Test 2 Flashcards by John Goodman

What is the normal time range for a PR interval?

120 - 200 ms

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What is the normal time range for a QRS complex?

80 - 120 ms

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What is the normal time range for an ST segment?

<120 ms

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What is the normal time range for QT interval?

330 - 350 ms

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What is the normal time range for QTc?

QT/√RR = ~440 ms

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How long (time) is one big box on an ECG rhythm strip?

1 big box = 0.2 seconds = 200 ms

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How long (time) is one small box on an ECG rhythm strip?

1 small box = 0.04 seconds = 40 ms

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What are the 3 requirements for normal sinus rhythm?

1) HR is between 60 - 100 bpm
2) P wave is positive in lead II and negative in aVR
3) 1:1 P to QRS

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What is the big box and divide rule for determining regular rhythm on an ECG?

300 / #big boxes

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What is the 2nd big box rule for determining regular rhythm on an ECG?

For normal rhythms:

1 big box = 300 bpm
2 big box = 150 bpm
3 big box = 100 bpm
4 big box = 75 bpm
5 big box = 60 bpm
6 big box = 50 bpm

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What is small box and divide rule for determining regular rhythm on an ECG?

1500 / #small boxes

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What is the method for analyzing an ECG?

1) rate
2) rhythm
3) axis

Do it the same way EVERY time!!!

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What are the bipolar leads?

I, II, III

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What re the unipolar leads?

aVF, aVR, aVL

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What are the precordial leads?

V1 - V6

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What plane do the bipolar and unipolar leads record?

Voltage from a frontal plane

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What plane do the precordial leads record?

Voltage from a horizontal plane

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How does an ectopic pacemaker change the direction of the P wave in lead II and aVR?

downward in lead II
upward in aVR

explanation:
ectopic pacemaker: atrial depolarization must spread up the atria in a retrograde direction, which is just the opposite of what happens with normal sinus rhythm. Therefore, an arrow representing the spread of atrial depolarization with AV junctional rhythm points upward and to the right , just the reverse of what happens with normal sinus rhythm.

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Define inotropy

contractility

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what is an inotrope?

a substance that increases contractility

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What is contractility? What is contractility dependent upon?

the property of myocardial cells to develop a force at a given muscle cell length.

1) the size of the inward calcium current at the L-type channels
2) the amount of calcium stored in the sarcoplasmic reticulum

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How do beta-1 receptors affect contractility?

activation of adenylyl cyclase leads to:

1) phosphorylation of sarcolemmal (membrane) Ca2+ channels, which leads to an increase in Ca2+ influx
2) phosphorylation of SERCA pumps, leading to an increase of Ca2+ storage in SR

Define chronotropy

Chronotropy is conduction rate, which controls heart rate

What is a chronotrope?

Substance that increases heart rate

What does elevated plasma norepinephrine indicate in HF

marker of poor prognosis

What is B-type natriuretic peptide? Typically, what is BNP a marker for?

Acts as a vasodilator that is released from the myocardium in HF in response to increases in wall tension and wall stretch in the ventricles to counteract RAAS and SNS effects in HF BNP is a marker for fluid overload

What is C-reactive protein (CRP)? What is the prognosis of high levels of CRP in patients with heart failure?

Measures the general level of inflammation in the body worse prognosis

Define dilated cardiodiomypathy and explain it on a pathophysiological level

dilation of the ventricles and depressed contractility pathophysiologic level: myocyte apoptosis and necrosis, fibrosis, and neurohormonal upregulation

Define hypertrophic cardiomyopathy

myocardial hypertrophy in the absence of a recognized stimulus such as systemic hypertension or aortic stenosis

Define restrictive and infiltrative cardiomyopathy

increased fibrosis of the ventricular myocardial wall, resulting in increased stiffness. This prevents diastolic relaxation causing decreased ventricular filling

define orthopnea

SOB when lying flat

What pathologic condition is a RSR' pattern in precordial lead V1 indicative of?

Right bundle branch block. Bunny ears in V1 = RBBB

What pathologic condition is a rS pattern in lead V1 indicative of?

Left bundle branch block

Describe the NYHA functional classes of heart failure.

Class 1: no limitation when active Class 2: mild limitations when active Class 3: marked limitations when active but comfortable at rest Class 4: unable to carry out any activity without symptoms of heart failure

Name normal pressures for the right atrium, right ventricle, pulmonary artery, and pulmonary capillary wedge.

``` in mmHg... RA: 2-8 RV: 15-30 / 2-8 Pulmonary artery: 15-30 / 4-12 PCWP: 2-10 ```

What is the equation for calculating SVR?

SVR = (MAP - RA) / CO x 80

What is the normal range for SVR?

800-1200 dynes/sec/cm

What is the Fick equation for calculating cardiac output?

CO = VO2 / CaO2 - CVO2 VO2 is oxygen consumption by the tissue CaO2 is arterial oxygen content CVO2 is venous oxygen content

What is a normal MVO2?

75%

What happens to MVO2 when cardiac output increases?

MVO2 increases as well

What is a S4 gallop a marker of?

Diastolic dysfunction

What are some causes of intranodal block?

``` Increased vagal tone (music notes) Beta blockers (music notes) calcium channel blockers (music notes) conduction defects hyerkalemia (prevents nodes from firing) ```

What are some causes of infranodal block?

infiltrative diseases MI iatrogenic (after ablation surgery) fibrosis/scarring

What are the 3 characteristics of 3rd degree AV block

bradycardia complete AV dissociation (P and QRS) Atrial rate > ventricular rate

Name 3 drugs/classes of drugs that can cause sinus bradycardia

beta blockers calcium channel blockers digoxin

Name 3 drugs/classes of drugs that can cause sinus tachycardia

Atropine vasodilators sympathomimetics

What are some causes of sinus dysfunction

Drugs (class II and IV) aging cardiomyopathies

What should be your first suspicion when a patient presents with bradycardia?

medications

What drugs treat for A-fib and A-flutter?

Class II, IV, digoxin

Other than rate controlling drugs, what type of drug is indicated in a patient with A-fib or A-flutter?

thrombotic prophylaxis

What does a depressed ST segment in tachycardia indicate?

AVRT depression is depolarization of the atria (inverted P wave)

What genetic mutations are associated with hypertrophic cardiomyopathy?

beta myosin heavy chain myosin binding protein C

What genetic mutation is associated with dilated cardiomyopathy?

mutations in the titin protein gene