Congestive Heart Failure

Background

Heart Failure (HF) or Congestive Heart Failure (CHF) is a condition in which an abnormal structure or function of the heart impairs its ability to pump enough blood to the rest of the body. HF affects more than 5 million Americans and accounts for approximately 10% of all hospitalizations in the United States. Measurements of stroke index (SI), thoracic fluid index (TFI), and systemic vascular resistance index (SVRI) have been shown to guide diagnosis and therapeutic interventions for HF, as well as predict a patient’s risk of a heart failure event (hospitalization or death).

Application

HF and specifically CHF, occurs commonly when cardiac output is low, as a result of high preload, afterload, and low contractility. SI and TFC can be quantified into four cardiocirculatory quadrants to be used to identify the relative risk of a heart failure event.1 Patients with a high TFI and low SI in the ‘High Risk” Subset have a 7-fold increase in risk of a HF event in the next 14 days than those in the ‘Low Risk’ Quadrant.1

The following adapted algorithm suggests drawing conclusions and establishing a risk prognosis for each patient, based on changes in visit-to-visit SI, SVRI, and TFI.2 Based on the predicted short term risk, specific therapies are suggested to treat the patient.

Publication Conclusions
1 Packer M, et al. Utility of Impedance Cardiography for the Identification of Short-Term Risk of Clinical Decompensation in Stable Patients with Chronic Heart Failure (The PREDICT Trial. J AM Coll Cardiol. 2006; 47:2245-2252 - When a noninvasive hemodynamic test is preformed at regular intervals in patients with HF with a recent event of decompensation, the assessment can identify those patients with a short-term risk of an adverse HF event.1
- High risk for HF event within 14 days for patients with low SI and high TFI1
2 Strobeck H, Silver M. Beyond the Four Quadrants: The Critical and Emerging Role of Impedance Cardiography in Heart Failure. Congest Heart Fail. 2004;10(suppl 2):1-6 - Assessment of risk may lead to an increased clinical surveillance or a decision to intervene in treatment to prevent a negative patient outcome.2
- Noninvasive hemodynamics may also aid is the assessment of a stable and low risk hemodynamic patient profile, toward the initiation and uptitration of specific pharmacological agents.2
3 Yancy C and Abraham WT. Noninvasive Hemodynamic Monitoring in Heart Failure: Utilization of Impedance Cardiography. CHF. 2003;9:241-250 - “Hemodynamic evaluation is helpful for optimization of treatment, monitoring clinical outcomes, and overall prognostication of heart failure patients…[and is an] economical outpatient procedure which has been shown to provide reliable hemodynamic values compared to those obtained from pulmonary artery catheterization”.3
4 Castellanos LR et al. B-Type Natiuretic Peptide and Impedance Cardiography Testing at the Time of Routine Echocardiography Predict Subsequent Heart Failure Events. J Card Fail. 2005;11(6):S123 - B-Type Natiuretic Peptide and Systolic Time Ratio (obtained from noninvasive test) are the strongest predictors of HF events, regardless of the presence or absence of left ventricular dysfunction.4
- Additionally, a combination of STR and BNP result in stronger predictions of a HF event than either parameter alone.4