What is cardiac asthma or cardiac cough?
For centuries, it has been known that cardiac diseases can cause dyspnea, cough and even expiratory wheeze, as we can see in asthmatic patients. The term “Cardiac Asthma” has been used very loosely for decades to describe this constellation of symptoms, but it refers explicitly to chronic cough and expiratory wheeze, which mimics the symptoms of bronchial asthma.
In 1833, the term “Cardiac Asthma” was first coined by James Hope, an English physician, in the medical literature. 20 years later, the infamous Irish physician, William Stokes, established the term as a medical diagnosis in medicine. James Hope is considered the first “Modern Cardiologist” in history and is well known for many discoveries in Cardiology. His theory was that the diseases of the left ventricle increase the blood volume in the heart, which acts as an obstacle to the blood flow from the left atrium towards the left ventricle. This obstruction then transfers backward towards the pulmonary vasculature, resulting in pulmonary congestion, edema, cough, wheeze and dyspnea. In 1897, William Osler defined the entity as follows,
Although we do not use the term “Cardiac Asthma” as frequently, it is very informative and enlightening to review the historical papers and appreciate the accuracy of their knowledge about the pathophysiology of the diseases without having access to the advanced investigative technology, we have readily available today. One of these papers is an elegant article published in 1951 by, Tinsley Harrison, the author of Harrison’s textbook of internal medicine. In this article, he has extensively elaborated on the definition of cardiac asthma and the pathophysiology of dyspnea in various cardiac diseases. Here is the last paragraph of the article,
Cardiac asthma (cardiac cough) and heart failure:
In Chronic Heart Failure (HF), as patients gradually and subconsciously withdraw from physical activity, they are less likely to report (or appreciate) the symptoms of Heart Failure. Therefore, a detailed history taking is critical for accurate diagnosis, and it is crucial to precisely ask them about their current activity level compared to a past point in time. For example, if they had been climbing one flight of stairs readily one year or month ago, can they do the same without difficulty.
Initially, dyspnea may only present with physical activity and not at rest and they may only complain of fatigue, lethargy and anorexia. Peripheral bilateral edema may present intermittently, and as the disease progresses, edema becomes more resilient to simple remedies and less likely to resolve spontaneously, without therapy.
As chronic HF progresses slowly, the pulmonary vascular bed adjusts to the chronic state of “volume overload” over time. This adjustment leads to less or no fluid accumulation in the alveoli, despite increasing total lung water and high filling pressures but it certainly reduces overall pulmonary vascular reserve, which leads to significant “exertional dyspnea”.
As the disease progresses and intracardiac pressures rise further, pulmonary vasculature can not cope any further and fluid accumulates in the alveoli, resulting in dyspnea and cough, a natural body response to clear the fluid. Initially, this happens exclusively at night, in a recumbent position. This is due to the “nocturnal reabsorption of fluid in the dependent body regions“, increasing venous return to the right ventricle, leading to “paroxysmal nocturnal dyspnea”. Patients awake from sleep with cough and dyspnea. Like asthma patients, they might have squeaky breathing sounds (wheeze) and may seek fresh air at the windows. More severe cases present with pulmonary congestion (edema), more severe cough, profuse cold sweats and rales (widespread bubbling sounds on respiratory auscultation). In 1915, Sir Thomas Allbutt, an English physician, has described a patient with pulmonary edema as follow,
Despite this well-established knowledge, accumulated over decades, still, we can see occasional missed cases of “cardiac asthma” for “bronchial asthma” or other respiratory diseases. For apparent reasons, It is essential to differentiate respiratory causes of cough and wheeze from secondary causes, mainly heart failure. This differentiation becomes more challenging in patients with Chronic Heart Failure as their symptoms tend to develop more insidiously over time, but there are always many subtle clues in the history and physical exam that can guide us to the correct diagnosis.
A case of cardiac asthma (cardiac cough):
A 66 year-old lady who is suffering from moist cough for about one year. She works as a librarian. She was mainly investigated for pulmonary causes of cough by a Chest X-Ray and CT scan. X-Ray had reported cardiac shadow as “borderline in size” with CTR of 0.52. CT scan was suggestive of “mild Bronchiectasis” with no features of emphysema or other significant lung pathologies. On this basis, a diagnosis of Bronchiectasis was made and she was given a few inhalers with no improvement in her condition.
During the consultation, she pointed out that her cough is mainly present at night and usually is worse in recumbent positions. She sometimes wakes up from sleep with a cough and mild dyspnea, which resolves after 5-10 minutes of walking. Initially, she did not elaborate much on exertional dyspnea, but on more questioning, she cited that she has actually reduced her workload, at work and home, in the past two years, and her ability to do what she was doing a few years ago has significantly diminished.
Here there are many clues pointing to a cardiac rather than respiratory etiology, including night-time cough and dyspnea, exertional dyspnea, fatigue and lethargy. This diagnosis could be substantiated by adding a few non-invasive and readily available investigations like ECG, and blood Pro-BNP levels. Her ECG is shown below,
ECG, Significant left bundle branch block (LBBB)
With a preliminary diagnosis of Chronic Heart Failure, she had an echocardiogram. Her left ventricle was moderate to severely dilated and there was severe global impairment of systolic function with an estimated ejection fraction of 20-25%. Right ventricular function and size were preserved and there was no “clinically significant” valvular pathology to explain her left ventricular dysfunction.
Conclusion and Discussion:
In the acute form, diagnosing Heart Failure (HF) is somehow straightforward. Patients present with clear signs and symptoms of HF, including dyspnea, fatigue, Paroxysmal Nocturnal Dyspnea (PND), Orthopnea, peripheral edema, raised JVP and abnormal heart and respiratory sounds. These are classic features of heart failure which can be very hard to miss.
On the other hand, Chronic HF diagnosis can be more challenging as the symptoms develop slowly over months or even years and patients adjust their lifestyle to cope with them. They may have vague and common complaints like fatigue, lethargy or cough that, in the first look, does not raise the suspicion of heart failure. At times, they may seek medical care when the disease is already far advanced. Here, keeping a “high index of suspicion” by the care provider is extremely important to avoid unnecessary and potentially deadly delays in making this life-threatening diagnosis.
Having an enlarged cardiac shadow on Chest X-Ray, even if borderline, in such patients should not be ignored. Our patient has a significantly abnormal ECG (Marked Left Bundle Branch Block) which needs to be investigated, even in the absence of symptoms. Lastly, with the widespread availability of non-invasive investigations like Echocardiogram and blood tests like BNP, chronic heart failure can be diagnosed much more efficiently only if our “index of suspicion” is high.
1. Kelder JC, et al. The diagnostic value of physical examination and additional testing in primary care patients with suspected heart failure. Circulation 2011; 124:2865.
2. Reddy YNV, et al. A Simple, Evidence-Based Approach to Help Guide Diagnosis of Heart Failure With Preserved Ejection Fraction. Circulation 2018; 138:861.
3. Lombardo T, Harrison T, Cardiac Asthma. Circulation. 1951;4:920–929