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Query: UMLS:C0012833 (dizziness)
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Within a half-year period, we encountered six cases of patients harmed by the adverse effects of self-administered nitroglycerin--syncope, delayed definitive medical care, and the worsening of nonischemic symptoms. We therefore surveyed 112 patients after a remote myocardial infarction, and 121 cardiologists and internists, regarding the use of sublingual nitroglycerin. Of the physicians, 84 percent routinely prescribed nitroglycerin to patients after a myocardial infarction, and 79 percent of the patients had the tablets available (83 percent of these, at all times). Most patients used the tablets less than once per month, and 37 percent of the patients who always carried nitroglycerin had not used it at all during the preceding year. Although 89 percent of the patients claimed to know when to use the drug, 57 percent had used it or would use it for symptoms such as dizziness, rapid heartbeat, or presyncope. All patients having nitroglycerin claimed it relieved their symptoms, even if the relief was only partial, the time elapsed until relief could not be specified, and the symptoms were of a type unlikely to be relieved by the drug. We suggest that the practice of routinely prescribing nitroglycerin to patients after a myocardial infarction should be reassessed.
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PMID:Defining the proper role for self-administered sublingual nitroglycerin. A survey of physicians and patients. 190 18

Clinical data on 3,911 patients were collected from 64 individual investigators to evaluate the safety of intravenous dipyridamole-thallium imaging as an alternative to exercise thallium imaging for the evaluation of coronary artery disease. There were two deaths because of myocardial infarctions, two nonfatal myocardial infarctions, and six cases of acute bronchospasm. Chest pain occurred in 770 patients (19.7%). Headache and dizziness were reported by 476 patients (12.2%) and 460 patients (11.8%), respectively. ST-T changes on the electrocardiogram were seen in 292 patients (7.5%). Use of parenteral aminophylline to treat adverse events associated with intravenous dipyridamole brought complete relief of symptoms in 439 of 454 patients (96.7%). There is a potential for increased risk for serious ischemic events in patients with a history of unstable angina who are administered intravenous dipyridamole. In patients with acutely unstable angina (i.e., continuing chest pain) or in the acute phase of myocardial infarction, use of intravenous dipyridamole in thallium scintigraphy should be avoided. There is also an increased risk for bronchospasm in patients with a history of asthma; acute bronchospasm can be relieved immediately by administration of aminophylline. These results demonstrate that intravenous dipyridamole-thallium scintigraphy is a relatively safe, noninvasive technique for the evaluation of coronary artery disease.
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PMID:The safety of intravenous dipyridamole thallium myocardial perfusion imaging. Intravenous Dipyridamole Thallium Imaging Study Group. 231 20

The chemistry, pharmacology, pharmacokinetics, clinical efficacy, adverse effects, and dosage of the Class I antiarrhythmic agent moricizine hydrochloride are reviewed. Moricizine is chemically similar to the phenothiazines but does not appear to block dopaminergic receptors. Its major electrophysiologic actions are a concentration-dependent decrease in maximum rate of phase 0 depolarization; increased rates of phase 2 and 3 repolarization, decreased action potential duration, and decreased effective refractory period. Moricizine causes a dose-related prolongation of the PR interval and of AV nodal, infranodal, and intraventricular conduction times but has little effect on ventricular repolarization. The antiarrhythmic and electrophysiologic effects are not correlated with plasma concentrations of the drug or its metabolites. Moricizine reduces the occurrence of ventricular premature contractions (VPCs), couplets, and nonsustained ventricular tachycardia. It appears to suppress symptomatic nonsustained ventricular tachycardia, sustained ventricular tachycardia, and ventricular fibrillation or flutter. Moricizine appears to be as effective as quinidine and more effective than disopyramide, propranolol, and imipramine but less effective than flecainide and encainide at reducing VPCs. Moricizine continues to be evaluated in the Cardiac Arrhythmia Suppression Trial, which was designed to assess the long-term benefit of arrhythmia suppression in patients with left ventricular dysfunction after myocardial infarction. Moricizine seems to be better tolerated than quinidine, disopyramide, and imipramine and to have less proarrhythmic potential than flecainide or encainide. Noncardiac adverse effects include dizziness, nausea, and headache. Cimetidine appears to decrease moricizine clearance, and decreased theophylline clearance has been reported in subjects given moricizine. The usual adult dosage of moricizine hydrochloride is 600-900 mg/day given in three divided doses; an every-12-hour regimen may be used in some patients. Because of the risk of proarrhythmic effects, indications are limited to treatment of documented life-threatening arrhythmias. Moricizine will compete with other agents as first-line therapy for life-threatening arrhythmias.
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PMID:Moricizine: a new class I antiarrhythmic. 227 51

Key safety parameters of sotalol were examined in 1,288 patients entered into recent controlled trials of ventricular (85% of patients) or supraventricular arrhythmias (15%). Most patients were middle-aged male Caucasians with significant heart disease. The most serious adverse event was proarrhythmia, occurring in 56 patients (4.3%). Of these, 27 had hemodynamic compromise due to malignant ventricular arrhythmias. Most had a history of sustained ventricular tachycardia, myocardial infarction, congestive heart failure (CHF) or cardiomyopathy, or a combination of these. The other 29 had nonsevere events; 38% continued taking sotalol. Proarrhythmia was manifested by torsades de pointes in 24 of the 56 patients. No universal causal relation was found with commonly associated factors such as bradycardia, hypokalemia and long QT interval. The mean QT and QTc at baseline within 1 week of a severe proarrhythmic event were greater than those of patients not having proarrhythmia. Nineteen patients (1%) discontinued therapy with sotalol because of drug-related CHF. Predisposing conditions included low initial baseline ejection fraction, history of CHF, cardiomyopathy or cardiomegaly, or both, male gender and age greater than 65 years. Heart failure usually occurred within 7 to 30 days of initiating therapy. The most common reason for premature discontinuation of the drug in patients treated for sustained ventricular tachycardia was ineffectiveness (39%), whereas adverse effects were the most common reasons among patients treated for complex ventricular ectopy (21%). Dyspnea and bradycardia were the most common cardiovascular effects, and fatigue, dizziness and asthenia the most common noncardiac, adverse effects. Although frequently reported, these adverse effects resulted in discontinuation of only 1 to 4% of the patients at risk.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Clinical safety profile of sotalol in patients with arrhythmias. 240 37

To assess the efficacy and safety of cibenzoline, 18 patients with symptomatic premature ventricular complexes (30/h or more) on baseline 48 h Holter monitors were randomized to oral cibenzoline versus placebo. The cibenzoline and placebo doses were increased from 130 to 160 mg bid after one week if premature ventricular complex (PVC) suppression was less than 75%. The double-blind placebo controlled phase (phase 1) lasted for two weeks prior to the open label long term study (phase 2). Efficacy was defined as suppression of at least 75% PVCs, 85% couplets and 90% ventricular tachycardia on follow-up 48 h Holter monitoring. At the six month mark of phase 2, patients were placed on placebo for seven days to evaluate for spontaneous resolution of PVCs. Of the seven patients on cibenzoline in phase 1, four had a positive response, one had partial control (73% suppression of PVCs) and two noted dizziness and withdrew. Of the 11 patients randomized to placebo, nine noted no change, two had a significant decrease in PVCs and one noted dizziness and withdrew. Fifteen patients were enrolled in phase 2 on open label cibenzoline at 130 to 160 mg bid. At a mean follow-up of 17 +/- 4 months (range 12 to 25), eight patients had control of symptomatic ventricular arrhythmias without adverse effects, three patients did not respond to cibenzoline, one had PVC recurrence after initial control on cibenzoline, one died of myocardial infarction without arrhythmias, one had spontaneous resolution of PVCs and one was withdrawn because of poor compliance. In conclusion, cibenzoline is effective in controlling symptomatic PVCs and is moderately well tolerated.
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PMID:Cibenzoline for symptomatic ventricular arrhythmias: a prospective, randomized, double-blind, placebo controlled trial and a long term open label study. 247 30

AFR 35-11, dated 10 April 1985, included standards for physical fitness performance tests with the option of a 1.5-mile run or a 3-mile walk. Since that time, ANG units have begun initial physical fitness testing of all personnel. This program brought with it new responsibilities for ANG medical units including the screening of individuals in whom health problems might indicate that they are at risk in taking the physical fitness test (PFT). The 111th TAC Clinic used a questionnaire, screened by physicians utilizing a predetermined grid of responses to designate individuals cleared for the run or walk test or as at risk. Of 823 individuals screened, 91 (11%) were designated at risk. These individuals are being further evaluated and 31 (29%) have been subsequently cleared to date. Physical testing of cleared individuals was accomplished, and both running and walking courses were carefully monitored by ambulance crews. Four casualties came to medical attention (blisters, severe fatigue, dizziness, and indigestion). The patient with severe fatigue was a patient on medical hold, S/P myocardial infarction, who had not been medically cleared to participate. The patient with light-headedness was found to have newly diagnosed hypertension. In view of the relatively small number of casualties incurred during this initial PFT, it is felt that the screening process employing a questionnaire evaluated by medical personnel is an appropriate method of minimizing risk.
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PMID:Report of an Air National Guard clinic's experience with screening at-risk individuals before initial physical fitness testing. 250 60

During the intervening years since metoprolol was first reviewed in the Journal (1977), it has become widely used in the treatment of mild to moderate hypertension and angina pectoris. Although much data have accumulated, its precise mechanisms of action in these diseases remain largely uncertain. Optimum treatment of hypertension and angina pectoris with metoprolol is achieved through dose titration within the therapeutic range. It has been clearly demonstrated that metoprolol is at least as effective as other beta-blockers, diuretics and certain calcium antagonists in the majority of patients. Although a twice daily dosage regimen is normally used, satisfactory control can be maintained in many patients with single daily doses of conventional or, more frequently, slow release formulations. Addition of a diuretic may improve the overall response rate in hypertension. Several controlled trials have studied the effects of metoprolol administered during the acute phase and after myocardial infarction. In early intervention trials a reduction in total mortality was achieved in one moderately large trial of prolonged treatment, but in another, which excluded patients already being treated with beta-blockers or certain calcium antagonists and where treatment was only short term, mortality was significantly reduced only in 'high risk' patients. Overall results with metoprolol have not demonstrated that early intervention treatment in all patients produces clinically important improvement in short term mortality. Thus, the use of metoprolol during the early stages of myocardial infarction is controversial, largely because of the requirement to treat all patients to save a small number at 'high risk'. This blanket coverage approach to treatment may be more justified during the post-infarction follow-up phase since it has been shown that metoprolol slightly, but significantly, reduces the mortality rate for periods of up to 3 years. Metoprolol is generally well tolerated and its beta 1-selectivity may facilitate its administration to certain patients (e.g. asthmatics and diabetics) in whom non-selective beta-blockers are contraindicated. Temporary fatigue, dizziness and headache are among the most frequently reported side effects. After a decade of use, metoprolol is well established as a first choice drug in mild to moderate hypertension and stable angina, and is beneficial in post-infarction patients. Further study is needed in less well established areas of treatment such as cardiac arrhythmias, idiopathic dilated cardiomyopathy and hypertensive cardiomegaly.
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PMID:Metoprolol. An updated review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy, in hypertension, ischaemic heart disease and related cardiovascular disorders. 294 80

A data base of 1,245 patients treated for ventricular arrhythmias, most of whom had serious cardiac disease, was reviewed. Only 2.9% of these patients had benign ventricular arrhythmias without structural heart disease. The overall incidence of proarrhythmia in this population was 9.2% (115/1,245), but was as frequent as 16% in patients with a history of cardiomyopathy. The proarrhythmic form was new sustained ventricular tachycardia in 22 patients (1.8%). Only 2 of 71 patients (2.8%) with primary arrhythmia had a proarrhythmic event. The incidence has decreased markedly over the past years as reduced doses and gradual titration have been used. There were 137 deaths in the data base of which 82 were sudden, all in patients with advanced (79) or moderately severe (3) cardiac disease. High initial doses, prior myocardial infarction and congestive heart failure (CHF) were positively associated with sudden cardiac death. There were no deaths among the 71 patients with benign arrhythmias. Death rates were related to the severity of the arrhythmia being treated. Comparisons with published survival curves indicated modest improvement; in no case was survival decreased. Invasive and noninvasive measures of left ventricular function indicated no adverse hemodynamic effects. There was only 1 case of new and 3 cases of worsened CHF probably related to encainide. Only 5 patients discontinued for CHF or related signs and symptoms. The most frequent drug-related noncardiac adverse reactions were dizziness (26%), abnormal or blurred vision (19%), QRS interval prolongation (5%), taste perversion (4%) and tremor (3%). In conclusion, the use of reduced doses and gradual titration of encainide has markedly decreased the incidence of proarrhythmia.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Safety of encainide for the treatment of ventricular arrhythmias. 309 26

The authors present a retrospective study of 46 consecutive patients aged from 70 to 79 years (mean 73.3 +/- 2.5 years) with suspected coronary artery disease who, being unfit for exercise tests, were explored by myocardial scintigraphy with thallium 201 after coronary dilatation with intravenous dipyridamole. The examination was well tolerated by 30 patients. Such classical side-effects as chest pain, malaise, dizziness, headache, flushing, vomiting and transient arrhythmia or repolarization disorders were recorded, but they were not more frequent than in younger subjects. However, the occurrence of severe hypotensive malaise relieved by theophylline in two cases and of angina in about one third of patients with myocardial ischaemia means that the procedure must be performed under close supervision. A fall in blood pressure (-11 mmHg on average) and a rise in heart rate (+8 beats/min on average) were usual. Post-scintigraphy follow-up of patients over a mean period of 11.1 +/- 6.2 months showed that a reversible defect of thallium 201 uptake, due to redistribution, is a highly selective indicator of patients who are particularly exposed to a cardiac accident in the short--or mid-term. Only one out of 26 patients without reversible ischaemia (4 p. 100) subsequently presented with a major coronary event (unstable angina). In contrast, in the group of 20 patients with reversible ischaemia three required early myocardial revascularization; furthermore, five serious accidents (29 p. 100) occurred among the 17 patients who were left under medical treatment, including two sudden deaths, two cases of unstable angina and one case of myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Tolerance and prognostic value of Thallium 201 myocardial tomoscintigraphy with dipyridamole in the aged subject]. 314 28

To assess the predictive value of ventricular late potentials and programmed ventricular stimulation, 379 patients without a history of sustained ventricular tachycardia, dizziness or syncope were studied prospectively. Group I included patients referred for coronary angiography. Group II consisted of patients who survived an episode of acute myocardial infarction and who were studied within 6 weeks after onset. During follow-up (mean 13 months), 16 patients died. Six of these patients died suddenly within one hour. The prevalence of sudden cardiac death was lower (0.8%) in group I compared to group II (3.0%). There was no correlation between results of both methods and the subsequent occurrence of sudden cardiac death. Symptomatic sustained ventricular tachycardia was documented in 10 patients (2.6%). Only one patient in group I later developed symptomatic sustained ventricular tachycardia in contrast to nine cases in group II. Symptomatic sustained ventricular tachycardia could be predicted in patients in the early postmyocardial infarction period (group II). By using various combinations of parameters, the highest predictive value for subsequent sustained ventricular tachycardia was reached by the following combination: Late potentials of 40 ms duration or more, induction of monomorphic sustained ventricular tachycardia at rates below 270 beats min-1 and interval after myocardial infarction less than 6 weeks. In conclusion, both techniques seemed to be promising for the identification of patients at risk of ventricular tachycardia after myocardial infarction.
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PMID:Ventricular late potentials and inducible ventricular tachyarrhythmias as a marker for ventricular tachycardia after myocardial infarction. 372 Jul 67


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