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Biomedical subjects

D Alexopoulos

Publications and source records attributed to D Alexopoulos.

52 records · Page 3Linked to original sources
PubMed1988

The 24-hour heart rate behavior in long-term survivors of cardiac transplantation.

A detailed computerized analysis of heart rate (HR) behavior during ambulatory monitoring was performed in 19 long-term survivors of cardiac transplantation (12 orthotopic, 7 heterotopic) and in 10 normal volunteers. Compared with normal hearts, the transplanted denervated and the recipient innervated hearts in the heterotopic group showed higher average HRs over the whole 24 hours, the waking and sleeping periods. The rates of the denervated and the recipient hearts did not differ significantly. The maximal HR was similar in all 3 groups, but the minimal HR was lower in the normal hearts than in denervated and recipient hearts. The 24-hour RR interval variability was greatly reduced in the denervated hearts (60 +/- 22 ms) compared with the recipient (89 +/- 26 ms) and normal (151 +/- 38 ms) hearts. During arousal from sleep, the magnitude, time and rate of the HR change were significantly reduced in the denervated hearts compared with the innervated hearts and in the recipient compared with the normal hearts. These findings demonstrate that denervated hearts can show significant variations in HR during the 24-hour period, but to a lesser extent than normal hearts. The widest deviation from normal occurs during sleep, when the denervated heart shows minimal slowing probably due to lack of parasympathetic innervation. In heterotopic transplant recipients, the patients' own HR responses also are significantly blunted.

Adult↗
PubMed1988

Angiographic progression of coronary artery disease and the development of myocardial infarction.

There are few data on angiographic coronary artery anatomy in patients whose coronary artery disease progresses to myocardial infarction. In this retrospective analysis, progression of coronary artery disease between two cardiac catheterization procedures is described in 38 patients: 23 patients (Group I) who had a myocardial infarction between the two studies and 15 patients (Group II) who presented with one or more new total occlusions at the second study without sustaining an intervening infarction. In Group I the median percent stenosis on the initial angiogram of the artery related to the infarct at restudy was significantly less than the median percent stenosis of lesions that subsequently were the site of a new total occlusion in Group II (48 versus 73.5%, p less than 0.05). In the infarct-related artery in Group I, only 5 (22%) of 23 lesions were initially greater than 70%, whereas in Group II, 11 (61%) of 18 lesions that progressed to total occlusion were initially greater than 70% (p less than 0.01). In Group I, patients who developed a Q wave infarction had less severe narrowing at initial angiography in the subsequent infarct-related artery (34%) than did patients who developed a non-Q wave infarction (80%) (p less than 0.05). Univariate and multivariate analysis of angiographic and clinical characteristics present at initial angiography in Group I revealed proximal lesion location as the only significant predictor of evolution of lesions greater than or equal to 50% to infarction. This retrospective study suggests that myocardial infarction frequently develops from previously nonsevere lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Serial pulmonary blood volume changes with supine exercise in normal subjects and in coronary artery disease patients.

Relative changes in pulmonary blood volume (PBV) were assessed serially at first stage, peak and post-supine exercise in 13 young normal volunteers and 33 coronary artery disease (CAD) patients. Gated blood pool imaging was used with time corrected count calculation of a region over the lung and comparison to the rest image. In normal subjects, the PBV ratio did not change with exercise but dropped significantly immediately post-exercise. In CAD patients, the PBV ratio increased in the first exercise stage, increased further at peak exercise, and fell significantly following exercise cessation. In the three stages studied, significantly higher PBV ratios were demonstrated in the CAD patients compared to normal subjects, but with significant overlap between the two groups. No significant relation was found between PBV changes and the number of diseased vessels, severity score (Gensini), left ventricular end-diastolic pressure, exercise-limiting symptoms, and left and right ventricular ejection fraction at rest and with exercise. Despite the different response of the PBV ratio to exercise between normals and CAD patients, a significant overlap limits the value of this ratio as a discriminator of the presence, severity or location of CAD.

Adult↗
PubMed1988

Supraventricular tachycardia after heterotopic heart transplantation.

Heterotopic cardiac transplantation where the recipient heart remains in tandem with the donor heart has a one-year survival of approximately 80%. Rhythm disturbances after heterotopic cardiac transplantation have rarely been described and their potential influence on the patients symptoms and prognosis is unclear. We report a case of supraventricular tachycardia of the recipient heart in a patient following heterotopic heart transplantation recorded during ambulatory electrocardiographic monitoring.

Electrocardiography↗
PubMed1988

Ventricular arrhythmias in long term survivors of orthotopic and heterotopic cardiac transplantation.

Fourteen long term survivors with orthotopic (recipient heart replaced by donor heart) and nine with heterotopic cardiac transplants (recipient heart retained) had 24 hour ambulatory electrocardiographic monitoring to detect ventricular arrhythmias. Arrhythmia was uncommon in the patients with orthotopic transplants; none of them had more than one extrasystole per hour. In the patients with heterotopic cardiac transplants the recipient's own heart showed significantly more frequent ventricular arrhythmias than the corresponding donor heart: abnormal complexes (mean/24 h) 4583 vs 42.7; extrasystoles 1772 vs 17.8; pairs 121 vs 0.8. There was no relation between the abnormal ventricular activity of the two hearts in the patients with heterotopic transplants on a beat by beat, hourly, or 24 hour basis. There was no consistent diurnal variation in the frequency of the abnormal ventricular beats after cardiac transplantation. The occurrence of ventricular arrhythmia was unrelated to the interval from operation to the study. In long term survivors of cardiac transplantation the denervated heart shows a little ventricular ectopic activity even when compared with normal hearts. In patients with heterotopic transplants ventricular arrhythmias commonly occur in the recipient's own heart; these are probably related to the underlying severity of the original disease.

Adult↗
PubMed1988

A comparison of the long-term effects of sotalol and atenolol on QT interval and arrhythmias after myocardial infarction.

In order to dissociate the Class III effects of sotalol on QT interval and arrhythmias from those of chronic beta-receptor blockade, we compared the effects of sotalol 160 mg b.d. and atenolol 50 mg b.d. in a double-blind crossover study of 103 patients followed for one year after discharge following acute myocardial infarction. Sotalol caused a highly significant lengthening of the absolute and corrected QT (QTc) interval over atenolol which was apparent by day 6 and persisted unchanged throughout the follow-up period. The increase in QT interval averaged 43 ms (9%). Sotalol blunted the increase in ventricular premature beat frequency on ambulatory monitoring which occurred with atenolol, although direct comparison of arrhythmia frequency between the groups receiving atenolol and sotalol revealed no significant difference. Marked lengthening of QTc interval (greater than 500 ms) was observed on 29 occasions in patients receiving sotalol, most commonly at day 6, but no episodes of polymorphic ventricular tachycardia were recorded. The Class III action of sotalol persists over and above any response to beta-blockade during a one-year follow-up period. In a population with a low incidence of spontaneous arrhythmias, however, there was only a modest difference in antiarrhythmic efficacy between atenolol and sotalol. Episodes of marked lengthening of QT interval induced by sotalol in the absence of other adverse factors need not be arrhythmogenic.

Adult↗
PubMed1986

Subsidiary class III effects of beta blockers? A comparison of atenolol, metoprolol, nadolol, oxprenolol and sotalol.

The electrophysiological effects of various concentrations of atenolol, metoprolol, nadolol, D-oxprenolol, L-oxprenolol, and D, L-oxprenolol and D-sotalol, L-sotalol, and D, L-sotalol were compared in rabbit right ventricular papillary muscle studied in vitro using intracellular microelectrodes. An assessment of the relative beta blocking effects of D-sotalol and D, L-sotalol against the inotropic action of isoprenaline was made in the same preparation. Of the drugs tested, only oxprenolol and sotalol showed prolongation of action potential duration and effective refractory period (class III action), with oxprenolol showing, in addition, depression of maximal upstroke velocity and the presence of post-repolarisation refractoriness (class I action). When contrasted at clinically relevant concentrations, only sotalol retained a class III effect, without any actions on variables related to fast inward current. The effects of oxprenolol and sotalol were not found to be stereospecific. The mechanical experiments indicate that, in this preparation, D-sotalol has approximately one-fourteenth of the beta blocking potency of the racemic compound. It therefore merits further consideration as a useful alternative class III antiarrhythmic agent, which would be free from the side effects of beta receptor blocking treatment.

Action Potentials↗
PubMed1986

Cardiac abnormalities in familial palmoplantar keratosis.

Cardiac abnormalities were identified in patients with familial palmoplantar keratosis. All of them were descended from families on the Greek island of Naxos. Four families were studied and nine cases of palmoplantar keratosis were identified; seven of them showed symptoms and signs of heart disease. Cardiomegaly on chest x ray and electrocardiographic abnormalities were common findings. Three cases had episodes of ventricular tachycardia and a fourth patient died suddenly. All patients with cardiac signs and symptoms showed echocardiographic enlargement of the right ventricle and a right ventricular band; in three the left ventricle was also affected.

Adolescent↗
PubMed1985

The influence of acute myocardial ischaemia on the class III antiarrhythmic action of sotalol.

The effects of acute myocardial ischaemia on the Class III antiarrhythmic properties of dl-sotalol 10(-4) mol . litre-1 were studied in the isolated arterially perfused interventricular septum of the rabbit heart. Before ischaemia, sotalol increased mean action potential duration (APD90) from 267 +/- 6 to 406 +/- 19 ms (p less than 0.001 mean +/- SEM, n = 7 septa), and mean effective refractory period (ERP) from 222 +/- 7 to 291 +/- 10 ms. During 30 min zero flow global ischaemia, mean APD90 in the control group fell from 264 +/- 7 to 128 +/- 13 ms (n = 7). APD90 fell more rapidly in the sotalol group, so that the initial difference between the sotalol and control groups was abolished after 24 min ischaemia. In the sotalol group, ERP shortened rapidly during ischaemia, and was significantly less than in the control group after 30 min. These changes were associated with the development of substantial post-repolarisation refractoriness in the control but not in the sotalol group. There was a greater fall in action potential upstroke velocity in the controls than in the sotalol group. The results indicate that the Class III effect of sotalol gradually disappears during ischaemia. The effects on post-repolarisation refractoriness and upstroke velocity are compatible with the hypothesis that sotalol slows the rate of rise of extracellular potassium concentration in acute ischaemia. This is a potentially antiarrhythmic property.

Action Potentials↗
PubMed1985

Interaction of the effects of hypoxia, substrate depletion, acidosis and hyperkalaemia on the class III antiarrhythmic properties of sotalol.

The effects of hypoxia on the actions of dl-sotalol 10(-4) mol . litre-1 were studied in rabbit papillary muscles at 32 degrees C. Superfusion for 30 min with a hypoxic solution (95% N2, 5% CO2) in the presence of 5 mmol . litre-1 glucose caused moderate shortening of control action potential duration from 208 +/- 3 to 138 +/- 9 ms (mean +/- SEM). In the presence of sotalol, hypoxia caused shortening of APD90 from 399 +/- 9 ms to 249 +/- ms, but the value after 30 min was still significantly greater than in controls (p less than 0.001). Superfusion with a hypoxic, glucose-free solution, however, caused profound shortening of APD90 in controls to 80 +/- 7 ms at 30 min. The highly significant lengthening of APD90 produced by sotalol in control conditions was abolished after 5 min hypoxia. The effects of hypoxia on the effective refractory period (ERP) paralleled those on APD90. Exposure to a hypoxic, acidotic, hyperkalaemic solution (80% N2, 20% CO2, pH 6.8; K+ 12 mmol . litre-1) produced moderate shortening of APD90 with convergence of the two groups. There was an increase in ERP, with the development of an equal degree of post-repolarisation refractoriness in the control and sotalol groups. The Class III effect of sotalol is preserved under mild but lost under severely hypoxic conditions. Using "simulated ischaemic" conditions, with controlled extracellular potassium concentrations, there was no difference in the relationship between APD90 and ERP in the control and sotalol groups.

Acidosis↗
PubMed1984

Serum sickness complicating intravenous streptokinase therapy in acute myocardial infarction.

A case of delayed serum sickness with transient renal impairment is described in a patient who received early high dose intravenous streptokinase following acute myocardial infarction. Review of the literature suggests that serum sickness after streptokinase may occur independently of the dose or route of administration, and could potentially complicate intracoronary streptokinase therapy.

Acute Kidney Injury↗
PubMedDate not supplied

Coronary arteriographic findings in symptomatic and asymptomatic subjects with coronary artery calcification.

The relation of coronary artery calcification with the presence of symptoms of coronary artery disease and its angiographic severity is not clear. We studied 37 apparently healthy, asymptomatic subjects that were found by digital cinefluoroscopy to have coronary calcium and compared to age- and sex-matched group of patients with coronary calcium and symptomatic coronary artery disease. Normal coronary arteries and non-obstructive lesions only were found in 12/37 (32.4%) and 11/37 (29.7%) asymptomatic subjects vs. 1/37 (2.7%) and 2/37 (5.4%) patients; P<0.001 and P<0.012, respectively. Obstructive lesions were more rare in asymptomatic subjects than in patients, 14/37 (37.8%) vs. 34/37 (91.9%) (P<0.0001), as well as total occlusions, 2/37 (5.4%) vs. 10/37 (27%) (P<0.024). Median worst lesion stenosis was 30% in asymptomatic subjects and 95% in patients (P<0.0001). In asymptomatic usual cardiovascular risk subjects, coronary calcium detection by digital cinefluoroscopy is accompanied by a relatively high probability of obstructive disease, although less severe angiographically than in age- and sex-matched catheterized patients with symptomatic coronary artery disease.

Aged↗