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Query: UMLS:C0012833 (dizziness)
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Ten years ago a clinical method of recording the electrical activity of the His bundle in man with transvenously inserted electrodes was described. His bundle recording has permitted the breakdown of the P-R interval into three conduction intervals, i.e., intraatrial (P-A), A-V nodal (A-H), and His-Purkinje system (H-V). His bundle studies have demonstrated our inability to accurately predict from the surface electrocardiogram the exact location of most A-V blocks. First- and second-degree A-V block can occur in the atrium, A-V node or His-Purkinje system, and third-degree A-V block in the A-V node or His-Purkinje system. However, Mobitz type II block almost always occurs below the A-V node. Intraventricular conduction defects, especially of the so-called bifascicular block, have a high incidence of H-V time prolongation, indicating additional disease of the third fascicle or the main His bundle. The prognostic value of a prolonged H-V time in patients with and without chronic conduction defects remains controversial, with some agreement that patients with unexplained syncope or dizziness, normal sinus rhythm and 1:1 conduction, who show prolonged H-V times, should probably be paced permanently. No long-term studies exist regarding the value of the H-V time in predicting death or A-V block in patients with conduction defects secondary to acute myocardial infarction, congenital heart disease or after cardiac surgery. Electrophysiological studies have been extremely useful in the diagnosis and management of patients with accessory pathways and in the evaluation of ventricular and supraventricular arrhythmias. The most valuable test in diagnosing sinus node dysfunction is the sinus node recovery time. A clearly abnormal test in a patient with unexplained syncope or dizziness predicts an almost one hundred per cent relief of symptoms with permanent pacing.
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PMID:Diagnostic and prognostic value of intracardiac electrophysiological studies. Ten years of experience. 38 29

Although analysis of the surface electrocardiograms is usually sufficient in the diagnosis and management of patients with cardiac arrhythmias, electrophysiologic studies can improve diagnostic, therapeutic, and prognostic decisions. Indications for electrophysiologic studies appear to include the following: (1) asymptomatic patients with chronic second degree AV block, both type I and type II with or without bundle branch block; (2) asymptomatic patients with complete AV block; (3) symptomatic patients with bundle branch block and 1:1 AV conduction; (4) patients with bundle branch block complicating acute myocardial infarction; (5) patients with electrocardiograms suggesting pseudo AV block; (6) symptomatic patients with sinus bradycardia, in whom the causal relationship is not clear enough to justify pacing therapy; (7) patients with frequent, troublesome paroxysmal supraventricular tachycardia; (8) patients with Wolff-Parkinson-White syndrome and frequent paroxysmal supraventricular tachycardia; (9) patients with recurrent paroxysmal ventricular tachycardia; (10) patients with syncope or severe dizziness in whom the causal mechanism is not defined.
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PMID:Clinical judgement is not sufficient for the management of conduction defects (indications for diagnostic electrophysiologic studies). 84 90

We reviewed the clinical characteristics and outcome of cases of acute myocardial infarction occurring from January 1, 1985, through December 31, 1987, in the population of a long-term care institution for the elderly. The total number of patients in the series was 43. Comparisons were made between those patients transferred to a general acute-care hospital and those who remained at the facility. The most common initial symptoms of acute myocardial infarction in 32 of 48 patients were, in order, dyspnea, dizziness or syncope, precordial pain, and abdominal pain. Nine (of 43) patients were asymptomatic. In the 14 (of 43) patients transferred to an acute-care hospital, cardiac failure, arrhythmias, and cardiogenic shock were much more frequent than among those retained in the long-term care facility. We concluded that a high index of suspicion for the diagnosis of acute myocardial infarction in the institutionalized elderly is indicated. Patients with mild infarction can be retained in long-term care institutions; resulting mortality from cardiac disorders should be low in adequately staffed and equipped long-term care institutions.
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PMID:Acute myocardial infarction in a long-term care institution for the aged. 173 40

The clinical features of an inner-city population of 304 patients presenting with acute myocardial infarction (MI) with and without typical chest pain, were studied retrospectively. This population consisted of 172 men and 132 women; 155 (51%) were black, 88 (29%) hispanic, and 61 (20%) white, by self-identification. Typical ischemic chest pain was the presenting symptom in 85% (258); 15% (46) presented with nonchest symptoms, most frequently shortness of breath, abdominal pain, and dizziness. But the frequency of such nonchest symptoms was similar in both groups. When patients were grouped by the presence or absence of chest pain, the proportions of those without chest pain were significantly higher for blacks (22.7%) than hispanics (9.1%, P = 0.001) or whites (4.9%, P less than 0.01). Patients without chest pain also had higher admission systolic (P less than 0.01) and diastolic (P less than 0.01) blood pressures and more frequent histories of congestive heart failure (P less than 0.05), and more often presented with pulmonary edema (P = 0.001) than those with chest pain. Both groups were similar in age, sex, history of hypertension, and presence of hypertension on admission, defined as greater than or equal to 160/95 mmHg, prevalence of diabetes, history of smoking, previous MI, type of MI, history of angina, and mortality rates. Patients without chest pain were characterized by black race, history of congestive heart failure, elevated blood pressure and pulmonary edema than those with typical ischemic chest pain. Thus significant delays in the diagnosis and treatment of this important clinical entity may be reduced by alerting clinicians to these features and by educating selected patient groups.
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PMID:Clinical features of patients with acute myocardial infarction presenting with and without typical chest pain: an inner city experience. 252 Aug 50

To evaluate the feasibility and the utility of an integrated service for the pre-hospital diagnosis and care of cardiovascular emergencies a new pre-hospital intensive care system has been developed. Such an emergency medical service relies on the telephone transmission of ECG and the conversation between the first aid service and the cardiologist of the hospital coronary care unit. It also implies early therapeutic intervention performed at home under the responsibility of the chief physician of the referring centre. From March '86 to December '88, 311 telephone ECG transmissions were obtained; the home diagnosis and the consequent proper therapeutic regimen were considered sufficient to avoid the transportation of the patient to the hospital emergency room in 43% of the cases. The symptoms were: precordial chest pain (54%); palpitations (10%); dyspnea (8.4%); hypertensive crisis (1.3%), dizziness or syncope (12.3%). Pre-surgical or organ transplantation controls totaled 13.5%. One-hundred-forty-eight patients were admitted to the coronary unit because of an acute myocardial infarction between June and December 1988. Forty-seven patients were sent by the family doctor (group I) and 30 patients by the first aid service (group II) without any electrocardiographic diagnosis or home therapy; 14 patients were sent by the first aid service after a telephone transmission of ECG and early therapeutic intervention (group III); 57 patients reached the hospital independently (group IV). The following differences among the groups were observed: only the patients of group III received proper early therapeutic regimen at home, and 85% were admitted within 4 hours of the onset of symptoms (vs 46% of the patients of the other groups).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Integration of the hospital coronary care unit with the first aid service for the domiciliary treatment of cardiovascular emergencies]. 280 98

Nitrate usage worldwide is on the increase as the indications for therapy expand. Present indications for nitrate therapy include chronic stable angina pectoris, unstable angina pectoris, complications of acute myocardial infarction, and 'unloading' therapy for acute and chronic congestive heart failure. Nitrates are also being used in the operating suite by anaesthesiologists to control systolic blood pressure during various surgical procedures. New nitrate delivery systems have recently become available which provide considerable dosing flexibility, further increasing the interest in this group of compounds. The dominant action of nitrates is a direct effect on vascular smooth muscle, producing vasodilation of the veins and arteries. These drugs decrease myocardial work by lowering systolic blood pressure, systemic vascular resistance, and reducing intracardiac dimensions. In addition, nitrates have a potent effect on cardiac preload as a result of systemic venodilatation. There is also some evidence that nitrates exert direct effects on the coronary circulation (vasodilatation of coronary arteries and coronary collateral vessels, and direct atherosclerotic stenosis dilatation). These actions may play a role in relieving myocardial ischaemia. Adverse sequelae of nitrate therapy are well known and serious adverse reactions are uncommon. Headache and dizziness are the most frequent side effects. Nitrate tolerance is a definite problem - present evidence indicates that long acting formulations, high doses, or frequent dosing regimens are particularly likely to induce vascular tolerance to nitrates. Consequently, provision of a nitrate-free interval has taken on increasing significance as a strategy to avoid tolerance. Nitrate delivery systems are numerous. Although availability varies from country to country, in most countries there are a wide variety of formulations of glyceryl trinitrate (nitroglycerin) available, including sublingual and oral tablets, oral spray, topical ointment as well as discs or patches for transdermal administration, a transmucosal tablet and an intravenous formulation. Similar formulations of isosorbide dinitrate, except buccal tablets, are available in some countries. Isosorbide 5-mononitrate, a potent metabolite of isosorbide dinitrate, is achieving increasing popularity as an antianginal drug. Optimum nitrate therapy requires a good understanding of the properties of the various formulations, particularly onset and duration of action and propensity to induce tolerance.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Glyceryl trinitrate (nitroglycerin) and the organic nitrates. Choosing the method of administration. 311 8

Bepridil is an investigational calcium channel blocking agent with antianginal activity that has a distinct and complex pharmacologic profile. Bepridil produces significant coronary vasodilation and modest peripheral effects, in addition to negative inotropic and chronotropic effects. Bepridil favorably modifies both myocardial oxygen demand and supply, supporting its use as an antianginal drug. Electrophysiologically, bepridil exhibits classes I, III, and IV antiarrhythmic activity. Five U.S. trials evaluating the short-term antianginal efficacy of bepridil collectively reported that bepridil causes significant improvement in both subjective and objective parameters of efficacy without depressing left ventricular function. In addition, one U.S. trial reported continued antianginal effects of bepridil after long-term use. There are limited data comparing and/or combining bepridil with other antianginal drugs, but the available information is promising. Limited information also exists on the use of bepridil in acute myocardial infarction and arrhythmias. Tolerance to bepridil therapy has been excellent, with the most common adverse effects being diarrhea and dizziness. It is unclear whether bepridil will be used as a first-line agent in the treatment of chronic stable angina pectoris; however, its long half-life, which makes once daily dosing possible, is certainly a significant advantage.
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PMID:Bepridil: a new long-acting calcium channel blocking agent. 330 Dec 44

From the district Haarlem-Noord, 558 patients suffering from an acute myocardial infarction (AMI) were admitted in the years 1982 through 1985. Of these patients 62.9% was 65 years or older, 63.6% was male. The chance of getting an AMI was 8 times greater for the elderly than for younger people, which is in agreement with figures in the whole country. The most important feature--precordial pain--was less frequent in the elderly, i.e. 63.8% compared to 87% for younger people. However, the elderly suffered more from less specific symptoms as breathlessness, heartfailure, dizziness, syncope, neurological and psychiatric symptoms. The frequency of these symptoms varied from 4.5 to 30%. This is 2 to 5 times higher than for people younger than 65 years old. The mortality rate was 31% for people older than 65 years. This was significantly higher than the rate for younger patients (7.7%).
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PMID:[Clinical presentation of acute myocardial infarct in the elderly]. 343 31

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

In a randomized double-blind study with flexible dosage, morphine, nicomorphine and pethidine were compared with regard to analgetic effect, dose requirements, dose intervals and adverse reactions. A total of 275 patients were included, and 28 patients were excluded due to adverse reactions (n = 16) and for practical reasons, etc. Acute myocardial infarction (AMI) was diagnosed in about 60% of the patients, and about 30% had ischemic heart disease without AMI. All three analgesics provided equally efficient pain relief in relative doses of morphine 10, nicomorphine 10 and pethidine 75 mg/ml. Severe adverse reactions were few (allergy 3 cases, respiratory insufficiency 4, severe bradycardia 4), whereas nausea was recorded in 20-30%, vomiting in 5-15% and dizziness in 10-30% of the patients, with no difference between the three drugs. Significant blood pressure drop (greater than 30 mmHg) was seen in 3-8% of the patients, with no significant differences between the drugs.
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PMID:Analgetic treatment in acute myocardial infarction. A controlled clinical comparison of morphine, nicomorphine and pethidine. 637 74


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