Maurizio Santomauro

Endothelial dysfunction in type 2 diabetic patients with normal coronary arteries: A digital reactive hyperemia study

BACKGROUND To assess endothelial function (EF) in type 2 diabetic patients with angiographically normal coronaries compared to diabetic patients with obstructive coronary artery disease (CAD) and to non-diabetic patients, with and without CAD. METHODS One hundred eighty-three patients undergoing coronary angiography were divided in: group 1 with diabetes mellitus (DM) and CAD (n = 58); group 2 with DM without CAD (n = 58); group 3 with CAD without DM (n = 31) and group 4 without CAD and DM (n = 36). EF was assessed by reactive hyperemia index (RHI) using a fingertip peripheral arterial tonometry and compared to values obtained in 20 healthy volunteers. RESULTS RHI was significantly lower in patients with DM compared to patients without DM (1.69 ± 0.38 vs 1.84 ± 0.44; p = 0.019). RHI was comparable among groups 1, 2 and 3, each value being significantly lower compared to group 4 (2 ± 0.44; p<0.001 vs group 1; p<0.005 vs group 2; p<0.002 vs group 3). At multivariate analysis DM and CAD were significant predictors of endothelial dysfunction (ED) (OR = 2.29; p = 0.012; OR = 2.76; p = 0.001, respectively), whereas diabetic patients (n = 116) CAD and glycated haemoglobin (HbA1c) were independent significant predictors of ED (OR = 3.05; p = 0.009; OR = 1.96; p = 0.004, respectively). Diabetic patients with ED (n = 67) had higher levels of HbA1c than diabetic patients with normal endothelial function (7.35 ± 0.97 vs 6.87 ± 0.90; p = 0.008) and RHI inversely correlated to HbA1c (p = 0.02; r = -0.210). CONCLUSIONS Diabetic patients with and without CAD show significantly impaired peripheral vascular function compared to non-diabetic patients without CAD. ED in diabetic patients without CAD is comparable to that of patients with CAD but without DM. HbA1c is a weak independent predictor of ED.

Evaluation, by Noninvasive Methods, of the Effects of Acute Loss of Thyroid Hormones on the Heart

To evaluate the effects of the acute loss of thyroid hormones on the heart the authors studied 11 women with acute hypothyroidism. The cardiac study was performed by means of electrocardiography (ECG), radionuclide ventriculog raphy (RNV) at rest and under effort, and monodimensional echocardiography (MD-echo) and was repeated with ECG and MD-echo after six months of thyrox ine suppressive therapy. The ECG showed a significant prolongation of QT in terval and flattening and inversion of T wave with normal heart rate. The MD-echo revealed left ventricular function in the normal range and normal left ventricular dimensions. RNV showed the ejection fraction in the lower normal range at rest, which increased to a smaller extent under effort in comparison with a control group. The ECG performed during suppressive therapy with L- thyroxine yielded normal findings with an increase of heart rate and of R wave amplitude, and the MD-echo showed no significant variations of cardiac func tion due to the increase of heart rate.

Efficacy of Ticlopidine in the Prevention of Thromboembolic Events in Patients with VVI Pacemakers

This study was designed to evaluate whether long‐term treatment with ticlopidine reduces the incidence of thromboembolie episodes in patients with a VVI pacemaker. One hundred eJeven patients with a VVI pacemaker were randomly assigned to two groups: group A (52 patients) was treated with ticlopidine at the dose of 250 mg a day; and group B (59 patients) was not treated and served as a control group. The primary analysis of efficacy of ticlopidine was based on the occurrence of thromboemboJic episodes and of cardiovascular and cerebrovascular deaths. The mean follow‐up period was 66 months. In group A, there was a significant reduction in the incidence of thromboembolic episodes (P < 0.05) with a smaller incidence of total cardiovascular and cerebrovascular deaths (8 in group A and 18 in group B; P = 0.05) as compared with group B. Twelve percent of patients had moderate side effects with 1 dropout (epistaxis). Our data confirm the high incidence of thromboembolic events in patients with a VVI pacemaker and demonstrate the efficacy of ticlopidine in preventing them.

Pacemaker Malfunction Due to Subcutaneous Emphysema — A Case Report

The authors describe a case of pacemaker malfunction due to a critical in crease of impedance resulting from air entrapment in the pacemaker pocket.

Comparison between exercise and trans-oesophageal atrial pacing in patients with coronary artery disease: technetium-99m methoxy isobutyl isonitrile simultaneous evaluation of ventricular function and myocardial perfusion

In this study we compared the results of exercise and trans-oesophageal atrial pacing (TAP) technetium-99m methoxyisobutyl isonitrile (99mTc-SESTAMIBI) cardiac imaging in the evaluation of left ventricular (LV) function and myocardial perfusion in patients with angiographically proven coronary artery disease. Ten patients (8 men and 2 women, mean age 59 ± 6 years) were submitted to 3 separate injections of 99mTc-SESTAMIBI, one under control conditions, one after exercise and one after TAP. LV ejection fraction, as measured by electrocardiogram (ECG) gated first pass, decreased from 49 ± 5 % under control conditions to 42 ±6% during exercise (P < 0.05 versus control) and to 43 ±8 % during TAP (P<0.05 versus control and insignificant change versus exercise). Segmental myocardial perfusion analysis was performed on a total of 150 myocardial segments. On both exercise and TAP 99mTc-SESTAMIBI studies, 103 segments (69% of the total) were normal, 32 (21 %) had reversible, and 15 (10%) irreversible, perfusion defects. Relative regional tracer uptake was not statistically different between exercise and TAP in normal regions (91.1 ± 9.1 % versus 90.7 ± 8.5 %, respectively), in regions with reversible (61.9±12% versus 62.4±10.4%, respectively) and irreversible perfusion defects (55.8 ± 7.8 % versus 58.8 ± 9.5 %, respectively). Our results demonstrated that 99mTc-SESTAMIBI TAP cardiac imaging shows similar results to 99mTc-SESTAMIBI exercise myocardial scintigraphy in the assessment of LV function and myocardial perfusion in patients with coronary artery disease.

Fourier Analysis in Patients with Different Pacing Modes

The purpose of this study was to evaluate the usefulness of phase analysis in detecting the altered activation sequence induced by different pacing modes. Radionulide ventriculography and planar gated blood pool scintigraphy were performed at rest in 56 patients with different pacemakers. This method permitted us to localize the pacemaker impulse site in the right ventricie and its diffusion in the heart. In patients with VVI pacemaker, this technique showed an evident asynchronism of contraction and relaxation of each ventricle and the standard deviation of phase angle (σ), calculated by computer, is greater during pacing than sinus rhythm for left (LV) and right (RV) ventricles (LV σ: 17°± 4 vs 11°± 3, < 0.001; RV σ: 31°± 7 vs 14°± 4, P < 0.001). In the patients with VVI rate responsive pacemakers, the LV σ changed from 18.5 ± 3 under pacing to 11°± 3 in sinus rhythm, P < 0.001, while the RV σ changed from 30°± 8 to 14°± 4, P < 0.001. Instead in the patients with DDD pacemakers, the LV σ changed from 15.5°± 2 under pacing to 11°± 3 in sinus rhythm, P < 0.05, while the RV cr changed from 29.1°± 6 to 14°± 4, P < 0.001. Besides in patients with VDD pacemakers, the LV σ changed from 14.9°± 3 during pacing to 11°± 3 in sinus rhythm, P < 0.01, and from 27.5°± 5 to 14°± 4 for the right ventricle, P < 0.01. So the technique of Fourier analysis permits us to examine the effects of a temporal inhomogeneity induced by different pacing modes, and it can be utilized to assess the optimal atrioventricular delay in DDD paced patients.

Platelet Aggregability in Patients with a VVI Pacemaker

Several studies have suggested an increased incidence of thromboembolic events in patients with VVI pacemaker (VVI patients); furthermore, other authors have demonstrated that a treatment with anticoagulants or antiplatelet drugs may be effective in reducing thromboembolic events, thus suggesting an increased formation of platelet thrombi in these patients. In this respect, platelet aggregability was investigated in ten VVI patients and ten age– and sex–matched subjects. β–thromboglobulin (β–Tg) and platelet factor 4 (PF4) plasma levels were determined as weJJ as platelet aggregation induced by ADP, collagen, epinephrine, and arachidonic acid. Plasma β–Tg JeveJs were increased in the patient group (86 ± 24 vs 24 ± 13 ng/mL; P < 0.001) in presence of normal PF4 values (14 ± 11 vs 13 ± 6 ng/mL; NS). Aggregation curves showed abnormal values of maximal amplitude, slope, and lag time. In particular, maximal amplitude was significantJy higher in VVI patients as compared with controls (ADP P < 0.01, collagen P < 0.001, adrenaline P < 0.01, arachidonic acid P < 0.05). These findings strongly suggest an increase of platelet activity in VVI patients.

Haemodynamic effects of dual-chamber pacing versus ventricular pacing during a walk test in patients with depressed or normal left ventricular function.

PurposeDual-chamber rate-modulated pacing provides haemodynamic benefits compared with ventricular pacing at rest, but it is unclear whether this also holds true during physical exercise in patients with heart failure. This study assessed the haemodynamic response to a walk test during dual-chamber pacing and ventricular pacing in patients with depressed or normal left ventricular (LV) function.MethodsTwelve patients with an LV ejection fraction <50% and 11 patients with an LV ejection fraction ≥50% underwent two randomised 6-min walk tests under dual-chamber rate-modulated pacing and ventricular pacing at a fixed rate of 70 beats/min. All patients had a dual-chamber pacemaker implanted for complete heart block. LV function was monitored by a radionuclide ambulatory system.ResultsIn patients with depressed LV function, the change from dual-chamber pacing to ventricular pacing induced a decrease in end-systolic volume at the peak of the walk test (P<0.05), with no difference in end-diastolic volume. As a consequence, higher increases in LV ejection fraction (P<0.0001) and stroke volume (P<0.01) were observed during ventricular pacing. No difference in cardiac output was found between the two pacing modes. In patients with normal LV function, the change from dual-chamber pacing to ventricular pacing induced a significant decrease in cardiac output (P<0.005 at rest and P<0.05 at the peak of the walk test).ConclusionCompared with dual-chamber rate-modulated pacing, ventricular pacing improves cardiac function and does not affect cardiac output during physical activity in patients with depressed LV function, whereas it impairs cardiac output in those with normal function.

Follow-Up of a Respiratory Rate Modulated Pacemaker

The efficacy of 27 respiration sensitive rate modulated pacemakers (Biorate RDP‐3, Biotec) implanted in the left pectoral area was evaluated every 3 months during a mean follow‐up period of 29 months (range 10‐50 months]. Rate modulation function was unchanged other than for three patients in whom the auxiliary leads became displaced. Two implants lost ventricular sensing in this nonprogrammable model. In all but the three patients, Holter monitoring demonstrated pacing rate variation corresponding to daily activity. Stress test duration increased from 8.2 ± 1.5 minutes (in fixed rate WI rate) to 12.83 ± 2.0 minutes (in the VVIR mode) (P < 0.05). Right arm movement increased the pacing rate by 5 ± 3 beats/min (NS), while the left arm movement increase was 30 ± 5 beats/min (P < 0.05). Mental, arithmetic, and nifedipine tests did not change the rate modulated pacing rate. The system responded to a change in respiratory rate by an increase in stimulation rate. A satisfactory response in sensitivity and velocity was present only with medium‐high workloads. Interference with rate modulation occurred with movement of the arm ipsillateral to the implanted pulse generator.

Different Automatic Mode Switching in DDDR Pacemakers

Mode-switching algorithms are designed to alleviate symptoms related to tracking of atrial arrhythmias, that may result in inappropriately rapid or irregular ventricular pacing[1–19]. The ideal mode-switching algorithm should discriminate sinus tachycardia, a rhythm that should be tracked, from pathological atrial arrhythmias, rhythms that generally should not be tracked. In order to minimize symptoms related to the occurrence of atrial arrhythmias, the mode-switching algorithm should change quickly from a tracking to a non-tracking mode at the onset of the pathological atrial rhythm and remains in this mode until the arrhythmia terminates. Once sinus rhythm has been restored, the pacemaker should revert quickly to the normal atrial tracking mode. There are several potential causes of symptoms that relate to mode switching. First, an irregular paced ventricular intervals at the onset of an atrial arrhythmia before conversion to a non-tracking mode. Second, failure of the device to convert to a non-tracking mode because of intermittent undersensing of the atrial electrocardiogram may result in continued irregular or rapid ventricular pacing [20]. Third, inappropriate reversion to a tracking mode despite persistence of an atrial arrhythmia may also be caused by intermittent undersensing of the atrial electrocardiogram. Fourth, an overly sensitive mode-switching algorithm may result in loss of atrio-ventricular (AV) synchrony in sinus rhythm [2,11,17,19]. Finally, intrinsic AV conduction of an atrial arrhythmia may produce symptoms that are unrelated to the pacemaker [21]. Although all manufacturers of dual chamber pacemakers offer devices that provide mechanisms for managing the occurrence of atrial arrhythmias, the mode-switching algorithms that are available differ significantly in their sensitivity, specificity, and speed of mode conversion at the onset and termination of atrial arrhythmias. There are potential compromises between sensitivity and specificity with these algorithms, the balance of which may determine the frequency of arrhythmia-related symptoms. Atrial-based pacing is associated with a risk of developing atrial fibrillation lower than ventricular-based pacing for patients with sinus node dysfunction [22-25].