Programmable Pulse Generator Research Articles

A programmable multi-channel CMOS pulser chip to drive ultrasonic array transducers

This paper describes the development of a 16-channel programmable pulse generator Application Specific Integrated Circuit (ASIC). The General Purpose Pulser Chip (GPPC-16) can supply pulses delayed by up to 0.5 ms with a 1 ns time resolution. By employing novel design techniques, this has been achieved in standard CMOS technology. The design employs a CMOS delay line in conjunction with a phase-locked-loop. In this way a 16-phase clock is generated, which can drive 16 programmable counters. Currently the chip is being used to drive ultrasonic transducer arrays. The construction of these piezoelectric polymer arrays is also briefly discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Computerised performance testing of data acquisition facilities

The author describes a low-cost approach to performing automatic performance measurements on data acquisition modules and systems employed in physics research. A versatile programmable CAMAC pulse generator is described which produces accurately timed repetitive logic pulses whose width and repetition rate are set by software. The variable rate is useful in determining the performance of data acquisition systems over a wide range of data rates, while the variable width may be used in the automatic measurement of the characteristics of modules such as time-to-digital converters (TDCS). Using a time-to-amplitude converter (TAC), this width can be converted into a variable amplitude for testing analogue-to-digital converter (ADC) modules. Hardware and software aspects are described. Typical applications are discussed including automated performance measurements on a VAX 11/785 data acquisition system on a TAC/ADC combination.

A programmable Gaussian random pulse generator for automated performance measurements

This paper describes a versatile random signal generator which produces logic pulses with a Gaussian distribution for the pulse spacing. The average rate at the pulse generator output can be software-programmed, which makes it useful in performing automated measurements of dead time and CPU time performance of data acquisition systems and modules over a wide range of data rates. Hardware and software components are described and data on the input-output characteristics and the statistical properties of the pulse generator are given. Typical applications are discussed together with advantages over using radioactive test sources. Results obtained from an automated performance run on a VAX 11/785 data acquisition system are presented.

Cardiac pacing practices in the United States in 1985

Physicians active in pacemaker implantation and follow-up were surveyed to obtain a profile of permanent cardiac pacing practices in the United States during 1985. Questionnaires were sent to 628 physicians, mainly in New Jersey; 145 responses were received and analyzed. A separate questionnaire was sent to 9 pacemaker manufacturers to solicit information concerning the volume of pacemaker sales and their opinions on a variety of subjects. The rate of permanent pacemaker implantation declined for the first time: it dropped from 518 devices per million population in 1981 to 374 in 1985. Sinus node dysfunction was the chief indication for permanent pacing in 52% of primary implantations; conduction disorders of the atrioventricular node and His-Purkinje system accounted for 41% and ventricular tachyarrhythmias for 2%. Dual-chamber pacing modes were used less frequently than was predicted in 1981, accounting for 30% of primary and 19% of replacement pacemakers. More than 43% of programmable pulse generators were never reprogrammed after implantation. Surveys such as this continue to provide useful information despite obstacles encountered in the use of questionnaires. Important differences in practice patterns and outcomes were identified between surgeons and nonsurgeons, and between frequent and infrequent implanters. These differences reinforce the suggestion that implanters should work at a volume sufficient to maintain their expertise, and that cooperation between surgeons and nonsurgeons would lead to improvements in patient selection, surgical results and optimal pacemaker programming and follow-up care. Better results could be achieved by adopting the continent-wide system of a pacemaker registry now used in Eastern Europe and Great Britain.

A pulsed field gradient spin echo NMR spectrometer for diffusion coefficient measurements

A pulsed field gradient spin echo NMR spectrometer has been assembled by interfacing a programmable pulse generator and a data acquisition system designed and fabricated in our laboratory with other imported units. Calibration results of the magnetic field gradients are presented.

Routine reduction of pulse generator voltage.

The porous-tip electrode has led to a significant advancement in pacing system technology. Experience with 38 patients with unipolar tined CPI porous endocardial electrodes, is reported. All patients had programmable pulse generators, CPI model number 531. The voltage in this pulse generator can be reduced from 5 to 2.5 volts. The pulse width threshold (PWT) at implantation was 0.06 ms at 5 volts in all 38 patients, and the PWT at implantation varied between 0.06 and 0.16 ms at 2.5 volts, with a mean PWT of 0.092 +/- 0.026 ms. The 38 patients were restudied six months later. The mean PWT measured at 5 volts was 0.076 +/- 0.018 ms. The PWT measured at 2.5 volts varied between 0.08 and 0.30 ms with a mean PWT of 0.178 +/- 0.067 ms. Twenty-three patients were restudied one year after lead implantation. The PWT measured at 2.5 volts varied between 0.08 and 0.30 ms with a mean PWT of 0.156 +/- 0.061 ms. All of the pulse generators were reprogrammed to 2.5 volts. This permitted a substantial prolongation of the pulse generator life (three to five years) with an improvement in the cost effectiveness of the pulse generator.

Microprocessor-Based GPIB Compatible Programmable Pulse Generator

This paper presents a “Microprocessor-based, GPIB Compatible programmable pulse generator” which can be programmed both in the local mode and the remote mode. The programming parameters are (i) frequency, (ii) width or duration and (iii) amplitude, A new technique called direct digital synthesis with microprocessor control has been used for the generation of square waves from 1Hz to 1MHz in steps of 1Hz. The pulse generator realized using the above technique has arbitrarily high resolution, high switching speed, very low power consumption, high reliability and low cost. Also, GPIB interface circuits have been incorporated for remote operation.

Microcomputer-controlled pulse generator for an electron spin-echo spectrometer

A simple and low-cost microcomputer-controlled pulse generator for an electron spinecho (ESE) spectrometer has been constructed. The generator is composed of a programmable clock pulse generator, a programmable delay generator, and a pulse sequencer. The clock pulse generator supplies trigger pulses to the delay generator with the period ranging from 1 μs to 99,990 s. The delay generator is composed of two commercial time delay modules (Evans Associates Model 4145-2) and an additional 2.5 ns increment delay generator, and supplies reference and delayed pulses to the pulse sequencer. The pulse sequencer generates a series of pulses for the formation of microwave pulses and the detection of ESE signals. Most of the control data for the pulse generator are supplied from a microcomputer (NEC PC-9801). The software for the microcomputer is designed to measure two- and three-pulse echo envelopes and longitudinal relaxation times with the minimum time resolution of 2.5 ns.

Transition metal NMR spectroscopy - a probe into organometallic structure and catalysis

Abstract

Permanent cardiac pacing after the Fontan procedure

Permanent cardiac pacing after a Fontan procedure is complicated by complex cardiovascular anatomy. Of 332 patients undergoing the Fontan procedure at the Mayo Clinic, we evaluated 15 who postoperatively required permanent pacing (mean age 16.5 years, range 4 to 31 years). Underlying congenital cardiac defects included univentricular heart in nine patients, double-outlet right ventricle in three, and tricuspid atresia in three. The indication for pacing was postoperative heart block in seven patients, congenital heart block in five, postoperative sick sinus syndrome in two, and heart block because of previous operation in one. Pacemakers were implanted immediately postoperatively in 11 patients and 12 to 57 months later in four patients. VVI systems were used in nine patients, DDD in four, AAI in one, and a Medtronic Activitrax VVI in one. All ventricular leads were epicardial. Four atrial leads were transvenous endocardial and one was epicardial. Three patients died 4, 9, and 69 months later of causes unrelated to pacing. Among the 12 survivors, mean follow-up was 34 months (range 1 to 107 months). Two patients had a total of three episodes of loss of ventricular capture because of increased chronic thresholds. Our current approach to pacing after a Fontan procedure includes (1) intraoperative placement of temporary atrial and ventricular electrodes, (2) intraoperative attachment of a permanent ventricular epicardial lead for congenital or surgically induced high-grade atrioventricular block, (3) postoperative insertion of transvenous atrial leads if dual-chamber pacing is indicated, and (4) use of programmable pulse generators with high output capability.

Esophageal ECG recording--a valuable diagnostic tool in dual chamber pacing.

The interpretation of the ECG of a dual chamber pacemaker necessitates the identification of atrial activity. This is a prerequisite for the evaluation of pacemaker function and for the correct adjustment of programmable pulse generators. The assessment of atrial capture in standard 12-lead ECGs is, however, sometimes rather difficult. Esophageal ECG recording by means of a reusable unipolar electrode, inserted transnasally, and connected to a standard ECG recorder, is a simple, rapid and inexpensive method for the reliable identification of P-waves. Clinical examples are presented to illustrate the value of this technique in determining atrial capture and as a tool for the differential diagnosis of pacemaker-involved tachycardias. The use of esophageal ECG recording in the clinical follow-up of patients with dual chamber pacemakers is recommended.

Importance and Long-Term Utility of a Multiparameter Programmable Pulse Generator

Almost all pacemakers currently implanted in patients in the United States are now capable of some degree of noninvasive programmability. Although programmability seems to be a very useful feature and allows flexibility in the patient's pacemaker system, the use of programmability in the late follow-up period has not been well substantiated. We compare the use of programmability in the early and late postoperative periods in 100 consecutive patients who received a multiparameter programmable pulse generator. Programmability is definitely a desirable feature, particularly for alterations in rate, pulse width, and sensitivity.

Multiprogrammable cardiac pacemakers: Applications, results, and follow-up

More than 50 percent of patients with implanted pulse generators live more than 5 years and 35 percent survive beyond 10 years. For such patients, programmable pulse generators offer the flexibility to safely prolong battery life and to alter pacing function based on clinical and electrophysiologic requirements. Further, the potential to diagnose and treat pacing system malfunctions noninvasively in the future may significantly reduce the discomfort, inconvenience, and cost of reoperation. Physicians should select programmable models based on proved system reliability, clinical needs, and the availability of supervised follow-up programs. Finally, the safe and efficacious application of programmable pulse generators requires knowledge of pacing electrophysiology and techniques, and a thorough acquaintance with the operating characteristics of the systems selected for implantation.

Successful management of pacing system malfunctions without surgery: the role of programmable pulse generators.

The value of programmable pulse generators for correcting pacing system malfunction without surgical revision was assessed in 293 patients. Twenty-five patients (8.5%) developed malfunctions from one day to 38 months after implant. Of these, 16 or 64% were successfully managed by programming alone, while nine patients required lead repositioning or a new lead. The majority (75%) of isolated pacing and sensing malfunctions were corrected by programming, but programming restored normal pacing function in only one of five patients who had combined sensing and pacing malfunctions which appeared early after pacemaker insertion. We conclude that programmable pulse generators are particularly useful for managing isolated pacing or sensing malfunctions. However, programmability is not a substitute for careful lead placement.

A programmable pulse generator with high output option.

A new pulse generator, with a programmable high output option, was implanted in fifteen patients and studied for eight to ten months postoperatively. This feature is designed to combat exit block. It was useful in one patient who developed a form of exit block following a silent myocardial infarction. Muscle stimulation was rare, even though the system is unipolar. The high output option seems to be a desirable feature and should probably be available in all multiprogrammable pulse generators.

Programmable digital pulse generator for proton enhanced 13C high resolution NMR in solids

A programmable pulse generator is described for NMR spectrometers. The pulse generator can operate either in a single cycle mode where up to 16 pulses can be given sequentially or, in the double cycle mode, a programmable number (</=15) of these pulses can be repeated n times (n</=99) before the rest of the 16 pulses are completed. The length of all these pulses can be programmed, manually or by computer. As an example the programming of the pulse generator for a multiple contact proton enhanced (13)C NMR experiment is given.

A programmable coherent pulse generator

A programmable pulse generator using commercially available solid state circuit modules is described. Analogue timers, which give pulse and interval times from 500 ns to 80 s, are used while the final pulse sequence remains coherent with the input RF reference signal. Various pulse sequences can be selected rapidly using simple preprogrammed plug-in diode-only memory cards. Complex pulse trains can be generated easily using the program loop capability. Various programmable gating signals are available.