Clinical Notes: Sophie
Sophie, an eight year old neutered female Dachshund,
was bright and happy until three days ago.
Then she started vomiting. She now just lies there not wanting to move or eat.
Learning Objectives
- Identification of life-threatening abnormalities in a collapsed patient.
- Prioritising treatment of abnormalities detected.
- Arriving at an accurate diagnosis and formulating a long-term care and treatment
plan.
- Understanding the aetiology and management of pericardial effusion.
Clinical Condition
The pericardium is a fibrous sac that surrounds the heart. This sac is composed of two layers.
Between the two layers of the pericardium a few millilitres of fluid lie in the pericardial space.
This fluid serves to lubricate the movement of the heart within the pericardial sac.
This sac is attached to the great veins at the heart base.
Because of its fibrous nature the pericardium is not very distensible or accommodating of sudden changes of its volume.
This can be protective, for example in preventing acute distension of the myocardium.
However if there is a sudden change in the volume of fluid within the pericardium the inelastic nature of the pericardium can lead to sudden increases in pressure within the pericardial space and compression of the ventricles.
The majority of disease that we see associated with the pericardial sac results in accumulation of excessive fluid within the pericardial space.
Clinical signs observed reflect the effects that this has on the circulatory system.
The walls of the right side of the heart are much thinner than those of the left side.
This makes the right side more susceptible to compression as pressure within the pericardial sac increases. Compression of the right side of the heart will have significant effects of the hearts ability to relax and fill normally during diastole and signs of right sided heart failure will develop.
This compression of the heart is termed cardiac tamponade.
The amount of blood entering the pulmonary circulation from the right ventricle dictates the potential for filling the left side of the heart and thus cardiac output. Therefore, even though the left side of the heart is not directly compressed its output is compromised and there is a fall in systemic arterial blood pressure. In an attempt to restore cardiac output to normal the body responds by increasing the heart rate and retaining fluid at the kidneys. However this compensation is not enough and a reduction in tissue perfusion occurs.
This results in clinical signs of heart failure.
Case Management
Important points in management of collapsed patients
- Rapid assessment of the patient to identify which body system(s) are primarily
involved.
- Obtaining intravenous access.
- Characterising arrhythmias detected.
- Obtaining appropriate laboratory samples before initiating treatment.
Management of pericardial effusion
- Relieve cardiac tamponade to restore cardiac output
- Determine nature of effusion
- Carry out imaging studies to help determine the cause of the effusion
- Appropriate fluid therapy to maintain hydration without risking pulmonary hypertension due to volume overloading
Pericardiocentesis
bla bla bla
Suggested Management Plan for Sophie
- ABC - Airways, Breathing, Circulation. Identify any abnormalities involving
the cardiovascular or respiratory systems. These are the conditions that are
most likely to result in the death of your patient. Now consider how you might
identify the cause of the abnormalities detected (initially these were tachycardia
and poor peripheral perfusion).
- Either record an ECG or obtain a blood sample primarily for...
- The ECG in this case showed a very fast but regular rhythm. The complexes
appear normal in conformation. It is likely that this is a supraventricular
rhythm. Possible causes would include pain, hypercapnia, hypotension, reduced
myocardial contractility, reduced cardiac output secondary to poor cardiac
filling or poor oxygen delivery to the tissues secondary to anaemia.
- If not already obtained a blood sample should be collected. At this point
rapid assessment of PCV and total protein are useful to assess degree of anaemia or dehydration.
The measurement of BUN can indicate if acute renal failure has occurred secondary to the cardiac failure. A full haematology and biochemistry is useful, but
can wait.
- Imaging - Radiography and ultrasonagraphy have important roles in the diagnosis
of pericardial disease. Radiography:- the cardiac sillotte is usually enlarged
and rounded. In cases of acute onset pericardial effusion where the volume
of effusion is small this may not be readily appreciable. Echocardiography
will readily confirm the presence of a pericardial effusion. Where the patient
is suffering from tamponade this may be identified on echocardipgraphy as
collapse of the right atrium during dyastole. Careful searching may reveal
the presence of a mass within the pericardial space. These frequently involve
the right atrial appendiage or the heart base. The mass may be visable extending
through the pericardial sac or into adjacent cardiac chambers. The presence
of some fluid within the pericardial sac will make it easier to determine
the margins of a mass.
- Pericardiocentesis should be performed as outlined above. This will serve
to relieve the compressing on the right ide of the heart, improving cardiac
output and provide samples for analysis. Rapid draining of large volumes should
be avoided and patients should be closely monitored for signs of rapid re-effusion
as can occur especially where a haemorragic mass is the cause of the effusion.
In such cases a drain may need to be placed to allow repeated drainage without
the discomfort associated with repeated pericardiocentesis.
- Decision making. Once a diagnosis has been reached the findings have to
be discussed with the client. As veterinary surgeons our prime concern is
for the welfare of the patient. In this case the prognosis is hopeless. The
mass cannot be resected. The patient is clearly uncomfortable and the effusion
is recurring rapidly. The only realistic option for the management of this
case is euthansia. However immediate euthansia may not be possible if the
client cannot be contacted, or is unwillnig to give immediate permission without
'time to think' or consultation with other family members. It may be necessary
to administer fluid therapy, antiemetics, or repeatedly drain the pericardial
sac to keep the patient comfortable until the client is able to give permission
to euthanise.
Further Reading
- RVC Undergraduate Clinical Notes: Cardiology module.
- Small Animal Internal Medicine (Nelson and Cuoto) Page 185 onwards
- Manual of Veterinary Echocardiography (Boon) Page 355 onwards
- BSAVA Manual of Canine and Feline Emergency and Critical Care pages 48-50 and 326-327 (King and
Hammond) Page 178 onwards
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