data suggest that neither wall motion analysis by left ventriculography nor the angiographic status of the infarct vessel identifies those patients with residual ischemia as evidenced by thallium tomography using oral dipyridamole.

Direct coronary vasodilation induced by intracoronary vasoactive intestinal peptide

Vasoactive intestinal peptide (VIP) is a neurotransmitter that has been identified in epicardial coronary arteries. To evaluate the direct effect of VIP on coronary hemodynamics and blood flow, graded doses of VIP (0.01, 0.03, 0.10, and 0.30 micrograms/min) were infused into the left coronary artery of 7 patients at the time of diagnostic cardiac catheterization for chest pain syndromes. None of the patients had coronary stenoses greater than 50% during subsequent angiography. Coronary sinus VIP concentrations increased during each infusion (22 +/- 28 pg/ml at baseline to 109 +/- 22 pg/ml at 0.30 micrograms/min; p less than 0.05), but arterial VIP was elevated (39 +/- 29 pg/ml) only at the maximal dose of 0.30 micrograms/min. During all dosages of VIP, heart rate, right atrial and left ventricular end-diastolic pressure, and the heart rate x blood pressure product did not change. Moreover, neither mean aortic pressure nor left ventricular peak + dP/dt changed significantly at doses less than 0.30 micrograms/min; at 0.30 micrograms/min, mean aortic pressure decreased (97 +/- 15 to 90 +/- 15 mm Hg; p less than 0.05) and LV peak + dP/dt increased (1,621 +/- 230 to 1,801 +/- 226 mm Hg/s; p less than 0.05). Compared to baseline, the arterial-coronary sinus O2 content difference and myocardial O2 extraction diminished progressively at the 0.03, 0.10, and 0.30 micrograms/min doses of VIP (118 +/- 12 ml O2/L vs. 94 +/- 15, 70 +/- 9, and 61 +/- 26 ml O2/L, respectively, and 0.64 +/- 0.05 vs. 0.53 +/- 0.10, 0.38 +/- 0.06, and 0.34 +/- 0.15, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Reduction in radiation exposure during coronary angiography

In addition to lead shielding, increased distance between the operator and x-ray source will lower radiation exposure. To utilize this principle, we interposed a 24 in. piece of pressure tubing between the catheter used for coronary angiography and the manifold apparatus. Radiation exposure to the hand of the operator during coronary angiography was compared with and without the extension tubing. When corrected for the differences in exposure time, operator exposure was 5.38 mrem/min without the extension and 4.84 mrem/min with the extension. Although this is a small difference in exposure/min, a substantial reduction in exposure could accumulate over a 1 yr period. Insertion of this extension tube into the catheter system is a simple and safe way to further reduce operator exposure during coronary angiography.

Reverse redistribution of thallium-201 detected by SPECT imaging after dipyridamole in angina pectoris

Reverse redistribution refers to a thallium-201 perfusion defect that develops or becomes more evident on delayed imaging compared with the initial image immediately after stress. To determine the diagnostic importance of reverse redistribution after intravenous dipyridamole, thallium-201 single photon emission computed tomography and quantitative coronary arteriography were performed in 90 men with angina pectoris. Of the 250 myocardial segments analyzed, reverse redistribution was present in 17 (7%). Minimal coronary cross-sectional area in proximal vessel segments was less than or equal to 2.0 mm2 more often in regions with transient perfusion abnormalities than in regions with reverse redistribution (66 vs 29%, p less than 0.05). Compared with regions exhibiting transient perfusion abnormalities, regions with reverse redistribution had larger proximal arterial diameters (1.9 +/- 1.1 vs 1.3 +/- 1.1 mm, p less than 0.001) and cross-sectional areas (3.9 +/- 3.1 vs 2.2 +/- 2.6 mm2, p less than 0.001). Coronary artery dimensions and relative stenosis severity did not differ between those regions with normal perfusion and those with reverse redistribution. Reverse redistribution detected by thallium-201 single photon emission computed tomographic imaging after dipyridamole is uncommon, appears to occur as frequently in normal subjects as in patients undergoing coronary arteriography and does not indicate the presence of severe coronary artery disease.

Reversible segmental left ventricular dysfunction after coronary angioplasty

Patients with chronic segmental myocardial dysfunction may demonstrate improvement after coronary revascularization. To evaluate the early effects of percutaneous transluminal coronary angioplasty (PTCA) on resting left ventricular segmental function, we obtained serial two-dimensional echocardiograms 1.1 +/- 0.9 days before and 3.1 +/- 2 days after elective PTCA in 40 patients. Echocardiograms were reviewed in a blind fashion; left ventricular segmental wall motion was analyzed in four short-axis views, and a score was assigned to each region (0, normal; 1, hypokinetic; and 2, akinetic). Abnormal regional wall motion was present in 20 of the patients before PTCA. Summed segment scores in these 20 patients showed an improvement in regional wall motion from 4.5 +/- 2.5 to 1.6 +/- 2.1 (p less than 0.01) after successful PTCA. Similar results were obtained when the patients were divided into those with or without a previous myocardial infarction. Improvement occurred in the seven patients without a previous myocardial infarction; the summed segment score decreased from 4.2 +/- 3.4 to 0.86 +/- 1.6 (p less than 0.05) after PTCA. Ten of the 13 patients with a prior myocardial infarction demonstrated improvement in wall motion after PTCA; the summed segment scores decreased 54% (p less than 0.001). Of the 260 segments analyzed in the study, 180 were normal before and after PTCA. Forty-nine of the 69 hypokinetic segments were normal, and 10 of 12 akinetic segments were hypokinetic after successful coronary revascularization. There was no deterioration in wall motion after PTCA.(ABSTRACT TRUNCATED AT 250 WORDS)

Variability of coronary flow reserve obtained immediately after coronary angioplasty

Coronary flow reserve (CFR) improves in most patients immediately following coronary angioplasty (PTCA). The degree of improvement, however, may be variable and its predictive value for a favorable long-term angiographic result is unknown. To evaluate these issues, we used digital subtraction angiography to measure CFR in 15 patients before and immediately after PTCA. Minimum coronary diameter improved and percent diameter stenosis was reduced immediately following PTCA (from 0.75 +/- 0.35 mm to 2.19 +/- 0.56 mm, and from 74 +/- 12% to 27 +/- 15%, respectively; p less than 0.001). While CFR improved in patients immediately following PTCA (from 1.49 +/- 0.75 to 2.68 +/- 1.73; p less than 0.05), a substantial variability in CFR measurements (range 0.80 to 8.33) was present. At repeat arteriography 2.9 +/- 0.6 months later, 4 patients demonstrated restenosis. Compared with the 11 patients without restenosis, those with restenosis had similar coronary dimensions and CFRs immediately following PTCA. We conclude that coronary flow reserve, determined by digital subtraction angiography, improves in most patients immediately after PTCA but the degree of improvement is variable. Its ability to predict long-term angiographic outcome remains uncertain.

Coronary artery fistula: an abnormality affecting all age groups

A coronary artery fistula is an abnormal communication between a coronary artery and a cardiac chamber, great vessel, or other vascular structure. It is an infrequent but potentially important abnormality that can affect any age group. Most are congenital in origin, although other etiologies, in particular trauma, have been identified. Many are small and found incidentally during coronary arteriography, while others are identified as the cause of a continuous murmur, myocardial ischemia, congestive heart failure, or, rarely, bacterial endocarditis. The diagnosis should be considered in any patient presenting with a continuous murmur or in the setting of congestive heart failure, myocardial ischemia, or bacterial endocarditis without an obvious etiology. The pathophysiologic mechanisms resulting in symptoms include cardiac volume overload due to the shunting of blood and reduction of the myocardial blood supply due to "coronary steal." The diagnosis of coronary artery fistula may be suggested by the finding of a continuous murmur in a precordial location, which is atypical for patent ductus arteriosus. Two-dimensional echocardiography may demonstrate dilated coronary arteries, and pulse-wave and color-flow Doppler examinations can display turbulent flow in the suspected fistula and its receiving chamber or vessel. Angiography is generally needed to confirm the diagnosis and elucidate anatomic detail. The natural history of coronary artery fistula is variable, with long periods of stability in some patients and gradual progression of symptoms in others. Small fistulas detected incidentally at the time of angiography do not require immediate surgical correction, but careful follow-up is indicated because the potential for enlargement with physiologically important shunting exists and cannot readily be predicted. Spontaneous closure is uncommon. Surgical repair of the fistula is recommended for symptomatic patients and for some without symptoms because a quantitatively small shunt does not predict freedom from future symptoms or complications. Those selected for medical management must be followed closely.

Effects of intravenous isradipine on left ventricular performance during rapid atrial pacing in coronary artery disease

The effects of isradipine, a new dihydropyridine calcium antagonist, were evaluated in 24 patients referred for elective cardiac catheterization because of suspected coronary artery disease. Hemodynamics and left ventricular (LV) function (by digital subtraction angiography) were measured at baseline and during rapid atrial pacing (mean peak heart rate 135 beats/min), which induced chest pain or electrocardiographic changes in all patients. After a control pacing period, intravenous isradipine (0.01 mg/kg, n = 16) or placebo (n = 8) was administered in a double-blind fashion and all variables were measured again at baseline and during pacing to the same maximum heart rate. Before isradipine was given, pacing had no effect on systolic blood pressure, while increasing diastolic blood pressure (68 +/- 8 to 87 +/- 11 mm Hg, p less than 0.0001) and LV end-diastolic pressure measured in the immediate postpacing period (13 +/- 5 to 18 +/- 6 mm Hg, p less than 0.03) and decreasing LV end-diastolic volume index (59 +/- 18 to 40 +/- 12 ml/m2, p less than 0.001), stroke volume index (37 +/- 11 to 23 +/- 10 ml/m2, p less than 0.0001), ejection fraction (0.64 +/- 0.07 to 0.53 +/- 0.12, p less than 0.0003) and percent regional shortening in 4 of 5 myocardial wall segments. During pacing after isradipine, systolic and diastolic blood pressures were lower, ejection fraction was higher and percent regional shortening decreased in only 2 of 5 myocardial segments. In comparison to placebo, isradipine increased baseline heart rate, ejection fraction and stroke volume index while it decreased arterial pressure and end-systolic volume index before the second pacing period.(ABSTRACT TRUNCATED AT 250 WORDS)

Management of patients after coronary angioplasty

Coronary angioplasty is an accepted method of revascularization in selected patients with coronary artery disease. Immediately after a successful angioplasty, initial management concentrates on the detection and treatment of coronary artery spasm and acute vessel closure, should these complications occur. Once the patient is ambulatory, a formal assessment of the success of the procedure may be appropriate in some patients. Medical management is aimed at reducing the risk of coronary spasm and modifying those factors that may cause restenosis. During the next six months, coronary risk factor modification should be started while the patient is observed for symptoms that may suggest restenosis.

Coronary hemodynamic effects of intravenous vasoactive intestinal peptide in humans

Vasoactive intestinal polypeptide (VIP), a probable neurotransmitter, is present in the hearts of experimental animals and is a coronary vasodilator in dogs. We evaluated the coronary hemodynamic effects of intravenously infused VIP in 11 men at two rates that modestly raised circulating VIP concentrations. The decreases in coronary and systemic vascular resistances during the second infusion, 33 and 31%, respectively, were slightly but insignificantly greater than the 24% decrease in pulmonary vascular resistance. Coronary sinus levels of 6-keto-prostaglandin F1 alpha were not elevated during the infusions, and cyclooxygenase inhibition did not significantly blunt coronary vasodilation. However, myocardial oxygen uptake rose significantly during both infusions. To test for a direct coronary vasodilator effect, we infused VIP into the left coronary artery of four other men at four levels. The maximum decline in coronary vascular resistance was 46% and was not associated with an increase in myocardial oxygen uptake. We conclude that 1) intravenous administration of low to intermediate doses of VIP in humans is associated with substantial coronary vasodilation, 2) the coronary bed appears to be at least as responsive as other vascular beds, 3) the coronary vasodilation is due to both direct and indirect effects, and 4) the coronary vasodilation does not appear to be mediated by prostaglandins.

Limitations of the metabolic rate meter for measuring oxygen consumption and cardiac output

Over the past few years, a metabolic rate meter has been introduced for easy measurement of oxygen consumption. However, its accuracy is unproved. In 40 patients (26 men, 14 women, ages 34 to 73 years), cardiac output was measured simultaneously by thermodilution and the Fick method using the metabolic rate meter to quantitate oxygen consumption. In comparison with thermodilution, the results using the Fick method were low (5.26 +/- 1.18 vs 4.14 +/- 0.99 liters/min, respectively, p less than 0.01). In 18 patients cardiac output also was measured by the Fick method using a Douglas bag to quantitate oxygen consumption. In these patients, oxygen consumption measured with the metabolic rate meter was lower than that obtained using the Douglas bag (168 +/- 25 vs 216 +/- 42 ml/min, respectively, p less than 0.01). With the Douglas bag, the Fick and thermodilution cardiac output measurements were similar (4.68 +/- 1.08 vs 4.87 +/- 0.86 liters/min, respectively, difference not significant), and they differed by less than or equal to 10% in 15 patients. In contrast, with the metabolic rate meter, the results of thermodilution were higher than those with the Fick method (4.84 +/- 0.95 vs 3.60 +/- 0.71 liters/min, respectively, p less than 0.01), and differed by less than or equal to 10% in only 1 patient (p less than 0.01). Thus, the values for oxygen consumption and cardiac output obtained with the metabolic rate meter are lower than actual values. This device is less accurate than the Douglas bag.

In vivo assessment of a digital angiographic method to measure absolute coronary artery diameters

Several techniques exist for the quantification of absolute coronary artery diameters using radiologic methods. An in vivo assessment of a quantitative technique based on direct digitally acquired images was performed by imaging inflated angioplasty balloons (n = 25), balloon catheter shafts (n = 16) and coronary guidewires (n = 20) at the time of coronary angioplasty. After this, the actual size of the objects was determined with a micrometer. Diameters measured by the quantitative digital method had an excellent correlation with the actual diameters (digital diameter = 0.80 [actual diameter] + 0.32; n = 61; r = 0.97; standard error of the estimate = 0.26 mm; p less than 0.001). Moreover, the correlation between interobserver and intraobserver measurements was excellent (r = 0.99 for both, standard error of the estimate = 0.16 mm and 0.09 mm, respectively). However, there was a consistent error present that was related to the size of the object measured. Objects less than 0.5 mm were consistently overestimated and objects greater than 1 mm were usually underestimated by the digital technique, although the actual magnitude of the error was small. Objects less than 0.5 mm in diameter were overestimated by 0.41 +/- 0.11 mm and objects greater than 1 mm were underestimated by 0.23 +/- 0.19 mm. Based on an analysis of the error present, correction algorithms were formulated and tested prospectively using an additional 29 object measurements. This resulted in an improvement in the quantification of the diameters with a smaller magnitude of error. This in vivo assessment suggests that the rapid online assessment of absolute coronary artery diameters is possible, but also demonstrates important errors inherent in this method.

Care of the patient after coronary angioplasty

Because coronary angioplasty is being increasingly used as a treatment for coronary artery disease, the proper evaluation and management of patients after the procedure are important issues. Although coronary angioplasty is a complex technical procedure, the methods routinely used to evaluate its results have many shortcomings. Although the initial results of the procedure are assessed most commonly by the visual interpretation of video images and coronary angiograms, quantitative angiography, trans-stenotic pressure gradients, and coronary flow reserve measurements have also been used. In the period after coronary angioplasty, success can be evaluated by patients' clinical improvement in symptoms and their stress responses to various functional tests. The management of the patient during the first 24 hours after angioplasty should focus on the prevention, detection, and, if necessary, treatment of acute vessel closure. During the subsequent 6 months, the emphasis should shift to the evaluation of recurrent symptoms and prevention of restenosis. We discuss the methods used to assess the results of coronary angioplasty and suggest guidelines for managing patients after the procedure.

Transcardiac serotonin concentration is increased in selected patients with limiting angina and complex coronary lesion morphology

Serotonin is released by activated platelets and may act as a mediator to initiate or sustain certain unstable syndromes of ischemic heart disease in humans. To determine whether or not serotonin concentration increases across the coronary bed in patients with severe, limiting angina, we measured central aortic and coronary sinus serotonin concentrations by a sensitive radioenzymatic assay in 39 patients with coronary artery disease and 13 patients with minimal or no coronary artery lesions as detected by arteriography. Although no difference existed in the mean aortic or coronary sinus serotonin concentrations between these two groups, elevated coronary sinus serotonin concentrations were detected in 23% of those with coronary artery disease. The coronary sinus and aortic serotonin concentration difference was greater in patients with significant coronary artery disease (0.6 +/- 6.62 ng/ml) compared with patients without significant coronary artery disease (-5.6 +/- 10.32 ng/ml) (mean +/- SD) (p less than 0.05). Further analysis revealed that patients with eccentric, irregular coronary artery lesions or intraluminal filling defects had a significantly elevated coronary sinus and aortic serotonin difference (3.1 +/- 5.54 ng/ml) compared with those with smooth concentric lesions (-1.9 +/- 6.61 ng/ml) (p less than 0.02). These data suggest that serotonin is released into the coronary circulation of some patients with coronary artery disease, especially those with frequent angina and complex coronary lesions. Although serotonin may be released in some patients with coronary artery disease, the specific pathophysiologic role of serotonin in the development or perpetuation of certain coronary syndromes in humans remains to be determined.