DDD and single-lead VDD pacing: evaluation of atrial signal dynamic changes.

BACKGROUND: Single-lead VDD pacing systems are an alternative to conventional DDD pacemakers in patients with atrioventricular (AV) block and normal sinus function. HYPOTHESIS: The aim of this study was to assess changes of P-wave amplitude occurring in dynamic conditions in two groups of patients with a single-lead VDD and with a DDD pacing system, respectively. METHODS: Twenty-eight patients with second- or third-degree AV block and normal sinus function were enrolled prospectively into the study. Seventeen patients were implanted with a single-lead VDD pacing system and 11 with a DDD pacemaker. Patients were evaluated at 3 months (all patients) and at 6 months (26 patients) at supine and in dynamic conditions (postural changes, hyperventilation, and during exercise). RESULTS: Mean P-wave values at supine were 1.92 +/- 1.10 mV at 3 months and 1.76 +/- 1.01 mV at 6 months for VDD systems, and 4.63 +/- 2.18 mV at 3 months and 4.58 +/- 2.80 mV at 6 months for DDD pacemakers. In dynamic conditions, P-wave amplitude changes compared with supine condition ranged between -74 and +226% in VDD, and between -53 and +138% in DDD; however P-wave amplitudes showed no significant changes compared with baseline. Moreover, changes in atrial signal amplitudes did not occur randomly, and in both systems P-wave amplitudes remained significantly correlated with supine values. CONCLUSIONS: A wide range of P-wave amplitude variations occurs in different postural conditions or during exercise, both with single-lead VDD and DDD pacing systems. However, with appropriate programming of atrial sensitivity based on supine values, constant atrial tracking can be maintained.

High impedance low energy pacing leads: long-term results with a very small surface area steroid-eluting lead compared to three conventional electrodes.

We evaluated the handling performance at implant, and the long-term atrial and ventricular electrical performance of a new generation using a very small surface area (1.2 mm2) steroid-eluting electrode (Medtronic CapSure Z). We compared the performance of CapSure Z to that of traditional passive fixation leads, with and without steroid elution. The study was conducted during 2 years of follow-up. We studied 188 patients (105 males and 83 females; mean age 71 +/- 7 years). All of the patients were implanted with a dual chamber pacemaker and the same type of lead in both chambers. Forty-one patients received CapSure Z leads, 25 patients received Target Tip leads (8-mm2 surface area; no steroid elution), 63 patients received CapSure leads (8-mm2 surface area; steroid elution), and 59 patients received CapSure SP leads (5.8-mm2 surface area; steroid elution). The four groups were homogeneous in regards to sex, age, cardiac disease, and reason for implant. At follow-up, the CapSure Z lead showed sensing values comparable to the other leads, with lower pacing thresholds and higher pacing impedance in both chambers. We evaluated the mean current drained from the pacemaker by the different types of leads when using safe, low energy output settings. We found that by using CapSure Z leads, the mean current was significantly lower than that of the other types of leads (0.42 microA for CapSure Z ventricular lead vs 0.85 for CapSure SP, 1.42 for CapSure, and 1.54 for Target Tip). Thus, the use of the CapSure Z lead, combined with low energy output programming, will increase pacemaker longevity compared to the use of traditional leads and standard output programming.

Antiarrhythmic benefits of dual chamber stimulation with rate-response in patients with paroxysmal atrial fibrillation and chronotropic incompetence: a prospective, multicentre study.

BACKGROUND: While the haemodynamic benefits of DDDR pacing compared with DDD pacing in patients with brady-tachy syndrome and chronotropic incompetence (CI) are well demonstrated, the antiarrhythmic advantage is controversial and so far not clearly demonstrated. AIM: We have performed a prospective, randomized, multicentre study to evaluate the efficacy of DDDR and DDD pacing modes in preventing paroxysmal atrial fibrillation (PAF) episodes in patients with brady-tachy syndrome and CI. METHODS AND RESULTS: Seventy-eight patients were included in the study. All patients had a dual chamber pacemaker implanted and were randomly programmed to DDD or DDDR with a cross over (DDD --> DDDR or vice versa) at 3 months. The final evaluation was performed at 6 months by means of two self-administered symptom questionnaires to evaluate activity. Symptoms of palpitations were analysed and scored. The patients were less symptomatic with the DDDR mode. The number of mode-switch activations compared with symptomatic episodes of PAF confirmed the high rate of asymptomatic PAF episodes in patients with brady-tachy syndrome. We conclude that in a small but well defined population of patients affected by sick sinus syndrome with CI and severely symptomatic PAF, DDDR pacing compared with DDD pacing may offer an additional antiarrhythmic benefit and should be considered the primary mode of pacing.

Dual chamber pacing with optimal AV delay in congestive heart failure: a randomized study.

AIM: A prospective randomized trial was set up to evaluate contractile parameters and quality of life in patients with congestive heart failure. METHODS AND RESULTS: We describe the results from 38 patients in sinus rhythm and with chronic heart failure due to congestive cardiomyopathy, prospectively randomized to optimal medical therapy (Group 1, 19 patients) or optimal medical therapy plus dual chamber pacemaker programmed to optimal AV delay (Group 2, 19 patients). At a 6 month follow-up, 7/19 patients in Group 1 had died compared with 5/19 patients in Group 2. During follow-up, there were few significant changes in evaluated parameters except for mitral regurgitation time, which was prolonged in Group 1 and shortened in Group 2. The systolic left ventricular diameter shortened significantly only in Group 2. An energy and activity questionnaire showed that the effect of DDD pacing in the latter patient population was beneficial. CONCLUSIONS: From these results we may conclude that at the 6 month follow-up DDD pacing with echo-optimized AV interval programming can improve quality of life without affecting survival.

Radiographic assessment of atrial dipole position in single pass lead VDD and DDD pacing. The Multicenter Study Group.

Atrial electrode position was determined by radiographic analysis in 160 patients paced in single-lead VDD for second- or third-degree A-V block, implanted > 1 year with Phymos single pass leads and Phymos 3D pacemakers. The packing lead features an atrial dipole with a 30-mm electrode interspace. In 44% of patients, the upper atrial electrode was positioned within a band of 20 mm centered at the level of the superior vena caval insertion (junctional area) and was in the inferior vena cava or in the atrium in 35% and 21% of cases, respectively. In spite of these different dipole locations, all patients had stable atrium-driven pacing at routine follow-up visits. With the electrode in the junctional area, unipolar stimulation of up to 5 V for 1 ms resulted in stable atrial capture in 63% and 59% of the patients in supine and upright positions, respectively. With the electrode in the atrium, corresponding success rates were 45% and 54%. In the atrium, however, the prevalence of diaphragmatic stimulation was significantly lower than at the junction (10% vs 42% in supine position; 21% vs 47% upright). Though atrial sensing function proved adequate in a wide range of positions, these results suggest that the Phymos lead atrial dipole should be positioned within the atrium, as close as possible to the atrial wall, to maximize the number of VDD patients who might benefit from single-lead DDD pacing.

Clinical reliability of single-lead VDD pacing from evaluation of P-wave sensing under dynamic conditions.

In a group of 20 patients implanted with a single-lead VDD pacing system, a wide interindividual variability was found in P-wave amplitude changes occurring under dynamic conditions, even though they were of minor clinical relevance because constant atrial tracking was maintained.

Italian experience with AutoCapture in conjunction with a membrane lead. Pacesetter Automatic Control of Energy and Membrane Automatic Threshold Evaluation (Pacemate) Study Group.

AutoCapture is a programmable feature of the Pacesetter Microny SR + 2425T VVIR pacemaker, which provides for the automatic capture verification, increase in output in the presence of noncapture and threshold searching, with adjustment of output settings. The effectiveness of this unit in conjunction with the Membrane models 1400T and 1401T bipolar endocardial leads was studied in 54 patients followed at 19 Italian Centers. The patients were randomized at the time of implantation to receive either the model 1400T or the 1401T lead. The electrodes in these leads are covered by a Nafion membrane, which was either impregnated (model 1400T) or not-impregnated (model 1401T) with steroid. This paper reports the data collected over the first six weeks postimplantation. The results of the automatic capture function was compared to the capture threshold measured using the Vario technique at the time of predischarge evaluations, and weeks 1,2, and 6 of postimplant follow-up. The reliability and effectiveness of the pulse generator-lead system allowed for consistent pacing at very low outputs and safety preserved at a programmed output only 0.3 V above the capture threshold.

Intrapatient comparison of atrial and ventricular sensing, pacing threshold, and impedance: benefits with steroid-eluting leads.

We compared the atrial and ventricular bio-electrical effects relating to pacing threshold, pacing impedance, and pacing energy in each of 58 patients to determine the importance of pacing impedance in safe low energy stimulations. The study was conducted during 4 years of follow-up. Of the 58 patients in our study, 31 were stimulated in both chambers with steroid-eluting leads (Capsure 4503 and 4003) and 27 with platinum electrode catheters (Target Tip 4511 and 4011). The two groups were homogeneous in sex, age, cardiopathy, and reason for implant. At 6 months, the mean impedance values for the Target Tip were: 358 +/- 72 omega for the atrium and 443 +/- 72 omega for the ventricle (P < 0.00002); after 1 year, atrium = 386 +/- 77 omega, ventricle = 439 +/- 42 omega (P < 0.04); at 2 years, atrium = 409 +/- 86 omega, ventricle = 510 +/- 94 omega (P < 0.0001); at 3 years, atrium = 428 +/- 81 omega, ventricle = 494 +/- 67 omega (P < 0.02); and at 4 years, atrium = 424 +/- 71 omega and ventricle = 501 +/- 69 omega (P < 0.003). The mean impedance value (for the Capsure) was: atrium = 351 +/- 43 omega, ventricle = 431 +/- 81 omega at 6 months (P < 0.03); at 1 year, atrium = 359 +/- 38 omega, ventricle = 446 +/- 83 omega (P < 0.01); at 2 years, atrium = 304 +/- 124 omega, ventricle = 459 +/- 108 omega (P < 0.0003); at 3 years, atrium = 359 +/- 108 omega, ventricle = 461 +/- 89 omega (P < 0.02); and at 4 years, atrium = 419 +/- 133 omega and ventricle = 515 +/- 75 omega (P < 0.01). In view of the chronic threshold, low energy stimulation was used at follow-up. The mean low energy stimulation values programmed for Target Tip were: atrium = 2.5 V/0.35 ms, ventricle = 2.5 V/0.30 ms; for Capsure, atrium = 2.5 V/0.25 ms, ventricle = 2.5 V/0.25 ms. The mean stimulation energy value was 31% higher in the atrium than in the ventricle with Capsure leads, and 39% higher with Target Tip. Pacing impedance was lower in the atrium than in the ventricle with both leads. Energy consumption in the atrium is significantly greater than in the ventricle with both leads, particularly with Target Tip.

Intrapatient comparison between chronic VVIR and DDD pacing in patients affected by high degree AV block without heart failure.

In patients affected by high degree AV block without preexisting congestive heart failure there is no definite demonstration that DDD pacing gives real clinical advantages in respect to VVIR pacing. We performed an intrapatient, long-term study between the two pacing modes in 14 high degree AV block patients, using the Medtronic Synergyst 7027 dual chamber pacemaker, who could be programmed alternatively in DDD or VVIR mode. After a 4-week run-in period following the pacemaker implant, patients completed a randomized, double-blind, cross-over study to compare the effect of 6-week period VVIR and DDD pacing on symptoms and cardiovascular parameters. A semiquantitative score scale was used to quantify the symptoms of general well-being, palpitations, dizziness, pulsating sensation in the neck or abdomen, shortness of breath at rest and during effort, chest pain, and NYHA classification. The sum of symptom scores was 10.4 +/- 6.7 in VVIR period and 4.6 +/- 2.7 in DDD period (P less than 0.001); five patients (36%) crossed over early from VVIR to DDD because of intolerable symptoms; overall, eight patients preferred the DDD mode and no one preferred the VVIR. Cardiac output at rest (echo-Doppler method) was 4.7 +/- 1.4 versus 5.7 +/- 1.6 liter/min (P less than 0.01), body weight was 65.9 +/- 6.6 versus 64.9 +/- 6.1 kg (P less than 0.02), atrial natriuretic peptide was 236 +/- 112 versus 198 +/- 110 pg/mL (P less than 0.01), respectively, during VVIR and DDD modes. Effort tolerance was similar with the two modes of pacing (68 +/- 15 vs 70 +/- 18 watts/min).(ABSTRACT TRUNCATED AT 250 WORDS)

[Primary angiosarcoma of the right atrium invading the pericardial cavity. Description of a case diagnosed by exploratory thoracotomy and surgically treated with success]. / Angiosarcoma primitivo dell'atrio destro ad espansione in cavità pericardica. Descrizione di un caso diagnosticato con toracotomia esplorativa e trattato chirurgicamente con successo.

The AA. report the case of a 43-year-old woman with an angiosarcoma arising from the right atrial wall and growing into the pericardial cavity. The patient presented with recurrent pericardial effusion initially responsive to medical therapy. The diagnosis was made at the exploratory thoracotomy. Repeated 2D-Echocardiograms did not help for the diagnosis in this particular case. The patient underwent surgical resection of the tumor, chemo- and radiotherapy. After 30 months there are no signs of recurrence or metastasis. In our opinion the frequent recurrence of pericardial effusion in the same patient should be regarded with special suspicion.

[Conservative surgery of the mitral valve. Pre- and post-operative hemodynamic and angiographic study of 20 cases]. / Chirurgie conservatrice de la valve mitrale. Etude hemodynamique et angiographique pre et post-operatoire de 20 cas.

Twenty patients with pure or prevalent mitral regurgitation, undergone mitral valve conservative surgery according to the Carpenter-technique from 1975 to 1979, have been studied. There are 19 women and 1 man, mean age of 25 years (range 11 to 65); 18 had a rheumatic fever; 2 had a mitral valve prolapse due to a degeneration of collagen within the central core of the cordae tendineae, which was the primarily responsible for cordae rupture in 1 case. The clinical and hemodynamic features were severe in a 50 per cent of cases (8 patients in N.Y.H.A. functional class III; 3 in class IV); there was pure mitral regurgitation in 12, combined mitral stenosis and regurgitation in 8; tricuspidalic regurgitation which needed annuloplasty in 5 patients. All the patients have been studied by hemodynamic and angiocardiographic study before and an average of 14 months after surgical treatment. Surgical conservative technique of mitral valve is described; the results are analyzed. All the patients are in N.Y.H.A. functional class I, 14 months after surgical valve therapy. In three cases, a systolic 3/6 murmur which was present immediately after surgical treatment and that not increased in time, remains. EKG left overload is still present in 2 cases; Heart-Chest ratio decreases in all the patients (range 0,61 to 0,51). Atrial fibrillation is present in 6 patients. Hemodynamic findings show: Pulmonary Systolic Pressure (PSP) decreases (45 +/- 4 to 27 +/- 1); Mean Pulmonary Capillary Wedge (PCW) pressure decreases (19 +/- 1 to 11 +/- 1); Total Peripheral Resistance (TRP) (2023 +/- 112 to 1595 +/- 70 dynes sec cm--5), Total Pulmonary Resistances (TPR) (742 +/- 89 to 351 +/- 36), Pulmonary Arterial Resistances (PArtR) (344 +/- 51 to 133 +/- 18 dynes sec cm--5), and Left Ventricle Diastolic Pressure (LVEDP) (12 +/- 1 to 8 +/- 1 mmHg) normalize. The Ejection Fraction (EF) decreases at the most operative control after surgery in 11 patients (56 +/- 3 to 50 +/- 1). Angiographic study shows no regurgitation in 4 patients, a least regurgitation in 13 cases and there is a 2/4 regurgitation in 3 cases only. The AA. have got to an excellent result in 17 patients; a 2/4 degree angiographic regurgitation persist in 3 cases, although a clear clinical improvement. The AA. consider of great utility this surgical valvular management according to a critical review of the efficacy and stability of the results.

[Myocardial infarction and diabetes (author's transl)]. / L'infarto miocardico nel diabete

30 diabetic patients with myocardial infarction were compared with 30 non-diabetic myocardial infarction patients during their hospitalization in an Intensive Care Unit, to observe possible differences at the onset and throughout the course of the infarction syndrome. Myocardial infarction in diabetic cases has an oligosymptomatic onset, often painless, which evolves towards cardiocirculatory decompensation. The frequence of arrhythmias is higher, especially in serious or mortal arrhythmias. Possible pathogenetic reasons for this are briefly discussed.