Case In Point: Does this woman with cough and dyspnea really have CHF?

The authors describe a patient who appeared to have congestive heart failure (CHF), but the actual diagnosis was mitral stenosis.

The case

A 47-year-old African American woman presented to the hospital after a 5-day history of cough and shortness of breath. The patient also described worsening cough with yellow sputum production over that same time but denied any fevers, chills, nausea, vomiting, abdominal pain, and urinary symptoms. Her condition began to rapidly deteriorate on arrival to the emergency department (ED).

The patient's medical history included peptic ulcer disease with ulcer perforation in 1994. Her surgical history was significant for an endoscopic gastroduodenoscopy to repair gastric perforation. She also underwent a cesarean section and hysterectomy secondary to fibroids in the distant past. A Baker cyst drainage was performed 1 week before admission.

Her only medication was aspirin, 81 mg daily. She had no known drug allergies. The patient had a 20-pack-year smoking history and was a former alcoholic, having stopped drinking 11 years ago. She denied previous illicit or recreational drug use. She was employed at a printing company with no known occupational exposures, and she had no recent sick contacts. Her family history was significant for a mother and brother with diabetes mellitus.

Her vital signs at admission were temperature of 36.3°C (97.3°F), heart rate of 109 beats per minute, respiration rate of 32 breaths per minute, and blood pressure of 103/54 mm Hg. Her oxygen saturation was 98% on 100% non-rebreather mask. She was sitting upright in bed and was tachypneic, but she was alert and oriented to person, place, and time. Her mucous membranes were moist, turbinates were not erythematous, and pharynx showed no inflammation. There was mild jugular venous distention and no enlarged thyroid gland.

The heart rate was tachycardic and the point of maximal intensity was not displaced. No murmurs were auscultated on initial examination. The lungs revealed bilateral rales extending throughout the inferior two thirds of the lungs. There were no appreciable rhonchi or wheezes. Abdominal findings as well as findings from her neurologic examination were unremarkable. No cyanosis, clubbing, or edema was seen in her extremities.

The patient's baseline complete blood cell count showed a white blood cell count of 8500/µL, hemoglobin level of 13.6 mg/dL, hematocrit value of 41.1%, and platelet count of 312,000/µL. Basic metabolic profile and serum coagulation test results were within normal limits. Total creatine phosphokinase level was 206 U/L with an MB fraction of 2.2 and an initial troponin level of less than 0.03 ng/mL. Her brain natriuretic peptide (BNP) level was 770 pg/mL. Arterial blood gas analysis showed a pH of 7.42, PCO₂ of 35 mm Hg, and PaO₂ of 48 mm Hg.

An ECG revealed sinus tachycardia at a rate of 127 beats per minute. There was a right axis deviation and poor R-wave progression. Left atrial enlargement was present, and there were occasional premature atrial contractions. The chest radiograph showed bilaterally increased interstitial markings, small bilateral pleural effusions, prominent pulmonary vasculature, and a normal cardiac silhouette (Figure).

While in the ED, the patient's condition began to deteriorate. She became severely dyspneic and tachypneic, with a respiration rate of 40 breaths per minute. Her oxygen saturation fell to 88% on 100% non-rebreather mask.

The initial diagnosis was acute CHF with a volume-overloaded state, and the patient was treated with morphine, 2 mg IV, and furosemide, 40 mg IV, and a nitroglycerin infusion was started. Despite medical therapy, her condition continued to worsen, and emergent 2-dimensional transthoracic echocardiography was performed. This showed a thickened mitral valve with a mean gradient of 18 (severe mitral stenosis greater than 16), left atrial enlargement with a chamber size of 6.2 cm (normal, 1.9 to 4.0 cm), and an ejection fraction of 60%. These values were consistent with severe mitral stenosis.

The patient was transferred to the ICU. Nitrates were discontinued, and an esmolol infusion was started to slow the heart rate and allow for better diastolic filling time. Furosemide and aspirin were continued, as well as morphine as needed. While in the medical ICU, the patient's condition vastly improved, with a respiration rate of 16 breaths per minute and an oxygen saturation of 100% on 2 L of oxygen via nasal cannula.

Further history was ascertained from the patient, and she denied any history of rheumatic heart disease. The next hospital day, the patient was switched to oral ß-blocker therapy and transferred to a telemetry floor. Her condition continued to improve and she was discharged, with referral to a cardiovascular surgeon to discuss options of mitral valve replacement or valvuloplasty.

Discussion

Mitral stenosis is defined as the thickening and restriction of the mitral valve leaflets. Normal blood flow between the left atrium and ventricle is impeded and, if left untreated, leads to elevated left atrial pressure, left atrial enlargement, increased pulmonary pressures, and eventual right-sided heart failure. Although a number of underlying entities are known to cause mitral stenosis, most cases are a consequence of rheumatic fever. The potential lethal complications of this disease have led to the development of a number of different treatment options.

The major cause of mitral stenosis remains rheumatic fever, an inflammatory disease that can develop after a streptococcal infection. Other, less common causes of mitral stenosis are infective endocarditis, mitral calcification, systemic lupus erythematosus, rheumatoid arthritis, carcinoid heart disease, and congenital abnormalities.

Most definitively described by Bouillaud in 1835, rheumatic fever was the leading cause of death in school-age children until the 1930s. The introduction of antibiotics dramatically decreased the overall mortality. Several more recent studies, however, have identified sustained rheumatic involvement in mitral valve disease.¹

The pathologic effects of rheumatic fever on the mitral leaflets can include fusion of the mitral leaflets; thickening, fibrosis, and calcification of the leaflets; and thickening, fusion, and shortening of the chordae tendinae.² The acute symptoms of rheumatic fever usually subside in weeks or months, with the valvular manifestations appearing 10 to 30 years later; yet, only 50% to 70% of patients report a history of rheumatic fever.^1,3

The most common clinical presentation of mitral stenosis is dyspnea resulting from vascular congestion and interstitial edema. As valve stenosis progresses, the patient's dyspnea on exertion worsens and orthopnea may develop. The risk of thromboembolism arises with the development of left atrial enlargement resulting from increased atrial pressures. This can lead to atrial fibrillation with clot formation within the left atrial appendage. In addition, there is an increased risk of thrombus formation on the damaged valves, with associated systemic embolization.

Right-sided heart failure is the result of chronic pulmonary hypertension. Right atrial and ventricular enlargement, tricuspid regurgitation, and the sequelae of right heart failure (jugular venous distention, lower extremity edema, hepatomegaly) may all occur. Hemoptysis resulting from elevated pulmonary pressures is also common in patients with mitral stenosis.⁴

A thorough cardiac examination can be diagnostic of mitral stenosis. The characteristic "opening snap" is the result of ventricular relaxation and elevated atrial pressures forcing the mitral valve leaflets open. As stenosis progresses, left atrial pressure further increases, and the opening snap occurs earlier after S₂. These findings may be less apparent in patients under acute distress, as in our case, and both tachycardia and tachypnea may hinder diagnosis by physical examination.

Blood flow across the mitral valve is translated into a low-pitched, diastolic rumble heard best at the apex. The duration of the murmur, rather than the intensity, correlates to the severity of stenosis. Thus, a significantly advanced mitral stenosis murmur may be holodiastolic and diminished as a result of reduced volume of blood flow through the valve.

The initial clinical presentation of the patient described here appeared consistent with CHF. An acute onset of symptoms, along with the findings of mild jugular venous distention and rales on lung auscultation, led to a strong suspicion for biventricular heart failure. Radiographic findings as well as an elevated BNP level supported our working diagnosis; the bedside transthoracic echocardiogram revealed severe mitral stenosis as the true cause of the patient's symptoms and presentation.

There are a number of accepted treatment options for mitral stenosis. Medical therapies are of limited value, since they provide only transient improvement in symptoms. Diuretics may be used in patients with pulmonary edema caused by back flow of pressure from the stenotic mitral valve. Advanced mitral stenosis with right-sided heart failure and lower extremity edema may also be an indication for the use of diuretics.

Digoxin is limited primarily to patients with atrial fibrillation and a rapid ventricular response. In symptomatic, tachycardic patients, ß-blockers can help by slowing the heart rate and increasing diastolic filling time, thereby allowing better blood flow across the valve and augmenting cardiac output.⁵

The definitive treatment that reduces mortality in patients with mitral stenosis is surgery. Closed and open commissurotomies, percutaneous balloon valvotomy, and mitral valve replacement are all feasible options. Closed commissurotomy is performed via open thoracotomy. A dilator is placed through the atrium or ventricle, and the valve is dilated without direct visualization. Absolute contraindications to the procedure are the presence of left atrial thrombus or severe mitral regurgitation.

Long-term results from closed commissurotomy were observed in a study from India of 3724 patients, most of whom were identified as New York Heart Association (NYHA) class IV.⁶ Inpatient hospital mortality was 1.5%, and symptomatic improvement occurred in 86% of patients at 15-year follow-up. Restenosis occurred at a rate of 4.2 to 11.4 per 1000 patients per year between the 5th and 15th years of follow-up.⁶

Open commissurotomy via median sternotomy uses cardiopul-monary bypass in accomplishing mobilization of the mitral valve.⁷ Direct visualization of the valve allows better inspection of the defect, removal of calcium deposits, mobility of restricted chordae tendinae, and removal of any atrial thrombus. A number of studies have displayed favorable outcomes in patients who have undergone open commissurotomy.^8-13 Perioperative mortality is less than 1%; the rate of restenosis requiring intervention at 5-year follow-up is 6.6%.^8-13

Percutaneous balloon valvotomy, developed by Inoue in 1984 and Lock in 1985, is another option for some patients. During cardiac catheterization, a transseptal puncture is used to access the mitral valve. Inflation and rapid deflation of the balloon across the valve increases the mitral orifice. The outcome data for balloon valvotomy are similar to those for open commissurotomy, with comparable initial improvement of valve area and low rates of restenosis. With similar outcomes, percutaneous balloon valvotomy may be favored over open commissurotomy because of the increased hospital stay and increased morbidity associated with median sternotomy.

Valve replacement is reserved for patients with poor valve morphology who are not candidates for open commissurotomy or balloon valvotomy. The Veterans Affairs Cooperative Study on Valvular Heart Disease showed the all-cause mortality at 15 years to be 81% for mechanical valves and 79% for bioprosthetic valves.^6,11

In general, bioprosthetic valves are preferred in patients older than 70 years and in those who are unable to take warfarin. Mechanical valves are generally used in younger patients, patients with prosthetic valves already in place, and patients with end-stage renal disease who are on hemodialysis. Compared with other procedures, valve replacement carries higher perioperative mortality relative to the patient's age and overall status; mortality is 5% in young healthy persons, 10% to 20% in older persons, and up to 25% in those with NYHA class IV disease.¹⁰

In summary, the recognition of mitral stenosis requires an accurate history, directed physical examination, and clinical awareness of the valvular condition. Medical therapy relieves symptoms, but surgical options offer definitive treatments for patients. Percutaneous balloon valvotomy is the preferred surgical procedure, and it is associated with low rates of restenosis and favorable long-term outcomes.

References:

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