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Fulltext Blood pressure patterns and the prevalence of hypertension and its associated factors in a rural community in Northern Malaysia

Narayan, K.A., A Rashid, K.

Malaysian Journal of Public Health Medicine, 2007;7(1):14-19.
MyJurnal

This study was conducted to study the blood pressure pattern and the prevalence of hypertension and its associated factors in a rural community in two coastal villages in rural Kedah, Mahysia. Out of the total population 504 were above 20 years of age and were eligible to participate. There were 227 males and 252 females. The mean systolic blood pressure was found to rise with age, peaking in the 6l·70 years age group, For women the mean blood pressure rose earlier from the age group of 4-l· 50 years. Mean blood pressures rose with increasing body mass index. lt also varied with occupation and education. The retired and unemployed had a higher blood pressure than those employed and there was an inverse relationship with increasing education. The prevalence of hypertension was 33.6%. More females were hypertensive (36.5%) as compared to males (3 0.4%) and this finding was the same for both systolic and diastolic hypertension. Majority (71.4%) of the hypertensives were undiagnosed. 72.5% of hypertensives who were on treatment were not under control. Hypertension was more prevalent among retirees and illiterates. Prevalence of hypertension increased correspondingly with age. Obesity was associated with hypertension. There was no association with family history of hypertension. Multiple logistic regression showed a positive association only for obesity. ln conclusion, given the high prevalence of hypertension at
present, it appears that the prevalence will increase as each age cohort grows older. Obesity, especially among housewives is a significant assorted factor.

Matched MeSH terms: Systole
Fulltext Cardio-respiratory responsesto standardized load resistance training in recreationally active participants

Nur Ikhwan Mohamad, Rumpf, Michael C., Tan, Erik C.H., Abas, Nicholas Garaman

Movement Health & Exercise, 2015;4(1):15-26.
MyJurnal

This paper aims to determine acute responses of standardized resistance training load on cardio-respiratory variables in recreationally active participants. The methodology involved twelve recreationally active males with an age of 23.5 (± 4.07) years, a mass of 70.5 (± 7.84 kg), a height of 1.69 (± 0.06 m), and a body mass index of 24.8 (± 2.14) kg/m2). The participants performed an exercise protocol that comprises five exercises on a standardized load. Each exercise was performed in a duration of 60 seconds with uncontrolled lifting velocity. Cardio-respiratory responses were measured using a portable metabolic system analyzer during the exercises. A wrist digital blood pressure monitor was used to determine pre- and postprotocol blood pressure responses. Based on the results, pre- and postprotocol systolic (p=0.744) and diastolic (p=0.758) blood pressure indicated no significant responses. However, significant differences were observed in pre- and post-heart rate responses (p=0.000). Peak cardio-respiratory responses recorded during the protocol were 30.2 (± 4.02) ml/Kg/min for oxygen consumption, 138 (± 61.9) bpm for heart rate, and 633 (± 71.2) kcal for energy expenditure (estimated per hour). On average, the Metabolic Equivalent of Task (MET) was recorded at a value of 8.62 (± 1.19). For a short duration standardized load circuit training exercise protocol, cardio respiratory responses were similar to other protocols. The metabolic cost of the predefined exercises was nearly half of the recommended energy expenditure through exercise per week. The prescribed protocol was comparable with other exercise protocols for cardiorespiratory variables. The single set protocol used was efficient in terms of caloric expenditure, and was less strenuous over similar exercise duration. Furthermore, the prescribed protocol is applicable and beneficial for active and healthy individuals.

Matched MeSH terms: Systole
Association of insertion/deletion polymorphism of angiotensin-converting enzyme gene among Malay male hypertensive subjects in response to ACE inhibitors

Heidari F, Vasudevan R, Mohd Ali SZ, Ismail P, Etemad A, Pishva SR, et al.

J Renin Angiotensin Aldosterone Syst, 2015 Dec;16(4):872-9.
PMID: 25002132 DOI: 10.1177/1470320314538878

Several studies show that the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene has been associated with hypertension in various populations. The present study sought to determine the association of the I/D gene polymorphism among Malay male essential hypertensive subjects in response to ACE inhibitors (enalapril and lisinopril).

Matched MeSH terms: Systole
Fulltext What is next after transfer of care from hospital to home for stroke patients? Evaluation of a community stroke care service based in a primary care clinic

Aziz AF, Aziz NA, Nordin NA, Ali MF, Sulong S, Aljunid SM

J Neurosci Rural Pract, 2013 Oct;4(4):413-20.
PMID: 24347948 DOI: 10.4103/0976-3147.120243

CONTEXT: Poststroke care in developing countries is inundated with poor concordance and scarce specialist stroke care providers. A primary care-driven health service is an option to ensure optimal care to poststroke patients residing at home in the community.
AIMS: We assessed outcomes of a pilot long-term stroke care clinic which combined secondary prevention and rehabilitation at community level.
SETTINGS AND DESIGN: A prospective observational study of stroke patients treated between 2008 and 2010 at a primary care teaching facility.
SUBJECTS AND METHODS: Analysis of patients was done at initial contact and at 1-year post treatment. Clinical outcomes included stroke risk factor(s) control, depression according to Patient Health Questionnaire (PHQ9), and level of independence using Barthel Index (BI).
STATISTICAL ANALYSIS USED: Differences in means between baseline and post treatment were compared using paired t-tests or Wilcoxon-signed rank test. Significance level was set at 0.05.
RESULTS: Ninety-one patients were analyzed. Their mean age was 62.9 [standard deviation (SD) 10.9] years, mean stroke episodes were 1.30 (SD 0.5). The median interval between acute stroke and first contact with the clinic 4.0 (interquartile range 9.0) months. Mean systolic blood pressure decreased by 9.7 mmHg (t = 2.79, P = 0.007), while mean diastolic blood pressure remained unchanged at 80mmHg (z = 1.87, P = 0.06). Neurorehabilitation treatment was given to 84.6% of the patients. Median BI increased from 81 (range: 2-100) to 90.5 (range: 27-100) (Z = 2.34, P = 0.01). Median PHQ9 scores decreased from 4.0 (range: 0-22) to 3.0 (range: 0-19) though the change was not significant (Z= -0.744, P = 0.457).
CONCLUSIONS: Primary care-driven long-term stroke care services yield favorable outcomes for blood pressure control and functional level.

Matched MeSH terms: Systole
Fulltext Glycaemic Control, Lipid Profile, Blood Pressure and Body Weight Status Among Diabetics in Rural Malaysia

Hazizi, A.S., Zaitun, Y., Kandiah, M., Chan, S.P.

International Medical Journal Malaysia, 2009;8(2):21-28.
MyJurnal

Introduction: Diabetes is associated with a high risk of cardiovascular disease. The management of blood glucose, dyslipidaemia and other modifiable risk factor, is a key element in the multifactorial approach to prevent complications of type 2 diabetes. Materials and Methods: A cross sectional study was conducted to determine the level of glycaemic control, lipid profile, blood pressure and body weight status among type 2 diabetics in rural Malaysia. A total of 237 diabetic subjects participated in this study. Physical examination was carried out, including measurements of height, weight, waist and hip circumferences, and systolic and diastolic blood pressure. Fasting venous blood samples were collected to determine the glucose level and lipid profile. Results: About 70% of the subjects had a high body mass index (BMI), equal to or above 25 kg/m2. More than 60% of the subjects had systolic blood pressure >= 140 mmHg and/or diastolic >=90 mmHg. Mean fasting blood glucose was 9.84±4.54 mmol/L. Mean total cholesterol was 5.18±1.35 mmol/L. High density lipoprotein cholesterol (HDLC) and triglyceride (TG) and glucose levels were higher in male than in female, but not statistically significant (p>0.05). However, low density lipoprotein cholesterol (LDLC) was higher in females than males (p

Matched MeSH terms: Systole
Fulltext Isolated systolic hypertension in Asia

Tsai TY, Cheng HM, Chuang SY, Chia YC, Soenarta AA, Minh HV, et al.

J Clin Hypertens (Greenwich), 2021 03;23(3):467-474.
PMID: 33249701 DOI: 10.1111/jch.14111

Isolated systolic hypertension (ISH) is the most common type of essential hypertension in the elderly and young adults. With rapid industrialization and population aging, the prevalence of ISH in Asia will rise substantially. Asian populations have distinct epidemiological features, risk factors and are especially vulnerable to ISH. There is a pressing need for Asian countries to formulate their unique strategies for control of ISH. In this review, we focus on the (1) epidemiology and pathophysiology, (2) risk factors and impact on outcomes, and (3) treatment goal and strategy for ISH in Asia.

Matched MeSH terms: Systole
Fulltext Efficacy and tolerability of lercanidipine in mild to moderate hypertension among Asians of different ethnic groups

Chia YC, Yeoh ES, Ng CJ, Khoo EM, Chua CT

Singapore Med J, 2009 May;50(5):500-5.
PMID: 19495520

INTRODUCTION: Calcium channel blockers are well established modalities for the treatment of hypertension. However, in spite of the availability of many efficacious agents, hypertension control continues to be poor. One reason is poor tolerability due to adverse events. Racial differences also exist. Lercanidipine, a third-generation calcium channel blocker, is associated with better tolerability. However, it has not been studied in the Asian population. This study examines its efficacy and tolerability in Asian subjects of different ethnicities.
METHODS: This was an eight-week open label study of adults with mild to moderate hypertension. Blood pressure (BP), pulse rate, self-administered symptom check and laboratory evaluations were done at baseline. Patients were prescribed 10 mg lercanidipine, with up-titration to 20 mg if BP was not controlled at Week 4. Baseline evaluations were repeated at Week 8. Adverse events were also enumerated.
RESULTS: 27 patients (mean age 53.4 +/- 12.1 years) completed the study. The baseline systolic BP (SBP), diastolic BP (DBP) and heart rate was 159 +/- 12.2, 96.6 +/- 7.7 mmHg and 71 +/- 13/min, respectively. Three racial groups were represented. SBP and DBP decreased significantly after four weeks of therapy. A further reduction to 139 +/- 14.3 and 88 +/- 9.8 (p-value is less than 0.0001) was seen in Week 8. The absolute SBP and DBP reduction was 20.5 mmHg (95 percent confidence interval [CI] 16.5-24.5, p-value is less than 0.0001) and 9.3 mmHg (95 percent CI 6.2-12.5, p-value is less than 0.0001), respectively. All adverse symptoms, except for palpitations, were reduced at the end of the study.
CONCLUSION: Lercanidipine is efficacious and well tolerated in Asians of different ethnicities. Its BP lowering effects and tolerability in Asians appear to be similar to other studies on Caucasians and other calcium channel blockers.

Matched MeSH terms: Systole/drug effects
The role of infarct transmural extent in infarct extension: A computational study

Leong CN, Lim E, Andriyana A, Al Abed A, Lovell NH, Hayward C, et al.

Int J Numer Method Biomed Eng, 2017 Feb;33(2).
PMID: 27043925 DOI: 10.1002/cnm.2794

Infarct extension, a process involving progressive extension of the infarct zone (IZ) into the normally perfused border zone (BZ), leads to continuous degradation of the myocardial function and adverse remodelling. Despite carrying a high risk of mortality, detailed understanding of the mechanisms leading to BZ hypoxia and infarct extension remains unexplored. In the present study, we developed a 3D truncated ellipsoidal left ventricular model incorporating realistic electromechanical properties and fibre orientation to examine the mechanical interaction among the remote, infarct and BZs in the presence of varying infarct transmural extent (TME). Localized highly abnormal systolic fibre stress was observed at the BZ, owing to the simultaneous presence of moderately increased stiffness and fibre strain at this region, caused by the mechanical tethering effect imposed by the overstretched IZ. Our simulations also demonstrated the greatest tethering effect and stress in BZ regions with fibre direction tangential to the BZ-remote zone boundary. This can be explained by the lower stiffness in the cross-fibre direction, which gave rise to a greater stretching of the IZ in this direction. The average fibre strain of the IZ, as well as the maximum stress in the sub-endocardial layer, increased steeply from 10% to 50% infarct TME, and slower thereafter. Based on our stress-strain loop analysis, we found impairment in the myocardial energy efficiency and elevated energy expenditure with increasing infarct TME, which we believe to place the BZ at further risk of hypoxia. Copyright © 2016 John Wiley & Sons, Ltd.

Matched MeSH terms: Systole
Fulltext Piper sarmentosum Leaves Aqueous Extract Attenuates Vascular Endothelial Dysfunction in Spontaneously Hypertensive Rats

Hashim Fauzy F, Mohd Zainudin M, Ismawi HR, Elshami TFT

Evid Based Complement Alternat Med, 2019;2019:7198592.
PMID: 31485247 DOI: 10.1155/2019/7198592

Piper sarmentosum is a tropical plant in Southeast Asia known for its traditional use in curing various ailments including hypertension. Previous research works have provided evidence for the herb's antihypertensive property. However, the exact mechanisms involved are still in question. The present study investigated the effects of Piper sarmentosum leaves aqueous extract (PSAE) treatment on vascular endothelin system in spontaneously hypertensive rats (SHRs). Four groups of SHRs were treated for 28 consecutive days, with negative and positive control groups receiving distilled water and 3 mg/kg perindopril, respectively. Another two groups are the treatment groups, which received PSAE and combination of 1.5 mg/kg perindopril and PSAE. Weekly measurements of blood pressure showed that PSAE significantly reduced the systolic, diastolic, and mean arterial pressures (P < 0.05) of the rats. PSAE also increased mesenteric artery nitric oxide (NO) level (P < 0.05) and reduced endothelin-1 (ET-1) level (P < 0.05) in the treatment groups. Our results demonstrate that oral administration of PSAE reduced blood pressure in SHRs by reducing the ET-1 level while increasing NO production.

Matched MeSH terms: Systole
Effects of durian fruit on blood pressure of spontaneously hypertensive rats

Malina Jasamai, Nurul Hanis Samsudin, Norazrina Azmi, Endang Kumolosasi

Sains Malaysiana, 2018;47:1221-1226.

Durian or scientifically known as Durio zibethinus is one of the most well-known seasonal fruits in the Southeast Asia
region. However, its safe consumption in individuals with hypertension is still controversial. This study was conducted
to investigate the effect of durian on blood pressure of spontaneously hypertensive rat model. Four groups of rats (n=5)
were fed with either a low dose durian (26 g/kg), a high dose durian (52 g/kg), sugar solution (8 mL/kg) which has
similar sugar composition in the durian as placebo control, and distilled water as vehicle control (8 mL/kg) for 14 days.
The durian doses for rats were obtained by converting from human doses. Baseline reading of blood pressure and heart
rate were recorded before the first oral administration of durian. The blood pressure and heart rate were also measured
1 h after the durian oral administration on day 1, 3, 7 and 14 of the experiment. In conclusion, durian fruit possessed
an acute effect on the blood pressure of hypertensive rats but heart rate was unaffected. High dose administration of
durian led to significant elevation of blood pressure after 1 h of consumption. Meanwhile, low dose of durian (26 g/kg)
caused an insignificant reduction in systolic and diastolic blood pressure. Tolerance to the durian fruit was observed after
three to seven days of the oral administration and low dose consumption of durian fruit was safe in the hypertensive rat.

Matched MeSH terms: Systole
Prospective study to determine the effect of intermittent pneumatic foot and calf compression on popliteal artery peak systolic blood flow

Mokhtar S, Azizi ZA, Govindarajanthran N

Asian J Surg, 2008 Jul;31(3):124-9.
PMID: 18658010

OBJECTIVE: This study investigated the effects of posture and also intermittent foot and calf compression on peak systolic flow of the popliteal artery in a normal population.
METHODS: This was a prospective study carried out in normal subjects at the Vascular Laboratory, Department of Surgery, Hospital Kuala Lumpur, from March 2006 to September 2006. The study compared the popliteal artery blood flow during change of posture from the horizontal (supine) to the sitting position and the effect of intermittent pneumatic compression (IPC) of the foot and calf on popliteal artery blood flow immediately and 10 minutes after cessation of compression.
RESULTS: A total of 15 subjects involving 30 limbs were examined in this study. On comparing flows between the horizontal and sitting position, there was a mean reduction in blood flow of 23% (p < 0.005). Immediately after compression of the foot and calf, there was an increase in blood flow of between 4% and 35% with a mean of 15% (p < 0.05). Peak systolic flows at 10 minutes postcompression were 536 +/- 95 mL/min, which was still significantly higher than precompression measurements.
CONCLUSION: There is a significant reduction in popliteal artery blood flow on changing from the supine to the sitting position. Popliteal artery blood flow is higher than baseline after 15 minutes of intermittent pneumatic foot and calf compression. The increase in popliteal artery blood flow is still present 10 minutes after cessation of IPC.

Matched MeSH terms: Systole
MiD49 and MiD51: New mediators of mitochondrial fission and novel targets for cardioprotection

Samangouei P, Crespo-Avilan GE, Cabrera-Fuentes H, Hernández-Reséndiz S, Ismail NI, Katwadi KB, et al.

Cond Med, 2018 Aug;1(5):239-246.
PMID: 30338314

Acute myocardial infarction (AMI) and the heart failure (HF) that often follows are among the leading causes of death and disability worldwide. As such novel therapies are needed to reduce myocardial infarct (MI) size, and preserve left ventricular (LV) systolic function in order to reduce the propensity for HF following AMI. Mitochondria are dynamic organelles that can undergo morphological changes by two opposing processes, mitochondrial fusion and fission. Changes in mitochondrial morphology and turnover are a vital part of maintaining mitochondrial health, DNA stability, energy production, calcium homeostasis, cellular division, and differentiation, and disturbances in the balance of fusion and fission can predispose to mitochondrial dysfunction and cell death. Changes in mitochondrial morphology are governed by mitochondrial fusion proteins (Mfn1, Mfn2 and OPA1) and mitochondrial fission proteins (Drp1, hFis1, and Mff). Recent experimental data suggest that mitochondria undergo fission during acute ischemia/reperfusion injury (IRI), generating fragmented dysfunctional mitochondrial and predisposing to cell death. We and others have shown that genetic and pharmacological inhibition of the mitochondrial fission protein Drp1 can protect cardiomyocytes from acute IRI and reduce MI size. Novel components of the mitochondrial fission machinery, mitochondrial dynamics proteins of 49 kDa (MiD49) and mitochondrial dynamics proteins of 51 kDa (MiD51), have been recently described, which have been shown to mediating mitochondrial fission by targeting Drp1 to the mitochondrial surface. In this review article, we provide an overview of MiD49 and MiD51, and highlight their potential as novel therapeutic targets for treating cardiovascular diseases such as AMI, anthracycline cardiomyopathy, and pulmonary arterial hypertension.

Matched MeSH terms: Systole
Population differences in cardiovascular reactivity to the cold pressor test

Duncan MT, Husain R, Chen HM, Horvath SM

Am J Hum Biol, 1995;7(3):329-337.
PMID: 28557027 DOI: 10.1002/ajhb.1310070309

The interaction of race and climatic adaptation on patterns of cardiovascular reactivity among young adult males was examined. Malay and Chinese subjects living in a tropical climate in the Orient and Caucasians living in a sub-tropical climate in North America were investigated. The cold pressor test with hand immersion in cold water was used as the stressor. Systolic and diastolic blood pressures, cardiac frequency, cardiac output, and stroke volume were measured. The results provided limited evidence for absence of differences in cardiac reactivity among racial groups and for greater vascular reactivity in the Caucasians. Cold immersion also elicited differential responses which could be partially attributed to differences in acclimatizations status. © 1995 Wiley-Liss, Inc.

Matched MeSH terms: Systole
Systolic hypertension and duration of diabetes mellitus are important determinants of retinopathy and microalbuminuria in young diabetics

Wan Nazaimoon WM, Letchuman R, Noraini N, Ropilah AR, Zainal M, Ismail IS, et al.

Diabetes Res Clin Pract, 1999 Dec;46(3):213-21.
PMID: 10624787 DOI: 10.1016/s0168-8227(99)00095-9

This cross-sectional study looked at the prevalence of microalbuminuria and retinopathy in a cohort of 926 young, Type 1 and Type 2 diabetes mellitus (DM) patients, and determined the factors which were associated with these microvascular complications. The prevalence of microalbuminuria, defined as the albumin:creatinine ratio > or = 2.5 (for males) or > or = 3.5 mg/mmol (for females), was 13.4% in Type 1 DM, 69.5% in insulin-requiring Type 2 DM and 16% in Type 2 DM treated only with oral hypoglycemic agents. Compared to those with normal renal functions, these patients were older (P < or = 0.01), had significantly elevated blood pressures (P < 0.01 or P = 0.0001), and in the case of Type 1 DM, with a higher body mass index (P = 0.0001) and waist-hip ratio (P < 0.01). The prevalence of diabetic retinopathy in Type 1 DM was found to increase with the duration of diabetes, from 1.4% in the newly-onset (< 5 years), to 9.9% in those with 5-10 years disease, to 35% among patients with more than 10 years of diabetes (P < 0.0001). In this study, it was also observed that 10% of the Type 2 DM patients already had retinopathy within 5 years of diagnosis, and the prevalence increased significantly to 42.9% (P < 0.0001) among patients who had been diabetics for more than 10 years. Stepwise multiple regression analysis showed that besides the disease duration, systolic blood pressure was the most common and significant determinant for both microalbuminuria and retinopathy in both types of DM, thus implying that in order to reduce the risk of microvascular complications in diabetes mellitus, systolic and not just the diastolic blood pressure, should be effectively controlled.

Matched MeSH terms: Systole
Fulltext Hypertension control among euvolemic hypertensive hemodialysis patients in Malaysia: a prospective follow-up study

Khan A, Khan AH, Adnan AS, Sulaiman SAS, Mushtaq S, Ahmad N, et al.

J Pharm Policy Pract, 2019;12:10.
PMID: 31114693 DOI: 10.1186/s40545-019-0169-y

Objectives: Existing literature does not provide enough information on evaluation of factors associated with pre-dialysis controlled hypertension among euvolemic hemodialysis (HD) patients. We conducted a study to evaluate the rate and factors influencing pre-dialysis controlled hypertension among euvolemic HD patients.
Design: A multicenter prospective follow-up study.
Setting: Tertiary care teaching hospital and its associated private dialysis centers.
Participants: This study included 145 euvolemic eligible hypertensive patients. Various sociodemographic, clinical factors and drugs were investigated and analyzed by using appropriate statistical methods to determine the factors influencing hypertension control among the study participants.
Results: On baseline visit, the mean pre-dialysis systolic and diastolic BP (mmHg) of study participants was 161.2 ± 24. and 79.21 ± 11.8 retrospectively, and 30 (20.6%) patients were on pre-dialysis goal BP. At the end of the 6-months follow-up, the mean pre-dialysis systolic BP and diastolic BP (mmHg) of the patients was 154.6 ± 18.3 and 79.2 ± 11.8 respectively, and 42 (28.9%) were on pre-dialysis goal BP. In multivariate analysis, the use of calcium channel blockers (CCBs) was the only variable which had statistically significant association with pre-dialysis controlled hypertension at baseline (OR = 7.530, p-value = 0.001) and final (OR = 8.988, p-value

Matched MeSH terms: Systole
Fulltext Safety and Efficacy of Losartan 50 mg in Reducing Blood Pressure among Patients with Post-Dialysis Euvolemic Hypertension: A Randomized Control Trial

Aftab RA, Khan AH, Adnan AS, Sulaiman SAS, Khan TM

Sci Rep, 2017 12 18;7(1):17741.
PMID: 29255272 DOI: 10.1038/s41598-017-17437-4

The aim of current study was to assess the effectiveness of losartan 50 mg in reducing blood pressure among post-dialysis euvolemic hypertensive patients, observing their survival trends and adverse events during the course of study. A multicentre, prospective, randomised, single-blind trial was conducted to assess the effect of losartan 50 mg every other day (EOD), once a morning (OM) among post-dialysis euvolemic hypertensive patients. Post-dialysis euvolemic assessment was done by a body composition monitor (BCM). Covariate Adaptive Randomization was used for allocation of participants to the standard or intervention arm. Of the total 229 patients, 96 (41.9%) were identified as post-dialysis euvolemic hypertensive. Final samples of 88 (40.1%) patients were randomized into standard and intervention arms. After follow-up of 12 months' pre-dialysis systolic (p

Matched MeSH terms: Systole/drug effects
Effects of sevoflurane increments on left ventricular systolic long-axis performance during sevoflurane-remifentanil anesthesia for cardiovascular surgery

Kwon WK, Sung TY, Yu GY, Sidik H, Kang WS, Lee Y, et al.

J Anesth, 2016 Apr;30(2):223-31.
PMID: 26577248 DOI: 10.1007/s00540-015-2094-9

BACKGROUND: The direct impact of sevoflurane on intraoperative left ventricular (LV) systolic performance during cardiac surgery has not been fully elucidated. Peak systolic tissue Doppler velocities of the lateral mitral annulus (S') have been used to evaluate LV systolic long-axis performance. We hypothesized that incremental sevoflurane concentration (1.0-3.0 inspired-vol%) would dose-dependently reduce S' in patients undergoing cardiac surgery due to mitral or aortic insufficiency.
METHODS: In 20 patients undergoing cardiac surgery in sevoflurane-remifentanil anesthesia, we analyzed intraoperative S' values which were determined after 10 min exposure to sevoflurane at 1.0, 2.0, and 3.0 inspired-vol% (T1, T2, and T3, respectively) with a fixed remifentanil dose (1.0 μg/kg/min) using transesophageal echocardiography.
RESULTS: Linear mixed-effect modeling demonstrated dose-dependent declines in S' according to the end-tidal sevoflurane concentration increments (C(ET)-sevoflurane, p < 0.001): the mean value of S' reduction for each 1.0 vol%-increment of C(ET)-sevoflurane was 1.7 cm/s (95 % confidence interval 1.4-2.1 cm/s). Medians of S' at T1, T2, and T3 (9.6, 8.9, and 7.5 cm/s, respectively) also exhibited significant declines (by 6.6, 15.6, and 21.2 % for T1 vs. T2, T2 vs. T3, and T1 vs. T3, p < 0.001, =0.002, and <0.001 in Friedman pairwise comparisons, respectively).
CONCLUSIONS: Administering sevoflurane as a part of a sevoflurane-remifentanil anesthesia regimen appears to dose-dependently reduce S', indicating LV systolic performance, in patients undergoing cardiac surgery. Further studies may be required to evaluate the clinical implications of these findings.

Matched MeSH terms: Systole
The role of end-diastolic myocardial fibre stretch on infarct extension

Leong CN, Dokos S, Andriyana A, Liew YM, Chan BT, Abdul Aziz YF, et al.

Int J Numer Method Biomed Eng, 2020 01;36(1):e3291.
PMID: 31799767 DOI: 10.1002/cnm.3291

Myocardial infarct extension, a process involving the enlargement of infarct and border zone, leads to progressive degeneration of left ventricular (LV) function and eventually gives rise to heart failure. Despite carrying a high risk, the causation of infarct extension is still a subject of much speculation. In this study, patient-specific LV models were developed to investigate the correlation between infarct extension and impaired regional mechanics. Subsequently, sensitivity analysis was performed to examine the causal factors responsible for the impaired regional mechanics observed in regions surrounding the infarct and border zone. From our simulations, fibre strain, fibre stress and fibre stress-strain loop (FSSL) were the key biomechanical variables affected in these regions. Among these variables, only FSSL was correlated with infarct extension, as reflected in its work density dissipation (WDD) index value, with high WDD indices recorded at regions with infarct extension. Impaired FSSL is caused by inadequate contraction force generation during the isovolumic contraction and ejection phases. Our further analysis revealed that the inadequacy in contraction force generation is not necessarily due to impaired myocardial intrinsic contractility, but at least in part, due to inadequate muscle fibre stretch at end-diastole, which depresses the ability of myocardium to generate adequate contraction force in the subsequent systole (according to the Frank-Starling law). Moreover, an excessively stiff infarct may cause its neighbouring myocardium to be understretched at end-diastole, subsequently depressing the systolic contractile force of the neighbouring myocardium, which was found to be correlated with infarct extension.

Matched MeSH terms: Systole/physiology
Impact of myocardial infarction on intraventricular vortex and flow energetics assessed using computational simulations

Chan BT, Ahmad Bakir A, Al Abed A, Dokos S, Leong CN, Ooi EH, et al.

Int J Numer Method Biomed Eng, 2019 06;35(6):e3204.
PMID: 30912313 DOI: 10.1002/cnm.3204

Flow energetics have been proposed as early indicators of progressive left ventricular (LV) functional impairment in patients with myocardial infarction (MI), but its correlation with individual MI parameters has not been fully explored. Using electro-fluid-structure interaction LV models, this study investigated the correlation between four MI parameters: infarct size, infarct multiplicity, regional enhancement of contractility at the viable myocardium area (RECVM), and LV mechanical dyssynchrony (LVMD) with intraventricular vortex and flow energetics. In LV with small infarcts, our results showed that infarct appearance amplified the energy dissipation index (DI), where substantial viscous energy loss was observed in areas with high flow velocity and near the infarct-vortex interface. The LV with small multiple infarcts and RECVM showed remarkable DI increment during systole and diastole. In correlation analysis, the systolic kinetic energy fluctuation index (E') was positively related to ejection fraction (EF) (R2 = 0.982) but negatively correlated with diastolic E' (R2 = 0.970). Diastolic E' was inversely correlated with vortex kinetic energy (R2 = 0.960) and vortex depth (R2 = 0.876). We showed an excessive systolic DI could differentiate infarcted LV with normal EF from healthy LV. Strong flow acceleration, LVMD, and vortex-infarct interactions were predominant factors that induced excessive DI in infarcted LVs. Instead of causing undesired flow turbulence, high systolic E' suggested the existence of energetic flow acceleration, while high diastolic E' implied an inefficient diastolic filling. Thus, systolic E' is not a suitable early indicator for progressive LV dysfunction in MI patients, while diastolic E' may be a useful index to indicate diastolic impairment in these patients.

Matched MeSH terms: Systole
The role of regional myocardial topography post-myocardial infarction on infarct extension

Leong CO, Leong CN, Liew YM, Al Abed A, Aziz YFA, Chee KH, et al.

Int J Numer Method Biomed Eng, 2021 08;37(8):e3501.
PMID: 34057819 DOI: 10.1002/cnm.3501

Infarct extension involves necrosis of healthy myocardium in the border zone (BZ), progressively enlarging the infarct zone (IZ) and recruiting the remote zone (RZ) into the BZ, eventually leading to heart failure. The mechanisms underlying infarct extension remain unclear, but myocyte stretching has been suggested as the most likely cause. Using human patient-specific left-ventricular (LV) numerical simulations established from cardiac magnetic resonance imaging (MRI) of myocardial infarction (MI) patients, the correlation between infarct extension and regional mechanics abnormality was investigated by analysing the fibre stress-strain loops (FSSLs). FSSL abnormality was characterised using the directional regional external work (DREW) index, which measures FSSL area and loop direction. Sensitivity studies were also performed to investigate the effect of infarct stiffness on regional myocardial mechanics and potential for infarct extension. We found that infarct extension was correlated to severely abnormal FSSL in the form of counter-clockwise loop at the RZ close to the infarct, as indicated by negative DREW values. In regions demonstrating negative DREW values, we observed substantial fibre stretching in the isovolumic relaxation (IVR) phase accompanied by a reduced rate of systolic shortening. Such stretching in IVR phase in part of the RZ was due to its inability to withstand the high LV pressure that was still present and possibly caused by regional myocardial stiffness inhomogeneity. Further analysis revealed that the occurrence of severely abnormal FSSL due to IVR fibre stretching near the RZ-BZ boundary was due to a large amount of surrounding infarcted tissue, or an excessively stiff IZ.

Matched MeSH terms: Systole

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