Echocardiography Imaging Windows - The Subcostal View

A Subcostal view is obtained by placing the probe 3-4 centimeters under the xiphoid. Echocardiographer should ask the patient to lie on his back and bend his knees, this relaxes the abdominal musculature and a better quality of images are obtained. 
This view is utilized in the immobile patients, patients suffering from COPD or in the patients on ventilatory support where parasternal view is not possible. 

The Four Chamber Plane of Subcostal view - In the four chamber plane the inferior surface of the right ventricle rests on the diaphragm. The echo beam reaches the heart through corner of the liver. The echo beam in this medium is perpendicular to the heart, so interatrial and interventricular septum are easily visualized. There are no drop outs of echo signals in this view as it happens in Apical 4 chamber view, that is why you can easily diagnose and evaluate interatrial and interventricular shunts. 

You can even differentiate among the following interatrial defects. 

• Defect in the area of Fossa Ovalis (Secundum Type)
• Lower defect which is extending upto Mitral Annulus ( Primum)
• Sinus Venosus defect which is located high in the roof of an Atria. 

The subcostal four chamber view allows to evaluate LV and RV functions as well as valve regurgitations.

Subcostal Inferior Venacava View

You can confirm the morphology of right atrium by tilting the plane inferiorly, this shows the inferior venacava entering into the right atrium. The inferior venacava is lateral and anterior to decending aorta. These two vessels can be distinguished by seeing the pulsation of aorta or by asking the subject to inhale which sucks the blood to the chest and as a result IVC collapses. This view also allows you to diagnose pericardial effusion because you can easily assess the degree of separation of heart from the pericardium. 

Subcostal Short Axis View - 

The short axis subcostal view is same as PSAX( Parasternal short axis view). One can obtain a short axis of the left ventricle. This view allows you to estimate function  of left ventricle and visualize aortic, pulmonic as well as  tricuspid valves. 

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Echocardiography Imaging Windows - The Apical 5 Chamber View

If you want to obtain a good apical 5 chamber view then first of all you need to have a high quality 4 chamber view. The fifth chamber of 5 chamber view is Aorta. 

What you have to do is to tilt your probe upwards from the position of 4 chamber view. By doing this you will not see RA and the tricuspid valve but the aorta will be visible in the middle of the screen. There are patients in whom you have to move the probe one intercostal space higher and more lateral. This will give a better alignment of your ultrasound beam with LV outflow tract. 

The main aim of the five chamber view is to display aortic valve and LVOT. This view helps an echocardiographer to assess aortic stenosis or regurgitation. You can also grade the severity of aortic valve lesions with the help of Doppler Imaging. The structure of the aortic valve is better visualized in parasternal view. 

Echocardiography Imaging Windows - The Apical 2 Chamber View

You can easily obtain an apical 2 chamber view from an apical 4 chamber view. The marker of the probe is rotated counterclockwise 90 degrees. To get a better image you can aim towards the left arm pit of the patient. This view helps you to assess the inferior and anterior wall of the Left Ventricle. The anterior wall of the left ventricle is seen on the right of the screen and inferior wall on the left of the screen. The severity of mitral valve lesions are better assessed in this view. 

Echocardiography Imaging Windows - The Apical 4 Chamber View

An Apical view  helps an echocardiographer to visualize all the 4 chambers  of the heart. For making this view the probe should be placed at the apex of the left ventricle. The marker or ridge of the probe is oriented towards the right shoulder blade of the patient. It is a good idea to abduct the patient`s left arm as it widens the intercostal spaces which as a result improves the view.

This view can help you to visualize  four chambers of the heart - (Left ventricle, left atrium, right ventricle and right atrium) and the  atrioventricular valves (Mitral and Tricuspid valves). The 4 chamber view also helps an echocardiographer to detect and grade tricuspid and mitral valve lesions, this can be easily done by using color flow imaging and doppler. One can also access size of the ventrilces, ejection fraction and pulmonary vein inflow for accesing diastolic function.






Some points to remember about apical 4 chamber view....

1. The right chambers are visualized on the left side of the screen and vice versa. 
2. The lateral wall of the left ventricle is on the right; the septal wall is in the center.
3. The size of the right ventricle should be about 2/3 of the Left ventricle. 
4. The function of the right ventricle can be evaluated by looking at the vertical motion of the lateral tricuspid annulus. The right ventricle usually contracts in the longitudinal manner.
5. Tricuspid valve is few millimeters towards the apex as compared to the Mitral valve. 

 

The Conduction System of the Heart

The conduction system of the heart is made up of specialized conducting tissue. Human heart works as an electrically timed pump. The electrical stimulation of the heart originates from SA node (Sinoatrial Node). The location of this node is in the right atrium near the opening of superior venacava. SA node is collection of specialized cells which are capable of producing automatic electrical activity. The SA node is also known as pacemaker of the heart.
The electrical stimulus generated by SA node in the right atrium travels to left atrium. The right and and left atrium  are activated in the first phase of electrical stimulation. As a result both of these chambers contract and pump the blood to right and left ventricle through Tricuspid and Mitral valve.
The electrical signal generated by SA node further travels to AV junction through specialized conducting tissue. The AV junction consists AV node, bundle of his and, right and left bundle branches. The bundle branches are located in the interventricular septum. The right and left bundle branches transmit the electrical stimulus to right and left ventricles respectively with the help of purkinje fibers. These specialized fibers are located in the ventricular myocardium.
Under normal circumstances the SA node serves as the primary pacemaker of the heart. But in some situations if SA node is unable to generate the impulses, the AV node acts as an escape pacemaker.

Heparin Induced Thrombocytopenia

HIT or Heparin induced thrombocytopenia is reported in patients who are under the treatment of UFH for 5 or more days. The patients suffering from this complication can develop arterial or venous thrombosis. That is why this subset of symptoms is also known as Heparin Induced Thrombocytopenia and thrombosis syndrome (HITTS). This complication of Heparin is a immune mediated syndrome. Heparin produce specific type of immunoglobulins which bridge the platelets. As a result this mechanism can cause both thrombocytopenia and thrombosis. In some patients the onset of HIT occurs after the discontinuation of the heparin therapy. This condition is known as delayed onset HIT.
Heparin therapy should be immediately stopped on the suspicion of HIT. Laboratory tests are available which can confirm the diagnosis of this complication. As HIT can also cause thrombosis so the patient needs an alternate form of anticoagulant therapy. Some drugs which are used for the therapy of HIT are lepirudin, argatroban and bivalirudin. Argatroban can be given to a patient suffering from HIT and needs PCI for ACS. Argatroban is a direct thrombin inhibitor. Argatroban can be given as a bolus of 240 -mcg/ kg bolus which is followed by 20-mcg/kg infusion per minute. This drug can be given even without GP IIb/IIIa blockade.

Heparin - The Acute Anticoagulant

Heparin which is also known as unfractioned Heparin is an Injectable anticoagulant work wonders in emergency situations like ACS and venous thrombosis. Heparin is a hetrogenous mucopolysaccharide. It mainly acts on the interaction of antithrombin and thrombin (factor lla). This drug inhibits the thrombin induced platelet aggregation. Heparin silmentaneously binds to thrombin and antithrombin. Heparin - Antithrombin complex also inhibits fator xa and xia and other factors which are part of intrinsic coagulation pathway. This drug mainly binds to proteins, macrophages as well as endothelial cells. This binding property of drug inactivates some part of drug. This anticoagulant can also induce thrombocytopenia in some cases. The dose of heparin needs to be controlled and monitored. Heparin is not excreted by kidneys so it can be easily prescribed to the patients suffering from renal diseases.

The Administration and Dose Control of intravenous Heparin


Heparin is usually diluted with normal saline or dextrose. As per European recommendations the heaparin should be given as a bolus of 60 - 70 IU/Kg , upto 5000 IU. The bolus should be followed by an infusion of 12-15 IU/ Kg (Maximum 1000 IU/Kg). The dose of the drug is adjusted with the help of aPTT levels. The aPTT value should be maintained 1.5 - 2.5 times the control aPTT value. The aPTT values can also be maintained from 50 to 75 seconds. The aPTT value should be monitored every 6 hrs. Higher aPTT values can result in cerebral bleeding. ACT or activated clotting time can also be used to control the dose of heparin in catherization laborateries and on the bed side.

Precautions should be taken to reduce the side effects and complications of the drug. The heparin infusion should not be continued more than 48 hours. Long duration infusions of heparin can result in HIT (Heparin Induced Thrombocytopenia). Patients suffering from hemophilia, SABE, GI tract ulcers and hepatic diseases are more prone to heparin induced bleeding disorders. Heparin can cause allergy in some patients because the drug is derived from animal tissue. In case of overdosage ,heparin should be stopped immediately and a slow infusion of 1% protamine sulfate should be started.

Echocardiography Imaging Windows - The Parasternal Window

There are four Types of windows which are used to visualize the heart from different planes and angles.

1. Parasternal
2. Apical
3. Suprasternal
4. Substernal

• Parasternal Window -

The Long Axis - The Parasternal long axis view is used to visualize Right Ventricle, Left atrium, Left Ventricle, intra ventricular septum, Inferior wall, Root of aorta, Aortic valve and the mitral valve. This view helps in estimating the size and contractility right and left ventricle. Echocardiographer can also see Chordae tendinae attached to AML and the papillary muscle of the left ventricle. Ejection fraction is calculated with the help of M mode cut at the chordal level.

The Short Axis- The parasternal short axis view is used to visualize the cardiac structures at four levels ....

• The level of great vessels
• Mitral Valve
• Papillary Muscles
• Apex

The structures which can be seen with through parasternal short axis view are Mitral Valve, Papillary muscles, Aortic Valve, Tricuspid Valve, Pulmonary artery, left atrium, right atrium, and right ventricle.