Determinants of LV dP/dtmax and QRS duration with different fusion strategies in cardiac resynchronisation therapy

BackgroundWe designed this study to assess the acute effects of different fusion strategies and left ventricular (LV) pre-excitation/post-excitation on LV dP/dtmax and QRS duration (QRSd).MethodsWe measured LV dP/dtmax and QRSd in 19 patients having cardiac resynchronisation therapy (CRT). Two groups of biventricular pacing were compared: pacing the left ventricle (LV) with FUSION with intrinsic right ventricle (RV) activation (FUSION), and pacing the LV and RV with NO FUSION with intrinsic RV activation. In the NO FUSION group, the RV was paced before the expected QRS onset. A quadripolar LV lead enabled distal, proximal and multipoint pacing (MPP). The LV was stimulated relative in time to either RV pace or QRS-onset in four pre-excitation/post-excitation classes (PCs). We analysed the interactions of two groups (FUSION/NO FUSION) with three different electrode configurations, each paced with four different degrees of LV pre-excitation (PC1–4) in a statistical model.ResultsLV dP/dtmax was higher with NO FUSION than with FUSION (769±46 mm Hg/s vs 746±46 mm Hg/s, p<0.01), while there was no difference in QRSd (NO FUSION 156±2 ms and FUSION 155±2 ms). LV dP/dtmax and QRSd increased with LV pre-excitation compared with pacing timed to QRS/RV pace-onset regardless of electrode configuration. Overall, pacing LV close to QRS-onset (FUSION) with MPP shortened QRSd the most, while LV dP/dtmax increased the most with LV pre-excitation.ConclusionWe show how a beneficial change in QRSd dissociates from the haemodynamic change in LV dP/dtmax with different biventricular pacing strategies. In this study, LV pre-excitation was the main determinant of LV dP/dtmax, while QRSd shortens with optimal resynchronisation.

Worsening renal failure due to renal steal by aortoiliac bypass

Aortoiliac bypass surgery is the gold standard strategy for removing persistent ischaemia resulting from bilateral aortoiliac occlusive disease, a condition known as Leriche syndrome. However, the impact of aortoiliac bypass surgery on the blood flow of the renal artery is not fully understood. Here, we report a case of worsening renal failure caused by renal steal immediately after aortoiliac bypass for Leriche syndrome. The revascularisation of bilateral renal arteries dramatically improved the patient’s renal function and allowed us to discontinue both haemodialysis and diuretics. This case demonstrates that in rare instances, haemodynamic change induced by aortoiliac bypass surgery affects the arteries feeding other organs. Careful preoperative evaluation for the corresponding branches of the aorta is indispensable. Optimal revascularisation should be performed to avoid serious complications after aortoiliac bypass if the patient is at risk of developing critical ischaemia.

Effects of pretreatment with magnesium sulphate on suxamethonium induced complications during induction of general anaesthesia - A placebo controlled study

Background To administer general anaesthesia with controlled ventilation, laryngoscopy and endotracheal intubation is necessary.Suxamethonium is drug of choice but some side effects preclude its use. Pretreatment with Magnesium sulphate reduces suxamethonium induced complications. Objective To see the effects of pretreatment with magnesium sulphate on suxamethonium induced complications during induction of general anaesthesia. Methods A total number of sixty patients of ASA grade I and II were selected randomly as per inclusions and exclusions criteria , thirty in each group. Group- C is the control group and group-M-patients were received magnesium sulphate 60mg per kg. Pulse rate, blood pressure, SPO2, ECG, Serum K+ concentration, fasciculation, myalgia and side effects of magnesium sulphate were recorded. Results Suxamethnium induced complications like fasciculation, raised potassium concentration, haemodynamic change during intubation and post operative myalgia significantly reduced in patients pre treated with magnesium sulphate. Conclusion Pretreatment with magnesium sulphate reduces incidence of suxamethonium induced complications during induction of general anaesthesia. DOI: http://dx.doi.org/10.3329/jbsa.v26i1.19813 Journal of Bangladesh Society of Anaesthesiologists 2013; 26(1): 27-32

OXYTOCIN IV BOLUS VS INFUSION;

Introduction: Obstetric texts advocate the use of oxytocin, either intramuscularly or as a dilute infusion, but warn against the useof intravenous bolus oxytocin, fearing significant maternal hemodynamic consequences. Objective: To compare the hemodynamic effects ofoxytocin given intravenous bolus versus infusion form. Study design: Randomized clinical trial. Setting: Study was conducted in mainoperation theatre and OPD of Combined Military Hospital, Rawalpindi. Duration of study: Study was carried out over a period of six monthsfrom 24-03-2009 to 23-09-2009. Subjects and methods: Total 138 patients were included in this study. Patients were divided into two groups(Group-A received oxytocin as bolus of 5 iu given as quickly as possible (approximately over 1 s) and in group-B 5 iu diluted to 20ml normalsaline given over 5 minute using an infusion pump). Each group comprised of 69 patients. Results: Mean age of the patients in group-A was27.3±1.8 and in group-B, 26.9±1.7. Heart rate (beast/min) effect of oxytocin given intravenous bolus vs infusion showed statistically significantdifference from 1 minute to 15 minute (P<0.001). Similarly mean arterial pressure (MAP) rate (beast/min) effect of oxytocin given intravenousbolus vs infusion also showed statistically significant difference from 1 minute to 15 minute (P<0.001). Conclusions: In conclusion, we foundthat at elective Caesarean section, 5 iu of i.v. oxytocin results in less haemodynamic change than 5 iu diluted to 20ml normal saline given over 5min using as an infusion pump.

Serial Haemodynamic Change In Children With Acute Empyema

Empyema thoracis continues to remain a serious complication of Pneumonia in children. A number ofstudies are available on demographics, etiology and treatment of empyema but no useful information isavailable on hemodynamic changes occurring in response to acute empyema. Therefore we aimed to evaluatethe serial haemodynamic changes in children with acute empyema and their correlation with severity andout come of the disease.Serial haemodynamic changes were studied prospectively in 25 children with acute empyema before andafter the placement of chest tube and subsequently on day 1, 2, 3 and 10 of hospitalization. Twenty-five ageand sex matched children served as their controls.Their age ranged from 8 months to 12 years (mean 4.2 years). Severity of empyema was graded as mild,moderate and severe in 11, 6 and 8 children respectively. Staphylococcus aureus was the commonestorganism isolated in 11 children. At admission all the children were febrile (mean temp 39.4C) hadtachycardia (mean HR136/mt) and tachypnea (mean RR 62/mt).While CVP was high (10.2? 4cm H2O), thesystolic (102 ? 4mmHg) and mean arterial pressure(77? 3mmHg) was at lower side as compared to theircontrols.The mean changes observed after the chest tube placement were HR- 6/mt; RR - 4.44/ mt; SBP+5mmHg; DBP +2.04mmHg; MAP +3mmHg and CVP-3.1cm H2o (p <.001). Children with severe diseasehad significantly higher CVP (15 ? 3.3cmH2o), low SBP (99 ? 3mmHg) and low serum Sodium (128? 5mEq/L) and Osmolality (278 ? 9 mOsm/L) compared to those with mild or moderate disease. (p<.05 foreach factor).Seven children had features suggestive of syndrome of inappropriate ADH secretion. All thischildren belonged to severe category.It was concluded that hemodynamic compromise is a common occurrence in children with empyema. HighCVP, low SBP, low serum Na+ and Osmolality correlate best with the severity of the disease.Key Words: Empyema, Hemodynamics, Children.

The Comparative Effects of Propofol versus Thiopentone on Left Ventricular Function during Electroconvulsive Therapy

The purpose of this study was to compare the effect of propofol versus thiopentone on haemodynamics during electroconvulsive therapy (ECT), as estimated by echocardiography. Twenty-eight ASA 1 or 2 patients scheduled for ECT were randomly divided into two groups, to receive propofol 1 mg/kg (propofol group, n=14) or thiopentone 2 mg/kg (thiopentone group, n=14). Bilateral ECT was performed after the administration of propofol or thiopentone, succinylcholine and following assisted mask ventilation with 100% oxygen. Cardiac function was examined by transthoracic echocardiography, prior to induction of anaesthesia and throughout ECT until ten minutes after the seizure. In the propofol group, increased end-systolic area (ESA) and decreased fractional area change (FAC) were observed at one minute after the electrical shock compared with the awake condition. In the thiopentone group, increased ESA and decreased FAC were observed from one to three minutes after the electrical shock compared with the awake condition. There was no statistically significant change in after load in the propofol group during the study. In contrast, increased after load was observed from one to three minutes after the electrical shock in the thiopentone group (awake condition, 26±7 mmHg/cm 2 [mean±SD]; one minute after ECT, 42±7*; two minutes after ECT, 44±6*; three minutes after ECT; 40±5*, respectively)(*P<0.05). We concluded that a lesser haemodynamic change occurs after propofol anaesthesia (1 mg/kg) compared with thiopentone anaesthesia (2 mg/kg) during ECT.

Effect of meal induced splanchnic arterial vasodilatation on renal arterial haemodynamics in normal subjects and patients with cirrhosis

Aims—To investigate the relation between changes in splanchnic arterial haemodynamics and renal arterial haemodynamics in controls and patients with cirrhosis.Methods—Superior mesenteric artery pulsatility index (SMA-PI) and renal artery pulsatility index (R-PI) were measured using Doppler ultrasonography in 24 controls and 36 patients with cirrhosis. These measurements were repeated 30 minutes after ingestion of a liquid meal or placebo. Sixteen controls and 24 patients received the meal, and eight controls and 12 patients received placebo.Results—In the fasting condition, patients with cirrhosis had a lower SMA-PI (p<0.01) and a greater R-PI (p<0.01) compared with controls. Placebo ingestion had no effect on splanchnic and renal haemodynamics. In contrast, ingestion of the meal caused a notable reduction in SMA-PI (p<0.01, p<0.01) and an increase in R-PI (p<0.01, p<0.01) in controls and patients with cirrhosis. The meal induced haemodynamic change in SMA-PI was inversely correlated with that in R-PI in controls (t=−0.42, p<0.05) and in patients with cirrhosis (t=−0.29, p<0.05).Conclusions—Results support the hypothesis that renal arterial vasoconstriction seen in patients with cirrhosis is one of the kidney’s homoeostatic responses to underfilling of the splanchnic arterial circulation.