Search PubMed⌕ Search

Biomedical subjects

A W Nathan

Publications and source records attributed to A W Nathan.

At least 73 records · Page 4Linked to original sources
PubMed1983

Electrophysiological abnormalities in the transplanted human heart.

Fourteen relatively long term survivors of cardiac transplantation underwent systematic electrophysiological evaluation and ambulatory electrocardiographic monitoring. Six patients had prolonged conduction intervals during sinus rhythm. Sinus node function could be assessed in all donor atria and in 10 recipient atria. Sinus node recovery times were prolonged in four of the donor atria and in six recipient atria. In the donor atria abnormalities of sinus node automaticity were invariably associated with abnormalities of sinoatrial conduction. Four patients showed functional duality of atrioventricular nodal conduction during programmed extrastimulation, but no patient developed re-entrant arrhythmia. During ambulatory electrocardiographic monitoring no pronounced tachyarrhythmias were recorded. Three patients showed abnormalities of sinus node impulse formation. All three patients had abnormal sinus node recovery times during their electrophysiological study. Long term survivors of cardiac transplantation have a high incidence of electrophysiological abnormalities. Abnormalities of donor sinus node function are probably of clinical significance. The clinical significance of abnormalities detected within the atrioventricular conduction system of the denervated heart remains to be elucidated.

Adult↗
PubMed1983

The effects of plasma from patients with Graves' disease on foetal mouse hearts in organ culture.

Plasma, obtained during plasma exchange therapy, from 3 euthyroid patients with Graves' disease and severe progressive exophthalmos induced an increase in heart rate and then early death when applied to foetal mouse hearts maintained in isolated organ culture. All plasma samples which induced an increase in foetal heart rate had high titres of thyroid stimulating immunoglobulins. Plasma samples obtained after exchange had a much diminished effect. These studies may indicate a previously unrecognized non-thyroidal action of the abnormal immunoglobulins associated with Graves' disease and suggest that chronic thyroid heart disease may be due, at least in part, to the effect of these immunoglobulins especially when not associated with elevated thyroid hormones concentrations.

Animals↗
PubMed1983

Systemic lupus erythematosus and IgA deficiency.

A survey of 138 patients with systemic lupus erythematosus (SLE) (113 with nephritis) was carried out following the finding of a patient with membranous nephropathy and IgA deficiency who later developed SLE. Two hundred random hospital patients and 143 patients with idiopathic glomerulonephritis were also studied. One patient with minimal change nephrotic syndrome had IgA deficiency, but the other 342 patients had normal IgA concentrations. In the SLE group, in contrast, 4 patients had IgA deficiency and another patient prolonged IgA deficiency following phenytoin treatment. These and other published data suggest that the association of IgA deficiency is about 20 times more common in patients with SLE and nephritis than in the general population. This association may be a manifestation of defective T-cell regulation, a failure to eliminate immune complexes in the absence of IgA, or both.

Adolescent↗
PubMed1982

Initial experience with a fully implantable, programmable, scanning, extrastimulus pacemaker for tachycardia termination.

A fully implantable automatic scanning pacemaker designed for tachycardia termination has been used in three patients with regular paroxysmal supraventricular tachycardia. The pacemaker recognizes tachycardia and delivers one or two extrastimuli which automatically scan inwards if tachycardia continues. A memory is incorporated to retain and immediately reuse a successful pacing sequence if tachycardia recurs. Ventricular pacing has been used in two patients and atrial stimulation in one. Although all had suffered frequent attacks of tachycardia after implantation no sustained episodes of tachycardia have been appreciated. No unwanted arrhythmias have been induced and drug treatment has been stopped in all three patients. Fully implantable scanning pacemakers which automatically recognize and revert tachycardia offer an effective and versatile form of treatment of recurrent paroxysmal tachycardias.

Aged↗
PubMed1982

Implantable automatic scanning pacemaker for termination of supraventricular tachycardia.

Thirteen patients suffering from reentrant supraventricular tachycardia have undergone implantation of a scanning extrastimulus pacemaker. This pacemaker is fully implanted and automatic, and it requires no external control device to activate or control it. The pacemaker is activated when tachycardia occurs. After four cycles an extrastimulus is induced with a preset coupling time from a sensed intracardiac potential, and every four cycles thereafter a further extrastimulus occurs, but on each occasion there is a decrement in coupling cycle by 6 ms until 90 ms of the cardiac cycle has been scanned by extrastimuli. When necessary, two extrastimuli can be introduced with a fixed but preset coupling time between them. Every four beats two extrastimuli are induced but the coupling time between the spontaneous cardiac potential and the first stimulus is decreased by 6 ms until 90 ms of the cardiac cycle has been scanned. The coupling time between the two stimuli is fixed throughout the scan. When termination of tachycardia occurs the successful timing variables are retained in the pacemaker memory so that at the onset of the next episode of tachycardia these settings are used first. Pacemaker pulse width, sensitivity, tachycardia trigger rate, coupling intervals for both stimuli and the use of single or double extrastimuli are all programmable transcutaneously. Three patients required single, and seven patients double ventricular premature stimuli; three patients required double atrial premature stimuli for termination of tachycardia. Despite frequent attacks of tachycardia before implantation, only two patients had a sustained attack of tachycardia after pacemaker implantation.

Adolescent↗
PubMed1982

Differential response to carotid sinus pressure during sinus rhythm and atrial fibrillation.

In a patient who presented with syncope and palpitation left carotid sinus massage resulted in prolonged ventricular asystole during atrial fibrillation. In the same patient left carotid sinus stimulation during sinus rhythm produced no change in sinus rate and only slight PR interval prolongation. This very different response may be the result of factors which are relevant only during atrial fibrillation such as an increase in the atrial depolarisation frequency and a prolongation of the duration of the atrioventricular nodal concealment zone secondary to increased vagal activity. An increase in atrioventricular nodal refractoriness could not explain this differential response.

Aged↗
PubMed1982

Electrophysiological effects of sotalol--just another beta blocker?

The electrophysiological effects of intravenous sotalol hydrochloride (0.4 mg/kg) were assessed in 24 patients, including 13 with the Wolff-Parkinson-White syndrome, undergoing routine electrophysiological study. Fifteen to 30 minutes after sotalol administration there was a significant increase in sinus cycle length and in sinus node recovery time. There was a small increase in the AH interval, but the HV interval was unchanged. The QT and JT intervals, measured during sinus rhythm, were both increased. The atrial, ventricular, and atrioventricular nodal effective refractory periods were all prolonged, as was the atrioventricular nodal functional refractory period. In 13 patients with ventricular pre-excitation there was an increase of the accessory pathway anterograde and retrograde effective refractory periods. In 12 of these 13 sotalol was given during atrioventricular re-entrant tachycardia, resulting in termination in five. Tachycardia cycle length increased in all patients, with the major effect being in the atrioventricular direction. Though some of the effects seen in these patients are consistent with the beta adrenergic antagonist properties of sotalol, the effect on atrial, ventricular, and accessory pathway effective refractory periods and on ventricular repolarisation is not typical of that observed with other beta blockers but may be the result of lengthening of the action potential duration. These findings suggest that sotalol may be a more versatile antiarrhythmic agent than other beta receptor antagonists.

Adolescent↗
PubMed1982

Acute electrophysiological effects of flecainide acetate on cardiac conduction and refractoriness in man.

The electrophysiological effects of flecainide acetate (2 mg/kg as an intravenous infusion over five minutes) were assessed in 47 patients undergoing electrophysiological study. Seven patients had normal electrophysiology, 16 had a direct accessory atrioventricular pathway, 12 had dual atrioventricular nodal (AH) pathways, five had paroxysmal ventricular tachycardia, six had conduction system disease, and one patient had a left atrial tachycardia. No significant change occurred in sinus cycle length. The PA interval, AH interval, and HV interval were all significantly prolonged. The QRS complex duration increased significantly. The QT interval showed slight prolongation due entirely to the increase in QRS duration. Refractoriness of the atrial and ventricular myocardium was slightly prolonged, but was significant only at ventricular level. No significant change occurred in refractoriness of the normal atrioventricular node. Pronounced prolongation of retrograde "fast" AH pathway refractoriness was observed in those patients with dual AH pathways. Anterograde and retrograde accessory pathway refractoriness were both greatly increased. These electrophysiological properties strongly suggest that flecainide will be useful in the management of a wide variety of cardiac arrhythmias. It should be administered, however, with caution to patients with pre-existing conduction system disease. Because repolarization is not delayed flecainide is unlikely to induce ventricular arrhythmias related to prolongation of the QT interval.

Adolescent↗
PubMed1982

Hypercalcaemia due to immobilization of a patient with Paget's disease of bone.

A man with Paget's disease of bone was admitted with a fractured neck of femur. On admission he was normocalcaemic, but with immobilization he rapidly became hypercalcaemic, despite a normal diet and no medication. The hypercalcaemia responded to calcitonin. Although hypercalcaemia is often quoted as complicating the immobilization of such patients, well documented uncomplicated cases have rarely been reported.

Aged↗
PubMed1982

Corynebacterium hofmannii infection after renal transplantation.

A case of malakoplakia affecting the entire urinary tract is described. The patient had received a cadaveric renal transplant and had required particularly heavy immunosuppression because of recurrent rejection episodes. Heavy hematuria developed, and this was followed by obstruction at the vesico-ureteric junction. Despite adequate drainage via a nephrostomy, the graft ceased functioning, and was explanted. Although appropriate antibiotics were given, the patient died. The organism responsible for triggering the malakoplakia was Corynebacterium hofmannii, and this is only the third report of this organism as a human pathogen. However, other coryneform bacteria have been reported as being pathogenic in immunosuppressed subjects, and should be sought when more common organisms cannot be cultured in such patients showing signs of infection.

Adult↗