Intrathoracic space competition from heart enlargement and pulmonary edema (complications of CHF) that compress airway construction and bronchioles. Bronchial obstruction secondary to intraluminal edema. Bronchial mucosa edema. Diagnosis
The diagnosis of cardiac asthma is accomplished through workup of congestive heart failure, complete with:

Evaluation of current symptoms with specific consideration of chronological progression or worsening. Past Medical History screen with consideration for conditions that predispose to heart failure, such as prior heart attack, history of coronary revascularization, high blood pressure, or diabetes (heart). Physical Exam with emphasis on listening for abnormalities of heart sound, abnormalities of lung sound, or presence of increased fluid retention in neck or in extremities. Laboratory Evaluation with specific interest in B-type natriuretic peptide levels. Electrocardiography to evaluate for irregularities in heart rhythm. Chest Radiograph to evaluate for presence of lung congestion or increased heart size. Echocardiography to evaluate heart function. Echocardiography is the preferred choice for diagnosis of heart failure in patients.As well as evaluation of lung function via:

Pulmonary function testing (PFT) complete with bronchoprovocation testing. PFTs represent the preferred method for evaluating for bronchial asthma. Management
Treatment of asthma symptoms in CHF patients is directed towards optimizing the patients cardiovascular status and correcting potential oxygen deficit. Current recommendations in acute asthma symptoms are utilization of diuretics such as furosemide, venodilators such as nitroglycerin, and morphine. The initial strategy should focus on decreasing patient fluid retention with diuretic therapy, thereby decreasing cardiac preload and overall fluid load in pulmonary circuit (pulmonary congestion).
Cardiac asthma is the medical condition of intermittent wheezing, coughing, and shortness of breath that is associated with underlying congestive heart failure (CHF). Symptoms of cardiac asthma are related to the hearts inability to effectively and efficiently pump blood in a CHF patient. This can lead to accumulation of fluid in and around the lungs (pulmonary congestion), disrupting the lungs ability to oxygenate blood.Cardiac asthma carries similar symptoms to bronchial asthma, but is differentiated by lacking inflammatory origin. Because of the similarity in symptoms, diagnosis of cardiac versus bronchial asthma relies on full cardiac workup and pulmonary function testing.Treatment is centered on improving cardiac function, maintaining blood oxygen saturation levels, and stabilizing total body water volume and distribution. Signs and symptoms
The most common findings of cardiac asthma are the presence of wheeze, cough, or shortness of breath (predominantly occurring at night or when laying down) in a patient that possesses signs of congestive heart failure.Additional findings consist of production of frothy or watery sputum and presence of water in the lungs that can be heard via stethoscope. In severe cases, a patient can experience multiple night time episodes of breathlessness, changes in skin coloration, and episodes of bloody sputum. Pathophysiology
The underlying causes for cardiac asthma stem from the eventual back up of fluid into the pulmonary vasculature as a result of the hearts, particularly left sided, inability to effectively and efficiently pump blood.