Cardiac Surgery - Surgery

Question 1

Types of Cardiac operations (B)

Answer 1

1- Extracardiac Operations:
-Operations carried out on the main vessels outside the heart or the pericardium. Surgery is usually performed without cardiopulmonary bypass.
-Examples include pericardiectomy, ligation of patent ductus arteriosus, repair of aortic coarctation and palliative procedures for congenital heart diseases.
2- Closed Cardiac Operations:
-Blind procedures performed by the finger of the surgeon or by an instrument placed inside the heart, e.g. closed mitral valvotomy for mitral stenosis. These operations are rarely done
-In current era, and have replaced with open heart surgery techniques or endovascular catheter-based procedures.
3-Open Heart Surgery:
During these operations the heart must be functionally disconnected from the circulations, and an artificial heart lung machine (cardiopulmonary bypass, extracorporeal circulation) do the function of the heart and the lung temporarily. The operations performed under direct vision in a bloodless field within the chambers of the heart or great vessels. Median sternotomy is the classic approach for open heart surgery that provides an excellent exposure.

Question 2

Cardiopulmonary Bypass short note (A)

Answer 2

-CPB is a technique used to temporarily divert the blood from the heart and lungs and provides oxygenation and pump functions in the presence of a still bloodless heart using a heart-lung machine.
-CPB is commonly used in heart surgery requiring opening chambers of the heart as congenital defect reconstruction and valve replacement or repair and in operations requiring arrested heart as in coronary artery bypass grafting to support the circulation during that period.

As any extracorporeal circulation CPB needs:
1) Heparinization using heparin in a dose of 300 U/kg. After weaning from CPB and removal of cannulae, heparin is reversed by protamine sulfate.
2) Using priming fluids to augment peripheral circulation and to decrease blood viscosity

Cannulation
1) Arterial Cannulation: cannula is inserted usually in Aorta (some cases in femoral artery)
2) Venous Cannulation for SVC and IVC (sometimes single cannulation in R.A)

Myocardial protection
By injecting cardioplegic solution after aortic cross–clamping either in proximal Aorta (antegrade), or in coronary sinus (retrograde).

Minimal invasive cardiac Surgery: Median sternotomy is the standard approach for open heart surgery, but, also other approaches can be used as right submammary thoracotomy for ASD closure and mitral valve surgery. The main drawback of this incision is the small field it yield, with difficult management in emergency situations Recently, Video-assisted thoracoscopic surgery (VATS) was introduced for open heart surgery.

Question 3

Mitral stenosis (Indications and options for management) (A++)

Answer 3

Indications for intervention:
* Symptomatic patients (decreased exercise tolerance, exertional dyspnea) with severe mitral stenosis with mitral valve area ≤1.5 cm2 (normally 4-6 cm2).
* Asymptomatic patients with severe mitral stenosis (mitral valve area ≤1.5 cm2), severe left atrium enlargement and elevated pulmonary artery systolic pressure (PASP) >50 mmHg.

Options for management:
 Percutaneous balloon mitral valvuloplasty:
* Needs good leaflet pliability, minimal chordal thickening and intact subvalvular mechanism.
* Contraindicated if left atrial thrombus present.
* Contraindicated with concomitant mitral regurgitation over mild degree.
 Open mitral commissurotomy
* For patients with mild calcification and mild leaflet/chordal thickening.
 Mitral valve replacement
* For moderate to severe calcification with severely fibrosed valve leaflets or subvalvular apparatus.
* Most patients with rheumatic etiology require mitral valve replacement.

Question 4

Mitral regurgitation ( Indications and Surgical options) (A++)

Answer 4

Indications for surgery:
* Symptomatic patients with chronic severe MR.
* Asymptomatic patients with chronic severe MR and LV dysfunction (LVEF 30 to 60% and/or LVESD ≥40 mm), with onset of atrial fibrillation, or pulmonary hypertension ((PA systolic pressure > 50 mmHg).
* Acute MR associated with CHF, cardiogenic shock, or papillary muscle rupture

Surgical Options:
 Mitral Valve Repair:
* Myxomatous degeneration of the MV is ideal for repair.
* Ischemic mitral regurge
* Selected cases of rheumatic etiology.
 Mitral valve replacement:
* Indicated when satisfactory repair cannot be accomplished.
* Replacement usually required if heavily calcified annulus or if papillary muscle rupture.
* Patients with MR due to rheumatic heart disease are more likely to need MV replacement.

The advantages of valve repair versus replacement are lack of need for chronic anticoagulation, elimination of prosthesis-related complications, and the low rate of endocarditis.

Question 5

Aortic stenosis (Indications and surgical options) (A++)

Answer 5

Indications for surgery
* Symptomatic patients (dyspnea on exertion, syncope, and exertional angina) with severe AS [mean valve gradient over 40 mmHg or valve area less than 1.0 cm2 (normal 3-4 cm2)].
* Asymptomatic patients with severe AS and Left Ventricular dysfunction (LVEF <50 %), decreased exercise tolerance or fall in systemic blood pressure withexercise.

The options for management are surgical aortic valve replacement. Transcatheter aortic valve implantation (TAVI) can be considered for high surgical risk patients.

Question 6

Aortic regurgitation (Indication and surgical options) (A++)

Answer 6

Indications for surgery
* Symptomatic patients with severe AR regardless of LV systolic function
* Asymptomatic patients with severe AR and Left Ventricular dysfunction (LVEF <50 %).

Most patients with aortic valve regurgitation indicated for surgery require aortic valve replacement. Aortic valve repair had a limited role in aortic valve surgery (in selected cases).

Question 7

Mechanical VS Bioprosthetic Valves (A++)

Answer 7

Long durability (VS) Short durability

Long-term anticoagulation with warfarine. Target INR: 2.5-3.5 (VS) Usually long-term anticoagulation not needed.

Increased risk of thromboembolism (1-3%/year). (VS) Low risk of thromboembolism

Increased risk of hemorrhage: 1-2%/year (VS) Low risk of hemorrhage

Question 8

Palliative procedures and indications (A)

Answer 8

A.Pulmonary artery banding
-A pulmonary artery band reduces pulmonary blood flow and pressure protecting the pulmonary vasculature, aiming to avoid progression to irreversible pulmonary vascular disease.
- Indications:
a- Complex disease e.g. univentricular heart when palliation is necessary.
b- Multiple VSD’s when surgery is better deferred to childhood.
c- To prepare and retrain the left ventricle in patients with transposition of the great arteries for future arterial switch procedure

B. Aortopulmonary shunt:
- Aiming to increase pulmonary blood flow
- Indications: In summary, aortopulmonary shunts will benefit any patient with pulmonary obstruction. The ideal example is pulmonary atresia with or without VSD.

Question 9

Complete repair in cardiac surgery (A)

Answer 9

-Complete repair is feasible in many extra cardiac as well as intra cardiac congenital anomalies

A-Repair of extra cardiac anomalies: usually no need for cardiopulmonary bypass
The commonest examples are patent ductus arteriosus (PDA), and coarctation of aorta.
-PDA is approached through a limited left posterolateral thoracotomy, and is usually divided between clamps or ligated
- Coarctation of aorta is approached through a left posterolateral thoracotomy.
Surgical treatment is preferred than balloon dilatation. Resection of the coarcted segment and end –to- end anastomosis is the best technique. Also, dilatation of the coarcted segment with subclavian flap, or synthetic polytetrafluoroethylene (GORE-TEX) patch can be used.

B- Repair of intra cardiac anomalies: Usually carried out using cardiopulmonary bypass.
- The commonest anomalies are ventricular septal defects (VSD), atrial septal defects (ASD), and tetralogy of Fallot.
- Tetralogy of Fallot: Accounts for 15% of all cyanotic heart diseases. Characterized by
i) a large ventricular septal defect(VSD),
ii) the aorta straddling the defect and overriding both ventricles,
iii) RV outflow tract obstruction(RVOTO), and
iv) RV hypertrophy.
The repair consists of closure of VSD with a patch (usually synthetic Dacron or GORE-TEX patch) and relief of the obstruction of the RV outflow tract and the stenosed pulmonary tract. The operation is carried out using cardiopulmonary bypass.
The results of surgery show dramatic improvement in patient’s tolerance to exercise and disappearance of cyanosis.
- Atrial and ventricular septal defects (ASD and VSD): ASD is usually closed using pericardial patch and VSD is usually closed using Dacron or GORE-TEX patch. The operation is carried out using cardiopulmonary bypass.

C: Coronary Artery Bypass Graft (CABG) Surgery

Question 10

Anatomic considerations in CABG (B)

Answer 10

From surgical point of view, coronary system is divided into 4 parts: Left main coronary artery, left anterior descending artery (and its diagonal branches), left circumflex artery (and its marginal branches), and right coronary artery (and its posterior descending branch).

A significant lesion affecting the left main coronary artery is called left main disease, and this lesion affects blood flow to both left anterior descending artery and left circumflex artery.

A significant lesion (or lesions) affecting one of the other three arteries or one of its large branches is considered one-vessel disease , while significant lesions affecting two arteries or three arteries are considered two vessel disease and three-vessel disease respectively.

Question 11

Indications of CABG (A++)

Answer 11

• Left main coronary artery: stenosis more than 50% (annual mortality 10-15% if untreated).
• Left main equivalent: more than 70% stenosis of proximal left anterior descending (LAD) and proximal circumflex artery (PCA)
• Three vessel disease , particularly in diabetics
• one or two vessel disease with extensive myocardium at risk, not PTCA candidate
• Coronary occlusive complications during PTCA or other endovascular interventions
• Surgery for life-threatening complications after acute MI; including VSD, ventricular free-wall rupture or acute MR

Question 12

Techniques of CABG (B)

Answer 12

The standard approach for CABG is midline sternotomy
-There are 2 different techniques for doing CABG: the traditional, and the commonly used one, is the on-pump CABG, using cardiopulmonary bypass and with arrested heart and the other technique, the off-pump coronary artery bypass (OPCAB) with a beating heart and without the use of cardiopulmonary bypass.

• On-pump CABG performed with very low mortality and morbidity and with excellent results. It is still the most widely used technique worldwide. Off-pump CABG (OPCAB) is a technique with theoretical benefit of lower complication rates. But, recent studies reported higher rates of incomplete revascularization, decreased midterm survival and more need for revascularization for off-pump CABG patients as compared to on- pump CABG patients

Question 13

Conduits for CABG (A++)

Answer 13

*Left internal thoracic (mammary) artery (LITA, LIMA)
* LIMA to LAD is the gold-standard; with excellent long term patency (90-95% at 15 years).
* Should always be used unless:
1) Emergency operation with hemodynamic decompensation,
2) History of chest wall radiation or radical mastectomy,
3)Proximal left subclavian artery stenosis,
4) Iatrogenic injury or hematoma during harvesting, and
5) Insufficient flow due to small size or persistent spasm

*Reversed saphenous vein grafts (SVG)
* Commonly used especially when many grafts such as triple or quadruple bypass are required
* Ten-year patency is 60-70%. The causes of graft failure are thrombosis, intimal hyperplasia, and graft atherosclerosis.

• Right internal thoracic (mammary) artery (RITA, RIMA)
• Used in bilateral internal thoracic (mammary) artery grafting
• Patients receiving bilateral IMAs have less risk of recurrent angina, but with the possibility of higher rates of sternal infection, dehiscence and mediastinitis in elderly, obese or diabetic patients.
• Radial artery
• Approximately 85-90% patency at 5 years
• Recent studies support the use of radial artery as a second option after LIMA as a conduit for CABG.

Question 14

Types of thoracic trauma (A)

Answer 14

Thoracic trauma is broadly categorized by mechanism into blunt or penetrating trauma.
The most common cause of blunt chest trauma is motor vehicle collisions (MVC) which account for up to 80% of injuries. Other causes include falls, vehicles striking pedestrians, acts of violence, and blast injuries. The majority of penetrating trauma is due to gunshots and stabbings.
Blunt chest trauma is more common than penetrating trauma and directly comprises 20 to 25% of trauma deaths. Penetrating chest trauma is associated with higher overall mortality.

Question 15

Thoracic trauma classification (A)

Answer 15

1-Chest Wall Injuries
Rib fractures account for the majority of thoracic injuries and are found in around 50% of patients with blunt chest trauma. Sternal fractures are seen in about 5% of patients with chest trauma. Sternoclavicular dislocations

2-Injuries of the Intrathoracic Organs
A)Pleural Injuries:
● Pneumothorax
● Haemothorax
● Chylothorax
● Pleural collection related to GIT rupture (Esophageal rupture).
B) Diaphragm Injuries:
A diaphragmatic rupture can be caused by blunt or penetrating injuries. It occurs in 0.2–5% of patients with blunt chest trauma. Ruptures on the left side are three to four times more common than lesions on the right side.
C) Lung Injuries:
Parenchymal lung injuries appear as pulmonary contusions and lacerations.
D) Injuries to the Mediastinum:
A pneumomediastinum (mediastinal emphysema) may occur after pharyngeal, tracheobronchial, or esophageal lesions after either penetrating or blunt trauma. Pericardial injuries (e.g., cardiac injury and vascular ruptures) can result in pneumopericardium and/or hemopericardium into the pericardial cavity. A hemopericardium may be complicated by the development of pericardial tamponade with subsequent hemodynamic instability.

Question 16

Clinical picture of thoracic trauma patient (A)

Answer 16

• Symptoms include pain, which usually worsens with breathing if the chest wall is injured, and sometimes shortness of breath.
• Common findings include chest tenderness, ecchymoses, and respiratory distress; hypotension or shock may be present.
• Neck vein distention can occur in tension pneumothorax or cardiac tamponade if patients have sufficient intravascular volume.
• Decreased breath sounds can result from pneumothorax or hemothorax; percussion over the affected areas is dull with hemothorax and hyperresonant with pneumothorax.
• The trachea can deviate away from the side of a tension pneumothorax.
• In flail chest, a segment of the chest wall moves paradoxically—that is, in the opposite direction from the rest of the chest wall (outward during expiration and inward during inspiration); the flail segment is often palpable.
• Subcutaneous emphysema causes a crackling or crunch when palpated. Most often, pneumothorax is the cause; when extensive, injury to the tracheobronchial tree or upper airway should be considered.

Question 17

Definition of flail chest (A)

Answer 17

Flail chest is a traumatic condition of the thorax that is usually associated with significant blunt chest wall trauma. It may occur when 3 or more ribs are broken in at least 2 places.

A flail chest arises when these injuries cause a segment of the chest wall to move independently of the rest of the chest wall. This can create a significant disturbance to respiratory physiology.

Question 18

Diagnosis of flail chest (A)

Answer 18

• It is considered a clinical diagnosis as everybody with this fracture pattern does not develop a flail chest.
• It may be suspected based on radiographic findings but is diagnosed clinically.
• The chest x-ray may be the first study that helps specifically with the flail chest. The test of choice for evaluating not only the flail chest but also for associated injury is the CT chest scan.

Question 19

treatment of flail chest (A)

Answer 19

• Management of a flail chest should include these areas of concern: maintaining adequate ventilation, fluid management, early aggressive pain management, excellent pulmonary toilet and management of the unstable chest wall.
• Ventilation should be maintained with oxygen and non-invasive ventilation when possible.
• Internal pneumatic stabilization has been used successfully to treat complicated cases. Surgical stabilization may be considered in patients who are getting a thoracotomy for other reasons, in those who fail to wean off a ventilator, and in those whose respiratory status continues to decline despite other treatments.

Question 20

Definition of pneumothorax (A)

Answer 20

• Pneumothorax is the accumulation of air between the parietal and visceral pleura inside the chest.
• Tension pneumothorax is a severe condition that results when air is trapped in the pleural space under positive pressure, displacing mediastinal structures and compromising cardiopulmonary function.
• This occurs when injured tissues forms a one-way valve allowing air to enter the the pleural space and preventing it from escaping naturally.

Question 21

Diagnosis of pneumothorax (A)

Answer 21

• Clinical picture: tension pneumothorax should be suspected in individuals with respiratory distress, tracheal deviation, distended neck veins, low blood pressure.
• Clinical examination: Bulge of the affected side, decreased or absent breath sounds upon lung auscultation, hyper-resonance on percussion.
• Radiological: Chest x-ray showing jet black opacity of the affected side of the thorax, shift of the mediastinal structures to the opposite side and flattening of the diaphragm. In some cases, a computerized tomography (CT) scan may be needed to provide more-detailed images. Ultrasound imaging also may be used to identify a pneumothorax.

Question 22

treatment of pneumothorax (A)

Answer 22

If the patient is hemodynamically unstable and clinical suspicion is high for tension pneumothorax, immediate needle decompression must be performed without delay.

• Needle decompression is done at the second intercostal space in the midclavicular line above the rib using a large bore intravenous catheter.
• Following needle decompression, a CXR is done, and a chest tube is usually placed in the 5th intercostal space at the anterior axillary line.

Question 23

Hemothorax definition (A)

Answer 23

It is a collection of blood in the pleural space, a potential space between the visceral and parietal pleura. It may be mild, moderate or massive amount. Bleeding may arise from the chest wall, intercostal or internal mammary arteries, great vessels, mediastinum, myocardium, lung parenchyma, diaphragm, or abdomen.

Question 24

Diagnosis of Hemothorax (A)

Answer 24

Clinical picture: evidence of blunt or penetrating thoracic trauma. Patient may show dyspnea, pallor, hypotension or tachypnea.

Clinical examination: Diminished air entry on the affected side, dullness on percussion.

Radiological diagnosis: chest X-ray shows pleural collection obliterating the costophrenic angle with upper border rising to axilla. Shift of the mediastinum to the opposite side can be detected in massive collection. CT scan is accurate method for diagnosis of intrthoracic lesions. Ultrasound shows homogenously echogenic effusion.

Question 25

Treatment of hemothorax (A)

Answer 25

Treatment:
The initial treatment of hemothorax is tube thoracostomy.
A large bore chest tube (36 Fr
or larger) should be placed to ensure effective evacuation on intrapleural blood and re-expansion of the lung.
If the hemothorax is massive and the bleeding is ongoing, the patient should be explored through thoracotomy approach.

Question 26

Cardiac tamponade definition (A)

Answer 26

Cardiac tamponade is a medical or traumatic emergency that takes place when abnormal amounts of fluid accumulate in the pericardial sac compressing the heart and leading to a decrease in cardiac output and shock.

Question 27

Diagnosis of Cardiac tamponade (A)

Answer 27

The diagnosis of cardiac tamponade is a clinical diagnosis that requires prompt recognition and treatment to prevent cardiovascular collapse and cardiac arrest.

The classic physical findings in cardiac tamponade included in Beck’s triad are hypotension, jugular venous distension, and muffled heart sounds

Radiological diagnosis: Echocardiography is the best imaging modality to confirm presence of pericardial effusion, its size, and whether it is causing compromise of cardiac function (right ventricular diastolic collapse, right atrial systolic collapse, plethoric IVC). A chest x-ray may show an enlarged heart shadow. CT chest can also pick up pericardial effusion

Question 28

Treatment of cardiac tamponade (A)

Answer 28

The treatment of cardiac tamponade is the evacuation of pericardial fluid to help relieve the pressure surrounding the heart. This can be done by performing echo- guided needle pericardiocentesis at the bedside in a sub-xiphoid window.

Surgical options include subxiphoid pericardial tube and creating a pericardial window.

Emergency department resuscitative thoracotomy and the opening of the pericardial sac is a therapy that can be used in traumatic arrests with suspected or confirmed cardiac tamponade.

Question 29

Definition of hemoptysis (A)

Answer 29

Massive hemoptysis is a term used to describe a large amount of expectorated blood or rapid rate of bleeding that is associated with a serious risk of mortality.

Question 30

Causes of hemoptysis (B)

Answer 30

Bronchiectasis, TB, mycetomas, necrotizing pneumonia, cryptogenic hemoptysis and bronchogenic carcinomas are considered among the most common causes of massive hemoptysis. Coagulopathy and platelet disordes, foreign body aspiration, bronchoscopic tissue biopsy and iatrogenic are less common causes.

Question 31

TTT of hemoptysis (A)

Answer 31

1-The initial step in the management of massive hemoptysis should focus on efficient stabilization.
2-Advanced cardiac life support (ACLS) should be implemented as soon as possible. The non-bleeding lung should be protected, and this may be achieved by turning the patient to the bleeding side, such that the blood is isolated to the bleeding lung due to gravity, and the non-bleeding side remains intact and fully aerated
3-Establishing a definitive airway is the most important step in the management of massive hemoptysis.
4-Bronchoscope: the two key objectives of bronchoscopic management of hemoptysis are: (1) clearing the airway of blood to maintain adequate ventilation; and (2) establishing a clear vision of the bleeding side to enable implementation of bronchial blocker or other endobronchial techniques. Instillation and irrigation using ice cold saline through bronchoscope can help to control bleeding. Epinephrine and norepinephrine have been used in cases of massive hemoptysis.
5-Bronchial blocking to prevent the aspiration and allow time for management using catheters for balloon tamponade.
6-Endobronchial ablation, requires skills and expertise as well as equipment.
7-Endovascular embolization.
8-Surgical exploration.

Question 32

Indications of Thoracotomy incision (A++)

Answer 32

1-Penetrating thoracic injury with cardiac arrest.
2-Immediate output of >1500 cc of blood from the chest tube insertion.
3-Ongoing blood loss (>200-300 cc) of blood per hour over 4 successive hours.
4-persistent haemothorax despite adequate chest tube placement.
5-Ongoing massive air leak.
6-Evidence of cardiac tamponade.
7-Evidence of oesophageal injury.
8-Evidence of diaphragmatic injury.
9-Large chest wall defect requiring reconstruction.

Question 33

Intercoastal chest tube (Function, site and indications) (A++)

Answer 33

Function of ICT:
It creates negative pressure in the chest cavity and allows re-expansion of the lung. It helps remove air (pneumothorax), blood (hemothorax), fluid (pleural effusion or hydrothorax), chyle (chylothorax), or purulence (empyema) from the intrathoracic space.

Site of insertion:
ICT is commonly inserted in the 5th intercostal space in the anterior axillary line of the affected side.

Indications of insertion:
o Unresolved primary pneumothorax greater than 2 cm.
o Secondary pneumothorax greater than 2 cm.
o Unilateral pleural effusion causing breathlessness – insert drain to relieve symptoms and aid diagnosis.
o Empyema.
o Chylothorax.
o Pleural collection related to GIT rupture.
o Bilateral pleural effusions if decompensated despite optimal medical management.
o Tension pneumothorax after needle decompression.
o Palliation of breathlessness in malignant pleural effusions and to facilitate pleurodesis.
o Post-surgical.