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Endocarditis | Masses | PE
Two of the suggested targets of the focused cardiac ultrasound (FoCUS) involve the detection of large intracardiac masses which makes reference to large valve vegetations or visible intracardiac or inferior vena cava thrombi. The second portion is the detection of valvular abnormalities recognizable with FoCUS (without the use of Doppler-based techniques) which entail leaflet or cusp massive disruption or marked thickening, flail, or anatomic gaps. Here we focus on the detection of visible vegetations or masses and the use of FoCUS in the management of patients with pulmonary embolism.
Endocarditis and Masses
Infective endocarditis can be recognized as masses arising from upstream valvular structures. This means that they would appear on the atrial side of the atrioventricular valve. While a large vegetation may be easy to spot on 2D ultrasound, another smaller mass and it associated functionality deficit (valve failure or surrounded support) may be difficult to see on FoCUS. The general recommendation is that if there is clinical suspicion and on examination there is a nondiagnostic screening study, proceeding with a comprehensive examination would be prudent. Our primary goal is to screen for catastrophic or severe failure of the valve on 2D imaging. These can be seen as large oscillating masses on a valve or its supporting structure or on a foreign device
Endocarditis could be mistaken in patients who have Lambl's excrescences (idiopathic linear mobile structures on the downstream side of AV), previously treated infective endocarditis and nonbacterial thrombotic endocarditis (secondary to antiphospholipid syndrome, SLE and others). It may not be straightforward to distinguish infective endocarditis from one of these. If there is clinical suspicion for endocarditis, further examination may include Transesophageal Echocardiography (TEE) which improves the image resolution when interrogating the valve
Normal Parasternal Long Axis View
On this view we can appreciate a large mass that appears attached to the posterior mitral valve and on the atrial side of the valve. On this clip it is difficult to differentiate morphologically between the valve and the mass. This mass is also attached to the base of the valve.
On the following clips we can appreciate normal findings with that of a patient who has a pacemaker wire. On the wire there is a mass or thrombus that move in and out of right atrium and ventricle. This is more apparent on the apical 4 chamber view below.
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Masses. Clips 1 and 3 act as reference. Clips 2 and 4 with a mobile mass on the RV.
On the IVC view below (Clip 2), we can observe a mass or thrombus on the right atrium with a dilated and barely collapsible IVC. This mass also appears mobile. Compare that to an IVC view without a mass in Clip 1 below:
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The following masses are attached to the inter atrial septum (IAS). The first one has small mass attached to the right atrial IAS with echogenic filamentous structures that arise from the mass and extend a few cm towards the tricuspid valve and are mobile (Clip 1). The tricuspid valve on this clip also appears thickened. Clip 2 has a large LA mass attached to the IAS that appears to be a tumor and does not seem to be affecting the functionality of the mitral valve.
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Pulmonary Embolism
Pulmonary embolism (PE) has a wide variety of presenting features, ranging from asymptomatic to shock or sudden death. It can be broadly classified as either massive or submassive. Patients with massive PE usually present with hemodynamic instability and are treated with either thrombolytic therapy or pulmonary embolectomy, while patients with submassive PE are generally hemodynamically stable that may or may not have right ventricular dysfunction (RVD) and are medically managed.
The diagnostic approach to a suspected PE includes a combination of clinical, pretest probability assessments, labs and definitive diagnostic imaging. There are also prognostic models that facilitate the decision making process to triage patients according to severity and estimate mortality. The role of echocardiography for screening for and prognostication of PE continues to evolve in this regard. Essentially, for patients who are present hemodynamically stable echocardiography has no role in the decision making process. These are based on society recommendations (European Society of Cardiology and the American College of Chest Physicians) although the American Society of Echocardiography does advise its use for PE risk assessment. The story is different for those who are unstable.
Among patients who present with PE induced hemodynamic instability, the 30-day all cause mortality is as high as 22%. It is the RV dysfunction that was thought to be a cause of death in patients with acute PE. Echocardiography has a role here. If patients remain unstable (SBP <90 mmHg for >15min, requiring vasopressors or clear evidence of shock) in spite of initial efforts and who is unable to tolerate CTPA, bedside echocardiography has a role. The idea here is to have a presumptive diagnosis of PE with the following findings of RVD and retain high specificity and thus are used to rule in PE:
1. Right heart thrombus: Present in up to 4% of cases but implies up to 40% mortality.
2. McConnell's sign: Regional wall abnormalities that spare the RV apex. This sign has the highest positive likelihood ratio (7.3) and implies a moderate to high post test probability of PE (an increase of up to 45% from pretest).
3. Paradoxical septal movement.
4. RV free wall hypokinesis/ enlargement. RV end diastolic diameter has a slight to moderate increase in the post test probability of PE. This sign is NOT sensitive enough to rule out PE. However its negative likelihood ratio (0.25) implies a lower post test probability (30% decrease from pretest).
Here we will compare normal FoCUS findings to those of patients with a high likelihood of PE.
Mc Connell's sign
-Enlarged RV. The RV is bigger in size than the LV
-McConnell's sign: RV free wall is hypokinetic but the apex is not.
-On diastole the septum is pushed towards the LV indicating volume overload.
-Enlarged RA
Large RV size
-Enlarged RV. The RV is bigger in size than the LV
-On diastole the septum is pushed towards the LV indicating volume overload.
-Enlarged RA
Paradoxical Septal Motion
-Enlarged RV. The ratio of end diastolic RV to LV is >1.
-Depressed RV
-On diastole the septum is pushed towards the LV indicating fluid overload.
Clot in transit
-On these clips we can see a thrombus that comes in and out of the RV and appears attached to the tricuspid valve.
-The second clip is a Parasternal short axis view that is out of the scope of FoCUS
Clot in transit 2
On these clips we can see a freely mobile thrombus on the RA.
References
1. Dabbouseh NM, Patel JJ, Bergl PA Role of echocardiography in managing acute pulmonary embolism Heart 2019;105:1785-1792.
2. Cho, J.H., Kutti Sridharan, G., Kim, S.H. et al. Right ventricular dysfunction as an echocardiographic prognostic factor in hemodynamically stable patients with acute pulmonary embolism: a meta-analysis. BMC Cardiovasc Disord 14, 64 (2014). https://doi.org/10.1186/1471-2261-14-64
3. Fields JM, Davis J, Girson L, Au A, Potts J, Morgan CJ, Vetter I, Riesenberg LA. Transthoracic Echocardiography for Diagnosing Pulmonary Embolism: A Systematic Review and Meta-Analysis. J Am Soc Echocardiogr. 2017 Jul;30(7):714-723.e4. doi: 10.1016/j.echo.2017.03.004. Epub 2017 May 9. PMID: 28495379.