Emergency diagnosis and treatment of aortic dissection



Yüklə 10,93 Mb.
tarix06.02.2017
ölçüsü10,93 Mb.
#7772


EMERGENCY DIAGNOSIS AND TREATMENT OF AORTIC DISSECTION

  • Alan C. Braverman, M.D.

  • Washington University School of Medicine

  • Richard Devereux, M.D.

  • New York Hospital/Cornell Medical Center

  • Reed Pyeritz, M.D., Ph.D.

  • University of Pennsylvania School of Medicine

  • Joseph Coselli, M.D.

  • Baylor College and Methodist Hospital


HISTORY

  • 1761: Morgagni. Described dissecting aneurysm.

  • 1804: Scarpa. Dissection related to “corrosion and rupture of the proper coats of the aorta.” Hematoma resulting from blood dissecting through the arterial wall.

  • 1826: Laennec. Introduced term “dissecting aneurysm.”

  • 1855: First antemortem diagnosis of dissection

  • 1843-1863:

  • Thomas Peacock. Cadaver experiments.

  • 1. Ruptured intima (“lacerable”)

  • 2. Blood penetrating the media

  • 3. Distal reentry (“imperfect natural cure”)



HISTORY cont’d.

  • 1864: von Recklinghausen. Attributed dissection to molecular changes in elastic tissue

  • 1910: Babes, Mironescu. Aortic dissection could occur secondary to hemorrhage in vasa vasorum “dissecting mesarteritis.”

  • 1910: Moriani. Microscopic changes in elastic tissue and connective tissue of media

  • 1929: Erdheim. Cystic medial necrosis as underlying cause.

  • 1934: Shennan. “Dissecting aneurysms”

  • - degeneration of media frequent

  • - neither atheroma nor lues were important



HISTORY cont’d.

  • 1943: Oppenheimer and Taussig. First described ascending aortic aneurysm in the Marfan syndrome

  • Etter and Glover. First described ascending aortic dissection in the Marfan syndrome

  • 1955: McKusick. Documented that aortic dissection is a common cause of death in the Marfan syndrome

  • 1958: Hirst. Review of 505 cases.

  • Atherosclerosis not a related factor.

  • 1973: Gore and Hirst. Rupture of vasa vasorum initiating event.



PATHOGENESIS

  • 1. Intimal Tear as Primary Event

  • Propagation of dissecting hematoma within media.

  • Intramural hemorrhage due to rupture

  • - Intimal tear is a secondary event.

  • - Propagation of cleavage plane by

      • pulsatile force of blood.


RISK FACTORS

  • ROLE OF ABNORMAL AORTIC MEDIA

  • Cystic medial necrosis (Erdheim)

  • - Not always present in dissecting aorta

  • - Also present in patients without dissection

  • Aortic dissection associated with connective tissue diseases

  • - The Marfan syndrome, Ehlers-Danlos

  • - Aortic dilation (thoracic or abdominal, often familial)

  • Aortic dissection associated with

  • - Bicuspid aortic valve

  • - Aortic coarctation

  • - Turner syndrome



RISK FACTORS cont’d.

  • Marfan syndrome

  • (Present in 5-10% of ascending aortic dissections, .02% of adults)

  • Aortic dilatation

  • Bicuspid aortic valve, coarctation

  • Turner, Ehlers-Danlos (type IV), Noonan syndrome

  • Family history of…

  • Marfan syndrome, aortic dissection, aortic disease

  • Hypertension

  • (Present in 70-90% of dissections, but 20-40% of adults)



MARFAN SYNDROME

  • FEATURES

  • Very long arms, fingers, toes

  • Pigeon breast or severe pectus carinatum

  • Moderate or severe scoliosis

  • Dislocated lenses

  • Family history of the Marfan syndrome



1995 GHENT NOSOLOGY

  • INDEX CASE: Major criteria in two systems and involvement of a third system

  • FAMILY MEMBER: One major criterion in an organ system and involvement of a second organ system



CARDIOVASCULAR SYSTEM

  • MAJOR CRITERIA

  • dilation of ascending aorta

  • aortic dissection

  • MINOR CRITERIA

  • mitral valve prolapse

  • dilation of a main pulmonary artery

  • premature mitral anular calcification (<40yrs.)

  • descending thoracic or abdominal aortic aneurysm (< 50 yrs.)

  • Cardiovascular involvement: one minor criterion



OCULAR SYSTEM

  • MAJOR CRITERION

  • Ectopia lentis



SKELETAL SYSTEM

  • MAJOR CRITERIA

  • Presence of at least four of the following:

  • pectus carinatum

  • pectus excavatum requiring surgery

  • reduced upper to lower segment ratio or arm span to height ratio > 1.05

  • wrist and thumb signs

  • scoliosis > 20° or spondylolisthesis

  • reduced extension at the elbows (<170°)

  • medial displacement of the medial malleolus causing pes planus

  • protusio acetabulae of any degree















PROLONGING LIFE

      • Correct Diagnosis
      • Medical Management
      • Surgical Repair


DIAGNOSIS

  • Clinical Evaluation

  • Complete physical examination, including a careful musculoskeletal and skin examination

  • Detailed medical and family history

  • Electrocardiogram (EKG) and echocardiogram, looking for cardiovascualr involvement

  • Eye examination by an ophthalmologist, who dilates the pupil and uses a slit lamp to assess for lens dislocation



MANAGEMENT

  • UNDERLYING PRINCIPAL:

  • Weak connective tissue cannot withstand normal tension on aorta.

  • Since T~P x R

  • Avoid strenuous exercise that increases BP.

  • Use medicine to lower BP and dP/dT.

      • ß-blockers
      • Verapamil
      • Other calcium blockers or ACE inhibitors that lower BP
  • Replace aortic root/valve when aortic diameter > 6.0 cm without AR or > 5.0 cm with 3+ - 4+ AR.



ETIOLOGIC MECHANISM

  • Intimal tear with secondary extension into media

  • Hemorrhage into media precipitating secondary intimal tear

  • Intramural hematoma

  • Penetrating atherosclerotic ulcer



CLASSIFICATION

  • DEBAKEY

  • Type I

  • Ascending aorta extending beyond arch

  • Type II

  • Ascending aorta only

  • Type III

  • Desending aorta

  • Type IIIb

  • Descending aorta extending below diaphragm







CLASSIFICATION cont’d.

  • ASCENDING

  • DISSECTIONS

  • 65-75% of dissections

  • Entry tear within a few centimeters of aortic valve

  • 50% extend to iliac bifurcation





COMPLICATIONS

  • 1. Rupture through outer wall of false channel

  • *typically directly across from entry tear

  • - pericardial tamponade

  • - mediastinal or pleural rupture

  • - exsanguination

  • 2. Acute Aortic Regurgitation

  • *50% of ascending dissections

  • - medial split undermines support of aortic valve

  • - may lead to severe CHF







COMPLICATIONS cont’d.

  • 3. Branch Vessel Compromise

  • - extension of dissection into a branch vessel

  • - compression of orifice by intimal flap

  • Clinical Scenarios

  • - stroke

  • - paraplegia

  • - HTN-renal failure

  • - visceral ischemia

  • - MI

  • 4. Aneurysmal Dilation and Subsequent Rupture







CLINICAL FEATURES

  • Incidence uncertain.

  • Available information: 5,000 – 10,000 cases/year in U.S.

  • Number may be higher (not reportable condition, few autopsies now)

  • Autopsy series – 0.2% autopsies

  • Males 2-5 times more frequent than females

  • Ascending dissections: 50-55 years old

  • (<40 years: Marfan, pregnancy, AV disease)

  • 5. Descending dissections: 60-70 years old



CLINICAL FEATURES cont’d.

  • Most important factor

  • leading to a correct diagnosis is

  • a high clinical suspicion!



CLINICAL FEATURES cont’d.

  • Sudden Onset Severe Pain

      • May or may not be catastrophic
      • Ripping, tearing
      • Migratory
      • Never experienced before
      • Restless, sense of doom
  • Look for underlying connective tissue disorder

  • 3. Hypertension (especially moderate or severe)

  • or known aortic aneurysm



PAIN CHARACTERISTICS

  • SEVERE PAIN (90%)

  • Most Severe at Onset

  • Anterior Pain: Proximal Dissection

  • Posterior Pain: Distal Dissection

  • Migratory Pain

  • Pain in these locations usually due to other more common disorders (MI, pneumonia, pleurisy, pulmonary embolism, pneumothorax, ulcer, cholecystitis, pancreatitis)

  • Must consider aortic dissection in cases without other confirmed cause of pain.



CLINICAL FEATURES



PHYSICAL EXAMINATION

  • Acutely ill

  • Hypertension (catecholamines, renal ischemia)

  • Hypotension (20%): acute complications

  • Aortic insufficiency: (50-60% ascending dissections)

  • Pulse deficits: (60% ascending dissections)

      • May change over time
      • Be wary the pt with acute (L) leg ischemia and negative embolectomy
  • Other



NATURAL HISTORY

  • Autopsy Series: >50% of people with untreated aortic dissections are dead within 48 hours.

  • 1934 Shennan: >300 cases reviewed.

    • 40% acute ascending dissections died suddenly.
    • None lived > 5 weeks
  • Anagnostopoulos et al. Am J Card 1972

    • 973 pts with untreated proximal and distal dissections
    • 50% died with 48 hours
    • 84% died within 1 month
  • 1% per hour risk of death in first 48 hours



Acute 0-14 days

  • Acute 0-14 days

  • Chronic 14+ days



DIAGNOSTIC EVALUATION

  • Chest radiograph

  • Transthoracic echocardiogram

  • Transesophageal echocardiogram*

  • Computed tomography*

  • Magnetic resonance imaging*

  • Aortography

  • *Choose based on rapid availability and quality of performance



CHEST X-RAY

  • Signs of dissection are indirect

    • Abnormal aortic knob, widened mediastinum, pleural effusion
  • Insensitive with variable inter-observer agreement

  • Look for changes compared with old films

  • Displaced intimal calcification (>5 mm) – useful in older patients

  • Normal in 18%

    • A Normal CXR Should Not Deter Further Evaluation.






TRANSESOPHAGEAL ECHO

  • Procedure of first choice for dissection, if readily available

  • Portability of equipment facilities emergency management by cardiologist in ER or ICU

  • High sensitivity and specificity

  • Additional information: - aortic regurgitation

  • - pericardial effusion

  • - ostia of coronary arteries

  • - LV function







COMPUTED TOMOGRAPHY

  • Rapid IV bolus and sequential imaging

  • 88-100% accuracy

  • Limitations:

    • no evaluation of aortic regurgitation
    • Limited information on branch vessels
    • “streak artefacts” may cause false (+)
    • (Bone-air interface may simulate flap)
    • False (-) from poor bolus of contrast
  • Useful for follow-up of dissections



MRI

  • Good alternative to TEE or CT, if readily available

  • High sensitivity and specificity

  • Can detect slow blood leaks

  • Non-invasive; neither x-rays nor contrast needed

  • 90-100% accuracy

  • Limitation: requires patient to be in claustrophobic apparatus without standard ECG monitoring

  • Useful for follow-up of dissections



AORTOGRAPHY

  • Identify intimal flap, true and false lumen

  • Thickened wall (thrombosed false lumen)

  • Aortic insufficiency, branch vessel involvement

  • Diagnostic accuracy 90-95%

  • 5-10% false (-) rate

        • thrombosed false lumen
        • simultaneous opacification of both lumens
        • misses intramural hematoma
  • Risks of procedure (time delay in type A)

  • Coronary angiography usually not necessary in acute ascending dissection (surgeon can inspect coronaries)



TREATMENT

  • ICU admission in a tertiary center

  • Immediate cardiothoracic surgical consultation

  • Close observation of BP, urine output, neurologic status

  • Prompt blood pressure control is critical

      • Can reduce propagation of dissection
      • Decrease BP and LV contractility to decrease dP/dt
        • Sodium nitroprusside + b – blocker
        • and - blocker, Calcium channel blocker
          • (heart rate slowing)


INDICATIONS FOR SURGERY

  • Consider operative treatment for all patients

  • Hypotension: Emergency surgery

  • Ascending Dissection: Emergency surgery

  • Descending Dissection:

      • Operation in acute phase no difference in survival compared to medical therapy 35-75% mortality
      • Higher risk of surgery with renal failure, visceral ischemia, age > 70 years
  • Risk of surgery inversely related to experience with dissection surgery



GOALS OF SURGERY

  • Excise the intimal tear

  • Obliterate entry into false lumen proximally and distally

  • Reconstitute the aorta (Dacron graft)



GOALS OF SURGERY cont’d.

  • If aortic regurgitation complicates ascending dissection:

      • Surgical decompression of false lumen and resuspension AV leaflets
      • Aortic valve replacement required if annular supports of leaflets damaged (composite graft or homograft)
      • Aortic valve replacement required if aortic root >5 cm (likely to progress)






INDICATIONS FOR SURGICAL THERAPY

  • Hemorrhage or rupture

  • End-organ ischemia

  • Continued pain

  • Rapid expansion (>5mm in 6 months) of diameter of any segment >6 cm

  • (less in some centers)

  • Uncontrolled HTN

  • Younger patients at relatively good operative risk



FOLLOW-UP

  • Aneurysmal dilation and rupture are leading causes of late death

  • 1982 DeBakey. 527 pts operated for aortic dissection: 30% of late deaths due to rupture of post-dissection aneurysms

  • 1990 Crawford. Death from rupture occurred in 12/130 (9%) cases with a dilated but unrepaired residual aorta

  • After extensive aortic dissection, many patients will eventually require surgical therapy (especially if on anticoagulants after composite graft repair)



FOLLOW-UP cont’d.

  • Before hospital discharge: CT scan or MRI

  • Initial evaluation after discharge: CT scan or MRI at 3, 6 and 12 months

  • Reimage aorta every 6-12 months thereafter

  • Meticulous control of blood pressure dP/dt (starting with b-blocker or heart rate slowing calcium channel blocker)

  • Avoid isometric exercise.



SURGICAL THERAPY

  • Early operations attempted to create reentry passage or restoration of circulation to ischemic branches. High failure rate.

  • 1935 Gurin: Fenestrated dissecting membrane in iliac artery.

  • 1948 Paullin and James: Wrapped chronic dissection of descending aorta with cellophane.



SURGICAL THERAPY cont’d.

  • 1955 Michael DeBakey: Modern treatment of aortic dissection

  • Collegues: Denton Cooley and O’ Creech

  • 1st case: Descending thoracic dissection

      • Excision of aneurysmal dilation
      • Oversewed distal entry into the false channel
      • End-to-end anastomosis of aorta
  • Later: Dacron graft replacement of descending aorta

  • 5. 1962 Spencer and Blake: First successful repair of chronic ascending dissection with resuspension of aortic valve commissures



SURGICAL THERAPY cont’d.

  • 1960’s: Importance of sandwiching the friable aortic layers between strips of Teflon felt

  • Bentall procedure

  • Evolution of the composite graft approach

  • Aortic homograft

  • Aortic conduit with AV sparing



  • Distributed by:

  • 22 Manhasset Ave

  • Port Washington, NY 11050

  • (800) 8-MARFAN

  • www.marfan.org



Yüklə 10,93 Mb.

Dostları ilə paylaş:




Verilənlər bazası müəlliflik hüququ ilə müdafiə olunur ©www.azkurs.org 2022
rəhbərliyinə müraciət

    Ana səhifə