Surgical ablation of atrial fibrillation with a novel bipolar radiofrequency device

OBJECTIVE

When used for epicardial ablation, unipolar devices do not predictably yield transmural scars. Bipolar radiofrequency proved highly effective on the animal model, but clinical experience is still initial. We describe acute electrophysiologic findings and follow-up results of epicardial ablation with a novel bipolar radiofrequency device.

METHODS

A bipolar ablator was used to perform a simplified left atrial lesion set in 90 consecutive patients with atrial fibrillation undergoing open heart surgery. Pacing thresholds were assessed during surgery to validate 24 pulmonary vein encircling lines (12 patients). Follow-up was 100% complete.

RESULTS

In 67 of 90 patients (84%), mitral valve disease was the main indication to surgery. Atrial fibrillation was continuous in 74 patients (82%) and intermittent in 16 patients (18%). Pacing threshold assessment showed a complete conduction block in 22 of 24 pulmonary vein couples (92%) after a single ablation and in all patients after doubling of the encircling lines. No complications related to the ablation procedure were recorded. The sinus rhythm restoration rate was 79% at 3 months, 87% at 6 months, and 89% (17/18 patients) at 1 year. Postablation organized arrhythmias consisted in right atrial flutter in 2 patients (2%) and left atrial flutter in 6 patients (7%).

CONCLUSIONS

Epicardial ablation with bipolar radiofrequency grants acute transmurality. A simplified lesion set proved highly effective in eliminating atrial fibrillation at 1-year follow-up. Our data suggest that addition of a lesion to the mitral annulus is advisable to prevent left atrial flutter.

A giant left ventricular pseudoaneurysm as a late sequela of aortic valve endocarditis

Left ventricular pseudoaneurysm is an uncommon complication of infective endocarditis, usually presenting within several weeks of the infective episode. We describe a 37-year-old man who presented with exertional dyspnea nearly a year after a prolonged hospitalization for lung abscess. Imaging studies showed new aortic valve regurgitation and a giant pseudoaneurysm extending inferoposteriorly from the left ventricle. At thoracotomy, a perforated aortic valve was found, suggesting a healed endocarditis. The patient underwent successful aneurysmectomy and patch closure with aortic valve repair. This case underscores the potential for very late nonvalvular cardiac complications of infective endocarditis and is also distinctive because of the large size of the pseudoaneurysm.

Dobutamine echocardiography in patients with aortic stenosis and left ventricular dysfunction: predicting outcome as a function of management strategy

STUDY OBJECTIVE

To prospectively address the question whether the assessment of valvular hemodynamics and myocardial function during low-dose dobutamine infusion can guide decision making in patients with aortic stenosis and left ventricular (LV) dysfunction.

PATIENTS AND MEASUREMENTS

Twenty-four patients with aortic stenosis and LV dysfunction (mean ejection fraction, 28%; New York Heart Association class, II to IV) were studied by dobutamine echocardiography assessing mean pressure gradient, aortic valve area, and aortic valve resistance. Patients were prospectively divided into severe and nonsevere aortic stenosis groups according to the response of the valve area to the augmentation of systolic flow. The clinical decision was considered to be concordant with the results of dobutamine echocardiography, when patients with severe aortic stenosis and preserved contractile function were referred by a specialist for aortic valve replacement and when patients with nonsevere aortic stenosis were not. Patients were observed for up to 3 years.

RESULTS

All eight patients with severe aortic stenosis who were referred for surgery survived and had good cardiovascular outcomes, and six of eight patients who were not initially referred for surgery had poor outcomes, including heart failure and sudden cardiac death. The eight patients with nonsevere aortic stenosis did comparatively well without valve replacement. Cardiac death or pulmonary edema occurred in 4 of 16 patients (25%) when the clinical decision was concordant with the results of the dobutamine echocardiogram and occurred in 6 of 8 patients (75%) when the clinical decision was discordant (p = 0.019 [chi(2) test]).

CONCLUSION

Patients with aortic stenosis, LV dysfunction, and relatively low gradients have better outcomes when management decisions are based on the results of dobutamine echocardiograms. Those patients identified as having severe aortic stenosis and preserved contractile reserve by dobutamine echocardiography should undergo surgery, while patients identified as having nonsevere aortic stenosis can be managed conservatively.

[Massive pulmonary embolism--summary of experiences with 13 patients]

Pulmonary embolism is a common event in hospitalized patients. In some cases it presents with hemodynamic collapse, indicating massive obliteration of the pulmonary vasculature and has a very grim prognosis; 2/3 of such patients die within 2 hours of onset of symptoms. We describe our experience in 13 patients with massive pulmonary embolism. An aggressive diagnostic and therapeutic approach, utilizing sophisticated imaging techniques, thrombolytic therapy and surgery, led to the survival of 8 of the patients. Our experience supports an aggressive approach in these seriously ill patients.

Tricuspid valve surgery: recent experience at the Chaim Sheba Medical Center

From 1 January 1989 to 30 June 1992, 35 patients underwent cardiac surgery that included a tricuspid valve (TV) procedure. All had severe TV dysfunction documented by echocardiography, and were in NYHA functional class III-IV. The etiology of TV dysfunction was rheumatic-functional in 19 patients, rheumatic-organic in 13, and infective in 3. Nineteen (54%) had had at least one previous cardiac operation, and in 29 an associated procedure (MVR, AVR, DVR, DVR + CABG) had been performed. The TV was repaired in 27 patients, was replaced by a bioprosthesis in 7, and was excised in 1. There were three (8.6%) operative and two late deaths. Except for two, all surviving patients are in NYHA functional class I-II. In two patients with organic lesions who underwent repair, residual moderate tricuspid regurgitation was observed. We conclude that in these critically ill patients TV surgery can be performed with acceptable results. Long-term fate of a bioprosthesis in the tricuspid position is yet to be determined.

From swirling to a mobile, pedunculated mass--the evolution of left ventricular thrombus despite full anticoagulation. Echocardiographic demonstration

We describe the unusual evolution of a left ventricular thrombus following acute anterior myocardial infarction despite adequate anticoagulation. Serial echocardiographic examinations demonstrated the evolution from swirling in the left ventricle through a solid apical mass gradually dislodging into a mobile, pedunculated mass that was removed surgically to prevent embolization. This report emphasizes the need to follow echocardiographically left ventricular thrombi during treatment with anticoagulants, and to identify morphologic changes that may predict embolization. This case suggests that left ventricular thrombectomy should be considered in selected patients in whom a very high-risk thrombus morphology is detected.

Left ventricular thrombectomy in the early postinfarction period

Emergency left ventricular thrombectomy was performed on four patients soon after infarction. In three patients surgery was carried out after embolisation had occurred and when a large, residual, protruding, mobile thrombus remained in the left ventricle. Surgery was performed in the fourth patient after a high risk thrombus was detected and initial attempts to lyse it had failed. All four patients had an uneventful recovery and were discharged within two weeks of surgery. These cases indicate that the therapeutic option of left ventricular thrombectomy is feasible for patients with acute infarcts and problematic left ventricular thrombi.

Epidural anesthesia with the Trendelenburg position for cesarean section with or without a cardiac surgical procedure in patients with severe mitral stenosis: a hemodynamic study

The hemodynamic effects of epidural anesthesia (EA) with the Trendelenburg position were studied in seven patients with severe mitral stenosis undergoing emergency cesarean section (CS) because of hemodynamic deterioration. In six patients, the CS was immediately followed by an open mitral commissurotomy under general anesthesia, whereas in one patient, the CS was performed alone. A significant reduction in heart rate (120 +/- 5 to 83 +/- 7 beats/min; P less than 0.001) was observed after induction of EA. Mean arterial pressure (MAP) decreased (78 +/- 9 to 55 +/- 5 mm Hg; P less than 0.01) simultaneously with reduction of the pulmonary capillary wedge pressure (PCWP) (37 +/- 4 to 15 +/- 4 mm Hg, P less than 0.001) and cardiac index (CI) (2.4 +/- 0.3 to 1.8 +/- 0.32 L/min/m2; P less than 0.001). However, PCWP could be adjusted by selecting the appropriate angle of the Trendelenburg position. When the PCWP was approximately 25 mm Hg, MAP and Cl increased to 72 +/- 7 mm Hg and 3.1 +/- 0.4 L/min/m2, respectively, and a satisfactory hemodynamic state was achieved. Systemic vascular resistance decreased after induction of EA (2,250 +/- 250 to 1,750 +/- 450 dyne.s.cm-5; P less than 0.001), and remained unchanged during the perioperative period. It is concluded that the combination of epidural anesthesia with tilting of the table is a safe method for urgent CS in pregnant women with critical mitral stenosis in whom termination of pregnancy is indicated because of hemodynamic deterioration.

Continuous rt-PA infusion as a salvage strategy to maintain patency of the infarct artery; safety of high cumulative dose and subsequent emergency coronary artery angioplasty and bypass surgery

Acute re-occlusion of an infarct artery reperfusion attained by thrombolytic therapy may be treated by emergency coronary angioplasty or bypass surgery. Repeated infusion of a thrombolytic agent is an additional treatment strategy. Three patients with reinfarctions that occurred very early after successful reperfusion were treated with continuous infusion of recombinant tissue-type plasminogen activator (rt-PA). These patients received a rt-PA dose of 300-360 mg while they awaited emergency mechanical revascularization procedures. Two patients had coronary angioplasty immediately after receiving repeated infusions of rt-PA and one underwent coronary bypass surgery while receiving a third rt-PA infusion. There were no bleeding complications in the 2 patients who underwent coronary angioplasty, and no excessive bleeding in the patient who received coronary bypass surgery. Thus, repeated continuous rt-PA infusions can be used to maintain the patency of recurrently occluding infarct arteries until definitive mechanical revascularization can be performed.

The perioperative fate of residual gradients after repair of discrete subaortic stenosis and time-related blood levels of catecholamines

The fate of the residual peak systolic left ventricular-aortic gradient was studied perioperatively in 14 patients with membranous discrete subaortic stenosis. In nine (group A) the initial postrepair left ventricular-aortic gradient was greater than 35 mm Hg (mean 56.8 +/- 13.4), and in five (group B) there was no significant postoperative gradient (mean 15.3 +/- 3.2 mm Hg). The operation included membranectomy and myectomy. Peak left ventricular-aortic pressure gradient, endogenous levels of norepinephrine, peak rate of rise of left ventricular pressure, cardiac index, systemic vascular resistance, heart rate, and central venous pressure were recorded at the end of cardiopulmonary bypass and in 3-hour intervals for the next 9 hours. In group A during that period there was a 67% reduction in peak systolic left ventricular-aortic gradient (from 56.8 +/- 13.4 to 18 +/- 14 mm Hg, p less than 0.001). Concomitant reduction in the initial endogenous norepinephrine level was observed (from 982.1 +/- 181 to 422.6 +/- 109 pg/ml, p less than 0.001). A consistent linear relationship between norepinephrine levels and peak systolic left ventricular-aortic gradient was found (r = 0.78). Systolic left ventricular pressure decreased from 174.2 +/- 24.8 to 113.8 +/- 14.7 mm Hg (p less than 0.001). Marked reduction in peak rate of rise of left ventricular pressure (from 3455 +/- 636 to 2161 +/- 680 mm Hg/sec, p less than 0.001) was observed. Cardiac index increased and systemic vascular resistance decreased during the study period (from 2.11 +/- 0.2 to 3.07 +/- 0.26 L/min, p less than 0.001, and from 2172 +/- 331 to 1233 +/- 202 dynes/sec/cm-5, p less than 0.001, respectively). There were no significant changes in heart rate (p = not significant) and central venous pressure p = not significant).

CONCLUSION

Some of the residual perioperative left ventricular-aortic gradients in patients with discrete subaortic stenosis undergoing repairs are dynamic and transient, and are probably related to increased postoperative sympathetic activity.

Relationship of right and left ventricular negative diastolic pressures, hypercontractility, and relief of outflow tract obstructions

Continuous postoperative right and left ventricular diastolic pressures were measured in 12 consecutive patients undergoing pulmonic valvotomy and in 13 consecutive patients undergoing membranectomy and myectomy for discrete subaortic stenosis. All 25 patients had positive preoperative diastolic ventricular pressures. Negative ventricular diastolic pressure was detected immediately postoperatively in all 25. The lowest left ventricular negative diastolic pressure was -38 mm Hg, and the lowest right ventricular negative diastolic pressure was -28 mm Hg. Intravenous administration of volume (blood) reduced the right ventricular negative diastolic pressure significantly (from -14.8 +/- 9.2 to -6.4 +/- 6.8 mm Hg, p less than 0.001) and decreased right ventricular rate of pressure rise from 1100 +/- 320 to 380 +/- 180. Left ventricular negative diastolic pressure was not significantly affected (from -17 +/- 11 to -14.7 +/- 11 mm Hg). Left ventricular negative diastolic pressure disappeared spontaneously 6 to 9 hours postoperatively in association with a spontaneous decrease of left ventricular rate of pressure rise (from 3450 +/- 610 to 2100 +/- 660 mm Hg/sec). We conclude that negative right and left ventricular pressures are common findings immediately after surgical relief of outflow obstructions. Hypercontractility is the main reason for these phenomena. Volume load reduces the right ventricular negative diastolic pressure, but has insignificant effect on left ventricular negative diastolic pressure. The pathogenesis of the hypercontractility is discussed.

Pericardial patch enlargement of Blalock-Hanlon atrial septectomy

A modified Blalock-Hanlon operation is described, in which both the right and left atriotomies were bridged by a generous pericardial patch. This patch significantly enlarged the interatrial communication and markedly increased arterial blood saturation.

Negative right ventricular diastolic pressure after operation for pulmonary valve stenosis: the phenomenon and its relation to volume load and conal contraction

The phenomenon of negative right ventricular diastolic pressure immediately after operation for relief of isolated pulmonary valve stenosis was investigated in 11 patients. Pressures in the right ventricle and pulmonary artery were measured with a catheter tip micromanometer. One patient had a negative right ventricular diastolic pressure before operation. At the end of operation right ventricular diastolic pressure was negative in all 11 patients. The greater the right ventricular hypertrophy, the lower were these diastolic pressures. Negative right ventricular diastolic pressure is thus common in patients after pulmonary valvotomy, but fluid administration may eliminate it. Negative right ventricular diastolic pressure may be the result of hypercontraction and reduced volume of the hypertrophied right ventricle after relief of right ventricular outflow tract obstruction.

Staged surgical treatment of early bacterial endocarditis after surgical repair of tetralogy of Fallot and discrete subaortic stenosis: report of a case

An unconventional method of managing infection of the interventricular Teflon patch in a patient with tetralogy of Fallot is reported. The patch was initially replaced by a new patch. After reinfection, however, removal of the patch and pulmonary banding eradicated the infection, and at a later stage the defect was re-repaired successfully.

The effect of low-dose intravenous nitroglycerin on pulmonary hypertension immediately after replacement of a stenotic mitral valve

The postoperative effect of infusion of nitroglycerin on pulmonary vasomotor dynamics was studied in 28 patients undergoing valve replacement for mitral valve stenosis. A 30% reduction in mean pulmonary arterial pressure (38.74 +/- 8.3 to 26.92 +/- 7.72 mm Hg, p less than .001) and a 48.4% reduction in pulmonary vascular resistance index (12.08 +/- 4.19 to 5.61 +/- 1.61 U/m2, p less than .001) were observed after nitroglycerin. While pulmonary driving pressure (mean pulmonary arterial pressure minus left atrial pressure) dropped by 50.8%, cardiac and stroke volume indexes increased by 25.5% and 24.2%, respectively. The ratio pulmonary/systemic vascular resistance decreased from 34.14% to 20.9% (p less than .001). There were no significant changes in mean systemic arterial pressure (86.89 +/- 13.5 to 83.5 +/- 9.3 mm Hg, p = NS) or heart rate (97.43 +/- 20.45 to 99.36 +/- 20.9 beats/min, p = NS); left and right atrial pressures decreased by 19.5% and 9.5%, respectively. Systemic vascular resistance index decreased by 18.8%. We conclude that low-dose infusion of nitroglycerin reduces the pulmonary vascular resistance in patients with pulmonary hypertension, and consequently results in improvement in immediate postoperative hemodynamics after replacement of a stenotic mitral valve.

Severe pulmonary nocardiosis in a kidney allograft recipient with a low immunological response

A patient with severe pulmonary nocardiosis occurring in the early posttransplant period is presented. Three outstanding features characterized this case: 1) the failure to diagnose this rare opportunitistic pathogen by conventional detection methods necessitated open lung biopsy; 2) the initiation of trimethoprim-sulphamethoxazole therapy resulted in a dramatic clinical response; and 3) an allograft recipient with a low immunological response contracted nocardiosis. His immune status became apparent following pretransplant donor-specific blood transfusion tests, unresponsiveness to third-party transfusion and graft tolerance permitting the permanent withdrawal of azathioprine without graft function impairment.