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CARDIAC SYSTEM

37

The procedure is also used in the following diagnostic and therapeutic techniques!2:

• Angiography

• Percutaneous transluminal coronary angioplasty (PTCA)

• Electrophysiologic studies (EI'Ss)

• Cardiac muscle biopsy

Right-sided catheterization involves entry through a sheath that is

inserted into a vein (commonly subclavian) for evaluation of right

heart pressures; calculation of CO; and angiography of the right

atrium, right ventricle, tricllspid valve, pulmonic valve, and pulmonary artery. 12 It is also used for cominuous hemodynamic monitoring in patients with present or very recent heart failure to monitor cardiac

pressures (see Appendix III-A). Indications for right heart catheterization include an intracardiac shunt (blood flow between right and left arria or right and left ventricles), myocardial dysfunction, pericardial

constriction, pulmonary vascular disease, valvular heart disease, and

status post-heart transplam.

Left-sided catheterization involves entry through a sheath that is

inserted into an artery (commonly femoral) to evaluate the aorta,

left atrium, and left ventricle; left ventricular function; mitral and

aortic valve function; and angiography of coronary arteries. Indications for left heart catheterization include aortic dissection, atypical angina, cardiomyopathy, congenital heart disease, coronary artery

disease, status post MI, valvular heart disease, and status post heart

transplant.

Clinical Tip

• After catheterization, the patient is on bed rest for

approximately 4-6 hours when venous access is performed

or for 6-8 hours when arterial access is performed.12

• The sheaths are typically removed from the vessel 4-6

hours after the procedure, and pressure is applied constantly for 20 minutes following sheath removal.'2

• The extremity should remain immobile with a sandbag

over the access site to provide constant pressure to reduce

the risk of vascular complications. 11

38

ACun CARE HANDBOOK FOR PHYSICAL THERAPISTS

•

Some hospitals may use a knee immobilizer to assist

with immobilizing the lower extremity.

•

Physical therapy intervention should be deferred or limited to bedside treatment within the limitations of these

precautions.

•

During the precautionary period, physical therapy

intervention, such as bronchopulmonary hygiene or education, may be necessary. Bronchopulmonary hygiene is

indicated if there are pulmonary complications or if risk of

these complications exists. Education is warranted when

the patient is anxious and needs to have questions

answered regarding his or her functional mobility.

• After the precautionary period, normal mobility can

progress to the limit of the patient's cardiopulmonary

impairments; however, the catheterization results should

be incorporated into the physical therapy treatment plan.

Angiography

Angiography involves the injection of radiopaque contrast material

through a catheter to visualize vessels or chambers. Different techniques are used for different assessments12: Aortography is used to assess the aorta and aortic valve. Coronary arteriography is used ro

assess the coronary arteries. Pulmonary' angiography is used to assess

the pulmonary circulation. Ve/ltriculography is used to assess the

right or left ventricle and AV valves.

Elecrrophysiologic Studies

EPSs are performed to evaluate the electrical conduction system of the

hearr. '2 An electrode catheter is inserted through the femoral vein

into the right ventricle apex. Continuous ECG monitoring is performed both internally and externally. The electrode can deliver programmed electrical stimulation to evaluate conduction pathways, formation of arrhyrhmias, and the automaticity and refractoriness of

cardiac muscle cells. EPSs evaluare the effectiveness of antiarrhyrhmic

medication and can provide specific information about each segment

of the conduction system.'2 [n many hospitals, these studies may be

combined with a therapeutic procedure, such as an ablation procedure (discussed later in this chapter, in the Management section). Indications for EPSs include the followingl2:

CARDiAC SYSTEM

39

• Sinus node disorders

• AV or intraventricular block

•

Previous cardiac arrest

• Tachycardia at greater than 200 bpm

• Unexplained syncope

Clinical Tip

Patients undergoing EPS should remain on bed reSt for 4--6

hours after the test.

Pathophysiology

When disease and degenerative changes impair the heart's capaciry to

perform work, a reduction in CO occurs. If cardiac, renal, or central

nervous system perfusion is reduced, a vicious cycle resulting in heart

failure can ensue. A variety of pathologic processes can impair the

heart's capaciry to perform work. These pathologic processes can be

divided into four major categories: ( 1 ) myocardial ischemia and

infarction, (2) rhythm and conduction disturbance, (3) valvular heart

disease, and (4) myocardial and pericardial heart disease. CHF occurs

when this failure to pump blood results in an increase in rhe fluid in

the lungs, liver, subcutaneous tissues, and serous cavities.s

Myocardial Ischemia a1!d l1!farctio1!

When myocardial oxygen demand is higher than supply, the myocardium must use anaerobic metabolism to meet energy demands. This system can be maintained for only a short period of time before tissue

ischemia will occur, which typically results in angina (chest pain). If

the supply and demand are not balanced by rest, medical management, surgical intervention, or any combination of these, injury of the myocardial tissue will ensue, followed by infarction (cell death). This

balance of supply and demand is achieved in individuals with normal

coronary circulation; however, it is compromised in individuals with

40 AClTfE CARE HANDBOOK FOR PHYSICAL THERAPISTS

impaired coronary blood flow. The following pathologies can result in

myocardial ischemia:

• Coronary arterial spasm is a disorder of transient spasm of coronary vessels that impairs blood flow to the myocardium. It can occur with or without the presence of atherosclerotic coronary disease, It results in variant angina (Prinzmeral's angina), 12

• Coronary atherosclerotic disease (CAD) is a multistep process

of the deposition of fatty streaks or plaques on artery walls

(atherosis). The presence of these deposits eventually leads to artetial wall damage and platelet and macrophage aggregation that then leads to thrombus formation and hardening of the arterial

walls (sclerosis). The net effect is a narrowing of coronary walls. It

can result in stable or unstable angina (UA), or MI.'·5.I'

Clinical syndromes caused by these pathologies are the foliowing7,I':

Stable (exertional) angina occurs with increased myocardial demand,

such as during exercise, is relieved by reducing exercise intensity or terminating exercise, and responds well to nitroglycerin. Variant angina (Prinzmetal's angina) is a less-common form of angina caused by coronary artery spasm. This form of angina tends to be prolonged, severe, and not readily relieved by nitroglycerin.

UA is considered intermediate in severity between stable angina

and MI. It usually has a sudden onset, occurs at rest or with activity

below the patient'S usual ischemic baseline, and may be different from

the patient'S usual anginal pattern. It is not induced by activity or

increased myocardial demand thar cannor be mer. Ir can be induced ar

rest, when supply is cut down with no change in demand, A common

cause of UA is believed ro be a rupture of an arherosclerotic plaque.

M! occurs with prolonged or unmanaged ischemia. It is important

to realize that there is an evolution from ischemia to infarction.

Ischemia is rhe first phase of rissue response when the myocardium is

deprived of oxygen. It is reversible if sufficient oxygen is provided in

time. However, if oxygen deprivation continues, myocardial cells will

become injured and eventually will die (infarcr). The locarion and

extent of cell dearh are derermined by rhe coronary artery rhar is compromised and rhe amount of rime that rhe cells are deprived. Refer to Table 1 - 1 3 for common types of M1 and rheir complicarions. Figure