Cardiac Tamponade

Question 1

Causes of cardiac tamponade?

Answer 1

Post-cardiac surgery

Post-percutaneous intra-cardiac procedures
Traumatic
Inflammatory
Infectious
Autoimmune
Neoplastic
Metabolic

Question 2

How common are post-cardiac surgery pericardial effusions?

Answer 2

Very common

Commonly located posteriorly; difficult to assess on TTE

Commonly appear on post-op day 2 and reach maximal size by day 10

Most resolve on their own; 0.2 —> 8.4% develop tamponade

Question 3

Risk factors for tamponade after cardiac surgery?

Answer 3

Use of anticoagulants

Pts w/coag disorders

Excessive bleeding from mediastinum

Question 4

How much blood around the pericardial sac can theoretically cause tamponade?

Answer 4

As little as 100 cc

Question 5

During percutaneous intracardiac procedures; how does tamponade occur?

Answer 5

Occurs via direct cardiac perforation from guidewires, catheters, dilators etc, in setting of anticoagulation

Question 6

During penetrating trauma, most frequent location for cardiac injury is;

Answer 6

RV (45%)

LV (35%)

RA (15%)

Question 7

What ate some autoimmune and inflammatory conditions that can lead to cardiac tamponade?

Answer 7

SLE

Behcet syndrome

Systemic vasculitis

Question 8

Metabolic causes of tamponade?

Answer 8

Uremia from renal failure

Myxedema from hypothyroidism

Question 9

Sx and symptoms of cardiac tamponade?

Answer 9

Hypotension

Tachycardia

Dyspnea

Chest pain

Elevated JVD

Question 10

Normal pericardium;

Answer 10

Made up of two collagen layers; visceral/parietal

Houses normal physiologic fluid 15-50 cc normally

Aids interplay between atria/ventricles; reduces friction with surrounding organs

Is also a barrier to bacterial invasion/infection

Question 11

Pathophys of cardiac tamponade;

Answer 11

Occurs when filling pressure in pericardial sac equals or exceeds filling pressures of the heart

Normally when pericardial pressures > 15-20 have been reported, tamponade occurs

Question 12

What is ventricular interdependence?

Answer 12

Hemodynamics of left and right heart are directly influenced by each other to a greater degree than normal

Question 13

What are some physiological responses to tamponade?

Answer 13

Increased sympathetic response —-> tachycardia, diastolic relaxation, peripheral vasoconstriction, and inotropy to maintain CO

Question 14

What are the phases of cardiac tamponade?

Answer 14

1——> effusion is present, and it causes increasing pericardial, RV, LV pressures; but no equalization of pressures seen yet; NO hemodynamic compromise is present at this time

2——> RV filling pressure and intra-pericardial pressures are equal; CO starts to decrease, signs of tamponade on ECHO are evident, pts experience pulsus paradoxes at this stage (fall in SBP during inspiration by >10 mmHg)

3—-> Complete equalization of pressures, severe decrease in CO, corresponding to circulatory collapse/shock

Question 15

Beck’s triad;

Answer 15

JVD

Muffled heart sounds

Hypotension

Question 16

What is pulsus paradoxus seen with cardiac tamponade?

Answer 16

Exaggerated respiratory variability in blood pressure resulting from ventricular interdependence

SBP variability > 10 mmHg with inspiration

Analysis of SBP variation on arterial waveform is superior to auscultation

Question 17

With tamponade what do we see with the central venous pressure waveform?

Answer 17

CVP is elevated; see JVD

CVP waveform will show a decrease or loss of the Y descent due to decreased RV filling

Question 18

Most specific sign of cardiac tamponade on EKG?

Answer 18

Electrical alternans

(Alteration in QRS amplitude as the heart beats against fluid)

Question 19

What do we see on X-ray with suspected cardiac tamponade?

Answer 19

Bottle-shaped heart

Question 20

Primary imaging modality used in diagnosis of cardiac tamponade?

Answer 20

ECHO

Provides rapid diagnosis; nearly 100% accurate

Question 21

What are some signs on ECHO that point towards diagnosis of tamponade?

Answer 21

Large effusion

Swinging motion of the heart

Septum shifts toward L-ventricle during inspiration

Collapse of both atria/ventricles

Dilated IVC

Question 22

Cardiac tamponade can be classified as small, moderate, large based on size of fluid accumulated;

Answer 22

Small; <100

Moderate; 100- 500

Large ; >500

Question 23

Which chamber of the heart is the first to collapse due to a cardiac tamponade?

Answer 23

RA

Has the smallest chamber pressures in the heart (0-5mm Hg)

Question 24

Best view to see right atrial collapse on echo due to cardiac tamponade?

Answer 24

Apical four chamber view or sub costal view

Question 25

After RA collapse due to tamponade, the RV starts to collapse next;

Answer 25

Para-sternal long axis views are the best views for assessing RV collapse

RVOT is most compressible part of RV

Question 26

Do we see LA/LV collapse with cardiac tamponade on echo?

Answer 26

Rarely

LV is stiff

LA collapse can be seen in 25% of pts

Question 27

What are differences in transvalvular flow velocities?

Answer 27

There are normal respiratory variations in flow across the valves of right/left side of heart

During inspiration; increased venous return to right side of heart causes increases flow across the tricuspid and pulmonic valves

At the same time, during inspiration, left side of heart has decreased venous return from pulmonary veins leading to a decreased flow across the aortic/mitral valves

Ventricular interdependence in cardiac tamponade exaggerates these normal variations with inspiration;

**increase in flow across tricuspid valve >45% is indicative of cardiac tamponade

** decrease in flow across mitral valve 20-40% is indicative of tamponade