Medical Psychology – Lecture 7 (UNIVERSITY OF AMSTERDAM)

The clinical manifestations of cardiovascular disease are a combination of the gradual increase in underlying risk factors and acute triggers. Anger is a risk factor for cardiovascular disease. The stages of progression of cardiovascular disease are gradual subclinical disease progression (1), vulnerable disease stage (2) and presentation of acute coronary syndromes (3).

There is systemic circulation (i.e. blood through the body due to the heart) and the pulmonary circulation (i.e. blood to the lungs). The heart is a pump. It pumps oxygenated blood out of the left ventricle and pumps used blood through the lumps via the right ventricle. It receives its own blood supply from coronary arteries.

There are several types of cardiovascular disease:

1. Coronary heart disease (CHD)
2. Coronary artery disease (CAD)
3. Myocardial infarction (MI)
4. Heart failure (HF)
5. Valve disease
6. Arrhythmias (i.e. sudden cardiac death)
7. Stroke

Myocardial ischemia develops when cardiac demand exceeds coronary blood supply to the heart muscle. Increases in central and autonomic nervous system activity are a common phenomenon that links acute psychologic, psychiatric and neurologic events to major cardiac pathologies. Myocardial infarction is associated with a higher prevalence of work, home and financial stress (1), major life events (2), lower locus of control (3) and more depression (4).
 

The gradual disease progression of cardiovascular disease is influenced by modifiable factors (e.g. hypertension, diabetes, smoking, psychosocial factors, weight) and unmodifiable factors (e.g. age, sex, genetics). The treatment of coronary heart disease involves coronary angioplasty (i.e. dotting) (1), a bypass (2) or thrombolysis (3). 

There are three types of psychological risk factors for cardiovascular disease:

1. Acute factors (i.e. triggers)
   These factors are risk factors that act as triggers of cardiac events.
2. Episodic factors (e.g. depression)
   These factors are risk factors that last from 2 weeks to 2 years.
3. Chronic factors (i.e. traits)
   These factors are near-permanent risk factors that promote the gradual progression of coronary artery disease.

The acute factors are involved in the end-stage of the development of cardiovascular disease. The episodic and chronic factors are involved in the development of cardiovascular disease. Chronic risk factors are associated with increased reactivity to acute stressors and promote the risk of development of episodic risk factors.

Plaque activation rather than gradual disease progression may be primarily involved in the adverse risk associated with episodic risk factors. Episodic risk factors may not last long enough to initiate and sustain an atherosclerotic process.

The associations between psychological factors and disease progression depend on the nature of the underlying disease (i.e. severity). Most psychological risk factors for cardiovascular disease are sub-threshold (i.e. not meeting diagnostic criteria for psychological disorders). Elevated levels of general distress, subclinical depression and depression are risk factors for cardiovascular diseases.

Eustress refers to the stress evoked by positive emotions or events. Distress refers to stress evoked by negative feelings and events. Distress response refers to how environmental factors threaten us, how these factors are interpreted and how these factors make us feel. Time (1), control (2) and individual vulnerability (3) influence the stress response. The Yerkes-Dodson Law states that there is an optimal level of stress exposure. 

Acute psychological factors (i.e. emotions) are related to environmental factors (e.g. earthquake). Mental stress ischemia refers to a decreased cardiac supply and increased cardiac demand. 

The ECG is a measure of the changes in electrical loading of extracellular fluid due to electrical changes that occur in all cardiac muscle cells together. It represents all phases of the conduction pathway. There is a greater risk of ischemia when experiencing negative emotions. It is possible that positive emotions are a protective factor of ischemia. 

There is a decrease in heart rate variability prior to ischemia. The level of parasympathetic activity is lower in patients who have a mental stress-induced ischemic event. High levels of mental arousal are associated with low levels of parasympathetic activity. 

Panic (i.e. panic disorder) is a risk factor for ischemia. Mental stress leads to an extra narrowing of coronary arteries. Mental stress-induced ischemia is observed in 30%-70% of patients with coronary artery disease. Reduced coronary supply plays an important role. Mental stress-induced ischemia is associated with poor prognosis and increased risk of mortality.

Mental stress-induced ischemia (30-70% of patients with coronary artery disease)

• Is rarely detectable with ECG
• Requires myocardial functional or perfusion imaging
• Is often asymptomatic
• Is more common in patients with exercise-inducible ischemia than in patients without exercise-inducible ischemia.
• Is associated with ambulatory ischemia
• Occurs at a lower heart rate (i.e. lower cardiac demand than with exercise)

Reduced coronary supply plays an important role in mental stress-induced ischemia. It is associated with a poor prognosis and an increased risk of mortality. Mental stress can trigger myocardial infarction and myocardial ischemia during daily life. This is partially mediated by changes in autonomic nervous system activity.

Takotsubo cardiomyopathy (TTC) is typically triggered by an emotional event. The contraction pattern of the left ventricle does not contract symmetrically any more. This is normally only seen with severe myocardial infarction. This syndrome appears to be the same as myocardial infarction but there is minimal coronary artery disease. It is more common in women.

Severe psychological distress is associated with an increased risk of myocardial infarction. Depression is a risk factor for cardiovascular disease but cardiovascular disease is also a risk factor for depression. Depression is not a direct by-product of underlying coronary artery disease or poor heart function.

Depression is associated with biological risk factors and adverse health behaviours (e.g. physical inactivity) in patients with both depression and cardiovascular disease. In these patients, somatic depressive symptoms and irritability are more common than typical depressive symptoms.

There are four pathways that play a primary role in episodic and chronic risk factors:

1. Central nervous system
2. Autonomic nervous system (i.e. parasympathetic and sympathetic)
3. Blood clot formation
4. Inflammation and immune dysregulation

There are elevated markers of chronic inflammation in depressive disorders (e.g. IL-6). Low-grade inflammation may alter the stability of atherosclerotic plaques and increase the risk of plaque rupture leading to acute coronary syndromes.

Psychological factors influence medical conditions through their effect on biological processes (e.g. central nervous system, autonomic nervous system, endocrine, homeostasis). This, in turn, influences the disease outcome. Psychological factors also influence behaviour (e.g. health behaviours, symptom reporting, seeking medical care). This, in turn, influences the disease outcome.

Acute mental stress induces myocardial ischemia in patients with cardiovascular disease, which is a precipitant of cardiac events. The pathways linking depression to adverse cardiovascular disease outcomes may require inflammation and autonomic nervous system dysregulation as co-factors.

There is an association between hostility and the severity of underlying coronary disease and an association with incident myocardial infarction. This association is stronger in young men. Type D personality reflects a general propensity to psychological distress that adversely affects cardiovascular outcomes.

Post-traumatic stress disorder is a chronic risk factor and is predictive of increased health care use (1), adverse cardiovascular risk factors (2) and increased cardiovascular morbidity and mortality (3). The association between PTSD and adverse cardiac outcomes may be explained by underlying psychological vulnerability.