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University of Ottawa Heart Institute

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1 University of Ottawa Heart Institute
A Case Based Review of Cardiac Surgery Objectives for the MCC Qualifying Exam 2009 B-K Lam, MDCM University of Ottawa Heart Institute

2 Objectives Using demonstrative cases, this lecture will highlight the cardiac surgical aspects of the differential diagnoses included in the MCC qualifying exam objectives MCC Objectives for the Qualifying Examination covered in this review: Cardiac arrest (p. 13) Chest discomfort (p. 14) Dyspnea (p. 27) Acute (p. 27-1) Chronic (p. 27-2) Diastolic murmur (p. 62-1) Heart sounds pathological (p. 62-2) Systolic murmur (p. 62-3) Trauma Chest injuries – heart injury (p.109-4)

3 Case 1 A 48 year-old man is awakened early in the morning by sharp anterior chest pain that radiates to his back. He presents to the emergency room several hours later reporting that his pain has subsided but he is very short of breath. His past medical history is significant for poorly controlled hypertension. On examination, BP is 150/40, P100, RR 24, 88% on 2L/min of O2. His cardiac exam is noticeable for an absent S2, a loud 4/6 diastolic murmur; he also has an accompanying systolic ejection murmur. You also notice that his left carotid pulse is weaker than his right.

4 Case 1 - Questions What is the differential diagnosis?
Why is this patient short of breath? Why is his left carotid weak? What diagnostic tests would you order? In general, how do you classify this disorder? How would you classify it in this patient? What therapy would you implement in the emergency room? How would you further manage this patient and why?

5 “Top 3” DDx MI Aortic Dissection PE (Tension Pneumothorax)

6 Acute dyspnea - Ddx Cardiac Pulmonary
Ischemic heart disease (acute myocardial ischemia) Myocardial dysfunction (congestive heart failure) Ischemic/Hypertensive cardiomyopathy Dilated (idiopathic, alcoholic, hemochromatosis) Pericardial disease (tamponade) Valvular (Mitral regurgitation, Aortic Insufficiency) Pulmonary Upper airway Aspiration Anaphylaxis Ventilatory pump: Pleura (pneumothorax), Airways (bronchitis, bronchospasm) Gas exchanger Pulmonary embolus Pneumonia (viral, bacterial, atypical, fungus) ARDS Vasculitis (Wegener, Goodpasture) Respiratory control (metabolic acidosis, ASA toxicity)

7 Weak L carotid Dissection flap causing obstruction of true lumen

8 Diagnostic Tests CK, TNt ECG CXR TEE CT MRI

9 Classification Debakey Stanford B A

10 What type of dissection
Stanford A Debakey I or II

11 Acute Management Beta Blockade Antihypertensives
Reduces wall stress on aorta dP/dT Rupture prevention Antihypertensives Reduces shear stress on the aorta Anti-impulse/propagation therapy Nitroglycerine Nitroprusside

12 Definitive Therapy Surgery Type A dissection is a surgical emergency
Terrible natural history: “1%/hour” rule 50% dead in 48 hours 70% dead by 1 week Medical Tx = 60% mortality rate Modes of death Rupture with hemopericardium, hemomediastinum or hemothorax Organ dysfunction

13

14 Case 2 An 19 year old male is received a single stab wound to the chest outside a night club. He is brought to the ER, conscious and complaining of pain and shortness of breath. On examination, you observe a 3cm wound just left of his sternum in the 5th interspace. His BP is 85/60, P100, RR18, 95% on 2L/min of O2. His skin is slightly mottled and cool; his JVP is 8cm. By auscultation, air entry is fair bilaterally, heart sounds are muffled and peripheral pulses are weak. The rest of the physical is normal. Shortly after arriving in the patient becomes unresponsive. Pulses are not palpable, the monitor shows normal sinus rhythm.

15 Case 2 - Questions What are the most concerning clinical signs?
What is the diagnosis? What structure is most likely injured? What other structure should you be worried about? Prior to arrest what diagnostic tests would you order? What type of cardiac arrest is this and why has it occurred? How would you manage the arrest?

16 Concerning Clinical Signs
Hypotension Tachycardia Muffled heart sounds JVP elevated Weak peripheral Pulses CARDIAC TAMPONADE!

17 Commonly injured Right ventricular injury most common
Sits anteriorly in the mediastinum / LV posterior RV 43%, LV 34%, RA 16%, LA 7% Fatality rate 70-80% Survival probability depends on: Degree of anatomic injury Occurrence of cardiac standstill Beck triad only in 10-30% of tamponade cases Pericardiocentesis: 80% false negative FAST U/S: 95% sensitivity

18 Associated Chest Injuries
Cardiac Rule out LAD coronary artery injuries Valvular injury Lung (pneumo/hemothorax) Tracheobronchial 75-80% involvement of cervical trachea Esophagus (<1%) Diaphragm (45%) 15% >2cm, 13% missed with 85% returning with hernia) Thoracic great vessel (0.3-10%) 90% due penetrating trauma, 71% hospital survival

19 Diagnostic Tests Labs ECG CXR Echo FAST U/S

20 Cardiac Arrest PEA arrest
Cardiac tamponade prevents adequate cardiac filling and subsequently cardiac output This is not hypovolemia

21 Arrest Management ABC’s Intubation CPR Manage underlying cause
5H’s & 5T’s ER thoracotomy pericardiocentesis

22 Circulation 2005;112:IV-58-IV-66
Copyright ©2005 American Heart Association

23 Case 3 An unrestrained 23 year old driver ran a red light and collided with another vehicle in a t-bone fashion. He is brought to the ER, conscious complaining of sternal pain. On examination, you observe bruising on his anterior chest. HR 115, BP 90/50 and RR15. The patient’s JVP is flat and lungs are clear. A CXR is performed and it shows a widened mediastinum, a pleural cap and a fracture of the first rib.

24 Case 3 - Questions Explain the physical findings.
What is your differential diagnosis? What are the mechanisms of injury in blunt trauma? What tests would you order? What are the classic CXR findings for this condition? What is the usual anatomy and mechanism of this injury? (Where does it occur and why?) What is the initial management? What are the definitive management options?

25 Symptoms Hypotension Tachycardia Low filling pressures
Hypovolemic shock

26 Blunt thoracic trauma - Ddx
Aorta Traumatic aortic disruption Cardiac Contusion Rupture MI Pulmonary Pneumothorax Hemothorax Pulmonary contusion Tracheobronchial injury Rib fracture/flail chest Diaphragm rupture Esophageal rupture

27 Mechanisms of Injury Compression Fractured sternum
sternum and vertebrae Fractured sternum RV or aorta Torsion: attachment points Vena cavae to RA PV’s to LA Origin of arch vessels Aortic isthmus Rise in pressure Chambers or valves Pretre et al NEJM 97

28 Investigations CBC ECG CXR FAST U/S Echo/TEE CT Thorax (if stable)
Angiogram

29 CXR findings Wide mediastinum (supine CXR > 8 cm; upright CXR >6 cm) Obscured aortic knob; abnormal aortic contour Left "apical cap" (ie, pleural blood above apex of left lung) Large left hemothorax Deviation of nasogastric tube rightward Deviation of trachea rightward and/or right mainstem bronchus downward Wide left paravertebral stripe

30 Anatomy and Mechanism Aortic isthmus Deceleration Greatest shear force

31 Initial management Advanced Trauma Life Support® (ATLS®) ABCD
Secondary survey

32 Definitive Management
Stat surgical consult as poor natural history Conservative RX Open repair vs Stent graft

33 * Surgery VS Stenting Endovascular stent:
Location beyond subclavian artery Minimum of 5mm landing zone Diameter <36mm Absence of thrombus in fixation areas Non-tortuous Adequate access

34 Case 4 A surprisingly healthy and active 78 year old female presents to you with chest heaviness when she walks. On further questioning she admits to some dyspnea as well and she has been awakened from sleep with dyspnea several times recently. Her only past medical history is a hysterectomy. On physical examination, the BP is 100/80 and the pulse is 80 and regular but slow and delayed in quality. By auscultation, there is a 3/6 crescendo-decrescendo systolic ejection murmur at the right upper sternal border with radiation to the neck. There is no diastolic murmur noted. The rest of the physical exam is normal.

35 Case 4 - Questions What is your differential diagnosis?
What investigations would you order? In order of prevalence, what are the three most common causes of aortic stenosis? In this patient, how do you explain the angina? Name the two most commonly used types of valves in aortic valve replacement surgery? List the advantages and disadvantages of the valves you identified in the previous question? How is Coumadin monitored? What are the respective therapeutic ranges for a patient with an aortic and mitral prosthesis? What type of valve would you recommend for this woman?

36 Chronic Dyspnea - Ddx Aortic Stenosis Cardiac Valvular Ischemic
MS, AI, MR Ischemic CAD with SEM Cardiomyopathic Pulmonary Muscles/nerves/chest wall Lungs/Pleura Restrictive Airways obstructive Gas exchange

37 Investigations CBC CXR ECG Echo Angiogram

38 AS Etiology Acquired Congenital Rheumatic Degenerative/Age related
Bicuspid, unicuspid, quadracuspid Rheumatic

39 Angina in AS Supply Increased LVEDP therefore decreased diastolic coronary flow Decreased diastolic pressure Demand Hypertrophied Increased LVEDP

40 Valve types Mechanical Bioprosthetic

41 Pros & Cons Mechanical Bioprosthetic Pros: Cons: Pros: Cons:
Durability Large EOA Cons: Require anticoagulation Bioprosthetic Pros: Anticoagulation not required Cons: Limited durability Smaller EOA

42 Coumadin Monitoring: Theraputic Range: INR Mechanical Aortic 2.0-3.0
Mechanical Mitral


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