Chapter 22 - Guyton Flashcards

1
Q

Define heart failure.

A

failure of the heart to pump enough blood to satisfy the needs of the body

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2
Q

What two main effects occur immediately as a result of myocardial infarction?

A

reduced cardiac output and damming of blood in the veins resulting in increased venous pressure

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3
Q

What occurs after acute cardiac failure to compensate for reduced cardiac output?

A

strong sympathetic stimulation with parasympathetic inhibition (heart becomes stronger pump and mean systemic filling pressure increases–>increased venous return)

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4
Q

How long does it take for the sympathetic reflex to kick in after a myocardial infarction?

A

The sympathetic reflexes become maximally developed in about 30 seconds.

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5
Q

After the first few minutes of an acute heart attack, a prolonged semi-chronic state begins, characterized mainly by two events:

A

retention of fluid by the kidneys and (2) varying degrees of recovery of the heart itself over a period of weeks to months

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6
Q

In what two ways can fluid retention be helpful in a patient with cardiac failure?

A

it increases the mean systemic filling pressure, which increases the pressure gradient for causing venous flow of blood toward the heart; second, it distends the veins, which reduces the venous resistance and allows even more ease of flow of blood to the heart

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7
Q

What are some of the detrimental effects of excessive fluid retention in severe cardiac failure?

A

overstretching of the heart, thus weakening the heart still more; filtration of fluid into the lungs, causing pulmonary edema and consequent deoxygenation of the blood; and development of extensive edema in most parts of the body

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8
Q

What is compensated heart failure?

A

chronic compensations resulting from partial heart recovery and renal retention of fluid (several days to several weeks later)

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9
Q

Many people, especially older people, have ______ resting cardiac outputs but mildly to moderately ________ right atrial pressures because of various degrees of “compensated heart failure.”

A

normal; elevated (increase in right atrial pressure can maintain normal cardiac output despite continued weakness of the heart - these individuals have a diminished cardiac reserve)

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10
Q

The main cause of decompensated heart failure is:

A

failure of the heart to pump sufficient blood to make the kidneys excrete daily the necessary amounts of fluid.

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11
Q

What are some treatment options for decompensated heart failure (otherwise the patient will die from fluid retention)?

A

strengthening the heart in any one of several ways, especially by administration of a cardiotonic drug, (digitalis); administering diuretic drugs to increase kidney excretion while at the same time reducing water and salt intake

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12
Q

What is the mechanism of action for digitalis?

A

strengthen heart contraction by increasing the quantity of calcium ions in muscle fibers (depresses the calcium pump that normally pumps calcium out)

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13
Q

In unilateral left heart failure, why could pulmonary edema result?

A

mean pulmonary filling pressure rises because of shift of large volumes of blood from the systemic circulation into the pulmonary circulation–>pulmonary edema

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14
Q

Why does acute cardiac failure typically NOT result in immediate peripheral edema?

A

severe acute cardiac failure often causes a fall in peripheral capillary pressure rather than a rise

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15
Q

Once a person develops _________ shock, the survival rate is often less than 15 per cent.

A

cardiogenic or cardiac

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16
Q

After the first day or so of overall heart failure or of right-ventricular heart failure, peripheral edema does begin to occur principally because of:

A

fluid retention by the kidneys

17
Q

Three known causes of the reduced renal output of urine during cardiac failure:

A
  1. Decreased glomerular filtration; 2. Activation of the renin-angiotensin system and increased reabsorption of water and salt by the renal tubules; 3. Increased aldosterone secretion
18
Q

Excess ____________ is one of the most powerful stimuli known for aldosterone secretion, and the ___________ concentration rises in response to reduced renal function in cardiac failure.

A

potassium

19
Q

______ __________ ______ is a hormone released by the atrial walls of the heart when they become stretched.

A

Atrial natriuretic factor (ANF) - this prevents extreme congestive symptoms during cardiac failure by increasing excretion of salt and water at the kidneys

20
Q

What are some treatment options for acute pulmonary edema occurring in a patient with late-stage heart failure (act quick or pt. is dead within 20 min - 1 hour)?

A

putting tourniquets on both arms and legs to sequester much of the blood in the veins; bleeding the patient; giving a rapidly acting diuretic, such as
furosemide; giving the patient pure oxygen to breathe (reverse the blood oxygen desaturation); giving the patient a rapidly acting cardiotonic drug, such as digitalis, to strengthen the heart

21
Q

The maximum percentage that the cardiac output can increase above normal is called the _______ _______.

A

cardiac reserve

22
Q

If a person is unable to increase cardiac output (low cardiac reserve), what symptoms will they have as soon as they start to exercise or stress the heart?

A

dyspnea, extreme muscle fatigue, excessive increase in HR

23
Q

The normal state of the circulation is a cardiac output and venous return of __ L/min and a right atrial pressure of __ mm Hg.

A

5; 0

24
Q

During the ensuing week after an acute heart attack, the cardiac output and venous return curves rise further because of:

A

1) some recovery of the heart and 2) renal retention of salt and water, which raises the mean systemic filling pressure

25
Q

Two days after an acute heart attack, a patient has a cardiac output rises to 4.2 L/min and the right atrial pressure to 7 mm Hg. What is the prognosis for this patient?

A

buh-bye, The reason the patient will die is decompensated heart failure has resulted from the fact that the cardiac output curve never rises to the critical level of 5 L/min needed to re-establish normal kidney excretion of fluid that would be required to cause balance between fluid input and output.

26
Q

Two types of high-output cardiac failure?

A

arteriorvenous fistula (excessive venous return but pumping capability of heart not depressed); beriberi (venous return is greatly increased because of diminished systemic vascular resistance, but pumping capability of the heart is depressed)