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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