Pierre Block

Contrast enhanced and functional magnetic resonance imaging for the detection of viable myocardium after infarction

PURPOSE Viable myocardium after acute myocardial infarction may be characterized by magnetic resonance imaging (MRI) either by demonstration of recovery of wall motion under dobutamine stress or by perfusion patterns after contrast medium administration. This study examines the relation between the two techniques. MATERIALS AND METHODS Gradient-echo MRI at rest and under low-dose dobutamine stress was performed in 28 patients within the first 2 weeks after acute myocardial infarction. In addition, spin-echo MRI was performed after gadolinium-DOTA administration. Wall motion at rest and under stress was scored to assess the contractile reserve of the infarct regions. Infarct enhancement patterns were classified as subendocardial, transmural, or as a doughnut pattern. RESULT Subendocardial or absent infarct enhancement was related to functional recovery under stress in 31 of 37 infarct segments. Transmural infarct enhancement was correlated with the absence of functional recovery in 10 of 17 infarct segments (p < 0.002), indicating nonviability. The doughnut pattern was exclusively associated with the absence of viability (five of five). CONCLUSION Contrast enhancement patterns are related to residual myocardial viability.

Sublingual nitrates during head-up tilt testing for the diagnosis of vasovagal syncope.

Pharmacologic stimulation during head-up tilt test (HUT) is used to increase the diagnostic yield of the test to detect vasovagal syncope. Reported lack of specificity of stimulation with intravenous isoproterenol has made a pharmacologic alternative desirable. Because nitrates are known to cause syncope of a vasovagal origin, we administered sublingual nitrates after classic tilt test in 32 patients with a history of typical vasovagal syncope and 20 healthy volunteers to assess the sensitivity, specificity, and accuracy of this new HUT technique. During the classic HUT four (13%) patients had syncope; after administration of sublingual nitrates, this number increased to 28 (87%). In the control group no subject had syncope during classic HUT, whereas during nitrate administration six (30%) had syncope. Sublingual nitrate stimulated HUT revealed a maximum accuracy of 83% at a cutoff point of 11 minutes, giving a sensitivity of 81% and specificity of 85%. Sublingual nitrate administration increased the accuracy of HUT in diagnosing vasovagal syncope in patients with a history of typical vasovagal syncope.

Identification of best electrocardiographic leads for diagnosing anterior and inferior myocardial infarction by statistical analysis of body surface potential maps

In view of the increasing interest in quantifying and modifying the size of myocardial infarction (MI), it is important to look for clinically practical subsets of electrocardiographic leads that allow the earliest and most accurate diagnosis of the presence and electrocardiographic type of MI. A practical approach is described, taking advantage of the increased information content of body surface potential maps over standard electrocardiographic techniques for facilitating clinical use of body surface potential maps for such a purpose. Multivariate analysis was performed on 120-lead electrocardiographic data, simultaneously recorded in 236 normal subjects, 114 patients with anterior MI and 144 patients with inferior MI, using as features instantaneous voltages on time-normalized QRS and ST-T waveforms. Leads and features for optimal separation of normal subjects from, respectively, anterior MI and inferior MI patients were selected. Features measured on leads originating from the upper left precordial area, lower midthoracic region and the back correctly identified 97% of anterior MI patients, with a specificity of 95%; in patients with inferior MI, features obtained from leads located in the lower left back, left leg, right subclavicular area, upper dorsal region and lower right chest correctly classified 94% of the group, with specificity kept at 95%. Most features were measured in early and mid-QRS, although very potent discriminators were found in the late portion of the T wave.(ABSTRACT TRUNCATED AT 250 WORDS)

Toward the optimal lead system and optimal criteria for exercise electrocardiography

To define the optimal lead system for exercise electrocardiography, data of the whole body surface potential distribution were analyzed in 25 normal subjects and in 25 patients with coronary artery disease at rest and during exercise. All patients had a normal electrocardiogram at rest. The sensitivity of the standard chest leads was 60 percent; it improved to 84 percent with the body surface map whereas both methods had a 100 percent specificity. On the basis of these data, and reports from other centers, it is concluded that a single bipolar lead from the right subclavian area to lead V5 is adequate in those laboratories that are restricted to testing subjects with a normal electrocardiogram at rest. In patients with a previous infarction or other abnormalities in the electrocardiogram at rest three (pseudo) orthogonal leads or several standard leads are necessary. Recommendations for optimal measurements from the exercise electrocardiogram are based on quantitative computer analysis of the selected leads in larger groups of patients. Best results were obtained with a combination of S-T amplitude, S-T slope and heart rate. The improvement in sensitivity from 50 percent with visual analysis to 85 percent with computer was similar to that obtained with body surface mapping. Changes of the P wave and QRS complex during exercise appeared to be of little diagnostic value. The pathophysiologic mechanisms that contribute to the changes of the electrocardiogram during exercise are discussed.

Patient Compliance and Therapeutic Coverage - Amlodipine Versus Nifedipine (slow-release) in the Treatment of Angina-pectoris

Patient compliance with therapy is often poor and overestimated by the treating physician; it is particularly important in cardiovascular diseases such as hypertension and angina pectoris. Compliance was studied in an open parallel study in out-patients with stable angina pectoris, given either amlodipine (5 mg, once daily) or slow-release nifedipine (20 mg, twice daily) for 12 weeks. Compliance was assessed using pill counting and using an electronic device, the medication event monitoring system, to record the time and date of each opening and closure of the pill container. There was no difference between the two groups in pill count or taking ‘in compliance’ (the percentage of prescribed doses taken as indicated by the monitoring system). Compliance was significantly better (P < 0.001) with amlodipine, however, for ‘correct dosing’ (the percentage of days on which the correct dose was taken) and for ‘timing compliance’ (the percentage of doses taken at the prescribed time interval after the last dose). ‘Therapeutic coverage’ (the estimated proportion of treatment time for which the drug was active) was also significantly better for amlodipine (P < 0.001). There was no difference in reported side-effects between the two therapies.

Regional distribution of 123I-(ortho-iodophenyl)-pentadecanoic acid and 99Tcm-MIBI in relation to wall motion after thrombolysis for acute myocardial infarction

To characterize the myocardium after thrombolytic therapy for infarction single photon emission computed tomographic (SPECT) studies with 123I-(ortho-iodophenyl)-pentadecanoic acid (oPPA) and 99Tcm-methoxyisobutyl isonitrile (MIBI) were obtained at rest in nine patients within a fortnight after the acute event. A decreased oPPA activity compared to MIBI was observed in 15/45 segments (7/9 patients). The segments with discordant oPPA/MIBI activities showed less severe wall motion abnormalities than the segments with concordant decreased oPPA and MIBI activities (P=0.004). A significant association was found between discordant oPPA/MIBI activities and the early evolution of wall motion following thrombolysis: discordant oPPA/MIBI activities were present in nine of the 11 segments (82%) with improved wall motion, while the wall motion of the seven segments with similar decreased oPPA and MIBI activities was unchanged or had deteriorated (P=0.018). It is concluded that metabolic abnormalities often persist longer than perfusion and wall motion abnormalities soon after thrombolysis, and that 123I-oPPA in combination with 99Tcm-MIBI is useful to demonstrate myocardial areas which have been salvaged by thrombolysis.

Primary prevention of coronary heart disease in general practice: a cross sectional population study: Primary Prevention of Coronary Heart Disease

The aim of this study was to assess the interventions by general practitioners on cardiovascular risk factors among persons without a history of cardiovascular disease attending for a cardiovascular check‐up. All inhabitants of three Belgian towns aged between 45 and 64 years were invited for a cardiovascular check‐up and blood test. Of all the attending persons without a history of cardiovascular disease (n = 898), 51% received at least one prescription, diet or health advice: 28% for hyperlipidaemia, 23% for physical activity, 22% for caloric intake, 9% for blood sugar, 5% for blood pressure and 4% for smoking. Interventions on lipoproteins, blood sugar and smoking habits were significantly more often proposed to persons with a medium or high cardiovascular risk compared to those at low cardiovascular risk. For persons at low cardiovascular risk, therapeutic lifestyle changes are often not advised, and isolated risk factors often remain untreated.

Magnetic resonance imaging of the heart in a case of hepatocellular carcinoma extending into the right atrium

Hepatocellular carcinoma is the most common primary malignant liver tumor occuring in more than 1 million cases a year all over the world. Vascular invasion is known to occur in 30% of patients at initial presentation [1]. An extension of the tumor into the right atrium is well described in the literature [2], with surgical resection as the only procedure available. But the diagnosis is often difficult before death. We report a case in which magnetic resonance imaging of liver and heart shows the extension of this tumor into the right atrium

Aorta dissection with two separate false lumina, diagnosed by magnetic resonance imaging—A case report

A forty-five-year—old woman with a history of arterial hypertension was diagnosed as having a dissection of the ascending aorta progressing toward the descending aorta, where two false lumina were shown on magnetic resonance dynamic and spin-echo imaging and confirmed at autopsy. The other imaging techniques used did not allow a precise visualization of this anomaly. The place of the different imaging techniques in this type of aortic dissection is discussed.

Body Surface Mapping: Contribution and Limits for the Diagnosis of Right Ventricular Myocardial Infarction in Patients with Posterior, Inferior or Deep Septal Left Ventricular Myocardial Infarction

In this paper we report our experience with the body surface potential mapping techniques for the diagnosis of right ventricular myocardial infarction (RVMI) in patients with acute posterior, inferior or deep septal myocardial infarction (PIDSMI). In particular we looked wether this technique would be more performant than the conventional and easier to assess E.C.G. criteria such as proposed by Candell Riera (↗ST in V4R). The radionuclide ventriculography was taken as reference.