Preoperative intra aortic balloon pump support in high risk coronary artery bypass patients

Evaluation of the effect of preoperative Intra-Aortic Balloon Pump [IABP] support in high risk patients undergoing coronary artery bypass grafting [CABG]. Between February 1999 and February 2004, forty one high risk patients undergoing coronary artery bypass graft surgery [CABG], presenting with two or more of these criteria: Left ventricular ejection fraction [LVEF /= 60%, recent myocardial infarction <6 weeks, left ventricular hypertrophy and unstable angina were divided into 2 groups: Group [1] [N=28 patients] recevied preoperative IABP support prior to initiation of cardio-pulmonary bypass [CPB] and Group [2] [N=13 patients] did not recevie preoperative IABP support. Ninety% of patients had LEF<40%, 20% had left main stem stenosis, 15% had unstable angina and 15% had recent MI. The CPB-time was shorter in group [1] with P < 0.02, while CC time showed no difference. Postoperative low cardiac output was less in group [1] with P < 0.001. The IABP was removed after 31.3 +/- 0.5 hours with no complications. Ventilation time was shorter in group [1] with P < 0.0001. Surgical Intensive Care [SICU] stay was shorter in group [1] with P < 0.04 and the hospital stay was shorter as well with P < 0.005. Cardiac index increased significantly in group [1] patients 5 minutes, 4, 12 and 24 hours post bypass with P < 0.04, P < 0.05, P < 0.001, and P < 0.0001 respectively. Group [1] patients had a better improvement of cardiac performance than group [2]. No mortality was found in group [1], but group [2] patients showed mortality of 7.7%. Three months follow up of patients showed no group differences in LVEF%. The use of preoperative IABP in high risk patients improves cardiac performance, shortens the SICU stay as well as hospital stay

Blood cardioplegia: haemodynamic, electrocardiographic and enzymatic assessment experience of Dubai Hospital

The technique of blood cardioplegia with cold induction, cold maintenance and warm reperfusion was assessed using haemodynamic, electrocardiographic and enzymatic parameters in one hundred seventy [170] consecutive patients who underwent coronary artery bypass grafting. The mean age was 49.6 +/- 0.5 years. Eleven percent of the patients had unstable angina, and 10% of the patients had ejection fraction less than 30%. The mean number of grafts was 3.4 +/- 0.06. Combined antegrade/retrograde cardioplegia was given in 83% of patients. After aortic declamping 94% of patients had spontaneous recovery to sinus rhythm. Inotropic support was needed in 12% of patients, while 7.6% required Intra Aortic Balloon Pump support. As regards electrocardiographic changes, 10% of patients had new ischaemic changes on the day of surgery, which was persistent in 8% of patients up to the third postoperative day. For creatine kinase-MB isoenzyme, 15% of patients had considerable myocardial damage [levels> 100 U/L], which dropped to near normal levels by the third postoperative day. The postoperative mortality rate was 2.3%. This study suggests that blood cardioplegia may offer a good method of myocardial protection during coronary artery bypass grafting

Corrected ejection fraction: a new index showing less dependency on preload and afterload changes

In the attempt to find a useful measurement of myocardial contractility with minimal dependence on loading changes, equation was developed: Corrected ejection fraction [EFc] = [EF + [MSV x ASV] /EDV] /2 where, EF = conventional ejection fraction, MSV = mitral stroke volume, ASV = aortic stroke volume, EDV = end-diastolic volume. We studied 15 normal subjects [13 males], measuring EF by 3 different methods: Simpson's biplane using 2-D echo, cube method using M-mode echo; and Quinones method using M-mode echo. ASV and MSV were measured using Doppler echocardiography. EF and EFc were measured at rest and during 4 maneuvers that alter loading condition: Valsalva maneuver, isometric hand grip, passive leg elevation and standing. The frequency [%] each index varied by no more than +/- 10% between rest and interventions were compared. Using Simpson's biplane method, EFc was relatively unaffected by maneuvers in 88% of readings versus 45% for EF, and the difference was statistically significant [P< 0.01]. Using cube method, EFc was relatively unaffected by maneuvers in 98% of readings versus 38% for EF, and the difference was statistically significant [P<0.01]. Using Quinones method, EFc was relatively unaffaced by maneuvers in 87% of readings versus 35% for EF, and the difference was statistically significant [P< 0.01]. In addition, EF had an inverse relationship with flow EF i.e [AS, x MSV] /EDV]. Thus, EFc as a measure of myocardial contractility appears to be less dependent than conventional EF on loading states. Therefore, EFc may be a useful index for evaluating left ventricular function in patients with altered loading states including valvular regurgitation

Noninvasive estimation of left ventricular end diastolic pressure from ejection fraction and mean arterial blood pressure

Non-invasive estimation of left ventricular end-diastolic pressure [LVEDP] has important clinical applications. Previous studies showed that LV systolic function is an important determinant of LV diastolic filling. However, non-invasive estimation of LVEDP using ejection fraction [EF] has not been tried. The aim of this study was to find out a reliable method for estimating LVEDP non-invasively by means of EF, including validation of the first data set. We tested the relationship: LVEDP = mean arterial blood pressure [MABP] x [I-EF]. All measurements were taken using cardiac catheterization and left ventriculography, in 41 patients with coronary artery disease. Patients were divided into 2 groups according to the values of EF: Group A [23 patients, ages 58 +/- 12 years] with EF> 0.75, and group B [18 patients, ages 59 +/- 10 years] with EF < 0.75. Estimated and measured LVEDP were tested using linear regression and correlation, the results were: group A [r =0.758, P< 0.001], group B [r = 0.673, P < 0.01]. For 10 additional patients [validation group, ages 57 +/- 11 years] estimated LVEDP was calculated using formula from the first date set, estimated LVEDP = 0.54 [MABP x [I-EF]] 2.23. In the validation group, EF was measured using echocardiography within 24 hours of cardiac catheterization, and MABP was measured using sphygmomanometer just before cardiac catheterization. The estimated LVEDP showed a highly significant correlation with the invasively measured LVEDP [r =0.831, P<0.01] in addition, both had good agreement with each other [limits of agreement between -4 and 3 mmHg]. Thus, LVFDP can be estimated noninvasively from EFand MABP with an acceptable accuracy

Silent myocardial ischemia: left ventricular function and hemodynamic abnormalities

30 patients with documented coronary artery disease were subjected to Echo-Doppler assessment of left ventricular function during and after periods of silent myocardial ischemia [SMI]. Diagnosis of SMI was based on the presence of asymptomatic wall motion abnormalities [WMA] that improve after sublingual nitroglycerine. During SMI, systolic, diastolic and mean blood pressure as well as rate pressure product and WMA score index were significantly increased. Ejection fraction [EF], stroke volume, systolic blood pressure to end systolic volume ratio, peak. E velocity, E/A ratio, peak filling rate normalized to mitral stroke volume, duration and time velocity integral [TVI] of early filling and TVI[E/A] were significantly decreased, while peak-A velocity, TVI[A] and fraction of late filling [%TVI[A]] were significantly increased. E-wave acceleration, slope and time to onset and the heart rate did not show significant changes. The change [control period value-silent ischaemia value] in WMA score index showed significant inverse correlation with the change in EF, E/A and TVI[E/A] and direct correlation with%TVI[A]. SMI has an adverse effect on hemodynamics, LV systolic and diastolic functions and its alleviation results in reversal of this effect