Progress in cardiovascular diseases
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Prog Cardiovasc Dis · Jul 2010
Historical ArticleThe contribution of the Framingham Heart Study to the prevention of cardiovascular disease: a global perspective.
The Framingham Heart Study has been a trailblazer in the field of cardiovascular epidemiology. The wealth of novel scientific data that it has generated over 5 decades has made a significant contribution to cardiovascular disease (CVD) prevention in the United States and indirectly influenced global CVD prevention strategies. The Framingham Study has provided insights into the prevalence, incidence, prognosis, predisposing factors, and determinants of CVD. ⋯ When these findings were first published, these were novel cardiovascular risk factors, now they are the major focus for global and national prevention efforts for reducing the burden of CVD and other major noncommunicable diseases. The Framingham Heart Study has also been in the forefront of the development of cardiovascular risk prediction equations for assessment of absolute risk. Further developments in this area including the development of World Health Organization/International Society of Hypertension risk prediction charts have resulted in a paradigm shift in CVD prevention strategies, from a single risk factor focus to a more cost-effective total cardiovascular risk approach, an approach recommended by the World Health Organization for CVD prevention worldwide.
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The Framingham Heart Study remains the most famous and influential investigation in cardiovascular disease epidemiology. To generations of epidemiologists, it is a model for the cohort design. Here we revisit the origins of the Framingham Study before it became an accomplished and famous investigation whose existence and success are taken for granted. ⋯ Epidemiology was primarily focused on infectious disorders. Framingham's pioneers struggled to invent an appropriate epidemiological approach to this chronic disease and to establish support for a new kind of research within a community. Thereafter they had to convince skeptical medical professionals that the results of epidemiological investigations of heart disease were applicable to their clinical practices.
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Chronic Mountain Sickness (CMS) is an important high-altitude (HA) pathology in most mountainous regions of the world. Although its most characteristic sign is excessive erytrocytosis (EE), in the more severe stages of the disease, high-altitude pulmonary hypertension (HAPH), with remodeling of pulmonary arterioles and right ventricular enlargement is commonly found. The degree of ventricular hypertrophy depends on the vasoconstrictor pulmonary response, the intensity of vascular resistance and the level of altitude, and therefore on the degree of hypoxemia. ⋯ Although CMS individuals have a less effective vasoconstrictor reflex, their tolerance to orthostatic stress is similar to that of healthy HA natives which might be explained in terms of the larger blood volume present in CMS subjects. At present research is directed to design strategies on pharmacological intervention for CMS treatment. Recently, a clinical trial with acetazolamide, in patients with CMS has proven to be effective in increasing mean pulmonary acceleration time and decreasing pulmonary vascular resistance index, which might be indirectly due the reduction of hematocrit.
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Prog Cardiovasc Dis · May 2010
Physiological adaptation of the cardiovascular system to high altitude.
Altitude exposure is associated with major changes in cardiovascular function. The initial cardiovascular response to altitude is characterized by an increase in cardiac output with tachycardia, no change in stroke volume, whereas blood pressure may temporarily be slightly increased. After a few days of acclimatization, cardiac output returns to normal, but heart rate remains increased, so that stroke volume is decreased. ⋯ However, there has been recent suggestion that 10% to 25% of the loss in aerobic exercise capacity at high altitudes can be restored by specific pulmonary vasodilating interventions. Whether this is explained by an improved maximum flow output by an unloaded right ventricle remains to be confirmed. Altitude exposure carries no identified risk of myocardial ischemia in healthy subjects but has to be considered as a potential stress in patients with previous cardiovascular conditions.
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Prog Cardiovasc Dis · Mar 2010
ReviewReducing population salt intake worldwide: from evidence to implementation.
Raised blood pressure is a major cause of cardiovascular disease, responsible for 62% of stroke and 49% of coronary heart disease. There is overwhelming evidence that dietary salt is the major cause of raised blood pressure and that a reduction in salt intake lowers blood pressure, thereby, reducing blood pressure-related diseases. Several lines of evidence including ecological, population, and prospective cohort studies, as well as outcome trials, demonstrate that a reduction in salt intake is related to a lower risk of cardiovascular disease. ⋯ Several countries have already reduced salt intake. The challenge now is to spread this out to all other countries. A modest reduction in population salt intake worldwide will result in a major improvement in public health.