6 cardiology high yield

CA01.1- To understand the following topics and how they may be tested on USMLE Step 1 Cardiovascular System Course Objectives: 2... CA01.1- – Beta and alpha adrenergic receptors and

CA01.1-

To understand the following topics and how they may be

tested on USMLE Step 1

Cardiovascular System Course Objectives:

2

CA01.1-

– Beta and alpha adrenergic receptors and

their role in the cardiovascular system

– Cardiac output

– Resistance, pressure, and flow

– Cardiac function curve

Learning Objectives

3

CA01.2-

Kaplan Pharmacology 2011 : Table II-3-2

FA 2012: 263.1 • FA 2011: 236 • FA 2010: 232 • ME 3e: 169 1

CA01.3-

KNOW THE FICK PRINCIPLE

CO = O 2 Consumption / (Arterial O 2 – Venous O 2 )

• O 2 Consumpsion  often given

• Arterial O2 = [Hgb] x [1.34] x [Arterial O2 Saturation]

• Venous O2 = [Hgb] x [1.34] x [Venous O2 Saturation]

FA 2012: 280.2 • FA 2011: 254.2 • FA 2010: 250 •

CA01.3-

Mean Arterial Pressure (MAP)…

MAP = (CO) X (TPR)

MAP = ( 2 / 3 Diastolic Pressure ) + ( 1 / 3 Systolic Pressure )

When heart rate increases, so does the cardiac output and the mean arterial pressure, all things being equal

FA 2012: 280.2 • FA 2011: 254.2 • FA 2010: 250 •

CA01.4-

Kaplan Physiology 2011 : Figure IV-1-9

FA 2012: 281.1 • FA 2011: 255.1 • FA 2010: 251 •

CA01.4-

PRELOAD = Left Ventricular EDV

FA 2012: 281.2 • FA 2011: 255.2 • FA 2010: 251 •

CA01.4-

AFTERLOAD = Mean Arterial Pressure (MAP)

FA 2012: 281.2 • FA 2011: 255.2 • FA 2010: 251 •

CA01.4-

Kaplan Physiology 2011 : Figure VI-1-1

FA 2012: 281.2 • FA 2011: 255.2 • FA 2010: 251 •

CA01.4-

Bitzblitz, commons.wikimedia.org, Used With Permission

Frank-Starling Curve

Increased Contractility

Decreased Contractility

CA01.4-

NEED TO KNOW !

EF tells us about the heart’s contractility

EF = SV / EDV = (EDV-ESV) / EDV

A decrease in EF is seen in heart failure

Echocardiograms are often used to diagnose

heart failure by measuring ejection fraction!

FA 2012: 282.1 • FA 2011: 255.4 • FA 2010: 251 •

CA01.5-

Resistance (R) = 8(viscosity) x Length

π r 4

As viscosity increases, resistance increases

Examples: Polycythemia, multiple myeloma

As radius (r) increases, resistance decreases

The aorta has less resistance to flow than a capillary

FA 2012: 282.2 • FA 2011: 256.1 • FA 2010: 252 •

CA01.5-

FA 2012: 282.2 • FA 2011: 256.1 • FA 2010: 252 •

3

CA01.5-

Kaplan Physiology 2011 : Figure V-1-4

FA 2012: 282.2 • FA 2011: 256.1 • FA 2010: 252 •

CA01.5-

Cardiac and Vascular Function Curves

commons.wikimedia.org Used with permission

FA 2012: 282.3 • FA 2011: 256.2 • FA 2010: 252 •

ME 3e: 243

filling pressure

5

CA02.1-

Kaplan Physiology 2011 : Figure VI -1-6

FA 2012: 283.1 • FA 2011: 257.1 • FA 2010: 253 •

CA02.1-

FA 2012: 283.1 • FA 2011: 257.1 • FA 2010: 253 •

CA02.1-

Kaplan Physiology 2011 : Figure VI -1-6

FA 2012: 283.1 • FA 2011: 257.1 • FA 2010: 253 •

CA02.1-

Bitzblitz, commons.wikimedia.org, Used With Permission

Increased Contractility

Decreased Contractility

CA02.1-

• Points:

– Phase 4 longer – Larger EDV – Wider curve – Increased PVL area – Increased SV and CO

FA 2012: 283.1 • FA 2011: 257.1 • FA 2010: 253 •

CA02.1-

FA 2012: 283.1 • FA 2011: 257.1 • FA 2010: 253 •

CA02.1-

Kaplan Physiology 2011 : Figure VI -1-6

FA 2012: 283.1 • FA 2011: 257.1 • FA 2010: 253 •

CA02.2-

Kaplan Physiology 2011 : Figure VI -1-1 & Figure VI -1-3

FA 2012: 283.1 • FA 2011: 257.1 • FA 2010: 253 •

CA02.3-

Kaplan Physiology 2011 : Fig V-1-18

FA 2012: n/a • FA 2011: 265.1 • FA 2010: 261 •

CA02.3-

Kaplan Physiology 2011 : Fig X-4-9

FA 2012: n/a • FA 2011: 265.1 • FA 2010: 261 •

CA02.3-

FA 2012: n/a • FA 2011: 265.1 • FA 2010: 261 •

CA02.3-

Return to this chart later for review…

FA 2012: 290.3 • FA 2011: 265.2 • FA 2010: 261 •

CA02.3-

Kaplan Pathology 2011 : Fig 5-5

FA 2012: 290.3 • FA 2011: 265.2 • FA 2010: 261 •

CA02.3-

Return to this chart later for review…

FA 2012: 290.3 • FA 2011: 265.2 • FA 2010: 261 •

CA02.3-

Kaplan Physiology 2011 : Fig VII-3-8

FA 2012: 290.3 • FA 2011: 265.2 • FA 2010: 261 •

CA02.3-

Don’t get tricked with Cushing’s Triad…

ICP Via sympathetic NS Hypertension Via sympathetic NS

Inappropriate response

Appropriate response

Bradycardia

TRIAD = Hypertension + Bradycardia + Respiratory Depression

FA 2012: 290.3 • FA 2011: 265.2 • FA 2010: 261 •

CARDIO3.1-

Lecture III

• Autoregulation of blood flow

• Capillary fluid exchange

CARDIO3.1-

Nevit Dilmen, commons.wikimedia.org, Used With Permission

FA 2012: 291.1 • FA 2011: 265.3 • FA 2010: 261 •

CARDIO3.1-

FA 2012: 291.3 • FA 2011: 266.2 • FA 2010: 262 •

ME 3e: 252

Autoregulation

Kaplan Physiology 2011 : Figure V-2-2

What factors control local blood flow?

• Heart: O2, adenosine, NO

• Brain: arterial pCO2/pH

• Kidney: tubuloglomerular feedback

• Lungs: hypoxic vasoconstriction (next slide)

• Skeletal muscle: lactate, adenosine, potassium

3

CARDIO3.1-

FA 2012: 291.4 • FA 2011: 266.3 • FA 2010: 262 •

CARDIO3.2-

DIRECT SYMPATHOMIMETICS

Norepinephrine

Dobutamine Dopamine Epinephrine

FA 2012: n/a • FA 2011: 240 • FA 2010: 236 •

CARDIO3.2-

Kaplan Pharmacology 2011 : Figure II-3-5c

FA 2012: n/a • FA 2011: 240 • FA 2010: 236 •

CARDIO3.2-

Kaplan Pharmacology 2011 : Figure II-3-4

FA 2012: n/a • FA 2011: 240 • FA 2010: 236 •

– Does dependent effect:

– Causes vasoconstriction via action upon α 1 receptors (dose dependent)

– Causes cardiac stimulation via B 1 receptor stimulation

FA 2012: 266.3 -267.1 • FA 2011: 240 • FA 2010: 236 •

ME 3e: 193

Β 1 effects α 1 effects (low doses) (high doses)

4

CARDIO3.2-

Kaplan Pharmacology 2011 : Figure II-3-2

FA 2012: 266.3 • FA 2011: 240 • FA 2010:

236 • ME 3e: 193 5

CARDIO3.2-

FA 2012: 267.1 • FA 2011: 240 • FA 2010:

236 • ME 3e: 194

• Both amphetamines and cocaine

are indirect sympathomimetics

• Both increase endogenous

norepinephrine in the synapse

6

CARDIO3.3-

Clinical Pearls…

Clonidine often used to treat opiate withdrawal

– Dampens the sympathetic response that occurs during opiate withdrawal

α-methyldopa indicated in hypertension in pregnancy

FA 2012: 267.2 • FA 2011: 241.1 • FA 2010: 237 •

CARDIO3.4-

Chikumaya, commons.wikimedia.org, Used With permission

FA 2012: 291.2 • FA 2011: 266.1 • FA 2010: 262 •

CA04.1 -

Kaplan Physiology 2011 : Figure VI -1-6

FA 2012: n/a • FA 2011: 260.1 • FA 2010: 256 •

CA04.1 -

Ventricular Action Potential

Kaplan Physiology 2011 : Figure VI -1-6

FA 2012: 286.1 • FA 2011: 260.2 • FA 2010: 256 •

CA04.1 -

EM of Intercalated Disk with Gap Junction (arrow) Adjacent to an Adhering

Junction with Intracellular Density

Kaplan Physiology 2011 : Figure VI -1-6

FA 2012: n/a • FA 2011: 260.1 • FA 2010: 256 •

CA04.1 -

Mechanism of Action of Voltage-Gated Na+ Channels

FA 2012: 286.1 • FA 2011: 260.2 • FA 2010: 256 •

CA04.2 -

Glenlarson, commons.wikimedia.org, Used With permission

Normal ECG Demonstrating Sinus Rhythm

FA 2012: 288.1 • FA 2011: 262.1 • FA 2010: 258 •

CA04.2 -

EKG Leads

FA 2012: 288.1 • FA 2011: 262.1 • FA 2010: 258 •

CA04.2 -

commons.wikimedia.org Used with permission

FA 2012: 288.1 • FA 2011: 262.1 • FA 2010: 258 •

CA04.2 -

Normal Pattern of an ECG

Kaplan Physiology 2011 : Figure VI -1-6

FA 2012: 288.1 • FA 2011: 262.1 • FA 2010: 258 •

4

•Some impulses are not

transmitted through the AV node

•No impulses are conducted

from the atria to ventricles

6

CA05.3- 1

Cardiac Action Potentials in Fast-Response Fibers

Kaplan Physiology 2011 : Figure VI -1-6

FA 2012: 310.1 • FA 2011: 284.1 • FA 2010: 280 • ME

3e: 237

CA05.3-

Mechanism of Action of Voltage-Gated Na+ Channels

Kaplan Physiology 2011 : Figure VI -1-6

FA 2012: 310.1 • FA 2011: 284.1 • FA 2010: 280 • ME

CA05.3-

Cardiac Action Potentials in Fast-Response Fibers

Kaplan Physiology 2011 : Figure VI -1-6

• Class IA drugs block Na+

channels and increase AP duration

• Examples:

quinidine, procainamide, disopyramide

• Should not be used in patients with a long QT interval

FA 2012: 310.1 • FA 2011: 284.1 • FA 2010: 280 • ME

The toxicity is increased in all class I antiarrhythmics with HYPERkalemia

FA 2012: 310.1 • FA 2011: 284.1 • FA 2010: 280 • ME

CA05.3-

Cardiac Action Potentials in Fast-Response Fibers

Kaplan Physiology 2011 : Figure VI -1-6

• Class IB drugs decrease AP duration; lidocaine, mexiletine,

phenytoin

• Class IC drugs have no effect on

AP duration;

flecanide, encainide, propafenone; pro- arrhythmic

FA 2012: 310.1 • FA 2011: 284.1 • FA 2010: 280 • ME

The toxicity is increased in all class I antiarrhythmics with HYPERkalemia

FA 2012: 310.1 • FA 2011: 284.1 • FA 2010: 280 • ME

CA05.4-

FA 2012: 311.1 • FA 2011: 285.1 • FA 2010: 281 • ME

3e: 269

Hypertension Angina Chronic heart failure (carvedilol, labetalol, metoprolol)

Arrhythmia (propranolol, acebutolol, esmolol) Glaucoma (timolol) Migraine, tremor, thyrotoxicosis (propranolol)

Decreased libido

1

• Exacerbation of asthma with use of non-selective β-blockers

• Can mask signs of hypoglycemia in diabetics

FA 2012: 311.1 • FA 2011: 285.1 • FA 2010: 281 • ME

CARDIO5_5 - 1

Cardiac Action Potentials in Fast-Response Fibers

Kaplan Physiology 2011 : Figure VI -1-6

• Class III drugs block K+

channels; sotalol, amiodarone

FA 2012: 310.1 • FA 2011: 284.1 • FA 2010: 280 • ME

3e: 237

ketoacidosis because they are grossly hypokalemic and

at risk for arrhythmias

and seizures in pre-eclampsia!

1

CARDIO6_2c- 1

Abnormal Splitting of the Second Heart Sound (S2)

FA 2012: 284.1 • FA 2011: 258.1 • FA 2010: 254 • ME

3e: 254

CARDIO6_2c- 2

COMMON FORMS OF ACYANOTIC CONGENITAL HEART DISEASE

FA 2012: 284.1 • FA 2011: 258.1 • FA 2010: 254 • ME

3e: 254

CARDIO6_2c- 3

Abnormal Splitting of the Second Heart Sound (S2)

FA 2012: 284.1 • FA 2011: 258.1 • FA 2010: 254 • ME

3e: 255

CARDIO6_4- 1

Auscultation of Heart Murmurs

FA 2012: 285.1 • FA 2011: 259.1 • FA 2010: 255 • ME

3e: 234

- Best heard: upper right sternal border

- Radiates to: carotid arteries

- Sign: pulsus parvus et tardus

CARDIO6_7a- 1

Forms of Acyanotic Congenital Heart Disease

FA 2012: 285.1 • FA 2011: 259.1 • FA 2010: 255 • ME

3e: 231

CARDIO6_8a- 1

National Institute of Health, commons.wikimedia.org, Used With permission

FA 2012: 285.1 • FA 2011: 259.1 • FA 2010: 255 • ME

3e: 231

CARDIO6_9a- 1

Aortic Insufficiency (Regurgitation)

Features:

- Diastolic flow murmur

- Best heard: lower left sternal border

- Wide pulse pressure

- Bounding pulses

- Causes: HTN (most common), RF, IE

FA 2012: 285.1 • FA 2011: 259.1 • FA 2010: 255 • ME

3e: 247

CARDIO6_11a- 1

Ductus Arteriosus

FA 2012: 285.1 • FA 2011: 259.1 • FA 2010: 255 • ME

3e: 254

CARDIO6_12- 1

S3

FA 2012: 285.1 • FA 2011: 257.1 • FA 2010: 253 • ME

3e: 244

CARDIO6_12c- 1

S4

FA 2012: 285.1 • FA 2011: 257.1 • FA 2010: 253 •

ME 3e: 244

CARDIO6_12e- 1

Auscultation of Heart Murmurs

FA 2012: 285.1 • FA 2011: 259.1 • FA 2010: 255 • ME

3e: 247

CARDIO7.1-

Hypertension Basics

1 Majority of HTN is “essential” = idiopathic

2 Risk factors affect not only the risk of HTN, but affect the

first-line treatment

3 HTN is a problem because of its long-term consequences 

stroke, LVH, retinopathy, etc

FA 2012: 294.2 • FA 2011: 269.2 • FA 2010: 265 • ME

CARDIO7.2-

Angiogram of Renal Artery Stenosis

FA 2012: 294.2 • FA 2011: 269.2 • FA 2010: 265 • ME

CARDIO7.2-

FA 2012: 294.2 • FA 2011: 269.2 • FA 2010: 265 • ME

CARDIO7.3-

What’s Happening in Hypertension

1 Decreased number of arterioles

2 Increased arteriolar wall thickness

3 Increased total peripheral resistance

FA 2012: 294.2 • FA 2011: 269.2 • FA 2010: 265 • ME

CARDIO7.4-

Patrick J Lynch, commons.wikimedia.org, Used With Permission

Left Ventricular Hypertrophy Secondary To Longstanding HTN

FA 2012: 294.2 • FA 2011: 269.2 • FA 2010: 265 • ME

CARDIO7_5- 1

FA 2012: 294.2 • FA 2011: 269.2 • FA 2010: 265 • ME

3e: 264

Arteriolosclerosis and Onion-Skinning

Note the grossly thickened wall of this arteriole

Tdvorak; commons.wikimedia.org, Used With Permission

CARDIO7_5-

FA 2012: 294.4 • FA 2011: 269.4 • FA 2010: 265 • ME

CARDIO7_6-

Location of Aneurysms

FA 2012: 295.3 • FA 2011: 270.2 • FA 2010: 265 • ME

CARDIO7_6-

KGH, commons.wikimedia.org, Used With Permission

This is a section of aorta

that contains

myxomatous degeneration that led to

an aortic dissection

FA 2012: 295.3 • FA 2011: 270.2 • FA 2010: 265 • ME

CARDIO7_6-

J Heuser, commons.wikimedia.org, Used With Permission

Widened mediastinum seen on

Chest x-ray in aortic dissection

FA 2012: 295.3 • FA 2011: 270.2 • FA 2010: 265 • ME

CARDIO7_7-

When treating Hypertension, the USMLE often

asks, “What’s the drug of choice…”

• Essential hypertension?

• Diuretics (1st ine)

• ACE Inhibitors or ARBs

• Calcium channel blockers

• The Hypertensive CHF patient?

• : Diuretics (e.g furosemide, hydrochlorothiazide)

• The Hypertensive Diabetic?

• ACE inhibitors or ARBs (1st line): are reno-protective, slowing progression to

CARDIO7_7-

FA 2012: 306.2 • FA 2011: 280.2 • FA 2010: 276 • ME

CARDIO7_7-

Selectivity of Major Ca 2+ -Channel Blockers

FA 2012: 306.3 • FA 2011: 280.3 • FA 2010: 277 • ME

CARDIO7_7-

FA 2012: 306.2 • FA 2011: 280.2 • FA 2010: 277 • ME

α 1 - prazosin,terazosin,doxazosin

α 2 - mirtazapine

Blocks α 1 receptors on arterioles and venules and/or α 2 receptors in the

CNS

α 2 antagonists: used to treat depression

Non-selective antagonists: used to treat pheochromocytoma

α 1 antagonists: used to treat benign prostatic hyperplasia

CARDIO8_2- 1

Overview of Lipoprotein Metabolism

FA 2012: 120.1 • FA 2011: 114.1 • FA 2010: 114 • ME

3e: 53

Form micelles around dietary lipids to facilitate absorption of fats, cholesterol,

and fat-soluble vitamins

Synthesis

primary bile salts

primary

bile salts

glycine / taurine conjugation liver

hepatocytes

Brief Review of Bile:

cholesterol bile acids primary

secondary bile salts gut

bacteria