Rhythm Nation - Case #6 - Answer

Thanks for the responses! Here is the answer and case discussion

EKG Interpretation –

Rate – 70-80s

Rhythm – no discernable P waves. Regular rhythm. No fusion or capture beats to suggest AIVR. Thus, the most likely diagnosis is an Accelerated Junctional Rhythm

Axis – Extreme Left Axis deviation with a QRS axis of around -60

Intervals – no PR interval, Prolonged QRS interval in the 140ms range. QT looks relatively normal but if you calculate the QTC it is slightly prolonged in the 480ms range. The precordial leads show a RBBB pattern with an RSR in V2, monophasic R in V1 and poor R wave progression.

ST segments – 0.5mm ST depressions in I and AVL. T waves inverted I, AVL, V1-V5.

Other notes – Q waves inferiorly, LVH w/ AVL > 11mm

Putting it all together, our CXR shows cardiomegaly as well as parenchymal lung disease which could be CHF but does not look typical of interstitial fluid. Our bedside echocardiogram was concerning for signs of right heart strain. Our CTA was negative for PE but showed signs of interstitial lung disease. Thus our final diagnosis was a combination of CHF exacerbation with ILD causing dyspnea. These help to explain the RBBB as secondary to myocardial stretching from chronic RV pressure overload.

Signs of RV pressure overload in the setting of the dyspneic patient could be due to a pulmonary embolism or acute MI, but it could also be attributed to chronic causes of right heart strain. These include idiopathic or familial pulmonary hypertension, connective tissue diseases, drugs, toxins, hemoglobinopathies, myeloproliferative disorders, congenital shunts, left sided heart failure, COPD, insterstitial lung disease and OSA. Many of these can be diagnosed based on the history and physical which can prompt specific further testing. In most of these cases, the further testing is usually blood tests which, while they can be painful, do not have significant morbidity.

However testing for pulmonary embolism can cause significant morbidity especially if done repeatedly. First, many times the alternative diagnosis is right heart failure due to pulmonary hypertension of another cause. The dye load that is given in order to perform the angiogram, while a small amount of fluid, can tip the balance and put an already dyspneic patient into acute pulmonary edema. Second, the injection of contrast dye should always be considered a risk for an allergic or anaphylactic response which can lead to intubation or even death. Third, in patients who are presented to the ED frequently for chronic dyspnea they may be subjected to multiple CT scans which can be a significant radiation dose. While these patients may be chronically sick and have diminished life expectancy, subjecting them to avoidable CT scans should not be taken lightly. These additional diagnostic tests in a patient with abnormal lungs can lead to false positives and inappropriate anticoagulation which comes with its own additional morbidity and mortality. Furthermore, these additional hospitalizations come with their own morbidity as well as additional costs for the patient as well as the healthcare system.

In these patients with multiple complex medical problems and multiple presentations to the emergency department, we should always be reviewing the medical record and recent diagnostic test to evaluate the need for further workup. If recent CT angiograms were negative and the patient’s presentation is unchanged, then it may be more prudent to pursue an exacerbation of their chronic lung disease or heart failure as a cause of the recurrent dyspnea.

In addition, we can look at some parameters of the echocardiogram to suggest whether the right ventricular strain is acute or chronic. These echocardiographic findings can be subtle and require specific measurements, thus a cardiology consult may be in order. However, since an echocardiogram is a benign test, as long as the patient is hemodynamically stable the additional delay to the final diagnosis may be acceptable.

The echocardiogram can help to identify features pointing to the cause of pulmonary hypertension. An intracardiac shunt or left heart failure can be easily visualized. The appearance of the myocardium can suggest amyloidosis, hemochromatosis or other restrictive heart disease. Dilated esophageal or portal veins can suggest portal hypertension or nodules within the posterior myocardial wall can suggest sarcoidosis.

The echocardiogram can also help note the degree and chronicity of heart failure. In the setting of acute right heart strain, the ventricle does not have time to remodel. The right ventricle may be dilated, but other parameters that change in chronic heart failure may be preserved. The right ventricular wall diameter should be < 5mm. A thicker wall suggests that the ventricle has had time to adapt to chronically elevated pressures.

Another measurement that can help differentiate acute from chronic heart failure is the pulmonary artery pressure. This can be done using the tricuspid regurgitation jet or measurement of the pulmonary outflow tract. A normal pressure is < 25-35mmHg. However, patients with pulmonary hypertension can have pressures upwards of 60mmHg. In the setting of an acute PE, the pressures are expected to double from baseline to approximately 40mmHg in patients with no underlying pulmonary hypertension. If the information from a prior echo is available and the repeat measurement is not significantly different an acute PE becomes less likely. If no prior echo is available it becomes more difficult to interpret the pulmonary arterial pressure.

While pulmonary embolus is one of the can’t miss diagnoses in the emergency department, its presentation is so variable that it is a diagnosis that is often missed. Because of this, we are often hypervigilant in making sure to rule out this diagnosis when we do think about it. In patients with pulmonary fibrosis who may be chronically short of breath and have evidence of right heart strain on echo, pulmonary embolism is likely the first thing we think about, especially if the initial history is limited. However, there are certain specific findings that we can look for to evaluate if this patient has a new pulmonary embolus on top of their chronic disease. By remembering these findings we may not always be able to avoid the CTA, but in certain specific cases we can attribute the echo findings to chronic pulmonary hypertension and rationalize not doing the CT angiogram. This however, is the exception to the rule and should not be relied upon frequently.

What do you think? Would you ever use echo findings to help rationalize not getting the CTA?

References:

Simonneau G. Proposal for a new diagnostic classification: The 2003 Venice classification. 3rd world symposium on pulmonary arterial hypertension, Venice, 23–25 June 2003

Hatano S, Strasser T. World Health Organisation 1975 primary pulmonary hypertension. Geneva: WHO; 1975

Groves, B. M., Brundage, B. H., Elliott, C. G., et al.: Pulmonary hypertension associated with hepatic cirrhosis. In Fishman, A. P. (ed.): The Pulmonary Circulation: Normal and Abnormal. Philadelphia, University of Pennsylvania Press, 1990, pp. 359–369

Nath J, Demarco T, Hourigan L, Heidenreich PA, Foster E. Correlation between right ventricular indices and clinical improvement in epoprostenol treated pulmonary hypertension patients. Echocardiography. 2005 May;22(5):374-9

Clinical Cardiology: New Frontiers – Acute Pulmonary Embolism: Part I – Epidemiology, Pathophysiology, and Diagnosis. Samuel Z. Goldhaber, MD, C. Gregory Elliott, MD; Circulation 2003; 108:2726-2729