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Biomedical subjects

V Parsonnet

Publications and source records attributed to V Parsonnet.

At least 145 records · Page 8Linked to original sources
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↗
PubMed1977

Permanent pacing of the heart: 1952 to 1976.

The theory and science of electrical pacing of the heart is scarcely 2 decades old, but developments in these areas have in a way revolutionized modern cardiology. This report, basically a review of the major developments during that time, describes the present state of the art, and calls attention to the many people who have brought us to this point. Results of a recent national survey reveal that about 156,000 patients in the United States are living with implanted pacemakers or about 1 in every 1,300 persons. The rate of new implants is 270/million each year, the highest in the world. The impact of such a volume is considerable, affecting industrial growth, federal legislation and control, insurance plans and a multitude of medical programs. New power sources, some touted to last a lifetime, will have a great impact but will not change the current state of the art materially because 30 percent or more of pacemaker operations are for problems other than routine battery exhaustion. The need for improvements in other pacemaker components is emphasized.

Arrhythmias, Cardiac↗