Chapter Chronic Heart Failure Keteyian C H A P T E R

Definition The inability of the left ventricle (LV) to pump blood at a level that is commensurate with metabolic needs; can be due to a failure of either systolic or diastolic function. –Systolic dysfunction—the inability of cardiac myofibrils to contract or shorten against a load –Diastolic dysfunction—an abnormal increase in resistance to filling of the LV

Scope Approximately 5.7 million people are afflicted. CHF is the leading reason for hospitalizations in people 65+ yr of age and directly or indirectly contributes to 283,000 deaths annually. Among people >45 yr of age, approximately 670,000 new cases are identified each year. 65

Pathophysiology Characteristics unique to HFREF/HFPEF: 1.An ejection fraction that is reduced (systolic) or unchanged or slightly increased (diastolic) at rest 2.An increase in LV mass, with end-diastolic and end-systolic volumes that are increased (systolic failure) or decreased (diastolic failure) 3.Edema or fluid retention because of elevation of diastolic filling pressures or activation of the renin–angiotensin– aldosterone system, causing sodium retention 4.More so with systolic (vs. diastolic) heart failure, an imbalance of the autonomic nervous system such that parasympathetic activity is inhibited and sympathetic activity is increased (continued)

Table 14.1

Pathophysiology (continued) Additional characteristics unique to HFREF/HFPEF: These are other abnormalities of hormones and chemicals that contribute to adverse cardiac and vascular remodeling or function and changes within and around the skeletal muscles: –Increased release of brain naturetic peptide (BNP) –Diminished production of nitrous oxide (endothelium-derived relaxing factor) –Increased endothelin-1 and increased cytokines (e.g., tumor necrosis factor-alpha) Substantial clinical evidence now indicates that many of these factors contribute to the remodeling of the LV, reshaping it from a more elliptical form to a spherical form. This change in shape or geometry itself contributes to a further loss in LV systolic function.

Figure 14.1

Clinical Considerations Exercise testing provides important information about the patient’s functional status, but signs, symptoms, and medications must also be considered. Relevant signs and symptoms include: –Change in fatigue level or dyspnea Paroxysmal nocturnal dyspnea Orthopnea Dyspnea on exertion –Fluid retention manifested by peripheral edema or meaningful weight gain

Physical Examination Evaluate/grade peripheral edema; pitting edema present? Pulmonary congestion, evidenced by rales Abnormal heart sounds; S 3 and/or S 4 gallop Abnormal breathing sounds

Testing for Diagnosis and Prognosis Echocardiogram –Radionuclide test or cardiac catheterization Graded exercise test with measured gas exchange –VO 2 peak –Ventilatory efficiency (V E -VCO 2 ) BNP levels (>100 mg/dl can be a sensitive index of decompensated HF)...

Cardiopulmonary Exercise Test See figure 14.2 for an example of a patient ready to undergo a cardiopulmonary exercise test, often used to estimate prognosis in patients with chronic heart failure.

Figure 14.3

Categorizing Patients’ Clinical Status Based on Stage of HF See table 14.2, “Stages in the Development of Heart Failure: ACC/AHA Guidelines (2009).”

Treatment Lifestyle changes –Risk factor management (e.g., smoking cessation, weight management, diabetes control) –Fluid restriction –Exercise therapy Medical therapy Device therapy Surgical therapy

Treatment (Varies Based on Type of HF) Angiotensin I converting enzyme inhibitors (ACE-I inhibitors) or other cardiac afterload-reducing agents such as angiotensin II receptor blockers, hydralazine, or long-acting nitrates β-adrenergic receptor blocking agents Possibly digoxin or an aldosterone antagonist Diuretic therapy commonly used for fluid overload Antiplatelet and anticoagulation therapies, as indicated Implantable cardiac defibrillator and/or cardiac resynchronization therapy (for patients with NYHA class II to IV HF and QRS duration >120 ms) Left ventricular assist device or cardiac transplant

Exercise Prescription ECG-monitored exercise can be considered. After demonstrating they can tolerate supervised training three times a week, patients can begin a home-based exercise program. (continued)

Exercise Prescription (continued) Special considerations: –Criteria for exercise training in HF patients: NYHA class II or III Stable on standard drug therapy for at least 6 wk Absence of any other cardiac or noncardiac problems that would limit participation in exercise –In addition to common reasons that challenge compliance and attendance (caregiver duties, transportation, and so on), expect additional HF- specific challenges due to medical issues (e.g., frequent hospitalizations, arrhythmias) (continued)

Exercise Prescription (continued) Muscular strength, endurance, and flexibility Cardiorespiratory training –Select activities that engage large muscle groups such as stationary cycling or walking –Frequency: four or five times per week –Intensity: 50% to 80% (safe exertion beyond this point has not been thoroughly investigated) –Duration: 30 to 60 min, varies by individual (continued)

Exercise Prescription (continued) Aerobic: –Intensity: 60% to 80% of heart rate reserve –Frequency: four or five times per week –Duration: 40 min or more per session Resistance: –Intensity: 40% of 1RM upper body, 50% of 1RM lower body –Frequency: one or two times per week –Duration: one set of 12 to 15 reps for each muscle group

Heart Failure Medications and Exercise See table 14.4, “Types of Medications Commonly Used to Treat Heart Failure, Primary Clinical Effects, and Effects on the Exercise Response.”

Conclusion HF is today’s fastest-growing cardiac-related diagnosis. Current research establishes that among eligible patients with stable HF, regular exercise training improves exercise tolerance and quality of life, as well as moderately reducing the risk for all-cause death or hospitalization and cardiovascular death or HF hospitalization. Health care practitioners should include regular exercise training when developing their treatment strategies.