From the Guidelines
Systole and diastole are the two phases of the cardiac cycle, with systole being the contraction phase where the heart pumps blood out to the body, and diastole being the relaxation phase where the heart chambers fill with blood. The cardiac cycle is a complex process that involves the coordinated contraction and relaxation of the heart muscle to pump blood throughout the body.
- Systole is the phase of the cardiac cycle where the heart contracts to pump blood out to the body, beginning with electrical signals that cause the ventricles to contract forcefully, ejecting blood into the pulmonary artery and aorta 1.
- Diastole, on the other hand, is the relaxation phase where the heart chambers fill with blood, during which the ventricles relax and expand as they fill with blood from the atria, preparing for the next contraction 1. Key aspects of these phases include:
- Systolic pressure, the higher number in a blood pressure reading, represents the force exerted on artery walls during systole.
- Diastolic pressure, the lower number in a blood pressure reading, indicates the arterial pressure when the heart is at rest between beats. Understanding these phases is crucial for healthcare providers to assess cardiac function and diagnose conditions like hypertension, where abnormal pressures during these phases may indicate cardiovascular problems 1. The most recent and highest quality study, 1, provides valuable insights into the assessment of functional capacity in clinical and research settings, highlighting the importance of measuring cardiopulmonary indexes during exercise to evaluate therapy, estimate risk, and stratify patients appropriately for transplantation. In the context of heart failure, both systolic and diastolic dysfunction can lead to reduced exercise tolerance, and symptoms may first manifest as dyspnea or fatigue during physical activity 1. Therefore, accurate understanding and measurement of systole and diastole are essential for the diagnosis and management of cardiovascular conditions, and healthcare providers should prioritize these aspects in their clinical practice.
From the Research
Definition of Systole and Diastole
- Systole refers to the phase of the cardiac cycle when the heart muscle contracts and pumps blood from the chambers into the arteries 2.
- Diastole refers to the phase of the cardiac cycle when the heart muscle relaxes and the chambers fill with blood 2.
Role in Heart Failure
- Systolic heart failure occurs when the heart is unable to contract effectively, leading to a decrease in cardiac output 2.
- Diastolic heart failure occurs when the heart is unable to relax and fill with blood properly, also leading to a decrease in cardiac output 2.
Treatment Options
- Beta-blockers are commonly used to treat systolic heart failure, as they can help reduce the heart's workload and improve its pumping efficiency 2, 3, 4.
- ACE inhibitors are also used to treat heart failure, as they can help relax blood vessels and reduce blood pressure 3, 5, 4.
- The combination of beta-blockers and ACE inhibitors can be effective in treating heart failure, as they work together to improve cardiac function and reduce blood pressure 3, 4.
Blood Pressure Control
- Beta-blockers, ACE inhibitors, calcium channel blockers, and diuretics can all be used to control systolic hypertension, but their effectiveness may vary depending on the individual patient 6.
- Diuretics and calcium channel blockers may be more effective in elderly patients with systolic hypertension, while beta-blockers may be less effective and have more side effects 6.