Women:

250-300g:

Men:

30-350g

What is the preferred energy source for the heart?

Fatty Acids preferably long chain

Glucose and Lactate are also used

Normal - 60-100

Less than 50 bpm suggests dysfunction...note may worsen with cardioactive drugs such as Digoxin (an amino glycoside)

What is the formula for Cardiac Output?

What describes the amount of blood in the ventricle after the AV valves close -- ie. it determines the contractility based on the Frank Starling effect?

What is the name of the force the heart must overcome to pump blood out of the heart and against during systole?

CO=HRxSV

heart rate x stroke volume

Preload

Afterload

Peripheral vascular resistance (PVR)

Chamber Morphology, tension: Radius, wall thickness, stiffness

What is the name and formula for the equation that caluculates Wall Tension?

Laplace's Law

Wall Tension = Pressure x Radius/(2 x wall thickness)

Stroke volume is determined by the contractility of the heart...Frank Starling, wall thickness/flexibility, health of the tissue.

What is the calculation to determine ejection fraction?

Normal/abnormal values?

Ejection Fraction = Stroke Volume/End Diastolic Volume

Normal: 55-85%

Moderate Dysfunction: 30-50%

Severe Dysfunction: <30% (this level is debilitating. Could barely move around.)

Reasons for Cardiac Dysfunction include:

endocarditis,

MI

Valvular Disease

Stiff heart from amyloid deposits (TTR)

What are five principle mechanisms of Cardiovascular Dysfunction?

Pump Failure (i.e. Left ventricular failure, but both sides can fail together or separately)

Obstruction to flow (ex. HTN)

Regurgitant flow (valvular disease...like stenosis, prolapse)

Disorders of cardiac conduction (arrhythmias)

Interruption of circulation

____________: Pathophysiologic state. Heart cannot deliver enough blood to meet the needs of the body.

____________: Clinical syndrome that reflects inadequate pump function.

_________: Systemic hypoperfusion often related to sudden loss of cardiac function.

Heart Failure

Congestive Heart Failure

Shock

Frank-Starling: increased preload yields greater contractility....to a point

Myocardial structural changes...increased muscle mass to push against an increased afterload

Neurohumoral systems: norepi/epi, renin-angiotensin syst., ANP

Diminished Cardiac output is an example of ________ failure.

Accumulation of blood in the venous system is an example of ___________ failure.

Forward failure

Backward Failure

General theme is that the damage caused by some failure of the system works its way backward.

i.e. heart can't pump blood is a foward failure that soon manifests itself backwards as pulmonary edema and then right ventricular congestion...then portal hypertension...etc

What are the most common causes of Left Heart Failure?

(4)

Ischemic Heart Disease (IHD)

HTN (increased afterload)

Aortic/Mitral Disease

Non-ischemic myocardial disease (i.e. Amyloid, viral endocarditis)

In general leads to a progressive damming of blood in the lungs and diminished periph. blood flow.

First the ventricle hypertrophies to adapt to an increase work load (in the case of chronic hypertension, for example).

Then the muscle fails at keeping up with demand

Following failure comes dilation of the ventricular cavity. (During failure atrium is also taking on more of a work load and compensating by enlarging as well.)

This process can be exacerbated by the expansion of the AV valve in the process, which leads to valve incompetence and regurgitating flow back into the system.

What findings in a lung are indications of heart failure?

Both cellular and imaging

Congestion and pulmonary edema

Siderphages -- with pulmonary congestion, blood extravasates into the alveolar spaces. Macrophages move in and phagocytose the blood, leading to intracellular deposits of hemosiderin.

"heart Failure Cells"

Kerley's B Lines (From Wikipedia:

These are short parallel lines at the lung periphery. These lines represent interlobular septa, which are usually less than 1 cm in length and parallel to one another at right angles to the pleura. They are located peripherally in contact with the pleura, but are generally absent along fissural surfaces. They may be seen in any zone but are most frequently observed at the lung bases at the costophrenic angles on the PA radiograph, and in the substernal region on lateral radiographs. Kerley B lines are seen in Congestive Heart Failure (CHF) and Interstitial Lung Diseases (ILD).)

Also seen is orthopnea (SOB), paroxysmal nocturnal dyspnea

Usually, it is secondary to left heart failure (part of the backward damage)

If it is a direct right heart failure, it is usually associated with severe chronic pulmonary hypertension (cor Pulmonale), but other lung diseased may be the cause -- COPD, diffuse lung disease, pulmonary embolism, etc. In these cases there would be limited pulmonary congestion

How would right heart failure manifest itself?

Blood would back up into the vena cava, especially the Portal system (liver, spleen, umbilical area, intestines [superior and inferior mesenterics])

Congestive hepatomegaly (passive). Leads to congestion of hepatic centrilobular veins, causing nutmeg liver. (note, if the failure is left sided, you might see centrilobular necrosis.) Eventual damage leading to fibrosis is "Cardiac Cirrhosis"

Plerual and pericardial effusions

Peripheral edema

renal congestion (>than left heart failure)

Brain Hypoxia