What is the management approach for abnormal heart sounds post cardiac surgery in the Cardiovascular Intensive Care Unit (CVICU)?

Management of Abnormal Heart Sounds Post Cardiac Surgery in CVICU

Immediate echocardiography is the first-line assessment for evaluating abnormal heart sounds in post-cardiac surgery patients, followed by appropriate hemodynamic management based on the specific cardiac dysfunction identified. 1

Types of Abnormal Heart Sounds and Their Clinical Significance

• New systolic murmurs may indicate mitral regurgitation resulting from myxomatous degeneration or post-infarction left ventricular remodeling 1
• Diastolic murmurs suggest aortic regurgitation requiring attention to volume control and afterload reduction 1
• Muffled prosthetic valve sounds or new murmurs around prosthetic valves may indicate prosthetic valve dysfunction requiring immediate evaluation 1
• Heart sounds are objectively altered after coronary artery bypass graft (CABG) surgery, with sounds generally shifting toward lower frequencies 2

Initial Evaluation Approach

• Perform thorough auscultation to detect new murmurs or muffling of prosthetic heart sounds 1
• Obtain an ECG to identify arrhythmias, ischemic changes, or conduction abnormalities 1
• Use transesophageal echocardiography (TEE) for immediate bedside visualization of cardiac function, valvular status, and to differentiate between right, left, and global heart failure 3
• Consider pulmonary artery catheterization (PAC) for direct measurement of circulatory blood flow, especially in right ventricular failure 3
• Assess for dynamic indicators of fluid responsiveness rather than static parameters like central venous pressure or pulmonary capillary wedge pressure 3

Management Based on Specific Cardiac Dysfunction

Left Ventricular Dysfunction

• For myocardial dysfunction, consider low-to-moderate doses of dobutamine and epinephrine to improve stroke volume while moderately decreasing pulmonary capillary wedge pressure 3
• Milrinone decreases pulmonary capillary wedge pressure and systemic vascular resistance while increasing stroke volume with less tachycardia than dobutamine 3
• Levosimendan increases stroke volume and heart rate while decreasing systemic vascular resistance 3
• For heart failure with suspected coronary hypoperfusion, an intra-aortic balloon pump is highly recommended 3

Right Ventricular Dysfunction

• Introduce a pulmonary artery catheter after echocardiographic diagnosis of RV failure to differentiate between pulmonary hypertension and RV ischemia 3
• Reduce RV afterload as the ischemic right ventricle is very sensitive to afterload increases 3
• Monitor closely as RV dysfunction is present in about 40% of postoperative patients who develop shock 3

Valvular Abnormalities

• For mitral regurgitation, consider afterload reduction and diuretics to achieve hemodynamic stabilization 1
• For aortic regurgitation, focus on volume control and afterload reduction; avoid unusually slow heart rates 1
• For prosthetic valve thrombosis in hemodynamically stable patients with recent subtherapeutic anticoagulation, use intravenous heparin initially 1

Vasoplegic Syndrome

• Use norepinephrine in cases of low blood pressure due to vasoplegia to maintain adequate perfusion pressure 3
• Repeatedly assess volume status to ensure the patient is not hypovolemic while under vasopressors 3
• Consider vasopressin (0.06 U/min) as an alternative if catecholamines and fluid infusions fail to improve hemodynamics 4
• For refractory vasoplegia, methylene blue may be used as rescue therapy 4

Management of Arrhythmias

• Beta-blockers are recommended as first-line therapy for rate control in supraventricular arrhythmias, including atrial fibrillation 1
• For hemodynamically unstable patients with arrhythmias, electrical cardioversion is indicated 1
• Correct underlying causes of arrhythmias, including electrolyte abnormalities and optimizing oxygenation 1
• For new postoperative sinus node dysfunction or atrioventricular block with persistent symptoms or hemodynamic instability, consider permanent pacing before discharge 1

Monitoring and Follow-up

• Implement systematic monitoring of stroke volume as part of goal-directed therapy 5
• Use dynamic measurements of hemodynamic parameters to assess volume status rather than static measurements 5
• Schedule the first post-operative visit within 6 weeks of discharge 1
• Establish baselines for continued follow-up, including assessment of symptomatic status and physical signs 1

Common Pitfalls to Avoid

• Do not ignore even mild reduction of left ventricular ejection fraction in patients with mitral regurgitation, as it may indicate reduced ventricular reserve 1
• Avoid unusually slow heart rates in patients with severe aortic regurgitation, as this can increase the volume of regurgitation 1
• Do not overlook the need for endocarditis prophylaxis in patients with prosthetic valves 1
• Avoid assuming cardiovascular dysfunction is solely related to cardiac function when vascular dysfunction may be the primary issue 5
• Be aware that noise levels in ICUs (measured between 59-60.8 dB(A)) can adversely affect heart rate and blood pressure of patients, potentially complicating management 6