a b s t r a c t

Chest pain is a commonly encountered emergency department complaint, with a broad differential including sev- eral life-threatening possible conditions. Ultrasound-assisted evaluation can potentially be used to rapidly and ac- curately arrive at the correct diagnosis. We propose an organized, ultrasound assisted evaluation of the patient with chest pain using a combination of ultrasound, echocardiography and clinical parameters. Basic echo tech- niques which can be mastered by residents in a short time are used plus standardized clinical questions and exam- ination. Information is kept on a checklist. We hypothesize that this will result in a quicker, more accurate evaluation of chest pain in the ED leading to timely treatment and disposition of the patient, less provider anxiety, a reduction in the number of diagnostic errors, and the removal of false assumptions from the diagnostic process.

(C) 2017

1. Introduction

Chest pain is a commonly encountered emergency department com- plaint, with a broad differential including several life-threatening possi- ble conditions. Emergency physicians are faced with the challenge of rapidly differentiating among myocardial infarction, pulmonary embo- lus, aortic dissection, costochondritis, torn intercostal muscle, percarditis and many other causes of non-traumatic chest pain. Even abdominal pa- thology, such as biliary colic or esophagitis can present as chest pain. Rapid laboratory testing and imaging have shortened the time between initial patient-physician encounter and final diagnosis. Can accuracy and speed be further improved?

* Corresponding author.

E-mail address: [email protected] (M.D. Colony).

Ultrasound devices capable of creating images of the heart, aorta and lungs have improved vastly since the invention of the first echo machine in 1948. These original machines were large and cumbersome [38].

Today’s echocardiography machines are slick technical devices capa- ble of instantly delivering high quality, real-time images and detailed measurements. Higher end machines can overcome imaging obstacles such as patient obesity, the presence of emphysema, and difficulty in positioning the patient into the “reclining Greek God” position in which the heart falls against the chest wall. In fact, a modern machine with color flow Doppler capabilities can be carried in the examiner’s

https://doi.org/10.1016/j.ajem.2017.09.003

0735-6757/(C) 2017

pocket, ready for use to evaluate heart, lung, aortic root and aortic arch, gall bladder, AAA, IVC and any other suspect organs. Emergency Physi- cians should be using these tools to accelerate attaining a correct diagno- sis in the evaluation of chest pain [11].

In 1987, the television actor John Ritter was taken to a hospital and evaluated for chest pain. In the face of normal troponin and ECG and X- ray, Mr. Ritter was sent home. When he subsequently returned with more chest pain, his EKG showed ST elevations, and he was started on heparin and taken to the interventional catheterization lab for a presumed

acute MI. Upon the initiation of angiography, the patient began losing blood pressure and the operators discovered that what he actually had was a thoracic aortic dissection. He subsequently suffered cardiac arrest and died [35]. Similarly, in 1996, Jonathan Larson, the creator of the musi- cal Rent, died of a misdiagnosed aortic dissection just prior to the show’s opening. In both cases, these patients might have been saved had the phy- sicians caring for them had access to bedside echocardiography. Two sim- ple views, a Parasternal long axis and a Suprasternal notch view might have changed the entire clinical course for these two patients [1].

The average emergency medicine resident can easily master the skills necessary to quickly and accurately perform bedside ultra- sound [3,32]. These skills, applied as part of a systematic exam of the thoracic contents and coupled with clinical questions, will lead to the correct diagnosis much more reliably than the old fashioned “stethoscope and meet and greet” exam. This examination is called “Chest and cardiac assessment with Sonographic Exam (Chest CASE).”

1. Literature survey

A review of the literature as far back as 1992 reveals an increasing in- terest in the use of point of care echocardiography for the evaluation of chest pain [33]. Plummer, Brunette, et al. reported a case [4] in the An- nals of Emergency Medicine in 1992 wherein ultrasound was used to di- agnose Pericardial tamponade in Penetrating cardiac injury. Initial interest in ultrasonic evaluations in the ED for trauma, branched out to studies of non-traumatic chest pain Jackson et al. [5] showed that that the findings of acute pulmonary embolism were a dilated right ven- tricle with a ratio of RV to LV diameters to be greater than the normal ratio of 0.6:1. A dilated, stunned right ventricle produced McConnell’s sign: the apex of the heart contracts while the adjoining RV free wall is dragged passively along. They also noted that acute increase in pul- monary artery systolic pressure, easily measured by echo using contin- uous wave Doppler across the Tricuspid valve, represented an obstructed RV outflow tract or pulmonary artery. Advanced users were even able to view clot in the pulmonary artery, or clot in transit seen in the IVC or the RA. Others advocated the use of the “60-60” rule, e.g. the increase in regurgitation velocity across the tricuspid valve was above 2.5 but b 6.0 m/s and at the same time the pulmonary valve acceleration time (time from initial to peak velocity across pul- monic valve) was b 60 ms [50].

The American Society of Echocardiography published this statement in 2010 [7]:

“The use of ultrasound has developed over the last 50 years into an indispensable first-line test for the cardiac evaluation of symptomatic patients. The technologic miniaturization and improvement in trans- ducer technology, as well as the implementation of educational curricu- lum changes in residency training programs and specialty practice, have facilitated the integration of Focused cardiac ultrasound into practice by specialties such as emergency medicine. In the emergency department, focused cardiac ultrasound has become a fundamental tool to expedite the diagnostic evaluation of the patient at the bedside and to initiate emergent treatment and triage decisions by the emergency physician [30,31].”

They further posit that that the emergent evaluation of chest pain could be done with a focused echo exam, not the standard complete, but very time consuming exam [7]. They made it clear that a focused exam is much better in an emergent situation. They also pointed out the usefulness of small portable machines and made it clear that the “use of such machines substantially increases the detection of cardio- Vascular abnormalities over physical examination alone and increases diagnostic accuracy”.

The ASE paper references six papers which advocate the use of hand carried cardiac ultrasound devices to detect such abnormalities as LVH, LV dysfunction, cardiomegaly, Wall motion abnormality and clinically significant valvular regurgitation. Also noted was the usefulness of such devices in placing an emergency transvenous pacemaker and lo- cating the position of the pacemaker, plus being able to detect if perfo- ration of the RV had occurred.

An elegant, well controlled study of the evaluation of chest pain in the emergency department using an echo assisted physical exam was done by Sobczyk, Nycz and Zmudka in 2015 [22]. These authors excluded patients with acute STEMI, patients under 18, and patients whose body habitus was incompatible with accurate echo views. In their series of approximately 1100 patients, of those thought

to have non-STEMI, over 70% were found to have wall motion abnor- malities. Of those thought not to have an ACS at all, echo abnormali- ties were found in 55%. These abnormalities consisted of acute aortic dissection, changes in RV diameter and pressure indicating acute pulmonary embolus, newly discovered aortic stenosis, newly discov- ered acute valvular regurgitation, pleural effusion, pericardial effu- sion, cardiac tumor and other abnormalities. These investigators used a mnemonic device for organizing the exam, “A, B, C, D, E, F,” in which “A” stood for aorta, “B” stood for both chambers, “C” for car- diac wall motion, “D” for diameter (of RV versus LV), “E” For effusion, “F” for found other cause [27,28].

Pericardial effusion seen in parasternal long axis view.

Although CTA (CT angiography) and TEE (transesophageal echocar- diography) remain the gold standard for diagnosing aortic dissection, TTE is able to see the first 6 cm of the ascending aorta, and to view, from a suprasternal window, the aortic arch, first part of the descending aorta and the take off of the left subcla- vian, left common carotid and innominate artery and can often make or suggest the diagnosis in situations where patients do not have sufficient renal function for CTA exam or a TEE cannot be performed either be- cause the patient has not been fasting for the 6 h, has esophageal/dental problems, or no skilled operator is available. TTE at the bedside may pro- vide the examiner with a crucial clue (a dilated aortic root N 4 cm anda dissection flap) to set the patient on the proper Diagnostic pathway [10, 12].

In a 2014 article concerning the use of transthoracic echocardiogra- phy in the evaluation of chest pain [29], authors Aldwalk, Williams, Le Feuvre and Cowell pointed out that only about 1/3 of chest pains pre- senting to the emergency suite are actually cardiac in nature. They also pointed out the misleading and frustrating incidence of clinical symptoms which do not match the final and true diagnosis. Presented were three cases in which the symptoms and indeed ECG findings and even troponin did not match the final diagnosis. A 43 year old male was evaluated for chest pain and ST elevation with a normal troponin. He was found to have a dilated aortic root and an acute dissection. A sec- ond patient thought to have a prominent aortic arch on chest X-ray went through a CT scan which was negative for dissection, but on TTE was found to have a severe biventricular global impairment, elevated inflammatory markers of ESR and CRP and a final diagnosis of severe myocarditis. A third patient presented with chest pain and elevated tro- ponin. However, bedside TTE showed the RV to be severely dilated with

impaired function and RV pressure overloading. A visible intra-atrial thrombus was seen and the diagnosis of massive PE was made. In a sep- arate article by Olivieri et al. [20,21], the diagnosis of splenic rupture was made using ultrasound in a patient who complained of chest pain and was ruled out for STEMI and sent home, later to return with more chest pain [37].

Point of care echocardiography was performed in a series of 100 patients in a 2014 article in the Archive of Brazilian Cardiology. “In 28 patients, the focused echocardiography allowed to confirm the Initial diagnosis: 19 patients with heart failure, five with acute coronary syndrome, two with pulmonary embolism and two pa- tients with cardiac tamponade. In 17 patients, the echocardiography changed the diagnosis: ten with suspicious of heart failure, two with pulmonary embolism suspicious, two with hypotension without cause, one suspicious of acute coronary syndrome, one of cardiac tamponade and one of aortic dissection.” [34]. A 2011 study by Huish et al. found the sensitivity of transthoracic echocardiography to be 78% in the diagnosis of type A dissecting thoracic aneurysm. However when TTE was used as the initial evaluating study, patients were sent either to CT or given bedside transesophageal echo to con- firm the diagnosis, TTE worked well as an initial screening tool [17, 41]. Statistics for diagnosis of pulmonary embolism using TTE were not so encouraging in a 2001 study by Miniati, Monti, et al. In pa- tients with suspected PE, transthoracic echocardiography failed to identify some 50% of patients with angiographically proven PE. How- ever echocardiographic findings of RV strain, (such as dilated RV, RV:LV diameter ratio N 0.6 and sudden increase in pulmonary artery systolic pressure) support a diagnosis of PE [42]. (This was a 2001 study which may no longer be as accurate with the use of new tech- nology in Echocardiography machines.) We are able to see the right ventricle and right atrium very well with TTE; however we can only see the main pulmonary artery down to the bifurcation and the proximal right and left pulmonary artery. Clots beyond the bifur- cation and main pulmonary arteries are not likely to be seen with TTE. What is seen gives very useful information: acutely increased pulmonary artery systolic pressure, right ventricular dilatation, di- ameter ratio of RV to LV N 0.6, and Mcconnel’s sign (apex of heart contracts while the RV does not). Rather than directly visualizing the clot, these secondary signs suggest a diagnosis of PE. Regarding pneumonia, in a 30 patient study conducted in Tehran in 2015, the accuracy of ultrasound in diagnosing pneumonia was 100%, exceed- ing that of CT scan [43]. In a meta-analysis of over 6000 cases, re- searchers found that Lung ultrasound was a highly accurate and useful method for diagnosing pneumonia [44].

The accuracy of diagnosing pulmonary edema with ultrasound approaches 100%. The characteristic “lung rockets” caused by intraalveolar edema are hard to miss. Pneumothorax can also be rap- idly diagnosed by such parameters as absence of pleural sliding, lung point where pleural sliding stops, presence of the “bar code” sign on M-mode ultrasound, and the absence of “waves at the beach” pattern on M-mode.

From Lichtenstein and Meziere in a 2008 article in “Chest” (the jour- nal of the American Society of Chest Surgeons) came the following sta- tistics. These physicians did not use TTE to diagnose pulmonary embolus but used a combination of peripheral DVT + plus normal lung sliding and absence of B line artifact.

“Predominant A lines plus lung sliding indicatED asthma (n = 34) or COPD (n = 49) with 89% sensitivity and 97% specificity. Multiple ante- rior diffuse B lines with lung sliding indicated pulmonary edema (n = 64) with 97% sensitivity and 95% specificity. A normal anterior profile plus deep venous thrombosis indicated pulmonary embolism (n = 21) with 81% sensitivity and 99% specificity. Anterior absent lung sliding plus A lines plus Lung point indicated pneumothorax (n = 9) with 81% sensitivity and 100% specificity [2]. Anterior alveolar consolidations, an- terior diffuse B lines with abolished lung sliding, anterior asymmetric interstitial patterns, posterior consolidations or effusions without

Table 1

Sensitivity and specificity of echocardiography in the evaluation of chest pain.

Condition	Sensitivity	Specificity
Asthma and COPD [45]	89.00%	97.00%
Infectious endocarditis (children) [46]	86.00%
Infectious endocarditis (adults) [47]	34.20%	99.00%
Pericardial effusion [15]	95.00%	91.00%
Pericardial tamponade [13,48]	85.00%	92.00%
Pericarditis (constrictive) [49]	87.00%	91.00%
Pneumonia [43]	89.00%	94.00%
Pneumothorax [45]	81.00%	100.00%
Pulmonary embolus (direct visual) [50,18]	50.00%
Pulmonary embolus (indirect signs of) [18]	93.00%	81.00%
Pulmonary embolus:DVT + Neg lung US [45]	81.00%	99.00%
Pulmonary edema [45]	97.00%	95.00%
Thoracic aortic aneurysm A [25,35,41] Wall motion abnormality (CAD) [16]	78.00% 90-95%	80.00%

anterior diffuse B lines indicated pneumonia (n = 83) with 89% sensi- tivity and 94% specificity. The use of these profiles would have provided correct diagnoses in 90.5% of cases.” [45].

See Table 1 for a summary of the sensitivities and specificities of TTE for conditions presenting with chest pain.

1. The role of ECG in diagnosing chest pain

Although ECG interpretation has been the standard of care in the initial evaluation of chest pain, ECG itself is not infallible in the diagnosis of STEMI, pericardial effusion, tamponade, aortic dissec- tion, NSTEMI, pericarditis, pneumonia or pulmonary embolus. ECG of an acute inferior wall MI with ST elevation in leads II, III, and AVF is indistinguishable from ST elevation caused by a dissecting thoracic aneurysm ripping past the right coronary artery orifice. In a 2000 study of 1003 patients with chest pain, “The admission ECG has been confirmed as a poor sensitivity test for the diagnosis of AMI (49%), with a positive predictive value considered only satisfactory (79%)” [39]. “Important diagnostic tests when evaluating for acute coronary syndrome include the 12-lead ECG, serum markers of myo- cardial damage, and cardiac testing with Stress testing or nuclear im- aging. ECG findings that most strongly suggest MI are ST segment elevation, Q waves, and a conduction defect, especially if such find- ings are new compared with a previous ECG. New T-wave inversion also increases the likelihood of MI [7,9]. However, none of these findings is sensitive enough that its absence can exclude MI.” [40]. Despite these limitations, ECG remains the best tool we have for the initial evaluation of potentially life threatening chest pain.

1. Proposed method of evaluation of chest pain

The following parameters are assessed: 1) ejection fraction;

2) aortic valve excursion as an index of systolic LV function; 3) pres- ence or absence of pericardial effusion and tamponade; 4) presence or absence of dissection flap in the aortic root; 5) presence or absence of left ventricular wall motion abnormality; 6) presence or absence of acute regurgitation across the mitral or aortic valve;

7) presence or absence of pulmonary alveolar edema; 8) questions about symptoms including nausea, epigastric burning, clinical symp- toms of anxiety or panic states, and pain exacerbated by moving the thorax or on pressure to the thorax; 9) the variation in size of the inferior vena cava with respiration.

The usual ECG, cardiac markers, d-dimer and X-ray for evaluating chest pain are also ordered on initial contact at the direction of the emergency physician.

Practitioners of the exam use a checklist, see attachment [36].

Practitioners record the time the exam took and the initial diagnostic impression formed before looking at lab work or X-rays.

1. Initial study: ease of use and teaching the exam to emergency medicine residents

Advanced echocardiographic skills are not required to successfully perform and interpret the Chest CASE exam [14,19,23,24]. An emergen- cy physician with basic ultrasound skills should be able to rapidly and accurately use this exam with only a brief focused training session. The echocardiographic skills required to complete the exam include: obtaining 4 views of the heart (parasternal long axis, Parasternal short axis, subxiphoid and apical four chamber), the suprasternal view of the aortic arch, and basic pulmonary views; using M-mode and B- mode; identifying A-lines and B-lines on lung images; and recognizing pneumothorax, pleural effusion, and pericardial effusions [6,8,26].

To verify the hypothesis that this is an easy exam to learn and per- form, the ability of novice ultrasonographers to learn and perform this exam in a timely fashion will be assessed. Senior emergency medicine residents (PGY-2 and above), and emergency medicine attending physicians without advanced ultrasound skills will be recruited to participate in this study.

They will be tested on their ability to perform cardiac ultrasonography pre-intervention to establish baseline skills. They will then be given a two-hour didactic lecture on the techniques of performing this exam, followed by a two-hour hands-on echocardiography lab to practice the skills.

Learners will be assessed post course on their ability to perform the exam accurately and in a timely fashion through both multiple choice questions and hands-on demonstration. They will be reassessed at six weeks to ensure retention of skills.

Inclusion criteria: senior emergency medicine residents (PGY-2 and above) and emergency medicine attending physicians at Arnot Ogden Medical Center.

Exclusion criteria: advanced sonographic training.

1. Follow-up study: utility of chest CASE exam in clinical practice

Data will be collected over a period of six months by dedicated research-ultrasound residents who have been judged as proficient in this exam by the study authors.

The exam will be performed on all patients with chest pain who meet the Inclusion/exclusion criteria during periods in which a study- trained resident is available. Informed consent will be obtained from the patient. The resident will collect all of the clinical information about the patient on a form with a unique identifying number. Clinical information includes the echo screening exam plus observation of chest wall tenderness or pain on motion, whether or not there are symptoms of indigestion, or if the patient admits to emotional upset or anxiety. Other than age, gender and relevant past medical history, information will be de-identified. The ultrasound images will also be labeled by the performing resident with the identifying number and no additional identifying information will be kept with the images. The treating physician will not be aware of the initial ultrasound results. After the treating physician has completed his evaluation (not including any ultrasound exam) he can discuss the ultrasound results with the researcher and determine if changes to the assessment of the patient and clinical plan should be made.

Images will be collected and stored electronically The studies collected would be preserved in the hospital’s DICOMM imaging system and all would be reviewed by a supervising individual who is board certified in Emergency Medicine and Echocardiography or who is a registered Radiologist or Cardiologist.

The following data will be tracked:

Diagnosis based on ultrasound exam

Confidence of performing physician of this diagnosis

Accuracy of ultrasound images estimated by performing physician

time to perform exam

Diagnosis based on standard evaluation by treating physician (unaware of ultrasound results)

Confidence of treating physician of this diagnosis

After learning of the ultrasound results, are you revising your diagnosis and plan?

Time at which treating physician is ready to disposition patient

Time at which disposition of patient is made.

Diagnosis based on expert review

Confidence of expert reviewer of diagnosis

Accuracy of ultrasound images by expert reviewer

Analysis will look separately at patients in whom only limited study data could be obtained for reasons including inability to assume necessary

position for exam or poor sonographic data due to body habitus or emphysematous lungs.

Inclusion criteria: patients 18 years or older presenting to Arnot Ogden Medical Center emergency department with chest pain.

Exclusion criteria: patient deemed too critically ill to undergo study by the treating emergency physician. All patients with chest pain who meet inclusion criteria will be evaluated with chest CASE exam. All patients will be analyzed as a group. A subgroup of those patients in whom the examination was successfully completed (due to appropriate body habitus and ability to assume required po- sitioning) will also be analyzed.

1. Summary

Point of care Echocardiographic examination of the thorax for chest pain has become an achievable goal due to the advent of small, portable echo systems, more widespread knowledge of basic echo views and measurements, and encouraging data from past studies indicating that this is the correct direction for clinical evaluation by Emergency Medicine attending physicians and residents. This article proposes a ten-minute evaluation which includes exam of the heart, lungs, ascend- ing aorta and aortic arch, plus clinical questions about GI symptoms, emotional symptoms and the presence or absence of pain during thoracic palpation or movement. An exam conducted in such a manner, is much more likely to lead to the correct diagnosis, uncover causes of chest pain which are non-cardiac, and unmask potentially lethal conditions such as massive PE or aortic dissection. A need exists to conduct a large scale study to verify the usefulness of such an exam and to determine the feasibility of teaching this exam to Emergency Medicine providers.

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