In this study, valvular disease was closely related to high hospitalization expenses and severe complications, such as high hospital mortality rate, postoperative acute medical diseases, and venous thrombosis. Compared with other valvular diseases, AS is positively associated with high death rates and high hospitalization expenses. However, it is only related to several acute medical complications, in contrast to other valvular diseases. In addition, there were only 204 cases of AS in the more than 800,000 hip replacement cases in 2005–2014, of which 165 were female patients. Most of the cases were not from an elective admission. Fifty-five cases had acute cardiac complications. There were 18, 3, and 39 cases of ARF, liver failure, and postoperative urinary tract infection, respectively. In contrast to the results of a study conducted in 2008, no adverse complications were observed in the 22 cases of joint replacement with AS during 1994–2005.[8]
In one study among the older adult population over the age of 75 years, the proportion of severe AS cases was 3.4%, and the population prevalence rate was 12%. Another study found that AS exponentially increases with age: 3.9% and 9.8% in those aged 70–79 years and 80–89 years, respectively.[9] However, in this study, AS only accounted for 0.03% before hip replacement surgery; this may be related to the fact that most patients who needed THA were low-income individuals. Additionally, it may reflect that AS patients were not welcomed by orthopedists or the contribution of AS to mortality and morbidity might have been ignored in the orthopedics department. Unlike developing countries, high-income countries have already recognized AS as the most important cause of death from VHD.[9]
A previous study showed that the near-term risk for pulmonary embolism may be increased by heart diseases not associated with a diagnosed peripheral vein thrombosis.[10] By contrast, VHD acted as the protective factor for pulmonary embolism of the hip replacement in this study. It might due to the fact that the doctors were fully prepared to deal with such patients. However, further studies are required to determine the detailed protective reason for valvular disease. Some studies have demonstrated that ARF after cardiac surgery is related to an insufficient renal blood flow.[11] In this study, among patients with valvular disease, hip replacement was also significantly related to ARF, which may further be related to a low blood flow. In such cases, more attention should be paid to blood creatinine levels of patients with valvular disease before hip arthroplasty, particularly those with renal impairments preoperatively.
Most of the patients with valvular disease are older adults with a poor cardiopulmonary reserve along with several medical comorbidities, such as pneumonia or acute pulmonary edema/failure, as in this study, which means higher cardiopulmonary complications rates followed by higher death rates during the perioperative period. Therefore, lung functions of these older adult patients undergoing hip replacement need to be considered. Furthermore, the anesthesia type needs to be considered. On the one hand, general anesthesia may cause difficulty in extubation or lung infection postoperatively, which may even lead to an increased risk of infection around the prosthesis. However, one study found no relationship between the type of anesthesia and pneumonia after THA.[12] On the other hand, if patients with valvular disease have low blood pressure, local anesthesia is advantageous in reducing the risk of intraoperative hypotension, which may result in further myocardial damage. Moreover, most patients are non-selectively admitted, and a preoperative preparation may be relatively insufficient, leading to an increased risk of perioperative complications.
Compared with valvular disease, AS had fewer postoperative complications. In contrast to other valvular diseases, AS has a significant association with acute hepatic failure. To date, no study has been conducted that clearly finds the progresses of acute liver failure (ALF) after a hip arthroplasty with valvular disease. Another study had shown that ALF is not caused by hypotension or shock. However, it is related to chronic hemorrhagic heart failure, which is followed by a reduced oxygen supply and portal hypertension. The combined effect results in ALF.[13][14] Of note, ALF is mainly caused by hepatic hemorrhage rather than low blood output. Nevertheless, hepatic hemorrhage is often associated with advanced VHD. Thus, it may be caused by heart failure, which is the most common end stage of AS, although there may also be other mechanisms awaiting discovery.
Despite some differences between AS and other valvular diseases, both significantly improve the hospitalization cost and length of stay. Therefore, more attention should be paid to VHD patients undergoing hip replacement.
Our study has several limitations. This study roughly revealed the impact of VHD on hip replacement. However, the specific effect of various types of valvular diseases other than AS on hip replacement remains to be discussed. In addition, the relatively small size of AS patients provided limited statistical power. Moreover, the severity of the different valvular diseases had been limited by the database.
In conclusion, VHD combined with hip replacement is becoming more common in individuals as life expectancy continues to rise. However, the treatment urgency of THA and BHA are unclearly defined, while AS and heart dysfunction are relative contradictions. This study may give a reference to patients with valvular disease undergoing hip replacement in the future and spark future studies regarding the impact of different valvular diseases on hip replacement patients.