Coffee and your heart rhyhtm

March 23, 2010 by  
Filed under HEART AND STROKE

Over the years, a lot of research studies have been conducted to assess the effect of caffeine on heart health. This is a highly relevant topic considering that

  • Coffee is one of the most popular drinks in the world, hot or cold.
  • Energy drink consumption which contains high amounts of caffeine has become a very popular soft drink among the young and even used as performance enhancer.

Many of those studies report inconclusive or contradictory results about the effect of caffeine on heart health.

A latest research study at Kaiser Permanente Division of Research, Oakland, CA explored the common belief that coffee causes palpitations, e.g. irregularity in the heartbeat when the heart literally “skips a beat.”

According to Dr Arthur Klatsky, who is leading the study:

“A lot of people think they have palpitations from coffee, and doctors commonly tell people not to drink it, but there are very few actual data, and the data that are available suggest no relationship. We went into this study thinking there would be no association, but to our surprise, there was actually an inverse relationship. It could be protective, although one observational study doesn’t prove anything yet.”

The researchers looked at 130,054 members of the Kaisers Permanente health plan and asked them to complete questionnaires on coffee drinking habits and other lifestyle factors.

The study results indicate that coffee consumption is associated with a lower risk for hospitalizations for arrhythmia (irregular heartbeat). In addition, the effect seems to be additive, e.g. the more coffee you drink, the lesser is the risk. As an example, those who drink more than 4 cups of coffee per day have an 18% less likelihood to have arrhythmia-induced hospitalization. The effect of caffeine consumption did not vary regardless of gender, ethnicity and smoking habits.

Is it really the caffeine?

Well, those who drank only decaf coffee did not have this protective effect so the evidence points to caffeine as the protective substance. However, the authors are quick to point out that coffee” is a complex substance and that it includes other ingredients that might be at work, including antioxidants, in reducing the risk of arrhythmias” which might have been drastically reduced during the decaffeinating process.

So what does caffeine do?

Dr. Klatsky and colleagues say the mechanisms behind the cardioprotective properties of caffeine are not fully understood but it may have something to do with caffeine competing with the compound adenosine in the brain. They speculate that the same competition might occur in the heart where adenosine is involved in the conduction and recovery of heart muscle cells after depolarization. However, more studies are needed to confirm these findings, including studies that will look into incidence of less sever arrhythmias that do not result in hospitalization.

However, the authors think it might be tricky to find subjects willing to cooperate with such studies.

It might be a little tricky to get people to give up their coffee, and for those who aren’t coffee drinkers, it might be tough to get them to start drinking four cups per day.”

Either you are a coffee drinker or you are not. I’m partial to lattes and mochas myself. Which one are you?

Do anti-depressants make the heart stop?

July 21, 2009 by  
Filed under DEPRESSION

pills-blue

Sudden cardiac death or sudden cardiac arrest (SCA) has gained worldwide attention because of Michael Jackson’s passing last month. To review some SCA statistics from the Sudden Cardiac Arrest Coalition:

As I’ve posted before, there are many things that can interfere with the heart’s electric system, leading to a full stop and death. A recent study by researchers at Columbia University indicates that depression – and the use of anti-depressants  – can also cause SCA. And it’s not about overdose on anti-depressants, but regular use at normally prescribed dosage.

The study followed up 63,469 women who were participants in the Nurses’ Health Study and who did not have a history of cardiovascular disease or any other life-threatening disorders. The participants were monitored for depressive symptoms and anti-depressant use for eight years. The study results confirmed what previous studies have reported: Depressive symptoms were significantly associated with cardiac events, and especially strongest with fatal events.

However, what is new is the fact that the use of antidepressants to manage the depressive symptoms does not actually lower the risk for cardiac events but rather increases the risk of SCA. According to the present study

“61% of subjects were using selective serotonin-reuptake inhibitors (SSRIs), while 39% used other, nonspecified antidepressants.”

It is not clear how these medications exactly can affect heart function but researchers believe it has something to be with triggering arrhythmia or irregular heart rhythms. A previous study has linked antidepressant use to increased high blood pressure.

The authors warn that more study is needed to confirm the antidepressant use – SCA link.

“It is unclear whether SSRI agents might cause [sudden cardiac arrest]. While cardiac events are well documented with . . . tricyclic antidepressants, evidence for a link with SSRIs is mixed… Moreover, it is quite possible that antidepressant use merely indicates that depression is of sufficient severity to merit treatment.”

There have been high profile deaths due to SCA mainly because of the widespread use of prescription drugs among celebrities as a means of coping with their stressful, high-flying lifestyles. Among these prescription drugs are sleeping pills, anti-depressants, and pain killers.

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How anger affects your heart rhythm

May 7, 2009 by  
Filed under HEART AND STROKE

Some more indication that anger and negative feelings have adverse effects icdon heart health. Researchers from Yale University followed 62 patients who were equipped with implantable cardioverter-defibrillators (ICDs). These patients were suffering from coronary artery disease or dilated cardiomyopathy that made them to wear ICDs.  An ICD is a battery-operated implantable device that detects abnormal heart rhythms (arrhythmias). Once arrhythmia is detected, it applies a corresponding electrical jolt to restore the rhythm back to normal.

According to Arrhythmia Alliance, a UK-based charity organization, most modern ICDs function in 3 ways:

If your heart rhythm is too slow, the device can give your heart extra beats by working as a normal pacemaker. This is called anti-bradycardia pacing

If your heart beats too fast, the ICD can give you a burst of extra beats at an even faster rate which will normally return your heart back to a normal rhythm. This is called anti-tachycardia pacing (or ATP)

If the anti-tachycardia pacing doesn’t bring your heart back to a normal rhythm, or if the ICD senses a faster rhythm called ventricular fibrillation, the ICD can then give a higher energy shock. This is called defibrillation

The patients in the current study were asked to undergo a mental stress test by recalling a recent situation or incident wherein they were angry or aggravated. The T-wave alternans (TWA) of the patients were measured during the recollection. TWA is a measure of the electrical stability of the heart. Long term follow up consisted of monitoring for a mean of 37 months which patients had arrhythmias that required termination by the ICD.

According to Dr. Rachel Lampert, associate professor at Yale University School of Medicine “It’s an important study because we are beginning to understand how anger and other types of mental stress can trigger potentially lethal ventricular arrhythmias, especially among patients with structural heart abnormalities… We know strong emotion increases sympathetic arousal. In this study, we found patients with higher levels of anger-induced TWA were more likely to experience arrhythmias requiring ICD termination.”

It seems that patients with higher TWA induced by anger and strong negative emotions were predisposed to arrhythmias. Arrhythmias are irregularities in heart rhythms that can lead to sudden cardiac death.

In current study, 16% of patients with ICD-terminated arrhythmias during the follow up period had higher TWA induced by anger compared with those patients who did not have arrhythmias. Anger-induced TWA was a significant predictor of arrhythmias that led to a ten-fold increased risk compared to patients with normal TWA.

How TWA relates to heart rhythm irregularities is not so clear. Unlike physical exercise, mental stress due to anger does not increase heart rate. This suggests that TWA changes associated with mental stress “may be due to a direct effect of adrenaline on the heart cells.”

A previous post touched on the effect of negative emotions on heart health. Anger and hostility were associated with a 19% increase in coronary heart disease (CHD) events in healthy individuals and a 24% increase in risk among those with pre-existing CHD.

Truly, there is a need to consider anger management and other behavioural interventions an essential part of heart disease prevention and management.

Coming next: tips on anger management.

July Resource Post: The Athlete’s Heart

August 24, 2008 by  
Filed under HEART AND STROKE

The heart and physical exercise

What happens to the heart during exercise? A lot of things go faster – breathing rate, heart rate, blood flow. Now, imagine an endurance athlete such as a marathon runner, a Tour de France cyclist, an Iron Man triathelete. Their body and their heart perform faster – for hours and hours almost non-stop.

This introduction to cardiac output by the Montana State University explains what is happening to an athlete’s heart during a competition.

Cardiac output (in liters) is the total blood volume pumped by the heart’s ventricle each minute and is calculated as the heart rate (beats per minute) and stroke volume (mL of blood). Below is a table where the performance of a heart at rest and during a cross country competition is compared.

 

Heart at rest

Non-athlete heart during normal exercise

Athlete heart during cross-country competition

Heart rate (beats per minute)

80

180

approx. 190

Stroke volume (mL)

60 to 80

70

210

Cardiac output (L)

4.8 to 6.4

12.6

40

Source: Montana State University; BBC

The blood pumped by the heart is distributed to different organs in the body. When resting, only 15% of cardiac output goes to the muscles. The highest proportion goes to the liver (about 27%) and the kidney (about 22%). During a cross-country skiing competition, the muscles require 60 to 70% of cardiac output, followed by the skin (about 15%) while the requirements for the kidneys and the liver drop below 10%.

The heart of a trained athlete

When the heart performs at top speed regularly such as that of an athlete, the volume of its chambers become larger, the cardiac output also increases. Thus, based on the numbers in the table above, a trained athlete’s heart during a cross-country competition performs almost 8 times more than what a normal does at rest about 3 times more than a non-athlete doing exercise.

Although the numbers will vary from sport to sport and from individual athlete to individual athlete, it is clear from the figures above that a lot of physiological changes occur during physical exercise. Marathon running, cycling, and triathlon are among the most physically demanding sports. Cycling competitions like Tour de France are especially challenging because the event goes on for days with barely time for the cyclists to recover.

The benefits of exercise

We’ve always thought that athletes are the healthiest people on earth. After all, the benefits of exercise are quite well-known (see previous post) for young and old alike, as follows:

  • Lowers blood pressure
  • Strengthens the heart
  • Strengthens the bones
  • Prevents disability
  • Prolongs life

Lack of exercise on the other hand, is a major risk factor for cardiovascular disorders, diabetes, and osteoporosis among others. The fact that many athletes suddenly collapse and die of cardiac events at their prime during sports events is incomprehensible to us.

Recent research on the athlete’s heart

Studies by Belgian cardiologists show that endurance sports may trigger abnormal heart rhythms (arrhythmias) among athletes, even those without cardiomyopathy. Furthermore, these arrhythmias are not necessarily benign but can lead to more serious heart conditions.

In a first study [1], 46 high-level endurance athletes, mostly cyclists, with ventricular arrhythmia (VA) were monitored for a median of 4.7 years. Over the follow up period, a large number of the athletes developed more serious heart conditions, 18 developed a major arrhythmic event that resulted in 9 deaths. The study concludes that

complex ventricular arrhythmias do not necessarily represent a benign finding in endurance athletes. ..Endurance athletes with arrhythmias have a high prevalence of right ventricular structural and/or arrhythmic involvement. Endurance sports seems to be related to the development and/or progression of the underlying arrhythmogenic substrate.

The second study [2] looked at 22 endurance athletes diagnosed with VA, 15 athletes without VA, and 10 non-athletes without VA as control. Their results show clear differences between athletic and non-athletic hearts. In addition, the condition of VA frequently start as a mild abnormality in the right ventricle that, with prolonged performance of endurance sports, can promote ventricular changes and trigger arrhythmias.

The sudden death of athlete has always been thought to be due to pre-existing conditions such as hypertrophic cardiomyopathy or right ventricular dysplasia. Many of these conditions are genetically determined, thus, the American Heart Association strongly recommends a close look at an athlete’s family history to determine his or her risk.

There is strong indication that excessive physical exercise is linked to potentially dangerous irregular heart rhythms. The studies above report about “acquired right ventricular dysplasia” among endurance athletes that may potentially lead to atrial fribrillation and sudden death. Thus, a trained athlete’s heart may actually become a health hazard rather than the fountain of youth.

Like many things in life, too much of a good thing can be bad. It seems that this also applies to exercise.

As this editorial in the European Heart Journal [3] states:

“…athlete’s heart is a well-known consequence of sport practice, and has been considered as a kind of physiological adaptation to extreme training. It was not until very recently that athlete’s heart (dilatation, hypertrophy and enhanced vagal tone) was recognized as a possible risk factor for the development of atrial fibrillation,establishing a link between excessive training and the presence of arrhythmias.”

 

References:

  1. Heidbüchel et al. High prevalence of right ventricular involvement in endurance athletes with ventricular arrhythmias. Role of an electrophysiologic study in risk stratification. Eur Heart J. 2003 Aug;24(16):1473-80.
  2. Ector et al. Reduced right ventricular ejection fraction in endurance athletes presenting with ventricular arrhythmias: a quantitative angiographic assessment. Eur Heart J. 2007 Feb;28(3):345-53.
  3. Lluís Mont and Josep Brugada. Endurance athletes: exploring the limits and beyond. Eur Heart J 2003 24(16):1469-1470.

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cross-country skiing

cycling 2

marathon

Getting back to rhythm: The latest on atrial fibrillation

June 16, 2008 by  
Filed under HEART AND STROKE

We have all heard and used the idioms “my heart is racing”and “my heart missed a beat”. However, they are not just figures of speech. They happen literally  – with a condition called atrial fibrillation or AF for short.

The general term for irregular heartbeat is arrhythmia and AF is the most common form of arrhythmia in the United States, according to a recent review in the ScienceDaily. A normal adult heart at rest beats around 50 to 100 beats per minute. A heart with AF beats much faster and very irregularly, making it “race” and “miss a beat.”

According to Eric Good, an AF specialist and assistant professor of cardiovascular medicine at the University of Michigan Medical School, “atrial fibrillation is a chaotic, electrical rhythm that begins in the top chamber of the heart, called the atrium…It involves impulses that whirl around the top chamber, traveling at speeds of 400 to 600 beats per minute in a type of electrical storm that can bombard the lower chambers with rapid signals and result in a very irregular and fast heart beat.

What makes AF dangerous is that they act like “lightning bolts” in the heart to cause blood clots. These clots can be carried away by the blood, escape from the heart and get lodged in some blood vessels. Clots which block blood vessels to the brain can lead to stroke.

In the US, one in every 5 strokes is due to AF and the numbers are increasing.

The link between [AF] and stroke is so tight that it is crucial that patients work with their doctor to discuss the treatment options,” according to Lewis Morgenstern, director of the University of Michigan Stroke Program. “There is a lot that can be done, particularly at a center such as ours with specially trained stroke specialists from neurology, cardiology and many other fields.”

In order to avert stroke, the irregular heart pattern needs to be corrected. Several treatments are available to control AF, from blood-thinning medications to avoid blood clots to pacemakers to radiofrequency (RF) ablation.

In RF ablation, catheters are inserted via the veins in the groins to the left atrium of the heart. Through the catheter, the heart is “zapped” to restore the heart rhythm back to normal.

New investigative devices to control AF are currently being tested at the University of Michigan Medical School and are described below.

The Watchman device is “designed to keep clots from forming in a small area of the heart that’s called the left atrial appendage – a “sock” off to the side of the atrium. The appendage seems to serve little purpose, and yet it’s the birthplace of more than 90 percent of clots that form in the heart.” It is inserted via a catheter like RF ablation.

Another device is a special balloon-camera that “looks” inside the heart and with a minute laser, it zaps the heart muscle. Like RF ablation, this zapping creates small scars on the muscles that stop the chaotic impulses from getting through.

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Know your drugs: smoke cessation drug varenicline causes psychosis, arrhythmia

June 11, 2008 by  
Filed under HEART AND STROKE

Last May 21, the US Federal Aviation Administration (FAA), the government agency that is in charge of civil aviation safety issued a ban on the use of the smoking cessation drug varenicline by airline pilots and air traffic controllers, as reported by the New York Times.

The following day, on May 22, the US Federal Motor Carrier Safety Administration, the agency in charge of safety in the interstate trucking and bus industry also issued the ban for bus and truck drivers.

According to an FAA spokesman, about 150 pilots and 30 air-traffic controllers were on varenicline with permission from FAA but they have been told on May 21 to discontinue taking the drug and to stay away from work for 72 hours until the effects of the drug have subsided.

Earlier this year, the FDA issued a warning against varenicline due to undesirable side effects, which includes

Varenicline, marketed as Chantix in the US by Pfizer, comes in the form of pills. Several clinical studies have shown that the drug help smokers quit. It works by partly blocking and partly stimulating a nicotine receptor in the brain. Chantix was approved for market in the US and the European Union in 2006. It is estimated that 6.5 million people have used or are using it, translating to $883 million in sales last year.

The first publicized undesirable side effects of varenicline were reported last year when “a Dallas musician, Jeffrey Carter Albrecht, was shot to death after he began behaving bizarrely while taking Chantix.” Since then, several cases of suicides and psychotic behaviour have been associated with the use of varenicline.

A study conducted by the Institute for Safe Medication Practices (ISMP) reported many of the adverse events listed above. Aside from the psychological disturbances, it seems that varenicline is also potentially proarrhythmic, that is, it causes irregularity in heart rhythms which can be potentially lethal and can lead to heart attacks. People with heart conditions are therefore advised against the use of varenicline.

Aside from pilots and drivers, ISMP also recommends that persons operating highly sensitive machinery and devices such as nuclear power reactors, high-rise construction cranes or life-sustaining medical devices should also be banned from using varenicline.

Smoking causes deaths mainly by causing cancer and cardiovascular disorders. The use of smoking-cessation drugs has become popular in recent years as more and more people are realizing the health benefits of quitting. It is most unfortunate that varenicline, which seems to help people quit smoking, may actually bring more harm than benefit to its users.

However, other options are such as nicotine replacement remedies in the form of patches and gums are available.

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NOTE: The contents in this blog are for informational purposes only, and should not be construed as medical advice, diagnosis, treatment or a substitute for professional care. Always seek the advice of your physician or other qualified health professional before making changes to any existing treatment or program. Some of the information presented in this blog may already be out of date.