The Role of Hemostasis in Cardiovascular Surgery

The Role of Hemostasis in Cardiovascular Surgery

Bleeding is a common complication in cardiovascular surgery, worsens the patient’s prognosis, and is often caused by perioperatively acquired hemostatic abnormalities.¹ Significant blood loss leads to transfusion, but transfusion is also independently associated with negative outcomes.² Thus, bleeding is detrimental and costly, and prevention of bleeding can be expected to have tremendous effects on reallocation of resources.² 

This blog will explore the topic of hemostasis in cardiovascular surgery, delving into the complexities of bleeding control during these critical procedures. Here, Torben Colberg, MD, MBA, Vice President of Advanced Surgery Worldwide Medical at Baxter Healthcare, provides an overview of the intricacies of hemostasis, highlighting the significance of key technologies and approaches in enhancing surgical safety and effectiveness.

Introduction

Effective hemostasis as part of a blood management strategy is a critical requirement for patients undergoing surgery.³ A variety of principles help to guide surgeons and operating room (O.R.) staff in achieving hemostasis during cardiovascular procedures. Depending on the procedure and circumstances, a range of approaches may be used. Keep reading to learn more about the role of hemostasis in cardiovascular surgery. We will begin with foundational information, then focus on specifics techniques and interventions, including topical hemostatic agents. 

Cardiovascular Surgery: A Primer 

Cardiovascular surgery encompasses a broad range of procedures aimed at treating diseases and conditions affecting the heart and blood vessels.⁴ This includes coronary artery bypass grafting (CABG) for coronary artery disease, heart valve repair or replacement, aneurysm repair, heart transplantation, insertion of a ventricular assist device, and surgeries for congenital heart disease, among others.^5,6  These procedures are critical for addressing cardiovascular disease, the leading cause of morbidity and mortality worldwide, and rising health care costs.^4,7

The Essence of Hemostasis in Surgery 

Hemostasis, in the broadest sense, refers to the process of cessation of bleeding.⁸ A more refined clinical definition of hemostasis is bleeding control without the induction of pathologic thrombotic events such as myocardial infarction, stroke, arterial thrombosis, or deep vein thrombosis (Figure 1).⁸ The process involves a complex cascade of events leading to the formation of a stable blood clot, including vascular constriction, activation of coagulation factors, and platelet plug formation.⁹ 

In the surgical context, achieving hemostasis is paramount to prevent excessive blood loss, which can compromise patient recovery and outcomes.^10,11  In the United States, national data has shown that cardiac surgical procedures utilize somewhere between 10 and 15% of the approximately 15 million units of packed red blood cells received by surgical patients annually.¹²

Acquired Hemostatic Abnormalities in Cardiovascular Surgery 

In the realm of cardiovascular surgery, factors contributing to acquired hemostatic abnormalities include the use of anticoagulants as well as the activation and consumption of coagulation factors and platelets induced by cardiopulmonary bypass (CPB).¹

To counteract the stimulation of intrinsic and extrinsic coagulation pathways as a result of CPB, patients are systematically heparinized.¹² The pathophysiology of bleeding after CPB is multifactorial and complex, involving hypothermia, hemodilution, activation of coagulation, endothelial cell and tissue injury, foreign-surface contact, consumption of clotting factors, platelets activation, platelets dysfunction and hyperfibrinolysis.¹³ 

Critical Nature of Limiting Bleeding 

Bleeding can be a complication of surgery that may lead to substantial morbidity and mortality.¹⁴ In cardiac surgery, severe bleeding occurs in approximately 7% of cases and is associated with an increased risk of postoperative mortality.¹⁴  Limiting bleeding during cardiac surgery is vital to maintaining the patient's hemodynamic stability and minimizing the risk of transfusion-related complications.¹³

In addition, patients undergoing cardiac surgery are prone to perioperative hemostatic abnormalities requiring surgical revision in 2% to 6% of patients.¹ Re-exploration for bleeding worsens the patient’s prognosis with a 3- to 4-fold increase of mortality.¹ There are also significant increases in costs in patients with bleeding-related complications.¹⁴

Complications from Inadequate Hemostasis 

Inadequate surgical hemostasis may lead to transfusion and/or other bleeding-related complications.¹⁴ Failure to achieve hemostasis in cardiac surgery can, for example, lead to retained blood which, while difficult to quantify, can result in a variety of negative postoperative outcomes.¹⁶ 

Complications of Retained Blood in the Chest Following Cardiac Surgery: 

• Development of cardiac tamponade¹⁶ 
• Low cardiac output¹⁶ 
• Chronic pleural effusions¹⁶ 
• Extended or prolonged monitoring in the intensive care unit¹⁶ 
• Prolonged drainage with chest tubes which can result in increased postoperative pain and the need for narcotics¹⁶ 
• Potential delay in post-operative extubation while monitoring bleeding which can result in a variety of issues and complications from prolonged mechanical ventilation¹⁶ 
• Mediastinitis¹⁶ 
• Acute pericarditis with associated/confounding electrocardiogram changes and/or arrhythmias¹⁶ 
• Long-term development of constrictive pericarditis^{16, 17}  

Unless coagulopathy is present, bleeding starts with vessel interruption. If surgical repair occurs in a reasonable period of time, the bleeding is contained, and hemostasis is secured, no additional action is needed.² If repair is delayed, clotting may still occur, but more often, the clots formed are dislodged and bleeding continues or recurs.²  

With sustained bleeding, coagulation factors are consumed and hemodilution, hypothermia, and acidosis compound factor consumption and lead to more bleeding.² The consequences for cellular perfusion and oxygenation of untreated hemorrhage and hypovolemia are well known and recommendations regarding resuscitation are based on the need to maintain adequate cellular perfusion.²  

Guidelines aimed at improving the management of perioperative coagulopathic bleeding in cardiac surgery recommend the use of point-of-care (POC) hemostatic testing within the context of integrated transfusion algorithms.^20,21 Compared with standard hemostatic tests, POC tests have faster turnaround times and better ability to identify specific coagulation defects, thereby allowing for targeted and more rapid management of coagulopathic bleeding.²¹ 

Common Methods of Achieving Hemostasis   

Surgeons and operating room staff employ various strategies to achieve hemostasis.²² These include mechanical methods (such as sutures and clips), thermal techniques (like electrocautery), and the application of topical hemostatic agents consisting of mechanical, active, flowable, and fibrin sealants.²² The choice of method depends on the specific surgical context and source of bleeding.   

Hemostasis and the Prevention of Severe or Massive Bleeding in Cardiovascular Surgery  

Coagulopathy associated with cardiac surgery is a multifactorial serious complication that may result in massive bleeding requiring transfusion of red blood cells and procoagulant products to obtain adequate hemostasis.²³ Severe or massive hemorrhage in cardiac surgery is an infrequent but clinically significant event. ²⁴  Estimations vary considerably (2-10 %) depending on the definition of massive hemorrhage but are nevertheless associated with high mortality.²⁴

Failed or delayed treatment of a massive bleeding can result in irreversible end-organ damage (e.g., renal failure), cardiovascular events (e.g., stroke, myocardial injury) or death, accompanied by significantly increased costs.²⁴ In cardiac surgery, thromboelastometry and thromboelastography, as well as other POC methods of coagulation monitoring, have proven quite effective in predicting excessive hemorrhage, reducing perioperative bleeding, transfused blood products and associated morbidity.²⁴ 

Achieving Hemostasis: Techniques and Tools

Surgeons have an array of options to control bleeding, including mechanical and thermal techniques and devices as well as pharmacotherapies and topical agents.²⁵ Application of direct pressure or compression at a bleeding site is often the surgeon’s first choice to assist in the control of bleeding.²⁵ Other mechanical methods, including sutures, staples, and ligating clips, are useful if the source of bleeding is easily identifiable and able to be sealed.²⁵ Compression or other mechanical methods, however, may not be appropriate during all surgical procedures; for example in cardiac surgery with heparinized patients.²⁵ 

Topical Hemostatic Agents in Cardiovascular Surgery  

Absorbable topical hemostatic agents have since been developed and provide useful adjunctive therapy when conventional methods of hemostasis are ineffective or impractical.²⁵ Topical hemostatic agents can be applied directly to the bleeding site and may prevent continuous unrelenting bleeding throughout the entire procedure and into the postoperative recovery period.²⁵  

A number of topical hemostatic agents are currently available for use in surgery. They can be divided into two categories: those that provide their mechanism of action on the clotting cascade in a biologically active manner and those that act passively through contact activation and promotion of platelet aggregation (Figure 2).²⁵

Figure 2: Topical Hemostatic Agents³ 

Figure adapted from Iannitti et al³

Mechanical or passive hemostats form physical barriers that block blood flow and create thrombogenic surfaces, allowing blood to clot more rapidly.^3,26 They achieve hemostasis by using patients’ own circulating coagulation factors.^3,26 Therefore, they are optimal for patients with an intact coagulation system.^3,26 

Active products participate at the end of the coagulation cascade and bypass the initial steps of the clotting cascade.³ Thus, other aspects of the coagulation cascade can be dysfunctional without impacting product efficacy.³ Patients with coagulopathies from clotting factors, other than hypofibrinogenemia, platelet dysfunction, or those receiving antithrombotic medications may be ideal candidates for active hemostats.³ 

Baxter Healthcare understands that during cardiovascular surgery blood management is essential to saving lives and created its portfolio of products to address those needs.  Below are a few examples of how Baxter Healthcare products can address bleeding challenges. 

As with other hemostatic agents, do not aspirate Floseal Matrix into extra corporeal cardiopulmonary bypass circuits or autologous blood salvage circuits. It has been demonstrated that fragments of collagen based hemostatic agents may pass through 40 μm transfusion filters of blood scavenging systems.²⁸ 

In off-pump CABG surgeries, the heart continues to beat while the surgeon performs the bypass. This technique avoids the use of CPB and is beneficial for certain patients.²⁷ However, operating on a beating heart may present unique challenges, particularly in achieving effective hemostasis.

TISSEEL [fibrin sealant] Indications

Tisseel is a fibrin sealant indicated for use as an adjunct to hemostasis in adult and pediatric patients (> 1 month of age) undergoing surgery when control of bleeding by conventional surgical techniques (such as suture, ligature, and cautery) is ineffective or impractical. Tisseel [fibrin sealant] is effective in heparinized patients. Click here for Tisseel [fibrin sealant] full Indications, Important Risk Information and full Prescribing Information. 

Aortic Aneurysm Repair 

During an aortic aneurysm repair, sealants can work independently of the coagulation cascade to prevent bleeding.^32-36 

Summary and Conclusions 

Achieving effective hemostasis in cardiovascular surgery is paramount for ensuring patient safety.¹ This article has outlined the foundational knowledge necessary to understand the complexities of hemostasis, detailed the significance of meticulous bleeding control in cardiovascular procedures, and highlighted the innovative hemostatic agents from Baxter Healthcare. As the field of cardiovascular surgery continues to evolve, the focus on refining hemostatic practices remains critical, underscoring the importance of continuous education and adoption of evidence-based strategies to enhance patient care.