week of 1/7 Flashcards
Valvular Heart disease HTN, blood flow regulation, HF Tx
Which of the following describes a mechanism that regulates blood pressure that can contribute to hypertension?
A) Increased bradykinin
B) Increased firing of afferent baroreceptors (in the carotid sinus and aortic arch, etc.)
C) Decreased intracellular calcium levels
D) Increased aldosterone
The correct answer is D). Aldosterone, which is secreted by the adrenal gland, leads to increased sodium absorption which leads to an increase in intravascular volume that leads to higher blood pressure. Increased aldosterone can happen through stimulation by the renin-angiotensin system (increased angiotensin II). Primary aldosteronism can also be caused by an adrenal adenoma or from bilateral hyperplasia of the adrenal glands.
A is not correct. Bradykinin is a vasodilator, so increased bradykinin will lead to vasodilation and a decrease in peripheral vascular resistance and a lower blood pressure. This can be seen in Pouiselle’s Law, where increasing the vessel radius leads to a decrease in blood pressure. Decreases in Angiotensin II levels can lead to increased bradykinin levels.
B is not correct. The afferent baroreceptors in the carotid sinus, aortic arch, left ventricle, and juxtaglomerular apparatus in the kidney senses effective arterial blood volume and fires when high blood pressures are detected. Increased firing of afferent baroreceptors leads to decreased sympathetic tone which leads to decreased blood pressures through decrease in cardiac contractility, heart rate, and arterial constriction.
C is not correct. Increased, not decreased, intracellular calcium levels in the vascular endothelium leads to vasoconstriction which increases peripheral vascular resistance and increases blood pressure. Calcium channel blockers that decrease intracellular calcium levels thus are used to treat hypertension.
Learning issue covered: 4. Explain the mechanisms responsible for the pathogenesis of hypertension (MKS1b)
SM 141 a: Hypertension I
A 53 year old patient is here for a follow-up visit. Her blood pressure is 146/100 mmHg, and she had a similar blood pressure at her last visit. She has a history of diabetes and chronic kidney disease. Which of the following pharmacologic agents should be chosen for initial treatment?
A) Amlodipine
B) Lisinopril
C) Hydrochlorothiazide
D) Labetalol
The answer is B) Lisinopril, an ACE inhibitor. ACE inhibitors and Angiotensin II receptor blockers are recommended as first line treatments for patients with diabetes and chronic kidney disease. ACE-inhibitors and ARBs have been shown to slow the progression of kidney disease in patients with diabetic nephropathy.
A is incorrect. Amlodipine is a calcium-channel blocker. CCBs are safe in patients with diabetes, renal insufficiency, hyperlipidemia, and asthma, but are not the first-line treatment for patients with diabetes and chronic kidney disease. It can be used as a good adjunct in combination drug therapy. CCBs should be avoided or selected carefully in patients with heart failure or arrhythmias.
C is incorrect. Hydrochlorothiazide is a thiazide diuretic. Thiazides are the most commonly used diuretic and often is the first line antihypertensive used in patients. However, thiazides work the best in patients with normal renal function, and can cause metabolic side effects such as elevation of serum glucose, cholesterol and triglyceride levels. Thus they are not the first-line treatment in patients with diabetes or chronic kidney disease.
D is incorrect. Labetalol is a beta-blocker. Beta-blockers can also be used to slow the heart rate in patients with atrial fibrillation or supraventricular arrhythmias. However beta-blockers can cause hyperglycemia and increases in triglyceride levels, and are thus not first-line treatments in patients with diabetes and chronic kidney disease.
Learning Issue covered: SM 34: Apply knowledge of pharmacologic strategies to treat hypertension to case-based scenarios and identify reasons to choose one agent over another in specific patient populations.
SM 144a: Hypertension II
In which of the following organs is autoregulation not primarily determined by the production of local metabolites?
- Brain
- Heart
- Skeletal muscle
- Skin
The correct answer is D. Autoregulation of vascular beds in the skin is predominantly controlled by sympathetic stimulation, not by local metabolites. These cutaneous sympathetic nerves are regulated by temperature. For example, increased temperature leads to vasodilation to allow for dissipation of heat.
A is incorrect. Autoregulation in the brain is determined by local metabolites that are vasodilatory including CO2 which is affected by the blood pH. Autoregulation in the brain is also influenced by tissue pressure since there is limited compliance in the brain interstitium.
B is incorrect. Autoregulation in the heart is determined by local metabolites that are vasodilatory including adenosine from ATP metabolism, nitric oxide, carbon dioxide, and decreased oxygen levels.
C is incorrect. Autoregulation in the skeletal muscle is determined by local metabolites that are produced during exercise including lactate, adenosine, potassium, hydrogen ions, and carbon dioxide. This is also an example of active hyperemia.
Learning issues covered: 1. Define autoregulation of blood flow and define which vascular beds exhibit this.
SM142a) Local Blood flow regulation
A 58 year old Hispanic woman presents with fatigue and shortness of breath after 15 minutes of walking that has developed over the past year. She sleeps with two pillows at night and reports that she “sometimes wakes up at night out of breath.” She has a history of uncontrolled hypertension. On physical exam there is 3+ pitting edema bilaterally, her heart rate is 110 bpm with a respiratory rate of 22. An elevated JVP is observed. On echocardiography the left ventricular ejection fraction is measured to be 37%. Which of the following is the best first-line treatment option?
A) Implantable cardioverter defibrillator
B) Digoxin and an ARB
C) An ACE-inhibitor, a beta-blocker, and a diuretic
D) Ivabradine
E) Hydralazine and nitrates
The correct answer is C. This patient has heart failure with a reduced ejection fraction (HFrEF), since her ejection fraction is < 40%, most likely caused by chronic uncontrolled hypertension. Common symptoms of HFrEF seen in this patient are dyspnea on exertion caused by pulmonary edema and decreased cardiac output, and orthopnea and paroxysmal nocturnal dyspnea because of increased venous return when lying down. Common signs of heart failure seen in this patient include an elevated JVP caused by increased right atrial pressure and peripheral edema from fluid transudation.
The first-line treatment for HFrEF is an ACE-Inhibitor or ARB and a beta blocker with a diuretic added as needed. Since the patient has fluid overload evidenced by elevated JVP and peripheral edema, a diuretic can be added.
A is incorrect. An implantable cardioverter defibrillator should be considered if the left ventricular ejection fraction is less than or equal to 35%.
B is incorrect. Digoxin and an ARB would not be considered first-line treatment. Digoxin can be considered in patients with atrial fibrillation or as an add-on if there are persisting signs and symptoms of heart failure on follow-up.
D is incorrect. Ivabradine targets the If current in the sinoatrial node to reduce the heart rate. It is a treatment option if the patient has a HR greater than 70 bpm in sinus rhythm, and is already taking the highest dose of a beta blocker. It is thus not a first-line treatment and a beta-blocker should be given first.
E is incorrect. Hydralazine and nitrates should be considered if signs and symptoms persist in African-American patients, where it has shown to improve both symptoms and mortality.
Learning Issue covered: SM 26: Define the clinical syndrome of heart failure, relate this syndrome in its various manifestations to underlying hemodynamic changes, and describe the differences between: left-sided and right-sided heart failure; high-output and low-output heart failure; heart failure with preserved ejection fraction (HFpEF) and heart failure with reduced ejection fraction (HFrEF). [MKS-1b]
SM 27: Explain pharmacologic therapy of HFrEF. [MKS-1e]
SM 143a: Heart Failure Treatment
Which of the following correctly describes blood flow during fetal circulation?
A) IVC to the heart through the foramen ovale to the pulmonary artery to the patent ductus arteriosus and descending aorta
B) Umbilical vein to portal vein to the IVC to the ductus venosus
C) Umbilical vein to ductus venosus to IVC to the heart through the foramen ovale to the aorta
D) Deoxygenated blood goes to the right ventricle to the pulmonary artery to the ductus arteriosus to the descending aorta to the umbilical vein to the placenta
The correct answer is C. During fetal blood circulation there are 3 important shunts. Also, of note the umbilical vein is oxygenated with 80% O2 saturation while the umbilical arteries have low O2 saturation.
The three important shunts are 1) blood enters the fetus through the umbilical vein into the ductus venosus into the IVC. This bypasses hepatic circulation and the portal vein 2) highly oxygenated blood reaching the heart goes through the foramen ovale and into the aorta to supply the body and brain 3)deoxygenated blood enters the heart through the SVC, enters the right ventricle into the main pulmonary artery and is shunted to the descending aorta through the patent ductus arteriosus. This is due to high pulmonary artery resistance.
A is incorrect. Oxygenated blood goes through the foramen ovale in the right atrium into the left atrium and aorta, not to the pulmonary artery.
B is incorrect. The umbilical vein does not go to the portal vein, instead it is shunted through the ductus venosus into the IVC.
D is incorrect. Deoxygenated blood from the descending aorta goes to the umbilical arteries not the umbilical vein back to the placenta.
Learning Issue covered: 5. Describe the unique anatomic features of the vasculature that provide for each regional circulations
SM 145a: Peripheral vascular blood flow regulation
Which of the following occurs if a patient is given a low dose of epinephrine?
- Increase in heart rate and contractility
- Increase in total peripheral resistance
- Decrease in arterial blood pressure
- Vascular effects of alpha receptors dominate
The correct answer is A. Epinephrine binds to both beta and alpha receptors with a greater effect on beta receptors. Its effects on beta1 receptors will lead to an increased heart rate and contractility, which leads to greater cardiac output and an increase in arterial blood pressure.
B is incorrect. When given a low dose of epinephrine, beta2-receptor effects dominate over alpha1 receptor effects. So vasodilation dominates leading to a net effect of a decrease in total peripheral resistance, not an increase.
C is incorrect. Epinephrine increases the arterial blood pressure by increasing cardiac output.
D is incorrect. At a low dose, vascular effects of the beta receptors dominate. At a high dose, the alpha effects predominate.
Learning issues covered: 4. Describe the roles of oxygen, vasoactive tissue metabolites, physical factors and others in the regulation of tissue blood flow.
SM146a: Regulation of Arterial pressure
A 23 year-old woman presents to the emergency department with trauma to her leg and blood loss. When she is supine, her blood pressure is 88/60 mmHg and her heart rate is 98 bpm. When she is upright, her heart rate further increases to 115 bpm. Which of the following explains her further increase in heart rate?
- Increased afferent baroreceptor firing
- Decreased venous return
- Decreased efferent sympathetic firing
- Increased afterload
The correct answer is B. The patient is hemorrhaging and thus has decreased venous return to the heart. This leads to decreased arterial pressure, decreased stretch of the blood vessel , decreased afferent baroreceptor firing, increased efferent sympathetic firing and decreased efferent parasympathetic stimulation, resulting in vasoconstriction through alpha 1 receptors, an increase in heart rate through beta 1 receptors, and an increase in blood pressure.
When the patient stands up, venous return is further decreased due to blood pooling in her legs leading to a further decrease in blood pressure. Through the same baroreceptor mechanism, the heart rate thus further increases.
Thus, the physiological response to standing upright from a supine position is similar to the response to mild hemorrhage or loss of intravascular volume (severe diarrhea, etc.).
A is incorrect. The decreased arterial pressure would lead to decreased afferent baroreceptor firing, not increased.
C is incorrect. Increased efferent sympathetic firing, not decreased sympathetic firing leads to increased systemic vascular resistance and increased heart rate through alpha1 and beta 1 receptors.
D is incorrect. Hemorrhage would lead to decreased afterload (decreased mean arterial pressure), not increased.
Learning issue covered: 2. Explain the arterial baroreceptor reflex. 5. Explain the circulatory adjustments that occur as a result of normal activities of the body (standing, changing position, etc.).
