Hiroaki Hiraiwa

Dr. Hiroaki Hiraiwa

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Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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26 April 2024 in Medicine
Verified
Journal Article
Open access
HHHiroaki Hiraiwa
Hiroaki Hiraiwa
DKDaisuke Kasugai
Daisuke Kasugai
TOTakahiro Okumura
Takahiro Okumura
TMToyoaki Murohara
Toyoaki Murohara
Sepsis is caused by the body’s dysregulated response to infection, which can lead to multiorgan injury and death. Patients with sepsis may develop acute cardiac dysfunction, termed septic cardiomyopathy, which is a global but reversible dysfunction of both sides of the heart. This narrative review discusses the mechanistic changes in the heart during septic cardiomyopathy, its diagnosis, existing treatment options regarding severity and course, and emerging treatment approaches. Although no standardized definition for septic cardiomyopathy exists, it is described as a reversible myocardial dysfunction that typically resolves within 7 to 10 days. Septic cardiomyopathy is often diagnosed based on electrocardiography, cardiac magnetic resonance imaging, biomarkers, and direct invasive and noninvasive measures of cardiac output. Presently, the treatment of septic cardiomyopathy is similar to that of sepsis, primarily focusing on acute interventions. Treatments for cardiomyopathy often include angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and diuretics. However, because of profound hypotension in sepsis, many cardiomyopathy treatments are contraindicated in patients with septic cardiomyopathy. Substantial efforts have been made to study the pathophysiological mechanisms and diagnostic options; however, the lack of a uniform definition for septic cardiomyopathy is challenging for physicians when considering treatments. Another challenge for physicians is that the treatment for septic cardiomyopathy has only focused on acute intervention, whereas the treatment for other cardiomyopathies has been provided on a long-term basis. A better understanding of the underlying mechanisms of septic cardiomyopathy may contribute to the development of a unified definition of the condition and novel treatment options.

18 May 2022 in Heart Failure Reviews
Verified
Journal Article
Open access
PDF file
HHHiroaki Hiraiwa
Hiroaki Hiraiwa
TOTakahiro Okumura
Takahiro Okumura
TMToyoaki Murohara
Toyoaki Murohara
Despite the number of available methods to predict prognosis in patients with heart failure, prognosis remains poor, likely because of marked patient heterogeneity and varied heart failure etiologies. Thus, identification of novel prognostic indicators to stratify risk in patients with heart failure is of paramount importance. The spleen is emerging as a potential novel prognostic indicator for heart failure. In this article, we provide an overview of the current prognostic tools used for heart failure. We then introduce the spleen as a potential novel prognostic indicator, before outlining the structure and function of the spleen and introducing the concept of the cardiosplenic axis. This is followed by a focused discussion on the function of the spleen in the immune response and in hemodynamics, as well as a review of what is known about the usefulness of the spleen as an indicator of heart failure. Expert insight into the most effective spleen-related measurement indices for the prognostication of patients with heart failure is provided, and suggestions on how these could be measured in clinical practice are considered. In future, studies in humans will be required to draw definitive links between specific splenic measurements and different heart failure manifestations, as well as to determine whether splenic prognostic measurements differ between heart failure classes and etiologies. These contributions will provide a step forward in our understanding of the usefulness of the spleen as a prognostic predictor in heart failure.

22 January 2021 in Heart and Vessels
Verified
Journal Article
Closed access
PDF file
HHHiroaki Hiraiwa
Hiroaki Hiraiwa
TOTakahiro Okumura
Takahiro Okumura
TKToru Kondo
Toru Kondo
TKToshiaki Kato
Toshiaki Kato
SKShingo Kazama
Shingo Kazama
TMToyoaki Murohara
Toyoaki Murohara

10 July 2024 in Heart Failure Reviews
Verified
Journal Article
Open access
PDF file
HHHiroaki Hiraiwa
Hiroaki Hiraiwa
YYYoshimitsu Yura
Yoshimitsu Yura
TOTakahiro Okumura
Takahiro Okumura
TMToyoaki Murohara
Toyoaki Murohara
Improvements in therapies for heart failure with preserved ejection fraction (HFpEF) are crucial for improving patient outcomes and quality of life. Although HFpEF is the predominant heart failure type among older individuals, its prognosis is often poor owing to the lack of effective therapies. The roles of the spleen and bone marrow are often overlooked in the context of HFpEF. Recent studies suggest that the spleen and bone marrow could play key roles in HFpEF, especially in relation to inflammation and immune responses. The bone marrow can increase production of certain immune cells that can migrate to the heart and contribute to disease. The spleen can contribute to immune responses that either protect or exacerbate heart failure. Extramedullary hematopoiesis in the spleen could play a crucial role in HFpEF. Increased metabolic activity in the spleen, immune cell production and mobilization to the heart, and concomitant cytokine production may occur in heart failure. This leads to systemic chronic inflammation, along with an imbalance of immune cells (macrophages) in the heart, resulting in chronic inflammation and progressive fibrosis, potentially leading to decreased cardiac function. The bone marrow and spleen are involved in altered iron metabolism and anemia, which also contribute to HFpEF. This review presents the concept of an interplay between the heart, spleen, and bone marrow in the setting of HFpEF, with a particular focus on extramedullary hematopoiesis in the spleen. The aim of this review is to discern whether the spleen can serve as a new therapeutic target for HFpEF.

28 August 2019 in ESC Heart Failure
Verified
Journal Article
Open access
PDF file
TKToru Kondo
Toru Kondo
SYSumio Yamada
Sumio Yamada
DTDaisuke Tanimura
Daisuke Tanimura
SKShingo Kazama
Shingo Kazama
TIToshikazu Ishihara
Toshikazu Ishihara
TMToyoaki Murohara
Toyoaki Murohara
Aims: In acute heart failure (AHF), immobilization is caused because of unstable haemodynamics and dyspnoea, leading to protein wasting. Neuromuscular electrical stimulation (NMES) has been reported to preserve muscle mass and improve functional outcomes in chronic disease. NMES may be effective against protein wasting frequently manifested in patients with AHF; however, whether NMES can be implemented safely without any adverse effect on haemodynamics has remained unknown. This study aimed to examine the feasibility of NMES in patients with AHF. Methods and results: Patients with AHF were randomly assigned to the NMES or control group. The intensity of the NMES group was set at 10–20% maximal voluntary contraction level, whereas the control group was limited at a visible or palpable level of muscle contraction. The sessions were performed 5 days per week since the day after admission. Before the study implementation, we set the feasibility criteria with following items: (i) change in systolic blood pressure (BP) > ±20 mmHg during the first session; (ii) increase in heart rate (HR) > +20 b.p.m. during the first session; (iii) development of sustained ventricular arrhythmia, atrial fibrillation (AF), and paroxysmal supraventricular tachycardia during all sessions; (iv) incidence of new-onset AF during the hospitalization period < 40%; and (v) completion of the planned sessions by >70% of patients. The criteria of feasibility were set as follows; the percentage to fill one of (i)–(iii) was ±20 mmHg or HR > +20 b.p.m. were observed in three cases in the NMES group (8.8%) and five in the control group (12.8%). New-onset arrhythmia was not observed during all sessions in both groups. During hospitalization, one patient newly developed AF in the NMES group (2.9%), and one developed AF (2.6%) and two lethal ventricular arrhythmia in the control group. Thirty-one patients in the NMES group (91%) and 33 patients in the control group (84%) completed the planned sessions during hospitalization. This study fulfilled the preset feasibility criteria. Conclusions: NMES is feasible in patients with AHF from immediately after admission.

4 April 2024 in American Journal of Cardiovascular Drugs
Verified
Journal Article
Open access
PDF file
HHHiroaki Hiraiwa
Hiroaki Hiraiwa
TOTakahiro Okumura
Takahiro Okumura
TMToyoaki Murohara
Toyoaki Murohara
In this comprehensive state-of-the-art review, we provide an evidence-based analysis of current drug therapies for patients with heart failure with preserved ejection fraction (HFpEF) in the acute and chronic phases with concurrent hypertension. Additionally, we explore the latest developments and emerging evidence on the efficacy, safety, and clinical outcomes of common and novel drug treatments in the management of HFpEF with concurrent hypertension. During the acute phase of HFpEF, intravenous diuretics, mineralocorticoid receptor antagonists (MRAs), and vasodilators are pivotal, while in the chronic phase, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers have proven effective in enhancing clinical outcomes. However, the use of calcium channel blockers in HFpEF with hypertension should be approached with caution, owing to their potential negative inotropic effects. We also explored emerging drug therapies for HFpEF, such as sodium–glucose co-transporter 2 (SGLT2) inhibitors, angiotensin receptor–neprilysin inhibitor (ARNI), soluble guanylate cyclase (sGC) stimulators, novel MRAs, and ivabradine. Notably, SGLT2 inhibitors have shown promise in reducing heart failure hospitalizations and cardiovascular mortality in patients with HFpEF, regardless of their diabetic status. Additionally, ARNI and sGC stimulators have demonstrated potential in improving symptoms, functional capacity, and quality of life. Nonetheless, additional research is necessary to pinpoint optimal treatment strategies for HFpEF with concurrent hypertension. Furthermore, long-term studies are essential to assess the durability and sustained benefits of emerging drug therapies. Identification of novel targets and mechanisms underlying HFpEF pathophysiology will pave the way for innovative drug development approaches in the management of HFpEF with concurrent hypertension.