Is peripheral arterial pressure a satisfactory substitute for ascending aortic pressure when measuring aortic valve gradients?

Substitution of peripheral arterial pressure for ascending aortic pressure is a common but poorly validated practice in the assessment of aortic valve gradients by catheterization. The accuracy of this practice was assessed by comparing the left ventricular-ascending aortic mean gradient in 26 cases of aortic stenosis with the left ventricular-femoral artery gradient, both with and without compensation for temporal delay in femoral artery pressure. Aligned left ventricular-femoral artery gradients (matching upstrokes to compensate for peripheral time delay) underestimated the left ventricular-ascending aortic gradient by 10 mm Hg (range 0 to -17). Unaltered simultaneous left ventricular-femoral artery gradients overestimated the left ventricular-ascending aortic gradient by an average of 9 mm Hg (range +1 to +18). For both peripheral techniques, the error was relatively constant throughout the range of aortic valve gradients. The most accurate estimate of both aortic valve gradient and area was obtained by averaging the gradients and areas derived from aligned and unaltered left ventricular-peripheral arterial simultaneous tracings. Although only occasionally critical for clinical decision-making, these errors may be overwhelming in certain types of research applications, such as comparisons of valve prosthesis gradients and serial evaluations of aortic stenosis. An additional source of error is a coexistent peripheral arterial gradient that was present in 21% of otherwise technically suitable patients in the screened study group.

Percutaneous transluminal coronary angioplasty versus medical therapy for stable angina pectoris: outcomes for patients with double-vessel versus single-vessel coronary artery disease in a Veterans Affairs Cooperative randomized trial. Veterans Affairs ACME InvestigatorS.

OBJECTIVES: This study sought to assess outcomes of men with double-vessel coronary artery disease randomly assigned to treatment by percutaneous transluminal coronary angioplasty (PTCA) or medical therapy, compared with previously reported outcomes for men with single-vessel disease. BACKGROUND: We previously reported that PTCA provides better symptom relief and treadmill performance than medical therapy for men with stable angina pectoris due to single-vessel disease. Whether this advantage applies to patients with double-vessel disease is unknown. METHODS: Male patients (n = 328) with stable angina pectoris and ischemia on treadmill testing were randomly assigned to PTCA or medical therapy; 101 patients had double-vessel disease, and 227 had single-vessel disease. Symptoms, treadmill performance, quality of life score, coronary stenosis and myocardial perfusion were compared at baseline and at 6 months. Patients were followed up for up to 6 years and underwent additional treadmill testing 2 to 3 years after randomization. RESULTS: PTCA-treated and medically treated patients with double-vessel disease experienced comparable improvement in exercise duration (+1.2 vs. +1.3 min, respectively, p = 0.89), freedom from angina (53% and 36%, respectively, p = 0.09) and improvement of overall quality of life score (+1.3 vs. +4.4, respectively, p = 0.32) at 6 months compared with baseline. This contrasts with greater advantages favoring PTCA by these criteria in patients with single-vessel disease (p = 0.0001 to 0.02). Trends present at 6 months persisted at late follow-up. Patients undergoing double-vessel dilation had less complete initial revascularization (45% vs. 83%) and greater average stenosis of worst lesions at 6 months (74% vs. 56%). Likewise, patients with double-vessel disease showed less improved myocardial perfusion imaging (59% vs. 75%). CONCLUSIONS: PTCA is beneficial in male patients with double-vessel disease; however, we cannot demonstrate the same advantage over medical therapy seen in similar patients with single-vessel disease. Less complete revascularization and greater restenosis for patients having multiple dilations would account for these findings. Alternatively, a type 2 error might be operative. Technical advances since completion of this trial might improve these outcomes. These findings warrant further investigation in a larger trial.

Evaluation of exercise thallium scintigraphy versus exercise electrocardiography in predicting survival outcomes and morbid cardiac events in patients with single- and double-vessel disease. Findings from the Angioplasty Compared to Medicine (ACME) Study.

OBJECTIVES: We sought to evaluate the prognostic ability of cardiac exercise stress tests in predicting cardiac mortality and morbidity in a low risk group of patients with established coronary artery disease (CAD). BACKGROUND: Although previous studies have demonstrated the superior value of stress nuclear cardiac scintigraphy in the prognosis of patients with CAD, none of these studies have focused on patients with a proven angiographic low risk profile (i.e., single- and double-vessel CAD). METHODS: Three hundred twenty-eight patients with documented single- and double-vessel disease were treated by random assignment to percutaneous transluminal coronary angioplasty or medical therapy in the Angioplasty Compared to Medicine (ACME) trial. Six months after randomization, maximal symptom-limited exercise tests were performed with electrocardiography (n = 300) and thallium scintigraphy (n = 270). Patients were followed up for a minimum of 5 years thereafter. RESULTS: A reversible thallium perfusion deficit documented after 6 months of either therapy was associated with an adverse mortality outcome (18% mortality rate with a reversible thallium perfusion defect and 8% mortality rate with no reversible thallium perfusion deficit, p = 0.02). Moreover, an important mortality gradient was demonstrated in relation to the number of reperfusing defects (0 = 7%, 1 to 2 = 15%, >3 = 20%, p = 0.04). Exercise electrocardiography did not predict this mortality outcome. CONCLUSIONS: A reversible thallium perfusion deficit demonstrated 6 months after medical therapy or coronary angioplasty is a valuable prognostic marker in patients with angiographically documented single- and double-vessel disease and is superior to exercise electrocardiography in this regard.

Intraaortic balloon counterpulsation as a temporary support measure in decompensated critical aortic stenosis.

Intraaortic balloon counterpulsation was instituted in two adult patients whose condition was rapidly deteriorating because of critical decompensated valvular aortic stenosis. The acute hemodynamic effect of counterpulsation in these patients was compared with the effect of counterpulsation in three control patients with unstable angina and no aortic valve disease. Augmentation of aortic diastolic pressure was similar in both groups; however, in contrast to the patients with unstable angina, the patients with aortic stenosis had no decrease in left ventricular systolic pressure. Counterpulsation resulted in an increase in the transvalvular pressure gradient, which was associated with a slight increase in stroke volume. In both patients with aortic stenosis, the institution of counterpulsation resulted in marked clinical improvement, which facilitated successful valve replacement surgery. The benefit from counterpulsation in critically decompensated aortic stenosis appears to be derived almost entirely from augmentation of the diastolic coronary filling gradient. The improvement that results from counterpulsation suggests that ischemia is the major cause of decompensation.

Six month postoperative hemodynamics of the Hancock heterograft and the Björk-Shiley prosthesis: results of a Veterans Administration cooperative prospective randomized trial.

In a Veterans Administration Cooperative Study involving 13 medical centers, 575 patients undergoing single valve replacement were prospectively randomized to receive either the standard Björk-Shiley prosthesis or the Hancock porcine heterograft (with a modified orifice for sizes 23 and smaller). The hemodynamic data in the 268 patients who underwent cardiac catheterization an average of 6 months (range 3 to 12) postoperatively are reported. Statistical analyses were performed on valve sizes 23, 25 and 27 in the aortic position, and 29, 31 and 33 in the mitral position. A wide variation was observed in mean pressure gradient and calculated orifice area in both valve types within all sizes in both the aortic and the mitral positions. In the aortic position, the Björk-Shiley prosthesis tended to have a lower pressure gradient and larger calculated orifice area than the Hancock heterograft, but the differences in gradient between the two valve types were significant only in the larger-sized valves. The difference in calculated area between the two valve types was not significant within each valve size. In the mitral position, there were no differences in gradient and calculated orifice area between the two types of prostheses. The postoperative cardiac index, regurgitant volume, pulmonary artery systolic and mean pressures, left ventricular end-diastolic pressure, left ventricular ejection fraction and left ventricular end-diastolic volume index did not differ in patients receiving the Björk-Shiley prosthesis from values in patients receiving the Hancock heterograft. Hence, the overall hemodynamic performance of both types of valves is remarkably similar. The choice between these two prostheses should, therefore, be governed not by the hemodynamic performance, but by other factors such as valve durability, risk of anticoagulation and incidence of valve-related complications.

Physician extenders in walk-in clinics: a prospective evaluation of the AMOSIST program.

The Automated Military Outpatient System (AMOS) Project was developed to improve the ambulatory care of patients with episodic and chronic illnesses. During the development of its episodic care component, the relative frequency of problems treated by the walk-in clinic staff was analyzed and showed a high volume of acute minor illnesses. A simple, conservative triage system run by non-professionals was developed to screen patients to a clinic for benign, self-limited illnesses run by physician-extenders. This group, the equivalent of civilian licensed practical nurses and nurses' aides, was trained in a task-oriented fashion to treat 44 common minor illnesses. Clinical algorithms for these illnesses were developed and used as training tools, memory aids, and auditing instruments. This program is now operating in 26 US Army hospitals and caring for some 44,000 patients a month in the continetal United States. We report the results of a prospective audit of the corpsmen and a study of the patient attitude and acceptance of the program.

The radionuclide ejection fraction: a comparison of three radionuclide techniques with contrast angiography.

Left-ventricular ejection fraction (EF) can be measured by several radionuclide methods. The EFs determined by three such methods (first-transit time-activity, equilibrium blood-pool time-activity, and equilibrium blood-pool area-length) were compared in 30 patients with EFs measured by area-length analysis of x-ray contrast angiograms. Both time-activity methods (first-transit and blood-pool) yielded EFs that correlated well with x-ray contrast EFs (r=0.86 and 0.84, respectively). Area-length analysis of blood-pool images yielded EFs that agreed less well with x-ray contrast EFs (r=0.73 in the RAO view, 0.70 in the LAO view). We conclude that first-transit and blood-pool techniques are equally accurate methods for determining EF when the time-activity method of analysis is employed.

Programmed electrical stimulation of the heart in coronary artery disease.

The induction of ventricular arrhythmia in patients with a history of malignant ventricular arrhythmia by programmed electrical stimulation (PES) is associated with a poor prognosis. However, the incidence and significance of inducible arrhythmia in patients with stable coronary artery disease (CAD) who do not have a history of serious arrhythmia are unknown. We studied 32 such patients (31 men, mean age 55 years) with PES at the time of cardiac catheterization. Fourteen patients (Group I) manifested greater than or equal to 3 extraventricular responses when challenged with 1 to 3 propagated right ventricular extrastimuli during ventricular pacing. Twelve (86%) of these 14 had evidence of left ventricular dysfunction (LVD), defined by a global ejection fraction of less than 50% or regional wall motion abnormalities. The remaining 18 patients (Group II) manifested less than or equal to 2 responses to extrastimulation. Only 4 (22%) of these 18 had LVD. Proximal 3-vessel CAD was more frequent in Group I patients (10 of 14, 71%) than in Group II (7 of 18, 39%). Only 5 patients (4 from Group I and 1 from Group II) demonstrated complex arrhythmia during exercise testing or ambulatory monitoring. The induction of extraventricular responses during PES may serve as an independent marker of electrical instability in the coronary population and is a much more common finding in those with LVD.

Two- to three-year follow-up of patients with single-vessel coronary artery disease randomized to PTCA or medical therapy (results of a VA cooperative study). Veterans Affairs Cooperative Studies Program ACME Investigators. Angioplasty Compared to Medicine.

Despite increasing use of percutaneous transluminal coronary angioplasty (PTCA) to treat stenotic coronary artery disease, there are relatively few prospective studies evaluating its long-term effectiveness. We prospectively randomized 212 stable patients with provocable myocardial ischemia and single-vessel subocclusive coronary disease to receive primary therapy with either PTCA or medical therapy. This report presents the clinical follow-up of these patients at a mean, after randomization, of 2.4 years for interview and 3.0 years for exercise testing. Of the 212 patients originally randomized, 175 received an extended follow-up interview, and 132 underwent exercise testing; 62% of patients in the PTCA group were angina free compared with 47% of patients in the medical group (p <0.05). Furthermore, exercise duration as measured by treadmill testing was prolonged by 1.33 minutes over baseline in the PTCA group, whereas it decreased by 0.28 minutes in the medical group (p <0.04). Although the angina-free time on the treadmill was not different (p=0.50), fewer patients in the medical group developed angina on the treadmill at 3 years than those in the PTCA group (p=0.04). By 36 months, excluding the initial randomized PTCA, use of PTCA and use of coronary artery bypass surgery were not different in the 2 treatment groups. These data indicate that some of the early benefits derived from PTCA in patients with single-vessel coronary artery disease are sustained, making it an attractive therapeutic option for these patients.

Inadequacy of the Gorlin formula for predicting prosthetic valve area.

A total of 135 patients with normally functioning prosthetic aortic valves who were catheterized 6 months after placement of Hancock, modified Hancock or Bjork-Shiley prostheses were studied to determine the magnitude of error in Gorlin formula estimates of prosthetic aortic valve area. All patients were male, selected from 13 participating hospitals and routinely followed after valve replacement for 5 years. Hemodynamically determined Gorlin valve areas were compared with independently verified actual valve areas. Actual Hancock areas were measured from videotapes of valves exercised in a pulse duplicator flow model. Actual Bjork-Shiley areas were calculated directly from the valves' inner ring radius. Gorlin valve areas correlated poorly with actual valve areas (r = 0.39). The mean Gorlin formula error was 0.36 cm2 (standard deviation = 0.32). Gorlin areas overestimated actual areas by greater than 0.25 cm2 in 43 patients (32%) and underestimated actual areas by greater than 0.25 cm2 in 29 (21%). It was concluded that the Gorlin formula inaccurately predicts prosthetic valve area in the aortic position. Overreliance on this formula in assessing aortic stenosis could lead to errant clinical decisions.

Echocardiography in acute and remote myocardial infarction.

Two dimensional echocardiography is just beginning to be used to characterize cardiac damage in patients with acute myocardial infarction. The two dimensional approach allows for a more comprehensive evaluation of cardiac anatomy and is able to detect with high sensitivity changes in regional wall motion that previously were sometimes missed or only found with difficulty using M mode echocardiography. Two dimensional echocardiography appears to offer a basis for quantifying the extent of myocardial damage in acute myocardial infarction and thus may permit objective assessment of therapeutic modalities and prognosis. In addition, the technique facilitates recognition of specific complications in acute myocardial infarction. In particular, the technique offers te ability to distinguish true from false ventricular aneurysm, postinfarction ventricular septal defect from papillary muscle dysfunction and rupture, and right ventricular infarction from cardiac tamponade.

Prognosis for aorta-coronary graft patency. A comparison of preoperative and intraoperative assessments.

For prognostication of aorta-coronary bypass graft patency, preoperative angiographic assessment of the recipient vessel and the regional left ventricle was compared with the intraoperative measurement of the internal diameter of the vessel and graft flow in 98 patients, in whom graft patency was evaluated at 1 year. Preoperative assessment of the recipient vessel did not correlate with the intraoperative measurement of the internal diameter or with the graft patency. Preoperative assessment of the regional left ventricular wall motion, on the other hand, was more valuable for prognosticating graft patency. Regions assessed as normal or hypokinetic had equally good graft patency, whereas akinetic or dyskinetic areas had only a 54% patency rate. Intraoperative measurement of the internal diameter of the vessel and graft flow were reliable predictors of graft patency: The larger the internal diameter and the greater the graft flow, the better the graft patency. Best surgical results can therefore be predicted when the internal diameter of the recipient vessel is 2.5 mm or more, graft flow is 100 ml/min or more, and the regional left ventricle moves well.

Platypnea syndrome after left pneumonectomy.

Contrast two-dimensional echocardiography (2DE) was used to demonstrate right-to-left shunting at the atrial level in a 49-year-old man with platypnea and orthostatic cyanosis which developed after a left pneumonectomy. This patient's systemic arterial saturation decreased with phlebotomy and increased with volume administration. This syndrome disappeared after repair of a previously unrecognized atrial septal defect. Right-to-left shunting in atrial septal defect is usually explained by a change in the relationship of right and left ventricular compliance with the right ventricle becoming less compliant (ie, stiffer) than the left. Pneumonectomy can affect atrial emptying either directly by mechanical means or indirectly by changing relationships in ventricular compliance. Contrast 2DE played key role in initially establishing the etiology of cyanosis in this complicated case.

Noninvasive tests to evaluate the severity of aortic stenosis. Limitations and reliability.

Fifty patients were examined with phonocardiograms, carotid pulse tracings, and M-mode echocardiograms to evaluate the ability of noninvasive tests to identify the severity of aortic valvular disease as determined at cardiac catheterization. Linear and multivariate analysis showed these noninvasive approaches to have only fair correlation with the severity of the disease. A binary division of the population under study into severe and nonsevere subgroups based on aortic valvular area (less than or equal to 0.8 sq cm in severe group [n = 25]; greater than 0.8 sq cm in nonsevere group [n = 25]) allowed sensitivity, specificity, and likelihood ratios to be determined. The likelihood ratio increased fourfold as the interval from the ECG Q wave to the murmur's peak (Q-MP) prolonged to 320 msec and increased sevenfold when the rate-corrected left ventricular ejection time (delta LVET) was more than 40 msec beyond values predicted from standard regression equations. Echocardiographic measurements were less helpful. Prolonged values of Q-MP and delta LVET proved to be the best discriminators of severe aortic valvular disease in this population where the prevalence of severe and nonsevere disease was equal.

Echocardiographic evaluation of left ventricular function.

The ability of echocardiography to assess left ventricular function is entering an era of transition. Most existing data have been derived from M-mode measurements made along a single echo beam axis and, as such, were based on the assumption that the performance of the sampled segment represented that of the whole ventricle. The recent availability of two dimenensional echocardiography lessens the need to rely on this assumption.

Is computer interpretation of the exercise electrocardiogram a reasonable surrogate for visual reading? Veterans Affairs ACME Investigators.

BACKGROUND: Interpretation of exercise tests as positive or negative is primarily based upon exercise-induced ST segment changes. Consistently accurate measurements are difficult to obtain during exercise. HYPOTHESIS: This study compared on-line computer-generated electrocardiographic (ECG) analysis with visual interpretation. The goals were to document the extent of agreement, establish reasons for disagreements, characterize ST-segment depression (extent, onset, duration), and determine the sensitivity and ability to localize coronary artery disease for each method. METHODS: Comparisons were made in 120 patients at eight Veterans Affairs Medical Centers. An exercise test was considered positive if > 1.0 mm horizontal or downsloping ST-segment depression was detected 0.08 s after the J point during exercise or recovery. The ST-segment depression had to be present on at least two successive ECG recordings 15 s apart. Computer interpretation was based on median averaged beats. RESULTS: There was an 88% agreement of visual and computer interpretations [106/120 (both positive, n = 62; both negative, n = 44)]. The disagreements involved visual negative, computer positive in 10 cases and visual positive, computer negative in 4 cases. Correlation was excellent between methods for characterization of ST-segment depression (p < 0.0001). Sensitivity for detecting and the ability to localize coronary artery disease (> or = 70% stenosis) were similar for both methods. CONCLUSION: This computer algorithm using median averaged beats is a reasonable surrogate for visual interpretation of the exercise ECG, making it a valuable source of confirmation of physician readings in large research trials and in clinical settings.

Approaches to determination of left ventricular volume and ejection fraction by real-time two-dimensional echocardiography.

Left ventricular volumes and ejection fraction were derived from real time two-dimensional echocardiographic images (2 DE) and single plane (RAO) left ventricular cineangiograms in a series of 50 patients. Prospective application of a series of 6 alternate algorithms showed that a modified Simpson's rule approach using mitral and papillary muscle cross sections and an apical four chamber view provided the best 2 DE - angiographic correlations: for end-diastolic volume r = 0.82, SEE = 39 ml; for end-systolic volume r = 0.90, SEE = 29 ml and for ejection fraction r = 0.80, SEE = 0.09. The large SEE for volume determination indicates that further refinements are necessary to predict left ventricular volumes adequately; however, ejection fraction can be derived with an accuracy which allows practical clinical decisions in patients with satisfactory 2 DE images.