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Biomedical subjects

M S Verani

Publications and source records attributed to M S Verani.

At least 55 records · Page 3Linked to original sources
PubMed1995

Role of adenosine thallium-201 tomography for defining long-term risk in patients after acute myocardial infarction.

OBJECTIVES: This study prospectively evaluated whether early assessment with adenosine thallium-201 tomography could better refine risk stratification on the basis of absolute extent of myocardial ischemia in postinfarction patients in clinically stable condition. BACKGROUND: Postinfarction patients are at increased risk for subsequent cardiac events. However, identifying high risk patients among those with residual myocardial ischemia is suboptimal. METHODS: All 146 patients enrolled underwent assessment of left ventricular function and had adenosine tomography performed early (mean [+/- SD] 5 +/- 3 days) after infarction. Excluded from analysis were 51 patients with revascularization after scintigraphy and 3 lost to follow-up. Statistical risk models were therefore generated from the remaining 92 patients. RESULTS: Cardiac events occurred in 30 (33%) of 92 patients over 15.7 +/- 4.9 months. Univariate predictors of all events were quantified perfusion defect size (p < 0.0001), absolute extent of left ventricular ischemia (p < 0.000001) and ejection fraction (p < 0.0001). Risk was best predicted by Cox analysis on the basis of 1) absolute extent of ischemia and ejection fraction (chi-square 24.6); 2) percent infarct zone ischemia and ejection fraction (chi-square 24.4); or 3) total perfusion defect size and percent infarct zone ischemia (chi-square 18.9). The variables that predicted all cardiac events were equally powerful at predicting only death and nonfatal reinfarction. Death was best predicted by total perfusion defect size. CONCLUSIONS: Risk analysis of individual patients early after infarction is feasible on the basis of the quantified extent of scintigraphic ischemia and severity of left ventricular dysfunction.

Adenosine↗
PubMed1995

Simultaneous assessment of myocardial perfusion and left ventricular function during transient coronary occlusion.

OBJECTIVES: We used technetium-99m sestamibi imaging to evaluate the magnitude of changes in left ventricular function and perfusion and to investigate their interdependence during transient coronary occlusion. BACKGROUND: Transient coronary occlusion during coronary angioplasty provides a unique opportunity for examining the effects of acute myocardial ischemia on left ventricular function and perfusion. METHODS: Thirty-five patients with normal left ventricular function underwent first-pass radionuclide angiography with technetium-99m sestamibi using a multicrystal gamma camera during balloon occlusion of a coronary artery. Single-photon tomography was performed 2.1 +/- 1.7 h later. Subsequently, all scans were repeated at rest. RESULTS: The mean size +/- SD of the perfusion defect during coronary occlusion was 23 +/- 18%, with significantly larger defects observed for occlusions of the left anterior descending coronary artery (39 +/- 20%) than for occlusions of the left circumflex (15 +/- 11%) or right (15 +/- 9%) coronary artery (p < 0.05). The mean change in ejection fraction from recovery to occlusion was -17 +/- 17% and was significantly larger for left anterior descending (-26 +/- 21%) and left circumflex (-15 +/- 11%) than for right (-8 +/- 10%) coronary artery occlusions (p < 0.05). For the entire group, ejection fraction during occlusion correlated significantly with perfusion defect size (r = 0.63, p = 0.0004), whereas the extent of ischemic myocardium correlated with the decrease in ejection fraction (r = 0.69, p = 0.0001). The defects present during occlusion reversed within a few hours. CONCLUSIONS: Changes in left ventricular function and perfusion develop pari passu during coronary occlusion and are more severe when the left anterior descending artery is occluded. Although a significant correlation exists between the extent of the perfusion defect and the severity of the decrease in ejection fraction, there is a substantial individual variation with respect to changes in both myocardial perfusion and ventricular function during acute coronary occlusion.

Angina Pectoris↗
PubMed1994

Exploring the minimal dose of amiodarone with antiarrhythmic and hemodynamic activity.

Amiodarone in doses of 200 to 400 mg/day has shown promise in secondary prevention trials for reducing mortality in patients surviving myocardial infarction who have complex ventricular ectopy or nonsustained ventricular tachycardia, or both. In an attempt to explore the lowest dose of amiodarone with antiarrhythmic and hemodynamic activity, we studied 48 patients (mean age 53 +/- 11 years, ejection fraction 23 +/- 9%, clinical heart failure in 85%) with nonsustained ventricular tachycardia. This was a 3-month, randomized, parallel, double-blind pilot study comparing placebo (n = 16) with amiodarone 50 mg/day (n = 15) and 100 mg/day (n = 17). Patients randomized to amiodarone received a mean loading dose of 422 mg/day for the first study week. At the end of the 12 weeks, amiodarone (100 mg) significantly reduced ventricular premature complexes (177 +/- 64 to 98 +/- 38/hour), couplets (8 +/- 3 to 4 +/- 2/hour), and runs of nonsustained ventricular tachycardia (13 +/- 7 to 3 +/- 2/day), all p < 0.01 versus baseline. In addition, 10 of 14 patients taking 100 mg/day had total suppression of nonsustained ventricular tachycardia compared with 4 of 15 taking placebo, p = 0.021. Left ventricular ejection fraction improved by > or = 7% (absolute) in 11 of 29 patients taking amiodarone as compared with only 1 of 15 placebo patients (p = 0.02). In these 11 patients with the greatest measurable hemodynamic improvement, amiodarone significantly increased ejection fraction (21 +/- 7% to 33 +/- 11%, p < 0.01), stroke volume index (28 +/- 9 to 40 +/- 7 ml/m2, p < 0.01) and decreased end-systolic volume index (116 +/- 48 to 92 +/- 44 ml/m2, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Safety of single-site adenosine thallium-201 scintigraphy.

The diagnostic accuracy, safety and tolerance of adenosine thallium scintigraphy have been reported using a 2-site intravenous infusion with either a titrated or fixed-dose protocol. A single-site infusion would considerably simplify the test procedure, but its safety must be established before it can be recommended. Accordingly, 400 consecutive patients who had adenosine and thallium-201 administered through the same intravenous line were classified into 2 groups. Group I (n = 201) patients received a 7-minute titrated intravenous infusion of adenosine, with an initial dose of 50 micrograms/kg/min that increased at 1-minute intervals to a maximum of 140 micrograms/kg/min. Group II (n = 199) patients received a fixed dose of adenosine at 140 micrograms/kg/min for 6 minutes. Adenosine significantly (p < 0.001) increased heart rate and decreased systolic blood pressure by similar amounts in both groups. Adverse effects occurred more often (88 vs 71%, p < 0.001) and started earlier (2.8 vs 3.6 minutes, p < 0.001) in group II. There was no significant difference in the occurrence of second- and third-degree atrioventricular block between the 2 groups (4.0 vs 5.0%); however, chest pain, flushing and nausea were all more frequent in group II. Severe side effects were seldom seen in either group and occurred in 9 group I and 8 group II patients. Scintigraphic findings were similar in both groups. Transient perfusion defects were seen more often in patients with than without second- or third-degree atrioventricular block (42 vs 21%, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMed1994

Safety profile of adenosine stress perfusion imaging: results from the Adenoscan Multicenter Trial Registry.

OBJECTIVES: The purpose of this study was to determine the safety of adenosine infusion at 140 micrograms/kg per min in conjunction with radionuclide imaging in 9,256 consecutive patients. BACKGROUND: Adenosine produces maximal myocardial hyperemia directly with a rapid onset of action. In addition, when used in conjunction with radionuclide perfusion imaging, it has proven efficacy for the diagnosis of coronary artery disease in patients unable to exercise. Because the ultrashort half-life (< 10s) allows dose titration and rapid reversal of side effects, it may be safer than other available pharmacologic agents. METHODS: Patients were prospectively entered at 21 clinical sites. Information on safety and adverse events during and immediately after adenosine infusion was maintained in the Adenoscan Multicenter Trial Registry. RESULTS: The infusion protocol was completed in 80% of patients, required dose reduction in 13% and was terminated early in 7%. Interpretable imaging studies were obtained in 98.7% of patients, and 0.8% of patients received aminophylline. Minor and well tolerated side effects were reported in 81.1% of patients. There were no deaths, one myocardial infarction, seven episodes of severe bronchospasm and one episode of pulmonary edema. Transient atrioventricular (AV) node block occurred in 706 patients (first-degree in 256, second-degree in 378 and third-degree in 72) and resolved spontaneously in most patients (n = 508) without alteration in the adenosine infusion. There were no sustained episodes of AV block. Patients > 70 years of age had an increased risk of developing AV block (age < 70, 7.05% vs. > or = 70, 9.44%, p = 0.001, relative risk 1.37). CONCLUSIONS: Adenosine infusion is safe. Vasodilator and negative dromotropic side effects are generally well tolerated. Serious side effects are relatively rare, and they reverse with termination of adenosine infusion. Interpretable radionuclide studies were obtained in 98.7% of patients and aminophylline reversal was seldom required.

Adenosine↗
PubMed1994

Transdermal nitroglycerin patch therapy reduces the extent of exercise-induced myocardial ischemia: results of a double-blind, placebo-controlled trial using quantitative thallium-201 tomography.

OBJECTIVES: This study prospectively evaluated whether transdermal nitroglycerin patches could limit the extent of exercise-induced left ventricular ischemia as assessed by quantitative thallium-201 tomography. BACKGROUND: Although antianginal medications are effective at reducing chest pain symptoms in patients with coronary artery disease, there is limited evidence that these agents can also reduce myocardial ischemia. METHODS: This was a randomized, double-blind, parallel, placebo-controlled trial evaluating nitroglycerin patch therapy in patients in stable condition with angiographic coronary artery disease and no previous myocardial infarction. All patients were weaned from antianginal agents and had a baseline symptom-limited treadmill test followed by thallium-201 tomography. Forty patients with perfusion defects involving > or = 5% of the left ventricle were randomized to receive either intermittent (12 h on/off) active nitroglycerin patch therapy (0.4 mg/h) or placebo. Exercise tomography was repeated a mean (+/- SD) of 6.1 +/- 1.8 days after randomization. RESULTS: Patients randomized to receive active patch therapy had a significant reduction in their total perfusion defect size (-8.9 +/- 11.1%) compared with placebo-treated patients (-1.8 +/- 6.1%, p = 0.04), which was most apparent in those with the largest (> or = 20%) baseline perfusion defects (-11.4 +/- 13.4% vs. 1.0 +/- 3.6%, respectively, p < 0.02). Furthermore, 7 (33%) of 21 patients receiving active therapy had a > or = 10% decrease in their perfusion defects compared with only 1 (5%) of 19 patients randomized to receive placebo (p = 0.002). Nitrate therapy did not significantly reduce heart rate, blood pressure or double product, indicating benefit through enhancement of coronary blood flow. CONCLUSIONS: Short-term, intermittent nitroglycerin patch therapy significantly reduces myocardial ischemia, particularly in patients with large ischemic perfusion defects. Thallium-201 tomography can be used to assess sequential changes in the extent of exercise-induced left ventricular ischemia.

Administration, Cutaneous↗
PubMed1994

Current status of myocardial perfusion imaging after percutaneous transluminal coronary angioplasty.

Controversy exists with regard to the diagnostic accuracy and optimal technique of myocardial perfusion imaging after coronary angioplasty. Exercise treadmill testing is inexpensive, with adequate predictive value for restenosis and clinical events in patients with single-vessel coronary angioplasty with a normal rest electrocardiogram (ECG). Myocardial tomography has advantages for assessing patients with multivessel coronary angioplasty. Exercise stress imaging is generally preferable to pharmacologic stress in patients without physical limitations after angioplasty. Delayed thallium-201 imaging and reinjection protocols may be useful to reconcile whether residual ischemia exists in "fixed" perfusion defects. Appropriately timed stress myocardial perfusion imaging 2 to 4 weeks after procedurally successful coronary angioplasty can document improved cardiac functional capacity and reduced ECG and imaging evidence of myocardial ischemia. Although routine serial postangioplasty evaluations cannot be recommended, stress myocardial imaging may be valuable in subjects with defective anginal nociception or extensive myocardium at risk in the area subtended by the angioplasty vessel.

Angioplasty, Balloon, Coronary↗
PubMed1994

Pernicious anemia manifesting as angina pectoris.

Here we describe a case of angina pectoris in a patient for whom an extensive cardiovascular workup was done, with negative results. Eventually, the cause of his symptoms was found to be pernicious anemia. Although angina is an uncommon manifestation of pernicious anemia, a review of the literature suggests that the correlation between anemia and angina has been well described. Our case highlights an important differential diagnosis to consider for patients with exercise-induced chest pain and serves to emphasize the attention that should be focused on simple screening laboratory studies. The emphasis in this case is the sequence in which the studies are done. A simple complete blood count with proper interpretation and intervention at the outset of evaluation could possibly have prevented a number of unnecessary, invasive, and costly studies.

Aged↗
PubMed1994

Comparison of ventricular function in atrial rate adaptive versus dual chamber rate adaptive pacing during exercise.

The hemodynamic effects of two different pacing modes--rate adaptive atrial (AAIR) versus dual chamber (DDDR) pacing--were assessed in 12 patients with DDDR pacemakers during upright bicycle exercise first-pass radionuclide angiography using a multiwire gamma camera with tantalum-178 as a tracer. All patients had sinus node disease with intact AV conduction. Patients exercised to the same heart rate in random order in these two different pacing modes, AAIR and DDDR with AV delay (of 100 msec) selected to maintain 100% ventricular capture. Cardiac output increased significantly above baseline values during exercise in both pacing modes: 154 +/- 41% (mean +/- SEM, P = 0.002) with AAIR, versus 95 +/- 24% (P = 0.004) with DDDR (P = NS between the two modes). The peak filling rate, likewise, increased in both pacing modes (2.3 +/- 0.21 end-diastolic volumes/sec to 3.8 +/- 0.31 end-diastolic volumes/sec in AAIR [P = 0.0004] and 2.2 +/- 0.18 end-diastolic volumes/sec to 3.4 +/- 0.27 end-diastolic volumes/sec in DDDR [P = 0.0008]). LV ejection fraction was normal at rest (60 +/- 4%, SEM) and did not significantly change with submaximal exercise in either pacing mode (both 56%, P = NS). No significant changes in end-diastolic volume or stroke volume indexes occurred with exercise in either pacing mode. Our study demonstrates that in patients with normal resting LV function, AAIR and DDDR pacing are equally effective in attaining appropriate increases in cardiac output and LV filling during exercise.

Adult↗
PubMed1994

Myocardial perfusion imaging during pharmacologic stress testing.

Pharmacologic stress testing has gained wide acceptance as an alternative to exercise stress testing when combined with myocardial perfusion scintigraphy and has expanded the applicability of cardiac imaging to the large number of patients who wither cannot exercise or are limited to a submaximal effort. The pharmacologic stressors presently available are either coronary vasodilators (e.g., adenosine, dipyridamole) or beta-agonists (e.g., dobutamine). This article summarizes the physiologic principles underlying pharmacologic stress imaging and its clinical utility in evaluating patients with suspected coronary artery disease.

Adenosine↗
PubMed1994

Exercise and pharmacologic stress testing for prognosis after acute myocardial infarction.

To evaluate patients after acute myocardial infarction (MI), myocardial perfusion imaging provides prognostic parameters that help identify patients at risk for subsequent cardiac events. In addition, myocardial perfusion imaging can be used to identify functionally important residual stenoses and multivessel disease, even in patients who have received thrombolytic therapy. Three parameters of myocardial perfusion imaging emerge as strong predictors of future cardiac events in post-MI patients: (1) presence of transient defects, (2) the number of transient defects and (3) increased radiotracer uptake in the lung. In addition, radionuclide left ventricular ejection fraction (LVEF) is one of the most powerful predictors of subsequent risk for cardiac events, particularly cardiac death and congestive heart failure. Cardiac catheterization, for the most part, does not add to the prognostic value of radionuclide stress testing. Results of myocardial perfusion imaging studies that employ pharmacologic stress instead of submaximal exercise provide strong predictors of prognosis in post-MI patients.

Adenosine↗
PubMed1994

Dobutamine myocardial perfusion imaging.

Dobutamine, a pharmacologic stressor, is useful for myocardial perfusion imaging in patients who cannot exercise. Patients with asthma or severe chronic obstructive pulmonary disease who are at risk for adverse effects from either dipyridamole or adenosine are prime candidates for dobutamine perfusion studies. Dobutamine is a predominant beta-1 agonist that increases heart rate, myocardial contractility and systolic blood pressure. The sensitivity and specificity of dobutamine myocardial perfusion imaging are comparable, for the most part, to those from perfusion studies using exercise, dipyridamole or adenosine.

Coronary Circulation↗
PubMed1993

Therapeutic significance of exercise-induced ST-segment elevation in patients without previous myocardial infarction.

Twelve patients with exercise-induced ST-segment elevation without prior myocardial infarction, electrocardiographic evidence of left ventricular hypertrophy or left bundle branch block underwent thallium-201 tomography immediately after exercise and 4 hours later. Coronary angiography and left ventriculography were performed within an average of 8 days of exercise testing. Five patients had repeat exercise thallium-201 tomography after medical therapy or revascularization. All patients had large, reversible perfusion defects (average defect size 33.5 +/- 13%), with 11 of 12 patients having a > or = 25% stress perfusion defect. In 10 patients with atherosclerotic coronary artery disease, the average stenosis of the involved vessel was 93 +/- 9% (range 70 to 100). The electrocardiographic leads with ST-segment elevation predicted the site of reversible hypoperfusion. Two patients had extensive, reversible anterior hypoperfusion due to exercise-induced spasm of minimally stenosed left anterior descending coronary arteries. Follow-up exercise testing in 5 patients showed abolition of reversible hypoperfusion and ST changes after medical therapy or revascularization. In patients without prior myocardial infarction, exercise-induced ST-segment elevation signifies extensive, reversible hypoperfusion that can be abolished by revascularization in patients with critical coronary stenoses and by medical therapy in those with coronary vasospasm.

Adult↗