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Biomedical subjects

D Avgoustakis

Publications and source records attributed to D Avgoustakis.

At least 19 recordsLinked to original sources
PubMed1985

Inhibition of demand pacemakers by myopotentials.

The inhibition of unipolar demand pacemakers by myopotentials was studied in 215 paced patients with or without symptoms and in steady pacing rhythm. ECG recordings were taken of all patients at rest and during effort in which maximal muscular strength from the pectoralis major (PM) and rectus abdominis (RA) muscles was required. In 75 patients (34.9%) transient pacing inhibition was observed. In these patients myopotentials from the PM and RA muscles were recorded simultaneously at rest and during special effort. The PM was the dominant source of inhibiting myopotentials in 50.7% of the total patients with oversensing and the RA was dominant in 28%. In the remaining 21.3%, neither of these muscle groups alone was able to cause inhibition and a clear synergy of both the PM and RA muscles was required. When oversensing occurred in a pacemaker implanted in the thoracic wall, the PM was the dominant cause in 54.4% of patients and the RA in 23.5%, while a synergy of both muscles was required in the remaining 22%. When the pacemaker was implanted in the abdominal wall, the RA was the dominant source of inhibiting myopotentials in all but two patients.

Abdominal Muscles↗
PubMed1984

Cardiac arrhythmias in chronic renal failure? Holter monitoring during dialysis and everyday activity at home.

25 patients undergoing regular haemodialysis for chronic renal failure underwent Holter ECG monitoring for a continuous 48-hour period covering dialysis and the intermediate period of everyday activity at home. A low dialysate potassium concentration (1.7 mEq/l) was used. Clinically significant arrhythmias (greater than 100 ventricular extrasystoles/24 h) were found in only 1 patient and there were no complex ventricular arrhythmias. Benign atrial arrhythmias occurred in 22 patients (88%). Haemodialysis had no influence on type or frequency of arrhythmias.

Adolescent↗
PubMed1983

Rectus abdominis as a source of myopotentials inhibiting demand pacemakers.

We examined four patients with a demand pacemaker who exhibited transient symptoms of vertigo while trying to rise from the supine position. In two of these there was an epicardial pacing system with the pacemaker in the abdominal wall superficial to the rectus abdominis muscle; in the other two cases the pacing system was transvenous with the pacemaker superficial to the right pectoralis major muscle. It was found that the "pseudovertigo" was due to pacemaker inhibition caused by rectus abdominis myopotentials in all four patients. Changing the pacing mode from the demand to fixed-rate resulted in the disappearance of all symptoms at rest and during exercise.

Abdominal Muscles↗
PubMed1983

The importance of the sinus node artery in the blood supply of the atrial myocardium. An anatomical study of 360 cases.

The sinus node artery (SNA) and its contribution to the blood supply of the atrial myocardium (AM) were studied using X-rays and corrosion casting in a series of 360 human hearts. In 68 cases (19%) the SNA supplied the right atrium and part of the atrial septum (group A), in 211 cases (59%) it supplied the myocardium of one atrium (right or left), the atrial septum and part of the other atrium (group B), and in 81 cases (22%) the SNA supplied almost the entire AM (group C). In 133 cases (37%) the vessel supplying the sinus node (SN) was not the main continuation of the SNA, contrary to what is generally accepted. The SNA has many intercoronary and intracoronary anastomoses which comprise an important anastomosing net between the right coronary (RC) and left circumflex (LCir) arteries. These findings suggest that the SNA plays a major role in the blood supply of the AM apart from the SN.

Coronary Circulation↗
PubMed1981

False echocardiographic diagnosis of aortic root dissection in case of abdominal aortic dissection.

A patient with strong clinical and radiological indications of dissection involving the ascending aorta had this "confirmed" on an echocardiogram which showed a typical pattern of double lumen. At necropsy there was dissection of the abdominal aorta but the heavily calcified thoracic aorta was free of dissection. Echocardiography may be useful but not entirely reliable in the diagnosis of dissection even in the presence of a typical clinical picture.

Aged↗
PubMed1980

Double diastolic murmur in mitral stenosis with atrial fibrillation and complete heart block.

A double diastolic murmur was heard in a patient with mitral stenosis, atrial fibrillation, and complete heart block. Echo-phonocardiographic examination showed two separate opening and closing movements of the mitral valve in the same long diastole. A clear time relation was observed between the valve closing movements and the separate diastolic murmurs, giving support to the theory that the backward motion of the mitral valve against the forward blood flow through the valve is responsible for the production of these murmurs.

Atrial Fibrillation↗
PubMed1980

An S-shaped atrial artery supplying the sinus node area. An anatomical study.

An S-shaped sinus node artery (SSNA), originating in the posterolateral part of the left circumflex artery (LCir) below or behind the left auricle, is described in detail. The coronary vessels were studied in 300 human hearts by x-ray films or by casting of the vessels, and the SSNA was found in 24 (21.5 percent) of the 111 cases where the sinus node artery (SNA) arose from the LCir, (ie, 8 percent of all the hearts). The SSNA constituted a branch of the LCir in 15 cases, the upper part of a divided LCir in 6 cases, and the main continuation of this artery in 3 cases, always following basically the same route to the sinus node (SN) area. It was larger than the normal SNA, supplying the SN and surrounding area, almost the whole left atrium, a large part of the interatrial septum and right atrium, and partially supplying the atrioventricular node area.

Adult↗
PubMed1979

Early diastole in mitral valve disease.

Noninvasive findings from the study of early diastole in patients with mitral stenosis or mitral regurgitation are reported. Isovolumic relaxation time and the opening phase of the mitral valve are the main subintervals of early diastole. In mitral stenosis, a 3rd subinterval, the ECHO X-E phase, is described. Also, the effect of the cardiac cycle length on these intervals is studied, as well as the relationship between the opening snap, the O point of the apexcardiogram and the mitral echographic curve in early diastole.

Adolescent↗
PubMed1978

Effects of oxyfedrin: a beta-adrenoreceptor stimulant, on infarct size following acute coronary artery ligation.

Regional left ventricular blood flow and the extent of myocardial ischaemia were studied after acute coronary artery occlusion in open-chest dogs before and after infusion of oxyfedrin, a beta-adrenergic stimulant. Regional blood flow was measured with radioactive tracer microspheres and local tissue injury was estimated by the S-T segment elevation in epicardial electrocardiograms. Animals receiving oxyfedrin were divided into two groups: 1 and 2. Oxyfedrin was infused intravenously in a dose of 0.80 to 0.94 mg.kg-1 in dogs of group 1 and 1.45 to 1.60 mg.kg-1 in dogs of group 2. The rate of infusion in the animals of both groups was 0.61 mg.min-1. Oxyfedrin caused further S-T segment elevation over ischaemic myocardium and increased the extent of ischaemic injury in group 1 dogs. Conversely, in this same group of dogs, the blood flow was unchanged in low flow regions ( less than 0.3 cm3.g-1.min-1) and increased in higher flow areas, inside the ischaemic region. In the animals of group 2, oxyfedrin caused further S-T segment elevation over ischaemic myocardium and increased the extent of ischaemic injury. Concomitantly, blood flow was significantly reduced both inside and outside the ischaemic region. These observations in dogs of group 1 (ie increased blood flow inside the ischaemic region by infusion of oxyfedrin, in flow zones higher than 0.3 cm3.g-1.min-1, with a further S-T segment elevation over ischaemic myocardium, and an increase in the extent of ischaemic injury) may be explained by a primary effect of oxyfedrin on oxygen demands with secondary changes in blood flow.

Animals↗
PubMed1978

Noninvasive study of early diastole in mitral stenosis.

Cardiac events of early diastole were studied in 50 normal subjects and 46 patients with mitral stenosis (MS) by simultaneous recordings of the mitral valve echogram (MVE), phonocardiogram, and apexcardiogram (ACG). Left ventricular isovolumic relaxation time (IRT), measured between A2 and onset of the MVE opening motion, had almost the same values in normals 54 +/- 7 msec, and MS 51 +/- 16 msec. The interval between A2 and the ACG "O" point was approximately double that of IRT: 99 +/- 11 msec in normal subjects, 109 +/- 20 msec in MS. The normal MVE opening motion had a velocity 293 +/- 76 mm/sec and duration 45 +/- 6 msec, values significantly different (P less than 0.001) from 536 +/- 271 mm/sec, 23 +/- 7.5 msec found in MS patients. In atrial fibrillation the length of the cardiac cycle did not affect A2-O interval or mitral valve opening movement duration; however cycle length was clearly related to isovolumic relaxation time. This resulted in a variation in the interval between completion of the mitral valve opening (opening snap) and O point. This interval was longer after a short diastole and vice versa.

Adolescent↗
PubMed1978

Extent of the inferior myocardial infarction assessed by the frontal plane of the vectorcardiogram.

A correlation was made between the vectorcardiographic changes and the peak value of the L.D.H. in the serum of 21 patients with acute inferior (diafragmatic) M.I. The following vectorcardiographic variables showed changes proportional to the increase in serum L.D.H. The correlation was found to be statistically significant. The direction of the 0.025 sec vector (r = 0.63, P less than 0.005). The duration of the initial superior forces of the QRS loop (r = 0.87, P less than 0.001). The maximal leftward deviation of the initial superior QRS loop forces (r = 0.65, P less than 0.005). The maximal superior deviation of the initial QRS loop forces (r = 0.68, P less than 0.05). The ratio of the maximal superior deviation over the maximal inferior deviation of the QRS loop "QY/RY" (r = 0.76, P less than 0.001). The area under the initial superior forces of the QRS loop and over 0 degrees +/- 180 degrees axis in squared milimeters (r = 0.88, P less than 0.001). It is suggested that V.C.G. is a usefull means in assessing the extent of inferior M.I.

Female↗
PubMed1977

End-diastolic amplitude of mitral valve echogram in mitral stenosis.

By using simultaneous recordings of the mitral valve echogram and apex cardiogram, the mitral echogram amplitude was measured at the onset of left ventricular isovolumic contraction (MAIC). Twenty normal subjects and 68 patients with a reduced diastolic closure rate in the mitral valve echogram were studied. Of these patients, 53 had mitral stenosis, 6 aortic valvar stenosis, and 9 hypertrophic obstructive cardiomyopathy. In the normal subjects the MAIC ranged between 2 and 4 mm, average 2-7 mm, in the patients with aortic valvar stenosis or hypertrophic obstructive cardiomyopathy between 2 and 4 mm, average 2-9 mm, and in the patients with mitral stenosis between 6 and 17 mm, average 11-3 mm. The DE/MAIC ratio, where DE represents the opening amplitude of the mitral valve in early diastole, was between 3-3 and 6-5, average 5-1, in normal subjects; in the patients with aortic stenosis or hypertrophic obstructive cardiomyopathy the DE/MAIC ratio was between 2-7 and 6-5, average 4-2, and in the patients with mitral stenosis between 0-7 and 1-5, average 1-1. An excellent correlation was found between the DE/MAIC ratio and mitral valve area in the patients with mitral stenosis (r = 0-84, P less than 0-01) while the correlation between the diastolic closure rate and valve area was less satisfactory (4 = 0-62, P less than 0-01). These findings suggest that in cases with a reduced diastolic closure rate for reasons other than mitral stenosis, error can be avoided by using the DE/MAIC ratio.

Adolescent↗
PubMed1977

Re-entry ectopic ventricular rhythm caused by artificial pacing.

Two cases with coupled ectopic ventricular rhythm associated with artificial pacing are presented. The premature ventricular beats appeared at a fixed distance from the R of the previous electrical stimulus complex and when pacing was stopped ventricular arrest occurred. This provides strong evidence that the ectopic ventricular beats were dependent on the electrical stimulus and therefore that they were produced by its re-entry. It was observed that the re-entry phenomenon occurred at low rates. This arrhythmia even persisted after the permanent pacing and was successfully suppressed by procainamide in both cases.

Aged↗
PubMed1977

Rocking motion of the right cardiac cavities in Ebstein's anomaly. A specific cineangiographic sign.

In 7 cases of Ebstein's anomaly the right cineangiogram disclosed a big right atrium, the tricuspid valve positioned to the left of the spine and tricuspid regurgitation. The right atrial appendage was nearing the outflow tract of the right ventricle and the pulmonary artery so as the normal U appearance of the right aniograms was abolished. In addition to these signs a very characteristics and almost pathognomonic rocking motion of the radiopaque material, moving from the right atrium towards the right ventricle during ventricular diastole and backwards to the atrium during the next ventricular systole was observed. This sequence of motion gives the impression of a rocking hammock or pendulum.

Angiocardiography↗