“Symptom Driven” Transthoracic Echocardiography: utility of modern echo techniques

When I first started out in outpatient cardiology, I had no money to hire an echo technician and I ended up doing my own echo. As a result, I became very good with echo scanning technique. About ten years ago, my assistant asked me: “Doctor, do these echoes actually make any difference in the patient care? Is it such a big deal if Mr. W has mild mitral regurgitation?”

I started wondering to myself: beside me getting paid, do these echoes make any difference?

I come to realize that echo can make a difference if echocardiographic diagnosis can refine therapy, either medical or invasive, and that having echo-guided therapy improves outcome.

However I also come to realize that the usual way of doing echo makes little difference. Sure, finding that LVEF is low helps put the patient on ACEI and beta-blocker, which saves lives. Finding severe valve diseases help steer patients live-saving valve surgery. But these scenarios do not apply to most of the patients.

Because I do own echoes, I know the clinical questions of my patients well. I started focusing on using echo to answer the relevant clinical question. Example includes: (1) is the chest pain or dyspnea cardiac in origin? (2) What is the risk of the patients having a stroke and MI? do I need to adjust his/her medications? (3) is the patient fluid overload or dry? (4) why is the patient hypotensive?

Therefore, I started expanding echo technique beyond the traditional confine described in the textbook. I learned this from Dr. Itzhak Kronzon, who used to be at NYU. I had the opportunity to attend his weekly echo rounds and learned that to be a good echocardiographer you need to be a good clinician and knows the disease. He would grill the trainees hard on pathophysiology of various disorders and signs of physical exam. Therefore the first thing I did was to really learn echocardiography and its relationship with physical exam and pathophysiology. The next thing I learned was that he is not restricted to what was in the textbook and he was doing carotid intimal thickness on all his patients. I also followed his example and reviewed the literature deeply.

Shortly after, I became intrigued by the expanded role of ultrasound in emergency medicine. Because I had full access of the ultrasound machine and I was using my ultrasound probe on every single patient on almost every single visit, I practiced and learned new ultrasound technique as performed in critical care and emergency medicine on every single patient I saw. I also correlated this with my physical exam.

Using these deeper insights and expanding echo technique beyond traditional boundary, I now can confidently answer: “Yes, echocardiography can make a difference if you are willing to go beyond the traditional boundary to really address the patient’s clinical question.”

Interesting, quite recently, the JAMA paper came out describing the futility of screening echo (Lindekleiv H et al. Echocardiographic Screening of the General Population and Long-term Survival: A Randomized Clinical Study. JAMA Intern Med. 2013;173(17):1592-1598. doi:10.1001/jamainternmed.2013.8412.) During 15 follow-up years, 880 persons (26.9%) in the screening group and 989 persons (27.6%) in the control group died (hazard ratio, 0.97; 95% CI, 0.89-1.06). No significant differences between the groups were observed in the secondary outcome measures (sudden death, mortality from any heart disease, or incidence of fatal and nonfatal myocardial infarction and stroke).

The reason why I think these screening echoes are useless is that these echoes were not done to answer a clinical question; and that the findings were not used clinically to refine the therapeutics. These echoes were still done using the traditional approach. It forces the clinician to view the heart through the lens of traditional echo diagnostic category: LVEF; LA size, etc.

Whereas the expanded echo approach takes the patient clinical question, and seeks echocardiographic and ultrasound clue to refine the differential diagnosis or risk stratification.

For example, the other day I saw a 80 year old man with dyspnea. I made a differential diagnosis: (1) lung related, (2) cardiac related, (3) hematological. In each category, I looked for echo sign. I would use a high frequency probe to look at the lung to see if he has sign of B-lines unilaterally (=pneumonia) or bilaterally (CHF or ARDS) (see this link for how it is done); I would looked at the pulmonic artery wave form to calculate the PCWP using the PR end diastolic pressure; the slope of the pulse wave pulmonary artery ejection jet gives clues to pulmonic systolic function. I would use high frequency probe to look at JVP; IVC size would be M-moded, and SVC and hepatic vein pulsed to look for S/D  dominance– all of these help calculating RA pressure. Conventional E/e’ of mitral and tricuspid inflow would be used to calculate LA and RA pressure and to assess diastolic function (see RA pressure measurement paper in JASE). Then the LVEF is examined. If I have time, I would perform global and regional LV strains to decipher hidden decreased in LV contractility and looks for clues of CAD as seen in focal changes in LV wall strain. In addition, the smoothness/ calcification and the reflectiveness (calibrated integrated backscatter values) of the myocardial texture gives clue to renal failure, aging and other biochemical/ pathophysiological changes. Carotid intimal medial thickness gives clue of the degree of CAD (see this paper, for example.)

As you can see, if we let the clinical question drives the echo approach, the utility of the technique vastly expands and we will have refined the probability of our differential diagnoses significantly. With plenty of practice, the above expanded echo exam can be done with high time efficiency. Unfortunately, most clinicians lost their echo skills and cannot take advantage of many of these expanded techniques.

We use the high-end GE Vivid S6 ultrasound, which is highly cost effective for us. It is a joy to use.  Above images are example taken from the machine: it takes less than 1 minute to obtain this image using the automated feature. We made a decision not to use 3D imaging in our daily work because of limited outcome data, time required, and the much higher machine cost in the environment of diminishing reimbursement. While the data show that LVEF by 3D is superior to that of 2D (see review article by Wood et al 2013), this is only true if the image is of sufficient quality, and this is often not the case in real day to day practice. In more recent literature (e.g., see Altman et al), 3D quantitative measurement (e.g. 3D strain) is not  superior to 2D measurements (e.g. 2D Global longitudinal strain).

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