Biomedical subjects

A S Agha

Publications and source records attributed to A S Agha.

At least 19 recordsLinked to original sources

PubMed1979

Radiographic studies of upper airway obstruction with cor pulmonale in a patient with pycnodysostosis.

The purpose of this article is to present radiographic aspects of obstructive anatomical alterations of the upper airway before and during sleep in a 4 1/2-year-old boy affected with pycnodysostosis. The striking length of the uvula and the inspiration-exspiration changes in its position was an important factor in the obstruction of the upper airway. For better and earlier understanding of the actual mechanism of upper airway obstruction, the radiological data should be obtained during the same circumstances that the patient is experiencing his maximum discomfort.

Abnormalities, Multiple↗

PubMed1977

Evaluation of intracardiac recordings in diagnosis of impulse formation and concealed conduction in atrioventricular nodal bypass tracts.

Invasive electrophysiological studies were performed in 2 symptomatic patients with recurrent arrhythmias in which impulse formation presumably occured within atrioventricular nodal bypass tracts. Case 1 had ectopic beats arising within, or close to, the upper end of a left-sided atrioventricular nodal bypass tract of the type described by Brechenmacher. In addition, this conduction was 'concealed' during sinus rhythm and right atrial pacing because the relatively prolonged right-to-left atrial conduction time allowed right atrial impulses to reach the His bundle via the atrioventricular node before they could do so through the atrioventricular nodal bypass tract. Case 2 had ectopic beats arising in a right-sided atrioventricular nodal bypass tract which did not conduct in either forward or retrograde directions, its presence being detected only when initiating impulses. However, it could not be determined whether this tract was an 'abnormal' atrio-His connection or a 'normal' transitional (atrio-atrioventricular nodal) tract. Though intracardiac studies complement body surface recordings, they should be interpreted with knowledge of their inherent limitations.

Adult↗

PubMed1976

His bundle recordings in diagnosis of impulse formation in Kent and Mahaim tracts.

His bundle electrograms were recorded in 2 patients with ectopic beats arising in accessory atrioventricular tracts. Case 1 had Wolff-Parkinson-White (WPW) type A and a left-sided Kent tract with a short effective refractory period. Though ectopic impulse formation most probably occurred within the Kent tract itself, a vulnerability-related origin in the ventricular muscle close to the distal end of the Kent tract could not be excluded. In Case 2, with a Mahaim tract extending from His bundle to ventricles, there were three types of QRS morphologies resulting from : (a) atrioventricular conduction exclusively through the normal pathways; (b) atrioventricular conduction through both, normal pathway, and Mahaim tract; and (c) ectopic impulse formation in the Mahim tract. Specialized electrophysiological studies were essential to diagnose these unusual arrhythmias.

Adult↗

PubMed1976

Bipolar catheter electrograms for study of retrograde atrial activation pattern in patients without pre-excitation syndromes.

The sequence of retrograde atrial activation of premature ventricular beats was studied in 12 patients without pre-excitation syndrome. Forward and retrograde AV nodal conduction times were within normal limits. The septal low right atrial (LRA2) deflection was inscribed 25 to 55 ms (ave: 37.9 ms) before the low left atrial (LLA2) electrogram and 35 to 75 ms (ave: 53.7 ms) ahead of the high right atrial (HRA2) deflection. LLA2 preceded HRA2 in 8 patients, more or less coincided with HRA2 in 3 cases, and was inscribed 10 ms ahead in 1 patient. In all cases a decrease in the coupling (St1-St2) interval resulted in a proportional increase of the septal LRA1-LRA2, LLA1-LLA2, and HRA1-HRA2 intervals. Atrial echoes occurring in 3 cases had a sequence of arrival of excitation at the recording sites which was similar to the ones shown by the same patients during ventricular pacing. This is in keeping with the existence of an upper common pathway located above the area where functional longitudinal dissociation occurred. Thus, it is concluded that impulses emerging from the AV node in a retrograde direction reach the septal low right atrium before they activate the explored low left atrial sites, regardless as to whether they arise in the ventricles or in the atria.

Arrhythmias, Cardiac↗

PubMed1975

Etiology of the electrocardiographic pattern of "incomplete right bundle branch block" in atrial septal defect: an electrophysiologic study.

His bundle and right ventricular apical endocardial electrograms were recorded in 18 patients, ages five to 17 years, of whom ten had atrial septal defect of the secundum type and eight had mild aortic stenosis. The H-RVA interval was assumed to approximate conduction time from the level of the His bundle along the RBB to the site of earliest activation in the right ventricle at the RVA. The H-V interval was normal in all patients (less than or equal to 40 msec). All patients in the ASD group had an rsR' or rSr' pattern in Vl with a mean duration of 99 +/- 9 msec (86 to 116 msec); the mean duration of the H-RVA intervals was 54 +/- 6 msec in this group. In patients with AS, the surface electrocardiograms were normal, with a mean QRS duration of 82 +/- 8 msec (70 to 95 msec); the H-RVA intervals averaged 52 +/- 6 msec. The difference in the H-RVA intervals in the two groups was not statistically significant (P greater than 0.50) despite the fact that patients with ASD had significant prolongation of QRS duration (P greater than 0.001). Moreover, when functional RBB block was induced by premature atrial stimulation in the ASD group, the prolongation of QRS duration was accompanied by an increase in H-RVA interval, indicating relatively intact function of the RBB. It is concluded that the rsR' or rSr' pattern in ASD is likely to be a manifestation of right ventricular overload rather than a true conduction delay in the RBB.

Adolescent↗

PubMed1975

Measurements of conduction times with catheter electrodes during pacing from different ventricular sites.

Filtered bipolar catheter electodes, I mm apart, were used to pace and record from the high right atrium, right ventricular apex, right ventricular outflow tract, right ventricular inflow tract, middle cardiac vein, great cardiac vein, and endocardium of the left ventricular septal surface. Right ventricular apex to middle cardiac vein and the middle cardiac vein to right ventricular apex conduction intervals gave a rough estimate of anteroposterior and posteroanterior "transseptal plus free left ventricular wall" conduction times, respectively. On the other hand, the right ventricular apex to left ventricular septal surface and left ventricular septal surface to right ventricular apex intervals represented pure "transseptal" conduction times, since both sets of electrodes were in contact with the respective septal surface. During stimulation of the intermediately located right ventricular inflow tract propagation to the right ventricular apex and right ventricular outflow tract was longer than between these two sites. Moreover, conduction was almost as delayed to the right ventricular apex and right ventricular outflow tract as it was to the left ventricular septal surface. These findings were attributed to the peculiar electrophysiological behaviour of the right ventricular inflow tract muscle. Pacing from different segments of the great cardiac vein produced QRS morphologies and arrival of excitation patterns consistent with the relation between the anatomical location of this structure and the recording electrodes. However, from this study no inferences could be drawn regarding the conduction velocity or specific conduction pathways used by the stimulus in its journey from stimulating to recording areas.

Arrhythmias, Cardiac↗

PubMed1975

Double accessory pathways in Wolff-Parkinson-White syndrome.

Intracardiac electrophysiological studies were performed in two patients with Wolff-Parkinson-White (WPW) syndrome. Atrial pacing at increasing rates or shorter coupling intervals produced inscription of the forward His bundle deflection at progressively longer intervals after the onset of ventricular depolarization. There was an associated increase in QRS duration without any change in the P-R (or St-V) interval. This response was consistent with a Kent bundle. Case 1 also had a short A-H interval which did not show the expected prolongation with stimulation at progressively faster rates. This suggested the presence of a James bundle in addition to the Kent bundle. In case 2 beats conducted exclusively through the atrioventricular (A-V) node had a short H-V interval but a delta wave was not inscribed. Absence of an initial slurring was attributed to the existence of an infra-His bundle bypass of the Mahaim type causing only slight pre-excitation, which was not of sufficient magnitude to be recorded by body surface leads. However, the existence of a congenitally short anterosuperior division of the left bundle could nt be excluded.

Bundle of His↗

PubMed1973