On September 11th, 2003, John Ritter, known famously for his starring role in Three's Company, developed chest pain, nausea and diaphoresis while filming 8 Simple Rules for Dating My Daughter. 54 years old at the time, he presented to the Providence Saint Joseph Medical Center at 6pm and was seen by an ER doctor who ordered bloodwork, an EKG and a chest x-ray. Based on EKG changes (unclear what they were exactly), Ritter was diagnosed with a myocardial infarction (MI) and started on anticoagulation. The chest x-ray was ordered but never completed.
About an hour later he acutely worsened. Assuming it was a large MI, he was rushed to the cardiac cath lab where they discovered he in fact had an aortic dissection. He was emergently sent to surgery but sadly did not survive and was pronounced dead just before 11pm that night.
A 2004 lawsuit was filed by Mr. Ritter's widow arguing that if the chest x-ray was done, he would have survived.
Is this claim valid? And could POCUS have saved his life?
The aortic dissection was first described as far back as 1760 when George the II awoke one morning and promptly fell to the ground. His Valet de Chambre "heard a noise, memorably described as "louder than the royal wind," and then a groan; he ran in and found the King lying on the floor, having cut his face in falling."
He died minutes later.
At autopsy, the doctor discovered a "pericardium distended with a pint of coagulated blood, probably from an orifice in the right ventricle, and a transverse fissure on the inner side of the ascending aorta 3.75 cm long, through which blood had recently passed in its external coat to form a raised ecchymosis, this appearance being interpreted as an incipient aneurysm of the aorta."
One of the first to describe the pathophysiology of aortic aneurysms and dissection was a physician named Thomas Bevill Peacock. Originally famous for his 1858 work on congenital heart disease, he published a case series of 19 patients who died of aortic dissection, and his findings were remarkably accurate.
He noted that aortic dissection was more common in the elderly, and that "the coats of the aorta are, in a healthy state, capable of extreme distension before giving way . .. the rupture of the internal coats of the vessel . .. must be ascribed to their being rendered lacerable by disease."He also recognized a difference in pathophysiology and prognosis of an ascending thoracic aortic dissection which "the extravasated blood readily makes its way into the sac of the pericardium . .. and death is almost instantaneous," and a descending thoracic aortic dissection in which the blood "tends to separate the coats in the lower portion of the vessel and rarely makes it way to its origin," making it less deadly.
Epidemiology & Presentation
Aortic dissection is a rare but deadly condition. It makes up only 3 out of every 100,000 ED presentations, making it extremely difficult to piece out amidst the thousands of presentations of cardiac related chest pain each year. Based on an International registry of aortic dissections including 464 patients, the most common presenting symptom was abrupt onset chest pain in 84% of patients. Anterior chest pain associated with Type A dissection (Type A = in the ascending portion of the aorta), while back/scapular pain was more associated with a Type B dissection (in the descending portion of the thoracic aorta), however there was overlap in symptoms.
Type A dissections are considered a surgical emergency (because as Dr Peacock noted, are more likely to cause sudden death), while Type B dissections are often managed medically.
Hypertension was more common in patients with Type B dissection, and in fact 1/4 patients with Type A dissection had initial systolic pressure below 100. A pulse deficit was noted in only 15% of cases, and 2/3 of Type A dissections reported a diastolic murmur.
Chest X-ray Imaging
Overall chest x-ray imaging for aortic dissection isn't great. In the 464 patients from the international aortic dissection registry, 37% with Type A dissection had absence of mediastinal widening seen on chest x-ray. Similarly in another study of 216 patients, chest x-ray had a sensitivity of 64% and a specificity of 86% for aortic disease, and 67% sensitive for overt aortic dissection.
POCUS for diagnosing thoracic aortic dissection
POCUS could offer a point of care solution to evaluate for aortic dissection, especially for Type A dissections. Given the location of the aorta behind major organs, and its overall size, ruling out aortic dissection completely with POCUS alone is difficult. In older studies from the 1980s and 1990s, specificities and sensitivities for trans thoracic echo has varied from 30-80%. One study from 1993 had standard echo and suprasternal aortic evaluation for detecting aortic dissection at only 59% sensitivity and 83% specific overall, but ~80% sensitive for Type A dissections.
In more more recent studies, echo performs much better.
Another study from 2009 evaluated 143 patients with suspected acute dissection. The transthoracic echo looked at parasternal long, parasternal short, subcostal, apical, suprasternal and abdominal views, and they compared their images with and without contrast, arguing that with the newer ultrasound machines with better image quality the diagnostic accuracy would be better. Overall, without contrast, TTE has sensitivity and specificity of about 70-80% for ascending aorta and aortic arch.
Contrast enhancement (which is not practical for POCUS) makes differentiating flow patterns easier. In this study it improved accuracy to trans-esophageal echo (TEE) levels in the ascending aorta (93% sensitive and 97% specific) and in the aortic arch (sensitivity 90.7%, specificity 99%), and dramatically improved accuracy in descending aorta though not as good as TEE (from 56% to 83% sensitive).
A retrospective analysis from 2015 of 178 patients with acute ascending aortic dissection (Type A) were evaluated with CT, transthoracic echo, and intraoperatively during the repair. CT as expected revealed 100% of the dissections.
The presence of intimal flap in ascending aorta was seen with ultrasound in 92% of the cases. There were also benefits of using echo over CT, such as evaluating for bicuspid aortic valve, AV calcifications, moderate/severe aortic incompetence or cardiac tamponade. The authors concluded that TTE was "not inferior to computed tomography in diagnosis of acute type A aortic dissection with reference to the intra-operative finding." However these results were certainly biased by the fact that they already had a very high suspicion that at Type A dissection was present or likely present when performing the echo.
In 2012, TTE was used to evaluate 270 patients with suspected Acute Type A Aortic Syndrome (AAAS). Overall TTE had a sensitivity and specificity of 87 and 91%. In the studies that were deemed "image optimal," the numbers were even better: sensitivity of 97% and specificity of 100%.
Chest X-ray and POCUS in the Ritter case
It is clear that the chest x-ray may have picked up evidence of an aortic aneurysm or dissection however as we mentioned the sensitivity was quite poor. Ultimately the doctors involved in the case were cleared of negligence and John Ritter's wife created the John Ritter Foundation for Aortic Health to raise awareness and funding for this rare but devastating condition.
Presenting in 2003, the data on ultrasound prior to that time seemed to suggest that point of care ultrasound may not be very sensitive for picking up acute dissections. However after 1999, harmonics (a technique that employs the resonance characteristics of tissue to improve the resolution and reduce artifact) was introduced into echo and the diagnostic accuracy for POCUS to detect ascending thoracic dissection was much greater.
At the very least, it would have given the ER doctors a view of the heart and answered the following questions with certainty:
- Was there a pericardial effusion or tamponade?
- Was the Ejection fraction normal?
- Were there obvious wall motion abnormalities that correspond to the EKG changes?
- Was the aortic root dilated?
- Was there aortic regurgitation?
- Was the descending aorta dilated?
All of these questions could definitely have been answered by POCUS and may have helped come to the diagnosis quicker. This case is a good example of why we argue that every patient with chest pain requires a basic cardiac POCUS exam.