N. Mehta

Usefulness of noninvasive doppler measurement of ascending aortic blood velocity and acceleration in detecting impairment of the left ventricular functional response to exercise three weeks after acute myocardial infarction

Left ventricular (LV) function was assessed by Doppler ultrasound measurement of ascending aortic blood velocity and maximal acceleration in 165 patients 3 to 4 weeks after acute myocardial infarction (AMI); all were undergoing routine 12-lead electrocardiogram exercise stress testing. Patients were grouped according to electrocardiographic stress test response; a positive response was defined as at least 1 mm of ST-segment depression in any lead. The Doppler velocity signal yielded 3 variables of interest: peak velocity, maximal acceleration (an index of inotropic state) and the systolic velocity integral (an index of stroke volume). All 3 Doppler ejection variables were significantly lower at peak exercise in patients with a positive electrocardiographic stress test response than in those with negative response, with maximal acceleration showing the most significance (p less than or equal to 0.001). Coronary angiography was performed in 63 of the 67 patients with positive responses, and patients were separated into 2 groups according to extent of coronary artery disease (CAD): 1- and 2-vessel or 3-vessel CAD. Peak velocity and maximal acceleration were significantly lower in patients with 3-vessel CAD than in those with 1- and 2-vessel CAD (p less than or equal to 0.01 and p less than or equal to 0.01). Discriminant analysis showed maximal acceleration and peak velocity values at peak exercise to be 65% predictive of 3-vessel CAD, onset time to ST-segment depression was 74% predictive and the combination of Doppler and electrocardiographic variables increased 3-vessel CAD predictive value to 80%.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic response to treadmill exercise in normal volunteers: An assessment by Doppler ultrasonic measurement of ascending aortic blood velocity and acceleration

Accurate assessment of ascending aortic blood velocity indices and reproducibility of a Doppler ultrasonic system during exercise were determined; the Doppler technique was then used to assess the effects of age, sex, and beta blockade on exercise hemodynamics. Doppler-determined velocity correlated well with an invasive electromagnetic system. Reproducibility of Doppler variables during three exercise tests was high (coefficient of variation less than 10%) and did not deteriorate appreciably with exercise. Peak velocity (PV) and maximum acceleration (MA) were inversely related to age, the relationship being more significant during exercise, whereas the systolic velocity integral showed no such relationship either at rest or during exercise. Doppler variables showed no difference between sexes, except at high levels of exercise. Beta blockade markedly attenuated the exercise response as shown by significant decreases in both MA and PV during exercise. The Doppler velocity data presented in this study provide a reference against which previously documented changes in exercising ischemic patients can be better related.

Application of the medical anti-shock trouser (MAST) increases cardiac output and tissue perfusion in simulated, mild hypovolaemia

We have studied the haemodynamic effects of the application of the medical anti-shock trouser (MAST) in 10 healthy subjects in the semi-upright position in order to simulate mild hypovolaemia. Left ventricular end diastolic dimension (EDD) was measured by M-mode echocardiography and cardiac output (CO) by the Doppler ultrasound technique. Forearm blood flow (FBF) was measured by plethysmography and blood pressure (BP) by the standard cuff technique. Systematic increases in MAST pressure of up to 80 mm Hg were applied. EDD increased to a maximum of 9.3% (p≤0.01) which was associated with a maximum increase in CO of 31.7% (p≤0.05). FBF increased by a maximum of 54.2% (p≤0.001) whilst BP increased by a maximum of 12% (p≤0.001). These results demonstrate that the application of the MAST is an effective means of transferring blood to the central circulation by compression of the capacitance vessels resulting in significant increases in cardiac output and tissue perfusion. At high pressures there was evidence of compression of resistance vessels, which may be useful in reducing blood loss. The ease and rapidity with which his suit can be applied suggests that it may be useful in the short term treatment of hypovolaemia.

A randomized double-blind trial of an interventional device treatment of functional mitral regurgitation in patients with symptomatic congestive heart failure-Trial design of the REDUCE FMR study

The Carillon Mitral Contour System has been studied in 3 nonrandomized trials in patients with symptomatic congestive heart failure and functional mitral regurgitation. The REDUCE FMR study is a uniquely designed, double-blind trial evaluating the impact of the Carillon device on reducing regurgitant volume, as well as assessing the safety and clinical efficacy of this device. Carillon is a coronary sinus-based indirect annuloplasty device. Eligible patients undergo an invasive venogram to assess coronary sinus vein suitability for the Carillon device. If the venous dimensions are suitable, they are randomized on a 3:1 basis to receive a device or not. Patients and assessors are blinded to the treatment assignment. The primary end point is the difference in regurgitant volume at 1 year between the implanted and nonimplanted groups. Other comparisons include clinical parameters such as heart failure hospitalizations, 6-minute walk test, Kansas City Cardiomyopathy Questionnaire (KCCQ), and other echocardiographic parameters. An exercise echo substudy will also be included.

Risk stratification following myocardial infarction using stress Doppler ultrasound

We assessed left ventricular (LV) function by Doppler ultrasound measurement of ascending aortic blood velocity and maximum acceleration in 165 patients (3–4 weeks after acute myocardial infarction) undergoing routine 12-lead electrocardiogram exercise stress testing, and in an age-matched group of 11 normal subjects. Patients were grouped into those with either positive or negative electrocardiograph stress tests as defined by ≥ 1mm ST segment depression in any lead. The Doppler velocity signal yields a number of variables of interest — the peak velocity, the maximum acceleration (an index of inotropic state), the systolic velocity integral (an index of stroke volume), and mean velocity (an index of cardiac output). All Doppler ejection variables were significantly lower at peak exercise in patients with a positive electrocardiograph stress test when compared to their negative test counterparts, with maximum acceleration showing most significance (p ≥ 0.001). Coronary angiography was performed in 63 of the 67 positive test patients and patients were grouped into those with only 1&2 vessel coronary artery disease and those with 3 vessel disease. Peak velocity and maximum acceleration were significantly lower in the 3 vessel patients than in 1&2 vessel patients (p ≥ 0.01, p ≥ 0.01).

Doppler ultrasound assessment of left ventricular function — Risk stratification in acute myocardial infarction

Velocity ejection variables derived from Doppler ultrasonic interrogation of the ascending aorta were obtained in 92 acute myocardial infarction (AMI) patients and 73 age-matched normal subjects. As a means of stratifying for further risk assessment the AMI patients were divided into clinically defined Forrester subsets, and into survivors and non-survivors of the acute infarction period.

Assessment of Ventricular Function in Man

For the clinician following patients who have suffered myocardial infarction an assessment of ventricular function is an important part of clinical management. What is debatable is how extensively one needs to document the extent of ventricular function in order to manage patients adequately. For example, the widely used New York Heart Association Classification of Heart Failure allows us to at least put patients into Class I or IV very easily, although a lot of debate occurs over who goes into Class II or III. Similarly the use of diuretic drugs and other inotropic agents provide a satisfactory clinical assessment of progress and prognosis. In addition, commonly used indices of cardiac size such as from the bi-plane chest radiograph or echocardiographic dimensions also allow both clinically and prognostically useful information to be obtained. The question that we should ask is, “Would we obtain any more useful information by a more detailed assessment of ventricular function?” This question is important in the light of new more aggressive approaches to the management of patients after myocardial infarction where options might include coronary artery bypass grafting and possibly cardiac transplantation.