Oesophageal Vent-Laryngeal Mask to prevent aspiration of gastric contents

The use is described of a prototype device to prevent regurgitationof gastric contents in 16 patients, three of whom appeared tohave been at risk of regurgitation. The "Oesophageal Vent-LaryngealMask" consists of a laryngeal mask attached to an oesophagealtube that has a balloon at the distal end, allowing drainageof any fluid in the oesophagus. (Br. J. Anaesth. 1994; 72: 52–54) Present address: Department of Anaesthesia, King's College Hospital,Denmark Hill, London SE5 9RS.     

ANEURYSM OF SINUS OF VALSALVA DISSECTING INTO THE INTERVENTRICULAR SEPTUM – ECHOCARDIOGRAPHIC DIAGNOSIS (A Case Report)

Aneurysm of sinus of Valsalva dissecting into interventricular septum is a rare entity. We report one such case who was incidentally diagnosed by echocardiography to have this abnormality during evaluation of a clinically suspected isolated aortic regurgitation.KEY WORDS: Aneurysm – dissecting – sinus of Valsalva, Echocardiography     

Electrophysiologic Spectrum of Atrioventricular Nodal Behavior in Patients with Atrioventricular Nodal Reentrant Tachycardia Undergoing Selective Fast or Slow Pathway Ablation

AV Nodal Behavior After Ablation. Introduction; The objective of this report is to delineate the atrioventricular (AV) nodal electrophysiologic behavior in patients undergoing fast or slow pathway ablation for control of their AV nodal reentrant tachycardia (AVNRT).
Methods and Results: One hundred sixteen consecutive patients with symptomatic AVNRT were included. Twenty-two patients underwent fast pathway ablation with complete abolition of AVNRT in all and development of complete AV block in five patients. Of 17 patients with intact AV conduction postablation, 12 had demonstrated antegrade dual pathway physiology during baseline study, which was maintained in three and lost in nine patients postablation. Two patients with successful fast pathway ablation developed uncommon AVNRT necessitating a slow pathway ablation. Twenty-one patients demonstrated both common and uncommon forms of AV nodal reentry during baseline study. The earliest site of atrial activation was close to the His-bundle recording site (anterior interatrial septum) during common variety and the coronary sinus ostium (posterior interatrial septum) during the uncommon AV nodal reentry in all 21 patients. Ninety-six patients underwent successful slow pathway ablation. Among these, the antegrade dual pathway physiology demonstrable during baseline study (60 patients) was maintained in 25 and lost in 35 patients postablation.
Conclusion: These data suggest that: (1) dual pathway physiology may persist after successful ablation, which might be a reflection of multiple reentrant pathways in patients with AVNRT: and (2) the retrograde pathways during common and uncommon AVNRT have anatomically separate atrial breakthroughs. These findings have important electrophysiologic implications regarding the prevailing concept of the AV nodal physiology in patients with AVNRT.     

The Effects of Rate and Rhythm Control on Blood Pressure and Antihypertensive Drug Usage in Patients with Atrial Fibrillation and Hypertension Enrolled in the AFFIRM Trial

AF and HTN in the AFFIRM trial . Introduction: Atrial fibrillation (AF) has been shown to be associated with activation of the renin–angiotensin–aldosterone system, endothelial dysfunction, and increased sympathetic activity, all of which could lead to hypertension (HTN). While the effects of HTN on AF incidence and arrhythmogenesis have been reported, the long‐term effects of AF on blood pressure (BP) remain unknown. We hypothesized that a rate control strategy is associated with an increase in BP and/or antihypertensive drug therapy when compared with a rhythm control strategy in patients with a history of AF and HTN. Methods and Results: Using the intention to treat method, BP readings and the number of antihypertensive medication categories were analyzed over the first year of follow‐up in patients with AF and HTN enrolled in the AFFIRM trial. No clinically significant changes in BP occurred. Medication data were available in 2,876 patients. In the rate control group, 27.8% of patients required a net increase in the number of antihypertensive medications when compared to 18.3% in the rhythm control group (P < 0.001). Furthermore, 27.1% of patients in the rate control group had a net decrease in the number of antihypertensive medications when compared with 41.7% in the rhythm control group (P < 0.001). Conclusions: Our findings suggest that AF could be contributing to BP elevation in patients with a history of HTN and that a rhythm control strategy might result in a decrease in BP in these patients. This hypothesis however, requires future testing. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1094‐1098)     

Correlation of Spontaneous and Induced Premature Atrial Complexes Initiating Atrial Fibrillation in Humans: Electrophysiologic Parameters for Guiding Therapy

INTRODUCTION: The low frequency of spontaneous premature atrial contractions (PACs) may be an impediment to mapping and ablation of atrial fibrillation (AF). It has been shown that PACs following external or internal cardioversion of AF can initiate AF. If this method could reproducibly induce PACs from the same location as spontaneous PACs, it would be clinically significant. High-resolution noncontact mapping can map a single beat, should help identify the sites of spontaneously occurring PACs and PACs induced following cardioversion of spontaneous or induced AF, and could help correlate the trigger sites for AF induction. METHODS AND RESULTS: Twelve patients (8 men and 4 women; mean age 49+/-10 years) with spontaneous PACs were included in the study. In all patients, AF was induced and subsequently cardioverted to assess and map isolated PACs or PACs that induced AF. Using the EnSite 3000 noncontact mapping system, mapping was performed of spontaneously occurring isolated PACs and PACs that induced AF and PACs (both with and without AF) that occurred on at least two different occasions following cardioversion. The locations of the spontaneous and the induced PACs were similar; 97% of induced PACs came from the same locations as those of spontaneous PACs (P = 0.5). Radiofrequency lesions guided by this mapping technique were delivered at 14 pulmonary vein sites. Following a single ablation attempt during a mean follow-up of 19+/-4 weeks, 42% of the patients were in sinus rhythm and drug-free, whereas an additional 24% of patients could be maintained in sinus rhythm on drugs that had failed before. CONCLUSION: There is a high degree of correlation between spontaneous and induced PACs as the trigger sites for AF initiation. Cardioversion of spontaneous or induced AF could be used as an electrophysiologic parameter for guiding therapy.     

Right Side Implant of the Unipolar Single Lead Defihrillation System

The active can defibrillator has been designed for implantation in the left prepectoral region. Whether this system can be successfully implanted on the right side is unknown. We describe six cases in which placement of the unipolar single lead defibrillation system was successfully attempted in the right prepectoral region due to impediments on the left side. The mean age of the patients was 62 ± 12 years. Five patients had is–chemic heart disease and one idiopathic dilated cardiomyopathy. The endocardial defibrillation electrode was placed in the right ventricle through the right subclavian vein and positioned at the apex in two patients and in the septal position in four patients. Defibrillation threshold testing was performed using a step-up/step-down protocol beginning at 12 J with 3-J increments or decrements. Defibrillation threshold was defined as the lowest energy of the first shock able to terminate ventricular fibrillation. The generator models used were the Medtronic 7218C in 1 patient, the Medtronic 7219C in 3 patients, and the Ventritex Cadet 115 AC in 2 patients. The mean defibrillation threshold was 15 ± 3 J. The defibrillation thresholds were retested at 1,3, and 6 months, and showed no significant change in five patients but decreased from 15 J to 12 J in one patient. The presence of impediments on the left side should not preclude attempts to place the unipolar active can system in the right prepectoral region.     

The Effect of Biphasic Waveform Tilt in Transvenous Atrial Defibrillation

Atrial defibrillation can be accomplished using low energy shocks and transvenous catheters. The biphasic waveform tilt required to achieve optimal atrial defibrillation thresholds (ADFTs) is, however, not known. The effect of single capacitor biphasic waveform tilt modification on ADFT was assessed in 20 patients. Following AF induction the defibrillation pulses were delivered between the catheters positioned in the coronary sinus and the right atrium.
The single capacitor biphasic waveform shocks, delivered over the same pathways, consisted of 65% tilt (65/65 biphasic waveform) to produce an overall tilt of 88%, or 50% tilt (50/50 biphasic waveform) to produce an overall tilt of 75%. Although 65/65 biphasic waveform delivers more energy, the shorter duration 50/50 biphasic waveform reduced stored energy ADFT 21%, from 1.34 ± 0.82 J with 65/65 biphasic to 2.06 ± 0.81 J. These differences were not statistically significant. Nine patients had lower ADFT with 50/50 biphasic waveform while five patients had lower ADFT with 65/65 biphasic waveform. Equivalent reduction in ADFT was seen in the remaining six patients. The ADFT was 0.83 ± 0.65 J when both tilts were considered. In conclusion, biphasic waveform tilt modification may affect the ADFT in an individual patient. The optimal biphasic waveform for ADFT is not known.     

Comparison of Biphasic and Monophasic Pulses: Does the Advantage of Biphasic Shocks Depend on the Waveshape?

With present implantable defibrillators, the ability to vary the defibrillation technique has been shown to increase the number of patients suitable for transvenous system. As newer waveforms become available, the need for a flexible device may change. In addition, although it has been shown that the option of biphasic waveform may increase the defibrillation efficacy, this may depend upon the shape of the biphasic waveform used. Thirty patients undergoing transvenous defibrillator implant were included in the study. In 20 patients (group I), defibrillation efficacy of simultaneous monophasic, sequential monophasic, and biphasic waveform with 50% tilt was determined randomly. Similarly, in ten patients (group II) testing of simultaneous monophasic shocks and biphasic waveforms with 65% and 80% tilt was performed in random order. The electrode system used consisted of two transvenous leads and a subcutaneous patch in all 30 patients. In group I, 50% tilt biphasic waveform consistently provided similar or better defibrillation efficacy compared to monophasic waveforms (biphasic 7.5 ±5.1 joules vs simultaneous 17 ± 7.8 joules, P < 0.01; and vs sequential 17 ± 8.4 joules, P <0.01). In group II, 65% tilt biphasic pulse required less energy for defibrillation as compared with simultaneous monophasic shocks (9.6 ± 4.5 joulesvs 15.6 ± 5.1 joules, P = 0.04). No significant difference was observed in terms of defibrillation threshold between 80% tilt biphasic shocks and simultaneous monophasic pulses (11.8 ± 6 joules vs 15.6 ±5.1 joules, P = NS). Biphasic shocks with smaller tilt delivered using a triple lead system more uniformly improved defibrillation threshold over standard monophasic waveforms.     

Applying operations research to health planning: locating health centres in Zambia

Accessibility to health care facilities, particularly in ruralareas with dispersed populations, is a major concern of primaryhealth care policies. The physical accessibility of rural healthcare facilities is often assessed in terms of their locationrelative to those who will use them. However, the final choiceof location for a facility will often depend on a trade-offbetween many criteria including not only its physical accessibilityfor the users, but also its costs to the provider, its politicalvalue to local leaders, etc. In this paper a technique willbe presented which can help health policy-makers and plannersin deciding on the optimum location for rural health facilitiesby taking into account the different criteria of these variousinterest groups. The technique is intended to help in a prospectiveevaluation of alternative feasible locations; it is thereforeappropriate for operations research. Two examples are takenfrom Zambia to illustrate how the approach could be used inchoosing the most suitable location for upgrading a rural healthcentre in a district.