Dosed physical load
The methodology of the work load
Before conducting a load test is necessary to evaluate the patient’s condition and to pay special attention to the following factors.
Complaints and anamnesis.
— The type, nature, duration and radiation of pain.
— Typical angina.
— Atypical pain in the chest.
— Associated symptoms.
Anamnestic indications of the presence of other diseases:
chronic lung disease;
neurological diseases, including cognitive disorders;
— The General level of physical activity.
— It is also recommended to spend a minimum of direct examination of the patient with the definition of heart rate and blood pressure, as well as to register the ECG alone.
Requested to explain to the patient the methodology of the study and to make necessary adjustments to the regime.
For 3 h before the examination the patient should not eat.
— If the patient smokes, he should refrain from Smoking for at least 3 h before the study.
— Within 12 hours before the study patient recommend performing unaccustomed or strenuous exercise.
For 48 h before the study should be abolished ?-blockers (except in those cases where the purpose of the study is to evaluate the effectiveness of antianginal therapy) and other prolonged antianginal drugs.
— It is recommended to bring a list of accepted medicines.
— You must bring light comfortable clothing and athletic shoes, and towel.
During the tests with dosed physical load pursue two main objectives:
— the determination of the tolerance of the patient to physical activity;
— identify clinical and electrocardiographic signs of myocardial ischemia due to coronary artery disease, to diagnose coronary heart disease.
During the exercise test monitoryou three main parameters:
— clinical response of the subject to physical stress (i.e. shortness of breath, dizziness, chest pain, development of typical angina, as well as the violation of the condition on a scale of Borg);
hemodynamic response (i.e., heart rate, blood pressure, double product, peak physical exertion);
— ECG changes during the test with physical load and during the recovery phase.
If you have the following baseline ECG changes the interpretation of the results of electrocardiographic exercise stress is almost impossible, and in these cases the conduct alternative tests :
— complete blockade of the left bundle branch;
— severe left ventricular hypertrophy;
— ST-segment depression greater than 1 mm;
— treatment with digoxin;
— EX-imposed ventricular rhythm.
For stress tests, regardless of the method of dosing load there are General principles:
— the uniformity of the load — load from one level to another should not be dispensed randomly and evenly to increase, to ensure the adaptation of the cardiovascular system at each stage that will allow for accurate diagnosis;
— fixed the duration of each stage; is worldwide accepted for the duration of the step load equal to 3 minutes;
— start the sample with the minimum load for Waimes is a value equal to 20-40 W, and for trademarkable — 1,8–2,0 METH (1 metabolic equivalent [MET] = 1.2 cal/min or 3.5 to 4.0 ml of oxygen consumed per minute per 1 kg of body weight).
The most common Protocol sample exercise using treadmill (Bruce Protocol) are presented in table. 6.
Table 6. The Bruce Protocol
In table. 7 shows the magnitude of maximum heart rate, depending on sex and age, at which to stop the test with load in healthy people.
Table 7. Maximum heart rate depending on age and sex
Calculation of maximum heart rate can be produced according to the formula:
Cssmax = 220–age (in years) for men;
Cssmax = 210–age (in years) for women.
In patients with an established diagnosis of ischemic heart disease are often limited to the achievement of the so-called submaximal heart rate, component 75-85% of max as well as a further increase in the load is dangerous because of the possibility of complications.
In table. 8 shows the magnitude of submaximal (75% of maximum) heart rate depending on age and sex.
Table 8. Submaximal heart rate depending on age and sex (75% of maximum)
Criteria adequate exercise test.
— Achievement 4-speed (13 MET).
— Achieving double the works of more than 20 000.
— Achieve 85% of maximum heart rate.
Normal electrocardiographic pattern:
the increase in the amplitude of teeth R;
decreasing the amplitude of teeth R;
reduction of point j;
angled Kosovskaya ST-segment depression;
the reduction of the Q–T interval;
decreasing the amplitude of the T wave
Clinical criteria for termination of exercise testing are
Absolute indications for termination sample:
— reduction of systolic BP ?10 mm Hg.PT. below the initial level, despite the increase in workload (if you have other signs of myocardial ischemia);
— the occurrence of angina of moderate or high intensity;
— the appearance of cerebral symptoms (ataxia, dizziness, syncope);
— signs of hypoperfusion (cyanosis or pallor);
— the failure of the patient to further test;
— technical problems.
Relative indications for termination sample:
— reduction of systolic BP ?10 mm Hg.PT. below the initial level, despite the increase in workload (in the absence of other signs of myocardial ischemia);
— increased chest pain;
— the sudden appearance of General weakness;
— the occurrence of severe shortness of breath;
— the emergence of pain in the calf or intermittent claudication;
— raising HELL over 250 and 115 mm Hg.PT.
Electrocardiographic criteria for termination of exercise testing are
Absolute indications for termination of the test:
— sustained ventricular tachycardia;
— ST-segment elevation ?1.0 mm in leads without teeth diagnostically relevant Q (except in leads V1 or aVR);
Relative indications for termination of exercise testing:
— change of the QRS complex and ST segment in the form of severe horizontal or conisholme ST more than 2.0 mm, or significant changes of the electrical axis of the heart;
— cardiac arrhythmias (except sustained ventricular tachycardia, including multifocal ventricular premature beats and triplets
ventricular extrasystole, supraventricular tachycardia, AV blockade and bradyarrhythmias;
— the emergence blockade feet beam Guisa or slowing of intracardiac conduction, morphology cannot be distinguished from ventricular tachycardia.