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Biomedical subjects

G M El-Said

Publications and source records attributed to G M El-Said.

8 recordsLinked to original sources
PubMed1997

Comparison of dobutamine stress echocardiography and 99m-technetium sestamibi SPECT myocardial perfusion scintigraphy for predicting extent of coronary artery disease in patients with healed myocardial infarction.

This study compares the value of dobutamine stress echocardiography and 99m-technetium methoxyisobutyl-isonitrile (MIBI) single-photon emission computed tomography (SPECT) in the assessment of extent and location of coronary narrowing in patients with healed myocardial infarction. Dobutamine (up to 40 microg/kg/ min)-atropine (up to 1 mg) stress echocardiography (DSE) in conjunction with MIBI SPECT was performed in 72 patients (52 men, mean age 57 +/- 11 years) with healed myocardial infarction referred for evaluation of myocardial ischemia. Ischemia was defined as new or worsened wall motion abnormalities at DSE and reversible perfusion defects at MIBI SPECT. Significant stenosis (> or = 50% luminal diameter stenosis) of the infarct-related artery was detected in 45 patients and of other coronary arteries in 22 patients. Sensitivity and specificity of remote ischemia for diagnosis of remote coronary stenosis were 68% (95% confidence interval [CI] 57 to 80) and 93% (CI 86 to 99) for DSE, and 64% (CI 52 to 76), and 90% (CI 83 to 98) for MIBI SPECT, respectively. The positive predictive value and specificity of peri-infarction ischemia for the diagnosis of infarct-related artery stenosis were 89% (CI 81 to 97) and 82% (CI 73 to 92) for DSE, and 87% (CI 79 to 95) and 82% (CI 73 to 92) for SPECT, respectively. The agreement between both techniques was higher for the diagnosis of remote than peri-infarction ischemia (84% vs 66%, p = 0.02). It is concluded that in patients with myocardial infarction undergoing dobutamine stress testing, both echocardiography and MIBI SPECT are clinically useful methods for the diagnosis of remote and infarct-related coronary artery stenosis.

Aged↗
PubMed1996

Relation between contractile response of akinetic segments during dobutamine stress echocardiography and myocardial ischemia assessed by simultaneous thallium-201 single-photon emission computed tomography.

There are no standard criteria for the diagnosis of myocardial ischemia in akinetic segments during dobutamine stress echocardiography (DSE). The aim of the study was to assess the relation between different responses of akinetic segments during DSE and ischemia assessed by thallium-201 single-photon emission computed tomography (SPECT). Dobutamine-atropine stress echocardiography with simultaneous stress-reinjection thallium-201 SPECT was performed in 67 patients with old myocardial infarction significant and coronary artery stenosis. Fourteen myocardial segments were matched for both DSE and SPECT. Ischemia on SPECT was defined as reversible thallium defects. In 257 akinetic segments, 4 patterns during DSE were identified: (1) biphasic response in 41 segments (16%), defined as improvement at low dose (5 to 10 microgram/kg/min) followed by worsening at high dose; (2) persistent akinesia in 155 segments (60%); (3) akinesia becoming dyskinesia in 39 segments (15%); and (4) sustained improvement in 22 segments (9%). Reversible thallium defects were detected in 21 segments (51%) in group 1, in 20 segments (13%) in group 2, none in group 3, and in 2 segments in group 4 (9%). The prevalence of reversible defects in biphasic segments was higher compared with other patterns (p <0.00001 vs groups 2 and 3, p <0.005 vs group 4). The ischemic perfusion defect score was significantly higher in group 1 than group 2. The positive predictive value of biphasic response for reversible thallium defects was similar to that of stress-induced dyssynergia in normal segments at rest (51% vs 58%). It is concluded that of the various responses of akinetic segments to dobutamine infusion, the biphasic response is associated with the highest prevalence and greatest severity of ischemic on thallium SPECT. Observation of contractile response at both low- and high-dose DSE is a valuable approach for the diagnosis of myocardial ischemia in akinetic segments.

Aged↗
PubMed1996

Low-dose dobutamine echocardiography and rest-redistribution thallium-201 tomography in the assessment of spontaneous recovery of left ventricular function after recent myocardial infarction.

Spontaneous improvement of contraction and perfusion occurs after acute myocardial infarction. The relative merit of low-dose dobutamine stress echocardiography (LDDE) and rest-redistribution thallium scintigraphy (RR TI) in this setting has not been evaluated. We studied 30 patients at 7 +/- 3 days after acute myocardial infarction with LDDE (5 to 10 micrograms/kg/min) and RR TI single photon emission computed tomography. Viability was defined as improvement of wall thickening at LDDE in the presence of redistribution or a defect with uptake > or = 50% of peak activity at RR TI. Baseline echocardiography and RR TI were repeated after 3 months. In 112 dyssynergic segments, viability was detected in 60 (54%) by RR TI and in 39 (35%) by LDDE (p < 0.005). Spontaneous improvement of function was detected in 35 (31 %) segments. In the same regions, thallium uptake increased significantly. The sensitivity, specificity, and accuracy of LDDE for predicting late improvement of wall motion were 77%, 84%, and 82%, respectively. Those of RR TI were 77%, 57%, and 63%, respectively. Specificity and accuracy of LDDE were higher than RR TI (p < 0.005). We conclude that a myocardial viability pattern after acute myocardial infarction is more frequently detected by RR TI than by LDDE. Both techniques are equally sensitive, but LDDE is a more specific predictor of spontaneous recovery of regional left ventricular function.

Adrenergic beta-Agonists↗
PubMed1976

Significance of pacemaker recovery time after the Mustard operation for transposition of the great arteries.

Pacemaker recovery time corrected for cycle length was measured in 24 patients 6 months to 3 years after the Mustard operation for transposition of the great arteries. This index of sinoatrial (S-A) nodal function was obtained by subtracting the control R-R interval from the first R-R interval recorded after 3 minutes of rapid atrial pacing at the superior vena caval-right atrial junction. Recovery times were compared with those of a control group of 54 children with various forms of congenital heart disease who had not had cardiac surgery and whose electrocardiogram revealed normal sinus rhythm. The longest corrected pacemaker recovery time in the control group was 250 msec. Recovery time was normal (mean 115 msec) in 13 of the 24 patients who had undergone the Mustard procedure and prolonged (mean 472 msec) in the other 11. In 4 of these 11 a junctional escape complex was recorded before recovery of the S-A node. The configuration of the P wave and the development of dysrhythmias in the postoperative follow-up period were compared in patients with a normal and a prolonged corrected pacemaker recovery time. The incidence of dysrhythmias was much smaller in the former group. Normal sinus rhythm after the first postoperative week was noted in 10 (76 percent) of patients with a normal corrected pacemaker recovery time but in only 2 (18 percent) of those with an abnormal recovery time. One patient with an abnormal recovery time died suddenly 26 months after operation in spite of good hemodynamic repair. A prolonged pacemaker recovery time after the Mustard operation for transposition of the great arteries indicated that rhythm abnormalities were likely to develop, but a normal recovery time did not exclude abnormal sinus nodal function.

Adolescent↗
PubMed1976

Protection of the sinus node in Mustard's operation.

The occurrence of dysrhythmias after the Mustard operation for transposition of the great arteries was compared in 70 patients operated upon before and 58 patients operated upon after January 1972 when surgical modifications aimed at preserving the sino-atrial node and its arterial supply were initiated. The surgical modifications included changing the site of the superior vena cava (SVC) cannulation away from the SVC-right atrial junction, incision into the right atrial wall anterior to the sulcus terminalis, and sewing of the superior part of the baffle patch away from the sino-atrial node area. A significant decrease in the incidence of dysrhythmias occurred in the group of patients operated upon after the surgical modifications. The modifications in surgical technique have reduced but not avoided dysrhythmias.

Arrhythmia, Sinus↗
PubMed1975

Hemodynamic and angiographic changes after Mustard operation for transposition of the great arteries.

After Mustard operation for transposition of the great arteries, hemodynamic and angiocardiographic changes were evaluated in 25 patients. In 19 patients, postoperative studies were done electively and, in 6 patients, they were required to investigate symptoms of heart failure, these symptoms were temporary in 4 patients and progressive in 2. Both of the latter had pulmonary venous obstruction which was later relieved successfully by reoperation. After operation, systemic arterial oxygen saturation and blood pressure increased and polycythemia disappeared in every patient. However, several complications-some of them unsuspected clinically-were identified by cardiac catheterization: (a) patch detachment in 5 patients; (b) obstruction of superior vena caval return in 10 patients; (c) obstruction of inferior vena return in 1 patient; and (d) pulmonary venous obstruction in 2 patients. The incidence of pulmonary or systemic venous obstruction was higher in patients who had a Dacron intraatrial baffle (8 of 19 patients). Comparison of 21 sets of preoperative and postoperative right ventricular angiograms demonstrated an increase in right ventricular trabeculations in each patient, poorer right ventricular contractility in 12 patients, and development of tricuspid insufficiency in nine patients. None of the patients with poor right ventricular contractility had had surgical ventriculotomy. Although Mustard operation for transposition of the great arteries is effective in relieving cyanosis, it may be followed by obstruction to systemic or pulmonary venous return, intraatrial patch detachment, tricuspid insufficiency and angiocardiographic evidences of poor right ventricular contractility.

Adolescent↗