The Patient History
Obtaining a good medical history is always the starting point for a thorough clinical evaluation, cardiovascular or otherwise. The components of a complete history include:
- Confirming signalment
- Using open-ended questions to establish and explore the chief presenting complaint(s)/concern(s)
- Refining the chief concern(s) using open- and closed-ended questions to develop detailed understanding of the nature of the problem(s)
- Includes onset, duration, frequency, severity, location, timeline of progression or improvement, and any treatments administered and response to those treatments
- Obtaining body systems review to identify localizing or non-localizing signs that may be related to the chief concern(s) or may represent additional concerns
- Includes attitude, activity level, behaviour, appetite, drinking, urinating, defecating, and presence of other abnormalities like vomiting, diarrhea, coughing, sneezing, collapse, seizures, lameness, masses, etc.
- Establishing other risk factors by inquiring about diet, environment, travel history, vaccination and parasite prevention history, and concurrent or previous illnesses or treatments
In the cardiovascular patient in particular, history details can be critical in assessing risks for certain heart diseases (factors like family history, diet, environment, travel history) and establishing probability of current congestive heart failure. History details are also critical for investigating specific presenting concerns like coughing, difficulty breathing, and collapse episodes, and should trigger a specific series of targeted questions. The sections below provide specific guidance on history taking in the cardiovascular patient.
Historical findings in patients with cardiovascular disease
Some patients with cardiovascular disease may present without any clinical signs (asymptomatic) and their disease is detected incidentally on physical examination and other evaluations. These patients have preclinical disease. Preclinical disease does not always mean mild disease – some patients may have substantive heart disease in the absence of any clinical signs noted by the owner.
Alternatively, patients with clinical signs due to cardiovascular disease may experience one or several of the following:
- Lethargy/weakness/reduced exercise tolerance – due to reduced skeletal muscle perfusion
- Syncope – due to reduced cerebral perfusion
- Tachypnea/dyspnea/orthopnea – Tachypnea and dyspnea associated with heart disease are most often due to pulmonary edema (left heart failure) or pleural effusion (right heart failure, or left heart failure in cats). Tachypnea is a sensitive sign for the onset of congestive heart failure in patients with heart disease, and owners can become very practiced at monitoring home resting respiratory rates. Not all dogs with pulmonary edema will simultaneously experience cough. Orthopnea is difficulty breathing when lying down. This may occur because of the shift in circulating volume centrally (to heart and lungs) that happens in the recumbent or sedentary state.
- Cough – cough, when present on its own (i.e. in absence of other respiratory signs), is rarely caused by heart disease and more likely to be associated with airway disease. Bronchial compression from an enlarged left atrium may be a cardiac contributing factor to cough in dogs with concurrent airway disease. Dogs with severe pulmonary edema may cough as a clearance mechanism, though these dogs will have concurrent tachypnea +/- dyspnea. That is, cough on its own is NOT an indicator of pulmonary edema. Cough in cats is rarely ever associated with cardiac causes, and typically indicates respiratory disease.
- Abdominal distention – due to ascites and/or hepatomegaly or splenomegaly from venous congestion (right heart failure)
- Decreased appetite/weight loss – any patient that doesn’t feel well may have a reduced appetite. Weight loss may follow from reduced intake and is also a result of the catabolic state of cardiac cachexia in chronic heart failure.
- Gastrointestinal signs (diarrhea/vomiting) – while not typically the primary presenting concerns in patients with heart disease, gastrointestinal (GI) signs may occur in patients with right heart failure due to intestinal wall congestion and edema, or in patients with concurrent renal or pre-renal azotemia. GI signs like nausea and vomiting may be primary presenting concerns in patients with tachyarrhythmias or pericardial effusion.
Targeted questioning for specific clinical signs
The following section outlines specific information that is desirable in history taking for specific clinical signs, in the interest of understanding the problem and narrowing differential diagnoses.
Disorders of many different body systems may produce exercise intolerance, including the cardiovascular, respiratory, musculoskeletal, neurologic, endocrine, and hematologic systems. The following information may help refine body system(s) involved, and are meant to be complementary to the components a full history outlined above.
- Are there any changes in the patient’s behaviour or gait in between exercise events?
- Is the exercise intolerance predictable? Does it occur with all types, intensities, and durations of exercise? Or are there specific activities likely to trigger?
- When was it first noticed and is it getting worse?
- Associations with time of day or temperature?
- Is the patient noted to be stiff, lame or painful? Is there incoordination (ataxia)? And for any of these, which limbs are affected?
- Does difficulty breathing or noisy breathing accompany the exercise intolerance?
- Is there any change in mentation associated with the exercise intolerance?
Syncope is a cardiovascular collapse episode characterized by sudden and transient loss of consciousness and postural tone due to decreased cerebral perfusion. Pre-syncope refers to near loss of postural tone (stumbling, weakness, ataxia) without or with partial loss of consciousness. These events must be differentiated from other transient events that lead to collapse like seizure, musculoskeletal or neurologic conditions, airway obstruction, hypoglycemia, narcolepsy, etc. Detailed history, and in particular descriptions of the events, are critical in the investigation of these transient episodes. Collapse events are often very stressful for owners to witness, and their recall on details may not always be accurate or may come with a number of assumptions, creating more of a challenge. Careful, calm, and detailed questioning is required. Video recordings of events, while difficult to acquire, can be extremely helpful in better understanding the nature of collapse episodes.
- What was the patient doing at the time of the episodes (resting vs active, sleep vs awake) and are there any identifiable triggering events (exercise, excitement, coughing, urinating, defecting, other)?
- What behaviours are witnessed immediately before and during the episode, including vocalization, being flaccid vs rigid, involvement of front vs hind vs all four limbs, paddling or tonic clonic movements, urination, defecation, drooling, facial involvement (twitching, blinking, jaw chomping)? Note that while it is important to collect all of these details, there is a great deal of overlap between syncope and seizure in the behaviours that may be witnessed. See summary below.
- How long do the episodes last? How long does it take for the patient to return to normal? Syncope is often very transient (seconds to 1-2 minutes) whereas seizure events may be more protracted with a post-ictal phase of abnormal behaviour.
- Duration and frequency of episodes
- Is the patient normal in terms of behaviour, mentation, gait, activity in between episodes. Patients with syncope typically are normal in between episodes.
How syncope and seizure can look similar
- Both result in collapse and loss of consciousness
- Both can involve similar behaviours during like vocalization, tonic-clonic movement (often repetitive paddling in seizure vs flailing to get up in syncope), involuntary urination or defecation
How syncope and seizure may be different
- Episodes occurring while at rest or during sleep are more typical of seizure, whereas syncope is often associated with activity, exercise, or excitement
- Specific triggering events immediately before the collapse like excitement, fear, urination, defecation, coughing, choking, may suggest vasovagal syncope
- Abnormal behaviour or facial involvement before the episode (pre-ictal phase) suggests seizure
- A protracted period of abnormal behaviour or altered mentation after the episode (post-ictal phase) suggests seizure
- Syncope is very transient with return to normal within 30 seconds to 1-2 minutes
- Facial involvement such as twitching, blinking, or jaw chomping suggests seizure
- The flaccid patient is more suggestive of syncope, but prolonged syncope can also result in opisthotonus and rigidity
Sometimes the first step is to establish that what the client is witnessing is indeed cough and not some other event (like vomiting, sneezing, gagging, reverse sneezing, etc). Video recordings of the patient can be very helpful in this regard. While the character of cough is rarely helpful in determining etiology, the following information is desirable in understanding the problem.
- Is the cough accompanied by tachypnea and/or dyspnea? This is important in establishing urgency/severity of the problem, and also in determining whether pulmonary edema (congestive heart failure) should be on the differential diagnosis list.
- Is the cough accompanied by other localizing signs like nasal discharge or sneezing? (suggesting upper respiratory causes)
- Duration and frequency help to establish whether acute or chronic as well as severity
- Are there particular triggers for the cough?
- Whether the cough is productive (“wet”, associated with expectoration or swallowing) or not (“dry”, no expectoration) is rarely helpful as there is tremendous overlap in witnessed signs and underlying causes. Exceptions may include the “honking” cough classically associated with tracheal collapse, and whether there is any production of blood or blood-tinged fluid, both of which raise concern for more serious respiratory or cardiac disorders.
- Understanding the patient’s home and outdoor environment are very important, as exposure to irritants such as dust, molds, fireplace or cigarette smoke, home renovations, aerosols or other fumes, may cause or contribute to cough. Recent kennel or boarding history or exposure to other dogs raises concern for infectious causes, and geography is important in understanding prevalence of particular parasites and other infectious diseases.
- Have any treatments been administered and what was the response? Note that a ‘response’ to furosemide (diminished cough with furosemide) is NOT diagnostic for pulmonary edema/congestive heart failure. Placebo effect, bronchodilating effect, and drying of other secretions can lead to this type of improvement. Improvement in tachypnea and radiographic lung appearance, with or without improvement in cough, are typical of positive response to furosemide in the setting of congestive heart failure.