Presentation on theme: "University of Ottawa Heart Institute"— Presentation transcript:
1 University of Ottawa Heart Institute A Case Based Review of Cardiac Surgery Objectives for the MCC Qualifying Exam 2009B-K Lam, MDCMUniversity of Ottawa Heart Institute
2 ObjectivesUsing demonstrative cases, this lecture will highlight the cardiac surgical aspects of the differential diagnoses included in the MCC qualifying exam objectivesMCC 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)TraumaChest injuries – heart injury (p.109-4)
3 Case 1A 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?
10 What type of dissection Stanford ADebakey I or II
11 Acute Management Beta Blockade Antihypertensives Reduces wall stress on aortadP/dTRupture preventionAntihypertensivesReduces shear stress on the aortaAnti-impulse/propagation therapyNitroglycerineNitroprusside
12 Definitive Therapy Surgery Type A dissection is a surgical emergency Terrible natural history:“1%/hour” rule50% dead in 48 hours70% dead by 1 weekMedical Tx = 60% mortality rateModes of deathRupture with hemopericardium, hemomediastinum or hemothoraxOrgan dysfunction
14 Case 2An 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?
17 Commonly injured Right ventricular injury most common Sits anteriorly in the mediastinum / LV posteriorRV 43%, LV 34%, RA 16%, LA 7%Fatality rate 70-80%Survival probability depends on:Degree of anatomic injuryOccurrence of cardiac standstillBeck triad only in 10-30% of tamponade casesPericardiocentesis: 80% false negativeFAST U/S: 95% sensitivity
18 Associated Chest Injuries CardiacRule out LAD coronary artery injuriesValvular injuryLung (pneumo/hemothorax)Tracheobronchial75-80% involvement of cervical tracheaEsophagus (<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
23 Case 3An 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?
27 Mechanisms of Injury Compression Fractured sternum sternum and vertebraeFractured sternumRV or aortaTorsion: attachment pointsVena cavae to RAPV’s to LAOrigin of arch vesselsAortic isthmusRise in pressureChambers or valvesPretre et al NEJM 97
32 Definitive Management Stat surgical consult as poor natural historyConservative RXOpen repair vs Stent graft
33 * Surgery VS Stenting Endovascular stent: Location beyond subclavian arteryMinimum of 5mm landing zoneDiameter <36mmAbsence of thrombus in fixation areasNon-tortuousAdequate access
34 Case 4A 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?