Malignant ventricular arrhythmias induction by programmed electrical stimulation of the right ventricular outflow tract only during type 1 Brugada ECG maximization

OBJECTIVE

The role of electrophysiology study in Brugada syndrome (BS) sudden cardiac death risk stratification remains controversial and seems to depend on the phenotypic expression of the channelopathy. Ajmaline has a key role in the diagnosis of BS. We observed that programmed electrical stimulation (PES) of the right ventricular outflow tract (RVOT), only when type 1 BS ECG is unmasked by ajmaline administration, induces ventricular arrhythmias.

CASE REPORT

We describe a case of ventricular fibrillation induction by PES of the RVOT when type 1 BS ECG is revealed by ajmaline, in a patient with a baseline dynamic intermittent type 1 and 2 BS ECG.

CONCLUSIONS

The heterogeneous clinical presentations of BS are due to the underlying mechanisms. PES of the RVOT during positive ajmaline test maximizes the channelopathy and therefore sudden cardiac death risk-stratification in BS.

Ventricular fibrillation induction and diffuse abnormal ST-segment response to ajmaline in a patient with apparent pre-existing dynamic right bundle branch block

OBJECTIVE

ST-segment elevation in the right precordial electrocardiography (ECG) leads in Brugada syndrome (BS) can be unmasked by class I anti-arrhythmic drugs (sodium channel blockers) administration. It is still debated whether this ECG pattern is better explained by abnormal repolarization or ventricular conduction and depolarization. Conduction diseases can conceal type 1 BS-like ECG in standard V1-V3 leads. ECG alterations were found also in alternative leads. The role of electrophysiology study (EPS) in sudden cardiac death risk stratification remains controversial, and could depend on the phenotypic expression of the cardiac sodium channels disease.

CASE REPORT

We describe unmasked diffuse J-point and ST-segment anomalies in peripheral and precordial ECG leads and ventricular fibrillation (VF) induction by EPS after ajmaline administration in a patient with pre-existing atypical right bundle branch block (RBBB) concealing subtle anomalies in standard V1-V3 leads. RBBB was influenced by the underlying BS-like ECG associating repolarization anomaly and pre-existing conduction disease. EPS induced VF when RBBB was associated with BS-like ECG, and failed to induce VF when RBBB was present alone.

CONCLUSIONS

BS phenotype heterogeneity requires further studies to improve the knowledge of its pathophysiological mechanisms associated with conduction diseases in order to better identify an individual therapy and prognostic stratification.

Prevention of acute renal failure post-contrast imaging in cardiology: a randomized study

BACKGROUND

The contrast-induced nephropathy (CIN) is the third most common cause of acute renal failure (ARF) and the worsening in a pre-existing chronic renal failure (CRF), with a foreseeable increase of morbidity, mortality, length of the stay in hospital and, as a consequence, of the health costs. We studied the effectiveness of N-acetylcysteine (NAC) associated with sodium bicarbonate (Na2HCO3) infusion in order to prevent CIN in patients undergoing coronary angiography with administration of contrast medium.

MATERIALS AND METHODS

296 patients with indication to perform coronary angiography were included in a randomized, observational study. All patients were randomly assigned to receive pre- and post-contrast hydration with 1500 ml of 0.9% saline solution infusion (Group A) or NAC (1200 mg × 2 days) + Na2HCO3 (Group B). The primary end-point was to examine CIN appearance, defined as a raise in serum values of Cr (Creatinine) ≥ 0.5 mg/dl or ≥ 25% within 24-72 hours after the exposure to the contrast medium.

RESULTS

It has been observed a frequency of CIN of 9.4% in Gr. A compared to 7.2% in Gr. B. Nevertheless, when we put these results through a more accurate screening according to gender, degree of raise in creatinine levels and the extent of change in GFR (glomerular filtration rate), we observed a very different behaviour. In patients with normal Cr and CrCl (Clearance of Creatinine) the frequency of CIN was similar in both group A and B (approximately 5%). In patients with normal Cr but reduced ClCr the use of NAC was more effective than hydration in preventing CIN (0% vs 18% in prevalence respectively in B and A group). In patients with moderately reduced Cr and CrCl, hydration with saline solution was more effective than NAC + Na2HCO3 (8.6% vs 17.6%) while in patients with severe CRF the combined use of NAC + Na2HCO3 showed off to be very successful in preventing CIN compared to the merely hydration (0% vs 50%).

CONCLUSIONS

In patients affected by severe CRF who are undergoing investigations with contrast medium administration, such as coronary angiography, the combined use of NAC + Na2HCO3 infusion significantly reduces the risk of developing CIN. In other circumstances the final result is related to the degree of previous GFR or creatinine values alteration or to gender. In such situations the combined use of both substances is more questionable and sometimes ineffective.

Functional changes cardiovascular: normobaric activity and microgravity in young healthy human subjects

BACKGROUND

The cardiovascular system works to maintain homeostasis through a series of adaptive responses to physiological requirements. Different self-regulatory mechanism prevent the effects induced by hydrostatic pressure changes on oncotic pressure caused by postural changes. Gravity exerts a strong influence on the postural changes with implications on the cardiovascular system. In orbit, gravity (+Gz) is responsible of mass redistribution of circulating blood flow. The aim of this study was the evaluation of the adaptive responses of cardiovascular system to postural changes with and without the use of the Lower Body Negative Pressure (LBNP). We considered that pressure changes that occur in human body in orbit can be simulated experimentally with use of Tilt-Test (Clino/ortho; Clino/head-down; head-down/ortho). This investigation could be useful for studying the influence on astronauts of long flights.

SUBJECTS AND METHODS

We studied in 12 months, 30 young healthy volunteers (20 males, 10 female) during postural change tests. In the first evaluation they were submitted to tilt-test for 40 minutes, remaining in head-up +60 degrees (this state corresponds to a kind of gravitational stress +Gz) and in head-down to -30 degrees (-Gz) for 20 minutes. During the second assessment (after 5 +/- 1 days) all volunteers wear a device that simulate a state of LBNP at -20 mmHg. Afterwards, they were processed to 20 minutes in Head Down -8 degrees and after 2 hours of rest to 20 minutes at -15 degrees. Volunteers were monitored measuring blood pressure, heart rate and by Transthoracic Echocardiogram (TTE).

RESULTS

Collected data were elaborated by a statistical analysis. We observed during orthostatic position for 40 min (+60 degrees) without LBNP, lower diameters and volumes of left and right ventricular (p < 0.05) and an increase in heart rate in comparison with the baseline conditions in clinostatism. Despite the reduction of preload volume, the mean value of cardiac output does not vary significantly. In Trendelemburg (-15 degrees) data show a non-significant variation (p > 0.05) of left and right ventricular diameters and volumes, while cardiac output and systolic blood pressure varies significantly (p < 0.05) compared to clinostatic and orthostatic position. With LBNP in head down to -8 degrees and -15 degrees, systolic and diastolic arterial pressure, ventricular volumes and cardiac output were unchanged if compared to values obtained in clinostatism with and without LBNP. If compared to -30 degrees in Trendelemburg without LBNP, data reached statistical significance (p < 0.05).

CONCLUSIONS

The cardiovascular system and the autonomic nervous system, respond to postural changes and to volemia alterations, maintaining the physiological cardiac output, in order to preserve the metabolic requirements of body.

Catheter ablation of atrial tachycardia after interatrial defect repair with patch apposition

A 54-year-old woman with history of septal atrial mixoma surgically treated and drug-refractory supraventricular tachyarrhythmia underwent catheter ablation of macro-reentry areas near the pericardial patch placed to repair an interatrial defect. The use of ablative therapy has been successful to cure this arrhythmia.

Cardiac resynchronization therapy: could a numerical simulator be a useful tool in order to predict the response of the biventricular pacemaker synchronization?

BACKGROUND AND OBJECTIVES

Cardiac resynchronization therapy (CRT) can be considered as an established therapy for patients with moderate or severe heart failure (HF), depressed systolic function and a wide QRS complex. Biventricular stimulation through the CRT is applied at patients with an intra and/or inter-ventricular conduction delay. The goal of this technique is to resynchronize contraction between and within ventricles. A numerical model of the cardiovascular system, together with the numerical model of the biventricular pacemaker (BPM), can be an useful tool to study the better synchronization of the BPM in order to reduce the inter-ventricular and/or intra-ventricular conduction delay.

SUBJECTS AND METHODS

Within a group of patients which were representative of the most common disease etiologies of heart failure, seven patients, affected by dilated cardiomyopathy undergoing CRT with BPM, were studied and simulated using the numerical model of the cardiovascular system CARDIOSIM. The patients were submitted to echocardiographic evaluation (with pulsate Doppler and tissue Doppler imaging) and electrocardiography evaluation in order to evaluate intra-ventricular and/or inter-ventricular dyssynchrony. These evaluations were made three times: the first one before BPM implantation, the second and the third one respectively within seven days and six months after BPM implantation. Also haemodynamic parameters were measured. Using the software simulator, the pathological conditions before CRT, within seven days and within six months since CRT were reproduced for each patients in order to evaluate the following haemodynamic parameters: the end-systolic and end-diastolic left ventricular volume, the systolic pulmonary arterial pressure, the systolic, diastolic and mean aortic blood pressure and the ejection fraction. Also the trend of the left ventricular elastance was studied for each patient in order to evaluate the benefits produced by the CRT.

RESULTS

The results obtained by means the numerical simulator were in good agreement with clinical data measured on the patients. For each patient also the evolution of the left ventricular elastance was in accordance with the literature data.

CONCLUSION

The cardiovascular numerical model seems to be a useful tool to study the synchronization of the BPM in order to reduce the inter-ventricular and/or intra-ventricular conduction delay and to reproduce the condition of a patient.

Myocardial ischemia in cocaine-user with anomalous origin of the left circumflex coronary artery

The prevalence of anomalous coronary artery is approximately 0.6-1.7% in patients who undergo coronary angiography. These anomalies may cause angina, acute myocardial infarction, syncope and sudden death. Cocaine abuse is now a major health hazard: more than 5 million of Americans are current users. Cocaine abuse can result in coronary artery vasocostriction and the association between cocaine abuse, myocardial ischemia and infarction in the absence of coronary artery disease has been reported. We report the case of a patient with a story of nasally inhaled cocaine abuse presented with exertional chest pain and a perfusion defect of the anterior and inferior-lateral walls of the left ventricle during myocardial perfusion SPECT. The anomalous origin of the left circumflex coronary artery from the righ sinus of Valsalva was detected during coronary angiography and confirmed by the multislice computed tomography (MSCT). Although the coronary angiography is the gold standard of cardiac imaging technique for the diagnosis of coronary artery disease the identification of anomalous coronary arteries is frequently difficult with conventional coronary angiography because of the lack of 3-dimensional (3D) information related to the course of the coronary arteries to the great vessels. The MSCT provides a high spatial resolution, which allows a successful identification of the congenital coronary artery anomalies. This case report provides further a supportive evidence for the role of MSCT in the detection of the coronary artery anomalies.

Elasticity/distensibility of the ascending aorta: basal conditions and simulated conditions from space flights

INTRODUCTION

The hysto-morfological composition of the ascending aorta wall gives to the vessel its characteristic elasticity/distensibility, which is deteriorated due to both physiological (age) and pathological events (hypertension, diabetes, dyslipidemia). This contributes to reduce the wall elasticity and to occurrence of cardiovascular events.

MATERIALS AND METHODS

Thirty young healthy subjects (20 males, 10 females, age <30 yr), were subjected to different postural conditions with and without Lower Body Negative Pressure (LBNP) with conventional procedures, to simulate the microgravity conditions in space flight. During this procedure the cardiovascular parameters and the aorta elasticity were assessed with ecocardiography.

RESULTS

The observation of results and statistical comparison showed that despite different hemodynamic conditions and with significant variation of blood pressure related to posture, elasticity/distensibility did not change significantly.

DISCUSSION

The elasticity/distensibility of arterial vessels is the result of two interdependent variables such as blood pressure and systolic and diastolic diameters. While blood pressure and heart rate vary physiologically in relation to posture, the compensation of the vessel diameters modifications maintains the aortic compliance invariate. Therefore, in young healthy people, despite the significant postural and the sudden pressure changes (equivalent to parietal stress) aortic compliance does not alter. This behavior might be related to the low rate of cardiovascular events that are present in healthy people aged under 30 yrs.

Atrial fibrillation in pure rheumatic mitral valvular disease is expression of an atrial histological change

BACKGROUND

Some of theories try to explain the insurgence of atrial fibrillation (AF) in patients with acute articular rheumatism (AAR). These theories remind the close relation between AF and left atrium, or with valvular vitium degree, or monophasic action potential and histological cardiac structure. In 15 years of work in the academic Department of Heart and Big Vessels in Rome, the Authors studied 243 patients with mitral valvular disease post AAR before and after surgical manoeuvres.

MATERIALS AND METHODS

Patients were divided in order to monitor atrium and ventricle morphological and functional modifications of the valve according to cardiac rhythm. Patients classification was based on surgical therapy adopted, kind of mitral disease and cardiac rhythm. An histological examination was performed, only in patients treated with valvular replacement. During the operation an histological examination in an atrial tissue fragment was performed. 243 patients with mitral valvular disease post AAR with indication in valvular adjustment were studied. The whole population was treated with mitral transcutaneous valvuloplasty (Group B--130 patients) or with mitral valve replacement surgery (Group A--113 patients). These two groups were divided: in Gr.A in Gr.A1 and Gr.A2, and Gr.B in Gr.B1 and Gr.B2, according to cardiac rhythm (sinus rhythm iSR, AF). These subgroups were also divided in Gr.A1SR, Gr.A1AF; Gr.A2SR, Gr.A2AF; Gr.A3SR, Gr.A3AF, according to mitralic disease's kind (stenosis, stenosis/regurgitation, regurgitation). A complex screening were exerted to all patients using echocardio-doppler technology. Morphological parameters of atrium and ventricle, and functional parameters of mitral valve, aorta and tricuspid were evaluated. In Gr.A group patients during the operation were execute a bioptic sampling from left atrium and a consecutive histological valuation.

RESULTS

In Gr.A1 mitral valve area (MtVA) arises smaller (p<0.01) in the group with AF, than those in SR. On the contrary, in subgroups of population of Gr.B there isn't statistic disagreement (p>0.05). Left atrium volume arises elder in patients in AF than in patients in SR (p<0.01), either in patients of subgroups Gr.A1, Gr.A2 or in patients of the whole Gr.B before and after valvuloplasty. In the whole population Gr.B, either Gr.BRS or Gr.BFA, left and right atrial volumes decrease eloquently (p<0.01) after valvoplasty. There's no linear relationship (Pearson r<0.5) between the different subgroups of Gr.A (Gr.A1, Gr.A2, Gr.A3) and those of Gr.B according to mitral valve area (MtVA), volume and left atrial area. Left atrial biopsy shows in patients of SR a normal atrial tissue in the 48% of cases and lightly altered in remaining 52%. On the contrary in patients of AF there are strong anomalies in the 100% of cases.

CONCLUSIONS

According to histological view, atrial volumes variations and valvular area variations before and after surgical treatment, and according also to their comparisons in different groups, authors could assume that insurgence of AF and its chronicization could be an expression of a strong atrial myocardial histological alteration. Furthermore while starting moment of AF genesis is characterized by histological alterations of atrial myocardium (expression of rheumatic chronic disease), its chronicization hands to anatomic-volumetric progressive deterioration of the atrial dysfunction.

The endovascular treatment of traumatic isthmic aortic rupture: three years follow-up

The isthmic aortic rupture represents the main cause of death in car crash accidents, because of closed chest trauma. Early medical and surgical care and endovascular prosthesis treatment with semi-invasive method can improve short and mid term survival. Nine patients with traumatic isthmic aortic rupture underwent endoprosthesis aortic implantation. All the patients were male, mean age 42.48 +/- 17.66 years. Operations included 5 acute cases and 4 chronic cases (chance diagnosis). In all cases the diagnosis was performed by tomodensitometric exam. Cloth prostheses were used (self-expansible Goretex- or Dacron-stent). Three years after the endoprosthesis implantation, we obtained the complete thrombosis of the false aortic lumen in all patients, both acute and chronic, as well as the levelling of the false aneurysms without complications of any kind.