Eyes and the Heart
Heart disease, including heart attack, is the world's No. 1 killer. A person's risk of heart attack depends mostly on a familiar repertoire of factors: exercise, smoking, diet, weight, genes and lifestyle But our bodies' circadian rhythms also plays a role, leaving us more prone to injury during certain hours than others. If you are guessing that the danger zone comes at the end of a stressful workday, guess again.
The most dangerous times for heart attack and for all kinds of cardiovascular emergency - including sudden cardiac death, rupture or aneurysm of the aorta, pulmonary embolism and stroke - are the morning and during the last phase of sleep. A group from Harvard Medical School estimated this risk and evaluated that on average, the extra risk of having a myocardial infarction, or heart attack, between 6 a.m. and noon is about 40%. But if you calculate only the first three hours after waking, this relative risk is threefold.
The most dangerous times for heart attack and for all kinds of cardiovascular emergency - including sudden cardiac death, rupture or aneurysm of the aorta, pulmonary embolism and stroke - are the morning and during the last phase of sleep. A group from Harvard Medical School estimated this risk and evaluated that on average, the extra risk of having a myocardial infarction, or heart attack, between 6 a.m. and noon is about 40%. But if you calculate only the first three hours after waking, this relative risk is threefold.
The cardiovascular system follows a daily pattern that is oscillatory in nature: most cardiovascular functions exhibit circadian changes (circadian is from the Latin circa and diem, meaning "about one day"). Now, a heart attack depends on the imbalance between increased myocardial oxygen demand (i.e., a greater need for oxygen in your heart) and decreased myocardial oxygen supply - or both. And unfortunately, some functions in the first hours of the day require more myocardial oxygen support: waking and commencing physical activities, the peak of the adrenal hormone cortisol [which boosts blood-pressure and blood-sugar levels] and a further increase in blood pressure and heart rate due to catecholamines (adrenaline and noradrenaline), which show a peak when you wake up. All those factors lead to an increase of oxygen consumption but at the same time contribute to the constriction of vessels. So you have reduced vessel size and reduced blood flow to the coronary vessels.
You have to remember that blood coagulation is important in the genesis of what we call thrombi, the blood clots that can block the blood vessels and cut off supply to the heart. When we wake up, platelets, the particles in the blood that make thrombi, are particularly adhesive to the vessels. Usually we have an endogenous system - its called fibrinolysis - to dissolve the thrombi. But in the morning, the activity of our fibrinolytic system is reduced. So we have a greater tendency to make thrombi that can occlude the coronary vessels. This contributes to further reduction of coronary blood flow. Thus, at the same time that you need more blood flow, you have less.
All these changes, however, probably are not so harmful in healthy people. But for a person with a plaque in the coronary vessel, if these changes occur at the same time and peak at the same time, the final result is a higher risk of heart attack during that specific window of morning hours.
Why is the risk also higher during the last part of sleep? Usually, during the night, the cardiovascular system is "sleeping," which is characterized by low blood pressure and heart rate. But the last stage of sleep - REM, or rapid eye movement, sleep [when we believe most dreaming occurs] - is a risk period for cardiovascular emergencies because when you dream, you have a dramatic increase of activity of the autonomic nervous system - even more than when you are awake. Probably each of us can remember waking up in the morning sometimes feeling very tired. That is because during that stage of dreams, we were running or facing some danger. Your heart was running, so it was consuming oxygen. And for similar reasons to those when you are awake, that activity is risky if one does not have a good vessel system.
It's probably difficult for people to minimize the effects of their own biological rhythms. For example, you cannot avoid your morning risk by simply waking up later. Some researchers have tried an experimental model, in which people were instructed to stay in bed for four hours after they woke up before rising. But the same pattern simply occurred four hours after waking, because the risk is linked to our activities. We cannot be afraid of the catecholamines and the peak in blood pressure in the morning. It is a part of our physiology. And for healthy people, it is not a problem.
It's important for doctors, however, to remember this risk when they give therapy. Usually people take hypertensive drugs in the morning, when they wake up. But this is already the higher-risk period - so is the last hour of activity of the pill they have taken the day before [and not all pills give 24-hour coverage]. Doctors have to be sure that the pill they have prescribed is still active when patients need it most. It's not as easy as simply asking patients to take pills before bed instead of first thing in the morning, because during sleep we have a low heart rate and blood pressure. If you lower your blood pressure too much during the night, you risk reducing blood supply to the brain, and that can be harmful too. Because all of us are unique in many ways, please consult your Heart Physician and or Internist about any specific questions or concerns that you may have.
EYES AND HEART DISEASE
The eyes may carry important early clues to heart disease, signaling damage to tiny blood vessels long before symptoms start to show elsewhere, according to eminent researchers in Australia.
People with a type of eye damage known as retinopathy were more likely to die of heart disease over the next 12 years than those without it, according to the team at the University of Sydney and the University of Melbourne in Australia and the National University of Singapore.
They studied the retinal photographs of 3,000 people, most of whom had diabetes. Such snapshots are often taken to see if the diabetes has begun to damage the eyes. Then they checked records for deaths.
Over 12 years, 353 participants (11.9 percent) had coronary heart disease-related deaths," the researchers reported in the journal "Heart".
People with retinopathy were nearly twice as likely to die of heart disease as people without it, said the team, led by the University of Sydney's Dr.Gerald Liew.
Retinopathy raises the risk of heart disease as much as diabetes does. Diabetes is a well known risk factor for heart disease, the leading cause of death in most industrialized nations and many developing ones.
People with these changes may be getting a first warning signal that damage is occurring in their arteries, and should strive to lower cholesterol and blood pressure, the researchers said.
METABOLIC SYNDROME:
The symptoms that constitute the "metabolic syndrome" put individuals at high risk for Heart Attack, Diabetes and Stroke. Smoking and excessive alcohol consumption are additional risk factors.
Other risk factors include:
The eyes may carry important early clues to heart disease, signaling damage to tiny blood vessels long before symptoms start to show elsewhere, according to eminent researchers in Australia.
People with a type of eye damage known as retinopathy were more likely to die of heart disease over the next 12 years than those without it, according to the team at the University of Sydney and the University of Melbourne in Australia and the National University of Singapore.
They studied the retinal photographs of 3,000 people, most of whom had diabetes. Such snapshots are often taken to see if the diabetes has begun to damage the eyes. Then they checked records for deaths.
Over 12 years, 353 participants (11.9 percent) had coronary heart disease-related deaths," the researchers reported in the journal "Heart".
People with retinopathy were nearly twice as likely to die of heart disease as people without it, said the team, led by the University of Sydney's Dr.Gerald Liew.
Retinopathy raises the risk of heart disease as much as diabetes does. Diabetes is a well known risk factor for heart disease, the leading cause of death in most industrialized nations and many developing ones.
People with these changes may be getting a first warning signal that damage is occurring in their arteries, and should strive to lower cholesterol and blood pressure, the researchers said.
METABOLIC SYNDROME:
The symptoms that constitute the "metabolic syndrome" put individuals at high risk for Heart Attack, Diabetes and Stroke. Smoking and excessive alcohol consumption are additional risk factors.
Other risk factors include:
- Waist greater than 40" for men and 35" for women,
- Blood Pressure greater than 140/90 mm hg,
- Fasting Glucose greater than 110mg/dl,
- Triglycerides greater than 150mg/dl,
- LDL cholesterol in excess of 100 mg/dl, and
- HDL Cholesterol lower than 40 mg/dl.