Biomedical subjects

L Pace

Publications and source records attributed to L Pace.

At least 19 recordsLinked to original sources

PubMed1996

Effects of dual-chamber pacing in hypertrophic cardiomyopathy on left ventricular outflow tract obstruction and on diastolic function.

Hypertrophic cardiomyopathy (HC) is characterized by impaired diastolic function and, in about 1/4 of patients, left ventricular (LV) outflow tract obstruction. Atrioventricular (AV) pacing diminishes LV outflow tract gradient in HC, but impairs diastolic function in the experimental animal and in different categories of patients. To investigate the effects of AV pacing on hemodynamics and LV function in obstructive HC, 16 patients with HC were studied by cardiac catheterization and simultaneous radionuclide angiography during atrial and AV pacing. The resting LV outflow tract gradient decreased with AV pacing from 60 +/- 34 to 38 +/- 37 mm Hg (mean +/- SD; p <0.001). Regional ejection fraction decreased significantly at the septal level from 0.81 +/- 0.21% to 0.69 +/- 0.27% (p <0.01). Pulmonary artery wedge pressure increased from 10 +/- 5 to 15 +/- 6 mm Hg (p <0.001). AV pacing induced asynchrony (i.e., the coefficient of variation of the time to end-systole increased from 7 +/- 4% to 14 +/- 10% (p <0.01). The time constant of isovolumetric relaxation (t) increased from 58 +/- 24 to 74 +/- 33 ms (p <0.02), and peak filling rate decreased from 491 +/- 221 to 416 +/- 184 ml/s (p <0.05). Thus, AV pacing greatly diminishes resting obstruction through a reduction in septal ejection fraction (i.e., an increase in LV outflow tract width in systole), but impairs active diastolic function and increases filling pressures. These latter effects are potentially detrimental in patients with HC in whom diastolic dysfunction is present.

Adult↗

PubMed1995

Dobutamine echocardiography predicts improvement of hypoperfused dysfunctional myocardium after revascularization in patients with coronary artery disease.

BACKGROUND: In patients with coronary artery disease, dysfunctional hypoperfused myocardium at rest may represent either necrotic or viable hibernating myocardium. The accuracy of inotropic stimulation in identifying hypoperfused, reversibly dysfunctional myocardium has not been extensively investigated. METHODS AND RESULTS: Eighteen patients with stable chronic coronary artery disease underwent, while off drugs, quantitative 201Tl single-photon emission computed tomography after rest injection (2 to 3 mCi), two-dimensional echocardiography at rest and during dobutamine (5 to 10 micrograms/kg per minute i.v.), and radionuclide angiography. Single-photon emission computed tomography and echocardiography at rest were repeated 34 +/- 10 days after coronary revascularization, and radionuclide angiography was repeated 45 +/- 13 days after revascularization. Resting hypoperfusion was defined as 201Tl uptake < 80% of maximal activity. Systolic function was scored from 1 (normal) to 4 (dyskinesia), and functional improvement was defined as a score change > 1 grade. Of 79 dysfunctional hypoperfused segments, 48 (61%) improved function after revascularization. In 42 (88%) of these latter segments, function had improved during dobutamine. Conversely, systolic function after revascularization did not improve in 31 segments, and in 27 (87%), it had not improved during dobutamine. Functional improvement after revascularization was observed in 42 (91%) of 46 segments manifesting an improvement during dobutamine as opposed to 6 (18%) of 33 segments that did not improve during dobutamine. Resting 201Tl uptake (% of maximal activity) before revascularization (65 +/- 9%) significantly increased at follow-up in segments where function improved (70 +/- 12%, P < .005), whereas it did not change significantly in segments with unchanged systolic function after revascularization (from 57 +/- 13% to 60 +/- 17%, P = NS). In 10 patients with prerevascularization ejection fraction < 45%, left ventricular ejection fraction significantly increased from 36 +/- 7% before revascularization to 42 +/- 7% at follow-up (P < .05). CONCLUSIONS: Inotropic stimulation using dobutamine echocardiography identifies hypoperfused reversibly dysfunctional myocardium. Functional improvement during dobutamine is highly predictive of improvement after revascularization.

Aged↗

PubMed1995

Assessment of systolic wall thickening using technetium-99m methoxyisobutylisonitrile in patients with coronary artery disease: relation to thallium-201 scintigraphy with re-injection.

The results of resting planar ECG-gated technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) imaging were compared with those of thallium-201 (Tl) re-injection after exercise-redistribution scintigraphy in 20 patients (19 men, 1 woman, mean age 53 +/- 10 years) with angiographically proven coronary artery disease. Eight normal subjects (seven men, one woman, mean age 50 +/- 8 years) constituted the control group. In these subjects, only resting 99mTc-MIBI imaging was performed. The standardized percent count increase from end-diastole to end-systole was calculated as an index of wall thickening in 13 segments for each study. Regional wall thickening index (WTI) and 99mTc-MIBI uptake were significantly different (P < 0.05) among segments classified as normal, reversible defects, irreversible defects with increased tracer uptake after re-injection (Re+) or irreversible defects with unchanged tracer uptake after re-injection (Re-) on Tl imaging. Furthermore, WTI and 99mTc-MIBI uptake were significantly higher (P < 0.05) in Re- segments with moderate reduction of Tl uptake (> or = 50% of peak activity) than in Re- segments with severe reduction of Tl uptake (< 50% of peak activity). A significant relationship between WTI and the results of Tl scintigraphy was observed (rho = 0.71, P < 0.0001). The percentage of Re- segments with severe reduction of WTI was significantly higher compared to Re+ segments (64% vs 3%, P < 0.01). Furthermore, compared with moderate Re- segments, a significantly higher percentage of severe Re- segments showed a severe reduction of WTI (86% vs 48%, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Case-Control Studies↗

PubMed1995

Reverse redistribution in resting thallium-201 myocardial scintigraphy in chronic coronary artery disease: an index of myocardial viability.

UNLABELLED: The aim of this study was to evaluate whether segments with reverse redistribution on rest-redistribution 201Tl scintigraphy represent viable tissue or scar. METHODS: Nineteen patients (17 men, 2 women; mean age 53 +/- 8 yr) with coronary artery disease underwent rest-redistribution 201Tl study before coronary revascularization. Regional 201Tl uptake was analyzed quantitatively. Regional left ventricular wall motion was assessed before and after coronary revascularization using two-dimensional echocardiography and a three-point scale (1 = normal, 2 = hypokinetic, 3 = akinetic/dyskinetic). Two patterns of reverse redistribution were identified: pattern with normal 201Tl uptake in rest and abnormal in redistribution images and pattern with abnormal 201Tl uptake in rest and a significant decrease in redistribution images. RESULTS: Of the 247 segments analyzed, 85 were classified as normal, 37 as reversible defects, 83 as fixed defects and 42 as reverse redistribution (19 RR-A, 23 RR-B). Segments with RR-A differed from those with RR-B in wall motion score (1.4 +/- 0.7 versus 2.0 +/- 1.0). Electrocardiographic Q-waves were present in 26% of segments with RR-A and in 57% of segments with pattern B. After revascularization, all dyssynergic segments with pattern A showed improved wall motion, while only 40% of segments with pattern B and abnormal wall motion had such improvement. CONCLUSION: Our results suggest that dyssynergic segments with pattern A should be considered viable, while more caution should be used in classifying those with pattern B.

Coronary Angiography↗

PubMed1995

Effects of feeding fumonisin B1 in lactating sows and their suckling pigs.

The mycotoxin fumonisin B1 (FB1) produced by Fusarium moniliforme in corn causes pulmonary edema in finishing swine. Effects of lower nonlethal amounts and effects in lactating sows with suckling pigs are unknown. An initial study was conducted to determine a nonlethal concentration of FB1 for lactating sows; whether ingested FB1 could be detected in the milk; and whether toxicosis could be detected in the pigs, as determined by necropsy. Another study was conducted to determine toxicosis in the pigs by measuring liver sphinganine-to-sphingosine ratio, and whether ingested FB1 affected T-lymphocyte function in sows and their pigs. Furthermore, sows of this study were maintained in controlled hot (27 to 32 C, 50 to 70% relative humidity) and thermoneutral (21 C, 55% relative humidity) environments to determine whether high temperature exacerbated the effects of FB1. In the first study, 100 micrograms of FB1/g of corn soybean meal diet was found to be nonlethal when fed for 14 days. Fumonisin B1 was not detected in the milk at 30 ppb and lesions were not found in the necropsied pigs, including 1 from a sow that died of porcine pulmonary edema syndrome after ingesting FB1 at a concentration of 175 ppm. In the second study, differences in liver sphinganine-to-sphingosine ratio of pigs were not found. Expressions of cell surface antigens on blood lymphocytes and lymphocyte proliferation response to various mitogens were not affected by FB1 or high temperature in sows or their pigs.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

[Morpho-functional diagnostic imaging in the assessment of viable myocardium in patients with ischemic heart disease. Correlations between myocardial perfusion and regional function of the left ventricle].

Forty patients (38 men and 2 women, mean age 56 +/- 9 years) with angiographic evidence of coronary artery disease underwent 201Thallium myocardial scintigraphy and two-dimensional echocardiography. 201Thallium uptake and echocardiographic regional ventricular function were studied in corresponding myocardial segments. On exercise-redistribution 201Thallium imaging, 308 segments (51% of the total) had normal Thallium uptake, 48 (8%) exhibited reversible defects and 244 (41%) irreversible defects. Of the latter 244 segments with irreversible defects, 114 (47%) exhibited increased tracer uptake (Re+) and 130 (53%) remained unchanged (Re-) after 201Thallium reinjection at rest. Regional ventricular function was significantly better in the segments with normal Thallium uptake than in the segments with reversible or irreversible defects (p < 0.001). Furthermore, the segments with irreversible defects Re- had impaired regional function compared to the segments with irreversible defects Re+ (p < 0.001). Coronary artery stenosis was significantly more severe in the segments with irreversible defects Re- (93 +/- 16%) than in those with reversible defects (81 +/- 20%) and with irreversible Re+ defects (80 +/- 20%) (both p < 0.001). In conclusion, in coronary artery disease patients, exercise-redistribution 201Thallium cardiac imaging with reinjection at rest can identify severely ischemic but still viable myocardium and may be particularly useful in the prognosis of such patients.

Adult↗

PubMed1995

Ambulatory monitoring of left ventricular function during cardiopulmonary exercise tests in normal sedentary subjects.

UNLABELLED: Ambulatory monitoring (VEST) of left ventricular (LV) function is a useful and accurate method to measure cardiac function during exercise and rest. The aim of this study was to evaluate LV response to exercise in normal sedentary subjects. METHODS: Ten normal sedentary subjects underwent continuous ambulatory monitoring of LV function by VEST during upright bicycle exercise associated with combined analysis of pulmonary gas exchange. All parameters of LV function were measured in control conditions at rest, at the anaerobic threshold (point of nonlinear increase in ventilation relative to oxygen uptake) and at peak oxygen uptake (peak VO2). RESULTS: Heart rate and cardiac output significantly increased from control conditions to anaerobic threshold (p < 0.001) and from anaerobic threshold to peak VO2 (p < 0.001). Ejection fraction, end diastolic volume and stroke volume significantly increased from control conditions to anaerobic threshold (p < 0.001), showing no significant change from anaerobic threshold to peak VO2. Finally, end-systolic volume significantly decreased from control conditions to anaerobic threshold (p < 0.001), showing no significant change from anaerobic threshold to peak VO2. CONCLUSION: VEST is particularly useful in the evaluation of cardiac response to exercise in normal sedentary subjects, providing a better understanding of the spectrum of the normal LVEF response to exercise. Our data demonstrate that ejection fraction response to exercise is variable after anaerobic threshold, and a uniform increase is not necessarily expected in normal sedentary subjects.

Adult↗

PubMed1995

Impaired left ventricular diastolic filling in patients with acromegaly: assessment with radionuclide angiography.

UNLABELLED: Acromegaly is associated with increased cardiac morbidity and mortality, but it is not clear whether this is the result of a specific disease of heart muscle or of increased incidence of hypertension. METHODS: Twenty-six patients with acromegaly (11 male and 15 female, mean age 45 +/- 13 yr) and 15 and 12 age- and sex-matched normal controls underwent high temporal resolution radionuclide angiography and two-dimensional echocardiography at rest. RESULTS: Normal controls and patients with acromegaly did not differ with respect to heart rate, ejection fraction, time to end systole, peak ejection rate (PER) and time to PER. In contrast, peak filling rate (PFR), normalized to end diastolic volume (EDV), or stroke volume (SV), or expressed as the ratio of PFR-to-PER was reduced (p < 0.01), time to PFR (TPFR) was prolonged (p < 0.01), and echocardiographic left ventricular mass index was higher (p < 0.001) in patients with acromegaly compared to normals. Patients with acromegaly were divided in normotensives (group 1, n = 17) and hypertensives (group 2, n = 9). Although left ventricular mass index was significantly (p < 0.01) higher in group 2 compared to group 1, PFR and time to PFR were not different between the two groups of acromegalic patients. In the entire group of patients with acromegaly significant relationships between left ventricular mass index and EDV/s (r = -0.56, p < 0.01), SV/s (r = -0.73, p < 0.001), and PFR/PER (r = -0.61, p < 0.001) were observed. CONCLUSION: Patients with acromegaly have impaired left ventricular diastolic filling at rest related to greater left ventricular mass index even in the absence of systemic hypertension.

Acromegaly↗

PubMed1995

Aurintricarboxylic acid reduces platelet deposition in stenosed and endothelially injured rabbit carotid arteries more effectively than other antiplatelet interventions.

In the present study we tested the effects of different antithrombotic interventions on platelet deposition in experimentally-stenotic rabbit carotid arteries with endothelial injury. Platelet deposition, quantitated by labeling autologous platelets with 111In-oxine, was significantly reduced compared to control animals by all interventions tested, i.e., R 68070, a drug with thromboxane A2 synthase and receptor blocking properties, BN 52021, a PAF receptor antagonist, aurintricarboxylic acid (ATA), an inhibitor of platelet glycoprotein (Gp) Ib/von Willebrand factor (vWf) interaction, AZ-1, a monoclonal antibody against rabbit GP IIb/IIIa, the platelet receptor for fibrinogen, and AP-1, a monoclonal antibody against rabbit tissue factor. ATA was significantly more effective than all the other interventions in reducing platelet deposition in the stenotic vessels. We conclude that inhibition of Gp Ib/vWf interaction may be a more suitable target for antithrombotic therapy under conditions of high shear stress, like those produced in this model.

Analysis of Variance↗

PubMed1994

Ambulatory monitoring of left ventricular function in patients with Parkinson's disease and postural hypotension.

Left ventricular (LV) function was continuously monitored using a radionuclide detector (VEST) after intravenous injection of 25 mCi technetium-99m labelled red blood cells in nine patients with Parkinson's disease and postural hypotension (group 1) and ten patients with Parkinson's disease but without postural hypotension (group 2). LV function and blood pressure were monitored in the supine position for 15 min (period A), upon changing posture from the supine to the upright position for 10 min (period B), and upon returning to the supine position for 10 min (period C). In group 1, the passage from period A to period B induced a significant decrease in end-diastolic volume, end-systolic volume and ejection fraction (all P < 0.01). In group 2, ejection fraction increased (P < 0.05) upon changing posture from the supine to the upright position. Ejection fraction (F = 33, P < 0.01), end-diastolic volume (F = 9, P < 0.05) and end-systolic volume (F = 10, P < 0.05) were significantly different between the two groups. In group 1, stroke volume, cardiac output and vascular peripheral resistance decreased from period A to period B (all P < 0.001). In group 2, no changes in stroke volume, cardiac output and vascular peripheral resistance were observed from period A to period B. All parameters were similar in the two groups during the periods A and C. Upon changing posture from the supine to the upright position, patients with Parkinson's disease and postural hypotension showed marked changes in parameters of LV function induced by vascular abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrocardiography, Ambulatory↗

PubMed1994

Technetium-99m methoxy isobutyl isonitrile simultaneous evaluation of ventricular function and myocardial perfusion in patients with congenital heart disease.

The authors evaluated the clinical applications of Tc-99m methoxy isobutyl isonitrile (MIBI) in the simultaneous assessment of ventricular function and myocardial perfusion in patients with congenital heart disease. Global ventricular function was assessed by first-pass ECG gated study. Myocardial perfusion was evaluated on images performed 1 hour after the injection of the tracer. Regional wall motion and systolic thickening were assessed by gated study acquired after the perfusion study. Two young patients were studied after a surgical Glenn procedure. The first patient, with a history of transposition of the great vessels and univentricular heart, had an ejection fraction of 44%. The left ventricle was dilated and the right ventricle was not appreciable. The septal and inferoapical regions showed reduced perfusion and reduced systolic thickening. The second patient, with a history of pulmonary atresia, septal defect and left ventricular hypoplasia, had a right ventricular ejection fraction of 37%. Regional wall motion, systolic thickening, and myocardial perfusion were normal. The right ventricle was hypertrophic and larger than the left ventricle. Thus, a single injection of Tc-99m MIBI allows noninvasive simultaneous assessment of global and regional ventricular function and myocardial perfusion in young patients with complicated congenital heart disease.

Child, Preschool↗

PubMed1994

Reverse redistribution in Tl-201 stress-redistribution myocardial scintigraphy. Effect of rest reinjection.

To clarify the clinical significance of Tl-201 reverse redistribution (RR), 33 patients with chronic coronary artery disease (CAD) underwent stress-redistribution Tl-201 cardiac imaging with rest reinjection, coronary arteriography, and 2D-echocardiography. Rest Tc-99m MIBI scintigraphy was also performed in 27 of the 33 patients. A total of 495 segments were analyzed for Tl-201 scintigraphy (405 for Tc-99m MIBI). Each segment was assigned to one of the major coronary artery territories. Two patterns of RR were identified; 1) pattern A (RR-A) showed normal Tl-201 uptake on stress images and lower than normal on redistribution images, and 2) pattern B (RR-B) showed lower than normal Tl-201 uptake on stress images with further decrease on redistribution images. The RR phenomenon was found in 46 (9% of the total) segments; 25 with RR-A and 21 with RR-B. Reverse redistribution pattern A segments had lower Tc-99m MIBI uptake (84 +/- 9% versus 92 +/- 10%, P < 0.0001) and a higher percentage of stenosed coronary arteries (80% versus 49%, P < 0.05) compared to normal segments (n = 204, 41% of the total). No difference in wall motion was observed between RR-A and normal segments. Of the 25 segments with RR-A, 14 showed enhanced Tl-201 uptake after reinjection (Re+) and 11 remained unchanged after reinjection (Re-). Segments that were Re- showed significantly (P < 0.05) lower Tc-99m MIBI uptake (79 +/- 9%) compared to Re+ segments (87 +/- 8%) and normal segments (92 +/- 10%).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Catheterization↗

PubMed1994

[Coronary angioplasty for the recovery of myocardial function after acute myocardial infarction: mid- and long-term results].

Sixty-three patients with previous myocardial infarction and documented hypoperfused reversibly dysfunctional myocardium after 201thallium tomography and/or echo-dobutamine were candidates to coronary angioplasty. Patients were enrolled at four hospitals (Naples, Milan, Pisa and Varese) and evaluated by different study protocols, while endpoint (presence of myocardial viability and efficacy of coronary angioplasty to improve dysfunctional myocardium) was similar. Sixty-two patients underwent successful angioplasty, and early evaluation (between 1 and 3 months after procedure) showed the ability of either 201thallium tomography and/or dobutamine echocardiography, to identify hypoperfused reversibly dysfunctional myocardium. Ten patients underwent late (after 8 +/- 2 months) evaluation of both wall motion and myocardial perfusion showing a sustained improvement in 25/32 hypoakinetic myocardial segments. Our data confirm the efficacy of revascularization of hypoperfused dysfunctional myocardial segments by coronary angioplasty. Further studies are warranted to obtain a better patient stratification and to evaluate the long-term results.

Adult↗

PubMed1994

Evaluation of left ventricular asynchrony by radionuclide angiography: comparison of phase and sector analysis.

UNLABELLED: The aim of this study was to assess the optimal method to evaluate asynchrony in equilibrium radionuclide angiography (RNA). METHODS: We studied 20 patients (14 males and 6 females, age range 25-60 yr) with RNA during atrial and sequential atrioventricular (AV) pacing, which increased left ventricular (LV) asynchrony. Both studies were performed at the same heart rate. Asynchrony was assessed either on phase images, by computing the standard deviation of the phase distribution (SD-P) and by sector analysis. Systolic and diastolic asynchrony were evaluated as the coefficient of variation of time to end systole (CV-TES) and time to peak filling rate (CV-TPFR) in four sectors. In addition, phase values were computed on time-activity curves from the same sectors, and their standard deviation (SD-Psec) was computed. RESULTS: During atrial pacing SD-P was 32.3 degrees +/- 6.7 degrees and did not change during AV pacing (32.1 degrees +/- 5.6 degrees, p = n.s.). Both CV-TES and CV-TPFR had a significant increase during AV pacing (from 7.7% +/- 3.9% to 11.5% +/- 6.4%, p < 0.01, and from 8.4 degrees +/- 5.8 degrees to 12.9 degrees +/- 6.7 degrees, p < 0.001). AV pacing led to a significant increase in SD-Psec (from 6.3 degrees +/- 4.0 degrees to 12.6 degrees +/- 9.7 degrees, p < 0.05). Moreover, reproducibility was assessed in 15 additional age-matched patients. The results of the reproducibility study indicate a better repeatability for CV-TES and CV-TPFR. CONCLUSIONS: The findings of this study suggest that sector analysis with calculation of indices of LV systolic and diastolic asynchrony is better suited for quantitation of LV temporal nonuniformity.

Cardiac Catheterization↗

PubMed1994

Adenosine technetium-99m-methoxy isobutyl isonitrile myocardial tomography in patients with coronary artery disease: comparison with exercise.

UNLABELLED: We compared the results of adenosine and bicycle exercise 99mTc-methoxy isobutyl isonitrile (MIBI) myocardial SPECT in 22 patients (18 males and 4 females, mean age 51 +/- 11 yr) with angiographically documented coronary artery disease (CAD). METHODS: All patients were submitted on separate days to three intravenous injections of 99mTc-MIBI (20 mCi); one at rest, one during exercise and one during adenosine (140 micrograms/kg per min for 6 min with injection of 99mTc-MIBI at 4 min). A total of 484 myocardial segments were quantitatively analyzed. RESULTS: Adenosine induced a significant increase of heart rate (94 +/- 16 bpm at peak versus 70 +/- 13 bpm at rest, p < 0.01). Systolic and diastolic blood pressure were not significantly different after adenosine infusion compared to rest. In all segments, a significant relationship between exercise and adenosine 99mTc-MIBI uptake was observed (r = 0.90, p < 0.0001). Concordance between the two studies for identification of perfusion status was observed in 438 (90%) of the 484 segments (kappa value of 0.81). Agreement on localization of the perfusion defect to a specific vascular territory was 92%. CONCLUSION: Despite different hemodynamic effects, adenosine and exercise 99mTc-MIBI SPECT imaging provide similar information in the diagnosis and localization of CAD.

Adenosine↗

PubMed1994

Enhanced thallium-201 uptake after reinjection: relation to regional ventricular function, myocardial perfusion and coronary anatomy.

The aim of this study was to clarify the significance of enhanced thallium-201 (201Tl) uptake after reinjection following 4-hour redistribution imaging. Thirty-four patients with coronary artery disease (CAD) and left ventricular (LV) dysfunction (ejection fraction 32 +/- 10%) underwent exercise-redistribution (ER) 201Tl scintigraphy with rest injection, resting technetium-99m methoxy isobutyl isonitrile (MIBI) imaging, 2D-echocardiography, and coronary angiography. Wall motion (WM) was graded on echocardiographic images. A total of 510 myocardial segments were quantitatively analyzed. A total of 267 (52%) segments had normal (N) 201Tl uptake, 53 (10%) reversible (RD), and 190 (37%) irreversible (ID) 201Tl defects on ER images. Of these 190 ID, 84 (44%) showed enhanced 201Tl uptake after reinjection (Re+) and 106 (56%) remained unchanged after reinjection (Re-). MIBI uptake was significantly higher in RD compared to Re+ and Re- (both p < 0.01), and in Re+ compared to Re- (p < 0.01). The WM score was significantly lower in RD and Re+ compared to Re- (p < 0.01), while no difference was observed between RD and Re+. The severity of coronary artery stenosis was significantly lower in RD compared to Re+ and Re- (both p < 0.01), but no difference was observed between Re+ and Re-. The occurrence of collaterals was significantly higher (p < 0.01) in Re+ (69%) compared to Re- (38%). In conclusion, in patients with CAD and impaired LV function, enhanced 201Tl uptake after reinjection in myocardial segments with ID on ER images was associated with less severe WM abnormalities, higher MIBI uptake and the presence of collaterals.(ABSTRACT TRUNCATED AT 250 WORDS)

Collateral Circulation↗

PubMed1993

Resting technetium-99m methoxyisobutylisonitrile cardiac imaging in chronic coronary artery disease: comparison with rest-redistribution thallium-201 scintigraphy.

We studied 19 patients with angiographically proven coronary artery disease and left ventricular dysfunction (ejection fraction 33% +/- 8%) by resting technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) and rest-redistribution thallium-201 cardiac imaging. Thallium and 99mTc-MIBI studies were visually analysed. Of 285 segments, 203 (71%) had normal thallium uptake, 48 (17%) showed reversible thallium defects and 34 (12%) showed irreversible thallium defects. Of these 34 irreversible thallium defects, 19 (56%) were moderate and 15 (44%) were severe. Of the corresponding 285 segments, 200 (70%) had normal 99mTc-MIBI uptake, while 37 (13%) showed moderate and 48 (17%) showed severe reduction of 99mTc-MIBI uptake. Myocardial segmental agreement for regional uptake score between initial thallium and resting 99mTc-MIBI images was 90% (kappa = 0.78). Segmental agreement between delayed thallium and resting 99mTc-MIBI images was 77% (kappa = 0.44). In particular, in 26 (9%) segments 99mTc-MIBI uptake was severely reduced while delayed thallium uptake was normal or only moderately reduced. These data suggest that although rest-redistribution thallium and resting 99mTc-MIBI cardiac imaging provide concordant results in the majority of myocardial segments, some segments with severely reduced resting 99mTc-MIBI uptake may contain viable but hypoperfused myocardium. Thus, conclusions on myocardial viability based on 99mTc-MIBI uptake should be made with caution in chronic coronary artery disease.

Adult↗

PubMed1993

Rest-injected thallium-201 redistribution and resting technetium-99m methoxyisobutylisonitrile uptake in coronary artery disease: relation to the severity of coronary artery stenosis.

To compare rest-injected thallium-201 (Tl) redistribution and resting technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) myocardial uptake in chronic coronary artery disease (CAD), 15 patients with angiographically proven CAD and left ventricular (LV) dysfunction (ejection fraction 34% +/- 9%) were studied. All patients underwent rest-redistribution Tl and resting 99mTc-MIBI cardiac imaging. Gated 99mTc-MIBI images were also acquired to assess regional LV wall motion (WM). Myocardial segments (n = 225) were divided into three groups on the basis of the degree of coronary artery stenosis: group 1 (total occlusion, n = 82), group 2 (50%-99% of stenosis, n = 84) and group 3 (< 50% of stenosis, n = 59). WM was significantly worse in groups 1 and 2 compared to group 3 (P < 0.001), but no difference was observed between groups 1 and 2. Tl and 99mTc-MIBI uptake were significantly lower in groups 1 and 2 compared to group 3 (P < 0.001), and in group 1 compared to group 2 (P < 0.001). When Tl and 99mTc-MIBI uptake were directly compared. Tl uptake was higher than 99mTc-MIBI uptake in group 1 (P < 0.001), while no significant difference was observed in groups 2 and 3. Thus, both rest-injected Tl redistribution and resting 99mTc-MIBI uptake reflected the severity of coronary artery stenosis in CAD. However, in myocardial segments with total coronary occlusion Tl uptake was significantly higher than 99mTc-MIBI uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗