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Biomedical subjects

A Movahed

Publications and source records attributed to A Movahed.

At least 19 recordsLinked to original sources
PubMed2001

Pharmacological stress agents for evaluation of ischemic heart disease.

Ischemic heart disease is the leading cause of death in the developed countries for those older than 65 years of age. In patients suspected to have coronary artery disease a stress test should be performed to identify the vulnerability of the myocardium to ischemia. As a rule of thumb, the evaluation of coronary artery disease is best done by exercise stress test. In patients who are not able to exercise adequately, pharmacological stress agents are used. The commonly used agents are the coronary vasodilators, adenosine and dipyridamole and the catecholamines, dobutamine and arbutamine. These agents are combined with imaging techniques to increase the sensitivity and specificity of the test. These agents have been widely used and have an excellent safety profile. Another advantage in using pharmacological stress agents is that they do not affect the image quality, especially with echocardiography and magnetic resonance imaging. Ongoing developments hold promise for safer and more reliable pharmacological stress agents in the future.

Adrenergic beta-Agonists↗
PubMed2000

Update on digoxin therapy in congestive heart failure.

Congestive heart failure is a progressive disease with significant morbidity and mortality. Despite advances in the prevention and treatment of cardiovascular diseases, the incidence and prevalence of congestive heart failure have increased in recent years. Contributing factors include increased survival in patients with coronary artery disease (especially myocardial infarction), an aging population and significant advances in the control of other potentially lethal diseases. New and existing agents, including angiotensin-converting enzyme inhibitors, beta blockers and, more recently, spironolactone, are being used increasingly to prolong life in patients with heart failure. Although digoxin has been used to treat heart failure for more than 200 years, its role in patients with congestive heart failure and sinus rhythm is still debatable. Over the past decade, digoxin has received renewed attention because of recognition of its neurohormonal effect and the successful use of lower dosages. In recent trials, digoxin has been shown to reduce morbidity associated with congestive heart failure but to have no demonstrable effect on survival. The goal of digoxin therapy in patients with congestive heart failure is to improve quality of life by reducing symptoms and preventing hospitalizations.

Cardiotonic Agents↗
PubMed2000

Right ventricular infarction--diagnosis and treatment.

Right ventricular infarction (RVI) as assessed by various diagnostic methods accompanies inferior-posterior wall myocardial infarction (MI) in 30 to 50% of patients. Recognition of the syndrome of RVI is important as it defines a significant clinical entity, which is associated with considerable immediate morbidity and mortality and has a well-delineated set of priorities for its management. Patients may clinically present with hypotension, elevated jugular venous pulse (JVP), and occasionally shock, all in the presence of clear lung fields. The ST-segment elevation of > or = 0.1 mV in the right precordial leads V4R is a readily available electrocardiographic sign used for diagnosis of RVI. Other diagnostic approaches for assessing RVI include echocardiography, radionuclide ventriculography, technetium pyrophosphate scanning, and hemodynamic measurements. The proper management of RVI includes volume loading to maintain adequate right ventricular preload, ionotropic support, and maintenance of atrioventricular synchrony. Reperfusion therapy should be initiated at the earliest signs of right ventricular dysfunction. Finally, complete recovery over a period of weeks to months is a rule in a majority of patients, suggesting right ventricular "stunning" rather than irreversible necrosis has occurred.

Animals↗
PubMed1998

Indications for anticoagulation in atrial fibrillation.

Factors associated with an increased risk of thromboembolic events in patients with atrial fibrillation (AF) include increasing age, rheumatic heart disease, poor left ventricular function, previous myocardial infarction, hypertension and a past history of a thromboembolic event. Patients with AF should be considered for anticoagulation or antiplatelet therapy based on the patient's age, the presence of other risk factors for stroke and the risk of complications from anticoagulation. In general, patients with risk factors for stroke should receive warfarin anticoagulation, regardless of their age. In patients who are under age 65 and have no other risk factors for stroke, either aspirin therapy or no therapy at all is recommended. Aspirin or warfarin is recommended for use in patients between 65 and 75 years of age with no other risk factors, and warfarin is recommended for use in patients without risk factors who are older than 75 years of age.

Age Factors↗
PubMed1996

Free radical generation and the role of allopurinol as a cardioprotective agent during coronary artery bypass grafting surgery.

OBJECTIVES: To determine the time course of free radical generation and the role of allopurinol as a cardioprotective agent during coronary artery bypass surgery. DESIGN: Patients were chosen on a strict 'first come, first chosen' basis, irrespective of their age and sex. SETTING: Tertiary referral-based hospital and medical research centre. PATIENTS: A total of 36 patients underwent nonurgent coronary artery bypass grafting surgery. Eighteen patients were treated with allopurinol and 18 patients acted as control. INTERVENTIONS: Allopurinol 300 mg was administered orally, twice a day for one day preoperatively and a single dose (600 mg) was administered on the morning of the day of the operation. MEASUREMENTS AND MAIN RESULTS: Lipid peroxidation products were measured by assays for thiobarbituric acid reactive substances, mainly malondialdehyde (MDA). There were no considerable changes in either MDA levels or creatine kinase isoenzyme with muscle and brain subunits (CK-MB) activity during the ischemic period. One minute after release of the cross-clamp the level of MDA was raised significantly (P<0.001). This rise correlated with the severity of ischemia in the group treated with allopurinol as well as the control group (r=0.58, P<0.05 and r=0.49, P<0.05, respectively). The level of MDA and the activity of CK-MB were significantly lower in patients treated with allopurinol (P<0.05 and P<0.001, respectively). The increase in CK-MB activity during reperfusion correlated with aortic cross-clamp time in both the groups (r=0.62, P<0.05 and r=0.69, P<0.05, respectively). Preliminary studies using electron spin resonance spin trapping technique also demonstrated a rise in free radical adducts during reperfusion and this corroborated well with the spectrophotometric method. CONCLUSION: The results of this study show that, during bypass surgery, there is an increase in lipid peroxidation products and cardiac creatine kinase enzyme at the onset of reperfusion indicating increased free radical activity. It also suggests that pretreatment with allopurinol could effectively attenuate post-ischemic reperfusion injury.

Allopurinol↗
PubMed1995

Effect of cocaine on left ventricular function. Relation to increased wall stress and persistence after treatment.

BACKGROUND: To determine whether alterations in left ventricular (LV) function after a cocaine infusion are due to reduced myocardial contractility or changes in loading conditions, we examined LV function in 30 morphine-sedated, closed-chest dogs. We also wanted to determine the time course of the effects of cocaine on LV function after the infusion was stopped. METHODS AND RESULTS: Two-dimensional echocardiography and hemodynamics provided LV fractional shortening and end-systolic wall stress data. Radionuclide ventriculography was also performed. Four groups of dogs received saline or cocaine infusions of 10, 30, or 100 micrograms.kg-1.min-1. Cocaine was infused for 90 minutes with ECG and arterial pressure monitoring. Animals were monitored for an additional 120 minutes after the infusion ended. Arterial pressure rose over the course of the experiment in all four groups, but saline and cocaine 10 micrograms.kg-1.min-1 did not significantly change ejection fraction. Cocaine 30 and 100 micrograms.kg-1.min-1 acutely increased arterial pressure and heart rate but decreased ejection fraction from 0.64 +/- 0.06 to 0.45 +/- 0.08 and from 0.65 +/- 0.10 to 0.46 +/- 0.11, respectively. Additionally, cocaine 100 micrograms.kg-1.min-1 decreased fractional shortening from 36 +/- 9% to 23 +/- 12%. However, cocaine 30 and 100 micrograms.kg-1.min-1 also increased wall stress from 42 +/- 15 to 65 +/- 11 g/cm2 and from 37 +/- 15 to 90 +/- 33 g/cm2, respectively. These results were analyzed by use of the relation between wall stress and fractional shortening as an index of contractility. Fractional shortening after cocaine infusion was displaced downward as a result of increased wall stress rather than changes in contractility. In addition, alteration of afterload with phenylephrine (6 micrograms/kg) and sodium nitroprusside (10 micrograms/kg) before and during infusion of cocaine 100 micrograms.kg-1.min-1 showed similar regression lines for wall stress to fractional shortening. CONCLUSIONS: Ejection-phase indexes of LV function were reduced by cocaine in this model of conscious, sedated dogs, but effects were attributable to increased wall stress rather than to reduced myocardial contractility. These effects persisted for at least 2 hours after the infusion was stopped.

Angiography↗
PubMed1995

Assessment of cardiac risk in noncardiac surgery.

Surgical techniques have been refined so that complications directly resulting from surgical procedures are relatively small. However, with the high prevalence of coronary artery disease in the United States, many surgical patients have concomitant coronary artery disease. Anesthesia as well as the surgical procedure induce stresses on the heart and circulatory system which could result in perioperative cardiac morbidity and mortality. Assessing patients prior to surgical procedures by history, physical examination, laboratory data, and newer cardiovascular diagnostic procedures can stratify the cardiac risk and help to predict the incidence of perioperative cardiac morbidity and mortality. If great risk exists, an alternative therapy or cancellation of the surgical procedure may be considered. In certain subgroups of patients, coronary artery revascularization, valvular heart surgery, or beginning medical therapy of the underlying cardiac pathology could be performed prior to the surgical procedure. If this cannot be arranged for high-risk patients, more intensive and invasive hemodynamic monitoring and optimal medical management perioperatively might reduce cardiac complications.

Anesthesia↗
PubMed1994

Norepinephrine-induced left ventricular dysfunction in anesthetized and conscious, sedated dogs.

These studies were conducted to evaluate effects of high dose norepinephrine infusion on left ventricular function in anesthetized and conscious dogs. Separate groups of pentobarbital anesthetized closed-chest dogs received norepinephrine infusion for 90 min followed by 1 h of recovery. Arterial pressure, electrocardiogram, two-dimensional echocardiogram and an equilibrium radionuclide angiogram were monitored. One hour following infusion of norepinephrine, left ventricular ejection fraction was reduced in a dose-dependent fashion. Fractional shortening was similarly reduced, with increased left ventricular systolic and diastolic dimensions also observed. Left ventricular end-systolic wall stress was increased at 60 min following infusion of norepinephrine but not saline: saline, 68 +/- 8, norepinephrine, 4 micrograms/kg/min, 113 +/- 8 g/cm2. The left ventricular end-systolic wall stress/fractional shortening relationship showed reduction of contractility. In 10 conscious dogs pretreated with morphine, norepinephrine at 5 micrograms/kg/min x 90 min produced similar changes to those seen in anesthetized animals. Ejection fraction was reduced from 0.69 +/- 0.3 to 0.36 +/- 0.04 at 60 min post infusion. Fractional shortening was also reduced. Left ventricular end-diastolic dimension was increased. However, when animals were followed for 1 week, complete recovery occurred within 48 h. Histology showed mild contraction band necrosis in acute experiments and mild perivascular fibrosis in chronic experiments. Therefore, norepinephrine cardiotoxicity produced significant left ventricular dilation and reduction of ejection phase indices of left ventricular function associated with reduced contractility. In chronic dogs, histologic changes were mild, and left ventricular dysfunction was reversible.

Anesthesia↗
PubMed1994

Electrocardiographic and segmental wall motion abnormalities in pancreatitis mimicking myocardial infarction.

Transient electrocardiographic changes in patients with acute cholecystitis, pancreatitis, and pneumonia have been reported in the past. These changes usually are in the form of T-wave inversion, ST-segment depression, and rarely ST-segment elevation in the absence of coronary artery disease. To the authors' knowledge, this is the first report documenting both left ventricular segmental wall motion abnormality and electrocardiographic changes of myocardial injury in the presence of acute pancreatitis.

Acute Disease↗
PubMed1994

High-grade atrioventricular block during dipyridamole stress testing.

Dipyridamole stress testing may be used in the diagnosis of coronary artery disease and risk assessment of patients who are unable to exercise. Although dipyridamole perfusion imaging has a good safety record, serious side-effects may rarely occur. We present a case in which dipyridamole induced high-grade atrioventricular (AV) block that responded promptly to intravenous aminophylline but not to atropine.

Aged↗
PubMed1994

Tl-201 liver uptake for assessment of jeopardized myocardium during dipyridamole stress testing.

The current study was conducted to determine the significance of Tl-201 liver activity during 4 minute dipyridamole (DP) stress testing. Two groups of subjects were examined: group I subjects (n = 52) had electrocardiographic evidence of left ventricular hypertrophy (ECG-LVH), and group II subjects (n = 114) had no ECG-LVH. Both groups were further divided into four subgroups on the basis of Tl-201 myocardial perfusion scans: 1) no myocardial perfusion defect; 2) transient myocardial perfusion defect; 3) fixed myocardial perfusion defect; and 4) transient plus fixed myocardial perfusion defects. Tl-201 liver, heart, and lung activities were quantified in the immediate anterior planar images. Left ventricular mass was quantified using tomographic short-axis slices. In the no ECG-LVH group, Tl-201 lung-to-heart ratio was significantly increased in subjects having transient, fixed, and transient plus fixed myocardial perfusion defects when compared to no myocardial perfusion defect. Tl-201 lung-to-heart ratio did not increase in the ECG-LVH group of subjects having transient, fixed, and transient plus fixed myocardial perfusion defects. In contrast, Tl-201 liver-to-heart ratio increased in both the ECG-LVH and no ECG-LVH groups of subjects having myocardial perfusion defects when compared to subjects having negative myocardial perfusion scan. Left ventricular mass was increased in ECG-LVH subjects when compared to no ECG-LVH subjects, which might have resulted in increased Tl-201 myocardial uptake and, hence, reduced Tl-201 lung-to-heart ratio in ECG-LVH subjects having myocardial perfusion defects.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Exercise testing in patients with electrocardiographic evidence of left ventricular hypertrophy.

The purpose of this study was to determine the influence of left ventricular hypertrophy, based on electrocardiographic evidence, on the results of exercise thallium testing. Patients with electrocardiographic evidence of left ventricular hypertrophy (ECG-LVH) and suspected of having coronary artery disease underwent exercise thallium testing. Retrospective analysis of 107 consecutive patients with ECG-LVH showed transient myocardial perfusion defects (TMPD) in 12 (11%), indicative of myocardial ischemia; 12 (11%) had fixed myocardial perfusion defects (FMPD), indicative of probable myocardial infarction; 5 had TMPD plus FMPD (5%), and scan results for 78 were normal (73%). In patients with ECG-LVH, additional ST changes were observed in 76% and chest pain in 7% of patients with ECG-LVH. In a matched comparison group of 255 patients not prescreened for ECG-LVH, TMPD was observed in 20%, FMPD in 16%, and TMPD plus FMPD in 26% of patients, and normal results were found in 38%. Electrocardiographic changes were found in 49% and chest pain in 20%. Hemodynamic responses to exercise were comparable between subgroups. Lung thallium uptake was quantified as the lung-to-heart thallium activity ratio (L-H) on the immediate exercise anterior planar images. In controls, a significant increase in L-H was observed in patients with TMPD and TMPD plus FMPD. This was not observed in patients with ECG-LVH, possibly because of elevated thallium myocardial activity as a result of increased left ventricular mass. The conclusion is that patients with ECG-LVH often had normal perfusion scan results (73%) on exercise despite a high incidence of additional ECG changes (76%).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗
PubMed1994

Effect of tobacco abuse on pulmonary thallium uptake during exercise myocardial perfusion scintigraphy.

To determine the influence of tobacco abuse on thallium 201 lung uptake during exercise, we examined 185 consecutive subjects with normal myocardial perfusion scans and without electrocardiographic evidence of left ventricular hypertrophy. The subjects were divided into two groups: group 1 subjects (n = 60) had histories of smoking and group 2 subjects (n = 125) were nonsmokers. Eighty-eight percent of group 1 subjects and 92% of group 2 subjects were examined using single-photon emission computed tomography and the remaining patients underwent planar imaging. 201Tl lung and heart activities were quantified from the immediate anterior planar images that were obtained in all subjects and reported as lung to heart ratio (L/H). 201Tl L/H in smokers (0.39 +/- 0.11) was significantly higher (P < 0.05) than in nonsmokers (0.34 +/- 0.06) when subjects who achieved 85% of the target heart rate were compared. In conclusion, 201Tl L/H was higher in smokers than in nonsmokers when subjects who achieved 85% of the target heart rate and had no myocardial perfusion defects were compared.

Exercise Test↗
PubMed1994

Successful treatment of myocardial sarcoidosis with steroids.

Myocardial involvement in sarcoidosis occurs in approximately twenty-seven percent of patients and may result in a grim prognosis. The diagnosis is mainly clinical and may be supplemented by echocardiography, thallium imaging, Gallium-67 scanning, and myocardial biopsy. The value of corticosteroid treatment is still not well-established and few patients have benefitted from cardiac transplantation. We present a case with suspected myocardial sarcoidosis and congestive heart failure who had dramatic response to steroid therapy on five weeks' followup.

Adult↗