Flow patterns in the aortic root and the aorta studied with time-resolved, 3-dimensional, phase-contrast magnetic resonance imaging: implications for aortic valve-sparing surgery

OBJECTIVE: Sparing the aortic valve has become a surgical option for patients who require repair of aortic root ectasia and have normal valve leaflets. Surgical approaches to valve sparing differ with regard to preservation of the native sinuses of Valsalva. The role of the sinuses and the importance of maintaining them remain controversial. METHODS: By using a time-resolved, 3-dimensional, phase-contrast magnetic resonance imaging technique, aortic root and aortic blood velocity data were acquired from 2 patients with Marfan syndrome 6 months after aortic valve-sparing surgery with straight Dacron grafts and contrasted with data from 6 normal volunteers. RESULTS: In normal aortas vortical blood flow became apparent in the individual sinuses after peak systole. The vortices filled the available space behind the valve leaflets and persisted until diastole, expanding and moving inward during aortic valve closure. In contrast, no vortices were observed in the postoperative patients with Marfan syndrome with negligible sinuses. CONCLUSIONS: Changes in supravalvular flow accompany loss of sinus architecture. Whether the presence, size, and velocity of supravalvular vortices affects the function or durability of the preserved aortic valve remains to be studied.     

Hypertension: pathophysiology and treatment

Arterial hypertension is a major cause of morbidity and mortalitybecause of its association with coronary heart disease, cerebrovasculardisease and renal disease. The extent of target organ involvement(i.e. heart, brain and kidneys) determines outcome. North Americanstudies have shown that hypertension is a major contributorto 500 000 strokes (250 000 deaths) and 1 000 000 myocardialinfarctions (500 000 deaths) per annum.     

The surgical hypertensive patient

We reviewed the pathophysiology and treatment of hypertensionin a recent edition of this journal (see key references). Inthis article, we discuss the management of the hypertensivepatient presenting for surgery and anaesthesia.     

A framework for assessing risks to children from exposure to environmental agents

In recent years there has been an increasing focus in environmental risk assessment on children as a potentially susceptible population. There also has been growing recognition of the need for a systematic approach for organizing, evaluating, and incorporating the available data on children's susceptibilities in risk assessments. In this article we present a conceptual framework for assessing risks to children from environmental exposures. The proposed framework builds on the problem formulation-->analysis-->risk characterization paradigm, identifying at each phase the questions and issues of particular importance for characterizing risks to the developing organism (from conception through organ maturation). The framework is presented and discussed from the complementary perspectives of toxicokinetics and toxicodynamics.     

Proxy and surrogate consent in geriatric neuropsychiatric research: update and recommendations

OBJECTIVE: The ethics of involving decisionally incapable adults in research will continue to grow in importance as more research is conducted to address the problems of decisionally impaired persons, especially elderly persons. The authors provide an updated discussion, critique, and recommendations regarding the need for clear legal and regulatory policy on this issue. METHOD: The authors summarize and build on discussions of a workshop on proxy and surrogate consent in geriatric neuropsychiatric research sponsored by the Aging Research Consortium of the National Institute of Mental Health. They incorporate the views of various stakeholders present at the workshop as well as review recent federal and state initiatives, recent empirical research and media reports, and various commission reports and relevant regulations. RESULTS: Despite a wave of initiatives in the late 1990s to clarify policy, surrogate consent for research continues to be a murky legal area and incapable subjects in the United States still lack clear regulatory protection. There is evidence that conservative risk management strategies by institutional review boards and their institutions may severely restrict research with decisionally impaired subjects. A passive approach to this problem may no longer be feasible. A recent federal advisory report on human research protections and legislative initiatives in some states could begin to provide a blueprint for future policy making. Interim recommendations for various stakeholders are given. CONCLUSIONS: It is imperative that the scientific community, patients and their advocates, and policy makers at all levels establish a constructive dialogue to clarify ethical and legal standards in the area of proxy and surrogate consent for research.     

Renal artery disease: diagnosis and management

Renal artery stenosis (RAS) is most commonly due to either fibromuscular dysplasia or atherosclerosis. The former predominates in young women while atherosclerosis is usually encountered in individuals over the age of 55. The most common clinical manifestation of fibromuscular dysplasia is hypertension, which can frequently be cured or significantly improved with percutaneous balloon dilation. Atherosclerotic RAS may present with hypertension, renal failure (ischemic nephropathy), recurrent episodes of congestive heart failure and flash pulmonary edema or may be discovered incidentally during an imaging procedure for some other reason. Screening tests for RAS have improved considerably over the last decade. While captopril renography was utilized almost exclusively in the past, duplex ultrasound of the renal arteries or magnetic resonance angiography have replaced other modalities as the screening test of choice in many centers. Rarely does an arteriogram have to be performed for diagnostic purposes only. Management of RAS consists of three possible strategies: medical management, surgical management or percutaneous therapy with balloon angioplasty and stent implantation. The treatment of choice to control hypertension in patients with fibromuscular disease is percutaneous angioplasty. Renal artery stenting has replaced surgical revascularization for most patients with atherosclerotic disease who meet the criteria for intervention.     

Energy-dense meals improve energy intake in elderly residents in a nursing home

BACKGROUND: Several studies have shown that malnutrition is common among nursing home residents. AIM: We hypothesized that addition of natural energy-dense ingredients to a standard diet would improve voluntary energy intake and ability to perform activities of daily living (ADL) and decrease infections in elderly residents under nursing home care. METHODS: Thirty-five residents in a municipality nursing home (median age 83 years) were served either a standard diet (1600 kcal/day) (control group, n=18) or the same meals fortified with natural energy-dense ingredients (2100 kcal/day) (experimental group, n=17). Energy intake and ADL function were measured before and after the intervention. All episodes of infection were registered. Non-parametric statistics were used. RESULTS: Energy intake increased in the experimental group from 23.5 (21.3-28.5) kcal/kg/body weight before, to 31.9 (29.7-33.7) kcal/kg/body weight during the intervention (P<0.001). There was no change in energy intake in the control group. ADL function in the experimental group was unchanged, while it decreased significantly in the control group (P<0.001). The number of infections tended to be lower in the experimental group than in the control group (5 vs 13). The cost for the energy-dense ingredients was approx. 0.11 EUR per resident and day. CONCLUSIONS:Addition of natural energy-dense ingredients to regular meals is an inexpensive way to improve voluntary energy intake in elderly nursing home residents, a treatment that was accompanied by maintained ADL function.     

Aseptic meningitis epidemic during a West Nile virus avian epizootic

While enteroviruses have been the most commonly identified cause of aseptic meningitis in the United States, the role of the emerging, neurotropic West Nile virus (WNV) is not clear. In summer 2001, an aseptic meningitis epidemic occurring in an area of a WNV epizootic in Baltimore, Maryland, was investigated to determine the relative contributions of WNV and enteroviruses. A total of 113 aseptic meningitis cases with onsets from June 1 to September 30, 2001, were identified at six hospitals. WNV immunoglobulin M tests were negative for 69 patients with available specimens; however, 43 (61%) of 70 patients tested enterovirus-positive by viral culture or polymerase chain reaction. Most (76%) of the serotyped enteroviruses were echoviruses 13 and 18. Enteroviruses, including previously rarely detected echoviruses, likely caused most aseptic meningitis cases in this epidemic. No WNV meningitis cases were identified. Even in areas of WNV epizootics, enteroviruses continue to be important causative agents of aseptic meningitis.     

Regional Angiogenesis with Vascular Endothelial Growth Factor (VEGF) in peripheral arterial disease: Design of the RAVE trial

Background

Patients with intermittent claudication caused by infrainguinal atherosclerosis have limited pharmacologic options “Therapeutic angiogenesis” is a novel treatment approach that seeks to improve perfusion of ischemic limbs by the induction of collateral vessel formation. This trial is a phase 2 randomized double-blind placebo-controlled proof of concept trial that will use an intramuscular adenoviral gene transfer approach of vascular endothelial growth factor, 121 isoform (Ad_GVVEGF_121.10) to patients with severe IC caused by infrainguinal disease.

Methods

This is a phase 2, double-blind, randomized, placebo-controlled, dose-finding, multicenter study. Patients with severe intermittent claudication caused by infrainguinal atherosclerosis predominantly involving the superficial femoral artery confirmed with imaging studies that meet inclusion criteria will be stratified on the basis of the presence or absence of diabetes mellitus and randomized in a 1:1:1 fashion to low dose (4 × 10⁹ particle units), high dose (4 × 10¹⁰ particle units), or placebo arms (35-36 patients per group). Subjects are required to have exercise-limiting IC in the index extremity during 2 qualifying exercise treadmill tests, with peak walking times between 1 and 10 minutes. A single dose of Ad_GVVEGF_121.10 will be administered as 20 intramuscular injections throughout the area of the lower limb requiring collateralization.

Results

The primary efficacy parameter for the Regional Angiogenesis With Vascular Endothelial Growth Factor (RAVE) trial is the change in peak walking time at 12 weeks compared with baseline. The sample size is expected to provide an 80% power to detect a difference of 1.5 minutes between any of the 2 treatment groups and the placebo group. Secondary efficacy parameters include claudication onset time, hemodynamic effects of therapy assessed with ankle-brachial index, assessment of physical impairment, and health-related quality of life as measured with the Walking Impairment Questionnaire and SF-36 Health Survey. All randomized patients will also be evaluated for safety.     

Aortic valve replacement with pericardial valves in patients with small aortic roots. Clinical results in a consecutive series of patients receiving 19 and 21 mm prostheses

OBJECTIVE: To determine how second generation pericardial valves perform in patients with small aortic roots. DESIGN: Ninety patients who underwent isolated aortic valve replacement (AVR) with 19 or 21 mm Mitroflow or Carpentier-Edwards (Perimount) valves between 1989 and 1996 were studied. Mean age was 78 years. Concomitant coronary bypass surgery was performed in 41%. RESULTS: Thirty-day mortality was 5.6%. Ninety-seven percent had acceptable transprosthetic mean pressure gradients (25 mmHg or less) 1 week after surgery. Follow-up was 100% complete and 76% of the patients were alive after a mean of 5 years. There was no structural valve failure or valve thrombosis. One patient required reoperation for perivalvular leak. Four patients had transient ischemic attacks and seven had strokes. These figures are, however, within the expected range for the age. CONCLUSION: Second generation pericardial valves perform well in elderly patients with small aortic roots. Postoperative hemodynamics are acceptable, valve durability of up to 8 years adequate, and the clinical results good, considering the age of the patients.