Nariman Malik, BSc

Introduction
Mitral regurgitation is a common valvular heart disease, especially in the elderly.¹ It is defined as a condition in which there is an abnormal flow of blood from the left ventricle to the left atrium across an incompetent mitral valve during ventricular systole.² The mitral valve consists of four main components: the annulus, anterior and posterior leaflets, the chordae tendinae and the papillary muscles. Mitral regurgitation has a number of underlying etiologies that can be broadly classed into two groups: mitral regurgitation due to organic disease (e.g. rheumatic disease or infective endocarditis) or mitral regurgitation due to functional causes (regurgitation results from myocardial dysfunction as opposed to valvular problems). In developed countries, the etiologic profile of mitral regurgitation has changed over recent years due to the decreased incidence of rheumatic heart disease.³ Mitral regurgitation is most frequently due to degenerative and ischemic causes in the western world.⁴ See table 1

D'Arcy L. Little MD, CCFP
York Community Services, Toronto

Relenza (zanamivir), an orally-inhaled anti-viral medication effective against all known strains of the influenza virus, was approved by the Therapeutic Products Program of Health Canada on November 3, 1999.

Epidemiology
It is estimated that in Canada influenza affects between 10 to 15% of the population (between 3 and 5 million people) each year. The number of affected persons can be as high as 80% of nursing home residents. In addition, these infections result in about 75,000 hospitalizations and 7,000 deaths yearly.¹ In economic terms, flu-related costs to the Canadian economy during the 1997-98 flu season were estimated to be over $1 billion.²

The Mainstay of Treatment for Influenza
The influenza vaccine has been and remains the mainstay of prophylactic protection against influenza, and is recommended for elderly and high-risk patients, their household contacts, and health-care personnel. Under ideal circumstances, in healthy, young adults, vaccine effectiveness is in the range of 70-90%, with much lower effectiveness in the elderly (30-50%).³ For optimal results, it is recommended as a single 0.5 ml IM dose to be given from October through mid-November, although it can be given from September to the end of the influenza season.

Jason Park, BSc

Chronic aortic regurgitation is common in the elderly. Indeed, a Finnish study looking at the prevalence of aortic valve abnormalities found that 13% of a random, asymptomatic elderly population had moderate to severe evidence of aortic regurgitation when imaged with echocardiography.¹ Although chronic aortic regurgitation is usually insidious in its course, it can progress to cause permanent myocardial damage and congestive heart failure. Major indications for surgical correction of severe chronic aortic regurgitation are the onset of more than mild symptoms, such as dyspnea, or echocardiographic evidence of left ventricular systolic dysfunction. Surgery should be performed before systolic dysfunction is significant in order to limit progression of the disease and possible irreversible myocardial dysfunction. Careful follow-up of patients with chronic aortic regurgitation is required, including a detailed history, physical examination, and echocardiography, in order to optimize the benefits of surgery and limit the possibility of permanent myocardial damage.

Etiology and Pathophysiology
Chronic aortic regurgitation results from incomplete closure of the aortic valve due to disease of either the aortic root or the aortic valve itself. A frequent cause of aortic regurgitation is idiopathic aortic root dilatation, which is associated with hypertension.

Sheldon Singh, BSc

Valvular heart disease is an increasingly common cause of congestive heart failure in the elderly population. Stenosis of the aortic valve is one type of valvular heart disease that can lead to congestive heart failure. Approximately 28,000 aortic valve replacements were performed in the United States in 1994. Sixty-one per cent of these were performed in individuals over age 65. This procedure is the second most common open-heart procedure performed in the elderly after coronary bypass grafting.

In adults, aortic stenosis may be due to previous rheumatic disease or calcification of a congenital bicuspid valve or normal tricuspid aortic valve. Although common worldwide, rheumatic disease is uncommon in North America and Europe. However, because of the increasing aging population, degenerative aortic valve calcification constitutes a substantial health problem.¹

Anatomy
A normal aortic valve is tricuspid. Each leaflet is flexible and composed of three layers covered with endothelium on each side. Degenerative calcific disease is characterized by discrete focal lesions on the aortic side of the leaflet. It is typically an active inflammatory process that bears some resemblance to atherosclerosis; there are protein and lipid infiltration as well as macrophages, foam cells, and the occasional T cell.² The risk factors for aortic valve disease include age, male gender, lipoprotein a, hypertension, smoking, cholesterol and diabetes.

Joyce So, BSc

While thrombolytic therapy has become an established part of treatment for acute ischemic heart disease, the controversy continues regarding its potential and practical use in acute ischemic stroke. In a situation where time is of the essence, is thrombolysis the best available solution?

Acute ischemic stroke (AIS), or "brain infarction", is most commonly a result of intracerebral artery occlusion due to embolism from proximal sites such as the internal carotid arteries, heart or aorta. Unlike cardiac arrest, where brain viability is measured in minutes, AIS presents with a mixture of salvageable tissue, allowing for a therapeutic window that can last several hours. While the definitive time frame has yet to be pinned down, the generally accepted mantra "Time is Brain" reflects the notion that prognosis is improved by early intervention. The question now is whether there is a role for thrombolytic therapy in the management of AIS.

The two most prominent candidates for use in thrombolytic AIS therapy are streptokinase and recombinant tissue plasminogen activator (rtPA), both serine proteases that catalyze the conversion of plasminogen to plasmin, which digests fibrin clots.

D'Arcy L. Little, MD, CCFP
York Community Services, Toronto, ON

Introduction
Every year there are approximately 50,000 strokes in Canada. Currently, close to 300,000 Canadians are stroke survivors. As stroke is an age-related condition, the number of strokes is predicted to increase as the Canadian population ages. The resultant national cost, which is estimated at 2.7 billion annually, will also increase unless improvements are made to prevention and treatment.¹ Approximately 1 in 6 survivors of a first stroke experiences a recurrent stroke over the next 5 years, of which 25% are fatal within 28 days.² The above statistics suggest that attention to secondary stroke prevention would be important in reducing the morbidity, mortality and cost to society of stroke. The purpose of this article is to review the role of anti-platelet and anticoagulant agents in the secondary prevention of stroke.

Goals of Therapy
Therapeutic measures in secondary stroke prevention aim to prevent recurrent stroke or transient ischemic attacks, with the aim of preventing morbidity and mortality from incremental neurological deficits, as well as preventing associated cardiac ischemic events.

Lilia Malkin, BSc

A global decline in stroke-related mortality occurred over the last two decades. Canada boasts one of the lowest rates in the developed world: "only" seven percent of its citizens' deaths are attributed to cerebrovascular disease (CVD). Advances in the medical management of stroke combined with health promotion and risk factor modification are being credited with dropping CVD death rates by decreasing stroke severity and incidence.¹ However, CVD-related morbidity remains an important issue for Canadian seniors, with CVD-related hospital admissions creeping upwards as this country's population ages.¹

Preventing the occurrence of the first stroke would not only contribute to decreasing CVD-related deaths, but would alleviate a tremendous burden of suffering by diminishing the stroke-associated morbidity. This article will focus on risk factors associated with CVD and strategies for primary stroke prevention.

Naushad Hirani BSc, MD

With the falling incidence of rheumatic fever in developed countries, the incidence of mitral stenosis has been steadily declining, although it remains one of the most common valvular lesions in developing nations. This lesion can present for the first time in elderly patients, as it often exists for many years before becoming clinically apparent. Knowledge of the etiology, pathogenesis, diagnosis, and treatment of this once common disease would be useful to any physician dealing with geriatric patients.

Etiology & Pathophysiology
The predominant cause of mitral stenosis (MS), as already alluded to above, is rheumatic fever, although there are several rare causes. Acute rheumatic fever itself is diagnosed using the Jones criteria, but often goes undiagnosed in young people. It is not therefore surprising that a reliable history is usually difficult to obtain and that the history is not the best guide as to the likelihood of the disease being present. The mechanisms by which the disease process is initiated remain controversial. It may be a slowly progressive autoimmune inflammatory reaction which begins with the illness and takes many years to become clinically significant, or it may be that the initial insult causes a deformity that with subsequent constant trauma due to turbulence leads to fibrosis, thickening, and calcification of the valve.

Elana Lavine, BSc

As the elderly population becomes an increasingly larger proportion of society, a key focus of scientific research will be the process of normal brain aging. Exactly what processes are considered to be a part of normal aging? Much of the literature examines the pathological changes observed in the brain of patients with such diseases as Alzheimer's and Parkinson's. However, the changes in brain morphology during senescence, as evidenced by studies of the healthy elderly, help shed light on what is truly attributable to aging and what is attributable to disease. The distinction between the two may be blurred by influences of lifestyle, such as diet and exercise. Individual variation in outcome measures, such as short-term memory, may create a wide range of what may be categorized as "normal" function. In addition, there exists a relative absence of neuropathological data from well-characterized healthy aged adults studied over extended periods of time.¹

Brain Size & Morphological Change
By 80 years of age, the average brain has decreased 15% in weight, and is noted as having smaller gyri, separated by wider sulci.² Specific research has focused on finding out exactly which parts of the human brain contribute to the decrease in weight. Supratentorial brain atrophy has been shown to progress with aging, and specifically with a reduction in the volume of gray matter.

Anna Liachenko, BSc, MSc

People with diabetes mellitus can have both acute and chronic complications from their disease. This article focuses on Hyperglycemic Hyperosmolar Non-Ketotic Syndrome (HHNS) and hypoglycemia, which are two important acute complications that occur in elderly diabetics.

Hyperglycemia
The key problem with diabetes is abnormal metabolism of carbohydrates leading to hyperglycemia. Blood glucose levels between 8 mmol/L and 10 mmol/L are sufficient to cause tissue damage but can be present in some patients without clinical symptoms for many years. This increases the risk of developing multiple long-term complications such as retinopathy, nephropathy and neuropathy.

During the life of a diabetic person, various factors may acutely raise hyperglycemia to symptomatic levels. These include high carbohydrate foods, stress, illness (usually infection), and medications (e.g. glucocorticoids, nicotinic acid, diuretics and phenytoin). If blood sugar rises above 10 mmol/L, it exceeds the renal reabsorption threshold and causes osmotic diuresis, resulting in loss of water and electrolytes (mainly sodium, potassium, phosphorus and magnesium). This creates a cycle of progressive hyperglycemia potentially having acute life-threatening consequences: diabetic ketoacidosis (DKA) or hyperglycemic hyperosmolar non-ketotic syndrome (HHNS). DKA occurs primarily in patients with Type 1 diabetes which tends to occur in younger patients.