Diastole and Ventricular Filling

Diastole and Cardiac Function

• Diastole refers to the relaxation phase where all four heart chambers relax simultaneously, allowing ventricles to fill with blood.
• Atrioventricular (AV) valves separate the atria from the ventricles, ensuring unidirectional blood flow.

Heart Circulation

• The right side of the heart (right atrium, right ventricle) handles deoxygenated blood, distributing it to the lungs via the pulmonary artery for oxygenation.
• The left side of the heart (left atrium, left ventricle) distributes oxygenated blood to the body via the aorta, receiving oxygen-rich blood from the lungs through four pulmonary veins.

Heart Valves

• AV valves prevent regurgitation into the atria during ventricular contraction.
• The tricuspid valve separates the right atrium from the right ventricle, while the pulmonary and aortic valves open based on pressure changes in the ventricles.

Cardiac Cycle

• Ventricular systole begins with an increase in ventricular pressure, causing closure of AV valves and opening of semilunar valves, allowing blood ejection into the pulmonary artery and aorta.
• At the end of systole, pressure decreases, leading to closure of semilunar valves and the onset of diastole, restarting the cardiac cycle.

Nervous System and Heart Rate

• Heart rate is regulated by the sympathetic and parasympathetic nervous systems, impacting the SA node.
• Vagus nerve stimulation decreases heart rate, whereas sympathetic stimulation increases it through beta-1 receptor activation.

Medical Devices for Heart Management

• Pacemakers consist of a generator and leads placed under the skin, controlling heartbeat by delivering impulses.
• Implantable cardioverter-defibrillators (ICDs) monitor heart rhythm and deliver shocks to restore normal rhythm in case of abnormal rhythms.

Surgical Interventions

• Coronary artery bypass grafting (CABG) involves bypassing blocked arteries to improve heart blood flow.
• Percutaneous coronary intervention (PCI), previously known as angioplasty with stent, is used to widen narrowed arteries.

Hemodynamic Monitoring

• Measurements of central venous pressure (CVP), blood pressure (BP), and pulmonary artery pressures are crucial in critical care.
• Complications from catheters include pneumothorax, infection, and hemorrhage; therefore, monitoring during insertion is essential.

Pulmonary Artery Pressure Monitoring

• Used for assessing left ventricular function and response to medical interventions, using various catheters based on clinical needs.
• Fluoroscopy may assist in visualizing catheter placement during insertion.

Left Atrial Pressure Monitoring

• Provides valuable hemodynamic information related to left-sided cardiac structures and function.
• Access to left atrial pressures can be obtained through transthoracic or transseptal routes, important for evaluating conditions like left atrial hypertension.

This quiz explores the diastolic phase of the cardiac cycle, where all four heart chambers relax simultaneously. Participants will learn about the significance of diastole in allowing the ventricles to fill with blood in preparation for the next contraction. Test your understanding of this critical phase in heart function.