What is cardiac asthma or cardiac cough?
For centuries, we’ve understood that heart diseases can lead to symptoms like shortness of breath, cough, and even wheezing similar to what asthmatic patients experience. The term “Cardiac Asthma” has been casually used for many years to describe this group of symptoms. However, it specifically refers to a chronic cough and wheezing during exhalation that resembles the symptoms of bronchial asthma.
In 1833, the term “Cardiac Asthma” was first introduced by James Hope, an English physician, in medical literature. Two decades later, renowned Irish physician William Stokes firmly established the term as a medical diagnosis. James Hope, often regarded as the first “Modern Cardiologist” in history, made numerous discoveries in the field of cardiology. He theorized that diseases affecting the left ventricle could increase the blood volume in the heart, creating an obstruction to blood flow from the left atrium to the left ventricle. This blockage then propagates backward toward the pulmonary vasculature, resulting in pulmonary congestion, edema, cough, wheeze, and shortness of breath. In 1897, William Osler further defined this condition as follows:
In cases of advanced arteriosclerosis, there are often attacks of dyspnea of great intensity recurring in paroxysms, often nocturnal. The patient goes to bed feeling quite well and, in the early morning hours, wakes in an attack which, in its abruptness of onset and general features, resembles asthma. Two other features about this form of attack will attract your attention, the evident effort in the breathing and the presence of wheezing in the bronchial tubes and of moist rales at the bases of the lungs.
Though the term “Cardiac Asthma” is not as commonly used today, revisiting historical papers offers valuable insights into the remarkable understanding of disease pathophysiology that these medical pioneers possessed, despite the lack of advanced investigative technology we have today. One such paper is a sophisticated article published in 1951 by Tinsley Harrison, the author of Harrison’s Textbook of Internal Medicine. In this article, he extensively discusses the definition of cardiac asthma and the pathophysiology of shortness of breath in various heart diseases. The concluding paragraph of the article is as follows:
A severe attack of cardiac asthma associated with rapidly developing pulmonary edema constitutes one of the commonest and gravest of all medical emergencies. There are few conditions in the broad domain of internal medicine in which prompt and energetic therapy, based on an understanding of the mechanism of the disorder, can produce such immediate and gratifying benefits.
Gradual Progression of Heart Failure Symptoms and the Emergence of Cardiac Asthma
In Chronic Heart Failure (HF), patients might unintentionally decrease their physical activity, which makes it more challenging to identify or report symptoms. Therefore, taking a comprehensive medical history is crucial for accurate diagnosis. It is essential to ask patients specific questions about any changes in their activity levels compared to an earlier time, such as whether they can climb a flight of stairs with the same ease as a year or a month ago.
Initially, dyspnea may only manifest during physical activity, not at rest, with patients primarily reporting fatigue, lethargy, and anorexia. Peripheral bilateral edema might initially occur intermittently but become more resistant to simple treatments and less likely to resolve spontaneously as the disease advances, ultimately necessitating therapy.
Pathophysiology:
During heart failure, the heart’s diminished pumping capacity causes blood to accumulate in the lung vessels, increasing pressure in the pulmonary circulatory system. This heightened pressure forces fluid to leak from blood vessels into lung tissues and air spaces (alveoli), leading to pulmonary congestion and edema (fluid buildup in the lungs). The fluid irritates the airways, inducing coughing and wheezing, which resemble symptoms experienced by asthma patients. These symptoms are more prominent at night while lying down. Initially, symptoms alleviate when the patient sits or stands upright, but they become more severe as heart failure progresses. Symptoms can include pulmonary congestion (edema), intensified coughing, profuse cold sweats, and rales (widespread bubbling sounds during respiratory auscultation). In 1915, English physician Sir Thomas Allbutt described a patient with pulmonary edema as follows:
As I enter upon this paragraph, I see again with the vividness of light, the desperate conflict of a strong man with a paroxysm of suffocation, which recently some of us witnessed in a hospital ward during an examination. The patient, seized and throttled before he could cry out, sprang up livid to wrestle with death. The desperate conflict made the fell enemy almost visible to us. Now this way, now that, springing up in bed to fight from the urge of it, to sink back in utter exhaustion, but only to rise again panting, with the sweat streaming from him, desperately to renew the battle, the scene was almost as distressing to the bystanders as to the victim.
The Challenge:
Despite the wealth of knowledge accumulated over the years, “cardiac asthma” cases are occasionally misdiagnosed as “bronchial asthma” or other respiratory illnesses such as Bronchiectasis. It is crucial to distinguish between respiratory causes of coughing and wheezing and secondary causes, primarily heart failure. This differentiation can be more challenging in patients with Chronic Heart Failure, as their symptoms often develop gradually and subtly. However, numerous subtle indicators in a patient’s medical history and physical examination can help guide healthcare professionals toward the correct diagnosis.
A case of cardiac asthma (cardiac cough)
A 66-year-old woman has been experiencing a persistent, moist cough for about a year. She works as a librarian and has undergone tests to determine the pulmonary cause of her cough, including a chest X-ray and a CT scan. The X-ray revealed a cardiac shadow described as “borderline in size” with a CTR of 0.52. The CT scan suggested “mild bronchiectasis” but showed no signs of emphysema or other significant lung abnormalities. Based on these findings, she was diagnosed with bronchiectasis and prescribed inhalers, which did not improve her condition.
During the consultation, she mentioned that her cough primarily occurs at night and worsens when lying down. Occasionally, she wakes up due to coughing and mild shortness of breath, which resolves after 5-10 minutes of walking. At first, she did not discuss exertional dyspnea in detail, but upon further questioning, she admitted that she had reduced her workload at work and home over the past two years. Her ability to perform tasks she was capable of a few years ago has significantly declined.
In this case, several clues suggest a cardiac origin rather than a respiratory one, including nighttime coughing and shortness of breath, exertional dyspnea, and fatigue. This diagnosis could be confirmed by performing a few non-invasive and readily available tests, such as an ECG, echocardiogram and measuring blood Pro-BNP levels. Her ECG is shown below:
ECG showing marked Left Bundle Branch Block (LBBB)
Echocardiogram findings
Based on an initial diagnosis of Chronic Heart Failure, she underwent an echocardiogram. Her left ventricle was found to be moderate to severely dilated, with significant global impairment of systolic function and an estimated ejection fraction of 20-25%. The size and function of her right ventricle were preserved, and no “clinically significant” valvular abnormalities were detected to account for her left ventricular dysfunction.
Conclusion and Discussion
Diagnosing acute Heart Failure (HF) can be straightforward, as patients often exhibit clear signs and symptoms, such as dyspnea, fatigue, Paroxysmal Nocturnal Dyspnea (PND), orthopnea, peripheral edema, elevated JVP, abnormal heart and respiratory sounds. These classic features of heart failure can be difficult to overlook.
Conversely, diagnosing Chronic HF can be more challenging since symptoms may develop gradually over months or even years, causing patients to adapt their lifestyles to accommodate these changes. They might experience non-specific and common complaints like fatigue, lethargy, or cough, which, at first glance, do not necessarily indicate heart failure. Sometimes, patients only seek medical attention when the disease is already quite advanced.
Chronic cough can have many causes, but one that should not be overlooked is a cough that disrupts a patient’s sleep and worsens when lying down, particularly if accompanied by fatigue and diminished exercise capacity. If the cough does not respond to treatments such as respiratory inhalers or Proton Pump Inhibitors (PPIs), it can indicate that an alternative underlying cardiac issue may be the cause. Therefore, healthcare providers must maintain a “high index of suspicion” to prevent unnecessary and potentially fatal delays in diagnosing this life-threatening condition.
In patients experiencing such symptoms, an enlarged cardiac shadow on a Chest X-Ray should not be disregarded, even if only borderline. Our patient presents a notably abnormal ECG (marked Left Bundle Branch Block), which warrants further investigation, even without symptoms. Finally, thanks to the widespread availability of non-invasive tests like Echocardiograms and blood tests like BNP, chronic heart failure can be diagnosed more efficiently, as long as healthcare providers maintain a high “index of suspicion.”
References
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
