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Biomedical subjects

V Parsonnet

Publications and source records attributed to V Parsonnet.

At least 199 records · Page 11Linked to original sources
PubMed1979

Method for the rapid and atraumatic insertion of permanent endocardial pacemaker electrodes through the subclavian vein.

One hundred sixty-four permanent pacemaker implantations through the subclavian vein were accomplished by 17 different physicians at four institutions utilizing a specially constructed peel-away introducer. Fourteen attempts (8.3 percent) to cannulate the subclavian vein were unsuccessful. There were four cases of pneumothorax (2.4 percent) and two cases of hematoma formation (1.2 percent). The procedure has the advantage of a rapid and atraumatic insertion of a variety of transvenous pacemaker electrodes, and the avoidance of surgical dissection for a venous entrance site.

Cardiac Catheterization↗
PubMed1979

Beat-to-beat stability of implanted pacemakers.

A method of measuring and analyzing beat-to-beat interval stability of implanted pacemakers has been devised, and a number of normal and failing pacers have been studied in this way. It was seen that normal pacer rates were remarkably stable, but that abnormalities in beat-to-beat interval were found in 67.4% of all failing pacers. The abnormalities consisted primarily of excessive interval (rate) scatter, linear and cyclic fluctuation, and transients following application of a magnet. It is expected that in problem cases a beat-to-beat analysis will be of help in differentiating normal from abnormal pacer function, and will provide confirmation signs of pacer failure; it may also uncover unusual and heretofore unpredictable failure modes.

Computers↗
PubMed1979

Early malfunction of transvenous pacemaker electrodes. A three-center study.

A 3-year study by three medical centers has revealed a 1-year electrode malfunction rate of 7.4%; most malfunctions occurred within the first 30 days. The incidence of unavoidable early malfunction (3.2%) fell within the 5% standards suggested by the committee report of the Inter-Society Committee on Heart Diseases. Incidences of obscure cause (3.2%) may be difficult to identify prospectively and may be, to a certain extent, unavoidable. The majority of the malfunctions (4.2%) showed specific clues that indicated that they were preventable. Successful repositioning was achieved on the first attempt in 80.6% of the cases with malfunction, and only 0.7% required ultimate myocardial electrode implantation. The principal clues to potentially unsatisfactory positioning included the presence of a large right ventricle with or without tricuspid insufficiency, current thresholds greater than 0.5 mA and ST-segment deviations on the intracardiac electrogram of less than 2 mV. Electrode malfunction may be more common with bipolar than with unipolar electrodes; but significant differences in the incidence of malfunction among different unipolar electrodes were observed. These data indicate that further developments in transvenous electrode design are warranted.

Arrhythmia, Sinus↗
PubMed1978

Characteristics of intracardiac electrograms.

Cardiac electrograms were measured on endocardial leads on patients undergoing pacemaker implantation. The data show that small area electrodes reduce R wave amplitude, decrease width of the complex, and increase slopes. The bandwidth of the electrogram increases as the electrode area decreases. The loading of the sensing amplifier changes these characteristics. Distortion is most pronounced for small area electrodes and low lead resistances.

Arrhythmias, Cardiac↗
PubMed1978

Symptomatic unilateral cannon "a" waves in a patient with a ventricular pacemaker.

A 64-year-old woman was referred because of intermittent pulsations of the left side of the neck, face, and scalp that were first noticed after the insertion of a ventricular pacemaker. The pacemaker had been inserted because of symptomatic 2:1 atrioventricular block. Right cardiac catherization showed cannon "a" waves, and phlebographic studies revealed stenosis of the right innominate and internal jugular veins. The symptoms were abolished by conversion to an atrial synchronous pacing system. Comments are offered on the hemodynamic findings, the "pacemaking syndrome", and the use of atrial synchronous pacing.

Brachiocephalic Veins↗