Disordered Breathing During Exercise in Heart Failure Flashcards
Define Chronic Heart Failure
Congestive Heart Failure (CHF)
- Inability of Heart to supply sufficient blood flow to meet demand of body
How many Classes of Heart Failure does the New York Heart Association Classify?
- Four
How Does New York Heart Association Classify Class I of Heart Failure?
No Limitation
- Ordinary physical exercise does not cause undue fatigue, dyspnoea, or palpitations
Define Class II Heart Failure from the New York Heart Association
Slight Limitation of Physical Activity
- Comfortable at rest
- Ordinary activity results in fatigue, palpitations, or dyspnoea
Define Class III Heart Failure
Marked Limitation of Physical Activity
- Comfortable at Rest
- Less than ordinary activity results in symptoms
Define Class IV Heart Failure
Unable to carry out any physical activity without discomfort
- Symptoms present at rest
- Increased discomfort with any physical activity
What is Stroke Volume?
- Volume of blood pumped per contraction
What is End-Diastolic Volume (EDV)? What is End-Systolic Volume (ESV)?
EDV
- Volume of blood in ventricle before contraction
ESV
- Volume of blood in ventricle after contraction
What is Cardiac Output?
- Total Volume of blood pumped by the ventricle per minute
- Q = HR x SV
What is an Ejection Fraction (EF)?
- Proportion of blood pumped out of the left ventricle each beat
- EF = SV/EDV
- Average 60% at rest
How is Heart Failure Defined Based on Ejection Fraction?
- Normal EF should be 50-70%
- In Systolic Heart Failure, EF drops below 40%
What happens in Restrictive Pulmonary Disease?
Forced Expiratory Volume
- Reduced
Forced Vital Capacity
- Reduced
FEV1.0/FVC%
- Normal or even increased
What happens during a Obstructive Pulmonary Disease?
Forced Expiratory Volume
- Reduced significantly
Forced Vital Capacity
- Reduced Slightly
FEV1.0/FVC%
- very low ratio
What are the Symptoms of Heart Failure?
- Poor ventricular systolic function
- Poor Hemodynamic Performance
- Weak respiratory Muscles
- Increased Left Atrial and Pulmonary Pressure
- Lung Fluid Balance changed
- Neuro-humoral Activity
Is Heart Failure obstructive or Restrictive?
- Both
What is the disordered Breathing Pattern with Exercise?
- Rapid Shallow Breathing (tachypnea)
- Oscillatory Breathing
- Reduced End-expiratory lung volume at rest
- Significant expiratory flow limitation and adequate inspiratory reserve volume
What are the different patterns of Oscillatory Ventilation?
- Noisy oscillations at early exercise (considered no-exercise oscillatory breathing
- Initial to intermediate phases of exercise: disappears around 60% whole exercise
- Entire Exercise Oscillation: Wide amplitude of cycles that persist
Where does Ventricular Hypertrophy occur in Heart Failure?
- Left Ventricle
- Right Ventricle
- Left Atrial Enlargement
What is Cardiomegaly?
- Enlargement of the Heart due to Heart Failure
What was the Rationale for the Study “Influence of cardiomegaly on disordered breathing during exercise in chronic heart failure”?
- Hypothesize that significant changes in the cardiac system could have profound effects on the pulmonary system, particularly during physical activity
- Determine the relationship between cardiac size and breathing patterns during exercise
What was the Hypothesis of The Study on Cardiomegaly?
- Increased competition for intra-thoracic space caused by the increased cardiac volume associated with HF contributes to the tachypnoeic breathing pattern during exercise
What was the inclusion / exclusion criteria for the study on cardiomegaly?
- Patient with a history of ischaemic or dilated cardiomyopathy
- Stable HF symptoms (>3months)
- Duration of HF Symptoms (>1year)
- Left ventricular ejection fraction of <35%
- Body mass <35kg/m^2
- Current Non-smoker (past 15 year)
- Smoking history less than 10 pack-years
What was the Control Group for the study on Cardiomegaly?
- Similar age, gender, and height distribution to the HF group
- Normal Cardiac Function (EF >50%)
- No history of hypertension
- No history of lung disease
- No history of coronary artery disease
What were the Protocols used for the study on cardiomegaly?
- Graded Exercise Testing
- Spirometry
- Chest Radiograph (PA and LAT)
- Cardiomegaly: cardiac volume as a percent of total thoracic cavity volume (TTCV)
How were the groups determined for the study on Cardiomegaly?
HF group median heart size
- 12% Total Thoracic Cavity Volume
Group A
- CV < Median
Group B
- CV > Median
Control
- Normal Cardiac Volume
- No HF
What were the different measurements used in the Study on Cardiomegaly?
Spirometry
- Forced Vital Capacity (FVC)
- Forced Expiratory Volume in one Second (FEV1)
- Mean FEF between 25-75% (FEF25-75)
Diffusing capacity of the lung for carbon monoxide (DLco)
Alveolar Volume using single breath method
What were the methods used to test exercise in the study on cardiomegaly?
- Symptom-limited incremental treadmill test
- Rating of perceived exertion (Borg)
- VO2
- VCO2
- VE
- VT
- RR
- Partial pressure end-tidal oxygen and carbon dioxide
What were the Results of the Study on Cardiomegaly at 75% peak exercise?
- Control had higher VO2, VCO2, VE
- Group A/B had higher VE/VCO2 compared to control
- Group A reduced VE due to lower RR
- Group B reduced VE due to reduced VT
What was the implications of the results from the study on cardiomegaly?
- Cardiac Size is independently associated with VT at 75% of VO2 peak (-58ml/min per +10% cardiac size)
- At VO2 peak VT was statistically significant (-315ml/min per +10% cardiac size)
- Cardiac size was significantly related to reduced VT in the HF patients
What was the Relationship between VT% of TTCV volume and VE% of TTCV volume?
- HF patients with larger cardiac sizes demonstrated significant levelling off of VT
Why is there a change in respiratory rate and tidal volume in HF patients with cardiomegaly?
- Larger cardiac volume changes breathing architecture during exercise
- Contributes to symptoms of dyspnoea and fatigue
What is the relationship between cardiac volume and total lung volume?
- Reduced lung volume reduces the effectiveness of the elastic recoil component of exhalation
- Reduced stretch of lung results in reduced maximal volume and expiratory flow
- HF patient with largest cardiac volume have reduced FVC and FEV 1.0
