James C. Broadbent

Pacemaker contact sensitivity

In a patient who had 4 cardiac pacemakers implanted and removed, pruritus, redness, and swelling of the skin overlying the pacemaker developed at intervals of 6 weeks to 17 months after insertion. Patch testing showed a 2 + reaction to titanium. The positive result of this test, the titanium case of the generator, and the history of multiple local reactions around the generator site pointed toward contact sensitivity to the pacemaker. Although a review of the literature indicates that this problem is rare, it is of extreme importance to the patient with pacemaker contact dermatitis.

Quantitation of left ventricular myocardial fiber hypertrophy and interstitial tissue in human hearts with chronically increased volume and pressure overload.

Using new techniques, we quantitated left ventricular myocardial fiber hypertrophy and interstitial tissue in four groups of autopsied hearts free of coronary disease: 1) 22 normal hearts, 2) 20 hearts from patients with mitral incompetence (NYHA Class Il-IlI) who died early after mitral valve replacement from causes other than cardiac failure, 3) 22 hearts from patients with mitral incompetence (NYHA Class III-IV) who died early after mitral valve replacement from cardiac failure with low cardiac output syndrome, and 4) 22 hearts from patients with hypertensive heart disease (NYHA Class II-III). Myocardial fiber hypertrophy was quantitated by measuring cross-sectional myocardial fiber diameter; the proportion of interstitial tissue was quantitated by using a computerized, high-resolution video image-digitizing system. Myocardial fiber average diameter in groups 2, 3 and 4 was significantly higher than group 1. The proportion of interstitial tissue was significantly increased in group 3. In chronic mitral incompetence an increase in left ventricular interstitial tissue may play a role in the development of severe cardiac failure.

Indicator-Dilution Curves in Acyanotic Congenital Heart Disease

Dye dilution and cardiac catheterization technics were used to study 36 patients with a central left-to-right shunt due to patent ductus arteriosus, atrial septal defect or ventricular septal defect. The configuration of dilution curves following injection of dye into an antecubital vein was similar in all instances. Principal abnormalities of the curve were a prolongation of its disappearance slope and a relative reduction in the peak concentration of dye. Quantitatively expressed, these abnormalities could be correlated with the magnitude of the left-to-right shunt. Curves of normal contour were observed following surgical closure of the ductus arteriosus, and in patients with isolated pulmonary stenosis.

Aortic and Mitral Valve Replacement with Cloth-Covered Braunwald-Cutter Prosthesis: A Three-Year Follow-up

From February, 1971, through February, 1974, heart valves of 510 patients were replaced with cloth-covered Braunwald-Cutter prostheses. The data indicate that cloth encapsulation of the prosthetic cage is associated with a reduction in thromboembolic complications, particularly for mitral valves. Cloth wear on the distal strut, however, is not prevented by use of a Silastic poppet and appears to be a typical finding in aortic valves recovered or inspected after 3 months. Excessive poppet wear has also been noted in the aortic position; poppet embolization has occurred on 2 occasions, and a third patient was found, at the time of reoperation for periprosthetic leak, to have opppet wear sufficient to permit embolization. Although there have been no reports of clinical malfunction of the mitral prosthesis at the time of this writing, further long-term observation of these patients appears warranted.

Two Decades of Cardiac Pacing at the Mayo Clinic (1961 Through 1981)

Pacemaker procedures performed at the Mayo Clinic for the years 1961, 1971, and 1981 were reviewed to examine the changes that have occurred in a large pacemaker practice during the 2 decades since the advent of pacemaker therapy. Major changes in trends and practice have occurred; in addition to numerical growth, the indications for permanent pacing and the technologic alternatives available have expanded considerably. The increasing choices available today (in all areas of pacemaker practice) provide a challenging stimulus to physicians as they seek the best clinical options in patient care.

Initial and Early Follow-up Assessment of the Clinical Efficacy of a Multiparameter-Programmable Puise Generator

Recent advances in pacemaker technology have produced noninvasively multiparameter‐programmable puise generators that have the potential for resolving complications that result from the pacing system and forproviding a mechanism whereby adjustments can be made for the specific needs of a patient without corapromising reliability and longevity. These applications were assessed by analyzing the initial indications, clinical efficacy, and reliability in 100 consecufive patients who received a multiparameter‐program‐mable puJse generator. Data analysis showed that 78% of the 100 patients had changes in rate programmed, 16% in pufse width, and 5% in sensitivity. Program‐mability was utilized for voJtage amplitude (one patient) but was not utilized for hysteresis and refractory period. Although progrtimming changes (rate and pulse width) generally could have been accomplished with simpler units, program‐mability for sensitivity made it possible to solve pacemaker problems in five patients and clearly eliminated the need for reoperation in two patients. The compact size of the multiparameter‐programmable pulse generator has allowed its use in patients in the pediatric age group, patients with a small frame, and patients with a major concern about cosmetic appearance. Programming sensitivity for proper sensing of the atrial signal allows use of the multiparameter‐programmable pulse generator as an atrial pacemaker. This was done in one pediatric patient who also benefited from suppression of atrial overdrive. There have been no episodes of spurious programming. Reliabitity has not been sacrificed by the increased complexity of this unit. If preimplant criteria for use of a multiparameter‐program‐mable puise generator are too sfrict, this may limit its potential therapeutic value because the need for its flexible characleristics is unpredictable.

Severe Hyperkalemia in a Case of Chronic Renal Insufficiency

Severe hyperkalemia in the presence of chronic renal insufficiency may cause fatal cardiac arrest unless diagnosed early and treated promptly.Hyperkalemia may be diagnosed immediately through study of serial electrocardiographic tracings. The first electrocardiographic changes observed seem related to a disturbance in depolarization, excitation or conduction processes.Medical treatment of hyperkalemia includes reduction of potassium intake and protein catabolism, correction of renal acidosis, and maintenance of an adequate urinary output.