Heart Rates: Why are they important to know?

 There are many things that can affect the heart rate and are important to consider if you are a heart patient. Heart rate vary as the body’s need to absorb oxygen and excrete carbon dioxide changes, such as during, exercise or physical activity, sleep or illness. The normal human heart rate is between 60-80 beats per minute at rest.

 

Slow Heart rates

Exercise implications of a low heart rate can indicate a problem when the heart rate does not increase sufficiently with exertion, creating increased fatigue, shortness of breath, exercise intolerance, or EKG changes.  It is important  for heart patients to observe how the heart rate responds to exercise. Does it increase and by how much? 

Medications known as beta blockers frequently lower resting heart rates to upper 40-60 range. That isn’t always considered a problem. If there are no symptoms of compromise such as shortness of breath, chest discomfort, fainting, overwhelming fatigue or cognitive changes and the treatment is tolerated, there is not usually concern. When the rates start to get into the low 40’s there is  more concern. When you sleep the heart rate usually drops another 10 beats per minute, and heart rates in the 30’s are not able to adequately get enough circulating oxygen in the bloodstream to nourish the organs. You might not notice it thus might be found in sleep studies, or if on remote monitoring with holter monitor studies.

If you are on beta blockers the the heart rates are quiet a bit lower than traditional heart rate posters. Many people  on beta blockers have a very blunted heart rate response to activity. On beta blockers your heart rate ranges are usually set 10-20 points lower than the traditional age predicted heart rate ranges or are often prescribed at 50 -70% of age predicted values (see chart below). This doesn’t mean you don’t get the benefits from exercise. The benefits are not directly linked to the heart rates. Exercise conditions the muscles to be efficient at utilizing the oxygenated blood and  thus takes demand off the heart to work harder to provide the blood flow to the working muscle. So the heart doesn’t have to pump as fast.  Think of the muscles as a secondary pump that extracts the oxygen and pushes the blood back to the lungs for re oxygenation.

Commonly prescribed Beta Blockers are usedd to treat the following conditions

• HTN  is Hyperension
• Angina =Chest Discomfort
• Arrhy=arrhythmia or irregular heart rhythm
• MI = Myocardial Infarction meaning heart attack
• CHF = Congestive Heart Failure – Shortness of breath and fluid retention in abdomen, legs, weakness of the heart, low ejection fraction

• Acebutolol -Sectral
• Atenolol – Tenormin
• Betaxolol – Kerlone
• Bisoprolol – Zebeta, also sold as Ziac
• Carteolol -Cartrol
• Carvedilol -Coreg
• Labetalol – Normodyne, also sold as Trandate
• Metoprolol – Lopressor, also sold as Toprol
• Nadolol – Corgard
• Penbutolol – Levatol
• Propranolol – Inderal, Inderal LA
• Timolol – Blocadren

This is a question for you and your healthcare professional. What should my target heart rate range be at given my being on beta blockers? It is up to you to determine how you will measure and track your rates. Here are some methods and tools to monitor. 

 

 

To monitor the heart rate you should  measure the rate for 60 second to determine the rate. It is also useful to note if it is regular. Fitness plays a role here. The more fit you are the lower the resting heart rate. If the heart is efficient and the muscle are strong there is less demand for the heart to go faster to meet the supply and demand of the muscles. Most symptoms of this are shortness of breath, fatigue, exercise intolerance. Then exercise is progressed more on tolerance than by the goal of getting the heart rate elevated to a higher percentage but a rate between 50 and 85% of age predicted target heart rate range.

Exercise  elevates the heart rate. How high is too high?

Most frequently the Karvonen target heart rate is method to determine the age adjusted threshold which is 220  – minus age = Maximal Heart Rate range at which one should not try to achieve when exercising a heart that has had  cardiovascular health issues. A percentage between these ranges is often prescribed by your healthcare practitioner. It is a range!!!! Not an I have to hit the top of this to benefit my heart range. The goal is to be somewhere in that range, we all have good days and bad especially when struggling with heart issues.

If you are in the low end of the range that is just as good as the upper end when it comes to exercise, and there are times when the upper range is too high and it is better to be in the lower range. Again there is an art versus  science of target heart rate ranges the best advise is  be active at a level for which you are  free of symptoms, yet the effort feels fairly light to somewhat hard and does not feel physically hard to perform for several minutes.

Some heart patients  may find a fast resting heart rate if medications are off, or if complications are developing such as the heart rhythm abnormalities or changes.  If the rate is faster than normal and in the recommended exercise levels when resting do not exercise instead contact your healthcare provider ASAP. 

Wall motion, blood pressure, heart rhythm, exercise intolerance, pacemaker or ICD programming must be discussed to really understand the extent of your target heart rates for exercise. Because of such complexity, initially starting to increase activity on a regular basis that elevates the heart rates some and remaining free of symptoms, being able to talk while exercising is an important assessment tool of how well one is tolerating exercise. Make sure to include this discussion at your cardiology or primary care appointment. Discuss safe heart rate ranges for activity, and how your medications and heart condition will influence it. What are your medical concerns?  Heart patients are not instructed to exercise at age predicted maximum heart rate ranges.

Below  is a standard chart your healthcare staff  uses to prescribes a ranges for safe activity. For heart patients there may be ranges where there are ischemic changes meaning there is a change in the EKG noted while in  Cardiac Rehabilitation or with stress testing. Theoretically one could monitor their own  for issues through use of the new Ipod apps for heart rhythm monitoring, or small handheld electronic devices like those shown above. Most exercise is initially prescribed light following a heart issue and gradually increased to meet daily living needs including work, physical, and activity/exercise needs.

Age	Maximum HR	50 percent	75 percent	85 percent
20	200	100	150	170
25	195	98	146	166
30	190	95	142	161
35	185	93	138	157
40	180	90	135	153
45	175	88	131	149
50	170	85	127	144
55	165	83	123	140
60	160	80	120	136
65	155	78	116	132
70	150	75	113	127
75	145	72	108	123
80	140	70	104	119
85	135	68	101	115

If you have cardiovascular issues such as  angina, poor heart wall motion due to the injury to the heart  from a heart attack or cardiomopathy, inadequate blood pressure responses, EKG electrical changes, then the target heart rate ranges are established by your physician to a safe level. This target heart rate range is your individual level based on your medications, your heart issues, and your fitness goals.

Most rehabilitation of the heart is done in lighter zones initially, then progresses gradually too higher heart rates to meet daily living needs including work, physical, and activity/exercise needs. Many are able to do high levels of physical exertion when trained including returning to jogging, cross country skiing, or strenuous job requirements. Rehabilitation programs are beginning to work select patients to higher target heart rate ranges with interval training. Sometimes the art of exercise prescription outweighs the science of it when balancing a complex medical history of cardiovascular disease.