Cardiac Rehab - section 1 & 2

Cardiovascular Disease

Pathological process of atherosclerosis affecting the entire arterial circulation

includes: CAD, cerebrovascular disease, HTN, heart failure, and other conditions

Coronary Artery Disease

Atherosclerosis specific to the coronary arteries

includes diagnosis of angina pectoris, myocardial infarction, silent myocardial ischemia, and sudden cardiac death

Atherosclerosis

a disease which lipid-laden plaque (lesions) is formed within the intimal layer of the blood vessel wall of moderate- and large - size arteries

also, primary contributor to CVA and PVD → cerebrovascular disease

Cardiac Output

Amount of blood pumped through the ventricles per minute

Calculated as stroke volume X heart rate

Increases with exercise intensity due to increased heart rate

Stroke Volume

The volume of blood ejected with each contraction of the heart

Increases with minimal intensity and moderate intensity exercise

slight decrease with maximum intensity exercsie

Normal heart sounds

S1 - Mitral (and tricuspid) valve closing

S2 - Aortic (and pulmonic) valve closing

systole occurs between S1 and S2, diastole between S2 and S1

Abnormal heart sounds

S3 - heard in early diastole, associated with CHF

S4 - Heard in late diastole, associated with MI or hypertension

Effective contraction of the heart is dependent on…

depolarization and repolarization of the myocardium

P wave

Sinus node and atrial depolarization

PR segment

conduction through the AV node

QRS complex

electrical flow through ventricles→ ventricular depolarization

ST segment

Initiation of ventricular repolarization

T wave

completion of ventricular repolarization

Path of normal sinus rhythm

sinus node

atria

AV node

bundle of HIS

Purkinje fibers

septum

ventricles

myocardial oxygen supply depends on:

• delivery of oxygenated blood through coronary arteries (what pathological process would affect this)

• oxygen carrying capacity of the arterial blood (what two lab values will indicate what capacity is?

• ability of myocardial cells to extract oxygen from the arterial blood

myocardial oxygen demand (MVO2)

• MVO2 - HR x systolic BP

• an increase in systemic oxygen demand (exercise, fear, etc.) will increase MVO2

Hemoglobin levels

often compromised in patients with cardiovascular disease and must be checked prior to activity

• female: 12-16 g/dL

• male: 14-17 g/dL or 13-18 g/dL

Exercise recommendation for hemoglobin levels

< 7 g/dL: hold PT

7.1 - 7.9 g/dL clarify orders, monitor vitals, low level or essential ADLs only

8-10 essential ADLs, light aerobics or resistance

Potassium

3.5 - 5.0 mEq/L

Therapy recommendations for potassium

< 3 or >5 mEq/L: Hold PT

abnormal levels can cause cardiac arrythmias

Normal levels for Glucose

70-110 or 115 mg/dL

many patients with this disease also has CVD

Myocardial oxygen consumption (VO2max)

measurement of cardiorespiratory fitness

reflects the maximum amount of oxygen consumed per min when the individual has reached max effort

what are the 2 main factors that influence VO2 max?

cardiac output and arterial-venous difference (oxygen extraction of the perioheral muscle)

Metabolic Equivalent of Task (METs)

amount of oxygen consumed at rest per unit of body weight for one min (represents 1 single MET)

light intensity activity: less than 3 METs

moderate intensity activity: 3-6 METs

Vigorous intensity activity: over 6 METs

Effect of training on heart rate responses to graded exercises

As exercise continues, heart rate will gradually increase

an increase in oxygen uptake occurs with an increase in external workload

there is a direct relationship between heart and external workload

pulse grades

0 = absent → no perceptible pulse even with maximal pressure

1+ = thready → barely perceptible; easily obliterated with slight pressure; fades in and out

2+ = weak → difficult to palpate; slightly stronger than thready, can be obliterated with light pressure

3+ = normal → easy tp palpate; requires moderate pressure to obliterate

4+ = bounding → very strong; hyperactive; it is not obliterated with moderate pressure

cardiovascular responses to aerobic exercise - blood pressure

should be taken before and after exercise with patient in the same position

an increasing linear response is suspected in SBP

DBP may not change or may inc or dec by 10 mmHg

what are the indications of exercise intolerance that warrant modification or termination of an exercise session?

moderately severe or inc angina

marked dyspnea

dizziness, light headedness or ataxia

cyanosis or pallor

excessive fatigue

leg cramps or claudication

failure of systolic pressure to rise as exercise continues

hypertensive BP response

progressive fall in SBP of 10-15 mmHg

significant change in cardiac rhythm (palpations or ECG monitoring)

you may also need to terminate if pt responds in a way that is abnormal for them even if its not listed above

HTN

persistent elevation of >140/>90

some pt will have labile HTN that fluctuates b/w normal levels and hypertensive levels

exercise and BP

do not begin exercise without clearance from physician if their resting is >170-180/>90

you must always put BP measurements in context of the patient’s PMH and previous BP measurements

what is the clinical implication of labile HTN?