Non-Q-wave myocardial infarction following thrombolytic therapy: a comparison of outcomes in patients randomized to invasive or conservative post-infarct assessment strategies in the Veterans Affairs non-Q-wave Infarction Strategies In-Hospital (VANQWISH) Trial

OBJECTIVES

We wished to determine the effect of post-infarct management strategy on event rates (death or recurrent nonfatal myocardial infarction [MI]) in patients who evolved non-Q-wave MI (NQMI) following thrombolytic therapy.

BACKGROUND

Patients who evolve NQMI following thrombolytic therapy are often considered to be at high risk and are frequently managed with routine early invasive testing despite a lack of data supporting improved outcome.

METHODS

The Veterans Affairs Non-Q-Wave Infarction Strategies In-Hospital (VANQWISH) study included 115 patients who evolved NQMI following thrombolytic therapy. We compared the event rates in patients randomized to routine early coronary angiography with those in patients randomized to a conservative strategy of noninvasive functional assessment, with angiography reserved for patients with spontaneous or induced ischemia.

RESULTS

During an average follow-up of 23 months, 19 of 58 patients (33%) randomized to the invasive management strategy died or suffered recurrent nonfatal MI, compared with 11 of 57 patients (19%) randomized to the conservative strategy (p = 0.152). Equivalent numbers of patients were subjected to revascularization (percutaneous transluminal coronary angioplasty or coronary artery bypass graft). There were more deaths in the invasive management group than in the conservative management group (11 vs. 2). Excess deaths could not be attributed to periprocedural mortality.

CONCLUSIONS

Overall event rates (death or recurrent nonfatal MI) are comparable with conservative and invasive strategies in patients who evolve NQMI following thrombolytic therapy. Mortality rate in patients managed conservatively is low (3.5%), and routine invasive management may be associated with an increased risk of death.

Vascular remodeling and the local delivery of cytochalasin B after coronary angioplasty in humans

OBJECTIVES

This study sought to determine the safety, feasibility and outcome of local delivery of cytochalasin B at the site of coronary angioplasty.

BACKGROUND

Previous failures in the pharmacologic prevention of restenosis may have been related to inadequate dosing at the angioplasty site as a result of systemic drug administration. Alternatively, although previous experimental protocols have typically targeted control of excess tissue growth (intimal hyperplasia), it now appears that overall arterial constriction (vascular remodeling) is the major contributor to late lumen loss. Cytochalasin B inhibits the polymerization of actin and has proved to be a potent inhibitor of vascular remodeling in animal models.

METHODS

In this phase I, multicenter, randomized, controlled trial, cytochalasin B (or matching placebo) was administered to the site of a successful balloon angioplasty using a microporous local delivery infusion balloon.

RESULTS

The rate of drug delivery at a constant infusion pressure varied significantly from patient to patient (range 1.7 to 20.2 ml/min), perhaps related to a variable constricting effect of the atherosclerotic plaque on the infusion balloon. The minimal stenosis diameter after the procedure was slightly better in the active drug group (1.86 +/- 0.44 vs. 1.49 +/- 0.63 mm, p < 0.03), but this difference was not seen at four to six weeks. Although the study was not powered for clinical outcomes (n = 43), the combined end point (death, nonfatal infarction or repeat revascularization) was encountered in 20% of the patients receiving cytochalasin B and in 38% of the patients receiving placebo. Clinical restenosis occurred in 18% of the treatment group and 22% of the placebo group. There were no significant differences between groups in biochemical or electrocardiographic variables.

CONCLUSIONS

Cytochalasin B can be safely administered by local delivery after successful coronary angioplasty and warrants further study of its efficacy in reducing restenosis.

Randomized comparison of hemostasis techniques after invasive cardiovascular procedures

BACKGROUND

The arterial access required during most invasive vascular procedures provides a common source of complications and morbidity. This problem has been made worse by recent trends in earlier ambulation and more aggressive antihemostatic drug regimens. Despite these trends, no randomized trials have been reported comparing the 3 most commonly used techniques in achieving hemostasis at the arterial puncture site.

METHODS

A cohort of 400 patients undergoing catheterization laboratory procedures were randomly assigned to 1 of 3 groups of arterial compression: manual compression, mechanical clamp, and pneumatic compression device. Standard requirements of the trial included uniformity in initial compression times, patient instructions, nursing follow-up, and timing of ambulation as well as a structured interview and physical examination at 24 hours.

RESULTS

Prolonged compression was required in 13% of the manual group, 20% of the clamp group, and 35% of the pneumatic group (P <.0001). In-lab bleeding was more common in the pneumatic group (3%, 4%, and 16%, respectively, P <.0001), as was the need for an alternate compression technique (1%, 1%, and 27%, P <.0001). The groups also differed in respect to mean hematoma size (3.9 cm(2), 7.8 cm(2), and 19.8 cm(2), P =.036) and level of discomfort during compression (1.9, 2.2, and 3.1 on a 1- to 10-point scale, P <.0001). Comparable findings were observed in the subgroup of patients eligible for outpatient procedures.

CONCLUSIONS

Use of the pneumatic compression device leads to longer compression times, greater discomfort, more bleeding, and larger hematomas. Differences between manual compression and the mechanical clamp were more subtle but tend to favor use of the manual technique.

Improved accuracy and precision of thermodilution cardiac output measurement using a dual thermistor catheter system

OBJECTIVES

To assess whether thermodilution cardiac output determination based on measurement of injectate temperature in vivo leads to more accurate and precise estimates and to study the influence of chilled injectate on test performance.

BACKGROUND

Cardiac output measurement via right heart catheterization is used extensively for hemodynamic evaluation in a variety of diagnostic, perioperative and critical care settings. Maximizing accuracy is essential for optimal patient care.

METHODS

This prospective study of 960 thermodilution cardiac output measurements was conducted using conventional and dual thermistor techniques. Specialized dual thermistor right heart catheters were constructed using a second thermistor positioned to measure injectate temperature in vivo just prior to entry into the right atrium. To eliminate interinjection variability, a custom set-up was developed that permitted output measurement using both techniques simultaneously. Both ambient temperature injections and cooled injections were investigated.

RESULTS

The dual thermistor technique demonstrated significantly less measurement variability than the conventional technique for both ambient temperature (precision = 0.41 vs. 0.55 L/min, p < 0.001) and cooled (precision = 0.35 vs. 0.43 L/min, p = 0.01) injections. Similarly, the average range of cardiac output values obtained during five sequential injections in each patient was less using the dual thermistor approach (1.05 vs. 1.55 L/min, p < 0.001). The use of cooled injectate reduced the mean error of the dual thermistor technique but actually increased the mean error of the conventional technique. Even with ambient temperature injections, injectate warming during catheter transit varied considerably and unpredictably from injection to injection (2 SD range = -0.22 to 5.74 degrees C). Conventional ambient temperature and cooled measurements significantly overestimated Fick cardiac output measurements by 0.32 and 0.50 L/min, respectively (p < 0.001). In contrast, dual thermistor measurements were statistically similar (-0.08 and -0.08 L/min, p = 0.34) to Fick measurements.

CONCLUSIONS

This new dual thermistor approach results in a significant improvement in both precision and accuracy of thermodilution cardiac output measurement.

Systemic and translesional activation of coagulation, fibrinolytic, and inhibitory systems in candidates for coronary angioplasty: basal state and effect of successful dilation

OBJECTIVES

Thrombosis is a major contributor to complications associated with coronary interventions. It is unclear whether patients who have undergone angioplasty are predisposed to thrombus formation because of underlying perturbations in their hemostatic equilibrium.

METHODS

Concentration or activity was measured for 14 plasma proteins involved in the coagulation, fibrinolytic, and inhibitory systems. Baseline systemic measurements were compared between patients undergoing balloon angioplasty (n = 15) and normal subjects (n = 32), with sampling repeated at the end of the procedure. To better assess the local hemostatic environment near the site of dilation, intracoronary arterial samples were also obtained just proximal and distal to the dilated stenosis.

RESULTS

Multiple differences in measured coagulation proteins were found at baseline between the angioplasty candidates and control subjects, including higher mean concentration of plasma fibrinogen (P <.001) and lower high-molecular-weight kininogen concentration (P <.01) and factor XII activity (P <.01). Concentrations of the inhibitory proteins antithrombin III and protein S also differed significantly (P <.001 and P <.01, respectively), with a trend toward lower protein C concentration as well (P <.05). Finally, heightened fibrinolysis was suggested by a marked increase in mean plasma d-dimer concentration in the angioplasty candidates (293 +/- 191 ng/mL vs 116 +/- 31 ng/mL, P <.01), with a more modest increase in tissue plasminogen activator (P <.05) and decrease in alpha2-antiplasmin (P <.001). Importantly, none of the parameters obtained during the procedure differed significantly from samples obtained before and after angioplasty, and no translesional gradients were observed.

CONCLUSIONS

Patients with active ischemic syndromes who are considered candidates for coronary angioplasty demonstrate significant and multiple alterations in their coagulation, inhibitory, and fibrinolytic systems. However, no further changes were observed during coronary dilation, either systemically or locally, after pretreatment with typical doses of heparin and aspirin.

Chromatic distortion during angioscopy: assessment and correction by quantitative colorimetric angioscopic analysis

Angioscopy represents a diagnostic tool with the unique ability of assessing the true color of intravascular structures. Current angioscopic interpretation is entirely subjective, however, and the visual interpretation of color has been shown to be marginal at best. The quantitative colorimetric angioscopic analysis system permits the full characterization of angioscopic color using two parameters (C1 and C2), derived from a custom color coordinate system, that are independent of illuminating light intensity. Measurement variability was found to be low (coefficient of variation = 0.06-0.64%), and relatively stable colorimetric values were obtained even at the extremes of illumination power. Variability between different angioscopic catheters was good (maximum difference for C1, 0.022; for C2, 0.015). Catheter flexion did not significantly distort color transmission. Although the fiber optic illumination bundle was found to impart a slight yellow tint to objects in view (deltaC1 = 0.020, deltaC2 = 0.024, P < 0.0001) and the imaging bundle in isolation imparted a slight red tint (deltaC1 = 0.043, deltaC2 = -0.027, P < 0.0001), both of these artifacts could be corrected by proper white balancing. Finally, evaluation of regional chromatic characteristics revealed a radially symmetric and progressive blue shift in measured color when moving from the periphery to the center of an angioscopic image. An algorithm was developed that could automatically correct 93.0-94.3% of this error and provide accurate colorimetric measurements independent of spatial location within the angioscopic field. In summary, quantitative colorimetric angioscopic analysis provides objective and highly reproducible measurements of angioscopic color. This technique can correct for important chromatic distortions present in modern angioscopic systems. It can also help overcome current limitations in angioscopy research and clinical use imposed by the reliance on visual perception of color.

The electrocardiographic exercise test in a population with reduced workup bias: diagnostic performance, computerized interpretation, and multivariable prediction. Veterans Affairs Cooperative Study in Health Services #016 (QUEXTA) Study Group. Quantitative Exercise Testing and Angiography

BACKGROUND

Empirical scores, computerized ST-segment measurements, and equations have been proposed as tools for improving the diagnostic performance of the exercise test.

OBJECTIVE

To compare the diagnostic utility of these scores, measurements, and equations with that of visual ST-segment measurements in patients with reduced workup bias.

DESIGN

Prospective analysis.

SETTING

12 university-affiliated Veterans Affairs Medical Centers.

PATIENTS

814 consecutive patients who presented with angina pectoris and agreed to undergo both exercise testing and coronary angiography.

MEASUREMENTS

Digital electrocardiographic recorders and angiographic calipers were used for testing at each site, and test results were sent to core laboratories.

RESULTS

Although 25% of patients had previously had testing, workup bias was reduced, as shown by comparison with a pilot study group. This reduction resulted in a sensitivity of 45% and a specificity of 85% for visual analysis. Computerized measurements and visual analysis had similar diagnostic power. Equations incorporating nonelectrocardiographic variables and either visual or computerized ST-segment measurement had similar discrimination and were superior to single ST-segment measurements. These equations correctly classified 5 more patients of every 100 tested (areas under the receiver-operating characteristic curve, 0.80 for equations and 0.68 for visual analysis; P < 0.001) in this population with a 50% prevalence of disease.

CONCLUSIONS

Standard exercise tests had lower sensitivity but higher specificity in this population with reduced work-up bias than in previous studies. Computerized ST-segment measurements were similar to visual ST-segment measurements made by cardiologists. Considering more than ST-segment measurements can enhance the diagnostic power of the exercise test.

Structural constriction of the artery wall contributes to stenosis severity in unstable angina

Eight consecutive patients with unstable angina underwent intravascular ultrasound imaging of the culprit artery with measurements recorded at the stenosis and at an adjacent reference site. In all patients, total artery cross-sectional area was smaller at the stenosis site than at the reference site, indicating that a structural change in the artery wall due to a constrictive process appears to contribute to the worsening of stenosis severity associated with unstable angina.

Comparative accuracy of three automated techniques in the noninvasive estimation of central blood pressure in men

Automated devices have regularly replaced manual sphygmomanometry for the determination of blood pressure not only in homes and clinics, but also in emergency and critical care settings. Few studies exist that correctly assess the accuracy of these devices, and even fewer that specifically compare commercially available units that rely on different physiologic events for measurement. Six hundred pressure measurements were obtained from 120 subjects using 1 of 3 randomly selected blood pressure monitors. In addition, central arterial pressure measurements were obtained simultaneously and directly from the ascending aorta of each subject. Overall, these devices tended to overestimate diastolic (+2.5 mm Hg, p < 0.0001) and mean (+3.8 mm Hg, p < 0.0001) pressures, but not systolic (+0.7 mm Hg, p = NS) pressure. Compared with the other 2 devices, device I, relying on oscillometric detection, demonstrated a significantly smaller mean absolute error for diastolic pressure (4.9 +/- 3.0 vs 7.0 +/- 4.8 and 6.2 +/- 5.3 mm Hg, p < 0.0001) and mean pressure (4.0 +/- 3.2 vs 7.8 +/- 5.9 and 8.6 +/- 7.5 mm Hg, p < 0.0001), and a trend toward smaller error with systolic pressure (6.8 +/- 6.5 vs 7.3 +/- 6.8 and 8.0 +/-5.6 mm Hg, p = 0.19). Clinically significant (+/-10 mm Hg) errors were common with each device (24.8% overall), but serious (+/-20 mm Hg) errors were unusual (3.2%) and did not occur at all with device I during diastolic and mean pressure measurement. All of the devices tested could be expected to perform satisfactorily in most clinical settings provided that an average error of 4.0 to 8.6 mm Hg is tolerable. This level of accuracy typically extended throughout the range of pressures anticipated in most noncritical clinical situations. As implemented in the devices tested, noninvasive measurement by oscillometry with stepped deflation is more accurate than automated auscultation.

Composition of human thrombus assessed by quantitative colorimetric angioscopic analysis

BACKGROUND

Angioscopy surpasses other diagnostic tools, such as angiography and intravascular ultrasound, in detecting arterial thrombus. This capability arises in part from the unique ability of angioscopy to assess true color during imaging. In practice, hardware-induced chromatic distortions and the subjectivity of human color perception substantially limit the theoretic potential of angioscopic color. We used a novel application of tristimulus colorimetry to quantify thrombus color to both aid in its detection and assess its composition.

METHODS AND RESULTS

A series of human thrombus models were constructed in vitro. Spatial homogeneity was ensured by light and electron microscopy. Quantitative colorimetric angioscopic analysis demonstrated excellent measurement reproducibility (mean difference, 0.07% to 0.17%), unaffected by illuminating light intensity (coefficient of variation, 0.21% to 3.67%). Colorimetric parameters C1 and C2 were strongly correlated (r=.99, P<.0001) with thrombus erythrocyte concentration. Principal components analysis transformed these parameters into a single value, the thrombus erythrocyte index, with little (0.06%) loss of content. Measured and predicted concentrations were similar (mean difference, 0.16 erythrocytes per 1 ng). Randomly ordered images were also subjected to visual analysis by three experienced angioscopists, with suboptimal levels of both intraobserver (mean kappa=0.63) and interobserver (mean kappa=0.48) agreement. In addition, visual ranking resulted in a Kendall rank coefficient of 0.72 to 0.76 versus a perfect 1.00 from quantitative measurement.

CONCLUSIONS

Quantitative colorimetric angioscopic analysis provides a new, objective, and reproducible analytic tool for assessing angioscopic images of human thrombus. Even under ideal circumstances, experienced angioscopists do a poor job of assessing color (and therefore composition) of human thrombi. This technique can, for the first time, provide quantitative information of thrombus composition during routine diagnostic imaging.

Maintenance of hemostasis after invasive cardiac procedures: implications for outpatient catheterization

OBJECTIVES

This study investigated the efficacy of four different methods of arterial puncture site management during recovery from invasive cardiac procedures. The primary goals were less patient discomfort and improved clinical outcome.

BACKGROUND

The increasing use of outpatient catheterization, large interventional devices and potent periprocedural anticoagulation regimens has made the reduction of groin complications a high priority. Despite these trends, there are no randomized trials comparing commonly used techniques in treating the catheter entry site for the first few hours after the procedure.

METHODS

Four-hundred consecutive patients undergoing catheterization laboratory procedures were randomly assigned to one of four dressing techniques applied after achieving hemostasis: a sandbag placed over the site; a pressure dressing constructed from surgical gauze and elastic tape; a commercially available compression device; and no use of compressive dressing. Of these 400 patients, 171 would have been eligible for outpatient procedures in the absence of geographic constraints. The dressings were removed, and ambulation was encouraged 5 h after sheath removal. Uniform initial compression times, patient instructions, nursing follow-up and a structured interview and physical examination at 24 h were used.

RESULTS

The level of patient discomfort before and after dressing removal, as well as site tenderness at 24-h follow-up, was statistically similar in all four groups. Hematomas (typically small) and areas of ecchymosis were observed in 58 and 122 patients, respectively, but both their frequency and size were equally represented in each group. Important adverse events were confined to bleeding, rated as mild in 5.8%, moderate in 0.8% and severe in 0.6% of patients. Again, all four groups were statistically similar. Comparable findings were observed in the subgroup of patients eligible for outpatient procedures.

CONCLUSIONS

Despite an increase in inconvenience and expense, none of the three compression techniques that were investigated improved patient satisfaction or outcome. Therefore, the routine use of compression dressings after invasive cardiac procedures cannot be recommended.

Repeat interventions as a long-term treatment strategy in the management of progressive coronary artery disease

OBJECTIVES

This study investigates whether repeat coronary interventions, applied over an extended time period, can successfully curtail the progression of ischemic symptoms and angiographic lumen narrowing.

BACKGROUND

Coronary artery disease is a chronic and generally progressive disorder, and potential treatment strategies should be examined and compared with this chronicity in mind. Percutaneous interventional revascularization procedures could theoretically be useful in controlling progression of the disease through repeated use as new coronary lesions arise. However, the outcome of this long-term management concept has not previously been subjected to detailed investigation.

METHODS

From a consecutive series of 4,357 interventional cardiac procedures, 544 patients were identified who received two or more interventions during the 13-year study period. These patients were categorized into one of three groups: restenosis (repeat interventions limited to the same target segment, n = 261), new stenosis (all repeat interventions directed to stenoses not previously treated, n = 155) or both (repeat interventions directed both to the same and to different target lesions, n = 128).

RESULTS

Two to five procedures were performed per patient; the time period (mean +/- SD) separating each procedure was significantly less (p < 0.0001) for the restenosis group (4.2 +/- 2.3 months) than for the new stenosis (24.2 +/- 23.5 months) or the "both" groups (11.4 +/- 11.0 months). Despite the need for repeat procedures, the severity of angina (mean New York Heart Association functional class 1.6 +/- 0.9) after 6.2 +/- 2.3 years of follow-up was substantially better than before the initial procedure (mean functional class 3.2 +/- 0.8), with a similar magnitude of change found in all three groups. This long-term functional improvement was mirrored by a corresponding anatomic improvement, with the mean number of diseased vessels remaining constant at the time of each procedure (1.5 +/- 0.7, 1.5 +/- 0.7 and 1.6 +/- 0.7, respectively, for the first, second and third procedures, p = NS). The restenosis and the new stenosis groups also demonstrated statistically similar annual rates of mortality (1.9% vs. 1.8%) and coronary surgery (2.3% vs. 2.6%), although the restenosis group had a lower rate of infarction (1.4% vs. 3.2%, p = 0.002).

CONCLUSIONS

Repeat interventional treatment of newly acquired stenoses provides a rational approach for the long-term management of chronic coronary artery disease. In addition to yielding a favorable late outcome, the use of this strategy can result in sustained functional improvement and can check the progression of clinically significant stenoses.

Contributions of frequency distribution analysis to the understanding of coronary restenosis. A reappraisal of the gaussian curve

BACKGROUND

Clinical restenosis after balloon angioplasty can be categorized by use of dichotomous terms based on the presence or absence of recurrent myocardial ischemia. In contrast, recent investigations have concluded that late luminal renarrowing, documented through angiographic imaging, occurs to a variable extent in nearly all stenoses. This process has been characterized by a gaussian or normal frequency distribution, with restenosis simply representing an extreme form of this delayed remodeling. In the current study, frequency distribution analysis was used to examine the process of coronary restenosis in a large cohort of patients at risk.

METHODS AND RESULTS

Quantitative coronary angiographic analysis was applied to 9279 cineangiograms obtained in 3093 patients before and immediately after angioplasty and after 6-month follow-up. Late loss, defined as the change in minimum lumen diameter of the target stenosis from postdilation to follow-up, did not statistically conform to a normal distribution (P<.0001 by both chi2 statistic and Kolmogorov-Smirnov test), even after the exclusion of the 236 stenoses that displayed total occlusions at follow-up angiography. Examination of deviation from a normal curve revealed an excessively high frequency of stenoses that experienced either little change (0.0+/-0.3 mm) or marked change (1.0 to 2.0 mm) in late loss, with a low frequency of stenoses with intermediate values (0.3 to 1.0 mm). Similarly, although the distribution of percent diameter stenosis of the target lesion was statistically normal immediately after dilation, this gaussian distribution disappeared during the follow-up period. Other angiographic indexes of restenosis also failed to approximate a normal curve. In an attempt to improve the goodness of fit, a probabilistic model of late loss was created on the basis of deconvolution of the observed data distribution. Two theoretical, discrete populations of stenoses were identified, one with and one without overall late luminal narrowing. Unlike the gaussian distribution, this model provided a good representation of the observed data (P=NS for lack of fit).

CONCLUSIONS

The frequency distributions of angiographic indexes of restenosis often superficially resemble a gaussian curve, an appearance that is artifactually enhanced by the measurement imprecision of current quantitative techniques. Nevertheless, standard indexes of coronary restenosis fail to conform statistically to a normal distribution. The pattern of deviations observed supports the possible existence of discrete subpopulations of lesions, each with a different propensity toward the development of restenosis after coronary intervention.

Comparative validation of quantitative coronary angiography systems. Results and implications from a multicenter study using a standardized approach

BACKGROUND

Computerized quantitative coronary angiography (QCA) has fundamentally altered our approach to the assessment of coronary interventional techniques and strategies aimed at the prevention of recurrence and progression of stenosis. It is essential, therefore, that the performance of QCA systems, upon which much of our scientific understanding has become integrally dependent, is evaluated in an objective and uniform manner.

METHODS AND RESULTS

We validated 10 QCA systems at core laboratories in North America and Europe. Cine films were made of phantom stenoses of known diameter (0.5 to 1.9 mm) under four experimental conditions: in vivo (coronary arteries of pigs) calibrated at the isocenter or by use of the catheter as a scaling device and in vitro with 50% contrast and 100% contrast. The cine films were analyzed by each automated QCA system without observer interaction. Accuracy and precision were taken as the mean and SD of the signed differences between the phantom stenoses, and the measured minimal luminal diameters and the correlation coefficient (r), the SEE, the y intercept, and the slope were derived by their linear regression. Performance of the 10 QCA systems ranged widely: accuracy, +0.07 to +0.31 mm; precision, +/- 0.14 to +/- 0.24 mm; correlation (r), .96 to .89; SEE, +/- 0.11 to +/- 0.16 mm; intercept, +0.08 to +0.31 mm; and slope, 0.86 to 0.64.

CONCLUSIONS

There is a marked variability in performance between systems when assessed over the range of 0.5 to 1.9 mm. The range of accuracy, intercept, and slope values of this report indicates that absolute measurements of luminal diameter from different multicenter angiographic trials may not be directly comparable and additionally suggests that such absolute measurements may not be directly applicable to clinical practice using an on-line QCA system with a different edge detection algorithm. Power calculations and study design of angiographic trials should be adjusted for the precision of the QCA system used to avoid the risk of failing to detect small differences in patient populations. This study may guide the fine-tuning of algorithms incorporated within each system and facilitate the maintenance of high standards of QCA for scientific studies.

Effect of thrombolysis on acute mitral regurgitation during evolving myocardial infarction. Experience from the Thrombolysis in Myocardial Infarction (TIMI) Trial

OBJECTIVES

This study was undertaken to determine whether early successful thrombolysis can reverse infarct-associated mitral valve dysfunction.

BACKGROUND

Mitral regurgitation is a common complication of acute myocardial infarction and has been shown to adversely affect both short- and long-term prognosis. Although anecdotal reports have suggested that reperfusion of the infarct-related artery may restore normal function to the mitral valve, this theory has not been subjected to formal investigation.

METHODS

Patients with total or partial obstruction of the infarct-related artery received intravenous thrombolytic therapy with either streptokinase or recombinant tissue-type plasminogen activator within 7 h of symptom onset (mean 4.8 h) as part of the Thrombolysis in Myocardial Infarction (TIMI) Phase I trial. Repeat coronary angiography assessed arterial patency at 90 min and 10 days after attempted reperfusion. The presence and severity of mitral regurgitation were determined by contrast ventriculography both before thrombolysis and before hospital discharge.

RESULTS

Overall, 21 (16%) of the 132 study patients exhibited mitral regurgitation on either their initial or their predischarge ventriculogram. The proportion of infarct-related arteries found to be patent (TIMI flow grade 2 or 3) was statistically similar in patients with and without mitral regurgitation during each angiographic evaluation period (initial, 90 min and 10 days). Although coronary artery perfusion increased overall during sequential measurement (mean TIMI grade was 0.4 +/- 0.6 initially, 1.5 +/- 1.3 at 90 min and 2.2 +/- 1.0 at 10 days), the pattern of reperfusion observed could not predict an increase or decrease in regurgitant severity (p = NS). Early mitral regurgitation resolved in 57% of patients by 10 days, but this resolution appeared independent of the presence or absence of improved coronary perfusion (60% vs. 50%). The development of new regurgitation during the recovery period (6%) was also unrelated to improved perfusion (7% vs. 4%).

CONCLUSIONS

Acute mitral regurgitation developing during myocardial infarction shows frequent changes in its presence or severity during the 1st 10 days, appears independent of coronary artery patency both early and late after thrombolysis and cannot be reliably treated by improving arterial perfusion with thrombolytic agents.

Mitral regurgitation in early myocardial infarction. Incidence, clinical detection, and prognostic implications. TIMI Study Group

OBJECTIVE

To investigate mitral regurgitation occurring early in the course of acute myocardial infarction with respect to its incidence, the impact of infarct size and location, the accuracy of clinical detection, the contribution of global and regional left ventricular performance, and its influence on prognosis.

DESIGN

Prospective observational study derived from patients entering Phase I of the Thrombolysis in Myocardial Infarction (TIMI) trial.

SETTING

Multicenter trial involving 13 university-affiliated medical centers.

PATIENTS

A total of 206 patients studied within 7 hours of symptom onset during their first myocardial infarction.

MEASUREMENTS

Contrast left ventriculography was used to document mitral regurgitation.

RESULTS

Mitral regurgitation was present in 27 patients (13%). Although the presence of regurgitation correlated with the site of infarction (20 of 27 had anterior infarctions) and the number of akinetic chords, it was not statistically related to the peak creatine kinase value or to left ventricular chamber size or filling pressure. A murmur of mitral regurgitation was heard in only 2 patients (1 incorrectly). The presence of early mitral regurgitation predicted cardiovascular mortality at 1 year by univariate (relative risk, 12.2; 95% Cl, 3.5 to 42; P less than 0.0001) and multivariate (relative risk, 7.5; Cl, 2.0 to 28.6; P = 0.0008) analyses.

CONCLUSIONS

Mitral regurgitation in early myocardial infarction is generally clinically "silent," is more common in anterior infarction, is associated with regional dysfunction but not early ventricular dilation or peak enzyme release, and is an important predictor of cardiovascular mortality.

Catheter optimization during contrast ventriculography: a prospective randomized trial

Although newer contrast mediums have improved hemodynamic stability during left ventriculography, the image quality and hence the diagnostic yield of the procedure is largely determined by the choice of catheter and injection technique. In this study 125 patients were prospectively assigned at random to undergo ventriculography using either of two pigtail catheters, one with a straight shaft throughout its length (straight) and one with a 145-degree bend placed 6.5 cm from the distal end (angled). Injectate composition, flow rate, and volume were held constant for all injections, and baseline clinical and catheterization variables were found to be similar in each group. The angled catheter exhibited a statistically superior ease of insertion (p = 0.038) and took less time to position (p = 0.012), saving a mean of 23 seconds of fluoroscopy time per procedure. It was also associated with superior contour edge definition (p = 0.037) and a trend toward more uniform distribution of contrast medium (p = 0.089). Compared with the straight catheter, the angled catheter was less frequently accompanied by artifactual mitral regurgitation (p = 0.038) but was equally likely to provoke ventricular arrhythmias during injection. These observed differences may be explained in part by the tendency for angled catheters to more frequently localize in the central as opposed to the inferoposterior region of the left ventricular cavity (mean distance from center = 0.53 vs 1.10 cm, respectively; p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Usefulness of exercise-induced ST-segment depression in the inferior leads during exercise testing as a marker for coronary artery disease

Multiple lead systems are shown to have a higher sensitivity than that of single leads for detecting coronary artery disease (CAD) during exercise testing, but the value of ST-segment depression isolated to the inferior leads is questionable. To ascertain the diagnostic accuracy of inferior limb lead II compared with that of precordial lead V5, a retrospective analysis of 173 men was performed (108 in a training population and 65 in a validation cohort). All patients had a standard exercise test and underwent diagnostic coronary angiography within 15 days of the exercise test (range 1 to 65). Sixty-three patients had greater than or equal to 1 coronary stenoses greater than or equal to 70%, or left main lesion greater than or equal to 50%, whereas 45 patients in the training population did not. Exclusion criteria were female sex, left ventricular hypertrophy, left bundle branch block or resting ST-segment depression on the baseline electrocardiogram, previous myocardial infarction or revascularization procedures, and any significant valvular or congenital heart disease. Lead V5 had a better combination of sensitivity (65%) and specificity (84%) (chi-square = 24.11; p less than 0.001) than that of lead II (sensitivity 71%, specificity 44%) (chi-square = 2.25; p = 0.13) at a single cut point, and this improved specificity was substantial (95% confidence interval for observed difference 22 to 58%). Receiver-operating characteristic curve analysis also revealed that lead V5 (area = 0.759) was markedly superior to lead II (area = 0.582) over multiple cut points (z = 3.032; 2p = 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation between resting ST segment depression, exercise testing, coronary angiography, and long-term prognosis

Resting ST segment depression has been identified as a marker for adverse cardiac events in patients with and without known coronary artery disease. To correlate this with exercise testing, coronary angiography, and how it impacts on long-term prognosis, a retrospective study was performed on 476 patients, of whom 223 had no clinical or electrocardiographic evidence of prior myocardial infarction while 253 were survivors of an infarction. All patients performed a standard exercise test and underwent diagnostic coronary angiography within an average of 32 days of their exercise test (range 0 to 90 days). Exclusions were women, those with left bundle branch block, left ventricular hypertrophy, use of digoxin, previous revascularization procedures, or significant valvular or congenital heart disease. Long-term follow-up was carried out for an average of 45 months (+/- 17). Of the patients without prior infarction, 23 (10%) had persistent resting ST segment depression, and of those with a prior history of infarction, 37 (15%) also had resting ST segment depression. Patients with resting ST segment depression and no prior myocardial infarction had a higher prevalence of severe coronary disease (three-vessel and/or left main) (30%) than those without resting ST segment depression (16%) (95% confidence interval [CI] for observed difference -5.0% to 33.9%, p = 0.12). The criterion of greater than or equal to 2 mm of additional exercise-induced ST segment depression was a particularly useful marker in these patients for the diagnosis of any coronary disease (likelihood ratio 3.35, 95% CI 0.56 to 19.93, p = 0.06). Patients with resting ST segment depression and a prior myocardial infarction had a 2.5 times higher prevalence of severe coronary artery disease compared with patients without resting ST segment depression (43% versus 17% prevalence, respectively, 95% CI for observed difference 9.38% to 42.8%, p less than 0.001) and also had larger left ventricles postinfarction (left ventricular end-diastolic volume index 102 ml/m2 compared with 96 ml/m2, p less than 0.001).(ABSTRACT TRUNCATED AT 400 WORDS)

Post-myocardial infarction exercise testing. Non-Q wave versus Q wave correlation with coronary angiography and long-term prognosis

BACKGROUND

The presence or absence of baseline diagnostic Q waves has been believed to compromise the accuracy of standard exercise electrocardiography in identifying severe coronary artery disease (three-vessel and/or left main disease); therefore, a retrospective analysis was performed using a personal computer data base of exercise test responses and cardiac catheterization results to evaluate this premise, and follow-up was performed to observe how Q waves and/or severe coronary disease impacted on survival.

METHODS AND RESULTS

Two hundred fifty-three male patients who had survived a myocardial infarction were studied. Patients on digitalis, those with left bundle branch block or left ventricular hypertrophy on their baseline electrocardiogram, those with previous revascularization procedures, and those with significant valvular or congenital heart disease were excluded. All patients performed either a low-level predischarge or a sign/symptom limited exercise test and underwent diagnostic coronary angiography within 32 days of each test (range, 0-90 days). Long-term follow-up on patients was performed for an average of 45 months (+/- 17 months). Group NQMI comprised 103 post-myocardial infarction patients lacking Q waves at the time of exercise testing and group QMI comprised 150 patients who developed Q waves with their myocardial infarction. The cut points of greater than or equal to 1 mm (chi 2 = 14.39, p less than 0.001) and greater than or equal to 2 mm (chi 2 = 26.11, p less than 0.001) of exercise-induced ST segment depression were reliable markers of severe coronary disease in Q wave infarct survivors. This was also true for non-Q wave infarct survivors as greater than or equal to 1 mm (chi 2 = 6.02, p = 0.01) and greater than or equal to 2 mm (chi 2 = 4.37, p = 0.04) of ST segment depression were reliable markers of severe coronary disease. Receiver operating characteristic curve analysis revealed that exercise-induced ST segment depression had discriminating power for the identification of severe coronary artery disease in both the Q wave myocardial infarction patients (area = 0.735, z = 4.47, p less than 0.001) and the non-Q wave infarct patients (area = 0.700, z = 3.20, p less than 0.001). After 4.4 years of cumulative follow-up, patients with severe coronary disease had an infarct-free survival rate of 72% (95%, CI, 50.0-86.0%), whereas those without severe disease had an 86% (95% CI, 76.5-91.5%) infarct-free survival rate (Cox chi 2 = 4.00, p = 0.045). Non-Q wave patients had an infarct-free survival rate of 81% (95% CI, 66.0-89.5%), whereas those with Q waves had an infarct-free survival rate of 85% (95% CI, 73.9-91.3%) (Cox chi 2 = 0.0005, p = NS).

CONCLUSIONS

The presence or absence of diagnostic Q waves has no significant effect on the ability of the exercise electrocardiogram to identify severe coronary artery disease in survivors of myocardial infarction. Long-term infarct-free survival of patients with myocardial infarction is more related to the presence of severe coronary disease rather than if they suffered a non-Q wave or Q wave infarction.

Effect of beta-blockade on the interpretation of the exercise ECG: ST level versus delta ST/HR index

The diagnostic value of exercise-induced ST segment depression is considered to be decreased in patients receiving beta-blockers. One approach to improving predictive accuracy has been to use the ratio of maximal change in exercise-induced ST segment depression to the corresponding maximal change in heart rate (delta ST/HR index). The present study compared these two ECG methods. The records of exercise tests performed on 3047 male veterans were screened to exclude patients with prior revascularization procedures or myocardial infarction, those receiving digoxin, and those with certain resting ECG abnormalities; the use of beta-blocker drugs at the time of testing was also noted. All exercise tests were sign/symptom limited. Significant angiographic coronary disease was defined as greater than or equal to 75% reduction in luminal diameter of at least one coronary artery. Disease severity was evaluated in an expanded study group that included patients with prior myocardial infarction. Mean maximal heart rate was 21 beats.min-1 lower for those receiving beta-blockers (p less than 0.05), but there was no difference in mean metabolic equivalent (MET) level achieved. The diagnostic accuracy of an abnormal test result for determination of the presence or absence of coronary artery disease was not significantly different in the subgroup taking beta-blockers versus the subgroup not taking beta-blockers (N = 200), and use of the delta ST/HR index did not improve test performance. For discrimination of severe disease, test accuracy was also unaffected by beta-blockers and was not improved by the delta ST/HR index (N = 454).(ABSTRACT TRUNCATED AT 250 WORDS)

Restenosis rate after percutaneous transluminal coronary angioplasty: a literature overview

In order to elucidate factors affecting the rate of angioplasty restenosis, we reviewed 212 published reports on restenosis after percutaneous transluminal coronary angioplasty. We used five specific methodologic standards to select the 31 reports most likely to produce unbiased results. Sixty one factors judged to be related to restenosis rate were investigated. Only shorter duration of data collection (p=0.0003) was related to higher restenosis rate. This factor may be related to inexperience in choosing subjects or performing procedures. Other factors whose association with restenosis rate did not reach our predetermined level of statistical significance (p less than .01) were angioplasties of the left circumflex artery (p=.02), angioplasty of total occlusions (p=.02) and advanced age (p=.05). The association of shorter data collection with higher restenosis rates suggests that improved outcome may result from consolidation to a few centers specializing in this technique.

Comparison of silent and symptomatic ischemia during exercise testing in men

OBJECTIVE

To compare angina and ST-segment depression during exercise testing, as markers for coronary artery disease.

DESIGN

Retrospective analysis of exercise test responses and cardiac catheterization results.

SETTING

A U.S. Veterans Affairs medical center.

PATIENTS

Four hundred and sixteen men who were referred for the evaluation of symptoms, postmyocardial infarction testing, or both. Two hundred patients had no clinical or electrocardiographic evidence of previous myocardial infarction, whereas 216 were survivors of a previous myocardial infarction.

INTERVENTIONS

All patients did a standard exercise test and had diagnostic coronary angiography with ventriculography within an average of 32 days (range, 0 to 90 days) of their exercise test.

RESULTS

Two hundred patients without a previous myocardial infarction were divided into four groups: the no ischemia group had 80 patients; the angina pectoris only group had 23 patients; the silent ischemia group had 40 patients; and the ST-segment depression and angina pectoris group had 57 patients. In patients without a previous myocardial infarction, exercise-induced ST-segment depression was a better marker than exercise-induced angina for the presence of any coronary artery disease (P less than 0.005). Patients with symptomatic exercise-induced ischemia had a higher prevalence of severe coronary artery disease than did those with only silent ischemia (30% compared with 20%; 95% CI, - 7.3% to 27.0%; P = 0.005). For the 216 survivors of a myocardial infarction, divided into the same four groups, ST-segment depression again was a better marker for the presence of severe coronary artery disease compared with angina alone (P = 0.08). The prevalence rates of severe coronary artery disease in the no ischemia plus myocardial infarction group, the angina pectoris only plus myocardial infarction group, the silent ischemia plus myocardial infarction group, and the ST-segment depression and angina pectoris plus myocardial infarction group were 10%, 9%, 23%, and 32%, respectively (P less than 0.01).

CONCLUSIONS

Exercise-induced ST-segment depression is a better marker for coronary artery disease than is exercise-induced angina. Symptomatic ischemia during the exercise test is a better marker for severe coronary artery disease than is silent ischemia.

Onset of altered interventricular septal motion during cardiac surgery. Assessment by continuous intraoperative transesophageal echocardiography

Abnormal motion of the interventricular septum is frequently observed after uncomplicated cardiac surgery. We sought to elucidate the mechanism underlying this phenomenon by using continuous echocardiographic imaging of the heart from a constant transesophageal location in 21 patients undergoing their first cardiac operation. Quantitative global and regional functional analyses were performed in each patient at baseline (stage 1), after median sternotomy (stage 2), after sternal retraction (stage 3), after pericardiotomy (stage 4), after completion of cardiopulmonary bypass (stage 5), and after chest closure (stage 6). During the first four surgical stages, mean left ventricular fractional shortening varied little among regions with a fixed reference system (maximum range, 31.6-39.2%; p = NS) but changed dramatically after the discontinuation of cardiopulmonary bypass (stage 5). The apparent medial hypokinesis that was observed (4.9 +/- 4.7% [SD]) was accompanied by lateral hyperkinesis (65.2 +/- 4.1%, p less than 0.0001). These regional differences were completely eliminated with a floating reference system (33.6 +/- 2.7% for medial, and 34.8 +/- 1.7% for lateral; p = NS), suggesting cardiac translation. Quantitative curvature analysis supported this conclusion, with preservation of baseline regional curvature seen throughout the procedure. The mean length of individual translational vectors (reflecting systolic movement of the endocardial centroid) remained minimal (less than or equal to 1.0 mm) through stage 4 but increased more than fourfold at stage 5, continuing in a medial direction after chest closure (5.2 +/- 3.0 mm and 271 +/- 6 degrees from anterior). Thus, abnormal postoperative septal motion is not caused by removal of restraining forces of the pericardium or anterior mediastinum but rather appears to be directly related to events occurring during cardiopulmonary bypass.

Comparison of ST segment/heart rate index to standard ST criteria for analysis of exercise electrocardiogram

The objective of our study was to compare the discriminating power of a proposed ST segment/heart rate index with that of a standard method of assessing exercise-induced ST segment depression for diagnosing coronary artery disease. We used a cross-sectional retrospective analysis of exercise test and coronary angiographic data. The study took place in a 1,200-bed Veterans Affairs Medical Center; participants were 328 male patients who had undergone both a sign and symptom-limited treadmill test and coronary angiography. The sensitivity of the ST segment/heart rate index was 54% at a cut point of 0.021 mm/(beats/min), corresponding to a specificity of 73%. The standard visual ST segment analysis had a sensitivity of 58% at this same specificity, which corresponded to an ST segment cut point of 1-mm depression relative to rest (p = NS). Similarly, for diagnosing three-vessel or left main coronary disease, no significant difference was found between the sensitivities or the two measurements at cut points of equivalent specificity. In this consecutive series of patients presenting for routine clinical testing, the ST segment/heart rate index did not improve the diagnostic accuracy of the exercise test for identifying the presence or severity of coronary artery disease relative to standard visual criteria.

"Recovery only" ST-segment depression and the predictive accuracy of the exercise test

STUDY OBJECTIVE

To clarify the predictive value of exercise-induced ST-segment depression occurring in recovery only, and to determine whether the addition of recovery data improves the interpretation of the exercise test.

DESIGN

Retrospective analysis of data collected during exercise testing and coronary angiography.

SETTING

A 1000-bed Veterans Affairs Medical Center.

PARTICIPANTS

The study included 328 male patients who had had both a sign- or symptom-limited treadmill test and coronary angiography.

MEASUREMENTS AND MAIN RESULTS

Of the 168 patients who had abnormal ST-segment responses, 26 had such responses only during recovery. The positive predictive value of this pattern for significant angiographic disease (84%) was not statistically different from the predictive value of ST depression occurring during exercise (87%). Inclusion of ST depression during recovery significantly increased the sensitivity of the exercise test from 50% to 59% (P = 0.01) without a change in predictive value. In addition, ST-segment depression occurring only during exercise is usually associated with less-severe angiographic coronary artery disease.

CONCLUSION

The occurrence of ST-segment depression during the recovery period only, does not generally represent a "false-positive" response. The inclusion of findings from this period increases the diagnostic yield of the exercise test. Previously proposed exercise test scores, as well as exercise electrocardiography (ECG) analysis done in conjunction with scintigraphy, have a falsely lowered sensitivity that could be increased by considering ST-segment changes occurring in recovery.

Altered ventricular repolarization in central sympathetic dysfunction associated with spinal cord injury

Complete injury to the cervical spinal cord results in total disruption of central sympathetic outflow. Although ventricular repolarization can be significantly influenced by disorders of autonomic function, the effects of cervical sympathectomy are unknown. Therefore, 40 subjects with complete chronic spinal cord injury were prospectively divided into 2 groups, half with total disruption of central sympathetic outflow (level of injury C5 to C8) known as the high level injury group, and half with nearly intact sympathetic innervation (T10 to L1) serving as controls. The completeness of autonomic dysfunction was verified by the cold pressor response. ST-segment analysis of the resting surface electrocardiogram revealed multilead ST elevation in the high level injury group, with maximum ST height significantly higher than the control group (131 +/- 21 [standard error] vs 47 +/- 8 microV; p = 0.0005). Unlike the control subjects, maximal arm ergometry exercise in the high level injury subjects failed to decrease ST-segment height (delta ST = -3 +/- 6 vs -43 +/- 14 microV in controls; p = 0.02). This difference persisted even after matching for exercise capacity. However, during exogenous stimulation with the sympathomimetic amine isoproterenol, ST-segment height in the high level injury group markedly decreased (mean delta ST = -84 +/- 26 vs -17 +/- 18 microV in controls; p = 0.04). Thus, central sympathetic dysfunction regularly results in multilead ST-segment elevation that decreases to or below isoelectric baseline during low dose isoproterenol infusion. Unlike normal subjects and individuals with normal variant ST-segment elevation, ST height is not altered by exercise. These findings document that ST-segment height in man is greatly influenced by central sympathetic nervous activity both at baseline and during physiologic and pharmacologic stress.

Prevalence of catheter-induced valvular regurgitation as determined by Doppler echocardiography

It has been suggested that cardiac catheters traversing competent heart valves may induce valvular regurgitation. To evaluate this possibility, continuous-wave and pulsed Doppler echocardiographic studies were performed immediately before, during and immediately after removal of various catheters in a total of 47 adult patients without clinical evidence of valvular regurgitation. With the tip of a 7Fr balloon flotation catheter positioned in the pulmonary artery, 9 of 36 patients (25%) had pulmonary regurgitation documented by continuous-wave Doppler. Evidence for regurgitation by pulsed Doppler examination was noted in 4 of these 9, with the regurgitant signal extending a mean of 1.8 cm into the right ventricular outflow tract. Similarly, a tricuspid regurgitant signal was present in 10 of 37 patients (27%) by continuous-wave Doppler and in 6 of these 10 by pulsed Doppler, with a mean regurgitant signal depth of 2.3 cm. Doppler examination also was performed in 7 patients (2 with aortic regurgitation) with a 7Fr pigtail catheter across the aortic valve, and in 4 patients (1 with tricuspid regurgitation) with a 6Fr bipolar pacing catheter across the tricuspid valve. Catheter removal resulted in no change in either the presence or absence of a regurgitant signal, or in the regurgitant signal depth in any of the patients studied. It is concluded that standard cardiac catheters neither induce Doppler-detected valvular regurgitation, nor do they affect the retrograde distance to which an existing regurgitant signal can be mapped.

Reduction of ventricular arrhythmias by atropine during coronary arteriography

Sustained ventricular arrhythmia is a well-recognized complication of cardiac catheterization, often occurring after selective coronary artery injection of contrast medium. The role of autonomic reflexes in the pathogenesis of this phenomenon is unclear. Although the muscarinic antagonist atropine is often administered prophylactically before coronary angiography to reduce the likelihood of sinus bradycardia and vasovagal reactions, its influence on ventricular arrhythmias in this setting has not been established. This case-control trial studied 648 patients undergoing coronary arteriography to investigate this issue. Eleven case subjects (those with ventricular tachyarrhythmia) were identified. Control subjects (those without ventricular tachyarrhythmia) were matched for baseline heart rate (+/- 6 beats/min), age (+/- 10 years), sex and calendar year of procedure using a 1:3 sampling ratio. All 26 potential clinical, anatomic and hemodynamic covariates were statistically similar between groups. Ventricular tachyarrhythmias were more likely to occur after selective right coronary injection (odds ratio 15.1, p = 0.0008) but not after multiple contrast injections (odds ratio 0.918, difference not significant). Most importantly, atropine sulfate was administered prophylactically to 18 of 33 control subjects (55 +/- 9%) but only 1 of 11 cases (9 +/- 9%), generating a significant odds ratio of 12.0 (p = 0.02). Thus, the odds of experiencing sustained ventricular tachyarrhythmias during coronary arteriography may potentially be reduced 12-fold by prior administration of atropine, even in patients with normal baseline heart rates.

Autologous blood perfusion for myocardial protection during coronary angioplasty: a feasibility study

During coronary angioplasty, inflation of the balloon within the coronary artery produces transient arterial occlusion and frequently results in myocardial ischemia. Delivery of oxygenated autologous blood to the myocardium at risk during inflation may help mitigate this ischemia. Accordingly, we investigated the feasibility and safety of infusing blood through the central lumen of a dilatation catheter around the guidewire using both a model in vitro and clinical trials. In the tests in vitro, fresh blood was infused at flow rates up to 120 ml/min. Hemolysis was minimal at flow rates of 60 ml/min or less (less than or equal to 0.92 +/- 0.18%), but increased exponentially at higher rates (13.64 +/- 2.37% at 120 ml/min, p less than .002). A similar pattern was observed for potassium release. Platelet and leukocyte counts did not vary significantly, and beta-thromboglobulin and muramidase remained at control levels. Although mean erythrocyte volume did not change, erythrocyte histograms and light microscopy demonstrated a subpopulation of red cell fragments averaging 25 to 40 fl in size at higher rates. A randomized, crossover clinical trial was next performed by delivery of blood perfusion at 60 ml/min to 15 patients undergoing coronary angioplasty. Levels of plasma hemoglobin, beta-thromboglobulin, lactate dehydrogenase, and potassium remained constant before and after the perfusion and the control inflations. The maximum pain score was significantly lower with the perfusion inflation (4.1 +/- 0.8 vs 6.0 +/- 0.9, p less than .003). Relative to baseline, the maximum ST segment elevation during the perfusion inflation (0.5 +/- 0.3 mm) was nearly one-fourth that during the control inflation (1.9 +/- 0.6 mm, p less than .02). Thus, myocardial protection with oxygenated autologous blood perfusion at rates of 60 ml/min appears to be a safe and effective technique that may permit increased inflation time and extend the range of coronary angioplasty to include individuals at high risk for the procedure.

Cardiovascular abnormalities accompanying acute spinal cord injury in humans: incidence, time course and severity

The frequency of cardiovascular abnormalities was evaluated in 71 consecutive patients with acute injury to the spinal cord. Persistent bradycardia was universal in all 31 patients with severe cervical cord injury and less common in milder cervical injury (6 of 17) or thoracolumbar injury (3 of 23) (p less than 0.00001). Marked sinus slowing (71 versus 12 versus 4%, respectively, p less than 0.00001), hypotension (68 versus 0 versus 0%, p less than 0.00001), supraventricular arrhythmias (19 versus 6 versus 0%, p = 0.05) and primary cardiac arrest (16 versus 0 versus 0%, p less than 0.05) were significantly more frequent in the severe cervical injury group. The frequency of bradyarrhythmias peaked on day 4 after injury and gradually declined thereafter. All observed abnormalities resolved spontaneously within 2 to 6 weeks. The primary mechanism underlying these observations appears to involve the acute autonomic imbalance created by the disruption of sympathetic pathways located in the cervical cord. Acute severe injury to the cervical spinal cord is regularly accompanied by arrhythmias and hemodynamic abnormalities not found with thoracolumbar cord trauma. These abnormalities are limited to the first 14 days after injury, a period in which life-threatening disturbances must be anticipated.

Right atrial-esophageal fistula and hydropneumopericardium after esophageal dilation

Esophagoatrial fistula formation is a rare and heretofore fatal event. A patient presented with esophageal reflux and stricture that later developed into a right atrial-esophageal fistula during biweekly esophageal dilation. Clinical recognition and surgical therapy led to a successful outcome. There were several unique features of this case, including fistulous connection to the right rather than the left atrium, concomitant hydropneumopericardium and esophagoatrial fistula, occurrence during esophageal dilation and surgical cure.

Mitral valve E point-septal separation as an index of left ventricular function with valvular heart disease

Echocardiographic mitral valve E point-septal separation (EPSS) has been found to be a useful hemodynamic index. Prior studies have shown a high negative correlation between EPSS and left ventricular ejection fraction (EF) in selected patients, but the utility of this index with valvular heart disease has not been examined in detail. Cardiac catheterization and M-mode echocardiographic data were retrospectively analyzed from 30 patients with aortic stenosis, 18 patients with chronic aortic regurgitation, and 25 patients with chronic mitral regurgitation. For aortic stenosis patients (including those with coronary artery disease), an excellent correlation (r = -0.89, p less than 0.001) was observed between EPSS and angiographic EF. More modest correlations were noted for patients with aortic regurgitation (r = -0.58, p less than 0.01) and mitral regurgitation (r = -0.63, p less than 0.001). For patients with aortic regurgitation, correlation improved to r = -0.83 by excluding subjects with marked (greater than 4 mm) fluttering of the anterior mitral valve leaflet. For patients with mitral regurgitation, the EPSS-EF correlation improved to r = -0.72 after excluding patients with atrial fibrillation. Compared with other echocardiographic indices of left ventricular function (percent shortening of the minor diameter or echo-derived EF), the EPSS demonstrated an equivalent or superior correlation with angiographic EF for each valvular lesion studied. We conclude that EPSS is a highly reliable index of left ventricular function with aortic stenosis, but its utility in unselected patients with chronic mitral or aortic regurgitation is limited.