L11 Cardiac Haemodynamics and Heart Failure Flashcards
What is preload?
The stretch on the cardiomyocytes before ventricular ejection. It is the left ventricular end diastolic volume.
What is afterload?
The pressure against which the heart is contracting into. There is an increased after load in hypertension. Afterload is proportional to the average arterial pressure. As aortic and pulmonary pressures increase, the afterload increases on the left and right ventricles respectively.
How does the juxtaglomerular apparatus detect pressure?
The juxtaglomerular apparatus detects increase perfusion at the glomerulus. Sodium concentration is detected in fluid surrounding the distal convoluted tubule. If either is reduce, renin is released. Inactive prorenin is converted to renin and active prorenin.
What is diastolic dysfunction?
HFPEF - Heart Failure with Preserved Ejection Fraction. The heart is nor relaxing between beats and so there is a reversal of the passive and active filling of the ventricles. The ventricle is stiffened and does not fill properly. Right atrial hypertrophy occurs due to increased contraction. There is no cure. HFPEF usually leads to HFREF.
What is systolic dysfunction?
HFREF - Heart Failure with Reduced Ejection Fraction.
The left ventricle is thickened and does not contract properly. There is treatment for HFREF>
What are the cardinal symptoms of heart failure?
- Oedema
- Breathlessness when laying down (orthopnoea)
- Breathlessness when exercise
Other symptoms include:
- Paroxysmal nocturnal dyspnoea
- fatigue
- Ascites and the visceral cavity
What are symptoms of right heart failure?
- Oedema
- Back pressure transmits to the vena cava.
- Internal jugular pressure rises
- Gravity and raised orthostatic pressure causes oedema
- Hepatomegaly and ascites
What are symptoms of left heart failure?
- Pulmonary hypertension
- Pulmonary oedema
- Breathlessness and Low oxygen saturations
- Orthopnoea as blood pools more when laying down
What are causes of heart failure?
- Atherosclerosis
- Atrial fibrillation
- Alcohol (ETOH)
- Hypertension
- Viruses or another cause of myocardial inflammation
- MI
- Genetic factors
What happens when ejection fraction reduces?
- Reduced renal perfusion
- Reduced cardiac output
- Reduced arterial stretch
Reduced systolic blood pressure
What is cardiovascular maladaption?
The body however cannot tell between blood loss and heart failure. This leads to an increased preload and so increased cardiac output. It also leads to an increase in sympathetic activity and a decrease in parasympathetic activity. This works for while as compensation. However too much can lead to failure. If the heart rate goes too fast, you go over the top of the Bowditch curve and can also tilt over into the descending limb of the Starling curve. The individuals cannot cope properly with the increased load that was produced due to compensation. Greater input can then cause the system to move over onto the descending limb of the Frank-Starling curve.
What is adverse remodelling?
To increase load, we get left ventricular hypertrophy to increase the cavity size. If an area in the heart infarcts, it leads to thinning and stretching leading to an aneurysmal left ventricle. The scar is thinner due to the tension of increased stress. Since it is dead, it cannot get thickened. The left ventricular cavity size increases, making people worse.
How do we assess patients for heart failure?
Use an ECHO to work out preload and ejection fraction. It can also be used to look for evidence of hypokinesis/akinesis.
What is used in the acute therapy of heart failure?
- Oxygen to help with breathing (can force in severe patients air into the lungs with severe pulmonary oedema to force fluid out of the lungs).
- Morphine will help with breathing, strain and reduce the preload and take strain of the LV.
- Diuretics (Furosemide and Zaroxyln - strong and used in an acute settiong).
What drug can be symptomatic benefit?
Diuretics
