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Biomedical subjects

A P Rae

Publications and source records attributed to A P Rae.

At least 55 records · Page 3Linked to original sources
PubMed1987

Transpulmonary angiotensin II formation in patients with chronic stable cor pulmonale.

The activity of the renin-angiotensin (RA) system and the ability of the lungs to generate angiotensin II (AII) were studied in 11 patients with stable cor pulmonale and respiratory failure caused by chronic obstructive bronchitis and emphysema. Angiotensin I concentrations (18.7 +/- 8.3 pmol/L) were normal, and transpulmonary AII formation rates (TRAIIFR) (14.2 +/- 18.1 pmol/min) were not significantly different from those recorded in nonedematous cardiac subjects (19.9 +/- 20.1 pmol/min), matched for sex, age, and diuretic therapy. The main determinant of TPAIIFR was the mixed venous AI concentration. Administration of oxygen for 30 min led to a small increase in TPAIIFR in the majority of patients. This increase could not be accounted for by changes in mixed venous AI. There was no correlation between serum angiotensin-converting enzyme levels and either the TPAIIFR or the systemic arterial AII concentrations.

Aged↗
PubMed1987

Ultrafiltration in diuretic-resistant cardiac failure.

Ultrafiltration was performed in 13 patients with diuretic-resistant cardiac failure. All patients had severely distressing peripheral edema and ultrafiltration was successfully completed in 12 patients, all of whom sustained symptomatic improvement. The volume of fluid removed ranged from 3.7 to 23 L, mean 11.8 L. Weight reduction produced by ultrafiltration continued over the following week, indicating an improved response to diuretic therapy. Ultrafiltration is an effective therapeutic intervention in the management of a small but well-defined group of patients with diuretic-resistant cardiac failure.

Aged↗
PubMed1986

Plasma norepinephrine in exercise-induced ventricular tachycardia.

The relation between plasma norepinephrine levels and the occurrence of ventricular tachycardia during exercise testing was prospectively evaluated in 17 patients. Ten patients had reproducible ventricular tachycardia exclusively during exercise or recovery, or both; 7 patients had ventricular tachycardia only during ambulatory electrocardiographic monitoring. The two groups did not differ in age, exercise duration, left ventricular ejection fraction at rest, heart rate throughout the exercise protocol, rest QTc interval, change in QTc interval during exercise, the presence of coronary artery disease or exercise-related myocardial ischemia. Furthermore, there was no difference between groups in plasma norepinephrine levels at rest, peak exercise or in the recovery period. Myocardial ischemia was detectable by thallium perfusion scan in only 2 of the 10 patients with exercise-induced ventricular tachycardia. The 10 patients with exercise-induced ventricular tachycardia underwent repeat exercise testing immediately after maximal intravenous beta-adrenergic blockade with propranolol. Although they had no change in exercise duration, ventricular tachycardia did not occur in 9 of these 10 patients. Plasma norepinephrine levels were significantly decreased compared with levels before beta-adrenergic blockade (p less than 0.0002). Thus, plasma norepinephrine levels do not distinguish patients with reproducible exercise-induced ventricular tachycardia from otherwise comparable patients. Propranolol is highly effective in abolishing this arrhythmia and this effect is associated with decreased norepinephrine levels.

Adult↗
PubMed1986

Utility of ambulatory electrocardiographic monitoring for predicting recurrence of sustained ventricular tachyarrhythmias in patients receiving amiodarone.

The prognostic implications of changes in ventricular ectopic activity on serial 24 hour ambulatory electrocardiographic (Holter) recordings were prospectively evaluated in 107 patients with a history of sustained ventricular tachyarrhythmias treated with amiodarone for at least 30 days. Twenty-seven patients (25%) had insufficient ventricular ectopic activity (less than 10 ventricular premature complexes/h and no repetitive forms) on baseline Holter recordings for serial statistical analysis. In 53 (66%) of the remaining 80 patients, serial 24 hour Holter monitor recordings showed efficacy of treatment, defined as a 75% decrease in ventricular premature complexes, a 95% decrease in ventricular couplets and absence of ventricular tachycardia. During a mean follow-up period of 14.2 +/- 9.9 months, 34 (32%) of the 107 patients had recurrence of a sustained ventricular tachyarrhythmia. Holter recording correctly predicted nine recurrences and correctly identified 37 patients who did not experience a recurrence. Holter efficacy failed to predict recurrence of a sustained ventricular tachyarrhythmia in 16 patients, and 18 patients remained free of recurrence despite failure to achieve Holter efficacy. The positive predictive value of Holter monitoring efficacy was 33% and the negative predictive value was 70%; however, these differences were not statistically significant by chi-square analysis. Similar results were obtained using Holter recordings performed relatively early in therapy (6 weeks and 4 months). Of the 27 patients without significant ventricular ectopic activity on the baseline Holter recording, 9 had an arrhythmia recurrence despite continued infrequent ventricular premature complexes and no repetitive forms on subsequent recordings. The recurrence rate in this group (33%) was similar to the overall recurrence rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1986

Ultrafiltration in the management of refractory congestive heart failure.

Ultrafiltration was performed in nine patients with congestive cardiac failure that was refractory to conventional medical treatment. A mean of 12 X 7 litres of fluid was removed, and there was a sustained symptomatic improvement in all patients. Weight loss continued after ultrafiltration and a sustained increase in serum sodium concentration was also noted. A transient fall in right atrial pressure was seen only at four hours after ultrafiltration. No adverse haemodynamic effects were seen four and eighteen hours after fluid removal. Intracardiac dimensions measured by echocardiography remained unchanged. Ultrafiltration can be used to relieve symptoms in patients with refractory congestive heart failure and gross oedema.

Blood Pressure↗
PubMed1986

Proarrhythmic responses during electrophysiologic testing.

Proarrhythmia is a potentially lethal adverse effect of antiarrhythmic drugs. Underlying mechanisms and the approaches to identification are discussed. The applicability of electrophysiologic testing is considered, with particular reference to the validity of the different responses to programmed stimulation considered to be manifestations of proarrhythmia. The incidence of proarrhythmia in relation to individual antiarrhythmic agents is also reviewed.

Anti-Arrhythmia Agents↗
PubMed1985

Efficacy of combination therapy with mexiletine and a type IA agent for inducible ventricular tachyarrhythmias secondary to coronary artery disease.

The efficacy of combination therapy using a type IA agent (quinidine or procainamide) and a type IB agent (mexiletine) in suppressing inducible sustained ventricular tachyarrhythmias was studied in 23 patients undergoing serial drug testing with programmed stimulation. All patients had coronary artery disease (CAD) with previous myocardial infarction and abnormal left ventricular function (mean ejection fraction 35%). Fifty-five percent of the patients presented with syncope or cardiac arrest. In 19 patients therapy had failed during empiric trials of 1 to 3 antiarrhythmic agents. All 23 patients had inducible sustained ventricular tachyarrhythmias (18 had uniform morphology sustained ventricular tachycardia (VT) and 5 had ventricular fibrillation [VF]) during control electrophysiologic study, and therapy had failed with a type IA agent and mexiletine alone. The combination therapy of mexiletine and the type IA agent prevented induction of any ventricular tachyarrhythmias in 8 of 23 patients. In 15 patients, the combination significantly prolonged the tachycardia cycle length and reduced the symptoms associated with the induced arrhythmia. Patients more likely to respond to the combination had shorter cycle lengths and polymorphic configuration of the control-induced arrhythmia. The increased efficacy of the combination therapy could not be attributed to higher plasma drug levels for the combination, as there was no significant difference in plasma levels for each drug when given alone or in combination. Thus, the increased efficacy most likely reflects a synergistic electropharmacologic effect of the 2 agents.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Antiarrhythmic drug efficacy for ventricular tachyarrhythmias associated with coronary artery disease as assessed by electrophysiologic studies.

The efficacy and proarrhythmic potential of antiarrhythmic agents were evaluated. Programmed ventricular stimulation was performed in 160 consecutive patients with coronary artery disease during a baseline study and 432 subsequent drug studies. The tachyarrhythmias induced during baseline studies were sustained ventricular tachycardia (121 patients), ventricular fibrillation (16 patients), and symptomatic nonsustained ventricular tachycardia (23 patients). Regimens were completely successful if fewer than 6 repetitive ventricular responses were inducible during therapy and partially successful if no more than 15 repetitive ventricular responses were inducible. Procainamide and quinidine were the most successful single agents, with overall success rates of 24% and 35%, respectively. Either procainamide or quinidine combined with mexiletine was the most successful combination (overall success of 23%). Each anti-arrhythmic regimen showed a proarrhythmic potential. The incidence of proarrhythmic effects ranged from 4 to 13%, with no significant difference between regimens. In 13% of patients at least 1 regimen produced a proarrhythmic effect. Patients treated with an antiarrhythmic regimen that prevented induction of arrhythmia had significantly fewer arrhythmia recurrences than patients treated with a regimen that failed to prevent it. In conclusion, identification of an effective drug regimen is possible in 38% of patients with lethal ventricular arrhythmias, proarrhythmic effects occur in a significant number of patients during electrophysiologic testing of antiarrhythmic regimens, and the clinical outcome in patients in whom ventricular arrhythmias are not inducible with ventricular stimulation have a better prognosis than those in whom arrhythmias continue to be inducible on therapy.

Adult↗
PubMed1985

Usefulness of electrophysiologic testing in evaluation of amiodarone therapy for sustained ventricular tachyarrhythmias associated with coronary heart disease.

The prognostic importance of electrophysiologic studies in patients with sustained ventricular tachyarrhythmias treated with amiodarone was prospectively studied in 100 consecutive patients. Sustained ventricular tachycardia (VT)/ventricular fibrillation (VF) was inducible in all patients before amiodarone therapy. After amiodarone administration 2 groups of patients were identified. In group 1 patients the ventricular tachyarrhythmia was no longer inducible and in group 2 patients the arrhythmia remained inducible. In group 1, no recurrent arrhythmia occurred during a follow-up of 18 +/- 10 months. In group 2, 38 of 80 patients (48%) had arrhythmia recurrence during a follow-up of 12 +/- 9 months. The difference between group 1 and 2 could not be explained by clinical variables, amiodarone doses or plasma concentrations, or electrocardiographic variables. In patients in whom cardiovascular collapse or other severe symptoms where noted during electrophysiologic study after amiodarone treatment, recurrences caused sudden death (n = 12). However, in patients in whom the induced arrhythmia produced moderate symptoms, the recurrent arrhythmia was nonfatal VT (n = 26). Electrophysiologic testing provides clinical guidance and predicts prognosis in patients treated with amiodarone as it does for the evaluation of other antiarrhythmic agents.

Adult↗
PubMed1985

Limitations of failure of procainamide during electrophysiologic testing to predict response to other medical therapy.

To determine whether failure of procainamide to prevent initiation of ventricular tachyarrhythmias during electrophysiologic testing predicted failure of other antiarrhythmic regimens, 81 consecutive patients with coronary artery disease whose ventricular tachyarrhythmias remained inducible during procainamide administration were studied. Overall, 26 (12%) of 216 subsequent drug studies were successful and at least one effective drug regimen was identified in 22 (27%) of the 81 patients. Drug success was significantly related to the arrhythmia induced at baseline study; 7% of drug studies were successful in patients with sustained ventricular tachycardia, 24% in patients with ventricular fibrillation, and 29% in patients with nonsustained ventricular tachycardia. An effective drug regimen was found in 11 (19%) of 59 patients with sustained ventricular tachycardia, 4 (50%) of 8 patients with ventricular fibrillation and 7 (50%) of 14 patients with nonsustained ventricular tachycardia. In patients with sustained ventricular tachycardia, failure of procainamide to suppress the arrhythmia correlated with failure of other agents used singly but not in combination. This study supports the view that when procainamide fails to prevent initiation of the arrhythmia in patients with inducible sustained ventricular tachycardia it is unlikely that other individual standard agents will be effective. However, combination regimens may suppress the arrhythmia and should be evaluated. In patients with nonsustained ventricular tachycardia, all agents should be evaluated because failure to respond to procainamide does not predict subsequent responses to other agents either alone or in combination.

Adult↗
PubMed1985

Electrophysiologic testing in patients at high risk for sudden cardiac death. I. Nonsustained ventricular tachycardia and abnormal ventricular function.

Nonsustained ventricular tachycardia, although usually asymptomatic, is associated with a high risk of sudden cardiac death in patients with depressed left ventricular function. To test the vulnerability of such patients to symptomatic and potentially life-threatening arrhythmias, complete electrophysiologic studies were performed in 58 patients with clinically documented nonsustained ventricular tachycardia (greater than or equal to three complexes but less than 15 seconds of self-terminating ventricular tachycardia by 24 hour ambulatory electrocardiographic [Holter] or telemetric monitoring) and abnormal left ventricular function (ejection fraction less than 50% by radionuclide angiography). All patients had nonsustained ventricular tachycardia in the absence of antiarrhythmic drugs, acute ischemia, long QT syndrome, recent infarction or electrolyte abnormalities. The stimulation protocol for each patient included the introduction of single, double and triple ventricular extrastimuli at three cycle lengths (sinus, 600 and 450 ms) and two right ventricular sites (apex and outflow tract). A sustained ventricular tachyarrhythmia was induced in 23 patients (40%) and a nonsustained ventricular tachycardia in 14 patients (24%). Induction of sustained tachycardia correlated with the presence of akinesia or aneurysm, or both, by radionuclide angiography, but not with ejection fraction or presence or absence of coronary artery disease. These results indicate that: 1) patients with clinical nonsustained ventricular tachycardia and chronic left ventricular dysfunction have a high incidence of inducible sustained ventricular tachycardia or ventricular fibrillation; and 2) electrophysiologic testing may allow further substratification of risk of sudden cardiac death in high risk patients with nonsustained ventricular tachycardia.

Adult↗
PubMed1985

Comparative clinical efficacy of bepridil, propranolol and placebo in patients with chronic stable angina.

A randomised double-blind parallel group study was performed to compare the clinical efficacy of bepridil, a new calcium slow channel blocker, with that of propranolol and placebo in patients with chronic stable angina of effort. Efficacy was assessed objectively by dynamic exercise testing using an upright bicycle ergometer and subjectively by patient documentation of anginal frequency and nitrate consumption. The administration of bepridil resulted in a significant improvement in physical work capacity expressed as calculated maximal oxygen uptake (Vo2 max) and exercise time. This was associated with subjective improvement in terms of reduced anginal frequency. Despite baseline differences in exercise performance and anginal frequency between the three treatment groups, the beneficial effects of bepridil were statistically significant when compared to propranolol. Although minor electrocardiographic changes were noted, no adverse effects were evident when bepridil was prescribed in doses of up to 400 mg/day over a 10 week period.

Adult↗
PubMed1985

Electrophysiological effects of felodipine in combination with metoprolol.

The combined use of some beta-adrenoceptor blocking agents with calcium channel blockers may cause adverse pharmacodynamic drug interactions: hypotension, heart block or even asystole may be precipitated. The electrophysiological effects of combined administration of intravenous metoprolol 10mg and the vasodilating calcium antagonist felodipine (0.1 mg/kg/bodyweight) were assessed in an open study by invasive methods. Following metoprolol, the heart rate was reduced from 69 +/- 24 to 60 +/- 16 beats/min (mean +/- SD, p less than 0.05) with a minor prolongation of the sinus node recovery time. The A-H interval was increased from 94 +/- 25 to 109 +/- 16 msec (p less than 0.005) and the H-V interval was unchanged. The effective refractory period of the atrioventricular node was prolonged from 327 +/- 54 to 361 +/- 62 msec (p less than 0.01) with a minor prolongation of the effective refractory period of the ventricular Purkinje fibres. Systolic and diastolic blood pressures showed a mean reduction of 11 (p less than 0.001) and 6mm Hg (p less than 0.05), respectively. Following felodipine, the changes in heart rate and effective refractory periods of the atrioventricular node and ventricular Purkinje fibres returned towards control values. No further prolongation of the A-H interval resulted and further blood pressure changes were minor. The absence of adverse haemodynamic or electrophysiological effects suggests that this combination of agents may be safely used.

Adult↗
PubMed1985

Supraventricular tachyarrhythmias: atrial flutter and atrial fibrillation.

Symptoms range from mild palpitations to overt cardiac failure and cardiogenic shock, depending on the ventricular rate and the patient's underlying cardiac status. Drug therapy is the mainstay treatment. In atrial fibrillation, digoxin is used to control the ventricular response and therefore improve cardiac function. Verapamil may also be used for this purpose.

Aged↗
PubMed1984

Cardiac arrhythmias during rewarming of patients with accidental hypothermia.

Accidental hypothermia has a high mortality and is associated with cardiac arrhythmias. To determine the incidence of arrhythmias and their importance 22 patients with accidental hypothermia (core temperature less than 35 degrees C) were studied by 12 lead electrocardiography and continuous recording of cardiac rhythm. Although 14 of the patients died (64%), only six died while hypothermic. Prolongation of the Q-T interval and the presence of J waves were related to the severity of the hypothermia. Supraventricular arrhythmias, including atrial fibrillation, were common (nine cases) and benign. Ventricular extrasystoles were also common (10 cases), but ventricular tachycardia or fibrillation did not occur during rewarming. In eight patients who died while being monitored the terminal rhythm was asystole. There was no correlation between the severity of hypothermia or the rate of rewarming and the clinical outcome. In the absence of malignant arrhythmias there is no indication for using prophylactic antiarrhythmic treatment in patients with accidental hypothermia. The presence or absence of severe underlying disease is the main determinant of prognosis.

Adult↗
PubMed1984

Acylated streptokinase--plasminogen complex in patients with acute myocardial infarction.

BRL 26921 is the p- anisoyl derivative of the primary streptokinase-human plasminogen complex in which the acyl group is specifically located at the catalytic centre of the enzyme. Doses of BRL 26921 ranging from 5 mg to 25 mg were given intravenously or into a coronary artery to 12 patients with acute myocardial infarction. The complex was well tolerated and produced no serious bleeding. Coronary artery reperfusion was demonstrated angiographically in three patients. In most patients, fibrinogen, plasminogen, alpha 2 antiplasmin and alpha 2 macroglobulin levels fell and the level of fibrinogen degradation products increased acutely post treatment indicating systemic fibrinolytic activation. The degree of this activation was variable but was profound in some. It appeared to be dose related and modified by the presence of streptokinase antibodies. BRL 26921 appears less "selectively" thrombolytic in patients than had been expected from animal models.

Adult↗