Intravenous adenosine (adenoscan) versus exercise in the noninvasive assessment of coronary artery disease by SPECT.

Fifteen patients at a mean age of 58 underwent adenosine and maximal exercise thallium SPECT imaging. All scans were performed 1 week apart and within 4 weeks of cardiac catheterization. SPECT imaging was performed after the infusion of 140 micrograms/kg/min of adenosine for 6 minutes. Mean heart rate increment during adenosine administration was 67 +/- 3.7 to 77 +/- 4.1. Mean blood pressure was 136 +/- 7.2 to 135 +/- 6.2 systolic and 78 +/- 1.8 to 68 +/- 2.6 diastolic. No adverse hemodynamic effects were observed. There were no changes in PR or QRS in intervals. Five stress ECGs were ischemic. No ST changes were observed with adenosine. Although 68% of the patients had symptoms of flushing, light-headedness, and dizziness during adenosine infusion, symptoms resolved within 1 minute of dosage adjustment or termination of the infusion in all but one patient, who required theophylline. Sensitivity for coronary artery detection was 77% and specificity 100%. Concordance between adenoscans and exercise thallium scintigraphy was high (13/15 = 87%). In two patients, there were minor scintigraphic differences. The authors conclude that adenosine is a sensitive, specific, and safe alternative to exercise testing in patients referred for thallium imaging and may be preferable to dipyridamole.

Exercise first-pass radionuclide assessment of left and right ventricular function and valvular regurgitation in symptomatic mitral valve prolapse.

The changes in right ventricular (RV) and left ventricular (LV) function and in regurgitant fractions on first-pass exercise radionuclide angiography (RNA) were assessed in 29 consecutive patients with symptomatic mitral valve prolapse (MVP). The mean right ventricular ejection fraction (RVEF) was 35 +/- 8% at rest and 46 +/- 15% after exercise (p less than 0.001). The mean left ventricular ejection fraction (LVEF) was 62 +/- 11% at rest and 74 +/- 13% after exercise (p less than 0.001). Seven of 29 patients had an abnormal RV response and 6 had an abnormal LV response. Eight had abnormal wall motion after exercise. A total of 12/29 patients (41%) had one or more abnormalities. The mean left-sided regurgitant fraction before exercise was 27 +/- 17% in 21/29 patients (72%) and 31 +/- 21% after exercise (p = ns). An additional 5 patients (17%) developed left-sided regurgitation after exercise. These findings indicate that wall motion abnormalities and abnormal RVEF and LVEF responses to exercise occur in symptomatic MVP patients. In addition, 26/29 (89.6%) had left-sided regurgitation after exercise. Since the presence of a murmur did not correlate with the presence of mitral regurgitation by RNA, then symptomatic patients with MVP should have first-pass exercise RNA to assess the presence of regurgitation at rest and after exercise. Antibiotic prophylaxis is recommended in MVP patients with systolic murmurs or with regurgitation. Since patients without murmurs can have regurgitation, further study is necessary to determine the need for endocarditis prophylaxis in these patients.

Adjunct endarterectomy of the left anterior descending coronary artery.

During a three-year period, complete revascularization of diffusely diseased left anterior descending (LAD) coronary arteries was accomplished by extensive endarterectomy in conjunction with bypass grafting in 37 patients in whom conventional bypass was not feasible. This group constituted 7.0% of all patients undergoing nonemergency coronary revascularization during this period. The left internal mammary artery was used to bypass the endarterectomized LAD artery in 22 patients. There was 1 (2.7%) operative death and 1 perioperative myocardial infarction. At follow-up, which was 100% with a mean of 41.4 months, all endarterectomy patients were in New York Heart Association Functional Class I or II. Twenty-four endarterectomy patients underwent first-pass radionuclide angiographic stress testing 20 months after operation. Twenty patients (83%) had excellent postoperative exercise tolerance, achieving 5 to 7 mets on treadmill testing. Left ventricular functional reserve was preserved, as evidenced by an increase of global ejection fraction from 48 +/- 15% at rest to 59 +/- 18% (p less than 0.005) with exercise. A similar increase was measured in the proximal and distal anterior wall segmental ejection fractions. No difference in response to exercise was found between the internal mammary artery and the vein graft groups. Thus, complete revascularization of the diffusely diseased LAD artery can be accomplished by adjunct endarterectomy without added morbidity or mortality and with excellent functional results.

Long-term follow-up by exercise radionuclide angiography of patients after valve replacement for aortic regurgitation.

The long-term effects of valve replacement for chronic isolated aortic regurgitation as assessed by first-pass exercise radionuclide angiography have never been reported. We studied 20 males and 5 females before, 15 months postoperatively, and from 29 to 109 (mean 62 +/- 21) months following valve replacement with exercise radionuclide angiography. Mean peak heart rate did not change for the three studies. Peak systolic blood pressure decreased from 201 +/- 42 mmHg to 185 +/- 24 mmHg at 15 months and further declined to 177 +/- 32 mmHg by the long-term study (p less than 0.03). The mean resting left ventricular ejection fraction improved from 44 +/- 15% preoperatively to 57 +/- 18% at 15 months (p less than 0.002) with no further improvement by the long-term evaluation. The postexercise ejection fraction improved from 42 +/- 13% preoperatively to 61 +/- 21% at 15 months (p less than 0.002) also with no change by the long-term study. The duration of exercise improved from 9.7 +/- 4.6 min to 11.9 +/- 3.4 min (p less than 0.03) at 15 months with no additional improvement long term. Improvement in resting and postexercise ejection fraction and in exercise duration is maximal at 15 months. Accuracy and cost containment suggest that assessment of the maximal change in ejection fraction by exercise radionuclide angiography after aortic valve replacement in asymptomatic patients be limited to the 15-month interval.

Preliminary experience in the use of ultrafast computed tomography to diagnose aortic valve stenosis.

Eight patients, mean age 72 years, with aortic valve stenosis were studied by ultrafast CT 1 day after cardiac catheterization. After injection of radiographic contrast material through a peripheral vein, two contiguous eight-level R wave-triggered cine mode scans in the short axis were acquired, starting above the aortic valve and continuing through the apex of the left ventricle. Seven of eight patients, all with calcified aortic valves, had a detectable central orifice. Catheterization-derived aortic valve areas were within 0.25 cm2 of the CT valve areas in six of seven. LV mass was measured by ultrafast CT in the eight patients with aortic valve stenosis (121.6 +/- 18.2 gm/m2) and was found to be significantly higher (p less than 0.0001) than that in a group of eight subjects with normal LV function, no history of hypertension, and normal ECGs (73.0 +/- 13.1 gm/m2). It is concluded that in selected cases ultrafast CT can contribute to the assessment of severity of calcific aortic stenosis by measurement of LV mass and valve area.

Exercise radionuclide assessment of left ventricular function before and after coronary bypass surgery.

The effects of elective saphenous vein coronary artery bypass surgery on left ventricular ejection fraction were assessed by using exercise first-pass radionuclide angiography in 66 consecutive patients. All patients with left main coronary artery or concomitant valvular disease were eliminated from the study. Before surgery, 7 patients had normal postexercise left ventricular function (Group 1), 33 had normal resting left ventricular function with an abnormal response to exercise (Group 2), and 26 had an abnormal resting left ventricular ejection fraction with an abnormal response to exercise (Group 3). Following surgery, patients in all three groups had no change in mean resting left ventricular ejection fraction; however, patients in Groups 2 and 3 had significant improvement in mean postexercise left ventricular ejection fraction (p less than 0.0001 and p less than 0.0054 respectively), whereas patients in Group 1 did not. Previous studies reported improvement in postexercise ejection fraction in patients with reduced resting left ventricular function and with an ischemic response to exercise (Group 3). But this is the first study to confirm improvement in postexercise function in patients with normal resting function and an ischemic response to exercise (Group 2).

Rest-exercise radionuclide angiographic assessment of left ventricular function in chronic aortic regurgitation: significance of serial studies in medically versus surgically treated groups.

Forty consecutive asymptomatic patients with chronic aortic regurgitation who underwent three serial yearly rest and postexercise radionuclide angiograms were compared with 27 consecutive patients with chronic aortic regurgitation and aortic valve replacement who were studied preoperatively, 3 and 15 months postoperatively. Patients were divided into four subgroups based upon the resting left ventricular ejection fraction and the functional reserve on the initial study. Of the 40 medically treated patients, 19 (47.5%) and 24 (60%) demonstrated a response at least one type lower at 12 months and 24 months, respectively. Initial functional reserve, initial duration of exercise, and the change in exercise duration during the 24 months was not associated with changes in resting or postexercise left ventricular ejection fraction. A seesaw pattern was observed between the resting and the postexercise left ventricular ejection fraction as ventricular function deteriorated. We observed in the surgical groups a reversal of the seesaw interaction between the resting and postexercise ejection fraction seen in the medical patients. In the surgical groups the left ventricular end-diastolic pressure, initial functional reserve, initial duration of exercise, and change in exercise duration postoperatively were not predictors of improvement in left ventricular function at 15 months. Comparing medical and surgical serial data, we suggest yearly radionuclide angiographic determination of rest left ventricular ejection fraction in asymptomatic patients with chronic aortic regurgitation. When the rest ejection fraction is less than 50%, exercise angiography should be performed to determine functional reserve. When functional reserve is also abnormal, surgery should be recommended.

Left ventricular function after elective aneurysmectomy.

Employing rest and exercise first-pass radionuclide angiography before and 3 months after surgery, we studied patients with hemodynamically stable left ventricular aneurysm (LVA) undergoing both coronary artery bypass surgery to relieve angina pectoris and elective aneurysmectomy. There were 15 patients, 14 men and 1 woman with a mean age of 54 +/- 7 years. All patients had anterior and/or apical LVA. After surgery the postexercise mean left ventricular ejection fraction (LVEF) for the whole group improved significantly (p less than 0.004) compared with the preoperative value, but the resting LVEF did not change. The duration of exercise improved (p less than 0.01) after surgery, but not the double product. However, based upon the preoperative LVEF response to exercise, two groups were seen: Group A (n = 5) had greater than or equal to 5% increase in their LVEF with exercise versus Group B (n = 10), who had less than 5% increase or a decrease in their LVEF. Postoperatively, Group A decreased their LVEF with exercise and failed to improve exercise capacity or double product. Postoperatively, Group B increased the LVEF by greater than or equal to 5% as well as increasing exercise capacity (p less than 0.01), and double product (p less than 0.03). Group A had lower preoperative LVEF than Group B (p less than 0.01) and larger LVA. Patients with hemodynamically stable LVA who require coronary artery bypass surgery for angina should not have aneurysmectomy. The presence of hemodynamically stable LVA is not a contraindication to deriving benefit from myocardial revascularization.

Radionuclide angiography in the quantitation of mitral regurgitation.

First pass radionuclide angiography (RA) was used to assess its ability to detect and quantitate the presence of left-sided regurgitation due to isolated mitral regurgitation (MR). In this study the nuclear regurgitant fraction (NRF) obtained from first pass RA was correlated with the results of contrast ventriculography (CV) in 50 patients, 18 with and 32 without MR. The correlation between CV and RA in the confirmation and quantification of isolated MR revealed a sensitivity of 100 percent and a specificity of 97 percent in patients with LVEF greater than or equal to 35 percent.

Tricuspid regurgitation by radionuclide angiography and contrast right ventriculography: a preliminary observation.

In a retrospective study correlating the degree of tricuspid regurgitation seen on first-pass radionuclide angiography with that seen on contrast right ventriculography in 51 patients, ten had no tricuspid regurgitation by contrast ventriculography, whereas by radionuclide angiography nine had no regurgitation and one had minimal regurgitation. Of eight patients with minimal tricuspid regurgitation by contrast ventriculography, five had minimal regurgitation by nuclide angiography and three had no regurgitation. Of the 11 patients with mild to moderate tricuspid regurgitation by contrast studies, ten had mild to moderate regurgitation and one had severe regurgitation by nuclide angiography. Of 22 patients with moderate to severe tricuspid regurgitation by contrast studies, 15 had moderate to severe regurgitation and seven had mild to moderate regurgitation by nuclear angiography. In this preliminary study comparing radionuclide angiography with contrast right ventriculography, there were three false-negative and one false-positive nuclide angiograms, giving a sensitivity of 93% and a specificity of 90%.