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Exercise following mechanical heart valve replacement

1. Effects of physical training on the cardiovascular system

Physical exercise following mechanical heart valve replacement is nowadays one of the pillars of long-term therapy and should form a regular part of the patient’s daily or weekly routine. Long-term studies have shown that even heart valve patients can achieve the same level of fitness following surgery as that enjoyed by healthy persons of the same age.

Any pre-existing heart damage is a crucial factor in the fitness prognosis. As a rule of thumb one can say: the longer the condition has pre-existed and the more complex the pre-existing damage is, the longer it will take to restore fitness.

Cardiological sports medicine has long taken an interest in the effects of physical training on diseased and post-surgical heart muscle.

The following effects have been scientifically proven:

reduction in the heart rate at rest and under stress,

reduction in the systolic blood pressure peak under stress,

lower rate of pressurization during the blood expulsion phase from the ventricle,

long diastolic duration,

greater elasticity of all the blood vessels,

thickening of the vascular endothelium,

lower tendency for the platelets (thrombocytes) to aggregate,

lower tendency for the red blood cells (erythrocytes) to agglutinate,

improved fibrinolysis.

This means that the blood’s flow properties are improved, the heart muscle pumps with less pressure, and resistance due to friction in the blood vessels and in the new heart valve is considerably reduced.

These primary effects are important for the heart valve patient.

 

2. Devising a training program

Devising an optimum training program requires the data used as the basis for the cardiological diagnosis. The correct training program depends on:

pre-existing damage,

the surgical outcome,

healing of the heart muscle,

any secondary cardiological conditions,

the stress ECG and

echo cardiography data (the pumping action of the heart chambers).

The optimum training program is as follows:

a) It should involve endurance-type exercise (walking, hiking, running, cycling, ergometer training, swimming, ski tours, inline skating).

b) It should be pursued daily, at least 3-4 times per week, for longer than 30 minutes each time.

c) In intensity it should not exceed 65% of maximum physical performance.

Ad a): Endurance-type exercise has the most beneficial effects on the cardiovascular system, the blood picture and metabolism, as it involves alternate contraction and relaxation of the muscles. This guarantees optimum blood supply with only moderate rises in blood pressure.

Ad b): A training program for the cardiovascular system and blood picture should last longer than 30 minutes, as it should allow all of the metabolic systems to be included in the energy-providing process, fat metabolism being one of the main systems.

Ad c): The intensity should not exceed 65% of maximum physical performance. The training should be aerobic. Up to this intensity the muscles burn fats along with carbohydrates while binding oxygen. The lactic acid and adrenalin concentrations remain low, this being easy on the blood picture. If the muscle becomes over-acidified through anaerobic work, a high level of adrenalin builds up owing to the presence of lactic acid in the blood. This acidic metabolic environment makes the blood thicker and less receptive to oxygen. Over-acidification occurs at an intensity of approximately 65% of maximum physical performance. As the intensity of exercise increases, there is no further optimization of training effect.

 

3. Calculation of optimum intensity from the stress ECG

To calculate the optimum intensity, take the last wattage on the stress ECG as being 100%. Calculate 65% of this to obtain the training wattage. Then check the stress ECG records to see what heart rate was entered for this stage. This gives the optimum training heart rate. This should not be exceeded during exercise. Although the heart muscle will not be damaged if you briefly exceed these values, the conditions will no longer be optimum for the blood picture.

Example: You reach 100 watts as the highest stage in the stress ECG. Your optimum training intensity would then be 65 watts (= 65%).

If, however, there are other cardiological reasons why this training wattage cannot be maintained (e.g. too great a rise in blood pressure, limited pumping action, stress-related arrhythmias, etc.), then the intensity of the exercise must be reduced.

 

4. Rating different types of exercise

Cardiological sports medicine differentiates between volume load and pressure load when judging different types of exercise.

Volume load is when the heart muscle is working at a high heart rate (pulse frequency) but with only a small rise in blood pressure.

Pressure load is when the heart muscle is working at a low heart rate but with a high blood pressure. For this reason, types of exercise with a predominantly volume load are to be preferred.

Exercise with pure volume load are rated as optimal:

walking, speed-walking,

hiking, jogging,

ski tours, inline skating,

(all on the level).

Exercise with gentle pressure load, rated as very good:

walking, speed walking, hiking, jogging, ski tours, inline skating with slight differences in altitude,

ergometer training, cycling on the level, swimming, cross-country skiing, golf.

Exercise with moderate pressure load is rated as good:

cycling with moderate differences in altitude,

ski tours with moderate differences in altitude,

rowing tours, kayak tours, canoe tours (depending on water and current conditions),

dancing.

 

Exercise with moderate to intense pressure load rating are considered satisfactory:

skittles, 10-pin bowling,

tennis (depending on the strength of the opponent),

sailing (depending on the class of boat and wind strength),

volleyball, badminton, family tennis,

Alpine skiing,

mountain biking with large differences in altitude.

In all these types of exercise the load depends on the skill level of the participant.

 

Types of exercise with a high pressure load rating are considered bad:

power sports (weightlifting, power training with heavy weights),

squash, badminton at a competitive level,

wind-surfing,

football, handball.

Looking at the last two groups in detail, it is clear how difficult it can be to give a rating. The pressure load, for instance, depends on how good one is at a certain sport.

There must always, therefore, be in-depth individual counselling with an experienced cardiological sports instructor and a cardiologist.

Special case – swimming and diving:

These two types of sport have been very controversial over the last 20 years for heart valve patients, the reason being that in earlier investigations cardiac arrhythmias were observed above and below water. Furthermore, blood moves from the legs to the abdomen and chest owing to the hydrostatic pressure, causing the pressure in the lungs to rise slightly.

Nowadays we know that the aquatic milieu does not pose any risk to the heart muscle. Patients can train according to the same criteria (heart rate) as on land.

In addition, it has been found that patients with restricted cardiac function and/or atrial fibrillation do not tend to have increased cardiac arrythmias in water so that, as long as the training recommendations are followed, swimming is allowed for anyone who enjoys the sport and can reach a swimming pool without any difficulty.

The optimum water temperature is between 24 and 32°C.

Diving without equipment (holding the breath under water with simultaneous additional workload) gives rise to extremely high pressures in the lung combined with an oxygen deficit, as regular breathing in and out is not possible. Staying under water for less than 20 seconds does not cause any problems.

The fitness studio

Time and again the question is raised concerning the medical value of power training in a fitness studio. Basically, it can be said that power training in order to stabilize the muscle substance and joint function is becoming increasingly important in medical rehabilitation. More recent investigations show that power training has a very beneficial effect in helping with everyday workloads.

Its earlier rejection by cardiologists was due to the unpredictable and poorly measurable peaks of blood pressure that occurred, which they suspected would damage the heart muscle. Following replacement heart valve surgery, it was feared, there would be considerable pressure at the site where the valve was attached to the aortic arch.

Investigations in the last 7 years have shown that moderate stamina training with weights of up to 50% of the maximum performance of the relevant muscle group pose no risk. The problematic blood pressure peaks occur at workloads of 65% to 80% of maximum muscle power, after more than 15 repetitions, or with a workload duration of more than 20 seconds. Short-term maximum exertion for less than 4 seconds is unproblematic, as measured on a power machine using a right-heart catheter.

Nowadays modern fitness studios offer very good, individually tailored exercise programs. Ask the studio about staff qualifications and their seal of quality.

Spending time at altitude

Here are a few tips on spending time at altitude, whether for a longish vacation or to enjoy winter sports.

As altitude increases, so the oxygen pressure in respired air gradually decreases, meaning that the body is able to absorb less oxygen with each breath. The body responds with faster breathing and an increase of up to 20% in heart rate compared to the resting value. Consequently, your usual training pulse rate is already reached with what would appear to be only a slight workload. A further negative effect is the increasing viscosity of the blood as, at altitude, the body also loses more fluid via the respiratory system. You must ensure that your liquid intake is adequate.

These changes only occur at more than 2000 metres, so that time spent at this altitude under a physical workload (skiing, ski tours, mountain hiking or cycling) is unproblematic.

Altitude acclimatization takes approximately two to three days. Do not start your training program, therefore, until you have been at that altitude for two days.

Spending time in tropical climates

Please note that in Mediterranean or tropical regions you should not undertake intense physical training at a temperature of more than 28°C and a humidity of more than 80%, as the body can no longer keep up the necessary heat regulation.

Here again, the resting heart rate is already raised and the training heart rate reached much sooner than expected.

Sauna/Turkish bath

There is no risk in using a sauna. In a sauna the heat causes the heart rate to rise sharply in order to transport the blood to the periphery. There the heat is returned to the environment. The arterial blood pressure drops slightly. However, avoid ice-cold dips. Take a cold shower instead.

 

5. Taking Exercise at the onset of cardiac insufficiency or limited pump function.

Calculating the optimum training intensity when there are secondary heart conditions (e.g. hypertension, coronary heart disease) is in itself problematic. If, in addition, cardiac insufficiency or severely limited pump function of the left heart is present, training targets must be redefined.

If the left ventricle is unable to pump enough blood into the vascular system to cope with the workload, then the load must not be maintained for any length of time.

Patients with these conditions were for a long time considered to be untrainable and were excluded from sporting activities.

In recent years a new training program aimed at maintaining muscle power has been developed for this clinical picture. The term used is interval training, i.e. the workload must not be sustained for longer than 20 to 30 seconds, and a pause of 40 to 60 seconds must follow.

Interval training is best performed on an exercise bicycle. Pedal for 20 seconds and pause for 40 seconds, or pedal for 30 seconds and pause for 60 seconds.

The wattage depends on the cardiological diagnosis.

Training targets can also be achieved with small dumb-bells or other strength-building equipment.

Devising this type of training program is extremely complicated and should only be undertaken by clinically experienced cardiological sports instructors.

 

6. Are there any differences between aortic and mitral valve patients?

The same principles are applied to both groups when the training program is being worked out. The same test results used for the cardiological diagnosis are used for the training program, irrespective of whether the replacement heart valve is a mechanical or biological one.

Long-term results indicate that aortic valve patients without any secondary conditions who have undergone right-heart surgery achieve the best training effect. There is practically no limitation with regard to the exercise workload and they can achieve very high levels of fitness.

Patients who have replacement mitral valves and atrial fibrillation do not notice any rise in performance in the first few months, as the fibrillation stops the training program being intensified. The body needs much longer for the heart muscle to heal.

 

7. Summary

Replacement heart valve patients can be trained at any phase following their operation. The program of exercise therapy is much more variable than is the case with myocardial infarction and bypass patients. With a good surgical outcome and the exclusion of other cardiological conditions, there is virtually no limit to the physical workload that the body can cope with.

The prescribed program of exercise is governed by the cardiological diagnosis and should nevertheless still be properly discussed with cardiological exercise therapists in the hospital or outpatient heart clinic.

Author: Uwe Schwan, Graduate Sports Instructor, Clinic Bad Hermansborn, Bad Driburg (Germany)