Acute Lower Limb Ischemia: A Clue to Underlying Aortic Dissection

Naveenraj

First Year Emergency Medicine Resident, Kauvery Hospital, Chennai, India

Abstract

Although not common, acute leg ischemia is an important element in the clinical presentation of a patient with aortic dissection. The incidence of acute lower limb ischemia as a clinical presentation of a patient with underlying acute aortic dissection is almost 26%. This report describes a case of aortic dissection in which the main feature at presentation was acute left leg ischemia. Acute aortic dissection is an acute medical emergency with high mortality rate. Aortic dissection, when suspected, is confirmed by emergency computed tomography. Aortic dissection is potentially lethal if misdiagnosed or if recognition is delayed.

Aortic dissection should also be considered in the differential diagnosis especially in any patient where there is any accompanying severe chest pain, radiating to the back

Background

Aortic dissection is one of the most lethal medical emergencies involving the aorta. In this condition, the innermost layer of the aortic wall, the intimal layer, seems to tear off abruptly and causes the blood to leak through the tear, causing the layers to separate forming a false lumen. As diverted blood flows between the tissue layers, the normal blood flow to lower parts of the body may be slowed or stopped or in worst scenarios cause the aorta to rupture completely.

Case Presentation

A 42-year-aged gentleman, a known hypertensive and diabetic but not on any regular treatment, presented to the emergency room (ER) with acute onset of pain lower abdomen, which was shooting in nature and was associated with pain radiating to left lower limb for 3 h. He was initially treated at an outside hospital with IV analgesics, suspected to have acute left leg ischemia, and referred to us for further management.

Shortly after arrival in the ED, he developed shortness of breath and severe retro-sternal chest pain associated with profuse sweating.

On Examination in the ED:

HR	86/min
BP	140/90 mmHg
RR	26/min
SpO2	99% RA
Temp	Normal
CBG	305 mg/dl
GCS	15/15

Airway: Patent and self-maintained.

Breathing: Breath sounds vesicular, no crepitations.

Circulation: S1S2 heard, muffled heart sounds.

Peripheral pulses:

	Carotid	Brachial	Radial	Femoral	Popliteal	Posterior tibial	Dorsalis Pedis
Right	++	++	++	++	++	++	++
Left	++	++	++	_	_	_	_

Sensation were decreased in the left lower limb and it was cold to touch.

Disability: Moving all four limbs, GCS = E4V5M6(15/15),
- B/L PERL (2mm), No Nystagmus.
Exposure: No external injuries.

In view of unequal limb pulses, BP was measured in all four limbs, to rule out aortic dissection. BP in left lower limb BP significantly reduced compared to left upper limb and right lower limb.

	Right (mmHg)	Left (mmHg)
Upper Limb	140/80	120/70
Lower Limb	130/70	90/60

Other investigations:

ECG: Sinus Arrythmia, HR -70/min, No acute ST-T changes

TROP – I: 0.00 ng/ml (Negative),

ECHO: Normal LV function, Concentric LVH, No RWMA, LVEF:62%

CHEM8

Na	143mmol/L
K	4.3mmol/L
Cl	109mmol/L
Tco2	20mmol/L
Glucose	220mg/dL
BUN	12mg/dL
Creatine	0.8mg/dL
Hb	12.2g/dL

A provisional diagnosis of a probable acute aortic dissection with left leg acute ischemia was made.

The patient then was shifted for urgent CT Aortogram and both lower limb peripheral angiogram.

They indicated which Aortic dissection starting at aortic sinus level extending into whole of the aorta and bilateral common and external iliac artery. There was severe narrowing with occlusion of true lumen from left external iliac artery origin to distal external iliac artery and left lower limb arterial system perfused through false lumen with delayed filling of left tibial and peroneal arteries.

The diagnosis of Aortic dissection with occlusion of left iliac artery (Stanford Type A) was confirmed and need for immediate surgical management was advised.

Discussion

Acute limb ischemia associated with aortic dissection is a true medical emergency with indication for surgical management to perform aortic repair. Delaying aortic repair for limb reperfusion procedures results in unacceptably high mortality rates. Aortic dissection is a catastrophic illness with protean manifestations. The prognosis of untreated aortic dissection is dismal, 25% mortality within 24 h, 50% within 1 week, 75% within 1 month, and 90% within 1 year. Aortography still remains the most definitive tool for confirming the diagnosis of acute aortic dissection.

Risk of death from aortic rupture must be weighed against the risk of malperfusion-related organ damage.

For uncomplicated Stanford Type B Aortic dissection, patients can be managed medically. Prompt action and treatment can save up to 70% who have Type A dissection and about 90% who have Type B dissection who shall survive to leave the hospital.

Use of thrombolytics, anticoagulants, and antiplatelet therapy may be catastrophic if the diagnosis of aortic dissection is missed when evaluating acute limb ischemia.

Conclusion

Aortic dissection presented with lower extremity ischemia is not common but early diagnosis and prompt action can increase the survival of patients. Considering the high morbidity and mortality rate associated with delayed recognition or misdiagnosis of aortic dissection, we should keep it as a differential diagnosis in patients presenting with non-traumatic acute lower limb ischemia with associated chest pain.

Acknowledgements

I would like to thank Dr. Aslesha Sheth, Consultant and Clinical Lead, Dept of Emergency, and Dr. Karunkaran Vetri, Consultant, Department of Emergency. For their guidance in writing this article.

References

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Acute Lower Limb Ischemia: A Clue to Underlying Aortic Dissection