Adenosine thallium-201 is superior to exercise thallium-201 for detecting coronary artery disease in patients with left bundle branch block.

OBJECTIVES: We sought to assess the comparative diagnostic accuracy of adenosine versus exercise in conjunction with thallium-201 scintigraphy for the detection and localization of coronary artery disease in patients with left bundle branch block on the rest electrocardiogram (ECG). BACKGROUND: Patients with left bundle branch block on the rest ECG frequently have artifactual reversible septal perfusion defects on exercise thallium-201 scintigraphy. Adenosine thallium scintigraphy is a theoretically attractive alternative in these patients. METHODS: One hundred seventy-three consecutive patients with left bundle branch block were evaluated with either exercise thallium (n = 56) or adenosine thallium (n = 117) scintigraphy. The tomographic thallium images were interpreted visually with adjunctive quantitative analysis. Follow-up cardiac catheterization was performed in 31 of the 56 patients in the exercise thallium group and 42 of the 117 patients in the adenosine thallium group. RESULTS: Minor subjective side effects were noted in most patients in the adenosine thallium group (86%); atrioventricular block occurred in seven patients (6%). The overall predictive accuracy was 93% in the adenosine thallium group and 68% in the exercise thallium group (p = 0.01). The combined specificity for the detection of disease in the coronary arteries subtending the septum (the left anterior descending and right coronary arteries) was only 42% with exercise thallium scintigraphy versus 82% with adenosine thallium scintigraphy (p < 0.0002). CONCLUSIONS: Adenosine thallium imaging 1) was superior to exercise thallium imaging in the detection of coronary artery disease in patients with left bundle branch block; 2) obviated septal artifacts, thereby markedly improving the specificity in the left anterior descending and right coronary arteries; and 3) was safe in patients with left bundle branch block.

Esmolol: a new ultrashort-acting beta-adrenergic blocking agent for rapid control of heart rate in postoperative supraventricular tachyarrhythmias.

Prompt control of heart rate is important for successful treatment of supraventricular tachyarrhythmias early after open heart surgery when sympathetic tone is high and ventricular response rates may be rapid. Esmolol, a new ultrashort-acting (9 minute half-life) beta-receptor blocking agent, was given by continuous intravenous infusion for up to 24 hours in 24 patients (21 with isolated coronary bypass surgery and 3 with valve replacement) 1 to 7 days after surgery. Atrial fibrillation was present in 9 patients, atrial flutter in 2 and sinus tachycardia in 13. Eleven patients had received intravenous digoxin (average dose 0.6 mg, average serum level 1.19 mg/100 ml) before esmolol infusion without adequate control of the supraventricular tachyarrhythmia. After a 1 minute loading infusion of esmolol (500 micrograms/kg per min), maintenance dose, titrated to heart rate and blood pressure response, varied from 25 to 300 micrograms/kg per min. After esmolol administration, at an average dose of 139 +/- 83 micrograms/kg per min, mean heart rate decreased from 130 +/- 15 to 99 +/- 15 beats/min. Within 5 to 18 minutes after initiation of therapy, all patients had achieved a 15% reduction in heart rate at a maintenance dose of 150 micrograms/kg per min or less. A 20% reduction in heart rate was attained in 19 of the 24 patients, and conversion to sinus rhythm occurred during esmolol infusion in 5 of the 11 patients with atrial flutter or fibrillation. Transient asymptomatic hypotension (less than 90/50 mm Hg) was seen in 13 patients, requiring cessation of esmolol therapy in 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Comprehensive noninvasive evaluation of left atrial myxomas using cardiac cine-computed tomography.

This report describes the first clinical experience with ultrafast (cine) computed tomography for evaluating intracardiac masses. Two patients had a left atrial myxoma that was comprehensively described (size, location, site of attachment and relation to the mitral valve) preoperatively by cine-computed tomography. The information content of the studies exceeded that of two-dimensional echocardiography, and both patients were operated on without invasive cardiac catheterization. This early experience with a new minimally invasive high temporal and spatial resolution technology suggests that cine-computed tomography may be uniquely suited for precise evaluation of intraatrial masses.

Mitral valve replacement early after myocardial infarction: attendant high risk of left ventricular rupture.

Between 1969 and 1983, 608 patients underwent mitral valve replacement surgery at Cedars-Sinai Medical Center. Perioperative rupture of the left ventricular myocardium complicated seven operations (1.2%), five of them in the 247 patients with concomitant ischemic heart disease. Six ruptures were fatal. Relative incidences of seven previously hypothesized predisposing factors were determined for patients with and without myocardial rupture. In addition, because of the apparent frequency of association with ischemic heart disease and because all ruptures were posterior or posterolateral, patients were also categorized by prior history of posterior myocardial infarction: 177 patients had none, whereas 49 patients had a remote and 21 patients a recent (less than or equal to 1 month) posterior wall infarct. Four ruptures (accounting for 57% of all ruptures) occurred in the 21 patients (19% incidence) with a recent posterior infarct, compared with only three ruptures in the 587 patients (0.5%) without a recent posterior wall infarct (p = 0.000). None of the factors of age, sex, valve pathology, etiology of valve lesion, concomitant coronary disease, valve substitute or intraoperative myocardial preservation were associated with perioperative rupture. These data establish a low overall incidence of ventricular rupture after mitral valve replacement, high fatality and possible etiologic association with recent posterior wall infarction.

Fascicular conduction disturbances and ischemic heart disease: adverse prognosis despite coronary revascularization.

In patients with ischemic heart disease, fascicular conduction disturbances are associated with increased mortality. This study reveals that increased mortality also exists for certain types of fascicular conduction disturbances after myocardial revascularization. In 227 consecutive patients undergoing bypass surgery, 24 had preoperative and an additional 52 developed at surgery a fascicular conduction disturbance. At 66 +/- 14 months of follow-up, 6 (4%) of 148 control patients without pre- or postoperative fascicular conduction disturbances had died from cardiac causes. Although right bundle branch block and left hemifascicular block were the most common form of fascicular conduction disturbance, only 1 of 55 of these patients died (p = NS). Mortality rates were much higher for patients with left bundle branch block or an intraventricular conduction defect; 8 (38%) of 21 died from cardiac causes (p less than 0.05). A high risk subgroup was identified by comparing 14 consecutive patients with left bundle branch block or an intraventricular conduction defect who survived more than 1 year postoperatively with 21 consecutive patients with these same conduction defects who died within 1 year of surgery. The following variables were significantly (p less than 0.05) different (survivors versus nonsurvivors): age (58 +/- 7 versus 65 +/- 9 years); class IV angina (2 of 14 versus 16 of 21), prior myocardial infarction (9 of 14 versus 21 of 21), left ventricular ejection fraction (53 +/- 18 versus 41 +/- 15%), three vessel disease (9 of 14 versus 20 of 21) and left ventricular aneurysm (2 of 14 versus 13 of 21).(ABSTRACT TRUNCATED AT 250 WORDS)

Fibrinolytic therapy of St. Jude valve thrombosis under guidance of digital cinefluoroscopy.

Fibrinolytic therapy is an alternative to urgent reoperation for patients with St. Jude prosthetic valve thrombosis, but requires an accurate method for repeated assessment of prosthetic function. Since the St. Jude valve is not well visualized by conventional cinefluoroscopy, digital subtraction techniques were developed that improved visualization of the value and allowed assessment of leaflet separation and velocity. A 74 year old woman with prosthetic valve thrombosis 5 years after St. Jude aortic valve placement had an opening angle of 58 degrees (normal range 10 to 13; n = 8) with a maximal opening velocity of 1.37 degrees/ms (normal range 2.46 to 2.93). The closing angle was 125 degrees (normal range 120 to 127) with a maximal closing velocity of 1.38 degrees/ms (normal range 2.24 to 3.60). The patient received 250,000 U of streptokinase intravenously, then 100,000 U/h for 72 hours. Improvement in auscultatory findings occurred at 12 hours; repeat digital cinefluoroscopy showed an opening angle of 20 degrees with a maximal velocity of 2.77 degrees/ms, and a closing angle of 126 degrees with a maximal velocity of 1.91 degrees/ms. Digital cinefluoroscopy 4 weeks after discharge on warfarin and dipyridamole therapy was unchanged. There have been no thromboembolic complications after 6 months of follow-up. Thus, digital cinefluoroscopy is a new noninvasive technique that permits accurate measurement of normal and abnormal St. Jude leaflet function. Intravenous streptokinase dissolution of prosthetic valve thrombosis under digital cinefluoroscopic guidance may be an acceptable alternative to emergency reoperation. The frequency and significance of residual subclinical leaflet dysfunction after fibrinolytic therapy and the indications for elective reoperation require further evaluation.

Hemodynamic differentiation of pathologic and physiologic stenosis in mitral porcine bioprostheses.

Porcine bioprostheses are physiologically stenotic valves. Degenerative calcification leading to pathologic stenosis is an increasingly recognized serious late complication of mitral valve replacement with a porcine bioprosthesis. Hemodynamic differentiation of pathologic from physiologic stenosis is important for identification of porcine bioprosthetic valve dysfunction. In 42 patients with a normal Hancock porcine bioprosthesis (standard model, sizes 27 to 33 mm), mean diastolic flow (65 to 461 ml/s), mean gradient (2.0 to 13.4 mm Hg) and effective orifice area (1.1 to 4.4 cm2) were determined at rest, during epicardial pacing (90, 110 and 130/min) and with isoproterenol infusion. A statistically significant increase in mean gradient occurred with increases in flow and decreases in valve size (p less than 0.05). Effective orifice area increased significantly as flow rate increased and as valve size increased (p less than 0.05). These measurements were compared with those in 16 patients with pathologically confirmed porcine bioprosthetic valve stenosis: 8 patients with reoperation (1.1% per patient-year) 3 to 8.5 years after mitral valve replacement and 8 previously reported abnormal cases. Stenotic failure rate was inversely related to valve size (2.1, 1.4, 0.5 and 0% per patient-year for sizes 27 to 33 mm). Stenotic and normal bioprostheses were not accurately differentiated on the basis of a single value for gradient or effective orifice area. A mathematical model that related flow to the square root of the mean gradient allowed complete separation of stenotic from normal prosthetic valve function, after valve size was accounted for and normal confidence limits were established (r = 0.74 to 0.94, sizes 27 to 33, p less than 0.0001). The effective orifice area-flow relation did not provide accurate differentiation of abnormal from normal function. Thus, normal mitral bioprostheses have significant transvalvular gradients whose magnitude depends on flow. Risk of stenotic failure is increased in the smaller valves, which have a larger gradient at implantation. Differentiation of pathologic from physiologic stenosis cannot be made on the basis of a single value for gradient or effective orifice area. Accurate hemodynamic differentiation is achieved by relating mean gradient to mean diastolic flow rate and valve size.

Treatment of severe platelet dysfunction and hemorrhage after cardiopulmonary bypass: reduction in blood product usage with desmopressin.

Impairment of platelet function commonly occurs after cardiopulmonary bypass, and may result in substantial bleeding. Because desmopressin acetate (a synthetic analogue of vasopressin) shortens bleeding time in a variety of platelet disorders, a controlled clinical trial of intravenous desmopressin was performed in 39 patients with excessive mediastinal bleeding (greater than 100 ml/h) and a prolonged template bleeding time (greater than 10 minutes) more than 2 hours after termination of cardiopulmonary bypass. Twenty-three desmopressin recipients and 16 control patients (no desmopressin) were similar in surgical procedure, pump time, platelet count, template bleeding time and amount of bleeding before therapy (p = NS). Compared with the control group, the patients receiving desmopressin (20 micrograms; mean 0.3 micrograms/kg) utilized fewer blood products (29 +/- 19 versus 15 +/- 13 units/patient; p less than 0.05), especially platelets (12 +/- 9 versus 4 +/- 7 units/patient; p = 0.004), while achieving a similarly effective reduction in mediastinal bleeding (4.8- and 4.3-fold, p = 0.001 for both). Severe platelet dysfunction was partially corrected within 1 hour after desmopressin infusion, during which interval no blood products were administered: the template bleeding time shortened (from 17 to 12.5 minutes, p less than 0.05), whereas the platelet count remained unchanged (at 96 +/- 35 and 105 +/- 31 X 10(3)/mm3, p = NS). The plasma levels of two factor VIII components increased: procoagulant activity (VIII:C) from 0.97 +/- 0.43 to 1.52 +/- 0.74 units/ml (p less than 0.05) and von Willebrand factor (VIII:vWF) from 1.28 to 1.78 units/ml (p less than 0.05); these increases correlated with the shortening of the bleeding time (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Ineffectiveness of colchicine for the prevention of restenosis after coronary angioplasty.

Colchicine, an antimitogenic agent, has shown promise in preventing restenosis after coronary angioplasty in experimental animal models. A prospective trial was conducted involving 197 patients randomized in a 2:1 fashion to treatment with oral colchicine, 0.6 mg twice daily (130 patients), or placebo (67 patients) for 6 months after elective coronary angioplasty. Treatment in all patients began between 12 h before angioplasty and 24 h after angioplasty. Compliance monitoring revealed that 96% of all prescribed pills were ingested. Demographic characteristics were similar in colchicine- and placebo-treated groups. A mean of 2.7 lesions/patient were dilated. Side effects resulted in a 6.9% dropout rate in the colchicine-treated patients. Complete quantitative angiographic follow-up was obtained in 145 patients (74%) with 393 dilated lesions. Quantitative angiographic measurements were obtained in two orthogonal views at baseline before angioplasty and immediately and at 6 months after angioplasty. The quantitative mean lumen diameter stenosis before angioplasty was 67% both in the 152 lesions in the placebo-treated group and in the 241 lesions in the colchicine-treated group; this value was reduced to 24% immediately after angioplasty in the lesions in both treatment groups. At the 6-month angiogram, lesions had restenosed to 47% lumen diameter narrowing in the placebo-treated group compared with 46% in the colchicine-treated group (p = NS). Forty-one percent of colchicine-treated patients developed restenosis in at least one lesion compared with 45% of the placebo-treated group (p = NS). In conclusion, colchicine was ineffective for preventing restenosis after coronary angioplasty.

Cine computed tomographic evaluation of aortocoronary bypass graft patency.

Evaluation of the patency of coronary bypass grafts has previously required hospitalization for invasive angiography. This report of three cases documents the unique capability of cardiac cine computed tomography to easily and accurately define coronary bypass graft patency. In each case, the findings altered therapeutic decisions. This early experience justifies wider application of this technique and suggests that it may eliminate the need for diagnostically motivated graft angiography. Large scale studies to establish the sensitivity and specificity of cardiac cine computed tomography for determining graft patency are indicated.

Sensitivity and specificity of assessing coronary bypass graft patency with ultrafast computed tomography: results of a multicenter study.

Because a significant number of all patients seen by cardiologists have had coronary bypass surgery, a relatively noninvasive method of assessing coronary bypass graft patency would be very helpful. Ultrafast computed tomography, by virtue of its rapid data acquisition time and reasonable spatial resolution, may be useful in this regard. To determine the sensitivity, specificity and predictive accuracy of this imaging modality as compared with cardiac catheterization, a multicenter study was undertaken. There were two parts to the study. Part I involved the evaluation of 179 grafts in 74 patients studied in the five participating centers between March 1985 and August 1986. Twenty-nine percent of these graft studies were found to be technically inadequate and were excluded before patency determinations began. The remaining group of 127 bypass grafts in 62 patients had studies adequate for interpretation. Fifty-one grafts were to the left anterior descending coronary artery or a diagonal branch, 37 to branches of the left circumflex artery and 28 to the right coronary artery or a posterior descending vessel; in addition, there were 11 internal mammary artery bypass grafts primarily into the left anterior descending or diagonal artery distribution. The sensitivity of detecting angiographically open grafts was 93.4%, the specificity of detecting angiographically closed grafts 88.9% and the predictive accuracy was 92.1%. A subsequent study (Part 2) was performed 9 months later to assess the ability to carry out technically adequate examinations. Of the 138 consecutive graft examinations (50 patients) included in this part of the study, 94.2% of the examinations were found to be technically adequate.(ABSTRACT TRUNCATED AT 250 WORDS)

Diffuse slow washout of myocardial thallium-201: a new scintigraphic indicator of extensive coronary artery disease.

When coronary artery disease is extensive and of relatively uniform severity, regional myocardial hypoperfusion may be balanced during stress, precluding development of spatially relative perfusion defects. Assessment of the washout of thallium-201 from myocardial regions may provide diagnostic assistance in these cases because washout analysis is spatially nonrelative and hypoperfused myocardial regions manifest a slow thallium-201 washout rate. In 1,265 consecutive patients having quantitatively analyzed stress-redistribution scintigraphy, 46 had a diffuse slow washout pattern with no or a maximum of one regional perfusion defect. Thirty-two underwent clinically indicated coronary angiography, and 23 (72%) of these were found to have three vessel or left main disease. Of 30 similar patients without a diffuse slow washout pattern and with no or a maximum of one perfusion defect, only 5 (17%) had extensive coronary disease. An independent relation between diffuse slow washout and extensive coronary disease was demonstrated by a Mantel- Haentzel chi-square analysis of a wide variety of other indexes of extensive disease. A diffuse washout abnormality, even in the absence of other scintigraphic, clinical or electrocardiographic indicators, carries a high predictive value for three vessel or left main coronary artery disease. The predictive value is maintained when the exercise level achieved is submaximal. Although an infrequent occurrence (3.6% of tested patients), a diffuse slow washout pattern without other scintigraphic indications of extensive coronary disease should lead to further diagnostic testing.

Extended acquisition for minimizing attenuation artifact in SPECT cardiac perfusion imaging.

Artifacts due to attenuation can complicate the interpretation of SPECT cardiac perfusion images, especially when the attenuated region corresponds to that of a coronary vascular distribution. Since methods of correction are limited, some patients undergo coronary angiography unnecessarily. Acquisition using a three-detector camera provides more data that can serve to minimize the effects of localized attenuation if incorporated into the final reconstruction set. In this article, a practical approach for interpreting SPECT cardiac perfusion images is outlined, demonstrating with an illustrative case how this approach can be clinically helpful.

Evidence-based risk assessment in noninvasive imaging.

UNLABELLED: Assessment of important clinical and economic outcomes has become central to the evaluation of patient care. Outcome research is deeply rooted in epidemiology, including the use of multivariable, risk-adjusted regression analysis. In our current health care environment, these methods are increasingly being used to assess the quality of care and to profile physicians and laboratories. Nuclear medicine physicians therefore need to better understand outcome methodologies in order to evaluate patient outcomes, develop guidelines, and decide on patient management. METHODS: This review describes the methods of assessing the diagnostic and prognostic value of nuclear medicine techniques and, briefly, the methodologic limitations of sample size, frequency and type of events, and follow-up periods and the incremental value of imaging. Also described are logistic regression and Cox proportional hazards modeling. Models for risk assessment are designed to identify whether patients require conservative (i.e., low-risk) or aggressive (i.e., high-risk) treatment. Treatment selection is currently based on risk assessment and the formation of an integrated, empiric risk stratification algorithm of care. This review also includes the methods of assessing economic effectiveness and quality-of-life issues for patients examined with nuclear medicine techniques. CONCLUSION: In this era of constrained resources, low-cost outpatient-based care may be of increasing importance. High-quality evidence of the clinical and economic outcome of nuclear imaging is essential for helping health care providers and payers assess its value.

Comparison of stress echocardiography and stress myocardial perfusion scintigraphy for diagnosing coronary artery disease and assessing its severity.

The cumulative published literature dealing with the most frequently utilized noninvasive cardiac stress imaging modalities (radionuclide myocardial perfusion scintigraphy and echocardiography) was reviewed to gain insight on their comparative diagnostic accuracies. To be included, studies had to be performed in conjunction with exercise or a commonly used intravenous pharmacologic stress agent (dipyridamole, adenosine or dobutamine) and had to report temporally related coronary angiography findings. A total of > 75 studies were included, involving > 7,000 patients. Exercise single-photon emitted computed tomographic (SPECT) scintigraphy was more sensitive than exercise echocardiography for detecting coronary artery disease (CAD), localizing it to the proper coronary artery distribution and correctly identifying the presence of multivessel CAD. Adenosine, dipyridamole, and dobutamine provided similar diagnostic accuracy when performed in conjunction with SPECT scintigraphy, and all were more accurate than dobutamine echocardiography. Clinical specificity was similarly high with adenosine SPECT, dipyridamole echocardiography, and exercise echocardiography, and lower with exercise SPECT. Normalcy rate was high for exercise SPECT and similar to clinical specificity for echocardiography.

Comparison of esmolol and nitroprusside for acute post-cardiac surgical hypertension.

Because acute systemic hypertension early after cardiac surgery has been linked to catecholamine elevation, an open-label, randomized, crossover study was performed to compare the efficacy of esmolol, a new ultra-short-acting intravenous beta-blocking agent, to nitroprusside, the standard therapy. Controlled drug infusions to maximal dosage (esmolol, 300 micrograms/kg/min, and nitroprusside, 10 micrograms/kg/min) were titrated to achieve at least a 15% reduction in systolic pressure. The blood pressure (BP) endpoint was achieved with esmolol (within 29 +/- 14 minutes) in 18 of 20 patients (90%), compared with 19 of 20 (95%) with nitroprusside infusion (within 21 +/- 15 minutes, difference not significant [NS]). Systolic BP decreased from 170 +/- 13 to 136 +/- 12 mm Hg (mean +/- standard deviation) with esmolol and from 170 +/- 13 to 141 +/- 13 mm Hg with nitroprusside infusion (both p less than 0.05). Diastolic BP was reduced from 71 +/- 12 to 64 +/- 11 mm Hg with esmolol and from 71 +/- 12 to 52 +/- 13 mm Hg with nitroprusside infusion (both p less than 0.05). Esmolol infusion resulted in decreased heart rate, cardiac index and stroke volume index and increased right atrial pressure (all p less than 0.05), whereas nitroprusside infusion resulted in increased heart rate and cardiac index and decreased right atrial pressure, pulmonary arterial wedge pressure and systemic vascular resistance (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Use of esmolol in hypertension after cardiac surgery.

Systolic hypertension, which is common soon after cardiac surgery, increases cardiac work and may threaten fresh vascular anastomoses. Because postoperative hypertension is often associated with elevated catecholamines and preoperative use of beta-blocking agents, esmolol, an ultrashort-acting beta-blocking agent, was compared with nitroprusside in a crossover study in this setting. Twelve patients, 18 to 28 hours after cardiac surgery (coronary artery bypass graft in 9, aortic valve replacement in 2 and valved aortic conduit with reimplantation of coronary arteries in 1 patient) received controlled infusions of esmolol (mean dosage 142 +/- 100 micrograms/kg/min, range 50 to 300 micrograms/kg/min) and nitroprusside (mean dose 1.6 +/- 1.3 micrograms/kg/min, range 0.5 to 2.75 micrograms/kg/min). In this open-label study, choice of the first drug was randomized, after which patients were then crossed over to the other study drug. Therapeutic response (greater than or equal to 15% systolic blood pressure reduction) was achieved in 11 of 12 esmolol patients and 12 of 12 nitroprusside patients. Both drugs significantly lowered systolic and diastolic blood pressure, as well as left ventricular stroke work index. While the cardiac index was decreased by esmolol and increased by nitroprusside, neither drug significantly changed stroke volume index. Systemic vascular resistance, unchanged by esmolol, was decreased significantly by nitroprusside. Oxygen saturation and Pao2, unchanged with esmolol, were both significantly reduced with nitroprusside. Thus, for hypertension early after cardiac surgery, esmolol is safe, effective and rapid and, compared with nitroprusside, results in less unwanted decrease in diastolic blood pressure and oxygen saturation, but there is more decrease in heart rate and cardiac index.

Noninvasive detection of active pericardial bleeding using cardiac blood pool scintigraphy.

The diagnosis of active pericardial bleeding has traditionally depended on an invasive documentation by needle aspiration, angiography, or direct inspection. Blood pool scintigraphy performed in 2 patients just before and after the development of hemopericardium revealed unique images in which acute pericardial bleeding manifested itself by an additional blood pool adjacent to the cardiac chambers. With appropriate attention to technical factors, such distinctive images should be highly specific for active bleeding into the pericardial sac.

Regional distribution of pulmonary blood volume: an index of pulmonary capillary wedge pressure determined from blood pool scintigraphy.

Progressive redistribution of pulmonary blood flow to the lung apices occurs with increasing degrees of left ventricular failure, and correlates with increasing pulmonary capillary wedge pressure (PCWP). If similar changes in pulmonary blood volume (PBV) occur, then technetium-99m equilibrium blood pool scintigraphy, by assessing relative distribution of PBV, may allow prediction of PCWP. Therefore 30 patients being monitored with pulmonary artery balloon flotation catheters underwent imaging. PCWP was compared with the average radioactive count density arising from apical (A) and basal (B) regions of interest within the right lung, expressed as an A/B ratio. Correlation was strong for patients imaged erect, either posteriorly (r = 0.864, p = 0.001) or in the 45 degrees left anterior oblique position (r = 0.842, p = 0.001), and only slightly less impressive for patients imaged supine (r = 0.678, p = 0.001). Especially when imaging was performed with patients erect, an A/B ratio greater than unity identified with high sensitivity (100%) and specificity (83 to 88%) an abnormally elevated PCWP (greater than 12 mm Hg). Moreover, directional changes in the A/B ratio reflected concomitant changes in PCWP after intervention. Thus, analysis of lung A/B radioactive count ratios obtained by equilibrium blood pool scintigraphy may be used to evaluate PCWP.

Poloxamer-188 as an adjunct to primary percutaneous transluminal coronary angioplasty for acute myocardial infarction.

Poloxamer-188 is a surfactant polymer with antithrombotic and hemorheologic properties that make it potentially useful as an adjunct to acute reperfusion strategies. Animal studies and early human studies have documented poloxamer-188 to be effective at improving myocardial salvage when used as an adjunct to intravenous thrombolytic therapy for acute myocardial infarction. The current trial was a prospective pilot study involving 150 patients who were randomized in a 2:1 fashion to a poloxamer-188 infusion for 48-hours versus placebo. The poloxamer-188 infusion was well tolerated subjectively. The only clinically significant laboratory abnormality noted was an elevation in the serum creatinine above 2.0 g/dl in 12% (n = 12) of the 98 poloxamer-188 treated patients versus 1 of the 52 (2%) of the placebo treated patients (p = 0.048). Clinical end points including reinfarction (1% vs 4%), cardiogenic shock (7% vs 6%), and death (9% vs 4%) were statistically similar in the poloxamer-188 and placebo groups, respectively (p = NS). Using quantitative nuclear techniques, final infarct size and myocardial salvage were statistically similar in the poloxamer-188 and placebo groups. Mean left ventricular ejection fractions 1 week post after infarction were 51% +/- 12% in the poloxamer-188 group and 52% +/- 13% in the placebo group (p = NS). Final infarct size, was not altered by the poloxamer- 188 infusion; however, it was significantly correlated with normal perfusion (Thrombolysis in Myocardial Infarction grade 3 flow) in the infarct vessel after angioplasty. This study documented poloxamer-188 to be ineffective as an adjunct to primary angioplasty for acute myocardial infarction and resulted in azotemia in 12% of the patients.