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A Patient With Chest Pain of Sudden Onset




Liability cases can be challenging. MD News uses an example of an actual case to show you how to handle the situation.

On March 9 at 2 p.m., a 42-year-old male with a history of hypertension and cocaine abuse presented to the Emergency Department (ED) with complaints of severe chest pain of sudden onset. His blood pressure was 167/106; pulse rate, 86; respirations, 18; and temperature, 98.7.

He was started on lisinopril and given nitroglycerin. A chest X-ray showed an enlarged cardiac silhouette and prominent right hilum. A CT scan with contrast was ordered, but the IV infiltrated, so the CT was done without contrast. It showed diffuse infiltration of the mediastinum, a moderate-sized high attenuation pericardial effusion and dilation of the ascending aorta measuring 5 cm (normal 4 cm) at the level of the right pulmonary artery.

The radiologist discussed the findings with the emergency physicians. He considered the results inconclusive and strongly recommended a repeat CT with contrast. It was never done. At 11 p.m., the patient was admitted to ICU with a working diagnosis of pulmonary embolism (PE) and poorly controlled hypertension. A heparin drip was started. A subsequent ventilation/ perfusion lung scan was normal, essentially ruling out PE. The consulting pulmonologist's diagnosis was pericarditis, and he started the patient on indomethacin.

The ICU resident reviewed the CT scan with the radiologist, who expressed concern about possible hemopericardium. The resident called our insured cardiologist on the morning of March 10, and they agreed to discontinue heparin until hemopericardium was ruled out. The insured said he would see the patient in consultation and suggested a 2-D transthoracic echocardiogram (TTE) to assess the potential hemopericardium. The resident ordered the TTE that night, but did not write an order for a cardiology consultation. The TTE was interpreted by the cardiologist, who described a 200 cc pericardial effusion, stating there was no evidence of tamponade. The aortic root was said to be normal in size; the size of the ascending aorta was not mentioned.

The patient continued on indomethacin. His ongoing chest pain was managed with Dilaudid. He seemed stable and was transferred from the ICU to the medical floor on the afternoon of March 10, under the care of a hospitalist. He was found dead in his room on March 11 before being seen by the cardiologist. An autopsy revealed pericardial tamponade secondary to an aortic dissection that began 3 cm above the aortic valve, just below the reflection of the pericardial sac.

Expert Opinions

Three cardiologists opined the ED physicians should have immediately performed a CT with contrast in accordance with the radiologist's recommendation. Had that been done, the dissection would have been diagnosed. They agreed that the TTE showed no dissection, aortic regurgitation or tamponade, but they added that a TTE will not usually show dissections of the distal ascending aorta. They felt the insured's failure to mention the aortic root enlargement and ascending aortic dilation was a breach in the standard of care because these findings indicated the need for an urgent follow-up test, such as an MRI or a transesophageal echocardiogram (TEE) to rule out dissection.

A cardiothoracic surgeon believed the patient would have survived surgery if the dissection had been diagnosed. He opined that the CT scan was suggestive of dissection because it showed blood in the mediastinum and that the patient's presenting symptoms were consistent with dissection. He opined that diagnosing pericarditis without ruling out aortic dissection was inappropriate.

A radiologist examined the CT films and found them suspicious for dissection, even without contrast, because they revealed infiltration of blood into the mediastinum. He believed that if the CT had been repeated with contrast, the dissection would have been revealed.

Claim Analysis

The codefendant hospital's ED physicians faced the greatest liability due to their failure to order a repeat CT scan with contrast. The hospital claimed that the insured cardiologist was a consultant with responsibility for managing the patient. The defense counsel responded that the insured was not involved in establishing the differential diagnosis and never saw the patient. However, the TTE report stated that the patient was referred by the pulmonologist for evaluation of chest pain and pericardial effusion. The defense counsel pointed out that when the insured cardiologist interpreted the TTE, he was unaware of the CT scan suggestive of possible dissection. If he had seen that report, our insured said he would have ordered a CT scan with contrast or an MRI because of the known limitations of TTE in diagnosing aortic dissection.

The case was settled, with the hospital contributing 50% and the pulmonologist and insured cardiologist each contributing 25%.

Discussion

It is important to rapidly identify acute dissections involving the ascending aorta, which are considered surgical emergencies. Hemodynamically stable dissections confined to the descending aorta are treated medically.

The Daily (Stanford) system classifies dissections that involve the ascending aorta as type A and all other dissections as type B. Ascending aortic dissections are almost twice as common as descending dissections. Aortic arch involvement is seen in up to 30% of dissections.

The most important predisposing factor is hypertension (72% overall and more common in type B). Under age 40, only 34% have hypertension. Marfan syndrome is present in 50% of those under age 40. Most patients with Marfan syndrome and aortic dissection have a family history of dissection.

Other predisposing factors, especially in younger patients, include aortic aneurysm (13%), bicuspid aortic valve (9%), previous aortic valve replacement (5%), cardiac catheterization (2%), weight lifting or other strenuous resistance training, and crack cocaine abuse.

Clinical Manifestations

Patients with acute aortic dissection typically present with abrupt onset of severe, sharp or "tearing" posterior chest or back pain (in dissection distal to the left subclavian) or anterior chest pain (in ascending aortic dissection). The pain can radiate anywhere in the thorax or abdomen. Other symptoms relate to impaired blood flow to an organ or limb induced by the dissection or its propagation. Impaired or absent blood flow to peripheral vessels is manifested as a weak or absent carotid, brachial or femoral pulse.

Descending aortic dissection can lead to splanchnic ischemia, renal insufficiency, lower extremity ischemia or focal neurologic deficits due to spinal artery involvement. Ascending aortic dissection can induce one or more of the following:

  • Acute aortic insufficiency leading to a diastolic decrescendo murmur, hypotension or heart failure. The murmur is most commonly heard along the right sternal border, as compared with the left sternal border when insufficiency is due to primary aortic valve disease.
  • Acute myocardial ischemia or MI due to coronary occlusion, most commonly involving the right coronary artery.
  • Cardiac tamponade and sudden death due to rupture into the pericardium.
  • Hemothorax if the dissection extends into the pleural space.
  • Variation (>20 mm Hg) in systolic blood pressure between the arms.
  • Syncope, stroke or decreased consciousness due to direct extension of the dissection into the carotid arteries.

Diagnosis

Aortic dissection is suspected from the history and physical examination. An analysis of 250 patients with acute chest and/or back pain found that 96% of acute aortic dissections could be identified based upon some combination of three clinical features:

  • Abrupt onset of thoracic or abdominal pain with a sharp, tearing and/or ripping character
  • Mediastinal and/or aortic widening on chest radiograph
  • A variation in pulse (absence of a proximal extremity or carotid pulse) and/or blood pressure (>20 mm Hg difference) between right and left arms Because conventional chest radiographs show mediastinal widening in only 63% of type A dissections and 56% of type B dissections, additional imaging studies are usually obtained.

Electrocardiogram (ECG)

The nature and location of the chest pain and the absence of ECG changes characteristic of ischemia usually allow aortic dissection to be distinguished from angina pectoris or an MI. In a review of 464 patients, the ECG was normal in 31%, showed nonspecific ST and T wave changes in 42%, ischemic changes in 15%, and, among patients with an ascending aortic dissection, evidence of an acute MI in 5%.

Imaging Studies

Aortography has been largely replaced by noninvasive testing. It has a reported sensitivity of 88% and a specificity of 94%. The positive and negative predictive values are 96% and 84%, respectively. CT scan (with contrast) is often the initial screening study, especially in the ED setting where TEE and MRI are less available, especially after hours. In two reports of 162 and 110 patients, the sensitivity of standard CT for the diagnosis of aortic dissection was 83% and 98%, and the specificity was 87% and 100%. Accuracy is improved with spiral (helical) CT.

MRI is highly accurate for evaluating the thoracic aorta in suspected dissection. In a prospective trial of 110 patients with suspected aortic dissection, the sensitivity and specificity of MRI were each 98%.

TTE has limited utility for evaluation of aortic dissection because of its inability to adequately visualize the distal ascending, transverse and descending aorta in most patients. TTE is most useful for assessing cardiac complications of dissection, including aortic insufficiency and pericardial effusion/tamponade.

Multiplane TEE can be performed in the ED, although it requires esophageal intubation. The following may be seen: intimal dissection flaps, true and false lumens, pericardial effusion, concomitant aortic regurgitation and visualization of the proximal coronary arteries. In three large series, the sensitivity of TEE for the diagnosis of aortic dissection was 97% to 99%. However, the specificity of TEE alone has been as low as 77% to 85%.

The guidelines suggested in this article are not rules, do not constitute legal advice and do not ensure a successful outcome. They attempt to define principles of practice for providing appropriate care. The principles are not inclusive of all proper methods of care nor exclusive of other methods reasonably directed at obtaining the same results.

The ultimate decision regarding the appropriateness of any treatment must be made by each health care provider in light of all circumstances prevailing in the individual situation and in accordance with the laws of the jurisdiction in which the care is rendered.

References
The following reference is from UpToDate, Rose BD (Ed), UpToDate, Waltham, MA 2008. Copyright 2008 UpToDate, Inc. Accessed on June 10, 2009. For more information, visit www.uptodate.com.
Manning WJ. Clinical manifestations and diagnosis of aortic dissection. Last literature review completed through May 2009.

MD News February 2010


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