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Biomedical subjects

L S Ong

Publications and source records attributed to L S Ong.

10 recordsLinked to original sources
PubMed1979

Familial cardiac myxoma: emphasis on unusual clinical manifestations.

This report describes familial cardiac myxoma involving parent and child. The familial occurrence of this condition, previously reported in four other families, underscores the necessity of screening all direct members of the family by echocardiography once the diagnosis of cardiac myxoma is made. Each patient presented with unusual clinical manifestations. The father, who had a right atrial myxoma associated with an atrial septal defect and mitral valve prolapse, presented with findings highly suggestive of paradoxical embolism. The daughter, who had an infected right ventricular myxoma, was initially treated for valvular subacute bacterial endocarditis before the diagnosis was made.

Adult↗
PubMed1978

Inapparent double puncture of the femoral artery and vein. An important complication of temporary cardiac pacing by the transfemoral approach.

An important complication of temporary cardiac pacing by the transfemoral approach. This report describes three cases of inapparent double puncture of the femoral artery and vein as a complication of the transfemoral approach for temporary cardiac pacing. This complication may lead to the passage of a pacing catheter to the right ventricle by way of the femoral artery and vein and may remain undiagnosed until the rigid outer sheath of the introducer set is withdrawn over the pacing catheter. Therefore, we recommend immediate withdrawal of the rigid outer sheath as soon as the catheter lies freely in the iliac vein or the inferior vena cava. If double puncture has occurred, arterial blood will leak around the pacing catheter. Control of arterial bleeding by local compression should not be attempted without removal of the pacing catheter.

Cardiac Pacing, Artificial↗
PubMed1978

The noise sampling period: a new cause of apparent sensing malfunction of demand pacemakers.

Two patients with Omni-Stanicor pulse generators presented an apparent sensing problem characterized by intermittent reversion to fixed-rate pacing only during atrial fibrillation with a very rapid ventricular rate. Every fixed-rate cycle contained two unsensed beats. The first unsensed beat fell in the noise sampling period (the last 1/6 of the pacemaker refractory period) and, therefore, disabled the demand function of the pulse generator for a single timing cycle. The presence of two consecutively unsensed beats within one timing cycle (automatic or escape interval) during tachycardia suggests normal function of the noise sampling period of this particular pulse generator, rather than a true sensing problem. The diagnosis becomes evident if the sensing problem disappears when abbreviation of the refractory period occurs by reprogramming the pulse generator at a higher rate.

Aged↗
PubMed1978

Unusual complication of bifascicular block during surgery under general anesthesia.

This report describes the occurrence of Mobitz type II AV block during surgery under general anesthesia in a patient with apparently uncomplicated right bundle branch and left anterior fascicular block (RBBB and LAH). Although prophylactic pacing is not usually recommended in uncomplicated RBBB and LAH, the events in this case suggest that this abnormality may not always be benign during surgery. Continuous monitoring is essential and emergency equipment for temporary pacing should be readily available near the operating and recovery rooms.

Aged↗
PubMed1978

Periodic pacemaker spike attenuation with preservation of capture: an unusual electrocardiographic manifestation of partial pacing electrode fracture.

This report describes the electrocardiograms of a patient with an intermittent electrode fracture presenting with periodic attenuation of the pacemaker spike without loss of ventricular capture. There was infrequent prolongation of the spike-to-spike interval probably because the pulse generator interpreted random false signals as interference and reverted to its fixed-rate mode. These observations add to the spectrum of electrocardiographic abnormalities of electrode malfunction.

Aged↗
PubMed1978

Reprogramming of implanted pacemaker following external defibrillation.

This report describes reprogramming of a pulse generator consequent to cardiac defibrillation. Analysis of the explanted pulse generator revealed normal function. We tested the electrical properties of several defibrillators and our studies suggest that erratic electrostatic discharges at the time of paddle application before defibrillation may create a signal sequence capable of reprogramming the particular pulse generator by activating either the reed switch or internal electronics.

Electric Countershock↗
PubMed1977

Inhibition of bipolar demand pacemaker by diaphragmatic myopotentials.

This report describes inhibition of a normally functioning bipolar demand pulse generator by diaphragmatic myopotentials. Transient pacemaker suppression occurred repeatedly with deep respiration, straining, the Valsalva maneuver, coughing, sneezing and laughing. When the magnet was applied, none of these maneuvers inhibited the pacemaker. Extensive investigations ruled out an intermittent electrode problem such as a wire fracture or insulation break. Sensing of diaphragmatic myopotentials should be considered in the differential diagnosis of unexplained pacemaker pauses.

Action Potentials↗