Cardiac - AAA, AD, DVT and PE Flashcards
Aortic dissection
Most common location of dissection
Classification systems
Use of classification
Ascending aorta dissection 2x more common than descending aorta
Right lateral wall of ascending aorta is most common site of aorta dissecction
DeBakey classification
- Type 1: involves ascending aorta, aortic arch, descending thoracic aorta
- Type 2: involves ascending aorta only
- Type 3a: involves descending aorta distal to left subclavian artery and proximal to celiac artery
- Type 3b: involves thoracic and abdominal aorta distal to left subclavian artery
Stanford classification Type A: (60%)
- involves ascending aorta, may progress to aortic arch and abdominal aorta
- Life threatening, requires emergency surgical repair
Stanford classification type B:
- involves descending thoracic and abdominal aorta
- Usually managed medically unless dissection into end-organ vessels leading to ischemia, or concomitant aortic aneurysm with high risk of rupture
Acute aortic syndromes
Definition
Types/ variants
Definition:
- spectrum of life-threatening aortic conditions
Includes aortic dissection, intramural haematoma, penetrating aortic ulcers, intimal tear without haematoma, periaortic haematoma
Aortic intramural haematoma:
- 5-20% of acute aortic syndrome
- Focal haematoma confined between intima and media layer due to spontaneous rupture of vasa vasorum without detectable intimal tear or dissection flap due to hypertension, trauma or iatrogenic injury
- ascending type managed surgically
- descending type managed medically unless >1cm thick, aorta diameter >4cm or progression on serial imaging
Penetrating aortic ulcer:
- Aortic ulcer penetrating adventitia with subadventitial haematoma
- lead to aortic dissection or perforation
Limited intimal tear without haematoma:
- stellate or linear intimal tear with exposure of underlying aortic media or adventitia
Aortic dissection
Risk factors
Pathophysiology
Risk factors:
- Hypertension
- Collagen disorders: Marfan syndrome, Ehlers-Danlos syndrome
- Aortic aneurysm
- Bicuspid aortic valve
- Family history of aortic dissection
Pathogenesis:
- Tear in aortic intima
- Blood flow into aortic media and creates false lumen by separating intima layer
- False lumen dilatation depends on BP, size of entry tear, depth of dissection plane within media and percentage of aortic circumference involved
- True lumen may collapse due to pressure differential, exacerbated by muscular elements within dissection flap
Aortic Dissection
S/S
S/S
Acute pain:
-Site: Anterior for type A, Back/ abdomen for type B
- Onset: abrupt
- Character: Sharp, tearing, knife-penetrating
- Radiation: generalized in thorax or abdomen
Pulse deficit:
- Weak of absent peripheral pulses due to impaired flow
BP:
- Hypertension: Type A 35%, Type B 70%
- Hypotesion: Type A 25%, Type B 5%
- Hypotension due to Aortic regurgitation, Cardiac tamponade, Acute MI, Haemothorax, Haemoperitoneum
Aortic regurgitation: Early diastolic decrescendo murmur with wide pulse pressure
Focal neurological deficits
o Paraplegia (spinal cord)
o Altered level of consciousness (carotid artery)
o Horner’s syndrome (superior cervical ganglion)
o Hoarseness (left recurrent laryngeal nerve
Aortic dissection
Investigations
D/dx
Differential diagnosis
Pneumothorax
Pulmonary embolism
Pericarditis
Acute pancreatitis
Acute myocardial infarction (AMI)
Investigations:
Biochemical: Cardiac enzymes: cTnT, cTnI, CK-MB
Radiological:
Chest X-ray (CXR) features: differentiate from pneumothorax
o Irregular or wavy aortic outline
o Widening of aortic silhouette
o Widening of mediastinum (erect PA = 6 cm and supine AP = 8 cm) (unable to see the aortic knuckle and descending aorta)
ECG: Differentiate from AMI
ECHO: for AR, pericardial effusion, dissection flap
CT angiography/ Contrast CT Aortogram (stable): compressed true lumen, identify false lumen
Transesophageal echocardiography (TEE) (unstable): AR. pericardial effusion, dissection flap, ture and false lumens
Aortic dissection
Management options
General care:
- ICU or coronary care unit CCU admission, complete bed rest
- NPO with IV saline, morphine analgesics
Medical: Uncomplicated type B patients: medical therapy + long term antihypertensives
- Sodium nitroprusside (give second): vasodilator to control systolic BP to 100-120mmHg
- Labetalol (give first): B-blocker to control HR at 60/min
Surgical:
- All type A patients
- Complicated type B patients (end-organ hypoperfusion)
Surgical treatment options:
- Open dissection repair: excision of intimal tear, obliteration of entry into false lumen, reconsitution of aorta by synthetic vacular graft, repair/ replace AV
- Endovascular repair: endovascular stent grafting
Aortic dissection
Complications
Prognosis
Type A
* Dissection in aortic valvular annulus - Aortic regurgitation
* Dissection into pericardium - Cardiac tamponade
* Dissection in coronary artery ostia - Myocardial infarction
* Focal neurological deficits related to cerebrovascular ischemia
Type B
* Dissection into abdominal aortic branches Celiac/ Renal/ LL ischemia
* Focal neurological deficits related to spinal ischemia
Mortality of Type B dissections
* 10% at 30 days
* 25% at 3 years
* 50% at 5 years
AAA
Risk factors
↑ Risk of AAA
Elderly + Caucasian + Male
Smoking
Atherosclerosis
Hypertension
Family history of AAA
Presence of large artery aneurysm
* Iliac artery aneurysm
* Femoral aneurysm
* Popliteal aneurysm
↓ Risk of AAA
Non-Caucasian females
Diabetes
AAA
Investigations
CBC with differentials
* Anemia: Hypochromic microcytic anemia due to acute blood loss
* Leukocytosis: Infected or inflamed aneurysm
Clotting profile: Disseminated intravascular coagulopathy (DIC)
o ↑ (Prolongation) of PT, APTT, TT
o ↓ Coagulation inhibitor (e.g. anti-thrombin)
o ↓ Platelet count
o ↓ Fibrinogen level from consumption of coagulation factors and platelets
o ↑ Fibrin degradation products especially D-Dimers (Clot lysis indicator)
Inflammatory markers: ↑ ESR and CRP
o Infected or inflamed aneurysm
Arterial blood gas (ABG): Metabolic acidosis
o Acute blood loss leading to shock
Imaging:
- USG abdomen/ Focused Assessment with Sonography in Trauma (FAST) exam
- CT angiography (CTA): for urgent surgical planning for symptomatic patients
- MR angiography (MRA): for contrast contraindications
AAA
Treatment options
Indication for surgery
Non-operative management
Monitoring with USG/ CTA yearly
Lifestyle modification
o Smoking cessation
o Control of hypertension
o Exercise
o Treatment of COPD
Indications for surgery of uncomplicated AAA
* Symptomatic aneurysm of any size
* ALL AAA > 5 cm (5.5 cm in Caucasians) unless patient is medically unfit or limited life expectancy
* Rapidly expanding AAA > 1.0 cm/ year or > 0.5 cm/ 6 months
* Saccular aneurysm
Surgical options:
* Open surgical repair
* Endovascular aneurysm repair (EVAR)
Ruptured AAA:
- IV fluid resuscitation (crystalloids/ colloids/ blood) to maintain organ perfusion
- Allows permissive hypotension (SBP < 100 mmHg). avoid over-resuscitation causing dilution of clotting factor and thrombus destabilization
- Emergency EVAR repair
Open surgical AAA repair
Procedure
Approaches
Replacement of diseased aortic segment with a tube or bifurcated prosthetic graft
Transabdominal or retroperitoneal approach
Transabdominal: Midline abdominal incision
Retroperitoneal: Left retroperitoneal incision
- Advantageous in patients with previous intraabdominal surgery, obese patients,
COPD patients
- Proximal suprarenal or supraceliac control of aorta is more easily achieved by retroperitoneal approach
Open surgical AAA repair
Complications
CVS: Arrhythmia/ AMI
Vascular: Intraoperative hemorrhage/ LL ischemia/ Distal embolization/ Aortoduodenal fistula
- LL ischemia prevented by minimizing manipulation of aneurysm before clamping, use Fogarty balloon catheter to remove distal emboli
UG: Acute renal failure/ Sexual dysfunction
- Related to use of IV contrast, inadequate hydration, hypotension or renal ischemia
from a period of aortic clamping above renal arteries or embolization to renal
arteries
- Sexual dysfunction and retrograde ejaculation resulting from damage to sympathetic plexus during dissection near the proximal left common iliac artery
CNS: Paraplegia due to spinal cord ischemia
GI: Bowel ischemia/ Prolonged paralytic ileus
- Ischemic colitis from ligation of IMA without adequate collateral circulation
Necrosis limited to mucosa: IV Abx and bowel rest
Necrosis through muscularis propria: segmental stricture needs delayed resection
Transmural necrosis: immediate resection of necrotic colon and end colostomy
Infection: wound or graft
EVAR
Procedure
Placement of modular graft components delivered via the iliac or femoral arteries to line the aorta
and exclude the aneurysm sac from the circulation
Lifelong surveillance is required to assure integrity of the repair
Close FU with CT scan every 6 months for 1 year and then yearly is essential to maintain long-term clinical success with this technique
EVAR
Selection criteria
Aortic neck diameter at the lowest renal artery:
- Required endograft diameter is calculated by adding an additional 15 – 20% of aortic neck diameter to provide sufficient radial force to prevent device migration
- Commercially available devices have endograft diameter largest at 36 mm which allows EVAR to a maximal aortic neck diameter of 32 mm
- Undersizing will lead to inadequate seal and failure to exclude the aneurysm
- Oversizing will lead to incomplete expansion of endograft with infolding and inadequate seal, kinging of device, thrombus formation, endoleak
Aortic neck length: Distance from lowest renal artery to the origin of aneurysm
- at least 10 – 15 mm to provide an adequate proximal landing zone
Aortic neck angulation: < 60o
- Angle formed between points connecting the lowest renal artery, origin of aneurysm and aortic bifurcation
Cone-shaped neck/ Reverse tapered aortic neck:
- Diameter of aorta 15 mm below the lowest renal artery is ≥ 10% larger than diameter of aorta at lowest renal artery
Iliac artery and access vessel morphology in distal landing zone: minimal amount of tortuosity and calcification and no significant stenosis or mural thrombus
EVAR
Complications
Systemic complications
- Vascular injury (e.g. iliac or femoral artery) at entry site
- Arterial dissection
- Bowel ischemia
- Acute renal failure: Secondary to embolization or renal artery occlusion, or contrast-induced nephropathy
Complications related to endografts
- Endoleaks* (Type I and III NOT acceptable): Defined as failure to exclude the aneurysmal sac from arterial blood flow
- Graft infection/ thrombosis/ migration
- Mechanical failures: Graft kinking, separation of components, stenosis, collapse
DVT and PE
Diagnostic criteria
DVT and PE
Radiological investigations
ECG
Sinus tachycardia
S1Q3T3
o S1: Right-axis deviation or deep S wave in lead I
o Q3: Q wave in lead III
o T3: Inverted T wave in lead III
Evidence of right heart strain
o R-axis deviation
o T inversion in V1 – 4
o Incomplete or complete RBBB
CXR
- Hampton’s hump (Wedge-shaped infarction)
- Westermark sign: Avascularity distal to the PE, Demonstration of a sharp cut-off of pulmonary vessels with distal hypoperfusion
- Pleural effusion
- Atelectasis: Decreased ventilation in alveoli that is deprived of blood supply to improve V/Q ratio, or collapse of segment which is infarcted due to embolism
Venous Duplex USG in LL for DVT, Loss of vein compressibility
CT pulmonary angiogram (CTPA): for filling defects in pulmonary trunk
Ventilation-perfusion (V/Q) scan
Echocardiogram (Transthoracic/ Transesophageal): for saddle, left main or right main PE; RV volume and dysfunction;
- McConnell’s sign: Hypokinesis of RV free wall + Normal or hyperkinetic motion of RV apex
DVT and PE treatment
Compare Unfractionated and LMWH
