Cardiac Anesthesia in Valvular Heart Disease

Introduction

The heart has four valves; any damage can cause valvular heart disease. A patient having valvular heart disease can have heart failure. Valvular heart disease patients require surgery. The surgery and anesthesia require preoperative evaluation and care of the patient. This topic explains valvular heart diseases and the anesthesia used for these valvular heart disease patients during surgery.

What Is Valvular Heart Disease?

Valvular heart disease is any cardiovascular disease involving the heart's four valves. There are four valves in the heart. The aortic and mitral valves are on the left side of the heart. The pulmonary and tricuspid valves are on the heart's right side. These valves help the blood flow to the heart and prevent the backflow of blood in the associated chambers. These diseases can be congenital (by birth) or can develop on the increase in age factor. Valvular heart disease requires both medication and surgical approaches for management.

What Are Valvular Heart Disease Categories?

Valvular heart disease is classified according to the category of its cause. The classification is:

1. Congenital Valvular Heart Disease - These are the valvular diseases from birth. A few examples of them are atresia (complete abnormal blockage), stenosis (partial blockage), malposition (faulty position), and abnormalities of valves come under the congenital category.

2. Acquired Valvular Heart Disease - These diseases are not from birth but have been acquired in an individual with time. These diseases include endocarditis (infection of the heart lining), rheumatic heart disease (heart valve damage), and mitral valve prolapse. Rheumatic heart disease involves mitral stenosis, mitral regurgitation, aortic stenosis, and aortic regurgitation.

The most common valvular heart diseases are mitral stenosis and aortic stenosis.

When Is Cardiac Anesthesia Required in Valvular Heart Diseases?

Heart valvular disease patients require surgery. Cardiac anesthesia puts patients to sleep, providing them with a pain-free environment during surgery. Cardiac anesthesiologists must monitor anesthesia and heart activity and keep anesthesia safe during surgery.

How Is a Valvular Heart Disease Patient Managed Under Anesthesia?

Valvular heart disease patients require anesthesia during surgery. The anesthesia and other parameters of the body are managed during the surgery. Below are briefings on valvular diseases with anesthesia management.

Aortic Stenosis - Aortic stenosis occurs when the valve between the lower left heart chamber and the body's main artery aorta is narrowed and does not pass blood leading to reduced or blocked blood flow from the heart to the aorta and further to the whole body. It displays features like shortness of breath, heart murmurs (sound of the blood flowing through the heart), chest pain, and syncope (fainting). Systolic murmurs are also present. Chest X-rays and echocardiogram is done to diagnose.

• Anesthesia Management: Patients with aortic stenosis should focus on stable hemodynamics (blood circulation in the body) while going for anesthesia. Aortic stenosis causes low cardiac output. Efforts are to be made to maintain the normal rhythm of the heart. Apply defibrillator pads before anesthesia induction for rhythm maintenance. Tachycardia (fast heart rate) and bradycardia (slow heart rate) must be avoided. Alpha-adrenergic agonists are used to inhibit hypotension (low blood pressure). Good premedication can prevent tachycardia. The monitoring of the heartbeats with electrocardiography is required. Other parameters are also monitored by pulse oximetry and arterial blood pressure. An electrocardiogram is used to monitor hemodynamics. Sedation (anesthetics) is administered using low doses of Benzodiazepines, Fentanyl, Etomidate, and Sevoflurane. Tracheal intubation is also achieved by Vecuronium or Rocuronium bromide with a combination of sedative drugs.

Aortic Regurgitation - This condition occurs when the aortic valve is not closed completely, resulting in an inflow of blood into the ventricle chamber leaking backward. It shows features like left heart failure, difficulty breathing, or shortness of breath (dyspnoea). An electrocardiogram is used to diagnose its severity.

• Anesthesia Management: The anesthesia's primary goal is to keep a heart rate faster and avoid bradycardia. Tachycardia reduces the diastolic time (when the aortic valve should close) to decrease regurgitation. And the flow of blood is forward. Reduced systemic vascular resistance (resistance the system requires to form blood flow) will favor the forward flow. Inotropes (drugs that make the heart muscles beat) can also be needed, such as Milrinone and Dobutamine.

Mitral Stenosis - Mitral stenosis is the narrowing of the mitral valve. This valve does not open completely, resulting in the blocking of the blood into the left ventricle. It shows shortness of breath, swollen feet, heart murmurs, and irregular heart rhythms.

• Anesthesia Management: The goals of anesthesia are to control heart rate and reduce right and left ventricle contraction and ventricular preload. During the induction of anesthesia, blood pressure can increase. Therefore, monitoring heart pressure is necessary. Beta-blockers can also be used to control blood rates. Fluids are required to keep the heart pressure low. However, caution is taken in pulmonary hypertensive cases before giving fluids. All measures are taken to avoid pulmonary pressure. Oversedation should not be performed in these cases. Oxygen saturation and carbon dioxide levels should be monitored. Long surgeries can require inotropic support.

Mitral Regurgitation - Mitral Regurgitation occurs when the mitral heart valve between the left atrium and left ventricle does not close properly, allowing the blood to flow backward into the heart. It displays features like heart murmurs, irregular heartbeat, swollen feet, and shortness of breath.

• Anesthesia Management: The primary function of anesthesia is to maintain the forward flow of blood. High heart rates require short systolic time (when the blood flows into the aorta, contracting the ventricle requires the mitral valve to close). Conversely, a slow heart rate (bradycardia) can increase the systolic time and lead to left ventricle distension. Therefore, reduced vascular resistance is maintained with anesthesia use. Vasodilators and inotropic agents will also promote the forward flow of blood. Low doses of Ephedrine, Dobutamine, and Milrinone are used for continuous infusion.

What Are the Medications Used Along With Anesthesia in Valvular Disease Patients?

The medications are:

• Antibiotic prophylaxis.

• Anticoagulation.

• Beta-blockers.

• Statins.

• Recombinant BNP (brain type natriuretic peptide).

Conclusion

Diseases like valvular heart disease are rarely found in patients. However, the surgery performed on these patients requires serious attention. The primary goals of the anesthesia are essential to maintain while going for the surgery. Therefore, an anesthesiologist and a cardiologist are both needed in these cases. The premedications should be used as a precaution against infections or any increase in blood pressure during the surgery. After the procedure, the stability of the patient forms the recovery.