Arrhythmias In Hypertensive Patients Research Articles

Pattern of Arrhythmia among Hypertensive Patients in South-South, Nigeria: A 24-H Ambulatory ECG (Holter ECG) Study

Background: Regular 12-lead electrocardiogram (ECG) often fail to detect cardiac conduction abnormalities. Among hypertensive patients, conduction irregularities such as atrial fibrillation and ventricular tachycardia are recognized occurrences and these can be intermittent or asymptomatic. This study aims to evaluate the conduction abnormalities identified among hypertensives by Holter ECG in a private medical facility in South-South, Nigeria. Methods: This is a retrospective study of five hundred and thirteen patients consisting of 255 males and 258 females Holter ECG who presented at a private medical facility from January 2015- December 2016. Holter ECG data was acquired using Schiller type (MT-101) Holter ECG Machine. Results: Out of the 370 hypertensive patients reviewed, with a mean age of 55.18 ±.14.78, 205(55.41%) had tachycardia, 180(48.65%) had bradycardia, 184(49.73%) had ventricular ectopics while 169(45.68%) had supraventricular ectopics. The most common clinical indication was palpitation 150 (40.54%). The most prevalent age group was 41-60 years; 230 (44.83%) as compared to other age groups in the study. Tachycardia was the most common type of arrhythmia among the subjects. There was a higher incidence of arrhythmias in the female subjects than in the male. Conclusion: Tachycardia and ventricular ectopics were the most common conduction abnormalities observed. Beta blockers and anti-arrhythmics would be helpful for optimization of cardiovascular care. Holter ECG is beneficial in describing and characterizing arrhythmias in hypertensive patients in this population therefore, further studies on larger populations and diverse disease conditions are advocated.

The relationship between epicardial adipose tissue thickness and arrhythmias in patients with hypertension: a 3.0T cardiac magnetic resonance study.

To investigate the relationship between epicardial adipose tissue (EAT) thickness using cardiac magnetic resonance imaging (CMR) and arrhythmias in hypertensive patients. Fifty-four hypertensive patients with arrhythmias (HTN [arrhythmias+]), 79 hypertensive patients without arrhythmias (HTN [arrhythmias-]), and 39 normal controls were retrospectively enrolled. EAT thickness was measured on cine images. Analysis of covariance with Bonferroni's post hoc correction, Pearson or Spearman analysis, receiver operating characteristic curve, and intraclass correlation coefficient analysis were performed. All hypertensive patients had impaired left ventricular (LV) and left atrial (LA) myocardial deformation, and HTN (arrhythmias+) patients displayed higher LV myocardial native T1, LA volume index, and increased EAT thickness than HTN (arrhythmias-) patients and normotensive controls. The presence of LV late gadolinium enhancement (LGE) was higher in hypertensive patients with arrhythmias than in those without arrhythmias. EAT thickness metrics significantly correlated with age, systolic blood pressure, body mass index, triglycerides and high-density lipoprotein levels, LV mass index and native T1 (all p < 0.05). EAT thickness parameters were able to differentiate hypertensive patients with arrhythmias from those without arrhythmias and normal controls, and the right ventricular free wall had the highest diagnostic performance. An accumulation of EAT thickness could further induce cardiac remodeling, promote myocardial fibrosis, and exaggerate function in hypertensive patients with arrhythmias. CMR-derived EAT thickness metrics could be a useful imaging marker for differentiating hypertensive patients with arrhythmias, which might be a potential target for the prevention of cardiac remodeling and arrhythmias.

PLAUSIBLE CONFOUNDING FACTORS INFLUENCING ASSOCIATION OF LEFT VENTRICULAR HYPERTROPHY WITH VENTRICULAR LATE POTENTIALS IN HYPERTENSIVE PATIENTS

Background: Ventricular late potentials (VLPs) are low amplitude, high frequency signals which are remarkable non-invasive electrocardiographic markers of myocardial tissue damage which can be used to identify ventricular arrhythmias in hypertensive patients with left ventricular hypertrophy (LVH). There are significant confounding factors which affect the association of LVH with VLPs in hypertensive patients. Noteworthy among these are gender, age, body surface area (BSA) and smoking. This study was planned to observe the effect of these confounders on VLPs in hypertensive patients with LVH. Methods: The study was conducted in Department of Cardiac Electrophysiology, Armed Forces Institute of Cardiology, Rawalpindi from Nov 2019 to Nov 2020. This was a cohort retrospective study in which 64 patients with systemic arterial hypertension on the basis of LVH were divided into two equal groups. Patients meeting inclusion criteria were selected for Signal-Averaged ECG (SAECG). Results: Out of 64 patients, 49 (76.6%) were males and 15 (23.4%) were females. The overall mean age was 60±11.80 years. To rule out the effect of probable confounders (gender, age, BSA, and smoking) which predominantly affects VLPs in hypertensive patients with LVH, logistic regression was applied. Significance of association of LVH with VLPs increased from 0.01 to 0.03 reflecting that confounder, i.e., age, gender, BSA, and smoking were actually having a negative effect on association of VLPs with LVH. Conclusion: None of the confounders were associated with VLPs reflecting negative effect on association for the two variables of interest. Pak J Physiol 2023;19(1):3-4

Frequency of Cardiac Arrhythmias in Hypertensive Patients

Objective: To determine the frequency of cardiac arrhythmias in hypertensive patients.&#x0D; Study Design: Analytical Cross -sectional study.&#x0D; Place &amp; Duration of Study: Tertiary Cardiac Center, Lahore Pakistan from Jan 2021 to Dec2021.&#x0D; Methodology: Two hundred patients (males and females), age between 20-80 years, suffering from hypertensive disease (Blood Pressure ≥ 140/90mmHg), one year before were assessed in the study. After that ECG was done according to International standards. Then patients undergone 24 hour Holter monitoring test. Presence of cardiac arrhythmia was confirmed by the interpretation of 12 lead ECG and 24 hour Holter report. All the data was noted. Patients with cardiac arrhythmias were treated in consultation from the Electrophysiology (EP) department of the hospital. By using the SPSS version 26, the statistical data was tabulated, analyzed and interpreted.&#x0D; Results: The mean age was calculated to be 58.64±7.74 years. In this study the males were 148(74%) while 52(26%) were females. The mean duration of hypertension was found to be 5.09±1.56 years. Cardiac arrhythmias were noted in 22(11%) cases. Out of 22 cases of cardiac arrhythmias, 02(1%) patients had premature atrial contractions, 02(1%) had atrial flutter, 04(2%) had premature ventricular contractions and 14(7%) had atrial fibrillation. Cardiac arrhythmias were significantly higher in patients above 40 years of age (p&lt;0.05). There was no difference in both genders as well as duration of hypertension has unremarkable effect on cardiac arrhythmias (p&gt;0.05).&#x0D; Conclusion: The research study concluded that in hypertensive patients, the cardiac arrhythmias frequency is low but its value is not unremarkable.

Arrhythmia related to hypertensive left ventricular hypertrophy in Iraqi patients: frequency and outcome.

Left ventricular hypertrophy (LVH) caused by high blood pressure is linked to increased mortality and arrhythmia risk. This study aimed to evaluate arrhythmia in hypertensive patients due to left ventricular hypertrophy (LVH). A cross-sectional study was performed, assessing participants' blood pressure, echocardiography and electrocardiography, and Holter monitoring in certain cases. There were 300 hypertensive patients >18 years attending the cardiology unit of Baghdad medical city. The study was conducted between January-June 2022. The electrocardiograms at rest for 300 adults with hypertension were investigated. 130 (43.5%) were females, and 170 (56.5%) were males. The mean age of participants was 58 years. Forty-nine (16.3%) patients had arrhythmia. As compared to those without arrhythmia, participants with arrhythmia were older (62.3 vs. 56.1, p=0.03), had a greater prevalence of left ventricular hypertrophy (24.5% vs. 12.7%, p=0.026), and more prone to experience cardiac failure (32.7% vs. 8.5%, p<0.011). Atrial fibrillation was found in 6 (27.2%) female patients and 5 (18.5%) males. In addition, two (7.4%) male patients and one female patient (4.5%) had atrial flutter, and premature ventricular contractions (PVCs) were noted in 10 (37%) and 11 (50%) patients. Left ventricular mass index (LVMI) was 103 gm/m2 in female patients and 119.2 gm/m2 in males. Palpitation was present in 22 (44.9%) female patients and 27 (55.1%) males. The study revealed that hypertensives with LVH have an arrhythmia frequency of 16.3%. The most common arrhythmias were atrial fibrillation and premature ventricular complex.

SYNERGISTIC EFFECT OF HIGH HOMOCYSTEINE AND LOW VITAMIN B12 LEVELS ON THE PREVALENCE OF ATRIAL FIBRILLATION IN HYPERTENSIVE PATIENTS

Objective: Atrial fibrillation (AF) is common arrhythmia in hypertensive patients. Besides hypertension, several other conditions are deemed to be associated with AF. High blood homocysteine levels (hyperhomocysteinemia) is a known risk factor for cardiovascular disease and are associated with vitamin B12 deficiency that possibly increase cardiovascular risk, as well. The present study assessed the possible effect of high homocysteine and low B12 levels on AF prevalence in hypertensive patients. Design and method: This retrospective study comprised all hypertensives referred to our institutions and had a blood sample measurement of homocysteine and B12 (n = 32800). The presence of sustained AF (SAF; Long-standing/Persistent or Permanent AF) was recorded with a resting electrocardiogram (ECG). Paroxysms of AF (PAF) were confirmed with previous relevant ECGs provided by the patient. The population was divided in quartiles according to homocysteine levels (groups 1, 2, 3 and 4 for increasing levels) and B12 levels (groups 1, 2, 3 and 4 for decreasing levels). The prevalence of AF (SAF and PAF) was calculated for each homocysteine and B12 quartile group as well as for each of the 16 homocysteine/B12 combination quartile subgroups. Results: The mean values for homocysteine were 13.3 ± 7.2 ?mol/l and for B12 525 ± 196 pg/ml. The prevalence of SAF, PAF and all-type AF (SAF and PAF) was 5.0%, 6.1% and 11.1%, respectively. For homocysteine quartiles 1, 2, 3, 4, SAF prevalence was 2.9%, 5.3%, 11.7%, 24.3% (pfor trend 0.049), PAF prevalence was 0.6%, 0.9%, 4.6%, 14.0% (pfor trend 0.090) and all-type AF prevalence was 3.2%, 5.4%, 11.5%, 22.2% (pfor trend 0.051), respectively. For B12 quartiles 1, 2, 3, 4, SAF prevalence was 2.9%, 6.4%, 11.0%, 20.2% (pfor trend 0.030), PAF prevalence was 2.5%, 5.1%, 7.7%, 9.0% (pfor trend 0.009) and all type-AF prevalence was 2.4%, 7.1%, 16.8% 21.0% (pfor trend 0.019), respectively. The synergistic effect of increasing homocysteine and decreasing B12 values on SAF, PAF and all-type AF prevalence is presented in Figure. Conclusions: High homocysteine levels and low vitamin B12 levels are individually and synergistically associated with the prevalence of AF in hypertensive individuals. Underlying mechanisms merit further examination.

Hypertension and Arrhythmias: A Clinical Overview of the Pathophysiology-Driven Management of Cardiac Arrhythmias in Hypertensive Patients.

Because of demographic aging, the prevalence of arterial hypertension (HTN) and cardiac arrhythmias, namely atrial fibrillation (AF), is progressively increasing. Not only are these clinical entities strongly connected, but, acting with a synergistic effect, their association may cause a worse clinical outcome in patients already at risk of ischemic and/or haemorrhagic stroke and, consequently, disability and death. Despite the well-known association between HTN and AF, several pathogenetic mechanisms underlying the higher risk of AF in hypertensive patients are still incompletely known. Although several trials reported the overall clinical benefit of renin–angiotensin–aldosterone inhibitors in reducing incident AF in HTN, the role of this class of drugs is greatly reduced when AF diagnosis is already established, thus hinting at the urgent need for primary prevention measures to reduce AF occurrence in these patients. Through a thorough review of the available literature in the field, we investigated the basic mechanisms through which HTN is believed to promote AF, summarising the evidence supporting a pathophysiology-driven approach to prevent this arrhythmia in hypertensive patients, including those suffering from primary aldosteronism, a non-negligible and under-recognised cause of secondary HTN. Finally, in the hazy scenario of AF screening in hypertensive patients, we reviewed which patients should be screened, by which modality, and who should be offered oral anticoagulation for stroke prevention.

The Diagnostic Value of Combined 24-h BP and ECG Holter Monitoring in Detection of Cardiac Arrhythmias in Patients with Arterial Hypertension.

Background:Arrhythmias are common problems in hypertensive patients. The presence and complexity of both supraventricular and ventricular arrhythmias may influence morbidity, mortality, as well as the quality of life of patients.Objective:The aim of this study was to assess the diagnostic value of combined 24h BP and ECG Holter monitoring in detection of cardiac arrhythmias in patients with arterial hypertension.Methods:We analyzed the simultaneous records of combined 24h BP and ECG Holter monitoring for 356 adult patients with diagnosed arterial hypertension in the period from January 2017 until January 2021 year. The cardiac arrhythmias were classified in three main groups as following: a) Supraventricular arrhythmias; b) Ventricular arrhythmias; c) Bradyarrhythmia’s. Standard transthoracic echocardiograms were performed in order to evaluate signs of hypertensive or structural heart disease with focus on left ventricle hypertrophy and LV function.Results:Patients had a mean age of 64 ± 11years, 62% male. Average clinic BP was 153.4+18/87.5+14 mmHg. More than 46% of patients displayed a very high-risk profile. In all enrolled patients, cardiac arrhythmia was detected in 302 (84%) patients. The total number of patients with supraventricular arrhythmias was 153 (50,7%). Ventricular arrhythmias were detected in 98 (32,5%) patients. Bradyarrhythmia’s were detected in 51 (16,9%) patients. Elevated resting heart rate in sinus rhythm was detected in 87 (31,6%) of 275 patients with sinus rhythm.Conclusion:Most arrhythmias are related to longstanding arterial hypertension. Effective treatment of arterial hypertension plays important role in preventing structural and functional cardiac abnormalities which will contribute to the reduction of cardiac arrhythmias in hypertensive patients.

Hipertansiyon Hastalarında Sistolik Kan Basıncı Değişkenliği ve Kardiyovasküler Riskin Vekil Belirteçleri Arasındaki İlişki

Objective: Systolic blood pressure variability (SBPV) is a measure of oscillations in SBP for 24 hours. There are conflicting data about the relationship between SBPV and cardiovascular (CV) diseases. In this study, we aim to document a relationship between SBPV and surrogate markers of CV damage in a hypertensive patient cohort.&#x0D; Methods: Previously documented hypertension patients were enrolled. Patients with previously documented CV disease, diabetes mellitus and secondary hypertension were excluded. 24-hour ambulatory blood pressure monitoring (ABPM), echocardiography, electrocardiography and cardio-ankle vascular index (CAVI) measurements were performed. SBPV is defined as the standard deviation of mean systolic blood pressure readings from ABMP records. The relationship between SBPV and QTc distance, QT dispersion, presence of fragmented QRS, CAVI results were examined.&#x0D; Results: 64 patients were enrolled mean age 508, 24(37%) were male]. Mean SBPV was 15.124.6 and there was not a significant correlation between SBPV CAVI, QTc measurements of the study patients but there was a significant positive correlation with QT dispersion values (28.615.2, p=0.004, p=0.354). When patients were divided into two categories as high SBPV and low SBPV, QT dispersion was consistently longer in high SBPV group (p=0.006).&#x0D; Conclusion: In hypertensive patients without documented CV disease and signs of hypertensive CV changes on clinical evaluation, SBPV is positively correlated with QT dispersion but high SBPV is not related with aortic stiffness according to CAVI results. These findings might be a sign of occult left ventricular fibrosis and high risk of arrhythmia in hypertensive patients with high SBPV.

P3563The influence of circadian patterand obstructive sleep apnean of blood pressure in nocturnal arrhythmias in hypertensive patients

Abstract Introduction There is growing evidence suggesting hypertension is related to the occurrence of arrhythmias. When occurring predominantly during the night, two potential entities commonly present in hypertensive patients could be related with increased arrhythmogenesis: (1) the lack of normal nocturnal dipping of blood pressure (BP) (non-dipping pattern of hypertension) or (2) obstructive sleep apnea (OSA). Thus, nocturnal arrhythmias (NAs) can identify hypertensive patients with OSA and/or non-dipping pattern, both related with adverse outcomes. Aims To determine if NAs are related with non-dipping hypertension, OSA or both. Methods We studied hypertensive patients who performed ambulatory blood pressure monitoring (ABPM) and also polysomnography and 24-hour Holter monitoring. Non-dipping pattern was considered when nocturnal BP reduction was inferior to 10%. Based on Holter monitoring, NAs were present when atrial fibrillation, frequent premature atrial contractions (PACs) (&gt;30 PACs/hour), runs of &gt;4 consecutive PACs, frequent premature ventricular contractions (PVCs) (&gt;30PVCs/hour) or runs of &gt;4 consecutive PVCs were present predominantly during sleeping hours. During polyssonography, apnoea/hypopnoea index (AHI) and oxygen saturation (SaO2) were analysed. Moderate to severe OSA was considered when AHI &gt;15. Results We studied 104 patients [median age 62 (54–70) years, 65% male): 42 (40%) had moderate to severe OSA (median AHI=11 (6–26), mean SaO2=94% (92–95)] and 64 (61%) were non-dippers. NAs occurred in 18 patients (17%) and they were independently associated with AHI (Odds Ratio (OR) for a one unit increase 1.04, 95% confidence interval (CI) 1.01–1.07, p=0.03) but not with SaO2 (OR 0.96, CI 0.78–1.19, p=0.73) nor non-dipping pattern (OR 1.23, CI 0.38–3.98, p=0.72). No interaction was found between OSA and non-dipping hypertension (p=0.35). In patients with dipping pattern (n=40), AHI was higher in NAs patients comparing with no NAs patients (median AHI 29 versus 10, p=0.04), while in those with non-dipping pattern (n=64), AHI was not statistically different between patients with and without NAs (21 versus 11, p=0.12) (figure). Figure 1 Conclusion In this population of hypertensive patients, the presence of NAs was associated with OSA severity (i.e AHI), but not with the non-dipping pattern of hypertension. The importance of obstructive events in arrhythmogenesis seemed to be more pronounced in dipping patients, suggesting the abnormal high blood pressure during the night may also have some impact on NAs in non-dipping patients. Overall, our results suggest that OSA screening should be considered when nocturnal arrhythmias are detected in hypertensive patients, but ABPM should not be forgotten since multiple mechanisms can be involved in nocturnal arrhythmogenesis.

CARDIOPROTECTIVE PROPERTIES OF LISINOPRIL: NEW POSSIBILITIES

Aim. To study the changes in the stiffness of the arterial wall, vasomotor function of the endothelium, and appearance of new cases of atrial fibrillation (AF) in patients with arterial hypertension with long-term treatment with lisinopril.Material and method. 66 hypertensive patients with cardiac sinus rhythm at the age of 48-64 years (mean age 58.4±4.2 years) were included into the study. They were randomized into 2 groups: patients of group 1 (n=35) were prescribed lisinopril or a combination of lisinopril with hydrochlorothiazide over the 5-year follow-up; patients of group 2 (control) did not receive angiotensin converting enzyme inhibitors or angiotensin II receptor blockers. The follow-up duration was from September 2010 until June 2016. It included telephone calls once every 3 months and annual clinical, instrumental and laboratory examination. The new-onset AF was identified by the 24-hour Holter ECG monitoring results and by patient symptom diaries.Results. New-onset AF was registered in 2 patients (6%) in the lisinopril group and in 4 patients (13%) from the control group (p=0.001) over the 5-year follow-up. Lisinopril significantly reduced AF incidence in hypertensive patients. The patients on lisinopril were found to have no significant changes in the left ventricular mass index and left atrial size according to echocardiography done after the 5-year follow-up whereas in the patients of control group both parameters increased significantly. Lisinopril contributed to the maintenance of endothelial vasodilator function and prevented increase in arterial wall stiffness.Conclusion. Long term lisinopril treatment was found to significantly reduce the AF incidence in hypertensive patients over the 5-year follow-up. Lisinopril demonstrated organoprotective properties throughout the cardiovascular disease continuum and can be recommended for primary prevention of arrhythmia in hypertensive patients.

Statins in Secondary Prevention of Atrial Fibrillation

Aim . To study the effect of atorvastatin on the progression of the arrhythmia in hypertensive patients with paroxysmal atrial fibrillation (AF) in the longterm follow-up. Material and methods. Patients with paroxysmal AF (n=65) were included into the study. The patients were divided into two groups depending on the level of lipid metabolism: group I (n=33) received atorvastatin (10-40 mg/day), and control group II (n=32) did not take statins. The duration of follow-up was 4 years. The evolution of the AF clinical course was evaluated by the number of arrhythmia episodes for 3 months. Increase in the frequency of paroxysms of AF over the past 3 months, the appearance of the long-standing persistent AF or permanent AF considered as the arrhythmia progression. Results . The increase in rate and duration of AF episodes was found in 14 (42%) patients of group I and in 13 (41%) patients of group II. Progression of AF was observed with equal frequency in groups I and II. The average value of arrhythmia progression was 10.5% per year in patients of group I and 10.3% in group II. Significant differences between groups in the progression of AF were not found (p=0.2). Conclusion. Atorvastatin in hypertensive patients with paroxysmal AF did not lead to a change in rate and duration of arrhythmia paroxysms. The average value of paroxysmal AF progression was comparable regardless of atorvastatin use.

Is there any influence of elevated diastolic blood pressure on ventricular arrhythmias in hypertensive patients with left ventricular hypertrophy?

Cardiologia CROATICA Objective: To investigate the prevalence of ventricular arrhythmias in a patient with isolated systolic hypertension (ISHT) and left ventricular hypertrophy (LVH) in comparison to patients with systolic and diastolic hypertension and LVH. Patients and Methods: 192 (87 men) patients with essential hypertension and LVH were divided into two groups: 98 patients with ISHT and 94 patients with systolic and diastolic hypertension. After discontinuing all medications for a period of 48 hours, the blood pressure was measured, electrocardiography, echocardiography, Holter monitoring and bicycle ergometry were performed. The number of ventricular arrhythmias was recorded. Antihypertensive drugs and the duration of previous treatment were taken into consideration. Results: Isolated systolic hypertension (systolic blood pressure >140 mmHg and diastolic blood pressure <90 mmHg) was recorded in 98 patients (51%), 47 men and 51 women (Table 1). The frequency of ventricular arrhythmias did not differ according to Lowns classification categories I-II and IIIIV in patients with and without isolated systolic hypertension (Table 2). There was no difference in the treatment duration between the groups (p=0.858), or in the type of the applied medication. We found 44% complex ventricular arrhythmias in patients with ISHT. No significant difference was found in the frequency of ventricular arrhythmias between the groups that were observed. Conclusions: No significant difference was found in the frequency of ventricular arrhythmias in patients with isolated systolic hypertension and LVH in comparison to patients with systolic and diastolic hypertension and LVH. Diastolic blood pressure does not seem to have any influence on the frequency of ventricular arrhythmias in such patients.

Markers of Arrhythmogenic Risk in Hypertensive Subjects

Hypertension is increasingly considered a strong and independent risk factor for supraventricular and ventricular arrhythmias. The presence and complexity of both supraventricular and ventricular arrhythmias influence morbidity, mortality, as well as the quality of life of patients. Diastolic dysfunction of the left ventricle, left atrial size and function, and left ventricular hypertrophy have been suggested as the foremost underlying risk factors for supraventricular and ventricular arrhythmias in hypertensive patients. In particular, the presence of hypertension is a risk for sudden death and this risk is higher in those with left ventricular hypertrophy. Moreover, arrhythmias in the hypertrophic heart are often facilitated and aggravated by electrolyte disturbances, sympatho-vagal unbalance, transient blood pressure peaks, and occurrence of myocardial ischaemia. Several noninvasive biohumoral, electrocardiographic and imaging parameters have been widely investigated to identify hypertensive patients at higher risk for the development of arrhythmias. These parameters include neurohormones, signal averaged analysis of P wave, QT interval dispersion, heart rate variability, ventricular late potentials and T wave morphology analysis, as well as echocardiographic and magnetic resonance indexes of atrial and ventricular shape and function. The aim of this review is to evaluate the relationship of high blood pressure with ventricular and supraventricular arrhythmias, to discuss the available biomarkers for arrhythmic risk assessment in hypertensive patients and the effects of a tailored tight blood pressure control on the occurrence of arrhythmias.

Chamber‐specific effects of hypokalaemia on ventricular arrhythmogenicity in isolated, perfused guinea‐pig heart

Diuretic-induced hypokalaemia has been shown to promote cardiac arrhythmias in hypertensive patients. The present study was designed to determine whether hypokalaemia increases arrhythmic susceptibility of the left ventricle (LV) or the right ventricle (RV), or both. Proarrhythmic effects of hypokalaemic perfusion (2.5 mm K(+) for 30 min) were assessed in isolated guinea-pig heart preparations using simultaneous recordings of volume-conducted electrocardiogram and monophasic action potentials from six ventricular epicardial sites. Effective refractory periods, ventricular fibrillation thresholds and inducibility of tachyarrhythmias by programmed electrical stimulation and tachypacing were determined at the LV and the RV epicardial stimulation sites. Hypokalaemia promoted spontaneous ventricular ectopic activity, an effect attributed to non-uniform prolongation of ventricular repolarization resulting in increased RV-to-LV transepicardial dispersion of refractoriness and action potential duration. Furthermore, hypokalaemic perfusion was associated with reduced ventricular fibrillation threshold and increased inducibility of tachyarrhythmias by programmed electrical stimulation and tachypacing as determined at the LV stimulation site. In contrast, the RV stimulation revealed no change in arrhythmic susceptibility of the RV chamber. Consistently, hypokalaemia reduced the LV effective refractory period but had no effect on the RV refractoriness. This change enabled generation of premature propagating responses by extrastimulus application at earlier time points during LV repolarization. Increased prematurity of extrastimulus-evoked propagating responses was associated with exaggerated local inhomogeneities in intraventricular conduction and action potential duration in hypokalaemic LV, thus creating a favourable stage for re-entrant tachyarrhythmias. Taken together, these findings suggest that proarrhythmic effects of hypokalaemia are mostly attributed to increased LV arrhythmogenicity in the guinea-pig heart.

Effects of Angiotensin II on the Action Potential Durations of Atrial Myocytes in Hypertensive Rats

Angiotensin II (Ang II) has been reported to indirectly influence atrial electrical activity and to play a critical role in atrial arrhythmias in hypertensive patients. However, it is unclear whether Ang II has direct effects on the electrophysiological activity of the atrium affected by hypertension. We examined the effects of Ang II on the action potentials of atrial myocytes enzymatically isolated from spontaneous hypertensive rats (SHRs). The action potentials were recorded by the perforated patch-clamp technique and the atrial expression of the receptors AT1a and AT2 was measured by radioimmunoassay. Ang II significantly shortened the action potential durations (APDs) of SHRs without changes in the resting membrane potentials (RMPs). Pretreatment with selective AT1a blockers abolished the Ang II-induced reduction of atrial APDs of SHRs; however, a selective AT2 blocker did not, which was consistent with the results of the receptor assay. Pretreatment with phosphatidylinositol 3 (PI3)-kinase inhibitor, phospholipase C inhibitor, or protein kinase C (PKC) inhibitor abolished the Ang II-induced shortening of atrial APDs, but pertussis toxin and protein kinase A (PKA) inhibitor did not. To study the effects of chronic AT1a inhibition on Ang II-induced shortening of atrial APD, SHRs were treated with AT1a blocker for 4 weeks. AT1a blocker abolished the Ang II-induced reduction of atrial APDs of SHRs and also significantly lowered their blood pressure. In conclusion, Ang II shortened atrial APDs of SHRs via AT1a coupled with the Gq-mediated inositol triphosphate (IP3)-PKC pathway. Our findings indicated that Ang II caused atrial arrhythmias in hypertensive patients by shortening the effective refractory period of the atrium.

Toward the biochemical assessment of myocardial fibrosis in hypertensive patients

The serum concentrations of amino-terminal procollagen type III and carboxy-terminal procollagen type I-derived peptides, which have been proposed as useful markers of the tissue synthesis of collagen types III and type I, respectively, were abnormally increased in patients with essential hypertension and became normal after angiotensin-converting enzyme (ACE) inhibition. An association was found between baseline serum concentrations of these peptides and left ventricular hypertrophy, diastolic dysfunction, and ventricular arrhythmias in hypertensive patients. On the other hand, increased serum concentration of the carboxy-terminal procollagen type I-derived peptide was found in spontaneously hypertensive rats compared with normotensive Wistar-Kyoto control rats. An association was found between the serum concentration of this peptide and the extent of myocardial fibrosis and the hydroxyproline concentration in the left ventricle of spontaneously hypertensive rats. It is proposed that procollagen-derived peptides in serum may be markers of exaggerated collagen tissue synthesis involved in hypertensive myocardial fibrosis.

Relationship between Autonomic Function and Arrhythmia in Hypertensive Patients with Left Ventricular Hypertrophy

Relationship between Autonomic Function and Arrhythmia in Hypertensive Patients with Left Ventricular Hypertrophy

Comparison of diastolic left ventricular filling and cardiac dysrhythmias in hypertensive patients with and without isolated septal hypertrophy

Although many patients with hypertension develop isolated septal hypertrophy (ISH) rather than concentric or eccentric left ventricular (LV) hypertrophy, limited data are available on cardiac structure, function, and arrhythmias in hypertensive patients with ISH. Clinical features, hemodynamics, M-mode echocardiograms, and 24-hour electrocardiographic recordings were evaluated in 21 healthy normotensive subjects, 23 hypertensive patients without LV hypertrophy, 31 hypertensive patients with concentric LV hypertrophy, and 23 hypertensive patients with ISH to determine the prevalence and complexity of cardiac arrhythmias and diastolic LV filling abnormalities. Age, sex, race, obesity indexes, preload, ejection fraction, and LV contractility were similar in all 4 groups, and arterial pressure and afterload were statistically similar in the 3 hypertensive groups. Left atrial emptying index (p < 0.01) and peak LV filling rate (p < 0.01), 2 indexes of diastolic LV filling, were significantly reduced in the 3 hypertensive groups compared with the normotensive group. The duration of rapid LV filling, however, was significantly prolonged only in hypertensive patients with concentric LV hypertrophy and ISH (p < 0.05) but not in hypertensive patients without LV hypertrophy. The prevalence (p < 0.001) and complexity (p < 0.001) of ventricular ectopic activity was also significantly increased to a similar degree in hypertensive patients with concentric LV hypertrophy and in those with ISH compared with normotensive subjects or hypertensive patients without LV hypertrophy. The prevalence and complexity of atrial ectopic activity was only increased significantly (p < 0.001) in those with ISH.

Study of late potentials and ventricular arrhythmias in hypertensive patients with normal electrocardiograms.

Although an increase in the occurrence of ventricular arrhythmias has been observed in hypertensive patients, some basic questions remain unresolved regarding the prevalence and the pathophysiology of these arrhythmias. The basic aims of this study were as follows: (1) to examine the incidence and severity of ventricular arrhythmias in a substantial number of hypertensive patients without electrocardiographic indications of hypertrophy; and (2) to examine the correlation between late potentials, hypertrophy, and ventricular arrhythmias in these patients. We studied 78 consecutive patients (31 men, 47 women), aged 60.5 +/- 7.8 years, with a history of hypertension but a normal electrocardiogram. All patients had an echocardiographic study, 24-hour ambulatory monitoring, exercise test, and signal-averaged electrocardiogram. The latter was analyzed using a 40- to 250-Hz filter and with a noise level < or = 0.3 microV. Of the 78 patients studied, 21 (26.9%) had severe ventricular arrhythmias, while 57 (73.1%) had either no ventricular ectopics or sporadic isolated ventricular extrasystoles. Left ventricular hypertrophy, defined by echocardiography, was found in 58 patients (74.3%), of which 16 (27.58%) had severe ventricular arrhythmias. Five (25%) of the 20 patients without hypertrophy also had severe ventricular arrhythmias (P = NS). Ventricular late potentials were recorded in 19 (24.5%) of the 78 patients. Of these, 11 (57.89%) had severe arrhythmias, while of the 59 patients without late potentials 10 (16.94%) had severe ventricular ectopic activity. In hypertensive patients without electrocardiographic signs of hypertrophy, the higher prevalence of ventricular arrhythmias does not appear to be related to left ventricular hypertrophy but is correlated with the existence of ventricular late potentials.