Cardiac Monitoring (6/17/25) Flashcards
(144 cards)
1
Q
What do bipolar limb leads use in ECG monitoring?
A
Two electrodes—1 positive and 1 negative—forming Einthoven’s triangle.
2
Q
What are the augmented limb leads and their placements?
A
AVR (right arm), AVL (left arm), AVF (left foot); these are unipolar leads that intersect limb leads.
3
Q
What does a 12-lead ECG help identify?
A
Rhythm, conduction delays, infection, myocardial damage.
4
Q
What ECG finding suggests a right bundle branch block (RBBB)?
A
R/R1 pattern and QRS duration > 0.12 seconds.
“Rabbit Ears”
look at V1
5
Q
What ECG finding is seen in left bundle branch block (LBBB)?
A
QRS > 0.12 seconds; may mimic anteroseptal MI.
Look at V1
Huge “S”
Negative “R” deflection
6
Q
How is right atrial hypertrophy diagnosed on ECG?
A
Initial P wave in V1 is larger; P wave height > 2.5 mm in any limb lead.
7
Q
What causes left atrial hypertrophy?
A
Mitral valve disease, systemic hypertension, and other causes of LVH.
8
Q
What ECG findings indicate LVH?
A
Deep S in V1 and tall R in V5. S + R > 35 mm.
9
Q
What signifies myocardial ischemia on ECG?
A
Inverted, symmetrical T waves in 2 contiguous leads.
10
Q
What ECG change signifies acute myocardial injury?
A
ST segment elevation in 2 contiguous leads.
11
Q
How is an old infarction diagnosed on ECG?
A
Presence of a significant Q wave: ≥1 mm wide or 1/3 QRS height in 2 contiguous leads.
12
Q
What are the main components of an artificial pacemaker?
A
Generator, lead wire, and electrode.
13
Q
What is a unipolar pacemaker lead configuration?
A
The negative electrode is in the heart chamber and the positive (grounding) electrode is outside the heart; more sensitive to EMI.
14
Q
What is a bipolar pacemaker lead configuration?
A
Both electrodes are located in the chamber being paced; less sensitive to EMI and uses less energy.
15
Q
What is a multipolar pacemaker lead?
A
A lead with multiple electrodes in one lead capable of pacing multiple chambers.
16
Q
What is ‘triggered’ pacing mode used for?
A
The pacemaker fires when intrinsic activity is sensed; currently only used in device testing.
17
Q
What parameters can modulate pacemaker rate?
A
Vibration, motion, minute ventilation, right ventricular pressure.
18
Q
How does an ICD distinguish VT/VF from SVT?
A
Based on onset (abrupt vs gradual), R-R interval variability, QRS width, and amplitude.
19
Q
What does the pacemaker code ‘DDD’ indicate?
A
Dual pacing and sensing in both atria and ventricles; can inhibit or trigger based on intrinsic activity.
20
Q
What perioperative step is critical for AICD/BiV patients?
A
Interrogation of the device postoperatively and availability of back-up pacing.
21
Q
Why should bipolar cautery be used in AICD/BiV patients?
A
To direct current between electrodes and minimize EMI.
22
Q
What are common uses for central venous pressure (CVP) monitoring?
A
Volume status, right heart function, drug/fluid administration, air embolism aspiration.
23
Q
Normal CVP range in a spontaneously breathing patient?
A
1–7 mmHg.
24
Q
What does the ‘a wave’ in a CVP waveform represent?
A
Atrial contraction; occurs after the P wave.
25
What does the 'c wave' represent in CVP?
- Tricuspid valve closes
- isovolumetric contraction of ventricle
- Tricuspid valve and ventricles bulging into the atrium
- Follows "R" wave
26
What is the 'x descent' in CVP?
- Atrial pressure falls during atrial relaxation
- downward displacement of tricuspid valve due to RV contraction
- Systolic collapse
27
What causes the 'v wave' in CVP waveform?
Venous filling of the atrium during late systole
Tricuspid valve remains closed
Peaks just after "T" (ventricular repolarization)
28
What causes the 'y descent' in CVP?
- Opening of the tricuspid valve and passive filling of the right ventricle
- Diastolic collapse
29
What is the CVP waveform change seen in tricuspid regurgitation?
Absence of x descent due to valve incompetence.
30
What happens to the CVP waveform in atrial fibrillation?
Absence of a wave and possibly larger c wave.
31
Why should PAC be placed in West Zone 3 of the lung?
To ensure uninterrupted pulmonary capillary blood flow for accurate wedge pressure readings.
32
What are the standard PAC insertion depths?
RA: 20–25 cm
RV: 30–35 cm
PA: 40–45 cm
wedge: 45–55 cm.
33
What does a slurred early y descent in PA waveform indicate?
Mitral stenosis.
34
What causes tall a waves in PAWP waveform?
Acute LV infarction causing a non-compliant left ventricle.
35
What is stroke volume variation (SVV) and what does a value >10% suggest?
It reflects preload responsiveness; >10% suggests hypotension will likely respond to fluid.
36
What factors affect the accuracy of pulse contour analysis?
Atrial fibrillation, arterial line site, waveform quality, vasopressors, and need for frequent calibration.
37
How many views are used in a FoCUS echocardiography exam?
Five key views are used compared to 28 in a comprehensive exam.
38
How is TTE image orientation different from TEE?
In TTE, anterior structures appear at the top; in TEE, posterior structures are at the top.
39
What view is best for assessing IVC size and collapsibility?
Subcostal IVC view during spontaneous respiration.
40
What is an ECG finding of left atrial hypertrophy (LAH)?
The terminal portion of the diphasic P wave in lead V1 is enlarged (downward deflection)
41
What are the ECG findings of right ventricular hypertrophy (RVH)?
* QRS complex is **positive in lead V1**
* **R waves decrease in amplitude** across the chest leads (V1 to V6)
* Indicates **increased depolarization toward V1** due to thickened RV wall
42
What are common causes of right ventricular hypertrophy (RVH)?
* **Chronic obstructive pulmonary disease (COPD)**
* **Pulmonary hypertension (Pulm HTN)**
* Other **primary pulmonary diseases**
43
What are common causes of left atrial hypertrophy (LAH)?
* **Mitral valve disease** (especially mitral stenosis)
* **Systemic hypertension**
* All causes of **left ventricular hypertrophy (LVH)**
44
What are common causes of left ventricular hypertrophy (LVH)?
* **Systemic hypertension (HTN)**
* **Congestive heart failure (CHF)**
* **Aortic valve disease**
* **Coarctation of the aorta**
Severe anemia as well
45
Which ECG leads correspond to the inferior wall of the heart?
Leads II, III, and aVF
## Footnote
Reflect right coronary artery (RCA) distribution
46
Which ECG leads correspond to the anterior wall of the heart?
Leads V3 and V4
## Footnote
Reflect left anterior descending artery (LAD) territory
47
Which ECG leads reflect the septal region of the heart?
Leads V1 and V2
## Footnote
Also supplied by the LAD, specifically the septal branches
48
Which leads represent the lateral wall of the heart?
Leads I, aVL, V5, and V6
## Footnote
Reflect perfusion by the left circumflex artery (LCx)
49
What are the high lateral ECG leads?
Leads I and aVL
50
What are the low lateral ECG leads?
Leads V5 and V6
51
Which leads are considered the anterior-septal leads?
Leads V1 through V4
## Footnote
Encompass the septal and anterior walls
52
Which artery is typically involved in changes seen in leads V1–V4?
The left anterior descending (LAD) artery
53
What ECG leads might show reciprocal changes in an inferior MI?
Leads I and aVL may show ST depression
## Footnote
(reciprocal to inferior ST elevation)
54
What ECG leads might show reciprocal changes in an anterior MI?
Inferior leads (II, III, aVF) may show ST depression
55
What ECG finding indicates an old myocardial infarction?
A significant Q wave, which indicates myocardial necrosis
56
What makes a Q wave significant in diagnosing an old infarct?
It must be ≥1 mm wide or at least 1/3 the height of the QRS complex. Must appear in two contiguous leads.
57
What does loss of R wave progression on an ECG suggest?
It may indicate a prior anterior myocardial infarction
58
What does the generic pacemaker code consist of?
A 5-letter code representing the pacemaker’s function, usually simplified to the first three positions:
1. Chamber Paced
2. Chamber Sensed
3. Response to Sensing
(4th: Rate Modulation; 5th: Multisite Pacing)
59
What do the letters in the pacemaker code stand for (positions 1–3)?
**Position 1 (Chamber Paced):**
A = Atrium, V = Ventricle, D = Dual, O = None
**Position 2 (Chamber Sensed):**
A = Atrium, V = Ventricle, D = Dual, O = None
**Position 3 (Response to Sensing):**
I = Inhibited
T = Triggered
D = Dual (I + T)
O = None
60
What does “Inhibited” mode mean in pacemaker function?
If intrinsic electrical activity is sensed, the pacemaker does not fire.
* Prevents unnecessary pacing.
61
What does “Triggered” mode mean in pacemaker function?
If intrinsic activity is sensed, the pacemaker delivers a paced beat in response.
* Rarely used today; primarily in testing devices.
62
What does “DDD” pacemaker mode mean?
Dual chamber paced, dual chamber sensed, and dual response to sensing.
* Allows for synchronized pacing and sensing in both atrium and ventricle.
63
What does the 4th position in the pacemaker code indicate?
Rate modulation:
* R = Rate-responsive (adjusts pacing rate based on physical activity)
* O = No rate modulation
64
What does the 5th position in the pacemaker code indicate?
Multisite pacing:
* Used for cardiac resynchronization therapy (CRT)
* Paces multiple chambers (e.g., both ventricles)
65
What is Bi-Ventricular Pacing (Bi-V Pacing)?
A form of cardiac resynchronization therapy (CRT).
Involves pacing three chambers: the right atrium and both ventricles (via a lead placed in the coronary sinus for LV access).
66
What is the purpose of Bi-V Pacing?
To synchronize ventricular contraction and improve cardiac output. Especially useful in patients with bundle branch block (BBB) and ventricular dyssynchrony.
67
How does Bi-V Pacing improve heart function?
Improves right and left ventricular activation timing.
Increases left ventricular ejection fraction (EF) and reduces symptoms of heart failure.
68
What are the clinical indications for Bi-V Pacing?
Moderate to severe heart failure (NYHA Class III or IV).
EF ≤ 35%.
Intraventricular conduction delays (e.g., QRS ≥ 120 ms).
Failure of medical therapy to relieve symptoms.
H/o cardiac arrest
69
What is the typical QRS duration cutoff for considering Bi-V Pacing?
A QRS duration ≥ 120 milliseconds is typically required.
70
What is the benefit of Bi-V Pacing in heart failure patients?
Improved exercise tolerance, reduced hospitalizations, and better survival. Often leads to reverse remodeling of the heart.
71
What is the effect of placing a magnet over a pacemaker?
Switches the device to **asynchronous pacing**
* No longer responds to intrinsic activity (e.g., **DOO or VOO modes**)
* **No rate modulation**
72
How does a magnet affect an implantable cardioverter-defibrillator (AICD)?
**Disables anti-tachycardia therapy**
* **Prevents inappropriate shocks**
* Does **not affect pacing function**
73
How is battery life assessed using a magnet in AICD/PM devices?
Causes a **predictable change in pacing rate or pulse width**
* A **decrease in amplitude or width** may indicate **inadequate capture**
74
What is the follow-up schedule for devices at end-of-life battery status?
Requires **intensified monitoring**, typically **every 4 weeks**
* An **elective replacement** is scheduled before complete depletion
75
What is the primary function of an implantable cardioverter-defibrillator (ICD)?
It is a battery-powered device designed to detect and terminate ventricular fibrillation (VF) or ventricular tachycardia (VT).
76
How does an ICD detect arrhythmias?
It measures R-R intervals (time between ventricular depolarizations). Short intervals may indicate VT/VF, but can also be due to SVT (10% of shocks are inappropriate).
77
What is asynchronous pacing?
A pacemaker mode that delivers electrical impulses at a fixed rate, regardless of the heart's intrinsic activity.
78
What are common modes of asynchronous pacing?
Common modes include VOO, AOO, and DOO.
79
When is asynchronous pacing used?
It is used during surgery, with magnet application, or in pacemaker-dependent patients.
80
What is a risk associated with asynchronous pacing?
It may cause the R-on-T phenomenon and induce arrhythmias if the patient has underlying rhythm.
81
What CVP waveform changes are seen in tricuspid stenosis?
Tall "A" wave due to increased resistance to right atrial emptying during atrial contraction.
## Footnote
The y descent is delayed or blunted because blood flow into the right ventricle is obstructed by the stenotic valve.
82
Where is central venous pressure (CVP) measured (anatomically)?
at the junction of the superior vena cava and the right atrium.
83
What influences central venous pressure (CVP)?
CVP is highly dependent on intravascular volume status and venous tone (vascular compliance).
84
What is the typical catheter depth for CVP placement via the right internal jugular (RIJ) vein?
15 cm is typically sufficient to place the catheter tip at the SVC–RA junction.
85
What is the typical catheter depth for CVP placement via the left internal jugular (LIJ) vein?
18 cm is usually required due to the longer and more circuitous route to the SVC–RA junction.
86
What is the typical catheter depth for CVP placement via the right subclavian vein?
Around 14 cm, depending on patient size and insertion angle.
87
What is the typical catheter depth for CVP placement via the left subclavian vein?
Approximately 17 cm, again due to the longer path to the SVC–RA junction.
88
What does the most distal lumen of a pulmonary artery catheter (PAC) measure?
It measures **pulmonary artery pressure (PAP)**
89
What is the purpose of the lumen located ~30 cm proximal to the PAC tip?
It measures **central venous pressure (CVP)**
90
What is the function of the 3rd lumen in a PAC?
It connects to a **balloon near the tip** of the catheter, which is used to obtain a **wedge pressure** (PAOP)
91
What does the 4th lumen near the balloon contain?
It houses a **temperature thermistor**, used for **thermodilution cardiac output measurements**
92
What is the preferred site for pulmonary artery catheter (PAC) insertion?
Right internal jugular (RIJ) vein
93
What is the initial advancement method for PAC insertion?
Insert with the balloon deflated until the catheter reaches the right atrium
Advance during contraction
94
RA
95
RV
96
PA
97
Wedge
98
What common dysrhythmias may occur during PAC insertion? Are they complications?
* PVCs and ventricular tachycardia are common during insertion
* Often transient and not considered true complications unless sustained
99
What conduction abnormalities can PAC placement cause?
* Transient right bundle branch block (RBBB)
* Rarely, can cause complete heart block (especially in patients with preexisting LBBB)
100
What mechanical complication can occur with PAC insertion and why must it be avoided during surgery?
* Catheter knotting
* Ensure free movement of the catheter before chest closure in right-heart surgeries
101
What are signs of pulmonary infarction from PAC use?
* Can occur due to prolonged wedge or balloon inflation
* May lead to pulmonary artery rupture, hemoptysis, and hypotension
102
What are infectious and structural complications of PAC use?
* Endocarditis (infectious)
* Valve injury (structural)
103
What are the initial steps in managing a pulmonary artery rupture from a PAC?
Ensure adequate oxygenation.
Perform endobronchial intubation (single or double lumen tube) to isolate the bleeding lung.
104
How can PEEP help in managing pulmonary artery rupture?
Apply positive end-expiratory pressure (PEEP) to tamponade bleeding and improve oxygenation.
105
What medical therapies may be needed during pulmonary artery rupture?
Reverse anticoagulation (if not on bypass).
Use bronchoscopy to help localize and control bleeding.
106
What catheter maneuvers may help in pulmonary artery rupture management?
Either float the balloon into the site of rupture to tamponade it or withdraw the catheter carefully depending on the situation.
107
What are the definitive surgical options for pulmonary artery rupture?
Oversewing the pulmonary artery.
Lobar resection if necessary.
108
What does pulmonary artery pressure (PAP) measure?
It reflects the **pressure within the pulmonary artery**, and is directly measured by the **distal lumen** of the PAC.
109
What does pulmonary artery wedge pressure (PAWP) indicate?
An **indirect measurement of left atrial pressure**. Obtained by inflating the PAC balloon and 'wedging' in a pulmonary artery branch.
110
What pressure can be used as an alternative to PAWP?
**Pulmonary artery diastolic (PAD) pressure**, when the wedge tracing is unreliable.
111
Where should the PAC tip be positioned for accurate wedge pressure readings?
In **West lung zone 3**, where pulmonary capillary pressure exceeds alveolar pressure, ensuring continuous blood flow.
112
Why is pulmonary artery wedge pressure (PAWP) a poor estimate of LVEDP in some patients?
Because PAWP may not accurately reflect LVEDP in conditions such as:
* Reduced left ventricular compliance
* Aortic regurgitation
* Positive end-expiratory pressure (PEEP)
* Ventricular septal defect (VSD)
* Mitral stenosis or regurgitation
113
What pulmonary artery waveform changes are seen in mitral regurgitation (MR)?
Tall V wave
C wave and V wave appear fused
Absent X descent
Severity of waveform change is not reliable for grading MR due to variations in left atrial compliance and volume.
114
What pulmonary artery waveform changes are seen in mitral stenosis?
* Slurred, early y descent due to obstructed left ventricular filling
* A wave may be absent because mitral stenosis is frequently associated with atrial fibrillation, which eliminates organized atrial contraction
115
What PAC waveform changes are seen in acute left ventricular myocardial infarction (MI)?
Tall a waves due to a non-compliant left ventricle.
## Footnote
Example: Increased a wave amplitude indicates elevated pressures in the pulmonary artery.
116
What effect does LV systolic dysfunction have on left ventricular end-diastolic volume (LVEDV) and pressure (LVEDP)?
LV systolic dysfunction increases left ventricular end-diastolic volume (LVEDV) and pressure (LVEDP).
## Footnote
Example: Elevated LVEDP can lead to pulmonary congestion.
117
What happens to pulmonary artery wedge pressure (PAWP) in acute left ventricular myocardial infarction (MI)?
Pulmonary artery wedge pressure (PAWP) is elevated.
## Footnote
Example: Elevated PAWP indicates increased left atrial pressure.
118
Fick Equation
SvO2 = SaO2 - VO2 /(CO x 1.34 x Hgb)
119
How does the thermodilution method measure cardiac output (CO)?
- A cold 10 mL bolus is injected into the RA lumen.
- A thermistor in the pulmonary artery detects the temperature change downstream.
- 3 averaged attempts are used.
- CO is inversely proportional to the degree of temperature change.
- A change ≥13% from baseline is considered significant.
## Footnote
Gold standard for CO measurement
120
What are common sources of error in thermodilution cardiac output measurements?
- Measures right heart output, but assumes left heart output is equal
- Intra-cardiac shunts (e.g. VSD) cause inaccurate values
- Tricuspid or pulmonic regurgitation affects accuracy
- Improper handling of injectate (wrong volume/temp)
- Temperature fluctuations (e.g., after bypass)
- Rapid fluid infusion or cold blood can distort the thermal signal
121
How does continuous cardiac output (CO) monitoring via PAC work?
A filament in the right ventricle intermittently releases small amounts of heat, which is detected by a thermistor downstream.
122
How often is CO updated in continuous monitoring via PAC?
Data is updated every 30–60 seconds and averaged over 3–6 minutes.
123
What is an advantage of continuous CO monitoring over thermodilution?
It has better reproducibility and precision.
124
What is a limitation of continuous CO monitoring in unstable patients?
It has delayed responsiveness, making it less reliable during acute hemodynamic changes.
125
In what condition is continuous CO monitoring more accurate than thermodilution?
During positive pressure ventilation.
126
What does pulse contour analysis use to estimate cardiac output (CO)?
It uses the **area under the curve (AUC)** from **arterial pressure tracings**.
127
What hemodynamic variables can pulse contour analysis estimate?
**Cardiac output**, **pulse pressure**, and **stroke volume variation (SVV)**.
128
What does a stroke volume variation (SVV) >10% suggest?
It indicates that **hypotension is likely to respond to fluid resuscitation**.
129
What does pulse contour analysis rely on to estimate stroke volume?
An **algorithm** analyzing pressure from **end-diastole to end-systole**, which incorporates **ventricular compliance**.
130
How accurate is pulse contour analysis compared to thermodilution?
It has a variability of about **±0.5 L/min** when compared to thermodilution CO.
131
What type of waves does echocardiography use to generate images?
High-frequency ultrasound waves
132
What determines the echogenicity of tissue in ultrasound?
The product of density × velocity of sound through tissue
133
What is M-mode echocardiography used for?
Uses narrow ultrasound beams to precisely measure tissue planes (e.g., ventricular wall thickness)
134
What is 2D echocardiography used for?
Produces real-time moving images
## Footnote
Used to visualize cardiac structure and function
135
What is Doppler echocardiography used for?
Measures speed and direction of blood flow
## Footnote
Uses color overlays to visualize flow patterns
136
What is evaluated in the parasternal short axis view?
Left ventricular (LV) function
Left ventricular volume assessment
137
What is assessed in the apical four-chamber view?
Right vs. left ventricular size
Tricuspid and mitral valve function
May also show the descending aorta
138
What does the parasternal long axis view evaluate?
LV size and function, Left atrium (LA), Aortic valve and aortic root, Mitral valve motion
139
What structures can be seen in the subcostal (subxiphoid) view?
IVC collapsibility (for fluid responsiveness), Four-chamber heart view (when transthoracic views are limited), Useful during CPR or when patient is supine
140
What does transesophageal echocardiography (TEE) offer that TTE may not?
High-resolution, posterior view of the heart, Better visualization in obese, ventilated, or surgical patients
141
What are common structures visualized with TEE?
Left atrial appendage (clot detection), Thoracic aorta, Valves and posterior cardiac structures
142
What are the clinical roles of transesophageal echocardiography (TEE)?
* Intraoperative monitoring
* Rescue tool for hemodynamic instability
* Valvular function assessment
* Intraoperative decision-making support
143
Why do posterior cardiac structures appear at the top of a TEE image?
Because the TEE probe sits behind the heart, posterior structures are closer to the transducer, so they appear at the top of the image.
144
What are key contraindications to TEE?
* Esophageal varices
* History of laparoscopic gastric banding or other significant esophageal pathology
