Implantable cardioverter-defibrillator in pregnant women with hypertrophic cardiomyopathy

1. Médico Cardiologista, Médico Assistente da Unidade de Emergência do Instituto do Coração (InCor HCFMUSP). 2. Médico Cardiologista, Médico Assistente da Unidade Coronária do Instituto do Coração (InCor HCFMUSP). 3. Médico Cardiologista, Especialista em Estimulação Cardíaca Artificial, Pós-graduando (Doutorado) do Programa de Pósgraduação em Cirurgia Torácica e Cardiovascular da Faculdade de Medicina da Universidade de São Paulo (FMUSP). 4. Doutora em Ciências Programa de Pós-graduação em Cirurgia Torácica e Cardiovascular da Faculdade de Medicina da Universidade de São Paulo (FMUSP); Enfermeira de Pesquisa da Unidade Cirúrgica de Estimulação Elétrica e Marcapasso do Instituto do Coração (InCor HCFMUSP). Leonardo Jorge Cordeiro de PAULA1, Henrique Barbosa RIBEIRO2, Roberto Márcio de OLIVEIRA JÚNIOR3, Kátia Regina da SILVA4 Rev Bras Cir Cardiovasc 2010; 25(3): 406-409 RELATO DE CASO


INTRODUCTION
Hypertrophic cardiomyopathy (HCM) is an autosomal dominant genetic trait and is characterized by left ventricular hypertrophy, especially of the interventricular septum in the absence of other conditions that justify this anatomic change [1,2].
The sudden cardiac death (SCD), with an annual incidence of 1%, is the most serious complication of this disease [2,3].The risk of fatal arrhythmias increases, however, when: the thickness of the ventricular septum is greater than 30 mm; ventricular tachycardia is detected, the patient reports syncope or when there are sudden deaths in young relatives.The prevention of SCD with the use of automatic cardioverter defibrillator (ICD) has been recommended in high risk patients [1][2][3].
There are few reports of ICD implantation in pregnant women and there is no standard procedure for this condition PAULA, LJC ET AL -Implantable cardioverter-defibrillator in pregnant women with hypertrophic cardiomyopathy Rev Bras Cir Cardiovasc 2010; 25(3): 406-409 [4].The application of shock therapy in pregnant women with IDC, reported in two studies, had no effect on fetal development [4,5].
The aim of this report is to describe the case of two patients with HCM who underwent ICD implantation for prevention of SCD in pregnancy intercourse.

ICD implantation technique
The implant procedure was performed in both cases, under intravenous sedation and local anesthesia.The abdomen of the patients was protected by blanket of lead.The transvenous lead was implanted with the aid of fluoroscopy, in the apical septum of the right ventricle and the pulse generator, housed in the left infraclavicular subcutaneous position (Figure 1).Defibrillation test was not performed.

Special care during pregnancy and childbirth
Both pregnancies were no abnormalities.During delivery, the heart rate was monitored and shock therapies were turned off, turning the previous program of ICD after the procedure.
At the end of puerperium, patients were tested with defibrillation.Under intravenous sedation, ventricular fibrillation was induced, and in both cases, the 20J automatic shock was effective to defibrillate the heart.
During follow-up of 2.7 ± 0.2 years, there were no reports of suggestive episodes of low cerebral blood flow or heart failure.The counters of diagnoses of the ICD did not record appropriate therapy for tachycardia or ventricular fibrillation.One patient presented, however, inappropriate shock therapies for murmur detection and required replacement of the lead, which showed increased pacing impedance.There were no deficiencies or growth disorders in children of these pregnancies.

Fig. 1 -A: Chest radiograph in the anteroposterior position (A) and lateral (B), showing the position of the electrode leads of the ICD implanted through the left cephalic vein. B: Chest radiograph in the anteroposterior position (A) and lateral (B), showing the position of the electrode leads of the ICD implanted through left cephalic vein
A B DISCUSSION Despite its low prevalence, HCM is an important cause of SCD in young individuals [1][2][3][4][5][6].The main risk factors for fatal arrhythmias in these patients are a history of sudden death in young relatives, the presence of syncope of unknown origin, hypotension during exercise, ventricular septal thickness of e" 30 mm and episodes of NSVT on Holter of 24 hours [1][2][3]6].
In this report, the diagnosis of HCM was performed during pregnancy.The identification of multiple risk factors for MSC justified the indication of using ICD during pregnancy.
In addition to the usual anesthetic care for pregnant women, two points deserve special attention: the risk of malformations by use of fluoroscopy used to guide the placement of electrode leads and the lack of knowledge of the consequences of induction of ventricular fibrillation and shock application, that are necessary to test the integrity and efficiency of the system deployed.
Among the alternatives described to prevent fetal exposure to radiation, it has been proposed the implant guided by echocardiography [7] or by electroanatomic mapping [8].In this report, given the low risk of fetal damage from radiation in the third trimester of pregnancy, we chose to fluoroscopy, associated with the use of lead blanket on the abdomen of the pregnant women, as additional protection.
There is no evidence in the literature that the induction of ventricular fibrillation and the shocks applied to the defibrillator test during implantation cause fetal abnormalities.The automatic application of shock in pregnant women already bearer of ICD did not cause maternal or fetal effects [4,5].Moreover, the real need for intraoperative defibrillation test is object of controversy.Clinical studies show that in only 4% of patients shocks are ineffective in reversing ventricular fibrillation induced during ICD implantation [9,10].These studies also showed that ineffective shocks are infrequent in patients with preserved ventricular contractility [9,10].In the cases reported herein, we opted for no defibrillation testing.
The low risk of malformations by radiation after the first trimester of pregnancy, which allowed the use of fluoroscopy, and good ventricular function of patients which avoided the test of defibrillation, became the ICD implantation in these patients a routine procedure, despite the current pregnancy.
years old, at 29 weeks' gestation, presented syncope since nine months without prodrome or associated factors.A transthoracic echocardiogram reveale HCM with ventricular septum of 29 mm and 24-hour ECG detected non-sustained ventricular tachycardia (NSVT).The patient reported she had a brother with ICD due to recovered cardiorespiratory arrest and HCM.Case 2 TIGC, 17 years old, at 26 weeks' gestation, she had repeated episodes of syncope without prodrome or triggering factors, associated with progressive dyspnea.Transthoracic echocardiography diagnosed HCM with interventricular septum with 30 mm thick.She complained of sudden death without etiologic diagnosis in young brother and mother recently diagnosed with HCM.

Table 1 .
Surgical Procedure and ICD Programming