Search PubMed⌕ Search

Biomedical subjects

A W Nathan

Publications and source records attributed to A W Nathan.

80 records · Page 5Linked to original sources
PubMedDate not supplied

Noninvasive recording of the His bundle electrogram in neonates.

Twenty-seven normal, nonsedated neonates had high-resolution electrocardiography performed during the first four days of life. Using high amplification, analogue and digital filters, and signal averaging, easily defined His bundle deflections of 0.75-7.75 (mean 2.5) microV were detected in 25 (92.6%) of the 27 babies. The PH interval was 60-105 (mean 83) ms and the HV interval 10-25 (mean 17) ms. Surface His bundle electrocardiography is easily performed in the neonate and, as might be predicted, conduction intervals are considerably shorter than those seen in older age groups.

Bundle of His↗
PubMedDate not supplied

Software control of sensing and stimulation for cardiac electrophysiological study.

A software-controlled cardiac stimulator for clinical investigations is described. The stimulator is programmed by the user at a keyboard, while current status and values of parameters are presented on a visual display screen. A menu of predefined cardiac electrophysiological tests is available for user selection. Validity checks on data keyed in by the user and internal checks on safe pacing limits are incorporated in case of malfunction or user error. The system consists of a separate relatively simple isolated sensing and stimulation unit which communicates, via a standard digital input output interface, with a controlling microcomputer. All timing and control functions are performed in software by the computer. The use of high-level FORTRAN as the main programming language provides the system with a high degree of adaptability.

Computers↗
PubMedDate not supplied

Myocardial revascularisation in elderly patients with refractory or unstable angina and advanced coronary disease.

BACKGROUND: Elderly patients with ischaemic heart disease are often treated more conservatively and for longer than younger patients, but this strategy may result in subsequent invasive intervention of more advanced and higher risk coronary disease. METHODS: We performed a retrospective analysis of 109 patients aged > or = 70 years (mean age 74 years, 66% men), who presented with angina refractory to maximal medical treatment or unstable angina over a 2-year period (1988-1990), to compare the relative risks and benefits of myocardial revascularisation [coronary artery bypass grafting (CABG) and percutaneous transluminal coronary angioplasty (PTCA)] in this higher-risk age group. RESULTS: Sixty patients underwent CABG and 49 patients PTCA. There were eight periprocedural deaths in total (six in the CABG group, and two in the PTCA group, P = 0.29). Six patients in the CABG group suffered a cerebrovascular accident (two fatal). Acute Q-wave myocardial infarction occurred in one patient in the CABG group and in two patients in the PTCA group. The length of hospital stay was longer for the CABG group (CABG group 11.4 +/- 5.4 days, range 7-30 days, PTCA group 7.4 +/- 7.6 days, range 1-39 days, P = 0.01). Outcome was assessed using the major cardiac event rate (MACE; i.e. the rate of death, myocardial infarction, repeat CABG or PTCA). The cumulative event-free survival in the CABG group in 1, 2 and 3 years was 87, 85 and 85%, respectively. In contrast, in the PTCA group it was 55, 48 and 48% (P = 0.0001). Age, sex, number of diseased vessels, degree of revascularisation and left ventricular function were not predictive of the recurrence of angina in both groups. Actuarial survival (total mortality, including perioperative mortality) was lower at 1 year in the CABG group due to the higher perioperative mortality, but similar in both groups after the second year (P = 0.62). CONCLUSIONS: Elderly patients with refractory or unstable angina who are revascularised surgically have a better long-term outcome (less frequent event rate of the composite end-point--myocardial infarction, revascularisation procedures and death) compared with those who are revascularised with PTCA. This benefit is been realised after the second year. Total mortality is similar in both groups after the second year. Therefore elderly patients who are fit for surgery should not be denied the benefits of CABG. PTCA may be regarded as a complementary and satisfactory treatment, especially for those whose life expectancy is limited to less than 2 years. The use of stents may improve outcome in the PTCA group and this needs to be evaluated.

Aged↗
PubMedDate not supplied

A solid state recorder for ambulatory monitoring of pulmonary-artery pressure.

A compact, portable recording system has been developed to record pulmonary-artery pressure in ambulatory patients. A transducer mounted on the tip of a conventional cardiac catheter is inserted percutaneously and positioned in the main pulmonary artery. Analogue circuitry, including peak and trough detectors, pre-processes the pressure/voltage waveform to yield sampled values for the systolic and diastolic pressures. Systolic and diastolic values sampled every 30 s are digitized and stored in CMOS semiconductor memory. Data acquired over a prolonged period is transferred to a microcomputer for permanent storage and subsequent analysis. Five patients were each successfully monitored for at least 24 h. The zero-level drift was less than 1% and gain stability was also better than 1% over 48 h. This device allows practical, safe, reliable and prolonged pressure recording and has wide-ranging clinical potential.

Ambulatory Care↗