interven-tions in cardiology continue to expand. The more common ones encountered by physical therapists are described briefly in the fol-lowing pages.
MEDICAL MANAGEMENT
Generally speaking, most types of cardiac dysfunction are treated medically for as long as possible, using pharmacologic agents, diet modification, risk factor reduction, rehabilitation, and other inter-ventions. When symptoms become disabling, surgery may be warranted.
Pharmacologic Therapy
The various medications used to treat cardiovascular dysfunction are described in Chapter 5 (Pharmacology).
Diet Modification
Specific diet modifications may be advised for patients with cardio-vascular disease.
• A low-cholesterol, low saturated fat diet is usually recommended for patients with known atherosclerotic cardiovascular disease and those at high risk for its development. In addition, the American Heart Association has issued preventative dietary guidelines for healthy adults that emphasize the importance of a healthy diet that is low in saturated fat and trans-fat, and rich in fruits, vegetables, whole grains, fat-free and low-fat dairy pro-ducts, and lean meat, fish, and poultry. These guidelines also address appropriate body weight and desirable blood pressure.
• High-fiber intake (25 to 35 g/d) is recommended for the pre-vention of atherosclerosis as well as colon cancer.
• Sodium restriction is often used to reduce preload in heart fail-ure (along with fluid restriction to avoid hyponatremia) and to lower blood pressure in hypertension.
• Caloric restriction is usually recommended to achieve weight loss in overweight and obese individuals, reduce the workload of the heart for those with heart failure, and decrease blood pressure in hypertensive individuals.
• Because of the extended contact we have with patients, physi-cal therapists are in an ideal position to reinforce the impor-tance of diet modification and share the findings of current literature and good low-fat, low-cholesterol foods and recipes with our patients.
Risk Factor Reduction
Because the atherosclerotic process has been linked to specific risk factors, their reduction is often recommended for patients with atherosclerotic coronary, cerebrovascular, and peripheral vascular disease.
• Risk factor reduction includes cessation of smoking, treatment of hypertension, exercise training, diet modification, weight control, stress reduction training, and control of blood glucose levels.
• There is a great deal of scientific data to support risk factor reduction both for primary prevention of atherosclerotic dis-ease as well as for secondary prevention of recurrent events.4,11,19,28
• As physical therapists practice more independently, we have an increasing responsibility to assess the overall health status of the patients we treat and make appropriate recommendations for their general health and well-being. Risk factor reduction for cardiovascular disease, the leading cause of death in the United States, is a critical element.
Cardiac Rehabilitation
Cardiac rehabilitation (CR) is a multidisciplinary program aimed at restoring the cardiac patient to optimal physiologic, social, vocational, and emotional status. It usually includes patient assess-ment, case manageassess-ment, and the development of an individua-lized treatment plan, patient and family education, risk factor modification, exercise training, psychological counseling, and patient reassessments to document progress.5 A great deal of research has documented that optimal reduction of coronary risk factors results in stabilization and possibly regression of the athero-sclerotic process.11,19In patients with CAD, CR, particularly exercise CHAPTER 3 44 Cardiovascular Medicine 59
training, has demonstrated favorable effects on plasma lipids, fasting glucose levels, body composition, peak aerobic capacity, depression, and quality of life.4,27In patients receiving CR after heart transplanta-tion and heart valve surgery and for chronic heart failure, demon-strated benefits include increased functional capacity, favorable modification of disease-related risk factors, amelioration of symptoms, identification of signs and symptoms of disease before they become serious complications, and improved quality of life.18,25,28,29
Because physical therapists have unequaled expertise in pre-scribing exercise, especially for patients with chronic medical pro-blems, and in the prevention and treatment of exercise-related injuries, we are assets to the cardiac rehabilitation team.
Enhanced Extracorporeal Counterpulsation Enhanced extracorporeal counterpulsation (EECP) is a noninvasive technique involving the sequential inflation of pressure cuffs applied to the lower extremities, which gently compresses the veins to assist blood return to the heart during diastole. EECP results is increased preload, decreased afterload, and improved cor-onary perfusion pressure during diastole. It is performed over a series of several weeks in patients with myocardial ischemia to improve the balance between myocardial oxygen supply and demand and thus relieve chest pain and in patients with heart fail-ure to improve LV function and exercise tolerance.
Cardiopulmonary Resuscitation
Physical therapists are required to be trained in cardiopulmonary resuscitation (CPR) in the event that a patient experiences cardiac arrest. The goal is to support a small amount of blood flow to the heart and brain to “buy time” until normal heart function is restored. Frequently, cardiac arrest is due to ventricular fibrillation (see page 272), which requires the delivery of an electrical shock (i.e., defibrillation) to restore normal rhythm. The availability of small portable defibrillators, called automated external defibrilla-tors (AEDs), has improved the ability to provide rapid defibrillation in many medical buildings and public places.
Cough CPR
A coughing procedure widely publicized on the Internet, cough CPR involves the use of repeated forceful coughing when a con-scious, responsive person experiences a sudden arrhythmia. The theory is that it may maintain enough blood flow to the brain to allow the person to remain conscious for a few seconds until the arrhythmia disappears or is treated. In the hospital setting, it is used mainly during cardiac catheterization.
Cardioversion and Defibrillation
Direct current (DC) electrical energy is used to correct serious tachyarrhythmias and ventricular fibrillation.
• Cardioversion is used to treat hemodynamically significant tachyarrhythmias (see page 113) that are refractory to medica-tions or to convert atrial fibrillation to normal sinus rhythm.
The patient must be connected to an electrocardiogram (ECG) so the electrical shock can be synchronized with the R wave to avoid delivery during the T wave, which can induce ventricular fibrillation (VF). It is often performed as an elective procedure with patients under general anesthesia or sedation.
• Defibrillation is used emergently to treat patients with VF or pulseless ventricular tachycardia. The electrical discharge is used to overwhelm and suppress chaotic ectopic impulses so the intrinsic conduction system can take over. Automatic exter-nal defibrillators (AEDs) can be found in most physical therapy departments and many public facilities to allow immediate resuscitation of individuals who collapse with cardiac arrest.
SURGICAL INTERVENTIONS
A variety of surgical interventions are used in the treatment of patients with heart disease, many of which are described briefly in the following pages.
Myocardial Revascularization
Several procedures exist to increase myocardial blood flow through stenotic coronary arteries. These include a number of catheter-based percutaneous techniques as well as surgical revascularization via coronary artery bypass grafting (CABG) or transmyocardial revascularization.
Percutaneous Transluminal Coronary Angioplasty
During percutaneous transluminal coronary angioplasty (PTCA), a balloon-tip catheter is passed through the femoral artery, up the aorta, and then into a diseased coronary artery, using fluoroscopic guidance. The balloon is positioned across a stenotic lesion and inflated. The goal is to increase the intraluminal diameter by frac-turing the plaque and disrupting the vessel intima, as illustrated in Figure 3-25.
Figure 3-25: Likely mechanism of balloon dilation in percutaneous transluminal coronary angioplasty (PTCA). Serial panels show the baseline stenosis (A), passage of the deflated balloon catheter (B), balloon inflation (C), and the postdilation appearance (D), as drawn in longitudinal and transverse cross-sectional views.
Note fracture and outward displacement of atherosclerotic plaque and stretching of the media and adventitia (C and D). (From Castaneda-Zuniga WR, Formanek A, Tadavarthy M, et al. The mechanism of balloon angioplasty. Radiology. 1980;135:565–571.) 60 CARDIOVASCULAR AND PULMONARY PHYSICAL THERAPY
Restenosis occurs in 10% to 50% of patients undergoing PTCA, usually within the first 6 months; therefore, about 70% to 90% of PTCAs also involve placement of a stent (see the next section).
Percutaneous transluminal angioplasty can also be applied to the renal, mesenteric, and peripheral arteries and to diseased saphenous vein coronary artery bypass grafts.
Intracoronary Stents
Coronary stents are intraluminal metallic mesh tubes (Figure 3-26), which are usually inserted after PTCA via a balloon-tipped catheter in order to maintain vessel patency. Simple stents decrease the rate of restenosis to approximately 20%, and newer drug-eluting stents that provide for the local delivery of immunosuppressive or antipro-liferative agents slash the restenosis rate to approximately 5%; how-ever, there have been some reports of a small increase in risk of late stent thrombosis associated with the use of these stents. Another treatment option that reduces restenosis within stents by approxi-mately 50% is intravascular radiation therapy (brachytherapy), using radioactiveg- or b-emitters.
Atherectomy
Atherectomy involves the insertion of intracoronary catheters with special tips that shave, grind, or slice the atherosclerotic plaque within a coronary artery, somewhat like a little “Roto-Rooter” or
“Pac Man” with suction. It is usually combined with PTCA in order to increase lumen size.
Laser Angioplasty
In laser angioplasty, a catheter with a laser at its tip is inserted into a coronary artery and advanced to a blockage, where it emits pul-sating beams of light in order to vaporize the plaque. This proce-dure may be used alone or with balloon angioplasty.
Coronary Artery Bypass Graft Surgery
Coronary artery bypass graft (CABG) surgery, also referred to as aorto-coronary bypass (ACB) surgery, uses autogenous saphenous vein or arterial grafts (usually the internal thoracic/mammary artery or occasionally the radial or gastroepiploic artery) to bypass stenotic lesions of the coronary arteries. Figure 3-27 shows the common types of bypass grafts. Multiple lesions in the same coro-nary artery can be bypassed by sequential grafting, particularly when an internal thoracic artery graft is used.
• CABG is performed primarily via a median sternotomy, and at closing, the sternum is wired back together again.
4 Immediately after surgery, the patient commonly has two chest tubes in place: one to drain the mediastinum and an intrapleural tube to reinflate the left lung, which was collapsed during sur-gery (see Chapter 2, page 32, for information related to chest tubes and their implications for physical therapy).
4 Reasonable healing of the sternum usually takes approxi-mately 6 to 8 weeks. Although there are no controlled studies documenting their efficacy, sternal precautions related to the amount of weight patients are allowed to lift are commonly prescribed during this interim period to avoid excessive ster-nal stress; the amount of restriction and the time period vary widely from surgeon to surgeon but normally fall in the range of not more than 10 to 20 pounds for 6 to 12 weeks. Patients are also restricted for 3 to 4 months, or more, from doing pushups and other strenuous resistive exercises that involve the pectoralis muscles. Furthermore, most physicians require modifications of assisted transfers and ambulation with a walker or crutches to minimize sternal stress.
• Although CABG is usually performed while the patient is sup-ported by extracorporeal cardiopulmonary bypass (CPB), some centers use beating heart or off-pump coronary artery bypass (OPCAB) when only one or two grafts are needed, particularly in elderly patients and patients with calcified ascending aortas, carotid disease, or previous stroke or coronary artery bypass grafting.
Unexpanded stent Expanded stent
Figure 3-26: An intracoronary stent before inflation and in its expanded configuration, used to maintain the patency of a vessel after PTCA.
Figure 3-27: Coronary artery (CA) bypass graft surgery showing a reverse saphenous vein graft from the ascending aorta to the right CA (a), an in situ left internal mammary artery graft to the left anterior descending CA (b), a Y-graft of the right internal mammary artery from the left internal mammary artery to the circumflex CA (c), a radial artery graft from the aorta to the cir-cumflex CA (d), and an in situ gastroepiploic graft to the posterior descending branch of the right CA (e). (From Goldman L, Ausiello D. Cecil Textbook of Medicine. 23rd ed. Philadelphia: Saunders;
2008.)
CHAPTER 3 44 Cardiovascular Medicine 61
• An alternative to standard CABG via sternotomy is minimally invasive direct coronary artery bypass surgery (MIDCAB), which is performed endoscopically and off-pump through a combination of small holes in the chest and a small incision made directly over the coronary artery to be bypassed. In this method the internal thoracic artery is often employed to bypass the left anterior descending (LAD) coronary artery. During port-access coronary artery bypass (PACAB or PortCAB), the patient is placed on CPB and the heart is stopped while bypasses are performed endoscopically through small ports or incisions. Computer, or robotic, enhancement of minimally invasive techniques is also possible using totally endoscopic, robot-assisted coronary artery bypass grafting (TECAB).
Besides the sternotomy precautions mentioned previously, there are other implications pertaining to physical therapy treatment of patients who have undergone CABG surgery:
• During the immediate postoperative period, arrhythmias are not uncommon and usually do not cause hemodynamic compro-mise; however, clinical monitoring of the patient’s HR, BP, and any signs of exercise intolerance should be performed to detect any serious problems (see Chapter 6, pages 261, 278, and 282).
• Patients should be encouraged to maintain full range of motion of their shoulders, trunk, and neck and to practice good pos-ture, and they should be discouraged from crossing their legs when they sit, especially if saphenous vein grafts were harvested.
• In addition, cardiac rehabilitation with exercise training is important for these patients, both to increase exercise toler-ance and to reduce the rate of atherogenesis and restenosis in their bypass grafts.
Hybrid Revascularization
For patients with complex lesions not fully amenable to any of the aforementioned approaches, both percutaneous coronary interven-tion and minimally invasive CABG surgery can be performed dur-ing the same procedure. Typically, it consists of anastomosis of the left internal mammary artery (LIMA) to the LAD artery with stent-ing of the right coronary and/or circumflex arteries.
Transmyocardial Revascularization
For patients with severe angina who are not candidates for other treatment options, transmyocardial revascularization (TMR) can be used to increase blood flow to the myocardium. TMR is usu-ally performed through a small incision in the left chest, through which the surgeon uses a laser to drill a series of holes from the outside of the heart into the LV. Pressure from the surgeon’s fin-gers is sufficient to stop the epicardial bleeding from the laser channels within a few minutes. The mechanism by which TMR reduces angina is not fully understood, but may be due to stimu-lation of new blood vessel growth (angiogenesis) by the laser and destruction of sympathetic nerve fibers so the patient simply no longer feels his chest pain. A worldwide registry of more than 3000 patients treated with TMR found that 80% show improve-ment in angina class and 30% had no angina a 1-year follow-up.16 Other studies report reductions in cardiac events and rehospitalization as well as improved exercise tolerance and qual-ity of life.2
Treatment of Arrhythmias Cardiac Ablation
Cardiac, or catheter, ablation involves the use of energy to destroy (ablate) areas of endocardium that are related to the onset or main-tenance of tachyarrhythmias. It is used in patients with supraven-tricular tachycardia, atrial flutter or fibrillation, and vensupraven-tricular tachycardia with focal sources of the arrhythmia or an accessory pathway that perpetuates it, as identified through an EPS. It is typi-cally performed in patients with tachyarrhythmias that cannot be controlled with medication or who cannot tolerate or prefer not to take antiarrhythmic medications and has very high success rates.
• Radiofrequency ablation causes resistive heating in cells near the catheter tip, resulting in irreversible damage and tissue death.
• Cryoablation uses nitrous oxide delivered to the catheter tip to cause tissue damage by freezing the nearby cells.
• Chemical ablation with alcohol or phenol may be performed in patients who fail other ablation procedures or when other approaches cannot be done.
Pacemaker Insertion
Pacemakers are electronic devices that use an external energy source to stimulate the heart when disorders of impulse formation and/or transmission create significant hemodynamic problems.
They are surgically implanted, usually in the left infraclavicular area, as depicted in Figure 3-28; in a subxiphoid pocket; or in the left anterior chest wall.
• Modern pacemakers have a variety of functions, which can be programmed according to patient need. Pacemaker modes and functions are described according to an established five-letter code, described in Table 3-6.
4 The first letter designates the chamber being paced (A for atrium, V for ventricle, and D for dual-chamber).
Figure 3-28: The most common site of implantation of a permanent pacemaker is the left pectoral region, but it may be placed elsewhere if necessary. (From Forbes CD, Jackson WF.
Color Atlas and Text of Clinical Medicine. 3rd ed. Philadelphia:
Mosby; 2003.) 62 CARDIOVASCULAR AND PULMONARY PHYSICAL THERAPY
4 The second letter indicates the chamber being sensed (A, V, D, or O for no sensing).
4 The third letter specifies the response to sensing: I if the sensed signal inhibits pacemaker discharge, or T if the sensed signal triggers pacemaker discharge, D if both functions are available, or O for none.
4 The fourth letter refers to the programmability of the pacemaker for rate modulation independent of atrial activity (R) or not (O) (see later section on rate-responsive pacemakers).
4 The fifth letter indicates multisite pacing in none of the chambers (O), one or both of the atria (A), one or both of the ventricles (V), or any combination of A and V (D).
• There are several types of pacemakers, the most common of which are briefly described here. In addition, the pacemaker modes recommended by the British Pacing and Electrophysiol-ogy Group (now Heart Rhythm UK, London, UK) for various conduction disturbances are listed in Table 3-7.
4 Dual-chamber pacemakers have the ability to sense both the atrium and the ventricle, or just the ventricle, and to pace both the atrium and the ventricle, or just the ventricle, according to specific need. They can be programmed to either inhibit or trigger a discharge.
8 DDD pacemakers provide optimal sequential pacing because they sense and pace both the atrium and the ventri-cle and adapt to the underlying rhythm automatically, according to a specific scheme, to either inhibit or trigger a
discharge as needed; they are best for patients with both sinus and AV nodal dysfunction, providing AV synchrony.
8 VDD devices are designed for patients with AV block and normal sinus node function, sensing both the atrium and ventricle and providing a ventricular stimulus when an excessive delay occurs after a spontaneous atrial discharge.
8 DDI pacemakers sense and pace both the atrium and the ventricle, inhibiting pacemaker discharge when spontaneous activity is sensed.
8 DVI devices pace both the atrium and the ventricle while sensing only the ventricle. This mode is rarely used because the asynchronous atrial pacing it produces can precipitate atrial fibrillation.
8 Mode switching allows dual-chamber pacemakers to change the pacing mode automatically and reversibly to elim-inate atrial sensing during atrial fibrillation and flutter or other supraventricular tachyarrhythmias (i.e., they change to VVI, VDI, or DDI mode).
4 Single-chamber pacemakers are demand pacemakers, which sense and pace either the atrium or ventricle.
8 VVI pacemakers deliver automatic pacing of the ventricles unless spontaneous ventricular activity is sensed. Because this type of pacing disturbs normal atrioventricular synchrony, it is used only for patients with chronic atrial fibrillation or flutter.
8 AAI pacemakers provide automatic pacing of the atrium
8 AAI pacemakers provide automatic pacing of the atrium