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Biomedical subjects

M L Marks

Publications and source records attributed to M L Marks.

11 recordsLinked to original sources
PubMed1995

Long QT syndrome associated with syndactyly identified in females.

The identification of female children with this syndrome is evidence that this disorder is not X-linked in inheritance. Possible inheritance modes still include autosomal recessive or, more likely, a de novo mutation, given the absence of family history in any of the patients. Children of both sexes with syndactyly should be screened with an electrocardiogram for this syndrome. Female children with this syndrome may have an increased risk of sudden death similar to male children.

Electrocardiography↗
PubMed1995

A new form of long QT syndrome associated with syndactyly.

OBJECTIVES: The purpose of this study was to characterize a possible association between long QT syndrome and syndactyly. BACKGROUND: Long QT syndrome causes syncope and sudden death from ventricular arrhythmias. Syndactyly is a developmental disorder that causes webbing of the hands and feet. Both disorders can be inherited as isolated, autosomal dominant traits, but an association between them has not been established. METHODS: We identified three children with long QT syndrome, atrioventricular (AV) block and simple syndactyly. Phenotypic and laboratory data were obtained from families, attending physicians and medical records. RESULTS: All patients had bilateral cutaneous syndactyly and were diagnosed with long QT syndrome within the 1st 2 years of life. Structural heart disease, particularly a patent ductus arteriosus, was present in all three patients. Analysis of electrocardiograms showed marked prolongation of the QT intervals with rate-corrected QT intervals of 633, 628 and 680 ms, respectively. Transient AV block was also noted. Two of the three children died suddenly despite treatment with beta-adrenergic blocking agents and permanent pacing. CONCLUSIONS: We postulate that these children have a new form of long QT syndrome associated with syndactyly and a high risk of sudden death. The association of syndactyly with long QT syndrome may provide insight into the mechanisms underlying both disorders. Patients with syndactyly should be evaluated for the presence of long QT syndrome, and if it is found, aggressive treatment may be warranted.

Child, Preschool↗
PubMed1994

Biphasic waveform defibrillation using a three-electrode transvenous lead system in humans.

INTRODUCTION: Biphasic waveform defibrillation is not always more efficacious than monophasic waveform defibrillation. METHODS AND RESULTS: Waveform efficacy appears to vary with the lead system used. In this prospective, randomized study, defibrillation efficacy with biphasic and monophasic single capacitor 120-microF, 65% tilt pulses was compared for a lead system consisting of right ventricular (RV), chest patch (CP), and superior vena cava (SVC) electrodes. Although this lead system is commonly used with monophasic pulses in transvenous defibrillators, few studies have examined the defibrillation efficacy of this lead system in man for biphasic waveform defibrillation. Fourteen cardiac arrest survivors undergoing defibrillator implantation were included in the study using pulses delivered from a cathodal RV electrode simultaneously to anodal SVC and CP electrodes. Biphasic and monophasic waveforms were recorded oscilloscopically to acquire defibrillation threshold (DFT) data on leading edge voltage requirements and for stored energy. The monophasic DFT voltage was 661 +/- 177 V compared to the biphasic DFT voltage of 451 +/- 185 V (P < 0.0001). The monophasic DFT stored energy was 28.0 +/- 13.4 J compared to the biphasic DFT stored energy of 14.1 +/- 12.4 J (P < 0.0001). The stored energy DFT was < or = 15 J in only 2 of 14 patients (15%) with monophasic defibrillation but < or = 15 J in 10 of 14 (71%) patients with biphasic defibrillation. CONCLUSION: These findings indicate that biphasic defibrillation with an RV, SVC, CP transvenous electrode system is substantially more efficient than monophasic defibrillation, allowing for higher numbers of patients to receive transvenous defibrillators with a relatively simple lead system at a satisfactory cutoff DFT safety margin of 15 J.

Adolescent↗
PubMed1992

A study of the cardiac effects of bromochlorodifluoromethane (halon 1211) exposure during exercise.

Bromochlorodifluoromethane (halon 1211, a fire extinguisher), like other fluorocarbons, has been linked with ventricular arrhythmias and myocardial depression. Ten healthy firefighters, aged 40-50, were exposed to 1,000 ppm halon while exercising, in a double-blind, placebo-controlled crossover experiment, and were monitored during and after exposure. Complex ectopy (ventricular couplets and idioventricular rhythm) occurred in two subjects with halon, but none with placebo. One subject had 49.5 ventricular premature beats (VPB)/hour during the period of halon exposure and subsequent 8 hours and only 8.7 VPB/hour during the same period of placebo. In addition, 8 of the 10 subjects had a smaller systolic blood pressure rise during exercise with halon than with placebo. None of the observed differences was statistically significant. These results are consistent with findings in other investigations, suggesting that occupational fluorocarbon exposures may be cardiotoxic in certain individuals, although the small sample sizes used in this and other studies have resulted in limited statistical power to demonstrate this effect.

Adult↗
PubMedDate not supplied

Surviving and succeeding during mergers and consolidations.

Mergers and acquisitions are occurring at a feverish pace throughout U.S. business. Even firms that are not seeking to grow through acquisition are making defensive moves--internal reorganizations that involve cutting out entire layers of management or divesting whole divisions--to raise stock prices in hopes of fending off unwanted takeover bids. Mergers and reorganizations are especially prominent in the health care industry. The push for cost containment enhances the attractiveness of perceived synergies to be gained through combination. Moreover, the specter of an industry shake out prompts executives to adopt an "eat or be eaten" mentality.

Health Facilities↗
PubMedDate not supplied

Managing during a merger.

In the November-December 1988 issue of Physician Executive, Dr. Marks' article outlined typical reactions to the uncertainty of being involved in a merger or consolidation. The article introduced the concept of the "merger syndrome," which encompasses executives' stressful reactions to a combination and the development of a crisis management orientation. The bottom line, if the syndrome is allowed to go unchecked, can be marred executive and employee performance and poor financial and operational results. The merger syndrome is a prime reason that two-thirds of all mergers and acquisitions are financial failures. Consumed by their reactions to mergers, executives frequently lose touch with the needs of employees. In this article, the author summarizes steps that can be taken by executives to help their employees cope with the trauma of merger; to minimize negative employee reactions, such as reduced productivity and increased turnover; and to build effective postmerger teams.

Communication↗