Cardiothoracic Surgery Flashcards
Cardiac Risk Factors
Hypertension
Hypercholestermia
Diabetes
Smoking
Family hx
Rheumatic Fever
Peripheral Vacular Disease
Transient Ischemic Attacks/Stroke
Steps for placing a patient on CPB
Cardiopulmonary bypass (heart-lung machine)
● Patient administered heparin to prevent clotting
● Cannula inserted into right atrium/SVC and IVC to withdraw blood from the body
● Cannula is connected to tubing filled with isotonic crystalloid solution
● Venous blood removed is filtered, cooled/warmed, oxygenated and returned to the body via another cannula connected to the ascending aorta or femoral artery
● Patient administered cardioplegia (potassium-rich solution) either anterogradely into the aortic sinus or retrograde into coronary vein sinus
● At the end of the bypass, heparin is reversed with protamine
How is Myocardial protection achieved during cardiac surgeries?
Reducing the workload of the heart by off-loading the heart while on Cardiopulmonary bypass
Reducing the temperature of the heart by topical cooling
Arresting the heart (asystole) by using a high potassium solution called cardioplegia delivered in one of two ways:
- Antegrade (i.e. via a cannula in the aortic root which delivers cardioplegia into the coronary arteries)
- Retrograde (i.e. via a cannula in the coronary sinus which delivers cardioplegia into the cardiac veins)
These actions reduce the metabolic rate of the heart, reducing its oxygen demand and thus providing protection from ischaemia.
Workup prior to Cardiac Surgery
In addition to “routine bloods, chest x-ray, ECG”:
Complications of Cardiopulmonary Bypass
● Stroke (atheromatous emboli, hypoperfusion, air, microemboli), SIRS, renal and pulmonary dysfunction
● Bleeding: risk greater with prolonged bypass time, redo surgery for bleeding or tamponade or pre-op use of anticoagulants
● Death
What vessels are common used to achieve coronary artery bypass?
Left internal mammary artery (almost always used)
Long saphenous vein (examine for varicose veins)
Radial artery (perform Allen’s test).
What is a cardiopulmonary bypass machine?
What procedures require it?
● Any operation that involves stopping or opening the heart or great vessels requires CPB to maintain blood flow
● It is a technique that temporarily takes over the function of the heart and lungs during surgery, maintaining circulation and oxygen of the patient’s body
● It incorporates an extracorporeal circuit to provide physiological support
● The circuit includes pumps, cannulae, tubing, reservoir, oxygenator, heat exchanger and arterial line filter in addition to monitoring symptoms
What are the advantages of cardiopulmonary bypass?
● It has made increasingly complex cardiac surgeries possible, allows the heart to be a bloodless field
● It allows the heart to be arrested and prevents myocardial ischaemia
Infective Endocarditis Symptoms, Signs, Criteria
Symptoms: Fever/Chest Pain/Fatigue
Signs: Roths Spots/ Clubbing/ Osler’s Nodes/ Janeway Lesions
Most common valvular heart surgeries performed
Aortic valve replacement (most commonly for
aortic stenosis)
Mitral valve repair/replacement (most commonly for mitral regurgitation)
Symptoms of Valvular Insuficiency
Progressive Dyspnea on Excertion
Angina
Syncope
Symptoms of Left/Right Heart Failure
Definition of Severe Aortic Stenosis
Confirmed by ECHO:
■ Mean gradient >40mmHg
■ Aortic valve area <1cm2
■ Aortic jet velocity >4m/s
Valve Replacement Options
Classification System for Aortic Dissection
Stanford Classification
- Type A dissection: involves the aorta proximal to the left subclavian artery
- Type B dissection: involves the aorta distal to the left subclavian artery
De Bakey classification is less commonly used
Presentation of Acute Aortic Dissection
Severe, tearing chest/back/interscapular pain
Collapse/Shcol
Evidence of end-organ malperfusion due to abnormal blood flow through the false & true lumen => stroke, ischaemic limbs or ischaemic bowel
Diagnosis of Acute Aortic Dissection?
CT aorta with contrast
Fatal complications of Acute Aortic Dissection
Aortic ruptured
Cardiac tamponade
Myocardial infarction
Acute severe aortic incompetence
How is Repair of Acute Aortic Dissection Performed
During surgery, the patient is placed on CPB.
The segment of aorta with the intimal tear is resected and replaced with an interposition graft and blood flow is restored to the true lumen
Management of Acute Aortic Dissection
Target HR/BP
Emergency definitive treatment (surgery) is indicated for all Stanford type A aneurysms due to the risk of early complications (acute aortic regurgitation, myocardial infarction). Mortality in acute type A aneurism is 1-2% per hour, hence the need to quick intervention.
Patients with Stanford type B that are stable may be managed with medical treatment alone initially (beta-blockers, nitroprussimide). If the development of end-organ hypoperfusion, refractory pain, aneurysmal dilation or lesion progression is visible, surgical intervention becomes necessary. Patients with genetic conditions (e.g Marfan, Ehler Danlos) may benefit from early open intervention.
Causes of Pneumothorax
Management of Pneumothroax
Insertion of a pleural chest drain to remove the air from the pleural space.
Tension Pneumothorax
- Pathophysiology
- Signs/Symptoms
- Risks
- Management
Pathophysiology: pressure of the air in the pleural cavity increases and begins to compress the mediastinum (one- wave valve)
Signs/Symptoms:
- Dyspnea
- Chest Pain
- tachycardia
- hypotension
- reduced Sp02
- tracheal deviation (away from pneumothorax)
- reduced ipsilateral air entry
- hyper-resonant percussion
- engorged neck veins
Risks: As the intrathoracic pressure increases the mediastinum is forced to the contralateral side => kinking of the SVC and IVC resulting in dramatically reduced venous return and cardiac arrest.
Management: Insert a large-bore needle into the second intercostal space, mid-clavicular line. Later pleural chest drain should be placed
Insertion of Chest Drain
Borders of Triangle of Safety?
TNM Staging of Lung Cancer
How is operability for lung cancer determined?
Stage I / II non – small cell lung cancer, and in limited cases of stage III disease, is considered potentially curative with surgical resection. Essentially, this refers to patients with lung cancer that has limited nodal spread and no distant metastasis. The earlier the stage, the better the survival.
Options for resection of lung cancer
Complications of Lung Ressection
